Home About us Contact
|
Home About us Contact | ||
|
|
||
Optical Transparency (optical + transparency)
Kinds of Optical Transparency Selected AbstractsWaterborne, Nanocomposite Pressure-Sensitive Adhesives with High Tack Energy, Optical Transparency, and Electrical Conductivity,ADVANCED MATERIALS, Issue 20 2006T. Wang Transparent and conductive pressure-sensitive adhesives are cast from aqueous colloidal dispersions of poly(butyl acrylate) (P(BuA)) and functionalized carbon nanotubes (CNTs). At the percolation threshold for network formation (at only 0.3,wt,% functionalized CNT), the nanotubes remarkably double the amount of strain at adhesive failure and increase the adhesion energy by 85,% (see figure). The tack properties are explained by current models of adhesive debonding. [source] Nucleation kinetics and growth of nonlinear optical bis (dimethyl sulfoxide) manganese mercury thiocyanate single crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2008C. M. Raghavan Abstract Nonlinear optical (NLO) material of bis (dimethyl sulfoxide) manganese mercury thiocyanate (MMTD) was synthesized by two step reaction method. The solubility and metastable zonewidth were experimentally determined in order to optimize the growth parameters. Bulk crystals of MMTD were grown by slow cooling and slow evaporation methods. The structure of the grown crystal was confirmed by X-ray diffraction analysis. Presence of functional groups and the coordination of Lewis base ligand of dimethyl sulfoxide (DMSO) were confirmed by FT-IR analysis. Optical transparency of the grown crystals was studied by UV-Vis spectroscopy. Nonlinear optical property of the grown crystal was confirmed by Kurtz powder method. Etching studies reveal the formation of triangular hillock etch patterns, indicative of 2D nucleation mechanism. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Introduction of pH-sensitivity into mechanically strong nanoclay composite hydrogels based on N -isopropylacrylamideJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2008Siddharthya K. Mujumdar Abstract pH-sensitive nanoclay composite hydrogels based on N -isopropylacrylamide (NIPA) were synthesized by copolymerization with cationic and anionic comonomers. Laponite nanoclay particles served as multifunctional crosslinkers, producing hydrogels with exceptionally high mechanical strengths, as measured by elongation at break. Cationic copolymer gels based on NIPA and dimethylaminoethylmethacrylate were prepared by aqueous free radical polymerization, adopting a procedure reported by Haraguchi (Adv Mater 2002, 14, 1120,1124). Without modification, this technique failed to produce anionic copolymer gels of NIPA and methacrylic acid (MAA), due to flocculation of clay particles. Three methods were conceived to incorporate acidic MAA into nanoclay hydrogels. First, NIPA was copolymerized with sodium methacrylate under dilute conditions, producing hydrogels with good pH-sensitivity but weak mechanical characteristics. Second, NIPA was copolymerized with methyl methacrylate, which was then hydrolyzed to generate acid sidegroups, yielding hydrogels that were much stronger but less pH sensitive. Third, NIPA was copolymerized with MAA following modification of the nanoclay surface with pyrophosphate ions. The resulting hydrogels exhibited both strong pH-sensitivities at 37 °C and excellent tensile properties. Optical transparency changed during polymerization, depending on hydrophobicity of the components. This work increases the diversity and functionality of nanoclay hydrogels, which display certain mechanical advantages over conventionally crosslinked hydrogels. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6630,6640, 2008 [source] AER lecture: Some reflections on corneal thicknessACTA OPHTHALMOLOGICA, Issue 2007N EHLERS The corneal thickness as an object for studies was recognized in the renaissance. A value of 1 mm, representing the maximally swollen human cornea, was reported. Optical in vivo measurements were done by Blix in 1880 reporting a thickness of about 0.5 mm, the value that we today know is correct. Blix lived in "the golden age of physiologic optics". His interest was the contribution of the cornea to the optical refraction of the eye, and was thus the distance between the anterior and the posterior surface rather than the thickness of the cornea as such. A biomechanical interest in corneal thickness was initiated by the studies of tonometry, in particular Hans Goldmann's development of applanation tonometry. He predicted correctly that corneal thickness would influence the estimated pressure reading. Another physiological aspect of the cornea is its transparency. Earlier explanations by equal refractive index was revolutionized by the interference theory by David Maurice. Optical transparency required a regular fiber pattern, and thus a stabilized thickness and stromal hydration. This led to extensive interest in the permeability of the limiting layers, in particular the transport of fluid across the endothelium. The physiological concepts required a regulated or stabilized thickness. The thickness as such became interesting. The human cornea is thinner in the center than more peripherally and the central, presumably regulated central thickness (CCT) became a biometric and clinical study object. The exact individual value became of interest. Several optical and later ultrasonic principles were presented. Questions addressed were: Is CCT a life-long, age independent characteristics. Is CCT diagnostic for certain disease conditions (e.g. Macular dystrophy of Groenouw). Is CCT a useful clinical parameter to follow disease processes (e.g. progression in keratoconus or acute changes in graft rejections). Today refractive surgery has revived the interest in biomechanical and optical properties of the cornea. Modern computer technology allows for a description of the "thickness profile" of the entire cornea. This gives us access to an overwhelming amount of data, and reopen many issues of the past. We must realize, however, that what we see is the pendulum swinging back to the problems of the last century. The machinery is smarter but many of the basic questions remain to be solved. [source] Symmetric Versus Unsymmetric Platinum(II) Bis(aryleneethynylene)s with Distinct Electronic Structures for Optical Power Limiting/Optical Transparency Trade-off OptimizationADVANCED FUNCTIONAL MATERIALS, Issue 4 2009Guijiang Zhou Abstract A new series of symmetric and unsymmetric Pt(II) bis(acetylide) complexes of the type DC,CPt(PBu3)2C,CD (DPtD), AC,CPt(PBu3)2C,CA (APtA) and DC,CPt(PBu3)2C,CA (DPtA) (D, donor groups; A, acceptor groups) are synthesized, and show superior optical power limiting (OPL)/optical transparency trade-offs. By tailoring the electronic properties of the aryleneethynylene group, distinct electronic structures for these metalated complexes can be obtained, which significantly affect their photophysical behavior and OPL properties for a nanosecond laser pulse at 532,nm. Electronic influence of the ligand type and the molecular symmetry of metal group on the optical transparency/nonlinearity optimization is thoroughly elucidated. Generally, aryleneethynylene ligands with , electron-accepting nature will effectively enhance the harvesting efficiency of the triplet excited states. The ligand variation to the OPL strength of these Pt(II) compounds follows the order: DPtD,>,DPtA,>,APtA. These results could be attributed to the distinctive excited state character induced by their different electronic structures, on the basis of the data from both photophysical studies and theoretical calculations. All of the complexes show very good optical transparencies in the visible-light region and exhibit excellent OPL responses with very impressive figure of merit ,ex/,o values (up to 17), which remarkably outweigh those of state-of-the-art reverse saturable absorption dyes such as C60 and metallophthalocyanines with very poor transparencies. Their lower optical-limiting thresholds (0.05,J,cm,2 at 92% linear transmittance) compared with that of the best materials (ca. 0.07,J,cm,2 for InPc and PbPc dyes) currently in use will render these highly transparent materials promising candidates for practical OPL devices for the protection of human eyes and other delicate electro-optic sensors. [source] Optical Power Limiters Based on Colorless Di-, Oligo-, and Polymetallaynes: Highly Transparent Materials for Eye Protection Devices,ADVANCED FUNCTIONAL MATERIALS, Issue 6 2007G.-J. Zhou Abstract The synthesis, characterization, and photophysics of a series of solution-processable and tractable di-, oligo-, and polymetallaynes of some group 10,12 transition metals are presented. Most of these materials are colorless with very good optical transparencies in the visible spectral region and exhibit excellent optical power limiting (OPL) for nanosecond laser pulse. Their OPL responses outweigh those of the state-of-the-art reverse saturable absorption dyes such as C60, metalloporphyrins, and metallophthalocyanines that are all associated with very poor optical transparencies. On the basis of the results from photophysical studies and theoretical calculations, both the absorption of triplet and intramolecular charge-transfer states can contribute to the enhancement of the OPL properties for these materials. Electronic influence of the type, spatial arrangement, and geometry of metal groups on the optical transparency/nonlinearity optimization is evaluated and discussed in detail. The positive contribution of transition metal ions to the OPL of these compounds generally follows the order: Pt,>,Au,>,Hg,>,Pd. The optical-limiting thresholds for these polymetallaynes can be as low as 0.07,J,cm,2 at 92,% linear transmittance and these highly transparent materials manifest very impressive figure of merit ,ex/,o values (up to 22.48), which are remarkably higher than those of the benchmark C60 and metal phthalocyanine complexes. The present work demonstrates an attractive approach to developing materials offering superior OPL/optical transparency trade-offs and these metallopolyynes are thus very promising candidates for use in practical OPL devices for the protection of human eyes and other delicate optical sensors. [source] Colorless polyimide nanocomposite films: Thermomechanical properties, morphology, and optical transparencyJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Hyo-Seong Jin Abstract Polyimide (PI)/organoclay hybrid films were prepared by the solution intercalation method, using dodecyltriphenylphosphonium-mica (C12PPh-Mica) as the organoclay. The variations with organoclay content of the thermomechanical properties, morphology, and optical transparency of the hybrids were examined for concentrations from 0 to 1.0 wt %. For low clay contents (, 0.5 wt %), the clay particles are better dispersed in the matrix polymer, without the formation of large agglomerates of particles, than they are for high clay contents. However, agglomerated structures form and become denser in the PI matrix for clay contents , 0.75 wt %. This is in agreement with the observed trends in the thermomechanical properties and the optical transparency, which worsen drastically when the clay content of the C12PPh-Mica/PI hybrids reaches 0.75 wt %. However, when the amount of organoclay in the hybrid is 0.75 wt %, the initial modulus of the hybrid film is at its maximum value. The PI hybrid films were found to exhibit excellent optical transparencies and to be almost colorless. It was found, however, that the transparency decreases slightly with increases in the organoclay content because of agglomeration of the clay particles. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Automated image-based phenotypic analysis in zebrafish embryosDEVELOPMENTAL DYNAMICS, Issue 3 2009Andreas Vogt Abstract Presently, the zebrafish is the only vertebrate model compatible with contemporary paradigms of drug discovery. Zebrafish embryos are amenable to automation necessary for high-throughput chemical screens, and optical transparency makes them potentially suited for image-based screening. However, the lack of tools for automated analysis of complex images presents an obstacle to using the zebrafish as a high-throughput screening model. We have developed an automated system for imaging and analyzing zebrafish embryos in multi-well plates regardless of embryo orientation and without user intervention. Images of fluorescent embryos were acquired on a high-content reader and analyzed using an artificial intelligence-based image analysis method termed Cognition Network Technology (CNT). CNT reliably detected transgenic fluorescent embryos (Tg(fli1:EGFP)y1) arrayed in 96-well plates and quantified intersegmental blood vessel development in embryos treated with small molecule inhibitors of anigiogenesis. The results demonstrate it is feasible to adapt image-based high-content screening methodology to measure complex whole organism phenotypes. Developmental Dynamics 238:656,663, 2009. © 2009 Wiley-Liss, Inc. [source] Underivatized cyclic olefin copolymer as substrate material and stationary phase for capillary and microchip electrochromatographyELECTROPHORESIS, Issue 15 2008Omar Gustafsson Abstract We report, for the first time, the use of underivatized cyclic olefin copolymer (COC, more specifically: Topas) as the substrate material and the stationary phase for capillary and microchip electrochromatography (CEC), and demonstrate chromatographic separations without the need of coating procedures. Electroosmotic mobility measurements in a 25,,m id Topas capillary showed a significant cathodic EOF that is pH-dependent. The magnitude of the electroosmotic mobility is comparable to that found in glass substrates and other polymeric materials. Open-tubular CEC was employed to baseline-separate three neutral compounds in an underivatized Topas capillary with plate heights ranging from 5.3 to 12.7,,m. The analytes were detected using UV absorbance at 254,nm, thus taking advantage of the optical transparency of Topas at short wavelengths. The fabrication of a Topas-based electrochromatography microchip by nanoimprint lithography is also presented. The microchip has an array of pillars in the separation column to increase the surface area. The smallest features that were successfully imprinted were around 2,,m wide and 5,,m high. No plasma treatment was used during the bonding, thus keeping the surface properties of the native material. An RP microchip electrochromatography separation of three fluorescently labeled amines is demonstrated on the underivatized microchip with plate heights ranging from 3.4 to 22,,m. [source] Oxygen-Terminated Nanocrystalline Diamond Film as an Efficient Anode in PhotovoltaicsADVANCED FUNCTIONAL MATERIALS, Issue 8 2010Candy Haley Yi Xuan Lim Abstract The potential of using p-doped nanocrystalline diamond as the anode for organic solar cells, because of its outstanding photostability and well-matched energetics with organic dyes, is demonstrated. The interface dipole and open-circuit potential can be tuned by varying the surface termination on diamond. Oxygenated nanocrystalline diamond (O-NCD) exhibits the best photocurrent conversion among all the surface-treated electrodes studied in this work because of its large open-circuit potential. The good energy alignment of the valence band of O-NCD with the HOMO of poly(3-hexylthiophene), as well as its p-doped characteristics, suggest that O-NCD can replace the hole transport layer, such as PEDOT:PSS, needed for efficient performance on indium tin oxide (ITO) electrodes. If the sheet resistance and optical transparency on NCD can be further optimized, chemical-vapor-deposited diamond electrodes may offer a viable alternative to ITO and fluorinated tin oxide (FTO). [source] Optical Power Limiters: Symmetric Versus Unsymmetric Platinum(II) Bis(aryleneethynylene)s with Distinct Electronic Structures for Optical Power Limiting/Optical Transparency Trade-off Optimization (Adv. Mater.ADVANCED FUNCTIONAL MATERIALS, Issue 4 20098/2009) The development of symmetric and unsymmetric platinum(II) bis(acetylide)s as highly transparent optical limiters is described by Wong and co-workers on page 531. Their excited state character is governed by electronic structure, which significantly affects their photophysical properties and optical power limiting (OPL) behavior. The sound OPL responses and low OPL thresholds together with their excellent optical transparency render these materials very promising candidates for practical devices for the protection of human eyes and other delicate electro-optic sensors. [source] Supported Lipid Bilayer on Nanocrystalline Diamond: Dual Optical and Field-Effect Sensor for Membrane DisruptionADVANCED FUNCTIONAL MATERIALS, Issue 1 2009Priscilla Kailian Ang Abstract It is demonstrated that a good biomimetic model lipid membrane with dynamic fluidity can be established on optically transparent nanocrystalline diamond (OTND) with surface roughness below 10,nm. Maigainin II, an antimicrobial peptide, is chosen to investigate the permeation of artificial bacterial membranes constructed on OTND. Due to the unique combination of optical transparency and highly sensitive surface conducting channel, intrinsic OTND affords the possibility of dual-mode sensing based on optical and field effect properties. This opens up new possibilities for making integrated biomolecule,semiconductor microdevices, or sensors where the binding of biomolecules can be tracked using confocal microscopy whilst the associated changes in charge density during membrane perforation can be tracked using the space charge effect in the semiconductor. Such a synergistic approach may provide a powerful methodology for the screening of specific bactericidal activity on biomimetic membrane systems. [source] Influences of Connecting Unit Architecture on the Performance of Tandem Organic Light-Emitting Devices,ADVANCED FUNCTIONAL MATERIALS, Issue 14 2007Y. Chan Abstract The present work investigates the influence of the n-type layer in the connecting unit on the performance of tandem organic light-emitting devices (OLEDs). The n-type layer is typically an organic electron-transporting layer doped with reactive metals. By systematically varying the metal dopants and the electron-transporting hosts, we have identified the important factors affecting the performance of the tandem OLEDs. Contrary to common belief, device characteristics were found to be insensitive to metal work functions, as supported by the ultraviolet photoemission spectroscopy results that the lowest unoccupied molecular orbitals of all metal-doped n-type layers studied here have similar energy levels. It suggests that the electron injection barriers from the connecting units are not sensitive to the metal dopant used. On the other hand, it was found that performance of the n-type layers depends on their electrical conductivities which can be improved by using an electron-transporting host with higher electron mobility. This effect is further modulated by the optical transparency of constituent organic layers. The efficiency of tandem OLEDs would decrease as the optical transmittance decreases. [source] High-Performance Flexible Transparent Thin-Film Transistors Using a Hybrid Gate Dielectric and an Amorphous Zinc Indium Tin Oxide ChannelADVANCED MATERIALS, Issue 21 2010Jun Liu High-performance flexible transparent thin-film transistors (TFTs) are demonstrated using amorphous zink indium tin oxide (ZITO) transparent oxide conductor electrodes, an amorphous ZITO transparent oxide semiconductor channel, and a vapor-deposited self-assembled nanodielectric (v-SAND) gate insulator. These TFTs exhibit a large field-effect mobility of 110 cm2V,1s,1, a current on/off ratio of 104, and a low operating voltage of 1.0,V, along with very good optical transparency and mechanical flexibility. [source] Flexible Inorganic/Organic Hybrid Thin-Film Transistors Using All-Transparent Component Materials,ADVANCED MATERIALS, Issue 20 2007L. Wang Inorganic-organic hybrid TFTs have been fabricated at room temperature using IAD-derived high-quality semiconducting In2O3 and a crosslinked spin-coatable polymer gate dielectric. TFTs exhibiting field-effect mobilities up to 160 cm2 V,1 s,1, on Si and 10 cm2 V,1 s,1 on PET substrates have been demonstrated. TFTs on PET combine good transport characteristics as well as optical transparency and flexibility. [source] Polymer,Clay Nanocomposites Exhibiting Abnormal Necking Phenomena Accompanied by Extremely Large Reversible Elongations and Excellent Transparency,ADVANCED MATERIALS, Issue 17 2006K. Haraguchi Soft and transparent polymer,clay nanocomposites (see figure), consisting of hydrophobic poly(2-methoxyethylacrylate) and hydrophilic inorganic clay, with a unique clay-network morphology have been synthesized by in,situ free-radical polymerization. The nanocomposites exhibit the first observation of abnormal necking behavior accompanied by extremely large reversible elongation (1000,3000,%) and excellent optical transparency, regardless of the clay content (1,30,wt,%). [source] Colorless polyimide nanocomposite films: Thermomechanical properties, morphology, and optical transparencyJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Hyo-Seong Jin Abstract Polyimide (PI)/organoclay hybrid films were prepared by the solution intercalation method, using dodecyltriphenylphosphonium-mica (C12PPh-Mica) as the organoclay. The variations with organoclay content of the thermomechanical properties, morphology, and optical transparency of the hybrids were examined for concentrations from 0 to 1.0 wt %. For low clay contents (, 0.5 wt %), the clay particles are better dispersed in the matrix polymer, without the formation of large agglomerates of particles, than they are for high clay contents. However, agglomerated structures form and become denser in the PI matrix for clay contents , 0.75 wt %. This is in agreement with the observed trends in the thermomechanical properties and the optical transparency, which worsen drastically when the clay content of the C12PPh-Mica/PI hybrids reaches 0.75 wt %. However, when the amount of organoclay in the hybrid is 0.75 wt %, the initial modulus of the hybrid film is at its maximum value. The PI hybrid films were found to exhibit excellent optical transparencies and to be almost colorless. It was found, however, that the transparency decreases slightly with increases in the organoclay content because of agglomeration of the clay particles. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Flexible nanocrystalline-titania/polyimide hybrids with high refractive index and excellent thermal dimensional stabilityJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 6 2010Guey-Sheng Liou Abstract In this study, a novel synthetic route was developed to prepare polyimide,nanocrystalline,titania hybrid optical films with a relatively high titania content (up to 50 wt %) and thickness (20,30 ,m) from soluble polyimides containing hydroxyl groups. Two series of newly soluble polyimides were synthesized from the hydroxy-substituted diamines with various commercial tetracarboxylic dianhydrides. The hydroxyl groups on the backbone of the polyimides could provide the organic,inorganic bonding and resulted in homogeneous hybrid solutions by controlling the mole ratio of titanium butoxide/hydroxyl group. AFM, SEM, TEM, and XRD results indicated the formation of well-dispersed nanocrystalline-titania. The flexible hybrid films could be successfully obtained and revealed relatively good surface planarity, thermal dimensional stability, tunable refractive index, and high optical transparency. A three-layer antireflection coating based on the hybrid films was prepared and showed a reflectance of less than 0.5% in the visible range indicated its potential optical applications. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1433,1440, 2010 [source] Novel amorphous perfluorocopolymeric system: Copolymers of perfluoro-2-methylene-1,3-dioxolane derivativesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 5 2006Yu Yang Abstract Perfluorotetrahydro-2-methylene-furo[3,4- d][1,3]dioxole (monomer I) and perfluoro-2-methylene-4-methoxymethyl-1,3-dioxolane (monomer II) are soluble in perfluorinated or partially fluorinated solvents and readily polymerize in solution or in bulk when initiated by a free-radical initiator, perfluorodibenzoyl peroxide. The copolymerization parameters have been determined with in situ19F NMR measurements. The copolymerization reactivity ratios are rI = 1.80 and rII = 0.80 in 1,1,2-trichlorotrifluoroethane at 41 °C and rI = 0.97 and rII = 0.85 for the bulk polymerization. These data show that this copolymerization pair has a good copolymerization tendency and yields nearly ideal random copolymers. The copolymers have only one glass-transition temperature from 101 to 168 °C, depending on the copolymer compositions. Melting endotherms have not been observed in their differential scanning calorimetry traces, and this indicates that all the copolymers with different compositions are completely amorphous. These copolymers are thermally stable (the initial decomposition temperatures are higher than 350 °C under an N2 atmosphere) and have low refractive indices and high optical transparency from UV to near-infrared. Copolymer films prepared by casting were flexible and tough. These properties make the copolymers ideal candidates as optical and electrical materials. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1613,1618, 2006 [source] Synthesis, characterization, and properties of novel ladderlike phosphorus-containing polysilsesquioxanesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2003Chin-Lung Chiang Abstract Novel ladderlike polysilsesquioxanes that contain phosphorus were successfully synthesized by the sol,gel method. The polysilsesquioxanes were characterized by Fourier transform infrared spectroscopy, 29Si NMR, and X-ray diffraction. The characterizations demonstrated that the polymer possesses a typical ladderlike structure. The thermogravimetric and differential scanning calorimetric data revealed that the polysilsesquioxanes possess excellent thermal stability. A kinetic analysis of thermal degradation showed that the activation energy of thermal degradation is 187 kJ/mol, according to Kissinger's method. The activation energy of thermal degradation normally increases with conversion (from 171 to 309 kJ/mol) according to Ozawa's method. The average activation energy, calculated by Ozawa's method, was 209 kJ/mol. The scanning electron microscopic photograph and Si and P mappings of ladderlike polysilsesquioxanes showed that the particles were uniformly dispersed at the molecular level and that the sizes of the polysilsesquioxane particles were less than 100 nm. The ultraviolet,visible spectra of the ladderlike polysilsesquioxanes revealed no absorbance in the range of 400,800 nm. Ladderlike polysilsesquioxanes possess excellent optical transparency and excellent flame retardance. This transmittance may be used as a criterion for identifying the formation of a homogeneous phase. These polymers have great potential in waveguide applications. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1371,1379, 2003 [source] Aqueous Corrosion of the GeSe4 Chalcogenide Glass: Surface Properties and Corrosion MechanismJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2009Yi-Fan Niu The aqueous corrosion behavior of the GeSe4 glass composition has been studied over time under various conditions (temperature and pH). The evolution of the surface topography by atomic force microscopy and properties such as surface hardness and reduced modulus, as well as the optical transmission in the 1,16 ,m window, have been measured as a function of time spent in the corrosive solution. It was found that even if the glass reacts at room temperature, its optical transparency was barely affected. Nevertheless, the durability of GeSe4 was found to be drastically affected by an increase of both temperature and pH. Furthermore, pure selenium nanoparticles were formed during the corrosion process, and the nature of these nanoparticles,amorphous or crystallized (hexagonal phase),depends on temperature. A reaction mechanism was proposed, and the activation energy of the reaction of corrosion in deionized water (47 kJ/mol) was determined from an original technique that relies on the temporal optical loss variation of a GeSe4 optical fiber placed in water at different temperatures. [source] Transparent diamond-on-glass micro-electrode arrays for ex-vivo neuronal studyPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2008M. Bonnauron Abstract We report on the fabrication of high aspect ratio diamond Micro Electrode Arrays (MEAs) grown on silicon as well as on glass substrates using an optimised nanoseeding technique and Bias Enhanced Nucleation (BEN). Such MEA systems combine high electrode reactivity and high electrical current injection limits with resiliency, biocompatibility and optical transparency of diamond surfaces. We present the technological steps for the fabrication of 2D as well as 3D diamond microelectrode arrays. The patterning issues involve the use of detonation nanodiamond particles (DND). (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Patterned transparent zinc oxide films produced by sol,gel embossingPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2008J. Rao Abstract A low cost zinc oxide embossing technique is reported as a method of fabricating structures relevant to a variety of applications. A zinc based sol,gel material was prepared from zinc acetate [Zn(C2H3O2)2], monoethanolamine [H2NC2H4OH] and isopropanol. The sol,gel was cast into a polydimethylsiloxane (PDMS) mould a track design, placed in contact with the substrate and dried under vacuum at 70 °C for 3 hours. The formed track pattern was further densified to provide a stable conductor film that retained the embossed shape. An optimum Zn sol,gel content of 0.6 M was identified. The embossed films had a transparency of greater than 83% in the visible region. The optical bandgap energy was evaluated to be 3.306 eV. The influence of ZnO sol,gel film synthesis and embossing parameters on the microstructure, morphology and optical transparency of fabricated structures is described. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Improvement in crystalline perfection, piezo-electric property and optical transparency of in-situ poled Fe,LiNbO3 single crystals by post growth annealing and polingPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 2 2005G. C. Budakoti Abstract Crystalline perfection, piezoelectric response and optical transparency of in-situ poled Fe,LiNbO3 single crystals was studied. Very low angle grain boundaries and the variations in the piezoelectric charge constant d33 were observed in the as-grown crystals. Grain boundaries were successfully removed at higher annealing temperatures but the d33 value was decreased. Low crystalline perfection and d33 were observed after poling the annealed specimen. These parameters were improved by low temperature annealing followed by very slow cooling. FTIR spectra revealed that OH, and CO32, ionic defects were present in the as-grown crystals. The OH, ion concentration was reduced, CO32, ions were removed and optical quality was improved after annealing at higher temperatures. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis and characterization of aromatic/cycloaliphatic poly(amide- imide-imide)s from bis(4-amino- 3,5-dimethylphenyl) cycloalkane derivativesPOLYMER INTERNATIONAL, Issue 8 2007Bhuvana Sowrirajalu Abstract A series of novel aromatic diamines containing cycloaliphatic moieties was synthesized by the reaction of cycloalkanones like cyclohexanone and cycloheptanone with 2,6-dimethylaniline. The tetrimide diacid was synthesized using the prepared diamine with 3,3,,4,4,-benzophenonetetracarboxylic acid dianhydride/pyromellitic dianhydride and p -aminobenzoic acid. The polymers were prepared by treating the tetrimide diacid with different aromatic diamines. The structures of the monomers and polymers were identified using elemental analysis and Fourier transform infrared, 1H NMR and 13C NMR spectroscopy. The polymers show excellent solubility. The polymers are amorphous and have high optical transparency. They also show good thermal stability and their Tg value is found to be in the range 268,305 °C. Copyright © 2007 Society of Chemical Industry [source] Preparation and properties of ternary polyimide/SiO2/polydiphenylsiloxane composite filmsPOLYMER INTERNATIONAL, Issue 11 2006Zhenping Shang Abstract A series of novel ternary polyimide/SiO2/polydiphenylsiloxane (PI/SiO2/PDPhS) composite films were prepared through co-hydrolysis and condensation between tetramethoxysilane, diphenyldimethoxysilane (DDS) and aminopropyltriethoxysilane-terminated polyamic acid, using an in situ sol,gel method. The composite films exhibited good optical transparency up to 30 wt% of total content of DDS and SiO2. SEM analysis showed that the PDPhS and SiO2 were well dispersed in the PI matrix without macroscopic separation of the composite films. TGA analysis indicated that the introduction of SiO2 could improve the thermal stability of the composite films. Dynamic mechanical thermal analysis showed that the composite films with low DDS content (5 wt%) had a higher glass transition temperature (Tg) than pure PI matrix. When the content of DDS was above 10 wt%, the Tg of the composite decreased slightly due to the plasticizing effect of flexible PDPhS linkages on the rigid PI chains. The composite films with high SiO2 content exhibited higher values of storage modulus. Tensile measurements also showed that the modulus and tensile strength of the composite films increased with increasing SiO2 content, and the composite films still retained a high elongation at break due the introduction of DDS. The density and water absorption of the composite films were also characterized. Copyright © 2006 Society of Chemical Industry [source] New silicone hydrogels based on interpenetrating polymer networks comprising polysiloxane and poly(vinyl alcohol) networksPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 4 2009V. N. Pavlyuchenko Abstract A method for the synthesis of a new silicone hydrogel as a biphase material for soft contact lenses is considered. The method is based on the synthesis of sequential interpenetrating polymer networks (IPN) and includes the following stages: (1) cross-linked silicone synthesis by the reaction of vinyl- and hydride-containing oligosiloxanes; (2) silicone network saturation with vinyl acetate and cross-linking monomer followed by UV-initiated polymerization to form an IPN comprising the silicone and cross-linked poly(vinyl acetate) (PVAc) network; (3) PVAc network alcoholysis with methanol to obtain silicone hydrogels comprising the silicone and cross-linked poly(vinyl alcohol) (PVAl). A study of hydrophilic, optical, mechanical, and structural features of the silicone hydrogels showed that optical transparency is achieved for materials with the highest density of silicone network cross-linking where the size of IPN structural units does not exceed 100,nm. The water content in hydrophilic networks of silicone hydrogel is found to be below the values typical of cross-linked PVAl, leading to non-additivity of IPN mechanical properties. Indeed, the elasticity moduli (E) of the hydrophilic and silicone networks are 0.4,0.7 and 0.7,1.8,MPa, respectively, whereas for some IPN this value reaches 3.0,MPa. The optimal parameters of synthesis providing the reduction of E to 0.8,1.6,MPa without deterioration of the required performance characteristics (optical transparency 90,92%, water content 20,39,wt%) are determined. Copyright © 2009 John Wiley & Sons, Ltd. [source] Packet OADMs for the next generation of ring networksBELL LABS TECHNICAL JOURNAL, Issue 4 2010Dominique Chiaroni The deployment of fiber-to-the-home (FTTH) technology in access networks is creating new demands on metropolitan area and backbone networks. The increasing bit rate per user and the simplification of access networks will make the traffic profile more bursty, requiring new flexible techniques at the metropolitan area network. This paper describes a ring network exploiting optical transparency and packet granularity. After a description of the packet optical add/drop multiplexer (POADM)-based network model motivated by specifications derived from expected needs, the paper addresses the advantages of the approach and the feasibility of the concept. © 2010 Alcatel-Lucent. [source] Novel Soluble Polyimide Containing 4- tert- Butyltoluene Moiety: Synthesis and CharacterizationCHINESE JOURNAL OF CHEMISTRY, Issue 11 2009Chenyi Wang Abstract Based on the synthesis of a rigid aromatic diamine, ,,, -bis(4-aminophenyl)-4-(t- butyl)toluene (1), a novel polyimide (PI) 3 was prepared from this diamine monomer and 4,4,-oxydiphthalic dianhydride via a one-step high-temperature polycondensation. FT-IR, 1H NMR and elemental analysis were used to investigate the chemical structures of 1 and 3. The results confirmed that they agreed with the proposed structures for both 1 and 3 completely. The obtained PI 3 showed excellent solubility in most common solvents such as N -methyl-2-pyrrolidinone, N,N -dimethylacetamide, N,N -dimethylformamide, chloroform, dichloromethane and tetrahydrofuran. The resulting strong and flexible film exhibited high thermal stability with the glass transition temperature at 317°C and the temperature at 10% weight loss beyond 519°C in both air and nitrogen atmospheres. Moreover, the film also showed high optical transparency, low dielectric constant (3.13 at 1 MHz), low water absorption (0.40%) and hydrophobic character. [source] | ||||||||||||||||||||||||||||||||||