OPHTHALMIC NANOPARTICLES DRUG DELIVERY SYSTEMS
The transmission for visible light is 92%. The refractive index is 1.492 for PMMA. There are types that transmit UV rays, and types that absorb it almost completely, as a result of which sensitive dyes on painted surfaces behind are protected from fading. · Chemical Resistance PropertiesPMMA is resistant to aliphatic hydrocarbons, cycloaliphatic compounds, fats and oils, and also to dilute acids at temperatures of up to 60oC. Chlorinated aliphatic hydrocarbons, ketones, alcohols, ethers, esters, aromatics, petrol, spirit, nitrocellulose varnishes and certain plasticisers cause PMMA to swell or produce stress cracks. The resistance to weathering of PMMA is very good. Natural colour PMMA is crystal clear and has a high surface gloss. It can be produced in all colours, transparent and muted. Health and SafetyPMMA is odorless and tasteless and physiologically safe. USESPMMA or Acrylic is a versatile material and has been used in a wide range of fields and applications. Medical technologies and implantsPMMA has a good degree of compatibility with human tissue, and can be used for replacement intraocular lenses in the eye when the original lens has been removed in the treatment of cataracts. Historically, hard contact lenses were frequently made of this material. Soft contact lenses are often made of a related polymer, where acrylate monomers containing one or more hydroxyl groups make them hydrophilic. In orthopedics, PMMA bone cement is used to affix implants and to remodel lost bone. It is supplied as a powder with liquid methyl methacrylate (MMA). Although PMMA is biologically compatible, MMA is considered to be an irritant and a possible carcinogen.Pages: 1 2 3 4 [5] 6 7
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03.12.2009
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What Is SuccessWhat Is SuccessAuthor: Wadzanai NenzouAs human beings we go through life asking what success is? Because it is not an easy word to define, this question can be asked all through someones life.Success to some people might be gaining a degree from a university with prestige. To others, success may mean committing to another person with feelings so intense that they marry. Having a high paying job with many perks is to many people the meaning of success. So, what is success anyway? It is all of these things, and absolutely none of these things. |