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Film Shows (film + shows)
Selected AbstractsAn Organic Sol-Gel Film as Modifier to Construct BiosensorELECTROANALYSIS, Issue 2 2009Jian-Feng Wu Abstract A new amperometric biosensor for hydrogen peroxide (H2O2) was developed by adsorbing hemoglobin (Hb) on an organic sol-gel film. The organic sol-gel was prepared using resorcinol and formaldehyde as monomers. This sol-gel film shows a biocompatible microenvironment for retaining the native activity of the adsorbed Hb. The direct electron transfer between Hb and electrode is achieved. Hb adsorbed on the film shows an enzyme-like catalytic activity for the reduction of H2O2. The reduction peak currents are proportional linearly to the concentration of hydrogen peroxide in the range of 6×10,8 to 3.6×10,6,M, with a detection limit of 2.4×10,8,M (S/N=3). This research enlarges the applications of organic sol-gel materials in biosensor field. [source] Electrochemical Preparation of Poly(Malachite Green) Film Modified Nafion-Coated Glassy Carbon Electrode and Its Electrocatalytic Behavior Towards NADH, Dopamine and Ascorbic AcidELECTROANALYSIS, Issue 14 2007Shen-Ming Chen Abstract Poly(malachite green) film modified Nafion-coated glassy carbon electrodes have been prepared by potentiodynamic cycling in malachite green solution. The pH of polymerisation solution has only minor effect on film formation. Electrochemical quartz crystal microbalance (EQCM) was used to monitor the growth of the poly(malachite green) film. Cyclic voltammogram of the poly(malachite green) film shows a redox couple with well-defined peaks. The redox response of the modified electrode was found to be depending on the pH of the contacting solution. The peak potentials were shifted to a less positive region with increasing pH and the dependence of the peak potential was found to be 56,mV per pH unit. The electrocatalytic behavior of poly(malachite green) film modified Nafion-coated glassy carbon electrodes was tested towards oxidation of NADH, dopamine, and ascorbic acid. The oxidation of dopamine and ascorbic acid occurred at less positive potential on poly(malachite green) film compared to bare glassy carbon electrode. In the case of NADH, the overpotential was reduced substantially on modified electrode. Finally, the feasibility of utilizing poly(malachite green) film electrode in analytical estimation of ascorbic acid was demonstrated in flow injection analysis. [source] Dielectric Properties of a Printed Sol,Gel Matrix Composite,ADVANCED ENGINEERING MATERIALS, Issue 5 2010Tobias Lehnert Low temperature processable materials with high dielectric constants are required for application on flexible organic substrates, for example, in printed electronics. To date, mainly organic polymers with embedded functional particles have been investigated for this purpose. For the first time, we present a printable dielectric composite material composed of ferroelectric high permittivity particles (BaTiO3) bonded by a mainly inorganic sol,gel derived network. The exemplary optimization of the properties by varying the sol,gel precursor illustrates the potential of sol,gel chemistry for printable functional materials. An operational gravure printed capacitor including printed silver electrodes is presented. The measured dielectric constants are among the highest reported in literature for low temperature cured films with moderate dissipation factors. Besides these promising dielectric properties, this composite film shows a ferroelectric response. [source] Fast High-Temperature Response of Carbon Nanotube Film and Its Application as an Incandescent DisplayADVANCED MATERIALS, Issue 35 2009Peng Liu Super aligned carbon nanotube (CNT) film shows a fast high-temperature response: the film can be heated to incandescence and cools down in about 1 ms. Using screen printing and laser cutting, an incandescent CNT film array that can dynamically display Chinese characters is fabricated. More applications of the film may be developed based on its fast response. [source] Comparison of the composition of oral mucosal residual saliva with whole salivaORAL DISEASES, Issue 6 2007J-Y Lee Objective:, Compared with whole saliva, residual saliva comprising the oral mucosal film shows a high protein concentration. The purpose of this study was to compare the composition of residual saliva with unstimulated and stimulated whole saliva in normosalivators. Materials and methods:, The composition of oral mucosal residual saliva in 30 healthy individuals was investigated and compared with that of whole saliva. The concentrations of total protein, secretory immunoglobin A (sIgA), lactoferrin, total carbohydrate, and sialic acid were examined. The activities of peroxidase, lysozyme and , -amylase were determined. Results:, Residual saliva had higher levels of total protein and carbohydrate than whole saliva, with a higher carbohydrate to protein ratio in the residual saliva suggesting that salivary glycoproteins are concentrated on the oral mucosal surface. sIgA, lactoferrin and sialic acid were present as highly concentrated forms in residual saliva. The enzymatic activity of peroxidase in residual saliva was higher than that of whole saliva. Conclusions:, These concentrated carbohydrate and antimicrobials on the oral mucosal surface work for mucosal defence and could be used for targeting sites for the delivery of therapeutic agents. [source] Development and application of an excitation ratiometric optical pH sensor for bioprocess monitoringBIOTECHNOLOGY PROGRESS, Issue 6 2008Ramachandram Badugu Abstract The development of a fluorescent excitation ratiometric pH sensor (AHQ-PEG) using a novel allylhydroxyquinolinium (AHQ) derivative copolymerized with polyethylene glycol dimethacrylate (PEG) is described. The AHQ-PEG sensor film is shown to be suitable for real-time, noninvasive, continuous, online pH monitoring of bioprocesses. Optical ratiometric measurements are generally more reliable, robust, inexpensive, and insensitive to experimental errors such as fluctuations in the source intensity and fluorophore photobleaching. The sensor AHQ-PEG in deionized water was shown to exhibit two excitation maxima at 375 and 425 nm with a single emission peak at 520 nm. Excitation spectra of AHQ-PEG show a decrease in emission at the 360 nm excitation and an increase at the 420 nm excitation with increasing pH. Accordingly, the ratio of emission at 420:360 nm excitation showed a maximum change between pH 5 and 8 with an apparent pKa of 6.40. The low pKa value is suitable for monitoring the fermentation of most industrially important microorganisms. Additionally, the AHQ-PEG sensor was shown to have minimal sensitivity to ionic strength and temperature. Because AHQ is covalently attached to PEG, the film shows no probe leaching and is sterilizable by steam and alcohol. It shows rapid (,2 min) and reversible response to pH over many cycles without any photobleaching. Subsequently, the AHQ-PEG sensor film was tested for its suitability in monitoring the pH of S. cereviseae (yeast) fermentation. The observed pH using AHQ-PEG film is in agreement with a conventional glass pH electrode. However, unlike the glass electrode, the present sensor is easily adaptable to noninvasive monitoring of sterilized, closed bioprocess environments without the awkward wire connections that electrodes require. In addition, the AHQ-PEG sensor is easily miniaturized to fit in microwell plates and microbioreactors for high-throughput cell culture applications. [source] Planarized Star-Shaped Oligothiophenes as a New Class of Organic Semiconductors for Heterojunction Solar Cells,ADVANCED MATERIALS, Issue 22 2003R. de Bettignies Although compounds 1 and 2 (see Figure) have comparable conjugation lengths, the characterization of vacuum evaporated thin solid films shows that the star-shaped geometry of compound 1 favors a preferential horizontal orientation of the molecules onto the surface of the substrate, which results in a increase of the efficiency of the corresponding heterojunction solar cells under white-light illumination by a factor of 20. [source] Effect of ion energy on structural and electrical properties of intrinsic microcrystalline silicon layer deposited in a matrix distributed electron cyclotron resonance plasma reactorPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2010Sanjay K. Ram Abstract Microcrystalline silicon films were deposited in a matrix distributed electron cyclotron resonance (MDECR) plasma enhanced chemical vapor deposition (PECVD) system using pure silane, under varying substrate bias conditions. Microstructural characterization of the films shows a lower void fraction and a preponderance of nanograins in films deposited at negative bias, while in positive bias a thin incubation layer is seen with a higher void fraction. Plasma emission studies reveal higher electron temperature and more atomic H at positive bias, which lead to early onset of crystallization. The microstructural properties of the films are correlated with the dark and phototransport properties. Our study demonstrates the importance of substrate bias in controlling the ion energy and properties of films deposited in the MDECR reactor. [source] Initiated CVD of Poly(methyl methacrylate) Thin Films,CHEMICAL VAPOR DEPOSITION, Issue 10 2005K. Chan Abstract Initiated CVD (iCVD), a dry method, is able to produce poly(methyl methacrylate) (PMMA) thin films by utilizing a reactive gaseous mixture of the monomer methyl methacrylate and the initiator triethylamine. The deposition rate is twenty times faster with the use of the initiator. Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) show high structural resemblance between iCVD PMMA and conventional PMMA, and the degree of functionality retention increases with decreasing residence time in the vacuum chamber. XPS detection of nitrogen incorporation is consistent with the incorporation of the initiator into the polymer chains. NMR spectroscopy on completely dissolved films shows that the tacticity of iCVD PMMA resembles that of conventional, radically polymerized PMMA. Altogether these observations support the hypothesis that, for iCVD PMMA, the polymerization is by a free-radical mechanism. [source] | ||||||||||