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Potential Material (potential + material)
Selected AbstractsElectrochemical Sensors Based on Carbon NanotubesELECTROANALYSIS, Issue 23 2002Qiang Zhao Abstract Carbon nanotubes are attractive new materials. It has been about a decade since carbon nanotubes were discovered. Carbon nanotubes have many outstanding properties and have many practical or potential applications. In this short review we introduce recent advances in carbon nanotubes as potential material for electrochemical sensors. The advantages of carbon nanotubes as sensors are discussed along with future prospects. [source] In vitro evaluation of marginal and internal adaptation after occlusal stressing of indirect class II composite restorations with different resinous basesEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2003Didier Dietschi Composite inlays are indicated for large cavities, which frequently extend cervically into dentin. The purpose of this study was to compare in vitro the marginal and internal adaptation of class II fine hybrid composite inlays (Herculite, Kerr) made with or without composite bases, having different physical properties. Freshly extracted human molars were used for this study. The base extended up to the cervical margins on both sides and was made from Revolution (Kerr), Tetric flow (Vivadent), Dyract (Detrey-Dentsply) or Prodigy (Kerr), respectively. Before, during and after mechanical loading (1 million cycles, with a force varying from 50 to 100 N), the proximal margins of the inlay were assessed by scanning electron microscopy. Experimental data were analysed using non-parametric tests. The final percentages of marginal tooth fracture varied from 30.7% (no base) to 37.6% (Dyract). In dentin, percentages of marginal opening varied from 9.2% (Tetric Flow) to 30.1% (Prodigy), however, without significant difference between base products. Mean values of opened internal interface with dentin varied from 11.06% (Tetric Flow) to 28.15% (Prodigy). The present results regarding dentin adaptation confirmed that the physical properties of a base can influence composite inlay adaptation and that the medium-rigid flowable composite Tetric Flow is a potential material to displace, in a coronal position, proximal margins underneath composite inlays. [source] Optimizing preparation of NaCS,chitosan complex to form a potential material for the colon-specific drug delivery systemJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Ming-Jun Wang Abstract A novel polyelectrolyte complex (PEC) formed by sodium cellulose sulfate (NaCS) and chitosan was prepared as a candidate material for colon-specific drug delivery system. It was found in experiments that the properties of two raw materials and the process parameters, such as the degree of substitution (DS) and concentration of NaCS, the viscosity and concentration of chitosan, were very important factors on the properties of the final product,NaCS,chitosan-PEC. The preparation of NaCS,chitosan complex was optimized by using response surface methodology to evaluate the effects of these parameters on the degradation properties of NaCS,chitosan in the simulated colonic fluid (SCF). The DS of NaCS was in the range from 0.2 to 0.6, the concentration of NaCS from 2 to 4% (w/v), the viscosity of chitosan from 50 to 550 mPa s, and the concentration of chitosan from 0.5 to 1.5% (w/v). A mathematical model was developed to describe the effect of these parameters and their interactions on the degradation of NaCS,chitosan complex. The optimum operation conditions for preparing NaCS,chitosan complex were determined to DS of NaCS of 0.2, the concentration of NaCS of 4.0% (w/v), chitosan viscosity of 327 mPa s, and the concentration of chitosan 0.5% (w/v), respectively. Validation of experiments with 5 confirmatory runs indicated the high degree of prognostic ability of response surface methodology. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Improvements in the production of bacterial synthesized biocellulose nanofibres using different culture methodsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2010Amir Sani Abstract This review summarizes previous work that was done to improve the production of bacterial cellulose nanofibres. Production of biocellulose nanofibres is a subject of interest owing to the wide range of unique properties that makes this product an attractive material for many applications. Bacterial cellulose is a natural nanomaterial that has a native dimension of less than 50 nm in diameter. It is produced in the form of nanofibres, yielding a very pure cellulose product with unique physical properties that distinguish it from plant-derived cellulose. Its high surface-to-volume ratio combined with its unique properties such as poly-functionality, hydrophilicity and biocompatibility makes it a potential material for applications in the biomedical field. The purpose of this review is to summarize the methods that might help in delivering microbial cellulose to the market at a competitive cost. Different feedstocks in addition to different bioreactor systems that have been previously used are reviewed. The main challenge that exists is the low yield of the cellulosic nanofibres, which can be produced in static and agitated cultures. The static culture method has been used for many years. However, the production cost of this nanomaterial in bioreactor systems is less expensive than the static culture method. Biosynthesis in bioreactors will also be less labour intensive when scaled up. This would improve developing intermediate fermentation scale-up so that the conversion to an efficient large-scale fermentation technology will be an easy task. Copyright © 2009 Society of Chemical Industry [source] Synthesis of pH-responsive crosslinked poly[styrene- co -(maleic sodium anhydride)] and cellulose composite hydrogel nanofibers by electrospinningPOLYMER INTERNATIONAL, Issue 5 2009Shengguang Cao Abstract BACKGROUND: Stimuli-sensitive materials show enormous potential in the development of drug delivery systems. But the low response rate of most stimuli-sensitive materials limits their wider application. We propose that electrospinning, a technique for the preparation of ultrafine fibrous materials with ultrafine diameters, may be used to prepare materials with a fast response to stimuli. RESULTS: Poly[styrene- co -(maleic sodium anhydride)] and cellulose (SMA-Na/cellulose) hydrogel nanofibers were prepared through hydrolysis of precursor electrospun poly[styrene- co -(maleic anhydride)]/cellulose acetate (SMA/CA) nanofibers. In the presence of diethylene glycol, the SMA/CA composite nanofibers were crosslinked by esterification at 145 °C, and then hydrolyzed to yield crosslinked SMA-Na/cellulose hydrogel nanofibers. These nanofibers showed better mechanical strengths and were pH responsive. Their water swelling ratio showed a characteristic two-step increase at pH = 5.0 and 8.2, with the water swelling ratio reaching a maximum of 27.6 g g,1 at pH = 9.1. CONCLUSION: The crosslinked SMA-Na hydrogel nanofibers supported on cellulose showed improved dimensional stability upon immersion in aqueous solutions. They were pH responsive. This new type of hydrogel nanofiber is a potential material for biomedical applications. Copyright © 2009 Society of Chemical Industry [source] High-Surface-Area Nanoporous Boron Carbon Nitrides for Hydrogen StorageADVANCED FUNCTIONAL MATERIALS, Issue 11 2010David Portehault Abstract Nano- and mesoporous boron carbon nitrides with very high surface areas up to 1560,m2,g,1 are obtained by pyrolysis of a graphitic carbon nitride mpg-C3N4 infiltrated with a borane complex. This reactive hard-templating approach provides easy composition and texture tuning by temperature adjustment between 800 and 1400,°C. The process yields BxCyNzOvHw materials as direct copies of the initial template with controlled compositions of 0.15,,,x,,,0.36, 0.10,,,y,,,0.12, 0.14,,,z,,, 0.32, and 0.11,,,v,,,0.28. The nano and mesoporosities can also be tuned in order to provide hierarchical materials with specific surface areas ranging from 610 to 1560,m2,g,1. Such high values, coupled with resistance against air oxidation up to 700,°C, suggest potential materials for gas storage and as catalyst supports. Indeed, it is demonstrated that these compounds exhibit high and tunable H2 uptakes from 0.55 to 1.07,wt.% at 77,K and 1 bar, thus guiding further search of materials for hydrogen storage. [source] UV-photodimerization in uracil-substituted dendrimers for high density data storageJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2007Brian Lohse Abstract Two series of uracil-functionalized dendritic macromolecules based on poly (amidoamine) PAMAM and 2,2-bis(hydroxymethylpropionic acid) bis-MPA backbones were prepared and their photoinduced (2,+2,) cycloaddition reactions upon exposure to UV light at 257 nm examined. Dendrimers up to 4th generation were synthesized and investigated as potential materials for high capacity optical data storage with their dimerization efficiency compared to uracil as a reference compound. This allows the impact of increasing the generation number of the dendrimers, both the number of chromophores, as well as the different steric environments, on the performance of each series of dendrimers to be investigated. The (uracil)12 -[G-2]-bis-MPA and (uracil)8 -[G-1]-PAMAM were observed to have high dimerization efficiency in solution with different behavior being observed for the PAMAM and bis-MPA dendrimers. The dendrimers with the best dimerization efficiency in solution were then examined in the solid state as thin films cast on quartz plates, and their film qualities along with their photodimerization performance studied. High quality films with a transmission response of up to 70% in 55 s. when irradiated at 257 nm with an intensity of 70 mW/cm2 could be obtained suggesting future use as recording media for optical data storage. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4401,4412, 2007 [source] Electromagnetic interference shielding by using conductive polypyrrole and metal compound coated on fabricsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 8 2002C. Y. Lee Abstract Electromagnetic interference (EMI) shielding materials of complex type of conductive polypyrrole (PPy) as an intrinsically conducting polymer and silver-palladium (AgPd) metal compound coated on woven or non-woven fabrics are synthesized. From dc conductivity and SEM photographs of PPy/fabric complexes, we discuss charge transport mechanism and the homogeneity of coating on the fabrics. The EMI shielding efficiency of PPy/fabric and AgPd/fabric complexes is in the range of 8,,,80 dB depending on the conductivity and the additional Ag vacuum evaporation. The highest EMI shielding efficiency of PPy/fabric complexes vacuum-evaporated by Ag is ,80 dB, indicating potential materials for military uses. We propose that PPy/fabrics are excellent RF and microwave absorber because of the relatively high absorbance and low reflectance of the materials. Copyright © 2002 John Wiley & Sons, Ltd. [source] Cysteine-capped ZnSe quantum dots as affinity and accelerating probes for microwave enzymatic digestion of proteins via direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysisRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 15 2009Lokesh A. Shastri Fluorescent semiconductor quantum dots (QDs) exhibit great potential and capability for many biological and biochemical applications. We report a simple strategy for the synthesis of aqueous stable ZnSe QDs by using cysteine as the capping agent (ZnSe-Cys QDs). The ZnSe QDs can act as affinity probes to enrich peptides and proteins via direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) analysis. This nanoprobe could significantly enhance protein signals (insulin, ubiquitin, cytochrome c, myoglobin and lysozyme) in MALDI-TOFMS by 2.5,12 times compared with the traditional method. Additionally, the ZnSe-Cys QDs can be applied as heat absorbers (as accelerating probes) to speed up microwave-assisted enzymatic digestion reactions and also as affinity probes to enrich lysozyme-digested products in MALDI-TOFMS. Furthermore, after the enrichment experiments, the solutions of ZnSe-Cys QDs mixed with proteins can be directly deposited onto the MALDI plates for rapid analysis. This approach shows a simple, rapid, efficient and straightforward method for direct analysis of proteins or peptides by MALDI-TOFMS without the requirement for further time-consuming separation processes, tedious washing steps or laborious purification procedures. The present study has demonstrated that ZnSe-Cys QDs are reliable and potential materials for rapid, selective separation and enrichment of proteins as well as accelerating probes for microwave-digested reactions for proteins than the regular MALDI-MS tools. Additionally, we also believe that this work may also inspire investigations for applications of QDs in the field of MALDI-MS for proteomics. Copyright © 2009 John Wiley & Sons, Ltd. [source] | |||||||||||||