" The drugs' levels of PMMA, a dangerous stimulant, were so high, one of VICE's sources claimed, that whoever manufactured them was either "completely idiotic" or "taking advantage of the fact that PMA and PMMA are cheaper to source than MDMA.
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Polymethyl methacrylate (PMMA) is used in the construction, automotive and electronics industries and known by brand names such as Plexiglas.
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PMMA, better known as Plexiglas, is the most widely used polymer in the human body—but it's not risk-free.
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After all, the frequent and sometimes lethal distribution of impure drugs has been well reported, whether it's PMA, PMMA or even actual concrete.
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The fine, silvery powder is made from a polymer called PMMA (poly-methyl methacrylate), which you might know better in its acrylic glass form, Plexiglas.
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The risk can be mitigated, but this will require astute engineering of various physical and chemical properties of the PMMA, including surface charge, morphology and adhesiveness.
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Dr. Mathiowitz's work has focused on what applications polymers like PMMA can have in the human body, and she previously worked on removable tattoo ink projects.
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A technique known as "bioplastia," for example, consists of injecting a liquid compound called PMMA into the body in order to permanently reshape a patient's features.
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" She said that limiting the amount of PMMA allowed wouldn't have stopped her: "I would have gone to four or five doctors, getting a little bit from each one.
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This substance, PMMA, grabbed headlines in 2014 when Andressa Urach, a runner-up in a Miss Bumbum beauty pageant, was hospitalized in septic shock following injections to build more voluptuous thighs.
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While many prospective patients are tempted by the cheap price tag, Mr. Steffen said the main allure of PMMA is the speed and relative ease with which it can be applied.
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The results are shocking: in one year alone, the injection of PMMA caused complications or deformities in nearly 17,000 patients in Brazil, according to a survey published by the association in 2017.
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Gas permeable and polymethylmethacrylate (PMMA) lenses are well known to become enveloped in tissue (patient thinks it fell out) only to appear as a lump in the eyelid a decade or two later.
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Aside from the dangerous amount of PMMA and the fact that the procedure was done in a makeshift home clinic, the whole thing was also illegal, prosecutors say, since Furtado isn't licensed to practice medicine in Rio.
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The pod's front face is made up of PMMA Smart Glass, which could allow digital content to be presented to passersby — whether this be artwork, public information or commercial content (get that sweet, sweet advertising revenue for more pods).
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According to prosecutors, Furtado injected an unsafe amount of a synthetic resin called polymethylmethacrylate (PMMA) into her butt during the deadly procedure, putting Calixto's life in danger "under the false promise of immediate beauty, selfishly motivated by greed and an easy profit," they wrote.
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Customers are asked to mail their DNA samples to Endeavor's laboratory in Quonset, R.I., where the material is milled, sterilized and enclosed in microscopic capsules of PMMA — you know it as plexiglass — which is often used in medical applications like dentures, bone cement and cosmetic surgery.
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RSPH attributed the rise to an increase in the strength of ecstasy pills, as well the presence of "toxic substances" such as PMMA which can either lace or be mis-labeled entirely as ecstasy, a drug that approximately 12 percent of regular clubbers have been found to ingest in the past year.
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Prosecutors said that the surgeon, Denis Furtado, who is known on social media as Dr. Bumbum, or Dr. Backside, injected the patient, Lilian Calixto, 46, with a far larger dose of PMMA — a synthetic resin that is also known as acrylic glass, and is used in cosmetic surgery to reduce wrinkles — than is considered safe.
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PMMA is routinely produced by emulsion polymerization, solution polymerization, and bulk polymerization. Generally, radical initiation is used (including living polymerization methods), but anionic polymerization of PMMA can also be performed. To produce of PMMA, about of petroleum is needed. PMMA produced by radical polymerization (all commercial PMMA) is atactic and completely amorphous.
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Additionally, since the bases of dental prosthetics are often constructed using PMMA, adherence of PMMA denture teeth to PMMA denture bases is unparalleled, leading to the construction of a strong and durable prosthetic.
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Skeletal structure of methyl methacrylate, the constituent monomer of PMMA Pieces of perspex, the windscreen of a German plane shot down during World War II PMMA is a strong, tough, and lightweight material. It has a density of 1.17–1.20 g/cm3, which is less than half that of glass.Polymethylmethacrylate (PMMA, Acrylic) . Makeitfrom.com. Retrieved 2015-03-23.
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Nevertheless, its environmental stability is superior to most other plastics such as polystyrene and polyethylene, and PMMA is therefore often the material of choice for outdoor applications.Myer Ezrin Plastics Failure Guide: Cause and Prevention , Hanser Verlag, 1996 , p. 168 PMMA has a maximum water absorption ratio of 0.3–0.4% by weight.DATA TABLE FOR: Polymers: Commodity Polymers: PMMA . Matbase.com.
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Non-integrated implants include the acrylic (PMMA), glass, and silicone spheres.
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In 1938 perspex (polymethylmethacrylate, or PMMA) began to replace glass in contact lens manufacture. PMMA lenses were easier to produce so the production of glass lenses soon ended. Lenses made of PMMA are called hard lenses. Soft contact lenses were first produced in 1961 by Czech chemical engineer Otto Wichterle using polyhydroxyethylmethacrylate (pHEMA), a material that achieved long-term commercial application.
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Non-modified PMMA behaves in a brittle manner when under load, especially under an impact force, and is more prone to scratching than conventional inorganic glass, but modified PMMA is sometimes able to achieve high scratch and impact resistance.
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The glass transition temperature (Tg) of atactic PMMA is . The Tg values of commercial grades of PMMA range from ; the range is so wide because of the vast number of commercial compositions which are copolymers with co-monomers other than methyl methacrylate. PMMA is thus an organic glass at room temperature; i.e., it is below its Tg. The forming temperature starts at the glass transition temperature and goes up from there.
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The most common polymers used in bio-MEMS include PMMA, PDMS, OSTEmer and SU-8.
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Another example of polyimides is the polyglutarimide typically made from polymethylmethacrylate (PMMA) and ammonia or a primary amine by aminolysis and cyclization of the PMMA at high temperature and pressure, typically in an extruder. This technique is called reactive extrusion. A commercial polyglutarimide product based on the methylamine derivative of PMMA, called Kamax, was produced by the Rohm and Haas company. The toughness of these materials reflects the rigidity of the imide functional group.
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In the majority of applications, it will not shatter. Rather, it breaks into large dull pieces. Since PMMA is softer and more easily scratched than glass, scratch-resistant coatings are often added to PMMA sheets to protect it (as well as possible other functions).
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However in polymethyl methacrylate (PMMA), a compound similar to PMA, degradation occurs instead. It is soluble in dimethyl sulfoxide (DMSO). PMA is water-sensitive and unlike PMMA, is not stable against alkalies. It is used as macroinitiator to initiate the copolymerisation of HEMA and DMAEMA.
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Indeed, PMMA can also be used to reinforce pedicular fixation in cases of impaired bone quality.
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A rather easy method to prepare protein-polymer hybrid nanoparticles is nanoprecipitation. Spherical nanoparticles composed of BSA-PMMA with diameters of around 100 nm were obtained and the water insoluble chemotherapeutic drug camptothecin was encapsulated within the hydrophobic core consisting of PMMA. Such protein-polymer hybrid nanoparticles possess tunable sizes and surface charges, have attractive bio-compatibilities and allow efficient cell uptake. Camptothecin-encapsulated BSA-PMMA nanoparticles revealed enhanced anti-tumor activity both in vitro and in animals.
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Recently, a class of anthraquinone derivates were shown to have self-healing properties when doped in PMMA matrix.
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Inorganic particulate film/poly(methyl methacrylate) (PMMA)/inorganic particulate film trilayer separators are prepared by dip-coating inorganic particle layers on both sides of PMMA thin films. This inorganic trilayer membrane is believed to be an inexpensive, novel separator for application in lithium-ion batteries from increased dimensional and thermal stability.
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Cell casting is a method used for creating poly(methyl methacrylate) (PMMA) sheets. Liquid monomer is poured between two flat sheets of toughened glass sealed with a rubber gasket and heated for polymerization. Because the glass sheets may contain surface scratches or sag during the process, this traditional method has some disadvantages: among other problems, the PMMA sheets may contain variations in thickness and surface defects. It has since been replaced by the more modern method for making PMMA, extrusion, which gives uniform quality.
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Bone cement chemically is nothing more than Plexiglas (i.e. polymethyl methacrylate or PMMA). PMMA was used clinically for the first time in the 1940s in plastic surgery to close gaps in the skull. Comprehensive clinical tests of the compatibility of bone cements with the body were conducted before their use in surgery.
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There are a few commodity plastics that have emerged as suitable for medical microfluidic applications. These include poly(methyl methacrylate)(PMMA), polystyrene, polycarbonate, and a variety of cyclic polyolefin materials. PMMA has good optical properties for fluorescence, and UV detection modes are relatively easy to seal to themselves. These are available in grades suitable for both injection and compression molding.
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Solid-state dye lasers (SSDL) were introduced in 1967 by Soffer and McFarland. In these solid-state lasers, the gain medium is a laser dye-doped organic matrix such as poly(methyl methacrylate) (PMMA), rather than a liquid solution of the dye. An example is rhodamine 6G-doped PMMA. These lasers are also referred to as solid-state organic lasers and solid-state dye-doped polymer lasers.
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MGD is typically used to define limits on mammography exposures by national and international organisations such as the European Union and International Atomic Energy Agency, at <2.5 milligray (mGy) per exposure to a standard breast (4.5 cm PMMA). In routine quality assurance testing of mammographic equipment, MGD measurements for a range of effective breast thicknesses with PMMA, and from real patient exposures, is widely recommended.
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Industrial Specialties segment produces major chemical intermediates such as thiochemicals (for animal nutrition, gas natural odorant), fluorochemicals (for refrigeration, air conditioning, blowing agent for insulating foam), PMMA (or acrylic glass for furnitures, automotive applications, noise barriers), and hydrogen peroxide (pulp and textile bleaching, chemical synthesis, water treatment). The business segment's flagship brands include Altuglas (PMMA), Albone (hydrogen peroxide), DMDS (agricultural fumigant) and Forane (refrigerants).
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The typical choice, poly(methyl methacrylate) (PMMA) is applied to the substrate by a glue-down process in which a precast, high- molecular-weight sheet of PMMA is attached to the plating base on the substrate. The applied photoresist is then milled down to the precise height by a fly cutter prior to pattern transfer by X-ray exposure. Because the layer must be relatively free from stress, this glue-down process is preferred over alternative methods such as casting. Further, the cutting of the PMMA sheet by the fly cutter requires specific operating conditions and tools to avoid introducing any stress and crazing of the photoresist.
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At this stage, the PMMA structures can be released as the final product (e.g., optical components) or can be used as molds for subsequent metal deposition.
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In the 1990s, new forms of improved PMMA, such as modified PMMA, with high optical quality characteristics were introduced. Gain media research for SSDL has been rather active in the 21st century, and various new dye-doped solid-state organic matrices have been discovered.A. J. C. Kuehne and M. C. Gather, Organic Lasers: Recent Developments on Materials, Device Geometries, and Fabrication Techniques, Chem. Rev. 116, 12823-12864 (2016).
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In the figure 20 shown, the shaded region is the interface excess. The PS phase is located at x<0 whereas the PMMA phase is located at x>0. Please refer to the source to obtain complete analysis of the figure. Thus the authors were able to see that copolymer chains segregate to the interfacial region between the PS and PMMA homolymer phases and elevated temperatures while others remain in bulk.
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Methedrone (para-methoxymethcathinone, 4-methoxymethcathinone, bk-PMMA, PMMC, methoxyphedrine, 4-MeOMC) is a recreational drug of the cathinone chemical class. Chemically, methedrone is closely related to para- methoxymethamphetamine (PMMA), methylone and mephedrone. Methedrone received media attention in 2009 after the death of two young Swedish men. In both cases toxicology analysis showed methedrone was the only drug present in both men during the time of their overdose and subsequent deaths.
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Light microscopic picture of a PMMA-copolymer, made by suspension polymerization SEM-Picture of PMMA-particles, that started to coalesce during suspension polymerization, close to a single bead SEM-picture of a Pac-Man shaped PMMA-copolymer particle, made by suspension polymerization Suspension polymerization is a heterogeneous radical polymerization process that uses mechanical agitation to mix a monomer or mixture of monomers in a liquid phase, such as water, while the monomers polymerize, forming spheres of polymer. This process is used in the production of many commercial resins, including polyvinyl chloride (PVC), a widely used plastic, styrene resins including polystyrene, expanded polystyrene, and high-impact polystyrene, as well as poly(styrene-acrylonitrile) and poly(methyl methacrylate).
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PMA is a soft white rubbery material that is softer than PMMA because its long polymer chains are thinner and smoother and can more easily slide past each other.
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All common molding processes may be used, including injection molding, compression molding, and extrusion. The highest quality PMMA sheets are produced by cell casting, but in this case, the polymerization and molding steps occur concurrently. The strength of the material is higher than molding grades owing to its extremely high molecular mass. Rubber toughening has been used to increase the toughness of PMMA to overcome its brittle behavior in response to applied loads.
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PMMA can be joined using cyanoacrylate cement (commonly known as superglue), with heat (welding), or by using chlorinated solvents such as dichloromethane or trichloromethane"Working with Plexiglas" . science-projects.com. (chloroform) to dissolve the plastic at the joint, which then fuses and sets, forming an almost invisible weld. Scratches may easily be removed by polishing or by heating the surface of the material. Laser cutting may be used to form intricate designs from PMMA sheets.
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As entanglement density increases, the optimum particle size decreases linearly, ranging between 0.1 and 3 micrometers. The effect of particle size on toughening is dependent on the type of test performed. This can be explained because for different test conditions, the failure mechanism changes. For impact strength testing on PMMA where failure occurs by shear-yielding, the optimum size of filler PBA-core PMMA-shell particle was shown in one case to be 250 nm.
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One major industry using hot plate welding is the automotive sector. Tail light housings made of ABS are joined with lenses made of either PMMA or PC using a modified butt joint. ABS and PMMA have similar melting temperatures and can be welded using a single hot plate, while ABS and PC requires dual hot plates due to PC's higher melting temperature. Vacuum suction cups are used to move the parts to prevent scuffing.
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Copolymers, due to their unique tunability of properties, can have a wide range of applications. One example (of many) is nano-scale lithography using block copolymers. One used frequently is a block copolymer made of polystyrene and poly(methyl methacrylate) (abbreviated PS-b- PMMA). This copolymer, upon proper thermal and processing conditions, can form cylinders on the order of a few tens of nanometers in diameter of PMMA, surrounded by a PS matrix.
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116, 12823-12864 (2016). Laser dyes are also used to dope solid-state matrices, such as poly(methyl methacrylate) (PMMA), and ORMOSILs, to provide gain media for solid state dye lasers.
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Silver to Steel: The Modern Designs of Peter Muller-Munk. Prestel Publishing. p. 142 . After the death of its founder in 1967, PMMA continued to take work aligned with its expertise.
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It also has good impact strength, higher than both glass and polystyrene; however, PMMA's impact strength is still significantly lower than polycarbonate and some engineered polymers. PMMA ignites at and burns, forming carbon dioxide, water, carbon monoxide and low-molecular-weight compounds, including formaldehyde. PMMA transmits up to 92% of visible light (3 mm thickness), and gives a reflection of about 4% from each of its surfaces due to its refractive index (1.4905 at 589.3 nm).Refractive index and related constants – Poly(methyl methacrylate) (PMMA, Acrylic glass) . Refractiveindex.info. Retrieved 2014-10-27. It filters ultraviolet (UV) light at wavelengths below about 300 nm (similar to ordinary window glass). Some manufacturersAltuglas International Plexiglas UF-3 UF-4 and UF-5 sheets . Plexiglas.com. Retrieved 2012-05-09.
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The waka taua Te Tuhono in the National Museum of Scotland was restored and partially reconstructed by the Māori craftsman George Nuku, using carved poly(methyl methacrylate) (PMMA) to recreate missing sections.
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In 1986, he designed a musical instrument named "Geophone" for the city of music in Paris. The following year, he created a design of a PMMA Sarod for the musician Amjad Ali Kahn.
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Eye prosthetics, polymethyl methacrylate Polymethyl methacrylate (PMMA), commonly known as acrylic, is a transparent thermoplastic available for use as ocular prosthesis, replacement intraocular lenses when the original lens has been removed in the treatment of cataracts and has historically been used as hard contact lenses. PMMA has a good degree of compatibility with human tissue, much more so than glass. Although various materials have been used to make nonintegrated implants in the past, polymethyl methacrylate is one of the implants of choice.
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The critical dose is the exposure at which unexposed resist begins to be attacked. Due to the insensitivity of PMMA, a typical exposure time for a thick PMMA is six hours. During exposure, secondary radiation effects such as Fresnel diffraction, mask and substrate fluorescence, and the generation of Auger electrons and photoelectrons can lead to overexposure. During exposure the X-ray mask and the mask holder are heated directly by X-ray absorption and cooled by forced convection from nitrogen jets.
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Synthetic casting "resin" for embedding display objects in Plexiglas/Lucite (PMMA) is simply methyl methacrylate liquid, into which a polymerization catalyst is added and mixed, causing it to "set" (polymerize). The polymerization creates a block of PMMA plastic ("acrylic glass") which holds the display object in a transparent block. Another synthetic polymer, sometimes called by the same general category, is acetal resin. By contrast with the other synthetics, however, it has a simple chain structure with the repeat unit of form −[CH2O]−.
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Due to its aforementioned biocompatibility, Poly(methyl methacrylate) is a commonly used material in modern dentistry, particularly in the fabrication of dental prosthetics, artificial teeth, and orthodontic appliances. ; Acrylic prosthetic construction: Pre-polymerized, powdered PMMA spheres are mixed with a Methyl Methacrylate liquid monomer, Benzoyl Peroxide (initiator), and NN-Dimethyl-P-Toluidine (accelerator), and placed under heat and pressure to produce a hardened polymerized PMMA structure. Through the use of injection molding techniques, wax based designs with artificial teeth set in predetermined positions built on gypsum stone models of patients' mouths can be converted into functional prosthetics used to replace missing dentition. PMMA polymer and methyl methacrylate monomer mix is then injected into a flask containing a gypsum mold of the previously designed prosthesis, and placed under heat to initiate polymerization process.
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The curriculum follows the guidelines of the 1995 STCW and the Policies, Standards and Guidelines for Maritime Education 1997 set by the Commission on Higher Education. The PMMA is part of the Luzon Science Consortium.
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In addition to curettage, electric or chemical cauterization (via phenol) can be used as well as cryotherapy and wide or marginal resection. Depending on the size of the subsequent defect, autograft or allograft bone grafts are the preferred filling materials. Other options include substituting polymethylmethacrylate (PMMA) or fat implantation in place of the bone graft. The work of Ramappa et al suggests that packing with PMMA may be a more optimal choice because the heat of polymerization of the cement is thought to kill any remaining lesion.
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The enhanced stiffness and toughness of PMMA fiber meshes by means of inorganic nanotubes addition may have potential uses as impact-absorbing materials, e.g. for ballistic vests.Nano-Armor: Protecting the Soldiers of Tomorrow. Physorg.com (2005-12-10).
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In the United States, E.I. du Pont de Nemours & Company (now DuPont Company) subsequently introduced its own product under the trademark Lucite. In 1936 ICI Acrylics (now Lucite International) began the first commercially viable production of acrylic safety glass. During World War II both Allied and Axis forces used acrylic glass for submarine periscopes and aircraft windshields, canopies, and gun turrets. Airplane pilots whose eyes were damaged by flying shards of PMMA fared much better than those injured by standard glass, demonstrating better compatibility between human tissue and PMMA than glass.
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These cylinders can then be etched away under high exposure to UV light and acetic acid, leaving a porous PS matrix. The unique property of this material is that the size of the pores (or the size of the PMMA cylinders) can be easily tuned by the ratio of PS to PMMA in the synthesis of the copolymer. This can be easily tuned due to the easy control given by living polymerization reactions, thus making this technique highly desired for various nanoscale patterning of different materials for applications to catalysis, electronics, etc.
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Projects included vehicle design, a corporate identity for the new Three Rivers Stadium in Pittsburgh and a series of unique, eye- catching trolleys as a publicity campaign for Pittsburgh's Port Authority Transit (PAT) (now Port Authority of Allegheny County). Despite these successes, PMMA struggled in the years following Muller-Munk's death. By 1973, staff had been reduced to two officers and 20 employees. To adapt to the changing marketplace, PMMA management decided to merge with Wilbur Smith Associates (now CDM Smith) on January 1, 1974, rendering Peter Muller-Munk Associates a division of WSA.
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J. Appl. Phys. 29, 2212 (1990). At a dose of 160 μC/cm2, corresponding to 15 mJ/cm2 EUV dose assuming one electron/photon, 30 eV electrons removed 7 nm of PMMA resist after standard development.A. Thete et al.
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Methyl methacrylate (MMA) is an organic compound with the formula CH2=C(CH3)COOCH3. This colorless liquid, the methyl ester of methacrylic acid (MAA), is a monomer produced on a large scale for the production of poly(methyl methacrylate) (PMMA).
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A system called "Niess Elliptical Survive Rings". The cars have three seats and are fitted with airbags. It has McPherson suspensions and disc brakes all round. The internal and external panels of the bodyshell is made of ABS/PMMA plastic.
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Acrylic nails are made out of acrylic glass (PMMA). When it is mixed with a liquid monomer (usually ethyl methacrylate mixed with some inhibitor) it forms a malleable bead. This mixture begins to cure immediately, continuing until completely solid in minutes.
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The safety of such inks for use on humans is widely debated in the tattoo community. The ingredients in some "glow" inks are listed as: (PMMA) Polymethylmethacrylate 97.5% and microspheres of fluorescent dye 2.5% suspended in UV sterilized, distilled water.
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Basel, Karger, 2013, vol 3, pp 38–55 Polymethylmethacrylate (PMMA) was the first material to be used successfully in intraocular lenses. British ophthalmologist Sir Harold Ridley observed that Royal Air Force pilots who sustained eye injuries during World War II involving PMMA windshield material did not show any rejection or foreign body reaction. Deducing that the transparent material was inert and useful for implantation in the eye, Ridley designed and implanted the first intraocular lens in a human eye. Advances in technology have brought about the use of silicone and acrylic glass, both of which are soft foldable inert materials.
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In addition to being used for their traditional properties, bioactive ceramics have seen specific use for due to their biological activity. Calcium phosphates, oxides, and hydroxides are common examples. Other natural materials — generally of animal origin — such as bioglass and other composites feature a combination of mineral-organic composite materials such as HAP, alumina, or titanium dioxide with the biocompatible polymers (polymethylmethacrylate): PMMA, poly(L-lactic) acid: PLLA, poly(ethylene). Composites can be differentiated as bioresorbable or non-bioresorbable, with the latter being the result of the combination of a bioresorbable calcium phosphate (HAP) with a non-bioresorbable polymer (PMMA, PE).
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Poly(methyl methacrylate) (PMMA) is the material of choice for denture teeth, however ceramic denture teeth have been, and still are used for this purpose. The main benefit associated with the use of ceramic teeth is their superior wear resistance. There are however a number of disadvantages to using ceramic for denture teeth including their inability to form chemical bonds with the PMMA denture base; rather, ceramic teeth are attached to the base via mechanical retention which increases the chance of debonding during use over time. Additionally, they are more likely to fracture due to their brittle nature.
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As part of this work, Priestley studied plexiglas, a composite system of poly(methyl methacrylate) (PMMA) and poly(butyl methacrylate) (PBMA) that is found in coronary stents and paints. He combines experimental studies with computational investigations to better understand the distribution of the PMMA and PBMA throughout the plexiglass. Through his understanding of phase transitions, Priestley has shown that it is possible to precisely control nanostructures, and realised self-assembled biopolymers for use in artificial skin. Alongside his work on polymeric systems, Priestley has investigated nanoparticles, specifically engineered nanoscale zerovalent iron (enZVI) particles, as a means to clean groundwater.
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PMMs can be made with a gradient index (a material whose refractive index varies progressively across the length or area of the material). One such material involved depositing a thermoplastic, known as a PMMA, on a gold surface via electron beam lithography.
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ASA can be welded to itself or to some other plastics. Ultrasonic welding can be used to join ASA to PVC, ABS, SAN, PMMA, and some others. ASA can be solvent-welded, using e.g. cyclohexane, 1,2-dichloroethane, methylene chloride, or 2-butanone.
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PMMA chambers used to measure methane and CO2 emissions in Storflaket peat bog near Abisko, northern Sweden. Sea ice loss is correlated with warming of Northern latitudes. This has melting effects on permafrost, both in the sea, and on land. Lawrence et al.
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PMMA vaporizes to gaseous compounds (including its monomers) upon laser cutting, so a very clean cut is made, and cutting is performed very easily. However, the pulsed lasercutting introduces high internal stresses along the cut edge, which on exposure to solvents produce undesirable "stress-crazing" at the cut edge and several millimetres deep. Even ammonium-based glass-cleaner and almost everything short of soap- and-water produces similar undesirable crazing, sometimes over the entire surface of the cut parts, at great distances from the stressed edge. Annealing the PMMA sheet/parts is therefore an obligatory post-processing step when intending to chemically bond lasercut parts together.
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Being transparent and durable, PMMA is a versatile material and has been used in a wide range of fields and applications such as rear-lights and instrument clusters for vehicles, appliances, and lenses for glasses. PMMA in the form of sheets affords to shatter resistant panels for building windows, skylights, bulletproof security barriers, signs & displays, sanitary ware (bathtubs), LCD screens, furniture and many other applications. It is also used for coating polymers based on MMA provides outstanding stability against environmental conditions with reduced emission of VOC. Methacrylate polymers are used extensively in medical and dental applications where purity and stability are critical to performance.
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Acrylic MICS-IOL in holder The materials that have been used to manufacture intraocular lens implants include polymethylmethacrylate (PMMA), silicone, hydrophobic acrylate, hydrophilic acrylate and collamer.Belluci R. An Introduction to Intraocular Lenses: Material, Optics, Haptics, Design and Aberration. In: Güell JL (ed): Cataract. ESASO Course Series.
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Good results are reported in multiple complicated pediatric glued IOL situations, such as homocystinuria with subluxation, aniridia with cataractous subluxated lens, Weill-Marchesani syndrome with microspherophakia and glaucoma. In dislocated posterior chamber PMMA IOL, the same IOL can be repositioned, thereby reducing the need for further manipulation.
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In 2007, to respond to the current trends of the maritime industry, the Maritime College of Southwestern University was re-established as The Maritime Regiment. In 2008, the college was recognized as a sister school of PMMA (Phil. Merchant Marine Academy) as its program gained recognition.
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The rubber chains form separate phases which are 10-20 micrometers in diameter. When the product is stressed, crazing from the particles helps to increase the strength of the polymer. The method of rubber toughening has been used to strengthen other polymers such as PMMA and nylon.
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Poly(methyl acrylate) (PMA) is a hydrophobic synthetic acrylate polymer. PMA, though softer than polymethyl methacrylate (PMMA), is tough, leathery, and flexible. It has a low glass-transition temperature about 10°C (12.5°C in case of PMA38). High-energy radiation leads to cross linking in PMA.
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Recently, several classes of organic dyes were discovered that self-heal after photo-degradation when doped in PMMA and other polymer matrices. This is also known as reversible photo-degradation. It was shown that, unlike common process like molecular diffusion, the mechanism is caused by dye-polymer interaction.
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Even after 50 MEDs (minimal erythemal doses), 98.4% remains intact. It helps prevent the photodegradation of other sunscreen actives like avobenzone. A recent development is Tinosorb S Aqua, which is bemotrizinol in a PMMA matrix dispersed in water. This makes it possible to add bemotrizinol to the water phase.
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A plastic scintillator based on PMMA in this way boasts transparency to its own radiation, helping to ensure uniform collection of light. Other common bases include polyvinyl xylene (PVX) polymethyl, 2,4-dimethyl, 2,4,5-trimethyl styrenes, polyvinyl diphenyl, polyvinyl naphthalene, polyvinyl tetrahydronaphthalene, and copolymers of these and other bases.
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The sex, age, and race of the patient, and such things as the barometric pressure and ambient humidity will change slightly the required ablation. The formula was derived based on creating a theoretical lenticular surface in a polymethylmethacrylate (PMMA) model, and modified by testing on in vivo animal tissue.
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Pressure is used during the curing process to minimize polymerization shrinkage, ensuring an accurate fit of the prosthesis. Though other methods of polymerizing PMMA for prosthetic fabrication exist, such as chemical and microwave resin activation, the previously described heat-activated resin polymerization technique is the most commonly used due to its cost effectiveness and minimal polymerization shrinkage. ; Artificial teeth: While denture teeth can be made of several different materials, PMMA is a material of choice for the manufacturing of artificial teeth used in dental prosthetics. Mechanical properties of the material allow for heightened control of aesthetics, easy surface adjustments, decreased risk of fracture when in function in the oral cavity, and minimal wear against opposing teeth.
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The stringed-instrument maker, Pierre-Jean Croset, is the son of an engineer father and inventor who worked for Altulor: a company that produced synthetic materials. As a result, during his childhood, Croset discovered the properties of a kind of PMMA named "Altuglas" (diffuser of light, transparent and bright) by diverting the usage of a PMMA blowpipe. After having thought for a long time about John Cage's remark: " to create new music it is necessary to create new tools", he was directed by the researcher and acoustician Émile Leipp, director of the Laboratory of Musical Acoustic ( CNRS) of the University of Jussieu, Paris. He focused on creating a revolutionary instrument that would enable him to create music.
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In 1974, his first glass Harmonic Lyre made with PMMA altuglas cast was designed. He had the opportunity to play this instrument at the tenth Biennial event of Paris in 1977 at the Museum of Modern Art in Paris. This electroacoustic lyre consists of 18 strings and at least two micro-sensors for each of the strings. By 2010, he had successfully designed four harmonic lyres, 3 glass guitars of PMMA and carbon fiber neck, "water drums" for John Cage's creation with the " percussions of Strasbourg" (1989), as well as various other original instruments which include musical wind mills, wind chimes, kalimbé, musical jackstraw in bamboo for children, musical boomerangs, an acoustic game of bowls, and so on.
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In the Philippines, the term cadet is used in mostly military attached organizations, but it is more distinctive in the service academies of the Philippines, [e.g., the Philippine Military Academy (PMA), the Philippine National Police Academy (PNPA), Philippine Merchant Marine Academy (PMMA), Maritime Academy of Asia and the Pacific (MAAP) and Aerospace Cadets of the Philippines (ACP)]. Graduates of these service academies are automatically given officer commissions in the Armed Forces of the Philippines, the Philippine National Police, Philippine Coast Guard, the Bureau of Fire Protection, and Bureau of Jail Management and Penology. Graduates of PMMA are given reserve officer status in the Philippine Navy and mostly go to private shipping firms.
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Temperature rise in PMMA resist is mainly from heat conducted from the substrate backward into the resist and from the mask plate through the inner cavity air forward to the resist, with X-ray absorption being tertiary. Thermal effects include chemistry variations due to resist heating and geometry-dependent mask deformation.
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Second, the PMMA block prevents the dissolution of BSM in aqueous environments. This behavior is imperative in the lubrication of cardiovascular stents and urinary catheters as they are inserted within patients. Due to the adsorption of BSM, the hydrophobicity of the surface decreases as well as the incidence of bacterial adhesion.
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Thus, silicon micromachining allows high geometric precision and long-term stability, since mechanically moving parts, e.g. valve flaps, do not exhibit wear and fatigue. As an alternative to silicon polymer-based materials like PDMS, PMMA, PLLA, etc. can be used due to the superior strength, enhanced structural properties, stability and inexpensiveness.
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Methyl isobutyl ketone is also used as a denaturing agent for denatured alcohol. When mixed with water or isopropyl alcohol MIBK serves as a developer for PMMA electron beam lithography resist. MIBK is used as a solvent for CS in the preparation of the CS spray used currently by British police forces.
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The most common bases used in plastic scintillators are the aromatic plastics, polymers with aromatic rings as pendant groups along the polymer backbone, amongst which polyvinyltoluene (PVT) and polystyrene (PS) are the most prominent. While the base does fluoresce in the presence of ionizing radiation, its low yield and negligible transparency to its own emission make the use of fluors necessary in the construction of a practical scintillator. Aside from the aromatic plastics, the most common base is polymethylmethacrylate (PMMA), which carries two advantages over many other bases: high ultraviolet and visible light transparency and mechanical properties and higher durability with respect to brittleness. The lack of fluorescence associated with PMMA is often compensated through the addition of an aromatic co-solvent, usually naphthalene.
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The addition of WS2 nanotubes to epoxy resin improved adhesion, fracture toughness and strain energy release rate. The wear of the nanotubes-reinforced epoxy is lower than that of pure epoxy. WS2 nanotubes were embedded into a poly(methyl methacrylate) (PMMA) nanofiber matrix via electrospinning. The nanotubes were well dispersed and aligned along fiber axis.
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The Beevers Miniature Models company in Edinburgh (now operating as Miramodus) produced small models beginning in 1961 using PMMA balls and stainless steel rods. In these models, the use of individually drilled balls with precise bond angles and bond lengths enabled large crystal structures to be accurately created in a light and rigid form.
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A synthetic material may be used as a temporary antibiotic spacer before being replaced by a more permanent material. For example, the Masquelet procedure consists of initially using PMMA mixed with an antibiotic (vancomycin or gentamicin) for 4–12 weeks, and then replacing the space with an autologous bone graft. It can be used to treat posttraumatic bone defects.
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After exposure, development, and electroplating, the resist is stripped. One method for removing the remaining PMMA is to flood expose the substrate and use the developing solution to cleanly remove the resist. Alternatively, chemical solvents can be used. Stripping of a thick resist chemically is a lengthy process, taking two to three hours in acetone at room temperature.
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Advantages of using PMMA is its malleability, low cost, high strength and high durability. Its disadvantages include being vulnerable to infection as bacteria may adhere to its fibrous layer, as well as its brittle nature and having no growth potential. Other common synthetic materials for cranioplasty include titanium and hydroxyapatite. Titanium was first used for cranioplasty in 1965.
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This prompted a search for a more suitable material. A German salesman showed a polyethylene gear sample to Charnley's machinist, sparking the idea to use this material for the acetabular component. The UHMWPE acetabular component was introduced in 1962. Charnley's other major contribution was to use polymethylmethacrylate (PMMA) bone cement to attach the two components to the bone.
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A study by the College of Nanoscale Science and Engineering (CNSE) presented at the 2013 EUVL Workshop indicated that, as a measure of electron blur, 50-100 eV electrons easily penetrated beyond 10 nm of resist thickness in PMMA or a commercial resist. Furthermore dielectric breakdown discharge is possible. G. Denbeaux et al., 2013 International Workshop on EUV Lithography.
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Cover lens bonding: To fill the air gap in touch panel sensors that use a cover lens (such as clear plastic PMMA) and the glass touch panel sensor. Direct bonding: To achieve the highest amount of contrast, such as in an outdoor viewing application, it is necessary to “directly bond” the cover lens to the LCD module.
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For thermosetting plastics that require only one monomer, the monomer compound is the "resin". For example, liquid methyl methacrylate is often called the "resin" or "casting resin" while in the liquid state, before it polymerizes and "sets". After setting, the resulting PMMA is often renamed acrylic glass, or "acrylic". (This is the same material called Plexiglas and Lucite).
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The Philippine Merchant Marine Academy or PMMA is located here. San Narciso also houses the Magsaysay Memorial College, which offers bachelors courses and other 2-year courses. Also located in San Narciso is the Zambales Academy, one of the oldest secondary education institution in the province, it is where former president Ramon Magsaysay took his secondary education.
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It has McPherson suspension and disc brakes all round. The internal and external panels of the bodyshell are made in ABS/PMMA plastic. It uses scissor doors and also has a Boblbee backpack space integrated into the design. The 828 has a list price of US$14,000 and the 012 has a list price of US$28,000.
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The material was developed in 1928 in several different laboratories by many chemists, such as William Chalmers, Otto Röhm, and Walter Bauer, and was first brought to market in 1933 by German Röhm & Haas AG (as of January 2019 part of Evonik Industries) and its partner and former U.S. affiliate Rohm and Haas Company under the trademark Plexiglas acrylic.Plexiglas history by Evonik (German only) PMMA is an economical alternative to polycarbonate (PC) when tensile strength, flexural strength, transparency, polishability, and UV tolerance are more important than impact strength, chemical resistance, and heat resistance. Additionally, PMMA does not contain the potentially harmful bisphenol-A subunits found in polycarbonate and is a far better choice for laser cutting. It is often preferred because of its moderate properties, easy handling and processing, and low cost.
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These turbines (or rotors) come in a variety of diameters (outside diameter), from 0.70–15.0 mm, and are usually spun on air or nitrogen gas. The rotors are made from a number of different materials such as ceramics e.g. zirconia, silicon nitride or polymers such as poly(methyl methacrylate) (PMMA), polyoxymethylene (POM). The cylindrical rotors are axially symmetric about the axis of rotation.
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Materials science is closely related to civil engineering. It studies fundamental characteristics of materials, and deals with ceramics such as concrete and mix asphalt concrete, strong metals such as aluminum and steel, and thermosetting polymers including polymethylmethacrylate (PMMA) and carbon fibers. Materials engineering involves protection and prevention (paints and finishes). Alloying combines two types of metals to produce another metal with desired properties.
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Indium gallium phosphide is a solid solution of indium phosphide and gallium phosphide. Ga0.5In0.5P is a solid solution of special importance, which is almost lattice matched to GaAs. This allows, in combination with (AlxGa1−x)0.5In0.5, the growth of lattice matched quantum wells for red emitting semiconductor lasers, e.g. red emitting (650nm) RCLEDs or VCSELs for PMMA plastic optical fibers.
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Doctors discovered the reshaping phenomena of glass lenses as early as the 1940s. This history of orthokeratology includes contributions made by multiple authors to the use of contact lenses for myopia reduction.J Am Optom Assoc. 1982 Mar;53(3):187-95 George Jessen created what was probably the first orthokeratology design in the 1960s made from PMMA material, which he marketed as "Orthofocus".
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The separation chamber consists of a backplate and a front plate. The backplate usually consists of a cooled aluminum block, covered with a plastic covered glass mirror. The front plate is nowadays made of PMMA, in earlier times glass has been used. The distance between the front- and the backplate can be adjusted by spacers and is usually between 0.1 - 0.5 mm.
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The nanoparticles must be smaller than the radius of gyration of the polymer, in the case of PMMA this is about 6 nm. Additionally, as nanoparticles increase in size viscosity increases, slowing the process. For a pure polymer deposition speeds of 200 μm/s are achievable. Adding nanoparticles reduces speeds to 2 μm/s, but is still faster than regular Dip Pen Lithography.
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The cartilages and the anterior cruciate ligament are removed; the posterior cruciate ligament may also be removed but the tibial and fibular collateral ligaments are preserved. Metal components are then impacted onto the bone or fixed using polymethylmethacrylate (PMMA) cement. Alternative techniques exist that affix the implant without cement. These cement-less techniques may involve osseointegration, including porous metal prostheses.
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This leads to non-repetitive and large hysteresis I-V characteristics. Researchers must carry out electrical measurements in vacuum. Graphene surfaces can be protected by a coating with materials such as SiN, PMMA and h-BN. In January 2015, the first stable graphene device operation in air over several weeks was reported, for graphene whose surface was protected by aluminum oxide.
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In "microphase separation" the blocks form nanometer-sized structures. Depending on the relative lengths of each block, several morphologies can be obtained. In diblock copolymers, sufficiently different block lengths lead to nanometer-sized spheres of one block in a matrix of the second (for example PMMA in polystyrene). Using less different block lengths, a "hexagonally packed cylinder" geometry can be obtained.
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This gave him the freedom to follow whatever road of enquiry he wished and he continued his work pushing the limits of what was called at the time microfabrication. Over the next ten years he conducted a series of careful experiments measuring the ultimate resolution of electron beam lithography"Resolution Limits of PMMA Resist for Electron Beam Exposure", 9th Int. Conf.
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Scheme 1. Homolytic cleavage of poly(methyl methacrylate) (PMMA). Polymers have been observed to undergo homolytic bond cleavage through the use of radical reporters such as DPPH (2,2-diphenyl-1-picrylhydrazyl) and PMNB (pentamethylnitrosobenzene.) When a bond is cleaved homolytically, two radical species are formed that can recombine to repair damage or can initiate other homolytic cleavages which can in turn lead to more damage.
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Poly(methyl methacrylate) (PMMA), also known as acrylic or acrylic glass as well as by the trade names Plexiglas, Acrylite, Lucite, and Perspex among several others (see below), is a transparent thermoplastic often used in sheet form as a lightweight or shatter-resistant alternative to glass. The same material can be utilised as a casting resin, in inks and coatings, and has many other uses.
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Experiments in Fluids 50, 1183–1206 (2010).doi:10.1007/s00348-010-0996-8 Due to the moderate dielectric constant of CXB (ε = 7.9 ), PMMA acquires charges that can be screened by the addition of salt (e.g. tetrabutyl ammonium bromide), leading to a very good approximation of colloidal hard sphere.Royall, C. P., Poon, W. C. K. & Weeks, E. R. In search of colloidal hard spheres.
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Scientists have exploited the topology of the random network to fabricate materials of comparable performance for application as ultra-white paints and coatings. For instance, in 2018 Syurik et al. have developed a bioinspired PMMA-based material which scatters light efficiently whilst being flexible and switchable in appearance. Another recent example consists of the use of cellulose nanofibrils to fabricate ultra-white paper for cosmetics and coatings.
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Palazzo Parisio, Malta. In domestic greenhouses, the glass used is typically 3mm (or ⅛″) 'horticultural glass' grade, which is good quality glass that should not contain air bubbles (which can produce scorching on leaves by acting like lenses). Plastics mostly used are polyethylene film and multiwall sheets of polycarbonate material, or PMMA acrylic glass. Commercial glass greenhouses are often high-tech production facilities for vegetables or flowers.
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Studies of the degradation profiles of low-density polyethylene (LDPE), polymethylmethacrylate (PMMA) and polyvinylchloride (PVC) show that photooxidation was higher at the front and back surfaces than in the interior bulk of the material. Because ultraviolet radiation is not strongly absorbed by these materials, a considerable amount of the radiation incident on the front surface is transmitted to the back surface where it initiates photooxidation.
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Otto Röhm was the first chemist who isolated and applied enzymes in technical applications. This led to a revolution in the production and in the use of washing detergents around 1914. In 1920 he introduced enzymes in the pharmaceutical industry and 1934 in the food industry, first application here was the clarifying of fruit juices. Additionally, the development of polymethyl methacrylate (PMMA) contributed to his economical success.
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Stress-whitening is where a white line appears along a bend or curve when a material is stressed by bending or punching operations. The appearance of white line indicates that there is an onset of failure of the corresponding material. This phenomenon is known as "stress-whitening". This is more common in amorphous materials, and also in some brittle polymers like PS, PMMA and Polycarbonate.
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Four analogues of PMA have been reported to be sold on the black market, including PMMA, PMEA,John F. Casale, Patrick A. Hays, Trinette K. Spratley, and Pamela R. Smith. The Characterization of 4-Methoxy-N-ethylamphetamine Hydrochloride. DEA Microgram Journal 2006; 4(1-4) 4-ETA and 4-MTA. These are the N-methyl, N-ethyl, 4-ethoxy and 4-methylthio analogues of PMA, respectively.
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The type I format will be discussed here as it is more commonly used. The type I Kpro is available in single standard pseudophakic power or customized aphakic optic with an 8.5 mm diameter adult size or 7.0 mm diameter pediatric size back plate. The device is currently machined from medical grade polymethylmethacrylate (PMMA) in Woburn, Massachusetts in the United States.Khan B, Dudenhoefer EJ, Dohlman CH. Keratoprosthesis: an update.
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Bromocyclohexane (also called Cyclohexyl bromide, abbreviated CXB) is an organic compound with the chemical formula C6H11Br. It is used to match the refractive index of PMMA for example in confocal microscopy of colloids. A mixture of cis-decalin and CXB can simultaneously match optical index and density of PMMA.Wiederseiner, S., Andreini, N., Epely-Chauvin, G. & Ancey, C. Refractive-index and density matching in concentrated particle suspensions: a review.
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Mean glandular dose (MGD) is a quantity used to describe the absorbed dose of radiation to the breast in mammography. It is based on a measurement of air kerma and conversion factors. MGD can be calculated from measurements made with PMMA blocks. It is often used to compare typical doses to patients between different centres or internationally, and is the preferred measure of the potential risk from mammography.
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They also studied the interface properties of copolymers/Al or Si structures. Figure 19 shows the results obtained which is a typical ERD spectrum of yield vs. energy of P(d-S-b-d-MMA) block copolymer chains that segregated at the interface of the PS and PMMA homopolymers. This profile can then be converted to volume fraction versus depth after doing several mathematical operations to obtain figure 20.
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Poly(ethyl methacrylate) (PEMA) is a hydrophobic synthetic acrylate polymer. It has properties similar to the more common PMMA, however it produces less heat during polymerization, has a lower modulus of elasticity and an overall softer texture. It may be vulcanized using lead oxide as a catalyst and it can be softened using ethanol. It is used as an impression material of ear canals for fabrication of hearing aids.
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Modern dentures are most often fabricated in a commercial dental laboratory or by a denturist using a combination of tissue shaded powders polymethylmethacrylate acrylic (PMMA). These acrylics are available as heat cured or cold cured types. Commercially produced acrylic teeth are widely available in hundreds of shapes and tooth colors. The process of fabricating a denture usually begins with an initial dental impression of the maxillary and mandibular ridges.
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Traditionally, PMMA (acrylic) comprises the core (96% of the cross section in a fiber 1mm in diameter), and fluorinated polymers are the cladding material. Since the late 1990s much higher performance graded-index (GI-POF) fiber based on amorphous fluoropolymer (poly(perfluoro-butenylvinyl ether), CYTOP) has begun to appear in the marketplace. Polymer optical fibers are typically manufactured using extrusion, in contrast to the method of pulling used for glass fibers.
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The reflection makes the white brighter, but dilutes black and other colors, which decreases contrast. LOCA suppliers aim to match the refractive index of glass and clear plastic PMMA (refractive index approximately 1.5) used in displays to minimize loss. LOCA suppliers such as Momentive Materials and Henkel report an increased contrast of 400% in sunlight through the use of LOCA with Anti-Reflective glass, vastly improving the viewing experience.Henkel LOCA [www.loctite.
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Mechanical force can provide a source of energy used by a desired chemical reaction. To create such materials, mechanically sensitive chemical groups called mechanophores are built into the chemical structure of the polymer. In one set of experiments, researchers used spiropyran molecules to detect mechanical stress. The spiropyran (SP) mechanophore was covalently bonded into a stretchy barbell-shaped polymer called polymethyl acrylate (PMA) and a small, glasslike bead-shaped polymer called polymethyl methacrylate (PMMA).
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He found that joint surfaces could be replaced by implants cemented to the bone. His design consisted of a stainless steel one-piece femoral stem and head ,and a polyethylene, acetabular component, both of which were fixed to the bone using PMMA (acrylic) bone cement. For over two decades, the Charnley Low Friction Arthroplasty and its derivative designs were the most- used systems in the world. This formed the basis for all modern hip implants.
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Alternatively, SMA is applied using its transparency in combination with other transparent materials like PMMA or the heat resistancy to heat-boost other polymers materials like ABS or PVC. The solubility of SMA in alkaline solutions makes it suitable for various applications in the field of sizings (paper), binders, dispersants and coatings. The specific reactivity of SMA makes it a suitable agent for compatibilizing normally incompatible polymers (e.g. ABS/PA blends) or cross-linking.
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In 2006, Rotterdam- based 010 publishers published Noten's 328-page monograph titled CH2=C(CH3)C(=O)CH3 enclosures and other TN's (). The title refers to the chemical formula of the PMMA material, much used by Noten. Created out of a pile of thousands of photographs, combined with informational as well as poetic text, the book offers compositions, associations, and narratives to illustrate Noten's work. It achieved the Best Dutch Book Design 2006 award.
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Glass lenses were never comfortable enough to gain widespread popularity. The first lenses to do so were those made from polymethyl methacrylate (PMMA or Perspex/Plexiglas), now commonly referred to as "hard" lenses. Their main disadvantage is they do not allow oxygen to pass through to the cornea, which can cause a number of adverse, and often serious, clinical events. Starting in the late 1970s, improved rigid materials which were oxygen-permeable were developed.
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These included LactoSorb, a fixation system made of completely resorbable material for guided bone regeneration, titanium plates and screws for craniomaxillofacial fixation, instruments for craniomaxillofacial and orthopedic procedures and hard tissue replacements made out of biocompatible polymers, as used in cranial defects. Biomet began using polymethylmethacrylate (PMMA) beads, which are fused together with polyhydroxyethylmethacrylate (PHEMA) for cranial plates, in 1993. The other material is polyetherketoneketone (PEKK), formed either by laser sintering or by 3D printing.
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Besides tetrahedral, trigonal and octahedral holes, there were all-purpose balls with 24 holes. These models allowed rotation about the single rod bonds, which could be both an advantage (showing molecular flexibility) and a disadvantage (models are floppy). The approximate scale was 5 cm per ångström (0.5 m/nm or 500,000,000:1), but was not consistent over all elements. Arnold Beevers in Edinburgh created small models using PMMA balls and stainless steel rods.
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While bacterial infections are common concerns in the medical, dental, and food industries, they are the primary cause of device failures in biological implants. To combat this issue, BSM has been used as a coating for a poly(acrylic acid-b-methyl methacrylate) (PAA-b- PMMA) diblock copolymer. The copolymer provides two mechanisms that contribute to the bacterial resistance of the biomaterial. First, the PAA block assists the adsorption of BSM to the surface.
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For implanting a poly(methyl methacrylate) (PMMA) IOL, the incision has to be enlarged. For implanting a foldable IOL, the incision does not have to be enlarged. The foldable IOL, made of silicone or acrylic of appropriate power is folded either using a holder/folder, or a proprietary insertion device provided along with the IOL. It is then inserted and placed in the posterior chamber in the capsular bag (in-the-bag implantation).
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A choice for new roofs and roof refurbishment. This type of a roof membrane is generally referred to as Liquid Roofing and involves the application of a cold liquid roof coating. No open flames or other heat sources are needed and the glass fiber reinforced systems provide seamless waterproofing around roof protrusions and details. Systems are based on flexible thermoset resin systems such as polyester and polyurethane, and poly-methyl-methacrylate (PMMA).
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Benzoyl peroxide is also used as a radical initiator to induce chain-growth polymerization reactions, such as for polyester and poly(methyl methacrylate) (PMMA) resins and dental cements and restoratives. It is the most important among the various organic peroxides used for this purpose, a relatively safe alternative to the much more hazardous methyl ethyl ketone peroxide. It is also used in rubber curing and as a finishing agent for some acetate yarns.
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Crazes generally propagate perpendicular to the applied tension. Crazing occurs mostly in amorphous, brittle polymers like polystyrene (PS), acrylic (PMMA), and polycarbonate; it is typified by a whitening of the crazed region. The white colour is caused by light-scattering from the crazes. The production of crazing is a reversible process, after applied compressive stress or elevated temperature (higher than glass transformation temperature), it may disappear and the materials will return to optically homogeneous state.
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Crazing can take place in glassy polymers under environmental effects. It is problematic because it requires a much lower stress state and sometimes happens after a long delay, which means it is hard to detect and avoid. For example, PMMA containers in daily use are quite resistive to humidity and temperature without any visible defects. After machine-washing and left in air for one or two days, they will shutter abruptly when wet with gin.
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In 2004 there were about 150 MRI units and about 350 CAT units in use in Canada.Press Release CIHI, "CIHI report shows increase in MRI and CT scanners, up more than 75% in the last decade." Medical Imaging in Canada, 2004 The corneal contact lenses first developed in 1949 gained mass appeal in Canada and elsewhere in the 1960s. Made of polymethyl methacrylate (PMMA) they could be worn up to 16 hours a day.
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Polymers such as some microporous grades of PMMA and various other acrylates (such as polyhydroxylethylmethacrylate aka PHEMA), coated with calcium hydroxide for adhesion, are also used as alloplastic grafts for their inhibition of infection and their mechanical resilience and biocompatibility. Calcifying marine algae such as Corallina officinalis have a fluorohydroxyapatitic composition whose structure is similar to human bone and offers gradual resorption, thus it is treated and standardized as "FHA (Fluoro-hydroxy-apatitic) biomaterial" alloplastic bone grafts.
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The Philippine Merchant Marine Academy (PMMA; ) is a merchant marine academy and one of the military academies of the Philippines, and is operated by the Philippine government. The academy is located in San Narciso, Zambales. Students are called midshipmen but are often also referred to as cadets. Upon graduation students are commissioned as ensigns (second lieutenants) in the Philippine Navy Reserve and have the option to join the merchant marine, the Philippine Navy, or the Philippine Coast Guard.
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Entrance to PMMA in San Narciso, Zambales The academy offers courses for Bachelor of Science degrees in marine transportation and marine engineering. Both are four-year residency courses consisting of three-years of academic studies (first, second, and fourth years). The one year apprentice training (third year) is aboard commercial vessels plying the international sea lanes as deck or engine room cadets. The academy also offers masters degree courses in shipping business management and maritime education.
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Rigid gas permeable lenses are very durable and may last for several years without the need for replacement. PMMA hards were very durable and were commonly worn for 5 to 10 years, but had several drawbacks. Lenses with different replacement schedules can be made of the same material. Although the materials are alike, differences in the manufacturing processes determine if the resulting lens will be a "daily disposable" or one recommended for two or four week replacement.
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The cemented-in prosthesis can be fully loaded very soon after the operation because the PMMA gets most of its strength within 24 hours. The necessary rehabilitation is comparatively simple for patients who have had a cemented-in prosthesis implanted. The joints can be loaded again very soon after the operation, but the use of crutches is still required for a reasonable period for safety reasons. Bone cement has proven particularly useful because specific active substances, e.g.
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Corneal sensitivity is significantly diminished after extended contact lens wear (five or more years). However, this difference in sensitivity is not correlated with a change in the number of nerve fiber bundles in the subbasal plexus of the cornea. Long-term use of PMMA or thick hydrogel contact lenses have been found to cause increased eye irritability, photophobia, blurred vision, and persistent haloes. Long-term use of rigid gas permeable contact lenses has been associated with slower myopic progression.
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A 3D "Electrical Tree" (or Lichtenberg figure), imbedded within a 1.5-inch cube of polymethyl methacrylate (PMMA) In electrical engineering, treeing is an electrical pre-breakdown phenomenon in solid insulation. It is a damaging process due to partial discharges and progresses through the stressed dielectric insulation, in a path resembling the branches of a tree. Treeing of solid high-voltage cable insulation is a common breakdown mechanism and source of electrical faults in underground power cables.
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For example, methyl methacrylate (MMA) can be polymerized to produce Poly(methyl methacrylate) (PMMA - Plexiglas or Perspex) via a repeating series of radical addition steps: :Radical intermediates in the formation of polymethacrylate (plexiglas or perspex). Newer radical polymerization methods are known as living radical polymerization. Variants include reversible addition-fragmentation chain transfer (RAFT) and atom transfer radical polymerization (ATRP). Being a prevalent radical, O2 reacts with many organic compounds to generate radicals together with the hydroperoxide radical.
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Many structures can be formed using the most common, rapid prototyping technology, soft lithography with polydimethylsiloxane(PDMS). PDMS is an inexpensive, clear elastomeric polymer with rubbery mechanical properties at room temperature. In the laboratory, PDMS is mixed in small batches, poured onto moulds, for example, poly(methyl methacrylate)(PMMA), with microscale features, and cured at moderate temperatures for minutes to hours. Open PDMS channels are closed by adhering the channel bearing component to a glass slide or a second, flat piece of PDMS.
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Depending on the size of the nanoparticles, resolutions of 78-400 nm were attained. An O2 plasma etch can be used to remove the PMMA matrix, and in the case of Iron Oxide nanoparticles, further reduce the resolution of lines to 10 nm. Advantages unique to tDPL are that it is a maskless additive process that can achieve very narrow resolutions, it can also easily write many types of nanoparticles without requiring special solution preparation techniques. However there are limitations to this method.
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Recent improvements in the in situ polymerization process have led to the production of polymer-carbon nanotube composites with enhanced mechanical properties. With regards to their energy-related applications, carbon nanotubes have been used to make electrodes, with one specific example being the CNT/PMMA composite electrode. In situ polymerization has been studied to streamline the construction process of such electrodes. Huang, Vanhaecke, and Chen found that in situ polymerization can potentially produce composites of conductive CNTs on a grand scale.
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PMMA chambers used to measure methane and CO2 emissions in Storflaket peat bog near Abisko. Though many research projects are carried out at the station regarding geography and biology in general, particular emphasis is placed on meteorology and plant ecology. Many of these projects overlap as the station hosts research into climate change in the region and the resulting changes to plant communities. In recent years, research has included work on permafrost degradation, the importance of winter climate change and tree-line dynamics.
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The words cadet and officer candidate are synonymous in referring the rank below second lieutenant. In the Philippines, officer candidates are referred to RESCOM, AFPOCS and PCGOBETC students who had baccalaureate degree, foreign service academies and reserve officer pools undergoing 4 months to 1 year of rigorous military training. On the other hand, cadets are referred to students of military schools such as PMA, PNPA, PMMA, MAAP and ACP undergoing 4 years of military training while completing their college degree.
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The principal application, consuming approximately 75% of the MMA, is the manufacture of polymethyl methacrylate acrylic plastics (PMMA). Methyl methacrylate is also used for the production of the co-polymer methyl methacrylate-butadiene-styrene (MBS), used as a modifier for PVC. Another application is as cement used in total hip replacements as well as total knee replacements. Used as the "grout" by orthopedic surgeons to make the bone inserts fix into bone, it greatly reduces post-operative pain from the insertions but has a finite lifespan.
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The nanotubes were well dispersed and aligned along fiber axis. The enhanced stiffness and toughness of PMMA fiber meshes by means of inorganic nanotubes addition may have potential applications as impact-absorbing materials. Optical properties of semiconductor quantum dot-inorganic nanotube hybrids reveal efficient resonant energy transfer from the quantum dot to the inorganic nanotubes upon photoexcitation. Nanodevices based on one-dimensional nanomaterials are thought for next-generation electronic and photoelectronic systems having small size, faster transport speed, higher efficiency and less energy consumption.
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But the center shifted again, this time to Germany because of their superior glass blowing techniques. Shortly following the introduction of the art of glass eye-making to the United States, German goods became unavailable because of World War II. As a result, the US instead made artificial eyes from acrylic plastic. Production of modern ocular prosthetics has expanded from simply using glass into many different types of materials. In the United States, most custom ocular prostheses are fabricated using PMMA (polymethyl methacrylate), or acrylic.
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SCF in V-groove (left) V-groove open microfluidic channel (right) Rectangular open-surface U-grooves are the easiest type of open microfluidic channel to fabricate. This design can maintain the same order of magnitude velocity in comparison to V-groove. Channels are made of glass or high clarity glass substitutes such as polymethyl methacrylate (PMMA), polycarbonate (PC), or cyclic olefin copolymer (COP). To eliminate the remaining resistance after etching, channels are given hydrophilic treatment using oxygen plasma or deep reactive-ion etching(DRIE).
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BVS was first developed by C. P. Chen and R. S. Lakes in 1989 in order to address the shortcomings of existing laboratory techniques for studying viscoelastic materials. It was later refined by M. Brodt et al. to improve the rigidity and resolution of the apparatus, which were sources of error in the original design. First used to study poly(methyl methacrylate) (PMMA), it has since seen applications in determining the properties of bone, capacitor dielectrics, high damping metals, and other such viscoelastic materials.
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A material that is expected to fail by crazing is more likely to benefit from larger particles than a shear prone material, which would benefit from a smaller particle. In materials where crazing and yielding are comparable, a bimodal distribution of particle size may be useful for toughening. At fixed rubber concentrations, one can find that an optimal particle size is a function of the entanglement density of the polymer matrix. The neat polymer entanglement densities of PS, SAN, and PMMA are 0.056, 0.093, and 0.127 respectively.
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Regarding the creation of indentations, or pits, non- crosslinked polymers retain a low glass temperature, around 120 °C for PMMA and if the probe tip is heated to above the glass temperature, it leaves a small indentation. Indentations are made at 3 nm lateral resolution. By heating the probe immediately next to an indentation, the polymer will re-melt and fill in the indentation, erasing it (see also: thermo-mechanical scanning probe lithography). After writing, the probe tip can be used to read the indentations.
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A possible sequence of repeat units A and B in a triblock copolymer might be ~A-A-A-A-A-A-A-B-B-B-B-B-B-B-A-A-A-A-A~.Cowie, p.4 Block copolymers are made up of blocks of different polymerized monomers. For example, polystyrene-b- poly(methyl methacrylate) or PS-b-PMMA (where b = block) is usually made by first polymerizing styrene, and then subsequently polymerizing methyl methacrylate (MMA) from the reactive end of the polystyrene chains.
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SEM-Picture of PMMA-particles fabricated by dispersion polymerization after drying / removal of the organic liquid phase (cyclohexane) At the onset of polymerization, polymers remain in solution until they reach a critical molecular weight (MW), at which point they precipitate. These initial polymer particles are unstable and coagulate with other particles until stabilized particles form. After this point in the polymerization, growth only occurs by addition of monomer to the stabilized particles. As the polymer particles grow, stabilizer (or dispersant) molecules attach covalently to the surface.
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PMMA and PMEA are anecdotally weaker, more "ecstasy-like" and somewhat less dangerous than PMA itself, but can still produce nausea and hyperthermia similar to that produced by PMA, albeit at slightly higher doses. 4-EtOA was briefly sold in Canada in the 1970s, but little is known about it.Alexander & Ann Shulgin, PiHKAL #97 4-MTA, however, is even more dangerous than PMA and produces strong serotonergic effects and intense hyperthermia, but with little to no euphoria, and was implicated in several deaths in the late 1990s.
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The mechanical strength of cellulose fibers can be increased by an order of magnitude by adding only 0.1 wt% of TMCH nanotubes, and measurements of electrical conductivity of polycaprolactone doped with TMCH nanotubes revealed a percolative behavior with an extremely low percolation threshold. The addition of WS2 nanotubes to epoxy resin improved adhesion, fracture toughness and strain energy release rate. The wear of the nanotubes-reinforced epoxy was eight times lower than that of pure epoxy. WS2 nanotubes were also embedded into a poly(methyl methacrylate) (PMMA) nanofiber matrix via electrospinning.
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Rib grafts (whether or not accompanied with the latissimus dorsi muscle) are suitable for larger defects and can bear pressure, but do not cover the whole defect. Implants can be used as well, but are not preferred in patients who are to be irradiated or recently have had an infection or necrosis, because of the increased risk of infection and extrusion. These implants can be factory-made out of metal (titanium), synthetic materials (PMMA, PEEK) or synthetic body-own material (Hydroxylapatite). In the pictures, a reconstruction using a titanium plate is shown.
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Illustrative and secure bromine chemical sample used for teaching. The glass sample vial of the corrosive and poisonous liquid has been cast into an acrylic plastic cube Methyl methacrylate "synthetic resin" for casting (simply the bulk liquid chemical) may be used in conjunction with a polymerization catalyst such as methyl ethyl ketone peroxide (MEKP), to produce hardened transparent PMMA in any shape, from a mold. Objects like insects or coins, or even dangerous chemicals in breakable quartz ampules, may be embedded in such "cast" blocks, for display and safe handling.
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Microstructured Uniformity Tape greatly reduces dark zones by inducing lateral light-spreading in the plane of the light guide. The effect of the 3M Uniformity Tape on the injection of LED light from a nominally lambertian LED is shown in Figure 2a-c. The left image in Figure 2a shows the injection cone angle of the LED into a light guide under normal TIR conditions (+/-42 degrees in a conventional PMMA light guide with an optically flat entrance face). The right image shows a close-up view of the left image.
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Application of Uniformity Tape also appears to provide ancillary benefits. When applied to the input edge of the light guide, the optically clear adhesive will wet out and conform to the surface roughness of the light guide edge so that the film and light guide were optically coupled (i.e., no air is trapped between them). As a result of this optical coupling, the PMMA plate does not require the level of polishing required in a conventional light guide; this suggests that Uniformity Tape could lead to a reduction in manufacturing steps and lower costs.
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Thermoplastic Edgebanding is produced with an extruder, a machine that consists of a loading system for raw materials, a screw inside a barrel that melts and transports the raw materials (plastics PVC, ABS, PP, PMMA and color pigments) through a die which shapes the edgebanding into the required size. After the Edgebanding is extruded, it can be texturized, printed, and lacquered to provide the required finish. The Edgebanding is then rolled and send to customers. Leading thermoplastic Edgebanding manufacturers worldwide are Doellken and Rehau with local manufacturers present.
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For high-aspect-ratio structures the resist-developer system is required to have a ratio of dissolution rates in the exposed and unexposed areas of 1000:1. The standard, empirically optimized developer is a mixture of tetrahydro-1,4-oxazine (), 2-aminoethanol-1 (), 2-(2-butoxyethoxy)ethanol (), and water (). This developer provides the required ratio of dissolution rates and reduces stress-related cracking from swelling in comparison to conventional PMMA developers. After development, the substrate is rinsed with deionized water and dried either in a vacuum or by spinning.
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One major disadvantage of PMMA lenses is that they allow no oxygen to get through to the conjunctiva and cornea, causing a number of adverse and potentially serious clinical effects. By the end of the 1970s and through the 1980s and 1990s, a range of oxygen-permeable but rigid materials were developed to overcome this problem. Chemist Norman Gaylord played a prominent role in the development of these new oxygen-permeable contact lenses. Collectively, these polymers are referred to as rigid gas permeable or RGP materials or lenses.
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This type of LDL is usually incorporated in macrophages, resulting in foam cell formation and formation of an atherosclerotic plaque which narrows or blocks the arteries. Contrary to most anti-atherosclerotic drugs, the anionic polymer only targets the bad cholesterol LDL particles and not the good cholesterol HDL. The delivery of these polymeric particles is now undergoing investigation with Professor Prabhas Moghe. Thirdly, her group is interested in micro-sized striped patterns of protein (such as serum albumin, immunoglobulin G, laminin and other growth factors) on biocompatible polymeric substrates (such as poly(methylmethacrylate) or PMMA).
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A heated probe tip version of Dip Pen Lithography has also been demonstrated, thermal Dip Pen Lithography (tDPL), to deposit nanoparticles.Woo, Dai, King & Sheehan "Maskless Nanoscale Writing of Nanoparticle-Polymer Composites and Nanoparticle Assemblies using Thermal Nanoprobes" NanoLetters (2009) Semiconductor, magnetic, metallic, or optically active nanoparticles can be written to a substrate via this method. The particles are suspended in a PMMA or equivalent polymer matrix, and heated by the probe tip until they begin to flow. The probe tip acts as a nano-pen, and can pattern nanoparticles into a programmed structure.
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Janus particles' two or more distinct faces give them special properties in solution. In particular, they have been observed to self- assemble in a specific way in aqueous or organic solutions. In the case of spherical Janus micelles having hemispheres of polystyrene (PS) and poly(methyl methacrylate) (PMMA), aggregation into clusters has been observed in various organic solvents, such as tetrahydrofuran. Similarly, Janus discs composed of sides of PS and poly(tert-butyl methacrylate) (PtBMA) can undergo back-to-back stacking into superstructures when in an organic solution.
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The common plastic poly (methyl methacrylate) (PMMA) absorbs IR light in the 2.8–25 μm wavelength band, so CO2 lasers have been used in recent years for fabricating microfluidic devices from it, with channel widths of a few hundred micrometers. Because the atmosphere is quite transparent to infrared light, CO2 lasers are also used for military rangefinding using LIDAR techniques. CO2 lasers are used in spectroscopyC. P. Bewick, A. B. Duval, and B. J. Orr, Rotationally selective mode-to-mode vibrational energy transfer in D2CO/D2CO and D2CO/Ar collisions, J. Chem Phys.
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It is now recognized that for insulating materials like PMMA, low energy electrons can travel quite a far distance (several nm is possible). This is due to the fact that below the ionization potential the only energy loss mechanism is mainly through phonons and polarons. Although the latter is basically an ionic lattice effect, polaron hopping can extend as far as 20 nm. The travel distance of secondary electrons is not a fundamentally derived physical value, but a statistical parameter often determined from many experiments or Monte Carlo simulations down to < 1 eV.
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Electron beam lithography (EBL) or electron-beam direct-write lithography (EBDW) scans a focused beam of electrons on a surface covered with an electron-sensitive film or resist (e.g. PMMA or HSQ) to draw custom shapes. By changing the solubility of the resist and subsequent selective removal of material by immersion in a solvent, sub-10 nm resolutions have been achieved. This form of direct-write, maskless lithography has high resolution and low throughput, limiting single-column e-beams to photomask fabrication, low- volume production of semiconductor devices, and research&development.
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PMMA drinking beaker Environmental Stress Cracking (ESC) is one of the most common causes of unexpected brittle failure of thermoplastic (especially amorphous) polymers known at present. According to ASTM D883, stress cracking is defined as "an external or internal crack in a plastic caused by tensile stresses less than its short-term mechanical strength". This type of cracking typically involves brittle cracking, with little or no ductile drawing of the material from its adjacent failure surfaces. Environmental stress cracking may account for around 15-30% of all plastic component failures in service.
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Pyrolysis is one of various types of chemical degradation processes that occur at higher temperatures (above the boiling point of water or other solvents). It differs from other processes like combustion and hydrolysis in that it usually does not involve the addition of other reagents such as oxygen (O2, in combustion) or water (in hydrolysis).Cory A. Kramer, Reza Loloee, Indrek S. Wichman and Ruby N. Ghosh, 2009, Time Resolved Measurements of Pyrolysis Products From Thermoplastic Poly-Methyl-Methacrylate (PMMA) ASME 2009 International Mechanical Engineering Congress and Exposition Pyrolysis produces solids (char), condensable liquids (tar), and uncondensing/permanent gasses.
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232x232pxIncreasing the rubber concentration in a nanocomposite decreases the modulus and tensile strength. In one study, looking at PA6-EPDM blend, increasing the concentration of rubber up to 30 percent showed a negative linear relationship with the brittle-tough transition temperature, after which the toughness decreased. This suggests that the toughening effect of adding rubber particles is limited to a critical concentration. This is examined further in a study on PMMA from 1998; using SAXS to analyze crazing density, it was found that crazing density increases and yield stress decreases until the critical point when the relationship flips.
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The excellent tissue compatibility of PMMA allowed bone cements to be used for anchorage of head prostheses in the 1950s. Today several million procedures of this type are conducted every year all over the world and more than half of them routinely use bone cements - and the proportion is increasing. Bone cement is considered a reliable anchorage material with its ease of use in clinical practice and particularly because of its proven long survival rate with cemented-in prostheses. Hip and knee registers for artificial joint replacements such as those in Sweden and Norway clearly demonstrate the advantages of cemented-in anchorage.
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Any three-dimensional scene can be volumetrically printed, although biological specimens and volumetrically X-rayed objects (i.e., CT scans) are thought to be particularly well suited to this type of imaging. There are several methods for producing a volumetric print, the most common being an index-matched stack of hundreds of sheets of thin clear material (most often PMMA, also known as Lucite or acrylic). Each sheet in the volumetric stack is printed with a color slice of a digital 3D model, placed in a vacuum chamber, and then injected with a fluid matching the index of refraction of the sheet material.
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The line edge roughness in block copolymer patterns is strongly dependent on the interface tension between the two phases, which in turn, depends on the Flory "chi" (χ) parameter.NIST 2011 report on LER in PS-b-PMMA DSA A higher value of χ is preferred for reduced roughness; the interfacial width between domains is equal to 2a(6χ)−1/2, where a is the statistical polymer chain length.A. N. Semenov, Macromolecules 26, 6617 (1993). Moreover, χN > 10.5 is required for sufficient phase segregation, where N is the degree of polymerization (number of monomer repeats in the chain).
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Tribromoethanol can be used as a functional polymerization initator for the introduction of α-hydroxyl groups in poly(methyl methacrylate) (PMMA) and poly(n-butyl acrylate) (PBAK).G. Moineau, M. Minet, Ph. Dubois, Ph. Teyssié, T. Senninger, and R. Jérôme (1999): "Controlled radical polymerization of (meth)acrylates by ATRP with NiBr2(PPh3)2 as catalyst". Macromolecules, volume 32, issue 1, pages 27–35. Mohammed Dirany, Marylène Vayer, Christophe Sinturel, René Erre, Patrick Lacroix-Desmazes, and Bernard Boutevin (2009): "Synthesis and characterization of polystyrene-block-polylactide by combination of ATRP and ROP using tribromoethanol as initiator: Precursors to ordered nanoporous materials".
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To extend the coverage of antibiotics against more bacteria in Type III Gustilo fractures, combination of first generation cephalosporin and aminoglycoside (gentamicin or tobramycin) or a third generation cephalosporin is recommended to cover against nosocomial gram negative bacilli such as Pseudomonas aeruginosa. Adding penicillin to cover for gas gangrene caused by anaerobic bacteria Clostridium perfringens is a controversial practice. Studies has shown that such practice may not be necessary as the standard antibiotic regimen is enough to cover for Clostridial infections. Antibiotic impregnated devices such as tobramycin impregnated Poly(methyl methacrylate) (PMMA) beads and antibiotic bone cement are helpful in reducing rates of infection.
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The second type of IOL, more commonly known as a phakic intraocular lens (PIOL), is a lens which is placed over the existing natural lens and is used in refractive surgery to change the eye's optical power as a treatment for myopia (nearsightedness). IOLs usually consist of a small plastic lens with plastic side struts, called haptics, to hold the lens in place in the capsular bag inside the eye. IOLs were conventionally made of an inflexible material (PMMA), although this has largely been superseded by the use of flexible materials, such as silicone and acrylic glass. Most IOLs fitted today are fixed monofocal lenses matched to distance vision.
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In the electroplating step, nickel, copper, or gold is plated upward from the metalized substrate into the voids left by the removed photoresist. Taking place in an electrolytic cell, the current density, temperature, and solution are carefully controlled to ensure proper plating. In the case of nickel deposition from NiCl2 in a KCl solution, Ni is deposited on the cathode (metalized substrate) and Cl2 evolves at the anode. Difficulties associated with plating into PMMA molds include voids, where hydrogen bubbles nucleate on contaminates; chemical incompatibility, where the plating solution attacks the photoresist; and mechanical incompatibility, where film stress causes the plated layer to lose adhesion.
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The group then encapsulated the vertically aligned nanotubes in PMMA polymer before exposing the top 25\mum of the tubes by etching away some of the polymer. The nanotubes tended to form entangled bundles about 50 nm in diameter because of the solvent drying process used after etching. (As is shown in the figure on the right). The results were tested with a scanning probe microscope, and it showed that the minimum force per unit area as 1.6±0.5×10−2nN/nm2, which is far larger than the figure the team estimated for the typical adhesive force of a gecko's setae, which was 10−4nN/nm2.
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Acrylic resin, in particular the methyl methacrylate type of synthetic resin, produces acrylic glass (also called PMMA, Lucite, Plexiglass), which is not a glass but a plastic polymer that is transparent, and very hard. It is suitable for embedding objects (such as, for example, acrylic trophies), for display purposes. Styrene is a similar liquid monomer at room temperature, which will also polymerize into clear glass-like polystyrene plastic, with addition of a suitable catalyst. A flexible mold can be made of latex rubber, room temperature vulcanized silicone rubber or other similar materials at relatively low cost, but can only be used for a limited number of castings.
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Windscreens of all kinds of vehicles as well as crash-proof glazing or pavement light used in the construction sector are part of the main fields of application. The composite film used mostly in the construction and automotive sectors is composed of polyvinyl butyral (PVB). Other customary intermediate layer materials include ethylene-vinyl acetate (EVA), polyarcylate (PA), poly(methyl methacrylate) (PMMA), polyurethane (PUR), etc. Depending on the number, type and thickness of the glass panes used and intermediate layers, composite glasses are used as safety glass, sound-proof glas, fireproof glass, as well as throw-through-resistant, breakthrough- resistant or ballistic-resistant glass etc.
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Glued IOL can also be performed with various other corneal transplantation / keratoplasty procedures like Descemet's memnbrane endothelial keratoplasty (DMEK), Descemet's stripping endothelial keratoplasty (DSEK) and Penetrating keratoplasty (PK). This glued IOL technique would be useful in many clinical situations in which scleral-fixated IOLs are indicated, such as luxated IOL, dislocated IOL, zonulopathy or secondary IOL implantation. In a case with a dislocated posterior chamber PMMA IOL, the same IOL can be repositioned, thereby reducing the need for further manipulation. Externalization of the greater part of the haptics along the curvature stabilizes the axial positioning of the IOL and thereby prevents any IOL tilt.
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These devices have been developed to realize low-cost, large-area electronic products and biodegradable electronics. OFETs have been fabricated with various device geometries. The most commonly used device geometry is bottom gate with top drain and source electrodes, because this geometry is similar to the thin-film silicon transistor (TFT) using thermally grown SiO2 as gate dielectric. Organic polymers, such as poly(methyl-methacrylate) (PMMA), can also be used as dielectric.. One of the benefits of OFETs, especially compared with inorganic TFTs, is their unprecedented physical flexibility, which leads to biocompatible applications, for instance in the future health care industry of personalized biomedicines and bioelectronics.
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In the 1980s, the use of cadaver allograft disc for filling in small holes received a satisfactory result, and there was a resurgence of the use of cadaver bone. However, cadaver bones and allografts, in general, are not the preferred materials in modern operations. The use of methyl methacrylate (PMMA) for cranioplasty was being developed since World War II, and the material is used extensively since 1954, when there is a high demand for cranioplasty due to a large number of injuries. It becomes malleable when an exothermic reaction occurs between its powder form and benzoyl peroxide, allowing it to be moulded to the cranial defect.
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Corneal surface irregularity and asymmetry are also caused by long-term contact lens wear; these problems are sometimes correlated with astigmatism in contact lens wearers and are thought to be caused by hypoxia, surface molding, and chronic and mild trauma to the cornea from contact lens use. Long-term use of PMMA or thick hydrogel contact lenses have been found to cause corneal warpage (shape distortion). There is some evidence to show that rigid gas permeable contact lenses are capable of slowing myopic progression after long-term wear. This same effect was not found in patients who had worn soft contact lenses for an extended period of time.
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It is one of a number of examples of her work that followed her father's dualism: the pursuit of both fine art and crafts (or design). The base of another more craft-oriented lamp is a sculptural form of a winding snake-like brass tube and bent PMMA with imbedded metal minutiae. She also participated in the Venice Biennale of 1959 and designed the gate, built at the Bezalel Academy, of the President's House, Jerusalem. Schatz lived in Israel, New York, and Northern California where she was part of the Big Sur artists'/writers' colony that included San Francisco sculptor Benny Bufano, author Henry Miller, and her brother Bezalel Schatz.
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Polymers such as PMMA and HEMA:MMA are used as matrices in the gain medium of solid-state dye lasers, also known as solid-state dye-doped polymer lasers. These polymers have a high surface quality and are also highly transparent so that the laser properties are dominated by the laser dye used to dope the polymer matrix. These type of lasers, that also belong to the class of organic lasers, are known to yield very narrow linewidths which is useful for spectroscopy and analytical applications. An important optical parameter in the polymer used in laser applications is the change in refractive index with temperature also known as dn/dT.
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Then, the lignin is separated from the cellulose and hemicellulose structure turning the wood white and allowing the resin penetration to start. Finally, the sample is immersed in a matching resin, usually Poly Methyl Methacrylate (PMMA), under high temperatures (85 °C) and a vacuum for 12 hours. This process fills the space previously occupied by the lignin and the open wood cellular structure resulting in the final transparent wood composite. While the delignification process is a successful method of production, it is limited to its laboratory and experimental production of a small, and low thickness material that is unable to meet its practical application requirements.
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One or two years of hard contact lens wear has not been shown to affect corneal sensitivity, but real changes are observed following five years of hard contact lens wear. However, this significant decrease in corneal sensitivity appears to be reversible. Following cessation of hard contact lens usage, corneal sensitivity has been shown to be fully regained after several months: patients who had worn hard contact lenses for a decade or longer were able to regain normal corneal sensitivity after four months of not wearing contact lenses at all. Long-term use of PMMA or thick hydrogel contact lenses has been found to cause corneal warpage (shape distortion), increased eye irritability, photophobia, blurred vision, and persistent haloes.
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Calculations have also indicated that p-beam writing exhibits minimal proximity effects (unwanted exposure due to secondary electrons), since the secondary electrons induced in proton/electron collisions have low energy. A further advantage stems from the ability of protons to displace atoms while traversing material, thereby increasing localized damage especially at the end of range. P-beam writing produces resistive patterns at depth in silicon, allowing patterning of selective regions with different optical properties as well as the removal of undamaged regions via electrochemical etching. The primary mechanisms for producing structures in resist materials is, in general, bond scissioning in positive resists such as PMMA (polymethylmethacrylate), or cross-linking in negative resists such as SU-8.
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Lithium polymer cells have evolved from lithium-ion and lithium-metal batteries. The primary difference is that instead of using a liquid lithium-salt electrolyte (such as LiPF6) held in an organic solvent (such as EC/DMC/DEC), the battery uses a solid polymer electrolyte (SPE) such as poly(ethylene oxide) (PEO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA) or poly(vinylidene fluoride) (PVdF). The solid electrolyte can typically be classified as one of three types: dry SPE, gelled SPE and porous SPE. The dry SPE was the first used in prototype batteries, around 1978 by Michel Armand, and 1985 by ANVAR and Elf Aquitaine of France, and Hydro Quebec of Canada.
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POF has been called the "consumer" optical fiber because the fiber and associated optical links, connectors, and installation are all inexpensive. Due to the attenuation and distortion characteristics of PMMA fibers, they are commonly used for low-speed, short-distance (up to 100 meters) applications in digital home appliances, home networks, industrial networks (PROFIBUS, PROFINET, Sercos, EtherCAT), and car networks (MOST). The perfluorinated polymer fibers are commonly used for much higher-speed applications such as data center wiring and building LAN wiring. In relation to the future requirements of high-speed home networking, there has been an increasing interest in POF as a possible option for next-generation Gigabit/s links inside the home.
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For self-assembly to take place without intervention of external forces, the process must lead to a lower Gibbs free energy, thus self-assembled structures are thermodynamically more stable than the single, unassembled components. A direct consequence is the general tendency of self- assembled structures to be relatively free of defects. An example is the formation of two-dimensional superlattices composed of an orderly arrangement of micrometre-sized polymethylmethacrylate (PMMA) spheres, starting from a solution containing the microspheres, in which the solvent is allowed to evaporate slowly in suitable conditions. In this case, the driving force is capillary interaction, which originates from the deformation of the surface of a liquid caused by the presence of floating or submerged particles.
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"New Contact Lens Fits Pupil Only", The New York Times, 11 February 1952, p. 27. These were much smaller than the original scleral lenses, as they sat only on the cornea rather than across all of the visible ocular surface, and could be worn up to 16 hours a day. PMMA corneal lenses became the first contact lenses to have mass appeal through the 1960s, as lens designs became more sophisticated with improving manufacturing technology. On October 18, 1964, in a television studio in Washington, D.C., Lyndon Baines Johnson became the first President in the history of the United States to appear in public wearing contact lenses, under the supervision of Dr. Alan Isen, who developed the first commercially viable soft-contact lenses in the United States.
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Low energy electron blur alters the image by reducing the local dose gradient. Low energy electron migration. Low energy electron travel distance (r) can reach at least several nanometers, even though the distance between electron collisions (scattering) is 1 nm. A study by the College of Nanoscale Science and Engineering (CNSE) presented at the 2013 EUVL Workshop indicated that, as a measure of EUV photoelectron and secondary electron blur, 50–100 eV electrons easily penetrated beyond 15 nm of resist thickness (PMMA or commercial resist), indicating more than 30 nm range of resist affected centered on the EUV point of absorption, for doses exceeding 200–300 uC/cm2. This can be compared with the image contrast degradation reported for sub-40 nm pitches later in 2015.
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It may be, for example, a compound of lithium bis(fluorosulfonyl)imide (LiFSI) and high molecular weight poly(ethylene oxide) (PEO), or a high molecular weight poly(trimethylene carbonate) (PTMC). The performance of these proposed electrolytes is usually measured in a half-cell configuration against an electrode of metallic lithium, making the system a "lithium-metal" cell, but it has also been tested with a common lithium-ion cathode material such as lithium-iron-phosphate (LiFePO4). Other attempts to design a polymer electrolyte cell include the use of inorganic ionic liquids such as 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) as a plasticizer in a microporous polymer matrix like poly(vinylidene fluoride-co- hexafluoropropylene)/poly(methyl methacrylate) (PVDF-HFP/PMMA).
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The Effect of Diffusion on Environmental Stress Crack Initiation in PMMA. Journal of Materials Science 33 (1998) p 5193 – 5204 The action of either a tensile stress or a corrosive liquid alone would not be enough to cause failure, but in ESC the initiation and growth of a crack is caused by the combined action of the stress and a corrosive environmental liquid. These corrosive environmental liquids are called 'secondary chemical agents', are often organic, and are defined as solvents not anticipated to come into contact with the plastic during its lifetime of use. Failure is rarely associated with primary chemical agents, as these materials are anticipated to come into contact with the polymer during its lifetime, and thus compatibility is ensured prior to use.
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Lichtenberg figure: high voltage dielectric breakdown in an acrylic polymer block Poly(methyl methacrylate) (PMMA), also known as acrylic, or acrylic glass, as well as by the trade names Crylux, Plexiglas acrylic, Acrylite, Astariglas, Lucite, Perclax, and Perspex, among several others (see below), is a transparent thermoplastic often used in sheet form as a lightweight or shatter-resistant alternative to glass. The same material can be used as a casting resin or in inks and coatings, among many other uses. Although not a type of familiar silica-based glass, the substance, like many thermoplastics, is often technically classified as a type of glass (in that it is a non- crystalline vitreous substance) hence its occasional historic designation as acrylic glass. Chemically, it is the synthetic polymer of methyl methacrylate.
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Often confused with SPEs, quasi-solid-state electrolytes (QSSEs) are also called gel polymer electrolytes (GPEs), but they have a substantially different ionic conduction mechanism: SPEs conducts ions through the interaction with the susbtitutional groups of the polymer chains, while GPEs conducts ions mainly in the solvent or plasticizer. They consist of a polymer network swollen in a solvent that contains the active ions, so it possesses both the mechanical properties of solids and the high transport properties of liquids. Several GPEs with a number of polymer hosts have been studied, by using the same polymers as SPEs (e.g. PEO, PAN, PMMA, PVDF-HFP, ...), but synthetized with increased porosity in order to easily allocate a low-evaporation solvents like ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), used as plasticizers.
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Modern Lichtenberg figures can also be created within solid insulating materials, such as acrylic (polymethyl methacrylate or PMMA) or glass by injecting them with a beam of high speed electrons from a linear electron beam accelerator (or Linac, a type of particle accelerator). Inside the Linac, electrons are focused and accelerated to form a beam of high speed particles. Electrons emerging from the accelerator have energies up to 25 MeV and are moving at an appreciable fraction (95 - 99+ percent) of the speed of light (relativistic velocities). Lichtenberg figure captured in an acrylic block If the electron beam is aimed towards a thick acrylic specimen, the electrons easily penetrate the surface of the acrylic, rapidly decelerating as they collide with molecules inside the plastic, finally coming to rest deep inside the specimen.
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Main components of a hip prosthesis A titanium hip prosthesis, with a ceramic head and polyethylene acetabular cup The modern artificial joint owes much to the 1962 work of Sir John Charnley at Wrightington Hospital. His work in the field of tribology resulted in a design that almost completely replaced the other designs by the 1970s. Charnley's design consisted of three parts: # stainless steel one-piece femoral stem and head # polyethylene (originally Teflon), acetabular component, both of which were fixed to the bone using # PMMA (acrylic) bone cement The replacement joint, which was known as the Low Friction Arthroplasty, was lubricated with synovial fluid. The small femoral head () was chosen for Charnley's belief that it would have lower friction against the acetabular component and thus wear out the acetabulum more slowly.
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In the late 1970s, tooth adhesion phosphate monomer: 2-methacryloyloxethyl phenyl hydrogen phosphate (Phenyl-P) was developed for tooth substance saving restoration technique.J. Yamauchi, N. Nakabayashi, E. Masuhara, “Adhesive Agents for Hard Tissue Containing Phosphoric Acid Monomers”, ACS Polymer Preprints, Vol. 2 (1), 594-595 (1979). 4-Methacryloyloxyethyl trimellitic acid anhydride (4-META) that adhere to not only tooth structures but also dental alloys, was developed almost at the same time.M. Takeyama, S. Kashibuchi, N. Nakabayashi, E. Masuhara, ”Studies on Dental Self-Curing Resins (17). Adhesion of PMMA with Bovine Enamel or Dental Alloys”, Journal of the Japan Society for Dental Apparatus and Materials, 19（47）179-185 (1978)． In order to create adhesive monomers having higher performance, investigation and optimization of adhesive monomer molecular structure was carried out.
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Plaque at St Thomas' Hospital - site of first permanent insertion of an intraocular lens, 8 February 1950 Sir Harold Ridley was the first to successfully implant an intraocular lens on 29 November 1949, at St Thomas' Hospital at London. That lens was manufactured by the Rayner company of Brighton, East Sussex, England from Perspex CQ polymethylmethacrylate (PMMA) made by ICI (Imperial Chemical Industries). It is said the idea of implanting an intraocular lens came to him after an intern asked him why he was not replacing the lens he had removed during cataract surgery. The acrylic plastic material was chosen because Ridley noticed it was inert after seeing RAF (Royal Air Force) pilots of World War II with pieces of shattered canopies in their eyes (this acrylic resin is known by several trade names including Lucite and Plexiglas).
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Oak Ridge National Laboratory - New Oak Ridge company putting hybrid solar lighting on map Sunlight Direct- Architectural Design Information However, this system was taken off the market in 2009. In view of the usually small diameter of the fibers, an efficient daylighting set-up requires a parabolic collector to track the sun and concentrate its light. Optical fibers intended for light transport need to propagate as much light as possible within the core; in contrast, optical fibers intended for light distribution are designed to let part of the light leak through their cladding.Use Of Diffusive Optical Fibers For Plant Lighting Optical fibers are also used in the Bjork system sold by Parans Solar Lighting AB.Parans Bjork Parans Bjork system review by Inhabitat The optic fibers in this system are made of PMMA (PolyMethylMethAcrylate) and sheathed with Megolon, a halogen-free thermoplastic resin.
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X-Ray LIGA is a fabrication process in microtechnology that was developed in the early 1980s by a team under the leadership of Erwin Willy Becker and Wolfgang Ehrfeld at the Institute for Nuclear Process Engineering (Institut für Kernverfahrenstechnik, IKVT) at the Karlsruhe Nuclear Research Center, since renamed to the Institute for Microstructure Technology (Institut für Mikrostrukturtechnik, IMT) at the Karlsruhe Institute of Technology (KIT). LIGA was one of the first major techniques to allow on- demand manufacturing of high-aspect-ratio structures (structures that are much taller than wide) with lateral precision below one micrometer. In the process, an X-ray sensitive polymer photoresist, typically PMMA, bonded to an electrically conductive substrate, is exposed to parallel beams of high-energy X-rays from a synchrotron radiation source through a mask partly covered with a strong X-ray absorbing material. Chemical removal of exposed (or unexposed) photoresist results in a three-dimensional structure, which can be filled by the electrodeposition of metal.
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PMI Colleges has consistently complied with the standards set by the Commission on Higher Education (CHED), the Technical Education and Skills Development Authority (TESDA), the International Maritime Organization (IMO) Philippine Merchant Marine Academy (PMMA)Philippine Navy UKAS Management Systems and the Standard of Training, Certification and Watchkeeping for Seafarers (STCW ’95). PMI Colleges was awarded an ISO 9001:2000 Certification for its maritime education, customs administration, and postgraduate studies in customs administration in 2005. The ISO 9001:2000 Certification is an assurance to its students of quality management system leading to effective school governance and policies towards relevant and quality learning. It also runs parallel to the vision and mission of PMI Colleges to be a center of excellence in maritime and customs education in the Philippines as well as in the Southeast Asian region to be able to continuously produce the best marine and customs officers in the world. PMI Colleges’ quality management system for its maritime education was previously accredited and certified by Det Norske Veritas (DNV).
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