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排序方式: 共有511条查询结果,搜索用时 15 毫秒
1.
R. V. Iyer K. Sooryanarayana T. N. Guru Row K. Vijayan 《Journal of Materials Science》2003,38(1):133-139
Using X-ray diffraction data, the behaviour of Kevlar 49 fibres at low temperatures, up to –100°C, has been analysed. During cooling, the basal plane of the monoclinic unit cell shrinks whereas the c- (unique, chain axis) length is not significantly affected. In contrast, in the return heating cycle to ambient temperature, the basal plane expands and contraction occurs along the chain direction. The unit cell registers a reduction in volume in both the cooling and heating cycles. Conspicuously, after a cycle of cooling and heating, the unit cell does not return to its initial volume. 相似文献
2.
Heat resistant coatings are required primarily for stacks, exhaust pipes, reactors, space crafts and similar equipments that are permanently or occasionally exposed to elevated temperatures. High-temperature coatings are generally based on silicone resin with ceramic and metallic pigments. In this study, iron oxide, cobalt oxide (thermo chromic compound) and aluminum oxide are used for the preparation of four new types of coloured pigments. The thermal resistant characteristics of these ceramic pigments were studied by differential thermal analysis, thermo gravimetric analysis and differential scanning calorimetric analysis. These ceramic pigments are found to be thermally stable up to 400 °C. 相似文献
3.
Mesoporous GaSBA-15 molecular sieves with different nSi/nGa ratios have been directly synthesized using Pluronic 123 triblock polymer as a structure-directing agent by pH-adjusting method. The mesoporous materials have been characterized using ICP-AES, XRD, N2 adsorption, 71Ga-MAS NMR, SEM and TEM. ICP-AES studies show a high amount of gallium incorporation on the silica pore walls. The structural and textural properties of calcined GaSBA-15 are characterized by XRD and N2 adsorption. 71Ga MAS NMR results demonstrate that a high amount of tetrahedral-gallium could be substituted for Si in the framework of SBA-15. TEM and FE-SEM images show the uniform pore diameter and rope-like hexagonal mesoporous structure of GaSBA-15. These GaSBA-15 materials have been used as catalysts for vapour-phase t-butylation of 1,2-dihydroxybenzene (DHB) for selective synthesis of 4-t-butylcatechol (4-TBC) under different reaction conditions. GaSBA-15(10) gave the highest 93.2% conversion of DHB and 95.7% selectivity of 4-TBC as compared with other GaSBA-15 catalysts. 相似文献
4.
Nibedita Mitra Kalyani Vijayan B. N. Pramila Bai S. K. Biswas 《Journal of the American Ceramic Society》1993,76(2):533-535
Cutting of Y2 O3 -doped TZP rods by a low-speed diamond saw introduces an unidentified, metastable phase X (x -ZrO2 ) coexisting with the tetragonal ( t -ZrO2 ) and the monoclinic ( m -ZrO2 ) phases initially present in the sample. Further mechanical deformation of the cut surface by indentation or polishing sustains the x -ZrO2 . Chemical etching removes the x -ZrO2 and increases the m -ZrO2 content. 相似文献
5.
Zinc dust and manganese powder as pigments were incorporated in epoxy-polyamide and butyl titanate medium, with different pigment volume concentration (PVC) ranging from 20 to 74. These protective coatings were coated on sand blasted mild steel substrates and immersed in 3 wt.% sodium chloride solution and the corrosion current was measured by the Tafel extrapolation method. From the corrosion current produced by these primers, the optimum level of the pigments in these binders was identified. Thus the protective performance of optimised primers was evaluated on a sand blasted mild steel surface by the Tafel polarisation method in 3 wt.% sodium chloride solution, over different periods of time. The results were found to be comparable with the salt spray test and galvanic current measurements. The manganese powder used for this investigation showed that it could be used as an alternative to zinc powder for metal rich primers. 相似文献
6.
Ontologies are currently emerging as representation techniques for overlapping compatibility context domains. The continuing need for more effective information retrieval has lead to the creation of the notions of the semantic web and personalized information management. Subsequently, the need for effective ontology visualization for design, management and browsing has arisen. Several ontology visualization tools have come out to strengthen the users’ cognitive support. The primary goal of this paper is to present a survey on recently implemented ontology visualization tools and their contributions in the enrichment of users’ cognitive support. This work also presents the preliminary results of an evaluation of three visualization tools to determine the suitability of each method for end user applications where ontologies are used as browsing aids. 相似文献
7.
Experimental measurements were made of the pH, density, bulk viscosity and electrical conductivity of aqueous solutions of sodium lauryl sulphate for a wide range of concentrations at 25°C. Also, the time-dependent interfacial tension data of this system with mutually saturated benzene phases are reported. Comparison of these data with literature values shows fair agreement in the majority of the cases and further reveals the lack of data in the earlier investigations below the critical micelle concentration of sodium lauryl sulphate in water. A detailed compilation of the data, reported in the literature since 1937, of the pH, density, bulk viscosity, electrical conductivity, surface tension, interfacial tension with benzene, surface excess concentration, surface shear viscosity, diffusivity and critical micelle concentration of the sodium lauryl sulphate system is given. The importance of this anionic surfactant system together with the various factors which influence the physical properties is examined. 相似文献
8.
The role of solid state epitaxy in the crystallization of nanocomposite cordierite glass to glass ceramic was investigated. The use of isostructural (-cordierite) seeds in cordierite glass led to a lowering in the crystallization temperature to form glass ceramic by about 50 °C compared to the unseeded glass. The use of non-isostructural seeds such as ZrO2 and TiO2 did not lower the crystallization temperature of cordierite glass to glass ceramic, and in the case of the TiO2-seeded glass the crystallization temperature increased by about 50 °C compared to the unseeded-cordierite glass. The lowering in crystallization temperature by-cordierite seeding can be attributed to the nucleation and epitaxial growth mechanism. 相似文献
9.
Pillai S. Vijayan Santhanakrishnan T. Kumar N. Suresh Rajesh R. 《Multidimensional Systems and Signal Processing》2022,33(3):879-898
Multidimensional Systems and Signal Processing - High-performance sonar systems mostly combine a large sensor array and an efficient beamformer for enhancing the overall detection capabilities and... 相似文献
10.
Rajendran Mala Antony Annie Aglin Arul Selvaraj Ruby Celsia Sivalingam Geerthika Narbahvi Kiruthika Chinnathambi VazagaPriya Kumarapillai Srinivasa Kumar 《IET nanobiotechnology / IET》2017,11(5):612
Foley catheters are inevitable in health care unit. Pathogens colonise and form biofilm on catheter causing catheter‐associated urinary tract infection. Therefore, the authors aimed to functionalise catheter to resist biofilm formation. The authors impregnated urinary catheters with a synergistic combination of antibiotics and silver nanoparticles (SNPs) to evaluate antibiofilm efficacy in vitro and in vivo. SNPs were synthesised using Spirulina platensis. Synergy between the SNPs and antibiotics was determined by the checker‐board method. In vivo efficacy of the functionalised catheters was assessed in mice. Liver and kidney function tests of mice were performed. The in vitro anti‐adherence activity of the functionalised catheters was evaluated after 2 years. Nanoparticle sizes were 42–75 nm. Synergistic activity was observed among SNPs (2 µg/ml), amikacin (6.25 µg/ml), and nitrofurantoin (31.25 µg/ml). In mice, catheters functionalised with combinations of antibiotics and SNPs exhibited no colonisation until Day 14. Blood, liver, and kidney tests were normal. After 2 years, catheters functionalised with antibiotics exhibited 25% inhibition of bacterial adhesion, and catheters functionalised with the nanoparticle‐antibiotic combination exhibited 90% inhibition. Impregnation of urinary catheters with a synergistic combination of antibiotics and SNPs is an efficient and promising method for preventing biofilm formation.Inspec keywords: catheters, drugs, silver, nanoparticles, nanomedicine, liver, kidney, blood, microorganisms, adhesion, biomechanics, cellular biophysicsOther keywords: Foley catheters, synergistic nanoparticle‐antibiotics combination, silver nanoparticles, biofilm formation resitance, health care unit, pathogens, urinary tract infection, SNP, Spirulina platensis, checker‐board method, liver function, kidney function, vitro antiadherence activity, amikacin, nitrofurantoin, blood, bacterial adhesion, size 42 nm to 75 nm, Ag 相似文献