Asthma Disease Essay

Asthma is a lung disease that makes breathing difficult for millions of Americans, both young and old. There is no cure for asthma, but the good news is it can be managed and treated so you can live a normal, healthy life. (http://www.lung.org/lung-disease/asthma/) Asthma is characterized by recurrent episodes of wheezing, shortness of breath, chest tightness, and coughing. Sputum may be produced from the lung by coughing but is often hard to bring up. During recovery from an attack, it may appear pus-like due to high levels of white blood cells called eosinophils. Symptoms are usually worse at night and in the early morning or in response to exercise or cold air. Some people with asthma rarely experience symptoms, usually in response to triggers, whereas others may have marked and persistent symptoms. Asthma is a common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction and bronchospasm. Common symptoms include wheezing, coughing, chest tightness, and shortness of breath. Asthma is thought to be caused by a combination of genetic and environmental factors. Its diagnosis is usually based on the pattern of symptoms, response to therapy over time and spirometry. It is clini cally classified according to the frequency of symptoms, forced expiratory volume in one second, and peak expiratory flow rate. Treatment of acute symptoms is usually with an inhaled short-acting beta-2 agonist and oral corticosteroids. In very severe cases, intravenous corticosteroids, magnesium sulfate, and hospitalization may be required. Symptoms can be prevented by avoiding triggers, such as allergens and irritants, and by the use of inhaled corticosteroids. Long-acting beta agonists or leukotriene antagonists may be used in addition to inhaled corticosteroids if asthma symptoms remain uncontrolled. The occurrence of asthma has increased significantly since the 1970s. In 2011, 235–300 million people globally have been diagnosed with asthma, Signs and symptoms Asthma is characterized by recurrent episodes of wheezing, shortness of breath, chest tightness, and coughing. Sputum may be produced from the lung by coughing but is often hard to bring up. During recovery from an attack,  it may appear pus-like due to high levels of white blood cells called eosinophils. Symptoms are usually worse at night and in the early morning or in response to exercise or cold air. Some people with asthma rarely experience symptoms, usually in response to triggers, whereas others may have marked and persistent symptoms. Associated conditions A number of other health conditions occur more frequently in those with asthma, including gastro-esophageal reflux disease, rhinosinusitis, and obstructive sleep apnea. Psychological disorders are also more common, with anxiety disorders occurring in between 16–52% and mood disorders in 14–41%. However, it is not known if asthma causes psychological problems or if psychological problems lead to asthma.

Forward the Foundation Chapter 11

9 We all have our small illusions and Cleon-Emperor of the Galaxy, King of Trantor, and a wide collection of other titles that on rare occasions could be called out in a long sonorous roll-was convinced that he was a person of democratic spirit. It always angered him when he was warned off a course of action by Demerzel (or, later, by Seldon) on the grounds that such action would be looked on as â€Å"tyrannical† or â€Å"despotic.† Cleon was not a tyrant or despot by disposition, he was certain; he only wanted to take firm and decisive action. He spoke many times with nostalgic approval of the days when Emperors could mingle freely with their subjects, but now, of course, when the history of coups and assassinations-actual or attempted-had become a dreary fact of life, the Emperor had, of necessity, been shut off from the world. It is doubtful that Cleon, who had never in his life met with people except under the most constricted of conditions, would really have felt at home in offhand encounters with strangers, but he always imagined he would enjoy it. He was excited, therefore, for the rare chance of talking to one of the underlings on the grounds, to smile and to doff the trappings of Imperial rule for a few minutes. It made him feet democratic. There was this gardener whom Seldon had spoken of, for instance. It would be fitting, even a pleasure, to reward him belatedly for his loyalty and bravery-and to do so himself, rather than leaving it to some functionary. He therefore arranged to meet the fellow in the spacious rose garden, which was in full bloom. That would be appropriate, Cleon thought, but, of course, they would have to bring the gardener there first. It was unthinkable for the Emperor to be made to wait. It is one thing to be democratic, quite another to be inconvenienced. The gardener was waiting for him among the roses, his eyes wide, his lips trembling. It occurred to Cleon that it was possible that no one had told the man the exact reason for the meeting. Well, he would reassure him in kindly fashion-except that, now he came to think of it, he could not remember the fellow's name. He turned to one of the officials at his side and said, â€Å"What is the gardener's name?† â€Å"Sire, it is Mandell Gruber. He has been a gardener here for thirty years.† The Emperor nodded and said, â€Å"Ah, Gruber. How glad I am to meet a worthy and hardworking gardener.† â€Å"Sire,† mumbled Gruber, his teeth chattering. â€Å"I am not a man of many talents, but it is always my best I try to do on behalf of your gracious self.† â€Å"Of course, of course,† said the Emperor, wondering if the gardener suspected him of sarcasm. These men of the lower class lacked the finer feelings that came with refinement and manners, which always made any attempt at democratic display difficult. Cleon said, â€Å"I have heard from my First Minister of the loyalty with which you once came to his aid and of your skill in taking care of the grounds. The First Minister tells me that he and you are quite friendly.† â€Å"Sire, the First Minister is most gracious to me, but I know my place. I never speak to him unless he speaks first.† â€Å"Quite, Gruber. That shows good manners on your part, but the First Minister, like myself, is a man of democratic impulses and I trust his judgment of people.† Gruber bowed low. The Emperor said, â€Å"As you know, Gruber, Chief Gardener Malcomber is quite old and longs to retire. The responsibilities are becoming greater than even he can bear.† â€Å"Sire, the Chief Gardener is much respected by all the gardeners. May he be spared for many years so that we can all come to him for the benefit of his wisdom and judgment.† â€Å"Well said, Gruber,† said the Emperor carelessly, â€Å"but you very well know that that is just mumbo-jumbo. He is not going to be spared, at least not with the strength and wit necessary for the position. He himself requests retirement within the year and I have granted him that. It remains to find a replacement.† â€Å"Oh, Sire, there are fifty men and women in this grand place who could be Chief Gardener.† â€Å"I dare say,† said the Emperor, â€Å"but my choice has fallen upon you.† The Emperor smiled graciously. This was the moment he had been waiting for. Gruber would now, he expected, fall to his knees in an ecstasy of gratitude. He did not and the Emperor frowned. Gruber said, â€Å"Sire, it is an honor that is too great for me-entirely.† â€Å"Nonsense,† said Cleon, offended that his judgment should be called into question. â€Å"It is about time that your virtues are recognized. You will no longer have to be exposed to weather of all kinds at all times of the year. You will have the Chief Gardener's office, a fine place, which I will have redecorated for you, and where you can bring your family. You do have a family, don't you, Gruber?† â€Å"Yes, Sire. A wife and two daughters. And a son-in-law.† â€Å"Very good. You will be very comfortable and you will enjoy your new life, Gruber. You will be indoors, Gruber, and out of the weather, like a true Trantorian.† â€Å"Sire, consider that I am an Anacreonian by upbringing-â€Å" â€Å"I have considered, Gruber. All worlds are alike to the Emperor. It is done. The new job is what you deserved.† He nodded his head and stalked off. Cleon was satisfied with this latest show of his benevolence. Of course, he could have used a little more gratitude from the fellow, a little more appreciation, but at least the task was done. And it was much easier to have this done than to settle the matter of the failing infrastructure. Cleon had, in a moment of testiness, declared that whenever a breakdown could be attributed to human error, the human being in question should forthwith be executed. â€Å"Just a few executions,† he said, â€Å"and it will be remarkable how careful everyone will become.† â€Å"I'm afraid, Sire,† Seldon had said, â€Å"that this type of despotic behavior would not accomplish what you wish. It would probably force the workers to go on strike-and if you try to force them back to work, there would then be an insurrection-and if you try to replace them with soldiers, you will find they do not know how to control the machinery, so that breakdowns will begin to take place much more frequently.† It was no wonder that Cleon turned to the matter of appointing a Chief Gardener with relief. As for Gruber, he gazed after the departing Emperor with the chill of sheer horror. He was going to be taken from the freedom of the open air and condemned to the constriction of four walls. Yet how could one refuse the Emperor? 10 Raych looked in the mirror of his Wye hotel room somberly (it was a pretty run-down hotel room, but Raych was not supposed to have too many credits). He did not like what he saw. His mustache was gone; his sideburns were shortened; his hair was clipped at the sides and back. He looked-plucked. Worse than that. As a result of the change in his facial contours, he looked baby-faced. It was disgusting. Nor was he making any headway. Seldon had given him the security reports on Kaspal Kaspalov's death, which he had studied. There wasn't much there. Just that Kaspalov had been murdered and that the local security officers had come up with nothing of importance in connection with that murder. It seemed quite clear that the security officers attached little or no importance to it, anyway. That was not surprising. In the last century, the crime rate had risen markedly in most worlds, certainly in the grandly complex world of Trantor, and nowhere were the local security officers up to the job of doing anything useful about it. In fact, the security establishment had declined in numbers and efficiency everywhere and (while this was hard to prove) had become more corrupt. It was inevitable this should be so, with pay refusing to keep pace with the cost of living. One must pay civil officials to keep them honest. Failing that, they would surely make up for their inadequate salaries in other ways. Seldon had been preaching this doctrine for some years now, but it did no good. There was no way to increase wages without increasing taxes and the populace would not sit still for increased taxes. It seemed they would rather lose ten times the credits in graft. It was all part (Seldon had said) of the general deterioration of Imperial society over the previous two centuries. Well, what was Raych to do? He was here at the hotel where Kaspalov had lived during the days immediately before his murder. Somewhere in the hotel there might be someone who had something to do with that-or who knew someone who had. It seemed to Raych that he must make himself conspicuous. He must show an interest in Kaspalov's death and then someone would get interested in him and pick him up. It was dangerous, but if he could make himself sound harmless enough, they might not attack him immediately. Well- Raych looked at his timeband. There would be people enjoying their predinner aperitifs in the bar. He might as well join them and see what would happen-if anything. 11 In some respects, Wye could be quite puritanical. (This was true of all the sectors, though the rigidity of one sector might be completely different from the rigidity of another.) Here, the drinks were not alcoholic but were synthetically designed to stimulate in other ways. Raych did not like the taste, finding himself utterly unused to it, but it meant that he could sip his drink slowly and look around. He caught the eye of a young woman several tables away and had difficulty in looking away. She was attractive and it was clear that Wye's ways were not puritanical in every fashion. After a few moments, the young woman smiled slightly and rose. She drifted toward Raych's table, while Raych watched her speculatively. He could scarcely (he thought with marked regret) afford a side adventure just now. She stopped for a moment when she reached Raych and then let herself slide smoothly into an adjacent chair. â€Å"Hello,† she said. â€Å"You don't look like a regular here.† Raych smiled. â€Å"I'm not. Do you know all the regulars?† â€Å"Just about,† she said, unembarrassed. â€Å"My name is Manella. What's yours?† Raych was more regretful than ever. She was quite tall, taller than he himself was without his heels-something he always found attractive-had a milky complexion, and long, softly wavy hair that had distinct glints of dark red in it. Her clothing was not too garish and she might, if she had tried a little harder, have passed as a respectable woman of the not-too-hardworking class. Raych said, â€Å"My name doesn't matter. I don't have many credits.† â€Å"Oh. Too bad.† Manella made a face. â€Å"Can't you get a few?† â€Å"I'd like to. I need a job. Do you know of any?† â€Å"What kind of job?† Raych shrugged. â€Å"I don't have any experience in anything fancy, but I ain't proud.† Manella looked at him thoughtfully. â€Å"I'll tell you what, Mr. Nameless. Sometimes it doesn't take any credits at all.† Raych froze at once. He had been successful enough with women, but with his mustache-his mustache. What could she see in his baby face? He said, â€Å"Tell you what. I had a friend living here a couple of weeks ago and I can't find him. Since you know all the regulars, maybe you know him. His name is Kaspalov.† He raised his voice slightly. â€Å"Kaspal Kaspalov.† Manella stared at him blankly and shook her head. â€Å"I don't know anybody by that name.† â€Å"Too bad. He was a Joranumite and so am I.† Again, a blank look. â€Å"Do you know what a Joranumite is?† She shook her head. â€Å"N-no. I've heard the word, but I don't know what it means. Is it some kind of job?† Raych felt disappointed. He said, â€Å"It would take too long to explain.† It sounded like a dismissal and, after a moment of uncertainty, Manella rose and drifted away. She did not smile and Raych was a little surprised that she had remained as long as she did. (Well, Seldon had always insisted that Raych had the capacity to inspire affection-but surely not in a businesswoman of this sort. For them, payment was the thing.) His eyes followed Manella automatically as she stopped at another table, where a man was seated by himself. He was of early middle age, with butter-yellow hair, slicked back. He was very smooth-shaven, but it seemed to Raych that he could have used a beard, his chin being too prominent and a bit asymmetric. Apparently Manella had no better luck with this beardless one. A few words were exchanged and she moved on. Too bad, but surely it was impossible for her to fail often. She was unquestionably desirable. Raych found himself thinking, quite involuntarily, of what the upshot would be if he, after all, could-And then Raych realized that he had been joined by someone else. It was a man this time. It was, in fact, the man to whom Manella had just spoken. He was astonished that his own preoccupation had allowed him to be thus approached and, in effect, caught by surprise. He couldn't very well afford this sort of thing. The man looked at him with a glint of curiosity in his eyes. â€Å"You were just talking to a friend of mine.† Raych could not help smiling broadly. â€Å"She's a friendly person.† â€Å"Yes, she is. And a good friend of mine. I couldn't help overhearing what you said to her.† â€Å"Wasn't nothing wrong, I think.† â€Å"Not at all, but you called yourself a Joranumite.† Raych's heart jumped. His remark to Manella had hit dead-center after all. It had meant nothing to her, but it seemed to mean something to her â€Å"friend.† Did that mean he was on the road now? Or merely in trouble? 12 Raych did his best to size up his new companion, without allowing his own face to lose its smooth naivete. The man had sharp greenish eyes and his right hand clenched almost threateningly into a fist as it rested on the table. Raych looked owlishly at the other and waited. Again, the man said, â€Å"I understand you call yourself a Joranumite.† Raych did his best to look uneasy. It was not difficult. He said, â€Å"Why do you ask, mister?† â€Å"Because I don't think you're old enough.† â€Å"I'm old enough. I used to watch Jo-Jo Joranum's speeches on holovision.† â€Å"Can you quote them?† Raych shrugged. â€Å"No, but I got the idea.† â€Å"You're a brave young man to talk openly about being a Joranumite. Some people don't like that.† â€Å"I'm told there are lots of Joranumites in Wye.† â€Å"That may be. Is that why you came here?† â€Å"I'm looking for a job. Maybe another Joranumite would help me.† â€Å"There are Joranumites in Dahl, too. Where are you from?† There was no question that he recognized Raych's accent. That could not be disguised. He said, â€Å"I was born in Millimaru, but I lived mostly in Dahl when I was growing up.† â€Å"Doing what?† â€Å"Nothing much. Going to school some.† â€Å"And why are you a Joranumite?† Raych let himself heat up a bit. He couldn't have lived in downtrodden, discriminated-against Dahl without having obvious reasons for being a Joranumite. He said, â€Å"Because I think there should be more representative government in the Empire, more participation by the people, and more equality among the sectors and the worlds. Doesn't anyone with brains and a heart think that?† â€Å"And you want to see the Emperorship abolished?† Raych paused. One could get away with a great deal in the way of subversive statements, but anything overtly anti-Emperor was stepping outside the bounds. He said, â€Å"I ain't saying that. I believe in the Emperor, but ruling a whole Empire is too much for one man.† â€Å"It isn't one man. There's a whole Imperial bureaucracy. What do you think of Hari Seldon, the First Minister?† â€Å"Don't think nothing about him. Don't know about him.† â€Å"All you know is that people should be more represented in the affairs of government. Is that right?† Raych allowed himself to look confused. â€Å"That's what Jo-Jo Joranum used to say. I don't know what you call it. I heard someone once call it ‘democracy,' but I don't know what that means.† â€Å"Democracy is something that some worlds have tried. Some still do. I don't know that those worlds are run better than other worlds. So you're a democrat?† â€Å"Is that what you call it?† Raych let his head sink, as if in deep thought. â€Å"I feel more at home as a Joranumite.† â€Å"Of course, as a Dahlite-â€Å" â€Å"I just lived there awhile.† â€Å"-you're all for people's equalities and such things. The Dahlites, being an oppressed group, would naturally think in that fashion.† â€Å"I hear that Wye is pretty strong in Joranumite thinking. They're not oppressed.† â€Å"Different reason. The old Wye Mayors always wanted to be Emperors. Did you know that?† Raych shook his head. â€Å"Eighteen years ago,† said the man, â€Å"Mayor Rashelle nearly carried through a coup in that direction. So the Wyans are rebels, not so much Joranumite as anti-Cleon.† Raych said, â€Å"I don't know nothing about that. I ain't against the Emperor.† â€Å"But you are for popular representation, aren't you? Do you think that some sort of elected assembly could run the Galactic Empire without bogging down in politics and partisan bickering? Without paralysis?† Raych said, â€Å"Huh? I don't understand.† â€Å"Do you think a great many people could come to some decision quickly in times of emergency? Or would they just sit around and argue?† â€Å"I don't know, but it doesn't seem right that just a few people should have all the say over all the worlds.† â€Å"Are you willing to fight for your beliefs? Or do you just like to talk about them?† â€Å"No one asked me to do any fighting,† said Raych. â€Å"Suppose someone did. How important do you think your beliefs about democracy-or Joranumite philosophy-are?† â€Å"I'd fight for them-if I thought it would do any good.† â€Å"There's a brave lad. So you came to Wye to fight for your beliefs.† â€Å"No,† said Raych uncomfortably, â€Å"I can't say I did. I came to look for a job, sir. It ain't easy to find no jobs these days-and I ain't got no credits. A guy's gotta live.† â€Å"I agree. What's your name?† The question shot out without warning, but Raych was ready for it. â€Å"Planchet, sir.† â€Å"First or last name?† â€Å"Only name, as far as I know.† â€Å"You have no credits and, I gather, very little education.† â€Å"Afraid so.† â€Å"And no experience at any specialized job?† â€Å"I ain't worked much, but I'm willing.† â€Å"All right. I'll tell you what, Planchet.† He took a small white triangle out of his pocket and pressed it in such a way as to produce a printed message on it. Then he rubbed his thumb across it, freezing it. â€Å"I'll tell you where to go. You take this with you and it may get you a job.† Raych took the card and glanced at it. The signals seemed to fluoresce, but Raych could not read them. He looked at the other man warily. â€Å"What if they think I stole it?† â€Å"It can't be stolen. It has my sign on it and now it has your name.† â€Å"What if they ask me who you are?† â€Å"They won't. You say you want a job. There's your chance. I don't guarantee it, but there's your chance.† He gave him another card. â€Å"This is where to go.† Raych could read this one. â€Å"Thank you,† he mumbled. The man made little dismissing gestures with his hand. Raych rose and left-and wondered what he was getting into.

Ballroom Dancing

20 TYPES OF BALLROOM DANCING Cha Cha The Cha Cha is a lively, flirtatious ballroom dance full of passion and energy. The classic â€Å"Cuban motion† gives the Cha Cha its unique style. Partners work together to synchronize each movement in perfect alignment. Foxtrot The Foxtrot is a ballroom dance that is lots of fun and simple to learn†¦ an excellent dance for beginners. The Foxtrot is a smooth dance in which dancers make long, flowing movements across the floor. Jive Jive is a ballroom dance style that originated in the United States from African-Americans. It is a lively form of Swing dance, and a variation of the Jitterbug. Lindy Hop The Lindy Hop is the ballroom dance considered to be the father of all Swing dances. It is known for its unique, athletic style, and often contains aerial jumps, twists and flips. Mambo The Mambo is one of the most sensual and emotional Latin American ballroom dances. Swaying hip movements, facial expressions, arm movements and holds all add to the sensuality of the dance. Paso Doble The Paso Doble is one of the liveliest ballroom dances, originating in southern France. It is modeled after the sound, drama, and movement of the Spanish bullfight. Quickstep The Quickstep is a quick version of the Foxtrot. It is a ballroom dance comprised of extremely quick stepping, syncopated feet rhythms, and runs of quick steps. The Quickstep is exciting to watch, but among the most difficult of all the ballroom dances. Rumba The Rumba is considered by many to be the most romantic and sensual of all Latin ballroom dances. It is often referred to as the â€Å"Grandfather of the Latin dances. † Samba Possibly the most popular of all Brazilian ballroom dances, the Samba is popular with young people as well as older generations. The Samba can be performed solo or with a partner. Tango The Tango is one of the most fascinating of all ballroom dances. This sensual ballroom dance originated in South America in the early twentieth century. Viennese Waltz The Viennese Waltz is a quick rotating ballroom dance with a subtle rise and fall. It is considered by most to be one of the most difficult dances to learn. The simple and elegant rotational movement characterizes the Viennese Waltz. Waltz The Waltz is one of the smoothest ballroom dances. It is a progressive dance marked by long, flowing movements, continuous turns, and â€Å"rise and fall. The dance is so graceful and elegant, Waltz dancers appear to glide around the floor with almost no effort. East Coast Swing East Coast Swing (ECS) is a form of social partner dance. It belongs to the group of swing dances. It is danced under fast swing music, including rock and roll and boogie-woogie. Orininally known as â€Å"Eastern Swing† by Arthur Murray Studios, the name East Coast Swing became more common betwe en 1975 and 1980. Bolero Bolero is a genre of slow-tempo Latin music and its associated dance and song. There are Spanish and Cuban forms which are both significant and which have separate origins. 1]The term is also used for some art music. In all its forms, the bolero has been popular for over a century. The Day We Fall in Love – Park Shin  Hye Korean Version : Eonjebuteo yeosseulkka nae mame jakku deureowa Dugun dugun tteolryeowa jageun neoui misokkajido Oraen sigan dongan na gidaryeoun unmyeong gateun sarang Geugeon neoyeosseo, nan alsu isseo Oh~ nae sarang geudaeran geol Geudaeneun nae mame on jongil noganaerin somsatang gata Geudaeneun nae mame nunbusige dagaon mujigae gata Naegeman deulrige dalkomhan mogsoriro yaegihaejulhae Cheoeumbuteo geudae maeum do everyday loving me saranghae just be my love Waenji jakku utge dwae jangnanseureon ne moksori Jageun du nune bichin nae moseub majeodo tteolryeowa Oraen sigan dongan na gidaryeoun unmyeong gateun sarang Geugeon neoyeosseo nan alsuisseo Oh~ nae sarang geudaeran geol Geudaeneun nae mame on jongil noganaerin somsatang gata Geudaeneun nae mame nunbusige dagaon mujigae gata Naegeman deulrige dalkomhan mogsoriro yaegihaejulhae Cheoeumbuteo geudae maeum do everyday loving me saranghae just be my love Geudaen aranayo Uri ireohge saranghage doeneun nal Geudaen mideonnayo Haneureseo bonael kkyupiteu hwasareul Geureohge dagaon gijeokeui seonmul gateun geudael saranghae Yeongwonhi hamkkehaejwo Everyday loving me saranghae Just Be My Love English Version : Since when is it, You come into my heart My heart keep thumping even for your little smile For along time, I’ve been waiting for this fate like love It’s you, I know it. Oh~ That my love is you You’re like a cotton candy that melting my heart all day. You’re like rainbow that coming dazzlingly into my heart Will you whispered me with your sweet voice That from the beginning your heart everyday loving me too I love you just be my love. Why I keep laughing when i heard your playful voice When your two little eyes stare at me, I even trembling like this For along time, I’ve been waiting for this fate like love It’s you, I know it. Oh~ That my love is you You’re like a cotton candy that melting my heart all day. You’re like rainbow that coming dazzlingly into my heart Will you whispered me with your sweet voice That from the beginning your heart everyday loving me too I love you just be my love. Do you know? The day we fall in love like this Do you believe? The Cupid’s arrow sent from Heaven I love you who come like miracle’s gift Let’s be together forever. loving me everyday I love you just be my love

Enterprise portal Essay Example | Topics and Well Written Essays - 1000 words

Enterprise portal - Essay Example It is web based. The technology behind this portal is Ext JS 4.0. This a pure and interactive JavaScript application framework for developing robust web applications exploiting techniques such as DHTML, Ajax and DOM scripting. From the web pages’ source code, it is clear that it is interoperable with jQuery and Prototype. It includes an optional architecture that provides a model view controller style of code organization. The portal has an overall superb usability experience. This is because the pages are arranged in a solid methodology coupled with proper tools. Also, all the components of the portal are working properly and together. Users can at a single glance access the university news or events and other coursework pages. The diagram below shows the layout of the pages and the components of the portal. The homepage shows two main tabs i.e. ‘My page’ and ‘Student Centre’. Under the ‘My Page’ tabs, users can access their degree progress, the enrollment date, class schedules, and financial aid, view their tuition account and also access to e-mail addresses, To-Do and holds summary, university news and events. In general, all the pages fit into a unified visual design and the flow of interaction hence providing a seamless user experience. This provides an ability for ease customization of the layout. This kind of portal aggregates information from various sources in one convenient page. Therefore users accessing the portal can reach important information such as campus news, campus events, the student center, degree progress, class schedules, and financial aid and can also view their tuition account. Each of these pages have different data sources that have been aggregated together so as to build up the portal. Therefore, for one to manage the data portal, data can be viewed, sorted and data sources filtered. The other data sources that have been

Review and evaluate solutions for SMEs.for UK And also Saudi Arabia Dissertation

Review and evaluate solutions for SMEs.for UK And also Saudi Arabia - Dissertation Example To further underpin and analyse these research objectives, the researcher used the anti-positivism research philosophy and inductive research approach based on personal observations and analysis of the situation. Primary data were collected in the form of interviews conducted on the SMEs owners based in the UK and Saudi Arabia while surveys were conducted on the consumers of the above mentioned countries. A total of 18 survey question were asked along with six interview questions and six more questions on ascertaining solutions for SMEs. The primary data revealed that the acceptance rate of e-commerce is quite high in the UK compared to Saudi Arabia mainly because of the acceptance of the technology by the owners and consumers. Furthermore, the risk factor, investment cost, security concerns, and perceived perceptions deterred the overall acceptance of e-commerce in Saudi Arabia. Based on the findings of the primary and secondary research, it was concluded that e-commerce has great d egree of benefits but requires great skill and expertise to implement it. Solutions in the context of Saudi Arabia were identified in the form of implementing small technological tools like websites through WordPress and enhancing the business presence. TABLE OF CONTENTS Chapter 1.Introduction 4 1.1Introduction 4 1.2 Research Aim 5 1.3 Research Objectives 5 1.4 Research Questions 5 1.5: Background of the Research 6 1.6 Rationale for the Research Topic 7 1.7 Scope of the Research 7 1.8: Proposed Methodology 7 1.9: Outline of the Dissertation 8 1.10: Summary 09 Chapter 2.0 Literature Review 10 2.1: Introduction 10 2.2: E-commerce and its Emergence 10 2.3: Significance of E-Commerce 12 2.4: E-Commerce in the UK 14 2.5: Less Adoption of E-commerce by SMEs in the UK 20 2.6: E-commerce in Saudi Arabia 21 2.7: Less Adoption of E-commerce by the SMEs in Saudi Arabia 23 2.8: SMEs and E-commerce Barriers in the UK and Saudi Arabia 26 2.9: SMEs and Technological Challenges 28 2.10: SMEs Soluti ons in the UK and Saudi Arabia 30 2.10.1: Reasons for the Difference in E-commerce Solutions 35 2.11: Summary 37 Chapter 3.0 Research Methodology 38 3.1: Introduction 38 3.2: Research Philosophy 38 3.3: Research Approach 39 3.4: Data Collection Methods 39 3.5: Research Design 39 3.6: Sampling 40 3.7: Questionnaire Formulation 40 3.8: Data Analysis 42 3.9: Ethical Considerations 42 3.10: Pilot Study 42 3.11: Strengths and Limitations of the Methodology 43 3.10: Summary 43 Chapter 4.0 Analysis 44 4.1: Introduction 44 4.2: Survey Analysis 44 4.3: Solutions for SMEs Pertaining to E-commerce 57 4.4: Interview Analysis (Saudi SMEs Owners) 61 4.5: Interview Analysis (UK SMEs Owners) 62 4.6: Association between Surveys and Interviews 64 4.7: Association between Primary Research and Literature Review 65 4.8: Summary 66 Chapter 5 Evaluation of Findings 67 5.1: Introduction 67 5.2: Possible Conclusion 67 5.3: Relationship between Primary data and Literature Review 68 5.4: Accomplishment of Res earch Objectives 69 5.4: Overall Expectations 69 5.5: Opportunity for Re-writing 70 5.6: Summary 70 Chapter-6: Conclusion and Recommendations 71 6.1: introduction 71 6.2: Conclusion 71 6.3: Suggestion for Future Work 74 6.4: Recommendations for SMEs and Future Research 75 6.5:

Chinese Birth Control Policy and gender discrimination Research Paper

Chinese Birth Control Policy and gender discrimination - Research Paper Example On the other hand, opponents of this policy have criticized the legislatures claim, and they argue that this policy had violated human rights especially when married couples are forced to an perform abortion or forced to use birth control methods. Additionally, in its approach towards population control, Chinese government has been established to discriminate against women. For instance, a report released by a United Nations Agency indicated that nobody in China reports cases of sex selective abortions, prohibition of infanticide and abandonment of female infants (Goh 15). In the current world, China has the highest population of over 1.2 billion, or 20 percent of the world’s population (Goh 57). However, the ratio between male and female is 120 males to 100 female (Goh 57). As the Chinese population control remains a significant issue in the Chinese government, the search for demographic goals has overshadowed the needs and interests of women and girls. This has led to seriou s discrimination against women in offices, abuse by officials and civil servants, and use of physical violence against women (Thoma 24). For instance, in many Chinese communities, women and girls are forced to be sterilized or use contraceptives, as a birth control method. ... ited for a number of significant achievements such as its international influence, huge and powerful military, its role in the free-market capitalism, and its growing prosperity. However, the issue of â€Å"One-Child policy†, which it introduced in the last three decades, still remains as a controversial issue, in the Chinese government. Communist Party officials insisted that they had to check population growth rate, and reduce the population to 1.2 billion by the year 2000 (Thoma 9). In 1980, the party officials also announced that several couples will not be allowed to have more than one child, with the exception of some few individuals. Earlier in 1949, after decades of war, unrest and epidemics, which were perceived as economic boom, Mao Zedong claimed â€Å"Even if China’s population multiplies many times, she is fully capable of finding a solution; the solution is production† (Thoma 43). Mao’s main motive was that a larger population was a necessity for a modern industrialized state. After some years of economic growth and prosperity, Chinese legislatures realized that the growing population was almost overtaking the country’s food supply. In 1955, several political leaders, led by Deng, reversed Mao’s claim, and vigorously campaigned to promote birth control. In 1962, a massive famine hit China, and over 30 million people were pronounced dead. This made political leaders to intense their campaign for population control, and between 1970 and 1976, the China’s population had dropped by half the initial population (Thoma 56). China’s â€Å"One-Child† Policy In the aftermath, a policy that required married couples, especially from Han community, to give birth to one child was introduced. This policy, however, exempted ethnic minorities. Under the

Administrative corruption Research Paper Example | Topics and Well Written Essays - 750 words

Administrative corruption - Research Paper Example Lastly, the paper will explore the consequences of corruption and ways to deal with these consequences. Nevertheless, this essay focuses on presenting a discussion regarding administrative corruption in terms of types, cause, effects, and consequences. Definition According to Myint (3) corruption in its basic form regards to a form of dishonesty or fraudulent behaviors, by people in power, which may involve bribery, bribery, nepotism, extortion, embezzlement, and favoritism or involvement in actions that make people to be morally depraved. Types One of the forms of corruption is bribery that receives a substantial share of references, whereby people a bribe as money or favors for influencing a public official and it is in form of fixed sum, percentage of contracts favor in money in kind that is given to a state official. It also related to the bribe given to a state official to make a contract on behave of the state or business with a distribution of the benefits to the companies or the clients. The other type of corruption is nepotism that occurs when the administrative offices favor their relatives or close friends for a position in organization; especially if they hold a high position that involves decision making. This form of corruption is natural to human beings, whereby they can give preferential treatment to their family members and friends. For example when a student is a relative to the principal and the teachers are reporting low marks in subjects he is taking, the principal can change the low marks to high marks, thus falling a victim of the temptations of nepotism. The other example of corruption involves police receiving of bribe from corrupt individuals to earn a favors by breaking the law, fencing stolen goods and others like extortions by police officers. Police may also engage in violation of individuals rights either by use of excessive physical force which is brutality, discriminatory arrest, or verbal harassment. Causes The first cause of c orruption is increases in the level of poverty in the society, whereby only the rich are favored, while the poor continues to sail in their boat of thrifty (Myint, 5). Apparently, this hinders them from enjoying their rights as citizens of a given country. Therefore, it becomes extremely complicated when it comes to dealing with the corruption in the in various administrative departments. For instance, police may receive bribes from public transport vehicles where by ignoring the vehicles (Myint, 6). They do not arrest those drivers that are over speeding, this being one of the main causes of accidents. The other cause of corruption has also been evident through effects of political influence on administrative officers with differentiated political affiliations (Myint, 8). Certain politicians manipulate the some administrative officers in order to achieve their inclinations by using bribes, threats and nepotism; thus, politicians and leaders have increased ability to perpetrate corr uption in the society, and this has negative impact on members of the society. Effects Corruption in organizations has economic effects on the community relating to categorization of being major or minor, though both of them have a serious impact on the individual community. Corruption results to depletion of resources or the national wealth, thus taking the responsibility for the increase in the cost of commodities, funneling of scarce public resources, leading to uneconomic projects at the expense of the need projects by the public such as schools, hospitals and improvement of infrastructure in the society, and it also contributes to misallocation of resource, conversion of

Comment on three minor characters such as Maria, Sir Toby, Sir Andrew, Essay - 1

Comment on three minor characters such as Maria, Sir Toby, Sir Andrew, or Feste. Why is each one important in the play - Essay Example Firstly, when the character of Sir Toby is taken into consideration, it is clear that it (the character) has been created for the purpose of humor. But here, it needs to be specifically highlighted that this character is a one having negative shades. Sir Toby resides in the house of his niece, even though he is in no way entitled to do so. Also, he treats all servants of the household in an extremely abusive manner. As a matter of fact, Sir Toby believes in using people for meeting his own interests. This is evident not just by the fact that he makes the home of his niece as his permanent residence, but also by the way in which he interacts with Sir Andrew, another comical character of the play. On one occasion in the play, Sir Toby states â€Å"What a plague means my niece, to take the death of her brother thus? I am sure cares an enemy to life.† These lines vividly focus on the fact that he has no sympathy for his niece, who is grieving the death of her brother. The fact tha t this focuses on his inhuman nature warrants no special mention. In another situation of the play, Sir Toby is unhesitant while remarking â€Å"With drinking healths to my niece: Ill drink to her as long as there is a passage in my throat and drink in Illyria: hes a coward and a coystrill that will not drink to my niece till his brains turn o the toe like a parish-top. What, wench! Castiliano vulgo! for here comes Sir Andrew Agueface.† Even a superficial reading of these lines is enough to convince anyone that, Sir Toby believes solely in drinking and making merry, even at others’ expense! Likewise, there are numerous examples in the play that stress on the negativity of Sir Toby’s character. (1) (2) Next, the focus needs to move on to the character of Maria, who is another member of Olivia’s household. In fact, it is in no way an overstatement in maintaining that the character of Maria is very much similar to the one of Sir Toby, having all the related negative traits.

Answer the Q Case Study Example | Topics and Well Written Essays - 500 words - 1

Answer the Q - Case Study Example Thus, both these aspects affect the people in economic terms by hampering their earning opportunities (U.S. Bureau of Labor Statistics., â€Å"Employment Situation†). Cyclical unemployment can be estimated to be very difficult to overcome in comparison to other types of unemployment. It is very difficult to overcome as it encompasses with large numbers of candidates who are willing to work, but are unable to get a proper employment. Cyclical employment is prevelant in almost every country whereby people with proper talents and potentials are unable to find a suitable job (U.S. Bureau of Labor Statistics., â€Å"Employment Situation†). While calculating the unemployment rate, all the factors relating to unemployment of different age groups and both the genders are taken into consideration with the help of separate calculations. It would be benficial if the unemployement rate, as a whole, is calculated for deriving the exact rate of unemployment rather than basing the calculations on different aspects that may include different reasons for unemployment among different age groups and genders who are unemployed. For creating more job opportunities in the US, the country would need to improve its economic stability. It is only then that the country can be able to provide better employment opportunities to the deserving candidates. If the nation can increase its profitability by way of different business investments and other commercial associations, the nation would be able to curb almost all the issues related to unemployment to a very large extent. There are numerous issues that can be observed as related with the unemployment levels in the US. Recession can be considered to be one of the primary reasons for high rate of unemployment in the US. Recession is often acquainted with contraction in the investment and spending approaches taken by businesses which further lead to unemployment within the nation (U.S. Bureau of Labor Statistics.,

Australian Property Law and Lease Contracts Essay

Australian Property Law and Lease Contracts - Essay Example In this regard, what Larry will be banking on is his ability to convince a court of law that Tom acted either against the law or against the agreement. In terms of the agreement between Larry and Tom, it can be proven, albeit not beyond doubt, that Tom knew all too well that he was breaching the contract. This can be evidenced by the fact that he had tried to ask Larry to allow him to change the property before altering its look. Tom acted in a way that is less than legally acceptable by setting up the meeting to discuss the matter and then choosing to go on with the repair work even before actually meeting with Larry. For this reason, Tom is in breach of the agreement between him and Larry and that shows that he had motive and intension to ignore the agreement. Apart from ignoring the agreement of the lease, Tom is also in contempt of law for the law does outlines clearly that such repairs to a leased property must not reduce the value of the property. While the law does protect the lessee from being forced to pay for any damages caused by such repairs, this must only happen within the provision of the law, which clearly stipulates that such repairs are not to be carried out, unless with an express permission by and from the owner of the property related to the case. Does Larry have the right to be compensated for the financial loss?The damages would not be limited by section 112 of the constitution unless Tom can prove himself not guilty of the breaching the contract.... This can be evidenced by the fact that he had tried to ask Larry to allow him to change the property before altering its look. Tom acted in a way that is less than legally acceptable by setting up the meeting to discuss the matter and then choosing to go on with the repair work even before actually meeting with Larry. For this reason, Tom is in breach of the agreement between him and Larry and that shows that he had motive and intension to ignore the agreement. Apart from ignoring the agreement of the lease, Tom is also in contempt of law for the law does outlines clearly that such repairs to a leased property must not reduce the value of the property. While the law does protect the lessee from being forced to pay for any damages caused by such repairs, this must only happen within the provision of the law, which clearly stipulates that such repairs are not to be carried out, unless with an express permission by and from the owner of the property. Does Larry have the right to be comp ensated for the financial loss? The damages would not be limited by section 112 of the constitution unless Tom can prove himself not guilty of the breaching the contract. Because the lessee did not act in accordance with the same section of property law by making repairs that were, against the spirit and letter of section 112, bound to not only significantly change the leased property but also to reduce its value, regardless of how much the reduction was, this means that therefore any further damages that can be directly associated by this act can be said to have been caused by Tom. This means that the lessee will not and must not be protected by section 112

How 'In the current environment knowledge and its effective management Essay

How 'In the current environment knowledge and its effective management are central to gaining competitive advantage' Discuss - Essay Example gement; for example, as Miller and Shamsie (1996) have shown in the case of the film industry, it is knowledge based resources in the form of production and financial knowledge which have boosted financial performance in an unpredictable global environment. The availability of specialized as possessed by a Company can help it to not only attain and sustain a competitive edge in the marketplace. According to Nonaka (1998), the uncertainty in the global environment means that the only aspect that is guaranteed to always provide a competitive advantage to a firm is knowledge; hence knowledge management through outsourcing is an organizational tool to achieve innovation and competitiveness. According to Quinn et al (1996), managing professional intellect is the key to value creation and profitability for most companies, especially within the framework of technology, which has created new rules and opportunities for organizational design. The traditional approach to knowledge is that it may be used freely by everyone without limitations. According to von Krohg et al (1994), knowledge is that which enables an individual to interpret and give meaning to the information he receives. However, they also argue that knowledge is subjective and is therefore linked to the group of individuals who are generating it. Therefore such information may be confined to a particular area or Company because of the inherent complexity of the information or because individuals are unwilling to codify the knowledge and present it in a format that can be shared with others. Nonaka and Takeuchi (1995:6) describe codified knowledge as something that is formal and systematic, which may be expressed in a number or words form and may be easily communicated because it is in the form of information – for example hard data or scientific formulae. Therefore, such information can easily be communicated to others. However, there may be certain kinds of knowledge which cannot be easily communicated,

The Social Security solution Essay Example for Free

The Social Security solution Essay The plan does not affect current retirees and those nearing retirement benefits for those now 55 or older would be untouched. Neither would it increase the retirement age above current law, increase payroll taxes or reduce annual cost-of-living adjustments (COLAs), now or in the future. We save Social Security by making two fundamental changes to the system for those now under 55. First, this plan changes the way first-time benefits will be calculated. These benefits now rise with overall wage growth. Under my plan, growth in initial benefits would be linked to the consumer price index. Initial benefits would still rise over time, only at a slower rate. Instead of rising 20 times over the next 75 years, they will increase by a factor of 10. Switching from wage indexing to price indexing will eliminate the unfunded liability of the Social Security system and allow us to avoid increasing the payroll tax for young workers. At the same time, future workers could count on receiving their benefits. Second, workers currently contribute 6. 2% of their wages to Social Security. My proposal allows workers under 55 the option of establishing their own personal savings accounts. Contributions into these accounts would range from 3. 5% of wages for low income workers to 1% for those at high income levels. Workers who choose to contribute to these accounts would have a variety of investment options and could withdraw proceeds upon retirement. But as they will be paying less into Social Security, their Social Security benefit will be slightly reduced. The basic Social Security benefit will be reduced by 25 cents on the dollar for each dollar they receive from their personal savings account. Nonetheless, the private investment account option should offer most recipients the opportunity for greater returns than Social Security alone could generate. Yes, we are asking some in the baby boom generation to insure the solvency of Social Security by making a sacrifice in terms of accepting a slightly lower initial benefit. An average 45-year-old male, for example, would receive about 1. 7% less under my plan, but look what happens in return. First, he is assured of receiving benefits because the solvency of Social Security is assured. More important, his children will receive far more in benefits. Under my plan a 25-year-old male who takes advantage of the personal savings account option should receive 19% more in benefits than promised under the existing system, based on historical averages for conservative investments. Todays retirees and those nearing retirement will receive their benefits just as they expected. Younger workers can not only count on receiving benefits, they will not have to worry about the prospect of working longer hours and paying increased payroll taxes that would otherwise be needed to keep the current system afloat. If they take advantage of the personal savings account option, theyll have more control over their own retirement resources and the opportunity for greater overall benefits than under our current Social Security system-even if it could pay all their promised benefits. Finally, and most important, my plan is honest and realistic. The problems facing Social Security have built up for so long and become so mammoth that everyone must realize they cannot just be wished away. This plan makes clear the costs and benefits, and it avoids false promises. If we are truly concerned about saving Social Security, there is no better plan than this one and no better time to start than today. If we face the challenge now, we can provide for our retirement security without sacrificing our childrens and grandchildrens standard of living. References Achenbaum, W. A. (1986). Social Security: Visions and Revisions. New York: Cambridge University Press Adams, P. (1990). Children as contributions in kind: Social security and family policy. Social Work, 35: 492-498. Buell, J. (1999). Avoiding generational war. Humanist, 59: 32-34. Hudson, R. (1999). The role of government in a society for all ages. Social Work, 24: 155-161. Kingston, E. R. and Schulz, J. H. (1997). (Eds. ) Social Security in the 21st Century. New York: Oxford University Press.

Non-Conventional Energy Resources

Non-Conventional Energy Resources India is a country rich in natural resources as well as in population. In order to cater to the needs of ever increasing population, we have to conserve our natural resources by utilizing them carefully. Energy resources are considered to be the most needed resources for the existence of mankind. The conventional energy resources like gas, oil and coal are used everywhere starting from the household chores to industrial activities. As the conventional resources are subject to depletion nature and cannot be regenerated immediately, there is a rummage around for alternative sources of energy. The government of India has recognized the need for the development and promotion of non-conventional energy resources like solar energy, wind-energy, bio-mass energy etc to conserve conventional resources. Establishment of Non conventional Energy Development Corporation of Andhra Pradesh Limited (NEDCAP) is a milestone in this endeavor. The article highlights the importance of non-conventional en ergy resources and the role of NEDCAP in promoting these sources and discusses the various sources of non-conventional energy and highlighted the efforts of NEDCAP in conservation of conventional sources of energy. *Associate Professor Head, Dept. of Management, Auroras PG College, Hyderabad and can be reached @ [emailprotected] **Assistant Professor, Dept of Business Administration, PVP Siddartha Institute of Technology, Vijayawada and can be reached @ [emailprotected] Introduction The conventional energy resources are continuously registering a diminishing balance with the population explosion and industrialization-taking place all around the world. India is the second largest in the world in the statistics of population and considered to be sixth in the consumption of energy as per the study conducted by the Government of A.P. In view of the existence of a large gap between the requirements of the population and the availability of the conventional sources of energy there is a need for the development of a sustainable resource based alternative for the conventional energy resources. The conventional energy resources are the natural resources like coal, oil and gas. With the rapid developments taking place in the industrial sector the need for energy is also increasing constantly. It has become inevitable to supplement the exhaustible resources with renewable resources to cater to the needs of the future generations effectively. Fortunately, India is gifted wi th large amount of sustainable non-conventional energy resources like solar power, wind and biomass along with small hydro power and industrial and domestic wastes. These resources are natural, cost free, available abundantly and readily usable for the generation of energy in different forms. Moreover these are pollution free and hence can be used to produce clean form of energy without any wastage apart from being renewable. So there is a need for the development of non-conventional energy resources in the country. Non-Conventional Energy Resources As the demand for power and energy is increasing rapidly and depletion of natural resources is taking place with the same pace, the emergence of environmental friendly and pollution free non-conventional energy resources has become a viable alternative. The non-conventional energy resources like solar energy through thermal as well as photovoltaic systems, wind energy, bio mass, hydal energy and industrial and household wastes will help the economy to a great extent in enhancing the power generation capacity and energy needs of different sectors. The following is a brief presentation of the renewable sources of energy. Solar Energy: India has a locational advantage in receiving abundant radiant energy form the sun as it is located in the equatorial sun belt of the earth. Majority of the Indian continent is bestowed with clear sunny weather in all most 280-300 days of a year. Daily solar energy incident over India varies from 4-7 KWH per square meter depending on the region. Solar energy can be used in two ways: Solar Thermal Conversion: Conversion of solar energy into heat using devices of steel, copper, aluminum is called solar-thermal conversion. A solar thermal device captures and transfers the heat energy available in the solar radiation. The energy generated can be used for varied applications in the household and industrial sectors like water heating systems, air heating systems, cooking and other household utilities. Solar Photovoltaic Conversion: This is the conversion of solar energy into electricity using semi conductors and their hybrids to convert the solar energy into Direct Current form of electricity for the application of DC and AC. The electricity thus generated can be used to needs of home lighting, street lighting and running motor pumps etc. The direct current form of solar energy is a major technical consideration for SPV application. Wind Energy: The evolution of windmills to convert wind power into energy, using wind turbines dates back to the beginning of the century. Denmark was the first country to install the first windmill for the generation of electricity. Later many countries entered into the field of wind energy. India started operations during 1983-84. The technology involves generation of electricity using turbines, which converts mechanical energy from the wind mills and is mainly used for pumping water from bore wells, open wells etc .However, average wind speed is major technical consideration to harness wind energy depending upon the climatic conditions and geographical locations of the project. Bio mass and other Bio energy systems: Bio mass is yet another renewable source of energy with potential to generate power to the extent of more than 50% of the requirements our country. Indian economy is predominantly an agricultural based economy with the availability of huge quantities of biomass available in the form of husk, straw, shells of coconuts and of wild bushes etc. Bio mass resources include large quantities cattle dung and other organic wastes. The biomass resources can be used for production of thermal energy or electricity. It can also be used to produce gas that may be used for combustion and to run gas engines. Small Hydro Power Hydropower is tapped from running waterfalls, canals and other water streams containing relatively small quantities of water but with some force of falling. The force of falling and flowing water can be converted into electricity by using turbines. This is a cheaper and abundant source on energy in our country. It is estimated that nearly 15,000 MW of power can be generated with the potential of the small hydro projects in the country. This power can be used to meet the requirements of the vicinity areas of the water streams like agro processing and milling. Industrial and other Wastes: These projects utilize the municipal and industrial wastes which has a problem for their disposal. The cleanliness of urban and industrial areas are achieved by utilizing these wastes as raw material to generate power. Wastes from the household, agricultural and industrial sectors are utilized to produce electricity. Industrial wastes from sago manufacturing units; sugar manufacturing units, poultries and others can be effectively used to produce power. This is a source of cheaper and renewable energy source available in India. Production of gases can also be undertaken using the wastes. Government Initiatives in Conservation of Energy Realizing the potential for energy from renewable sources, the government set up the Ministry of Non-conventional Energy Sources (MNES) in 1992, which is now called MNRE. The Prime Minister directly controls the activities of the ministry. MNRE activities include promotion of renewable energy technologies, creating an environment conducive to promote renewable energy technologies and assessment of renewable energy resources. Various sources of renewable energy are identified and policies are developed to supplement the conventional energy resources under the auspices of the ministry. Nodal agencies with different names have been established in different states to achieve the primary objective of supplementing the energy needs of the states. Non-Conventional Energy Development Corporation of Andhra Pradesh Limiited (NEDCAP) The nodal agency of Andhra pradesh is popularly called NEDCAP. Initially the name is Agro Pumpsets Implements Ltd., (APIL) for implementing non-conventional energy programmes sponsored by both the State and Central Governments. The corporation was incorporated on 21.10.1969 and was renamed as NEDCAP on 10-5-1986. The primary objectives of the Corporation are To survey, develop and implement renewable energy programmes of the State and Central Governments. To generate electricity through renewable sources like wind and solar energy on a decentralised manner. To conserve the sources of energy in rural areas. To import and adopt viable technology and machinery in the areas of Non-Conventional energy sources and ensures post installation service. To impart training and to promote research and development in the field of Non-conventional energy sources. To provide technical consultancy services in implementation of power projects through renewable energy sources. To achieve the above objectives NEDCAP has initiated many programmes in different areas of non-conventional energy sources. The programmes are continuously monitored and necessary support is extended to individuals, non-profit making organizations, commercial and industrial organizations working in various projects associated with renewable energy resources. The following are some highlights of the promotion measures initiated by NEDCAP. Promotion of solar energy Government of Andhra Pradesh has issued GOs under reference Nos. G.O.Ms.No.302 M.A. dated : 03.08.2004 and G.O.Ms.No.506 MA dated: 03-12.2004 of Municipal Administration Urban Development (M) Department making mandatory for installation of Solar Water Heating Systems at proposed construction of hospitals, nursing homes, hotels, guest houses, lodges and multi-storied buildings of stilt + 5 floors or 15 meters and above height provision shall be made in their plans. NEDCAP is taking all necessary initiatives in the implementation of the programme. It is providing subsidized loans with banks with concessional rates of interests. Type of Users Rate of interest applicable Domestic users 2% Institutional users not availing accelerated depreciation 3% Industrial and commercial users availing depreciation 5% Source: www.nedcap.gov.in Along with the provision of loans at concessional rates of interest, NEDCAP is also providing capital subsides for the organizations which are not availing the facility of soft loans depending on the type of the organization and the area used for collecting the solar energy. The subsidies are Rs. 1100 per square meter of the collector area for registered non-profit making organisations and Rs.825 per square meter of the collector area for registered commercial establishments. Further it is providing and incentive of Rs. 100 per square meter for motivators and agents working in the field of attracting potential buyers of the solar water heaters. Promotion of Wind energy Based on the studies conducted through wind monitoring exercise, it is found that the southern part of Andhra Pradesh has got wind potential for setting up of wind farms. The areas in Anantapur, Cuddapah, Kurnool and parts of Nellore and Chittoor district have been identified with relatively better potential sites to set up wind power projects. In the master plan to assess the potentiality in southern part of A.P. it is estimated that there is a potential of about 2100 MW capacity. NEDCAP has established 2.25 MW wind farm project at Kondamedapally, Kurnool dist. and 2.50 MW wind farm at Narasimhakonda, Nellore district under demonstration scheme of MNRE. To encourage investment and to promote wind power projects in Andhra Pradesh, the Govt.of Andhra Pradesh has announced a comprehensive policy and incentives to set up wind power projects in private sector. NEDCAP is the single window clearance agency to sanction projects up to 20 MW capacity in the State and so far 100.12 MW capacity of projects by 30 developers at Ramagiri, Kadavakallu, Tallimadugula in Anantapur District and on Tirumala Hills, Chittoor district, was commissioned. The total installed capacity is 107.37 MWs as on March, 2008. NEDCAP extends the following services to the wind farm developers to set up projects in private sector. Clearance of projects Selection of suitable sites for the proposed projects Providing data related to the speed of the wind and related parameters Guidance on suitable equipment needed , its erection and commissioning of the project Guidance on inter-facing of the project Co-ordination with the revenue department on the land allotment to the proposed projects Necessary technical assistance to the projects sanctioned and to the ones commissioned. A total of 0.25% of the project cost subject to a minimum Rs.1.50 lakhs / MW is payable to NEDCAP towards sanction fee of the project. Promotion of Biomass utilization After identifying the abundant availability of bio mass in the state of Andhra Pradesh NEDCAP has started implementing the Biogas programme since 1982-83. The initial stages of implementing the programme, 4 cum 6 cum capacity KVIC model biogas plants were erected. It has been observed that KVIC models of biogas plants are comparatively associated with high initial costs along with periodical maintenance. Since, 1990-91, the Corporation is promoting the Deenabandhu model as it is less expensive and more efficient. The programme gained momentum and the same model is continued. The Corporation till now has installed around 2.50 lakhs biogas plants in the state so far. Under the biomass programme rural energy programmes are designed and implemented. Rural Energy Programmes Sl.No. Description Nos. Installed 1 Family Size Biogas Plants for cooking 2.8 Lakhs 2 Improved Chulhas 27.28 lakhs Source: www.nedcap.gov.in National Project on Biogas Development Basing on the studies conducted and on the success of the plants already installed in Andhra Pradesh, there is huge demand/potential for the establishment of Biogas Plants in Andhra Pradesh. The estimated potential of family size biogas plants is 10.90 lakhs. So far 2.84 lakh family-size biogas plants have been installed in the state. Improved Chulhas The estimated potential in Andhra pradesh is 95 lakhs. Since 1984-85 the achievement is 27.03 lakhs. Presently, the programme is being undertaken with State Govt. assistance. Promotion of Industrial waste based Projects NEDCAP is authorized by the A.P. State Government vide. G.O. Ms. No. 253, E F (RES) Department, dated 15-11-94 to sanction the Municipal Solid Waste/Industrial Waste based Power projects of capacity up to 20 MW. Andhra Pradesh is having a number of Industries which generate effluents. These effluents are to be treated to have value added products. The waste generated from Industries like sago, starch, palm oil, distilleries, dairy, vegetable wastes and poultry etc can be treated to generate Electricity. The following table presents the total capacity of the power generation projects undertaken in the industrial waste management area. i) Municipal Solid Waste Projects 107 MW ii) Municipal Liquid Waste 16 MW Total 123 MW iii) Industrial Waste Projects 135.0 MW Source: www.aponlineltd.org It is estimated that there is a huge potential of 40 MW from municipal solid wastes in the cities of Hyderabad, Vijayawada, Visakhapatnam, Guntur. Two projects aggregating to a capacity of 12.6 MW are under implementation at Hyderabad and Vijayawada cities. It is estimated that there is still an untapped potential of 135 MW from industrial wastes including poultry, distilleries and others industries operating in the state. Out of this potential projects with a capacity of 1.50 MW have been commissioned. Small Hydro Power The activity of power generation from small hydro power has been transferred from AP TRANSCO wing which was previously known as APSEB to NEDCAP vide G.O.Ms.No.37 dated 01-02-1999 of Energy (Power I) Department, Government of AP. The assessed Hydro Power potential is 1000 MW (approx). The status report on Small Hydro Power projects is shown in the table given below. Status of small hydro power projects as on 31-03-2008 S.No. Description No. of projects Capacity in MW 1 No. of projects sanctioned 47 146.603 2 No. of projects commissioned 31 92.353 3 No. of projects under progress 05 7.150 4 No. of projects Financial closure not completed 11 47.100 5 Detailed project reports referred to Irrigation Dept. for issuance of No Objection Certificate 125 305.500 Source: www.nedcap.gov.in The total no of projects sanctioned are 47in number with a capacity of 146.603MW. The capacity utilized so far is 92.353 MW through 31 projects commissioned under private sector participation. The number if Projects, which are in progress, is 16 with a capacity of 54.250 MW. The proposals and detailed project reports referred to Irrigation Department for issuance of No Objection Certificate are aggregating to a total capacity of 305.500 MW. Andhra Pradesh is one of the pioneering states in the country in encouraging the non-conventional energy based power projects. The State Government has authorized the nodal agency NEDCAP to sanction NCES based power projects of capacity up to 20 MW in private sector also along with the public sector participation. The cumulative installed capacity as on 31.10.2003 is 473.09 MW which is about 4.6 % of the total installed capacity in the state. During the year 2002-03, 1287.55 Mega Units of power was fed into the State grid which is 3.65 % of the total volume of power generated in the state. The Non Conventional Energy based power projects have the following advantages Environmental friendly and produce green power with less costs and free rawmaterial. Every KWH of power generated from NCES will eliminate 1 KG of Carbon emission into the atmosphere which is relatively very less when compared with conventional sources like coal, oil and natural gas. Non Conventional Energy Sources are abundantly available and are renewable with in no period of time. Low gestation period of the projects commissioned under the utilization of non-conventional sources. Also helpful in conserving the rapidly depleting reserves of fossil fuels. Helpful in creating rural employment and self employment opportunities Helps in improving the economic and living conditions of the rural population. Conclusion The importance of non-conventional energy resources is gaining momentum in the country as well as in the state. India is now one of the countries implementing various programmes on the utilization and promotion of non-conventional energy resources. Rightly identifying the need of the hour for the conservation of energy resources the Planning Commission of India in its Integrated Energy Policy Report (IEPR) has highlighted the need to develop domestic supply options and diversify energy sources. The projections of the report state that non-conventional sources may account for 5 to 6 per cent of Indias total energy mix by 2031-32. As the Nodal agency of the state of Andhra Pradesh, NEDCAP is taking all necessary initiatives to promote the usage of the renewable sources of energy like solar, wind, biomass, industrial wastes etc, as evident from the above discussion on various areas of non-conventional areas of energy. Private participation is also solicited in some of the areas like pow er generation and solar heating systems. To become more effective in the promotion, NEDCAP can also undertake promotional and publicity campaigns for individuals, NGOs, commercial and non-commercial institutions elaborating the importance of the conservation of the conventional sources of energy and the need for supplementing them with non-conventional sources. Finally it is aptly said that Save Nature and Enjoy the Future

Hydrogels for Wound Healing Applications

Hydrogels for Wound Healing Applications Abstract This chapter discusses about the hydrogels both natural and synthetic that can be used for wound healing applications. Also it discusses briefly about the various novel techniques that have been developed recently. Keywords: Hydrogels; Chitosan, Antimicrobial; Grafting; Blending; Wound dressing; Wound healing; Gene therapy, Stem cell therapy, Skin Engineering, pH and Thermosensitive polymers. 1 Introduction Healthcare is an essential aspect of human survival. So many biopolymers have generated interest in a number of biomedical applications. Wound management is one such area where management of cuts, ulcers, and sores needs dressings which help in promoting rapid wound healing in order to obtain both functional and cosmetic results. [45] There are different kinds of wound management products: staples or sutures, dressings or bandages, surgical sealants and adhesives, skin substitutes, and other biomaterials. [51] Human skin provides an effective barrier to microbial penetration and subsequent infection. However, once the wound has been developed in this barrier, the infection chances increases. In case of chronic wounds, the colonization and infection potential increases as the result of the presence of avascular eschar which provides an environment for the uninhibited growth of microorganisms. [89] The rate of infection is related to the type of wound, general wound care, and local health of the patient. [88, 90] For avoiding infection, good clinical practices are needed. The management of chronic wounds is a very costly practice and it also places an enormous drain on healthcare resources; studies have calculated the cost of wounds to the NHS to be about  £1bn a year. [166] So for lowering this cost such wound management products are needed that are more economical and effective. Out of all the above wound management products, here in this chapter we will discuss more about the wound dressings that will provide an optimal healing environment to the wound. A dressing is an adjunct used by a person for application to a wound in order to promote healing and/or prevent further harm. It is designed to be in direct contact with the wound, so it is different from the bandage in the manner that bandages are normally used to hold dressing in place. A wound is a break in the epithelial integrity of the skin and may be accompanied by disruption of the structure and function of underlying normal tissue. Wounds can be divided into four categories based on their appearance and stage of healing: Necrotic, sloughing, granulating and epithelializing wounds. [87] Wounds cause discomfort and are more prone to infection and other troublesome complications. [75] Some diseases like diabetes, ischaemia and conditions like malnourishment, ageing, local infection, local tissue damage due to burn leads to delay in wound healing. Infection is a major complication of burn injury and is responsible for 50-75% of hospital deaths. [76] Human skin has one of the greatest capacities to regenerate itself amongst all of the tissues in our body. It constantly replaces old cells with new cells, enabling it to repair itself when damaged. Wound healing is a complex-physiologic process, which consists of three overlapping phases: inflammatory, proliferative and remodeling phases. The normal healing response begins the moment the tissue is injured. As the blood components spill into the site of injury, the platelets come into contact with exposed collagen and other elements of the extracellular matrix. This contact triggers the platelets to release clotting factors as well as essential growth factors. During the inflammation process, neutrophils are the first leukocytes which come at the site of injury to rid it from bacterial contamination. Then, the monocytes and their conversion to macrophages initiate tissue repair by releasing a number of biologically active substances and growth factors that are necessary for the initi ation of tissue formation process. In the third process, fibroblasts proliferate and migrate into the wound space and started the deposition of the loose extracellular matrix. Endothelial cells grow into a wound simultaneously with fibroblasts and undergo angiogenesis. Finally, tissue remodeling takes place to reconstruct the basement membrane by the differentiation of keratinocytes as well as the formation of follicle cells. [43, 49, 50] A scar is an essential part of this natural healing process following any type of damage to the skin. This can occur after a surgical incision or the healing of a wound. As your body makes an effort to close an open wound and protect itself from infection, it replaces injured skin tissue with rapidly generated scar tissue. Scarring is slight when the damaged outer layer of skin is healed by rebuilt tissue. When we damage the thick layer of tissue beneath the skin, rebuilding is more complicated. Our bodies lay down collagen fibers (a protein which is naturally produced by the body) and this usually results in a highly obvious scar. A permanent reminder of the injury is left behind. So, a dressing that can induce scarless healing is needed. Historically, a dressing was usually a piece of material, sometimes cloth, but the use of cobwebs, dung, leaves and honey has also been described. However, modern dressings include gauzes, semipermeable films, low adherent dressings, gels, foams, hydrocolloids, alginates, hydrogels and polysaccharide pastes. Wound dressings are passive, active or interactive. Passive dressings simply provide cover while active or interactive dressings are capable of modifying the physiology of the wound environment. Interactive dressings include hydrocolloids, hydrogels, alginates, foam dressings and antimicrobial dressings. [17, 20, 85] Traditionally dry wound dressings are considered to be good for healing wounds i.e. the wound should be covered with gauze or left open. But it has been observed by Winter [191] that when wound is left open to air without any dressing, a scab i.e. a dry covering covers the wound and decreases the rate of epithelialization. On the other hand, if moist dressing is used in place of dry dressings scab will not form and rate of healing increases as moist dressings provide low oxygen tension which helps in wound healing, these dressings not only keep cells viable which enables them to release growth factors while maintaining contact between them and the healing tissues, but may also modulate or stimulate their proliferation, these dressings decrease the pain at rest, during ambulation and during dressing changes also moist environment allows rapid and efficient delivery of any added antimicrobial agent thus prevent the wound from infection. So, the dressings that create and maintain a mois t environment, however, are now considered to provide the optimal conditions for wound healing. 2 Requirements of an ideal wound care system These characteristics should be present in the ideal wound care system (a) it should be capable of maintaining a high humidity at the wound site, (b) it should be non-toxic, (c) non-allergenic, (d) it can be removed without causing trauma to the wound, (e) it should pe impermeable to bacteria, (f) Thermally insulating, (g) it should be soft to touch, (h) it should allow proper gaseous exchange, (i) it should be free from particulate and toxic product, (j) promote tissue reconstruction processes and (k) it should be cost effective. [20, 165, 177] Out of all the dressings hydrocolloids, alginates and hydrogels each one has its own advantages and limitations but hydrogels are best and have all the characteristics that are needed in an ideal wound dressing. All the above mentioned characteristics can be achieved in hydrogel wound dressings. 3 Hydrogels for Wound Healing Applications Hydrogels are natural or synthetic cross-linked polymers used in a variety of medical and biomedical applications. Hydrogels consist of a matrix of insoluble polymers with up to 96% water content enabling them to donate water molecules to the wound surface and to maintain a moist environment at the wound bed. They are used in the construction of contact lenses, drug-delivery vehicles, wound dressings and as physiological electrodes or sensors. [17] Examples of hydrogel include Aquaform, Intrasite, GranuGel, Nu-Gel, Purilon, Sterigel. These also have the ability to absorb a degree of wound exudate. They transmit moisture vapour and oxygen, but their bacterial and fluid permeability is dependent on the type of secondary dressing used. [20] Hydrogels swell or shrink in aqueous solutions due to the association, dissociation and binding of various ions to polymer chains. These systems may swell in water until an equilibrium state is reached and retain their original shape. The interactions responsible for water sorption by hydrogels include the process of hydration, which is connected to the presence of such chemical groups as -OH, -COOH, -CONH2, -CONH-, and -SO3H and the existence of capillary areas and differences in osmotic pressure. The forces that make hydrogel dissolution impossible are presence of covalent bonds between individual polymer chains, hydrophobic and electrostatic interactions. [46] These are hydrophilic polymer networks which may absorb from 10-20% (an arbitrary lower limit) up to thousands of times their dry weight in water. These may be chemically stable or they may degrade and dissolve. They are called ‘reversible, or ‘physical gels when the networks are held together by molecular entanglements, and/or secondary forces including ionic, H-bonding or hydrophobic forces. [13, 14, 15] Hydrogels are called ‘permanent or ‘chemicalgels when they are covalently-crosslinked networks as shown in 1. Hydrogels can be made by irradiation, freeze-thawing or chemical methods. Out of all the methods, irradiation is considered as a suitable tool for the formation of hydrogels as in this method there is easy control of processing, no need of adding initiators or cross-linkers which are harmful, and have the possibility of formation and sterilization in one step. But as everything has its own advantages and disadvantages this method also has a disadvantage which is hydrogels formed by this method have poor mechanical strength. Nowadays, Freeze thawing technique is generally used to prepare hydrogels having good strength, stability and no crosslinkers and initiators. But the main disadvantage is that the prepared hydrogels have opaque appearance and limited swelling and thermal stability. [120] In comparison to the traditional gauze therapy the application of a hydrogel seems to significantly stimulate wound healing. [11] Various natural and synthetic polymers having good biocompatibility are used to develop hydrogel wound dressing. These polymers include natural polymers such as alginate, chitosan, gelatin and collagen and synthetic polymers such as polyurethane, poly(ethylene glycol), polycaprolactone, poly vinyl pyrrolidone, poly(lactide-co-glycolide), polyacrylonitrile , poly(amino acid), etc. Table 1 below shows different hydrophilic polymers used to synthesize hydrogel matrices. Table 1 Hydrophilic polymers used to synthesize hydrogel matrices. [13] Hydrogels may be classified as homopolymer hydrogels, copolymer hydrogels, multipolymer hydrogels, and interpenetrating polymeric hydrogels. Homopolymer hydrogels are crosslinked networks of one type of hydrophilic monomer unit, whereas copolymer hydrogels are produced by the crosslinking of two comonomer units, one of which must be hydrophilic. Multipolymer hydrogels are produced by the crosslinking of more than three monomers. Finally, interpenetrating polymeric hydrogels are produced by the swelling of a first network in a monomer and the reaction of the latter to form a second intermeshing network structure. [46, 47] Also, it has been shown that the blending of a natural polymer with a synthetic polymer seems to be a good method for obtaining materials having required mechanical and thermal properties in comparison to pure components. It is also a simple method by which suitable shapes such as films, sponges and hydrogels can be obtained easily to realize a variety of biomedical devices. 2 shows healing is faster with the hydrogel dressing than with the gauze dressing. Wound area covered by hydrogel decreases faster with increasing healing period. On the contrary, the wound covered by gauze dressing reduces by only half a percent even after 14 days. [192] 3.1 Natural Hydrogels Natural polymers, such as chitin, chitosan, alginate, collagen, elastin, genipin, gelatin, cellulose etc. have been used for dressing wounds because they play an important role in the healing process. [47] Chitosan is a partially deacetylated form of chitin. Chitin as BeschitinÃ’, Unitika, is also commercially available as dressing in Japan. [28] But as far as chitosan is concerned it is biocompatible, biodegradable, haemostatic, fungistatic [54] and non-toxic and can be successfully used as gels, films, fibres etc. This polymer also show antibacterial properties and possess good wound healing properties. [60, 61, 62] It has many applications as wound dressing, drug delivery device and as scaffold for tissue engineering. [63, 64] Some of the examples of wound dressings are given below which use chitosan as one of the biomaterial. Asymmetric chitosan membranes have been developed by using immersion-precipitation phase-inversion method. [123, 124, 125] These asymmetric chitosan membranes are homogeneous and have porous structure. This membrane was prepared by preheating casted chitosan solution in oven for different time periods for dry phase separation and then immersed in to coagulant tank for wet phase separation and were subsequently freeze-dried. The skin layer acts as the rate controlling barrier for the release of drug and the porous layer provide mechanical support to the skin layer. The water vapor transmission rate, gas permeability, PBS solution absorption, in-vitro degradation, cell culture, bacterial penetration and wound healing test of this dressing were carried out. These membranes are effective in controlling evaporative water loss, showed excellent oxygen permeability and also antibacterial in nature. These are also found to be an urgent hemostat. In another study, silver sulphadiazine was inc orporated as an antimicrobial agent to this asymmetric dressing. The release behaviour of both silver and sulphadiazine ions were studied and found to be significantly different from one another. Silver ions displayed a slow release behavior while sulphadiazine ions exhibited burst effect on first day of the drug release and then slowly tapered off. It is because of the interaction of silver with amino group of chitosan leading to its slow release throughout whereas, as the sulphadiazine ions were free to diffuse through the membrane to reach the wound site thus they showed a burst release. The membranes were further found effective against P. aerugniosa and S. aureus. In one of the papers, novel wound dressings were formed that composed of chitosan film and Minocycline Hydrochloride (MH) and commercial polyurethane film (Tegaderm) as a backing. It is also a useful formulation for the treatment of severe burn wounds. Water vapor and oxygen can permeate the Tegaderm film but water cannot. The tegaderm film support the polymer membrane. [126] In one of the studies, a silver nanocrystalline chitosan (SNC) wound dressing composed of nano-silver and chitosan was constructed by self-assembly and nanotechnology and used for treating deep partial-thickness wounds. In this, sterility and pyrogen testing were performed to ensure biosafety. These dressings promote wound healing and combat infection, and also decrease the risk of silver absorption in comparison with silver sulphadiazine (SSD) dressings. [127] There is also one more method of forming wound dressing composed of chitosan i.e. the formation of polyelectrolyte complex of gum kondagogu (GKG) and chitosan. This complex is formed by the electrostatic interaction between carboxyl group of gum and amine group of chitosan. This method is more advantageous as it avoids the use of organic solvents, chemical crosslinking agents and thus reduces the toxicity and undesirable side effects. In this, diclofenac sodium is used as model drug. The diclofenac loaded complex of gum kondagogu/ chitosan shows drug release which changes with change in pH. The drug release was higher at pH 6.8 as compared to pH 1.2, due to higher swelling of complex at higher pH. This holds a great potential as a natural polymer based delivery device for controlled delivery of drugs like diclofenac sodium for two reasons: (i) to reduce dosing frequency and (ii) lower the gastric toxicity. [152] Semi-interpenetrating polymer networks (SIPNs) composed of chitosan (CS) and poloxamer were prepared in order to improve the mechanical strength of CS. The WVTR was found to be 2508.2 ±65.7 gm−2 day−1, i.e. these can maintain a moist environment at wound site which enhance epithelial cell migration. Also, the in vitro assessment of SIPNs showed proper biodegradation and low cytotoxicity and in vivo is carried out on experimental full thickness wounds in a mouse model and found that the wounds covered with these were completely filled with new epithelium without any significant adverse reactions after 3 weeks. In one of the papers, a kind of surgical wound dressing, the chitosan-gelatin sponge wound dressing (CGSWD) having good antibacterial property is prepared. The in vitro test showed that the antibacterial effect of CGSWD on E. coli K88 is better than that of penicillin, and the effect on S. aureus is also better than that of cefradine. [137] One more wound dressing consists of two separate layers were prepared in which the upper layer is a swellable hydrogel material which can absorb exudates and also serve as mechanical and microbial barrier while lower layer is a chitosan acetate foam incorporated with the anti-microbial agent chlorherxidine gluconate. [183] The antimicrobial activity is checked by the Bauer-Kirby Disk Diffusion Test, inhibition zones can be clearly seen around the discs of chitosan acetate foams incorporated with chlorhexidine gluconate, in culture plates inoculated with either Gram-negative or positive bacteria showing that the dressing is antimicrobial in nature. Blending is a convenient and effective method to improve physical and mechanical properties of hydrogels. So modification of chitosan is done by blending with other polymers like cellulose. [178] In this, E. coli and S. aureus were used as the test bacteria to examine the antibacterial properties of chitosan, cellulose and chitosan/cellulose blends. The numbers of colony of these bacteria formed on the test membranes are shown in s 5 and 6. It was noted that the numbers of colony of all test bacteria formed on the chitosan/cellulose blend membranes were decreased with the increase of chitosan concentration. These blends are more effective against E. coli than that of S. aureus, as indicated by the lower colony unit. Thus these dressings are suitable to use as an antimicrobial wound dressing. Chitosan due to its structural properties has the ability to heal wounds without scar formation. [198] Since chitosan is composed of D-glucosamine, which is also the component present in the disaccharide subunits of hyaluronic acid, chitosan tries to structurally mimic hyaluronic acid and exerts similar effects. [197] It has been known that the fetal wound healing takes place without fibrosis or scar formation due to the presence of hyaluronic acid. [199] In one of the studies, Chitosan as a semi-permeable biological dressing maintains a moist environment and prevent the wound site from dehydration and contamination. In addition, digital colour separation analysis of donor site scars demonstrated an earlier return to normal skin colour at chitosan-treated areas as shown in 7. [196] Collagen is also a biopolymer that is used as a polymer for making wound dressing and drug delivery devices as it is biocompatible and biocompatibility of a material applied to wound tissue is a prerequisite for optimal wound environment and facilitation of the healing processes. A new collagen dressing with gentamycin or amikacin was prepared in one of the research work and these follow the basic requirement of antibacterial bandages. The dressing is composed of two collagen biomaterials—membrane and sponge—both possessing good tissue biocompatibility. These dressing released antibiotics slowly and show the antibacterial treatment in experimentally infected superficial wounds in mice. Thus, it can be used for the treatment of infected wounds in humans. [26] As discussed previously that both chitosan and collagen are excellent materials that can be used as wound dressing materials. So it has been seen that if both are used simultaneously then what will be the effect. It is found that the wound dressings composed of chitosan crosslinked collagen sponge (CCCS) enhance the diabetic wound healing. Collagen crosslinked with chitosan showed several advantages required for wound dressing, including the uniform and porous ultrastructure, less water imbibition, small interval porosity, and high resistance to collagenase digestion and slow release of FGF from CCCS/FGF. [138] Following moist healing concept, alginates which are able to absorb exudates from wound have become one of the most important materials for wound management. [52, 53, 54, 55, 56] In this particular field, the properties of alginate fibers are unparalleled in many respects. Alginate based products form a gel and effective in removing out of the wound on the contrary to traditional cotton and viscose fibres, which can entrap in the wound developing discomfort during dressing removal. [55] Also, the alginate fibres are non-toxic, non-carcinogenic, non-allergic, haemostatic, biocompatible, of reasonable strength, capable of being sterilized and easily processable. Sorbsanâ„ ¢ was first commercialized in 1981 and after that there were many dressings launched. The alginate fibers can be converted into wound dressings by using a number of textile processes. Because of its simplicity and also the high absorbency of the product, nonwoven is the main form of alginate wound dressings. [19] The antimicrobial action of alginate dressing can be seen as in 8 which shows the antimicrobial action of silver containing alginate fibers against E. Coli. There was 100% reduction in bacteria count within 5 hr after the fibers were placed in contact with solutions containing the bacteria. Sorbsan alginate fibers showed some antimicrobial activity while AquacelTM (made of carboxymethyl cellulose), does not show any antimicrobial effect. [18] Gelatin widely found in nature and is the major constituent of skin, bones, and connective tissue. Gelatin can easily be obtained by a controlled hydrolysis of the fibrous insoluble protein, collagen. [195] This is also used in number of biomedical applications like wound dressings. Hydrogel wound dressing from gelatin, oxidized alginate and borax were prepared and the composite matrix promotes wound healing because of alginate, has haemostatic effect of gelatin and is antiseptic because of borax. The water vapour transmission rate (WVTR) of the hydrogel was calculated and found to be 2686 ±124 g/m2/day indicating that this hydrogel can maintain a proper fluid balance at the wound site which helps in cell migration. 2 shows the loss of water vapour with time through the hydrogel when placed in a moisture rich environment. [119] Genipin has been used to crosslink chitosan membranes to control swelling ratio and mechanical properties. It increased its ultimate tensile strength but significantly reduced its strain-at-fracture and swelling ratio. It had significantly less cytotoxicity for human fibroblasts and slower degradation rate compared to the glutaraldehyde-crosslinked membrane. This genipin crosslinked chitosan membrane can be successfully used as a wound dressing. [132] Bacterial cellulose is a natural polymer consisting of microfibrils containing glucan chains bound together by hydrogen bonds. Bacterial cellulose with chitosan combines properties such as bioactivity, biocompatibility, and biodegradability of the two biopolymers and form an ideal material for dressing wounds. [66, 67] These are antibacterial and scar preventive in nature too. Since natural polymers have been considered limited in their applications for wound-dressing materials as their low mechanical properties and shortage of processing. So we move towards the synthetic polymers that can be used for wound healing applications. 3.2 Synthetic Hydrogels Synthetic polymers are also being used successfully in biomedical applications as one of the materials because of their wide range of mechanical properties, suitability for easily forming into a variety of different shapes, and low production costs. In an ideal dressing both the characteristics i.e. antimicrobial ability and moist healing environment should be present, so in order to prevent the wound from dehydration and bacterial penetration a new dressing composed of polyurethane is designed in such a way that the upper layer of the dressing is microporous (pore size Polyvinyl pyrrolidone (PVP) is one of the most widely used synthetic polymers in medicine because of its solubility in water and its extremely low cytotoxicity. Hydrogels prepared by radiation crosslinking of an aqueous solution of polyvinyl pyrrolidone (PVP) have been used as wound dressing. [21] These are biocompatible, reduces pain, easily replacable, permeable to oxygen, maintain moist environment at the wound site. Polyvinyl alcohol (PVA) is a well-known polymer because it is biocompatible and have required mechanical properties and polyethylene oxide (PEO) is a hydrophilic semicrystalline polyether which is biocompatible, non toxic, non polar, non antigenic and non immunogenic and is highly desirable in most biomedical applications requiring contact with physiological fluids. A hydrogel composed of PEO for wound dressing is prepared and PVA is added to give toughness to the hydrogel by electron beam irradiation and found that these hydrogels showed satisfactory properties for wound dressing that has been evaluated by creating wound on the back of the marmots. [157] The hydrogel gives a wet environment to wounds which causes faster healing compared with the gauze dressing with a dry environment. The weight of the hydrogel increases quickly at the earlier stages, up to 4 days, due to absorption of effusion produced from the wound as shown in Table 2. After that, the production of effusion from the wound ceases and the weight of the hydrogel decreases due to evaporation of the water in the hydrogel. This means that the healing of wound proceeds smoothly with time. The hydrogel can be peeled off easily from the wound at the time of removal. Table 2 Absorption of effusion from wound of dressing during healing. [157] The toughness of PEO hydrogel is improved by the addition of PVA and tensile strength is measured and found that as shown in 10 and 11, the tensile strength and elongation decrease with increasing dose because of the increase of crosslinking. Various synthetic polymers as discussed above are used for wound dressing applications. But the major problem with these materials is their biocompatibility characteristics are often unsatisfactory and their interaction with living tissues is a major problem. So a combination of both natural and synthetic polymers is the better option to make a hydrogel having biocompatibility and desired mechanical strength. 3.3 Blended hydrogels Since both the natural and synthetic polymers have their own advantages and disadvantages so a combination of natural and synthetic polymers can endow the optimal properties necessary for wound repair. [47] The combination of natural and synthetic polymers is used in the biomedical, bioengineering and biotechnology field nowadays because of their great potential. A blended hydrogel composed of polyvinyl alcohol/polyvinyl pyrrolidone and charcoal were prepared by single ‘‘freezing and thawing or two-step ‘‘freezing and thawing and ÃŽ ³-ray irradiation and applied as wound dressing. It is found that the absorption of S. aureus and P. aeruginosa by charcoal/PVA/PVP hydrogels was larger than those by PVA/PVP hydrogels, this is due to the absorption and attachment capability of bacteria by charcoal, this can be shown in 12 given below. [22] The most classical way of fabricating a CS based wound dressing has been to design an asymmetric composite structure. In this method, the Cotton fabric was coated with chitosan (CS) and polyethylene glycol (PEG) followed by freeze-drying. The outer dense layer helps in preventing the microbial passage across the dressing and provides a rate controlling barrier for water vapor permeation, while the inner porous layer provides a high surface area for the exudates absorption. For the absorption of wound exudates porosity is the prime requirement in a dressing. It has been found that these dressings have the porosity 54-70% and the pore size was in the range of 75-120 µm. [45] The increase in the PEG content in the blend composition led to an enhanced destabilization of pores, leading to an increase in the pore size with elongated morphology. There seems to be phase separation between the two components which is an important factor for the observed behavior of the porous structure. Cot ton fabric has been used as the support layer for the CS-PEG layer and leads to very thin and light weight structures. The structure of the dressing has been designed in such a way that it leads to the high porosity of the bulk structure. The thickness of CS coating plays an important role in the development of the porosity on the surface. The influence of the CS thickness on the surface morphology is presented in 13 given below. PEG addition to CS makes significant alteration in the surface morphology of this CS-PEG/cotton membrane (freeze-dried), henceforth known as CPC membrane. There is a distinct trend in the loss of inherent elongated porous structure in membranes and formation of the partially collapsed porosity takes place due to the PEG addition. This suggests that a very limited interaction between CS and PEG exists which is reflected in the observed surface morphology. It has been observed that higher the amount of PEG, the higher is the pore destabilization leading to larger pores. This is evident from the morphology of the CPC membrane at 50% PEG-20 content as shown in 14.45 On the above matrix, the addition of PVP and drug followed by coating on the cotton fabric and freeze drying of the coated matrix is also done. It has been found that the drug Hydrogels for Wound Healing Applications Hydrogels for Wound Healing Applications Abstract This chapter discusses about the hydrogels both natural and synthetic that can be used for wound healing applications. Also it discusses briefly about the various novel techniques that have been developed recently. Keywords: Hydrogels; Chitosan, Antimicrobial; Grafting; Blending; Wound dressing; Wound healing; Gene therapy, Stem cell therapy, Skin Engineering, pH and Thermosensitive polymers. 1 Introduction Healthcare is an essential aspect of human survival. So many biopolymers have generated interest in a number of biomedical applications. Wound management is one such area where management of cuts, ulcers, and sores needs dressings which help in promoting rapid wound healing in order to obtain both functional and cosmetic results. [45] There are different kinds of wound management products: staples or sutures, dressings or bandages, surgical sealants and adhesives, skin substitutes, and other biomaterials. [51] Human skin provides an effective barrier to microbial penetration and subsequent infection. However, once the wound has been developed in this barrier, the infection chances increases. In case of chronic wounds, the colonization and infection potential increases as the result of the presence of avascular eschar which provides an environment for the uninhibited growth of microorganisms. [89] The rate of infection is related to the type of wound, general wound care, and local health of the patient. [88, 90] For avoiding infection, good clinical practices are needed. The management of chronic wounds is a very costly practice and it also places an enormous drain on healthcare resources; studies have calculated the cost of wounds to the NHS to be about  £1bn a year. [166] So for lowering this cost such wound management products are needed that are more economical and effective. Out of all the above wound management products, here in this chapter we will discuss more about the wound dressings that will provide an optimal healing environment to the wound. A dressing is an adjunct used by a person for application to a wound in order to promote healing and/or prevent further harm. It is designed to be in direct contact with the wound, so it is different from the bandage in the manner that bandages are normally used to hold dressing in place. A wound is a break in the epithelial integrity of the skin and may be accompanied by disruption of the structure and function of underlying normal tissue. Wounds can be divided into four categories based on their appearance and stage of healing: Necrotic, sloughing, granulating and epithelializing wounds. [87] Wounds cause discomfort and are more prone to infection and other troublesome complications. [75] Some diseases like diabetes, ischaemia and conditions like malnourishment, ageing, local infection, local tissue damage due to burn leads to delay in wound healing. Infection is a major complication of burn injury and is responsible for 50-75% of hospital deaths. [76] Human skin has one of the greatest capacities to regenerate itself amongst all of the tissues in our body. It constantly replaces old cells with new cells, enabling it to repair itself when damaged. Wound healing is a complex-physiologic process, which consists of three overlapping phases: inflammatory, proliferative and remodeling phases. The normal healing response begins the moment the tissue is injured. As the blood components spill into the site of injury, the platelets come into contact with exposed collagen and other elements of the extracellular matrix. This contact triggers the platelets to release clotting factors as well as essential growth factors. During the inflammation process, neutrophils are the first leukocytes which come at the site of injury to rid it from bacterial contamination. Then, the monocytes and their conversion to macrophages initiate tissue repair by releasing a number of biologically active substances and growth factors that are necessary for the initi ation of tissue formation process. In the third process, fibroblasts proliferate and migrate into the wound space and started the deposition of the loose extracellular matrix. Endothelial cells grow into a wound simultaneously with fibroblasts and undergo angiogenesis. Finally, tissue remodeling takes place to reconstruct the basement membrane by the differentiation of keratinocytes as well as the formation of follicle cells. [43, 49, 50] A scar is an essential part of this natural healing process following any type of damage to the skin. This can occur after a surgical incision or the healing of a wound. As your body makes an effort to close an open wound and protect itself from infection, it replaces injured skin tissue with rapidly generated scar tissue. Scarring is slight when the damaged outer layer of skin is healed by rebuilt tissue. When we damage the thick layer of tissue beneath the skin, rebuilding is more complicated. Our bodies lay down collagen fibers (a protein which is naturally produced by the body) and this usually results in a highly obvious scar. A permanent reminder of the injury is left behind. So, a dressing that can induce scarless healing is needed. Historically, a dressing was usually a piece of material, sometimes cloth, but the use of cobwebs, dung, leaves and honey has also been described. However, modern dressings include gauzes, semipermeable films, low adherent dressings, gels, foams, hydrocolloids, alginates, hydrogels and polysaccharide pastes. Wound dressings are passive, active or interactive. Passive dressings simply provide cover while active or interactive dressings are capable of modifying the physiology of the wound environment. Interactive dressings include hydrocolloids, hydrogels, alginates, foam dressings and antimicrobial dressings. [17, 20, 85] Traditionally dry wound dressings are considered to be good for healing wounds i.e. the wound should be covered with gauze or left open. But it has been observed by Winter [191] that when wound is left open to air without any dressing, a scab i.e. a dry covering covers the wound and decreases the rate of epithelialization. On the other hand, if moist dressing is used in place of dry dressings scab will not form and rate of healing increases as moist dressings provide low oxygen tension which helps in wound healing, these dressings not only keep cells viable which enables them to release growth factors while maintaining contact between them and the healing tissues, but may also modulate or stimulate their proliferation, these dressings decrease the pain at rest, during ambulation and during dressing changes also moist environment allows rapid and efficient delivery of any added antimicrobial agent thus prevent the wound from infection. So, the dressings that create and maintain a mois t environment, however, are now considered to provide the optimal conditions for wound healing. 2 Requirements of an ideal wound care system These characteristics should be present in the ideal wound care system (a) it should be capable of maintaining a high humidity at the wound site, (b) it should be non-toxic, (c) non-allergenic, (d) it can be removed without causing trauma to the wound, (e) it should pe impermeable to bacteria, (f) Thermally insulating, (g) it should be soft to touch, (h) it should allow proper gaseous exchange, (i) it should be free from particulate and toxic product, (j) promote tissue reconstruction processes and (k) it should be cost effective. [20, 165, 177] Out of all the dressings hydrocolloids, alginates and hydrogels each one has its own advantages and limitations but hydrogels are best and have all the characteristics that are needed in an ideal wound dressing. All the above mentioned characteristics can be achieved in hydrogel wound dressings. 3 Hydrogels for Wound Healing Applications Hydrogels are natural or synthetic cross-linked polymers used in a variety of medical and biomedical applications. Hydrogels consist of a matrix of insoluble polymers with up to 96% water content enabling them to donate water molecules to the wound surface and to maintain a moist environment at the wound bed. They are used in the construction of contact lenses, drug-delivery vehicles, wound dressings and as physiological electrodes or sensors. [17] Examples of hydrogel include Aquaform, Intrasite, GranuGel, Nu-Gel, Purilon, Sterigel. These also have the ability to absorb a degree of wound exudate. They transmit moisture vapour and oxygen, but their bacterial and fluid permeability is dependent on the type of secondary dressing used. [20] Hydrogels swell or shrink in aqueous solutions due to the association, dissociation and binding of various ions to polymer chains. These systems may swell in water until an equilibrium state is reached and retain their original shape. The interactions responsible for water sorption by hydrogels include the process of hydration, which is connected to the presence of such chemical groups as -OH, -COOH, -CONH2, -CONH-, and -SO3H and the existence of capillary areas and differences in osmotic pressure. The forces that make hydrogel dissolution impossible are presence of covalent bonds between individual polymer chains, hydrophobic and electrostatic interactions. [46] These are hydrophilic polymer networks which may absorb from 10-20% (an arbitrary lower limit) up to thousands of times their dry weight in water. These may be chemically stable or they may degrade and dissolve. They are called ‘reversible, or ‘physical gels when the networks are held together by molecular entanglements, and/or secondary forces including ionic, H-bonding or hydrophobic forces. [13, 14, 15] Hydrogels are called ‘permanent or ‘chemicalgels when they are covalently-crosslinked networks as shown in 1. Hydrogels can be made by irradiation, freeze-thawing or chemical methods. Out of all the methods, irradiation is considered as a suitable tool for the formation of hydrogels as in this method there is easy control of processing, no need of adding initiators or cross-linkers which are harmful, and have the possibility of formation and sterilization in one step. But as everything has its own advantages and disadvantages this method also has a disadvantage which is hydrogels formed by this method have poor mechanical strength. Nowadays, Freeze thawing technique is generally used to prepare hydrogels having good strength, stability and no crosslinkers and initiators. But the main disadvantage is that the prepared hydrogels have opaque appearance and limited swelling and thermal stability. [120] In comparison to the traditional gauze therapy the application of a hydrogel seems to significantly stimulate wound healing. [11] Various natural and synthetic polymers having good biocompatibility are used to develop hydrogel wound dressing. These polymers include natural polymers such as alginate, chitosan, gelatin and collagen and synthetic polymers such as polyurethane, poly(ethylene glycol), polycaprolactone, poly vinyl pyrrolidone, poly(lactide-co-glycolide), polyacrylonitrile , poly(amino acid), etc. Table 1 below shows different hydrophilic polymers used to synthesize hydrogel matrices. Table 1 Hydrophilic polymers used to synthesize hydrogel matrices. [13] Hydrogels may be classified as homopolymer hydrogels, copolymer hydrogels, multipolymer hydrogels, and interpenetrating polymeric hydrogels. Homopolymer hydrogels are crosslinked networks of one type of hydrophilic monomer unit, whereas copolymer hydrogels are produced by the crosslinking of two comonomer units, one of which must be hydrophilic. Multipolymer hydrogels are produced by the crosslinking of more than three monomers. Finally, interpenetrating polymeric hydrogels are produced by the swelling of a first network in a monomer and the reaction of the latter to form a second intermeshing network structure. [46, 47] Also, it has been shown that the blending of a natural polymer with a synthetic polymer seems to be a good method for obtaining materials having required mechanical and thermal properties in comparison to pure components. It is also a simple method by which suitable shapes such as films, sponges and hydrogels can be obtained easily to realize a variety of biomedical devices. 2 shows healing is faster with the hydrogel dressing than with the gauze dressing. Wound area covered by hydrogel decreases faster with increasing healing period. On the contrary, the wound covered by gauze dressing reduces by only half a percent even after 14 days. [192] 3.1 Natural Hydrogels Natural polymers, such as chitin, chitosan, alginate, collagen, elastin, genipin, gelatin, cellulose etc. have been used for dressing wounds because they play an important role in the healing process. [47] Chitosan is a partially deacetylated form of chitin. Chitin as BeschitinÃ’, Unitika, is also commercially available as dressing in Japan. [28] But as far as chitosan is concerned it is biocompatible, biodegradable, haemostatic, fungistatic [54] and non-toxic and can be successfully used as gels, films, fibres etc. This polymer also show antibacterial properties and possess good wound healing properties. [60, 61, 62] It has many applications as wound dressing, drug delivery device and as scaffold for tissue engineering. [63, 64] Some of the examples of wound dressings are given below which use chitosan as one of the biomaterial. Asymmetric chitosan membranes have been developed by using immersion-precipitation phase-inversion method. [123, 124, 125] These asymmetric chitosan membranes are homogeneous and have porous structure. This membrane was prepared by preheating casted chitosan solution in oven for different time periods for dry phase separation and then immersed in to coagulant tank for wet phase separation and were subsequently freeze-dried. The skin layer acts as the rate controlling barrier for the release of drug and the porous layer provide mechanical support to the skin layer. The water vapor transmission rate, gas permeability, PBS solution absorption, in-vitro degradation, cell culture, bacterial penetration and wound healing test of this dressing were carried out. These membranes are effective in controlling evaporative water loss, showed excellent oxygen permeability and also antibacterial in nature. These are also found to be an urgent hemostat. In another study, silver sulphadiazine was inc orporated as an antimicrobial agent to this asymmetric dressing. The release behaviour of both silver and sulphadiazine ions were studied and found to be significantly different from one another. Silver ions displayed a slow release behavior while sulphadiazine ions exhibited burst effect on first day of the drug release and then slowly tapered off. It is because of the interaction of silver with amino group of chitosan leading to its slow release throughout whereas, as the sulphadiazine ions were free to diffuse through the membrane to reach the wound site thus they showed a burst release. The membranes were further found effective against P. aerugniosa and S. aureus. In one of the papers, novel wound dressings were formed that composed of chitosan film and Minocycline Hydrochloride (MH) and commercial polyurethane film (Tegaderm) as a backing. It is also a useful formulation for the treatment of severe burn wounds. Water vapor and oxygen can permeate the Tegaderm film but water cannot. The tegaderm film support the polymer membrane. [126] In one of the studies, a silver nanocrystalline chitosan (SNC) wound dressing composed of nano-silver and chitosan was constructed by self-assembly and nanotechnology and used for treating deep partial-thickness wounds. In this, sterility and pyrogen testing were performed to ensure biosafety. These dressings promote wound healing and combat infection, and also decrease the risk of silver absorption in comparison with silver sulphadiazine (SSD) dressings. [127] There is also one more method of forming wound dressing composed of chitosan i.e. the formation of polyelectrolyte complex of gum kondagogu (GKG) and chitosan. This complex is formed by the electrostatic interaction between carboxyl group of gum and amine group of chitosan. This method is more advantageous as it avoids the use of organic solvents, chemical crosslinking agents and thus reduces the toxicity and undesirable side effects. In this, diclofenac sodium is used as model drug. The diclofenac loaded complex of gum kondagogu/ chitosan shows drug release which changes with change in pH. The drug release was higher at pH 6.8 as compared to pH 1.2, due to higher swelling of complex at higher pH. This holds a great potential as a natural polymer based delivery device for controlled delivery of drugs like diclofenac sodium for two reasons: (i) to reduce dosing frequency and (ii) lower the gastric toxicity. [152] Semi-interpenetrating polymer networks (SIPNs) composed of chitosan (CS) and poloxamer were prepared in order to improve the mechanical strength of CS. The WVTR was found to be 2508.2 ±65.7 gm−2 day−1, i.e. these can maintain a moist environment at wound site which enhance epithelial cell migration. Also, the in vitro assessment of SIPNs showed proper biodegradation and low cytotoxicity and in vivo is carried out on experimental full thickness wounds in a mouse model and found that the wounds covered with these were completely filled with new epithelium without any significant adverse reactions after 3 weeks. In one of the papers, a kind of surgical wound dressing, the chitosan-gelatin sponge wound dressing (CGSWD) having good antibacterial property is prepared. The in vitro test showed that the antibacterial effect of CGSWD on E. coli K88 is better than that of penicillin, and the effect on S. aureus is also better than that of cefradine. [137] One more wound dressing consists of two separate layers were prepared in which the upper layer is a swellable hydrogel material which can absorb exudates and also serve as mechanical and microbial barrier while lower layer is a chitosan acetate foam incorporated with the anti-microbial agent chlorherxidine gluconate. [183] The antimicrobial activity is checked by the Bauer-Kirby Disk Diffusion Test, inhibition zones can be clearly seen around the discs of chitosan acetate foams incorporated with chlorhexidine gluconate, in culture plates inoculated with either Gram-negative or positive bacteria showing that the dressing is antimicrobial in nature. Blending is a convenient and effective method to improve physical and mechanical properties of hydrogels. So modification of chitosan is done by blending with other polymers like cellulose. [178] In this, E. coli and S. aureus were used as the test bacteria to examine the antibacterial properties of chitosan, cellulose and chitosan/cellulose blends. The numbers of colony of these bacteria formed on the test membranes are shown in s 5 and 6. It was noted that the numbers of colony of all test bacteria formed on the chitosan/cellulose blend membranes were decreased with the increase of chitosan concentration. These blends are more effective against E. coli than that of S. aureus, as indicated by the lower colony unit. Thus these dressings are suitable to use as an antimicrobial wound dressing. Chitosan due to its structural properties has the ability to heal wounds without scar formation. [198] Since chitosan is composed of D-glucosamine, which is also the component present in the disaccharide subunits of hyaluronic acid, chitosan tries to structurally mimic hyaluronic acid and exerts similar effects. [197] It has been known that the fetal wound healing takes place without fibrosis or scar formation due to the presence of hyaluronic acid. [199] In one of the studies, Chitosan as a semi-permeable biological dressing maintains a moist environment and prevent the wound site from dehydration and contamination. In addition, digital colour separation analysis of donor site scars demonstrated an earlier return to normal skin colour at chitosan-treated areas as shown in 7. [196] Collagen is also a biopolymer that is used as a polymer for making wound dressing and drug delivery devices as it is biocompatible and biocompatibility of a material applied to wound tissue is a prerequisite for optimal wound environment and facilitation of the healing processes. A new collagen dressing with gentamycin or amikacin was prepared in one of the research work and these follow the basic requirement of antibacterial bandages. The dressing is composed of two collagen biomaterials—membrane and sponge—both possessing good tissue biocompatibility. These dressing released antibiotics slowly and show the antibacterial treatment in experimentally infected superficial wounds in mice. Thus, it can be used for the treatment of infected wounds in humans. [26] As discussed previously that both chitosan and collagen are excellent materials that can be used as wound dressing materials. So it has been seen that if both are used simultaneously then what will be the effect. It is found that the wound dressings composed of chitosan crosslinked collagen sponge (CCCS) enhance the diabetic wound healing. Collagen crosslinked with chitosan showed several advantages required for wound dressing, including the uniform and porous ultrastructure, less water imbibition, small interval porosity, and high resistance to collagenase digestion and slow release of FGF from CCCS/FGF. [138] Following moist healing concept, alginates which are able to absorb exudates from wound have become one of the most important materials for wound management. [52, 53, 54, 55, 56] In this particular field, the properties of alginate fibers are unparalleled in many respects. Alginate based products form a gel and effective in removing out of the wound on the contrary to traditional cotton and viscose fibres, which can entrap in the wound developing discomfort during dressing removal. [55] Also, the alginate fibres are non-toxic, non-carcinogenic, non-allergic, haemostatic, biocompatible, of reasonable strength, capable of being sterilized and easily processable. Sorbsanâ„ ¢ was first commercialized in 1981 and after that there were many dressings launched. The alginate fibers can be converted into wound dressings by using a number of textile processes. Because of its simplicity and also the high absorbency of the product, nonwoven is the main form of alginate wound dressings. [19] The antimicrobial action of alginate dressing can be seen as in 8 which shows the antimicrobial action of silver containing alginate fibers against E. Coli. There was 100% reduction in bacteria count within 5 hr after the fibers were placed in contact with solutions containing the bacteria. Sorbsan alginate fibers showed some antimicrobial activity while AquacelTM (made of carboxymethyl cellulose), does not show any antimicrobial effect. [18] Gelatin widely found in nature and is the major constituent of skin, bones, and connective tissue. Gelatin can easily be obtained by a controlled hydrolysis of the fibrous insoluble protein, collagen. [195] This is also used in number of biomedical applications like wound dressings. Hydrogel wound dressing from gelatin, oxidized alginate and borax were prepared and the composite matrix promotes wound healing because of alginate, has haemostatic effect of gelatin and is antiseptic because of borax. The water vapour transmission rate (WVTR) of the hydrogel was calculated and found to be 2686 ±124 g/m2/day indicating that this hydrogel can maintain a proper fluid balance at the wound site which helps in cell migration. 2 shows the loss of water vapour with time through the hydrogel when placed in a moisture rich environment. [119] Genipin has been used to crosslink chitosan membranes to control swelling ratio and mechanical properties. It increased its ultimate tensile strength but significantly reduced its strain-at-fracture and swelling ratio. It had significantly less cytotoxicity for human fibroblasts and slower degradation rate compared to the glutaraldehyde-crosslinked membrane. This genipin crosslinked chitosan membrane can be successfully used as a wound dressing. [132] Bacterial cellulose is a natural polymer consisting of microfibrils containing glucan chains bound together by hydrogen bonds. Bacterial cellulose with chitosan combines properties such as bioactivity, biocompatibility, and biodegradability of the two biopolymers and form an ideal material for dressing wounds. [66, 67] These are antibacterial and scar preventive in nature too. Since natural polymers have been considered limited in their applications for wound-dressing materials as their low mechanical properties and shortage of processing. So we move towards the synthetic polymers that can be used for wound healing applications. 3.2 Synthetic Hydrogels Synthetic polymers are also being used successfully in biomedical applications as one of the materials because of their wide range of mechanical properties, suitability for easily forming into a variety of different shapes, and low production costs. In an ideal dressing both the characteristics i.e. antimicrobial ability and moist healing environment should be present, so in order to prevent the wound from dehydration and bacterial penetration a new dressing composed of polyurethane is designed in such a way that the upper layer of the dressing is microporous (pore size Polyvinyl pyrrolidone (PVP) is one of the most widely used synthetic polymers in medicine because of its solubility in water and its extremely low cytotoxicity. Hydrogels prepared by radiation crosslinking of an aqueous solution of polyvinyl pyrrolidone (PVP) have been used as wound dressing. [21] These are biocompatible, reduces pain, easily replacable, permeable to oxygen, maintain moist environment at the wound site. Polyvinyl alcohol (PVA) is a well-known polymer because it is biocompatible and have required mechanical properties and polyethylene oxide (PEO) is a hydrophilic semicrystalline polyether which is biocompatible, non toxic, non polar, non antigenic and non immunogenic and is highly desirable in most biomedical applications requiring contact with physiological fluids. A hydrogel composed of PEO for wound dressing is prepared and PVA is added to give toughness to the hydrogel by electron beam irradiation and found that these hydrogels showed satisfactory properties for wound dressing that has been evaluated by creating wound on the back of the marmots. [157] The hydrogel gives a wet environment to wounds which causes faster healing compared with the gauze dressing with a dry environment. The weight of the hydrogel increases quickly at the earlier stages, up to 4 days, due to absorption of effusion produced from the wound as shown in Table 2. After that, the production of effusion from the wound ceases and the weight of the hydrogel decreases due to evaporation of the water in the hydrogel. This means that the healing of wound proceeds smoothly with time. The hydrogel can be peeled off easily from the wound at the time of removal. Table 2 Absorption of effusion from wound of dressing during healing. [157] The toughness of PEO hydrogel is improved by the addition of PVA and tensile strength is measured and found that as shown in 10 and 11, the tensile strength and elongation decrease with increasing dose because of the increase of crosslinking. Various synthetic polymers as discussed above are used for wound dressing applications. But the major problem with these materials is their biocompatibility characteristics are often unsatisfactory and their interaction with living tissues is a major problem. So a combination of both natural and synthetic polymers is the better option to make a hydrogel having biocompatibility and desired mechanical strength. 3.3 Blended hydrogels Since both the natural and synthetic polymers have their own advantages and disadvantages so a combination of natural and synthetic polymers can endow the optimal properties necessary for wound repair. [47] The combination of natural and synthetic polymers is used in the biomedical, bioengineering and biotechnology field nowadays because of their great potential. A blended hydrogel composed of polyvinyl alcohol/polyvinyl pyrrolidone and charcoal were prepared by single ‘‘freezing and thawing or two-step ‘‘freezing and thawing and ÃŽ ³-ray irradiation and applied as wound dressing. It is found that the absorption of S. aureus and P. aeruginosa by charcoal/PVA/PVP hydrogels was larger than those by PVA/PVP hydrogels, this is due to the absorption and attachment capability of bacteria by charcoal, this can be shown in 12 given below. [22] The most classical way of fabricating a CS based wound dressing has been to design an asymmetric composite structure. In this method, the Cotton fabric was coated with chitosan (CS) and polyethylene glycol (PEG) followed by freeze-drying. The outer dense layer helps in preventing the microbial passage across the dressing and provides a rate controlling barrier for water vapor permeation, while the inner porous layer provides a high surface area for the exudates absorption. For the absorption of wound exudates porosity is the prime requirement in a dressing. It has been found that these dressings have the porosity 54-70% and the pore size was in the range of 75-120 µm. [45] The increase in the PEG content in the blend composition led to an enhanced destabilization of pores, leading to an increase in the pore size with elongated morphology. There seems to be phase separation between the two components which is an important factor for the observed behavior of the porous structure. Cot ton fabric has been used as the support layer for the CS-PEG layer and leads to very thin and light weight structures. The structure of the dressing has been designed in such a way that it leads to the high porosity of the bulk structure. The thickness of CS coating plays an important role in the development of the porosity on the surface. The influence of the CS thickness on the surface morphology is presented in 13 given below. PEG addition to CS makes significant alteration in the surface morphology of this CS-PEG/cotton membrane (freeze-dried), henceforth known as CPC membrane. There is a distinct trend in the loss of inherent elongated porous structure in membranes and formation of the partially collapsed porosity takes place due to the PEG addition. This suggests that a very limited interaction between CS and PEG exists which is reflected in the observed surface morphology. It has been observed that higher the amount of PEG, the higher is the pore destabilization leading to larger pores. This is evident from the morphology of the CPC membrane at 50% PEG-20 content as shown in 14.45 On the above matrix, the addition of PVP and drug followed by coating on the cotton fabric and freeze drying of the coated matrix is also done. It has been found that the drug