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951.
Systematic analysis about the exploitation of imidazolium based ionic liquids(ILs),[BMIM]BF4[IL1],[EMIM]BF4 [IL2]and[BMIM]PF6[IL3]as the morphological template on the basic sol-gel method adopted synthesis of nanostructured zinc oxide(ZnO) is presented.X-ray diffraction(XRD),particle size analysis(PSA) and scanning electron microscopy(SEM) have been employed for the characterization of structure and morphology of the synthesized ZnO particles.Well-defined capsule like shaped morphology with lower nanosize is observed for the ZnO nanoparticles with IL1 than those with IL2 and IL3.This confirms that IL1 served as an effective templating material due to their unique properties.Especially the effective aggregation of ZnO particles with a self-organized frame of IL1 was the essential factor to produce the lower nanosized ZnO with capsule shaped structure.The synthesized ZnO samples with IL2 and IL3 fabricated the flake like shaped and rod like shaped morphologies in the range of nanoscale.The formed ZnO nanoparticles with IL2 exhibit higher nanosize than the ZnO nanoparticles produced by IL1,owing to shorter length of alkyl group in its cation which restricts steric effect and permits the nanoparticles to grow longer.Even though IL3 produced the discrete ZnO nanorods,the hydrophobic nature of IL3 created the higher nanosize than the ZnO nanoparticles formed by other two ionic liquids.Antibacterial properties of the synthesized ZnO nanostructures were investigated against Staphylococcus aureus(gram positive) and Escherichia coli(gram negative) bacteria by Agar diffusion test method.Microbial experiments indicate that the synthesized ZnO samples show a wide spectrum of antimicrobial activities and performed better against S.aureus than E.coli with the same concentration of ZnO. 相似文献
952.
953.
Due to superior thermal properties and many potential applications, nanofluids have recently attracted the attention of the research community. Though the experiments in nanofluids have revealed the spectacular heat transfer enhancement in them, there are many inconsistencies in the reported experimental values and controversies in the mechanisms proposed for heat transport in nanofluids. This indicates that it is crucial to be aware of the different mechanisms contributing to superior thermal properties of nanofluids and discuss the existing controversies in them. Therefore, in this article, we provide an overview of the various possible mechanisms reported in the literature that contribute to enhanced thermal conductivity of nanofluids. The other factors affecting the nanofluids thermal conductivity and the mathematical models for estimating nanofluids thermal conductivity with their limitations are also discussed. 相似文献
954.
R. Suresh A. Vijayaraj K. Giribabu R. Manigandan R. Prabu A. Stephen E. Thirumal V. Narayanan 《Journal of Materials Science: Materials in Electronics》2013,24(4):1256-1263
In this paper, we report a simple synthesis of Fe2O3 nanoparticles using hydrothermal method. The formation of the sample was confirmed by X-ray diffraction analysis, X-ray photoelectron spectroscopy, Fourier transformed infrared spectroscopy, Raman spectroscopy and UV–Visible absorption spectroscopy. The average crystallite size of the synthesized Fe2O3 nanoparticles was estimated to be 61 nm and the particles were of good crystalline nature. Field emission-scanning electron microscopy study of the sample revealed that the Fe2O3 powder has rod-like morphology which is composed of nanoparticles. The vibrating sample magnetometer measurement shows that the nanoparticles possess ferromagnetic property. The synthesized Fe2O3 nanoparticles were used to modify glassy carbon electrode (Fe2O3/GCE) and the modified electrode was used to detect pyrocatechol (PC) in a pH 7.4 phosphate buffer solutions by cyclic voltammetry and chronoamperometry. At the Fe2O3/GCE, PC is oxidized at less positive potential with larger current response than the bare GCE. The proposed sensor exhibits great potential in the field of electrochemical sensing of PC. 相似文献
955.
Suresh Babu Pitchuka Bikramjit Basu G. Sundararajan 《Journal of Thermal Spray Technology》2013,22(4):478-490
In the present study, WC-12Co coatings were deposited by detonation-spraying technique using conventional and nanostructured WC-12Co feedstock at four different oxy/fuel ratios (OF ratio). The coatings exhibited the presence of phases like W2C and W due to the decarburization of the WC phase, and the proportions of these phases were higher in the nano WC-12Co coatings compared with conventional WC-12Co coatings. Coating hardness and fracture toughness were measured. The tribological performance of coatings was examined under dry sand rubber wheel abrasion wear, and solid particle erosion wear conditions. The mechanical and wear properties of coatings were influenced by degree of decarburization and more so in the case of nanostructured WC-Co coatings. The results indicate that the extent of decarburization has a substantial influence on the elastic modulus of the coating which in turn is related to the extent of intersplat cracking of the coating. 相似文献
956.
Jesumathy Stella P. Udayakumar M. Suresh S. 《Journal of Mechanical Science and Technology》2012,26(3):959-965
An energy storage system has been designed to study the heat transfer characteristics of paraffin wax during melting and solidification
processes in a vertical annulus energy storage system. In the experimental study, three important issues are focused. The
first one is temperature distribution in the phase change material (PCM) during the phase change processes. The second one
is the thermal characteristics of the paraffin wax, which includes total melting and total solidification times, the nature
of heat transfer phenomena in melted and solidified PCM and the effect of Reynolds number as inlet heat transfer fluid (HTF)
conditions on the heat transfer parameters. The final one is to calculate heat transfer coefficient and effectiveness during
solidification process. The experimental results proved that the PCM melts and solidifies congruently, and the melting front
moved from the top to the bottom of the PCM container whereas the solidification front moved from bottom to the top along
the axial distances in the PCM container. Experiment has been performed for different water flow rates at constant inlet temperature
of heat transfer fluid for recovery and use of heat. Time-based variations of the temperature distributions were explained
from the results of observations of melting and solidification curves. Charging and discharging processes were carried out.
Heat transfer characteristics were studied. 相似文献
957.
958.
Leila Hojabri Jesmy Jose Alcides Lopes Leao Laziz Bouzidi Suresh S. Narine 《Polymer》2012,53(17):3762-3771
Four aliphatic thermoplastic poly(ester-urethane)s (PEUs) with similar molecular weights but varying polyesters molecular weight (534–1488 g/mol) were prepared from polyester diols, obtained by melt condensation of Azelaic acid and 1,9-Nonanediol, and 1,7-heptamethylene di-isocyanate (HPMDI) all sourced from vegetable oil feedstock. The thermal, and mechanical properties, and crystal structure of PEUs were investigated using DSC, TGA, DMA, tensile analysis and WAXD. For sufficiently long polyester chain, WAXD data indicated no hydrogen bonds polyethylene (PE)-like crystalline packing and for short polyester chains, small crystal domains with significant H-bonded polyamide (PA)-like packing. Crystallinity decreased with decreasing polyester molecular weights. The polymorphism of PEUs and consequently their melting characteristics were found to be largely controlled by polyester segment length. TGA of the PEUs indicated improved thermal stability with decreasing polyester chain length, suggesting a stabilization effect by urethane groups. Mechanical properties investigated by DMA and tensile analysis were found to scale predictably with the overall crystallinity of PEUs. 相似文献
959.
Na+-conducting sodium dysprosium (phospho) silicates with the compositions Na5DySi4O12, Na3.9Dy0.6P0.3Si2.7O9 and Na3.9Dy0.6Si3O8.85 were synthesized by solid state route. The phase evolution in the three systems was studied as a function of heat treatment temperature from 600 °C to 1000 °C by X-ray diffraction technique. It was possible to achieve a NASICON Na5DySi4O12-type single phase with the compositions Na3.9Dy0.6P0.3Si2.7O9 and Na3.9Dy0.6Si3O8.85 at 800 °C. Heat treatment at a higher temperature (>850 °C) resulted in the formation of a less conductive Na9DySi6O18-type phase. Conventional and microwave sintering were carried out on Na3.9Dy0.6P0.3Si2.7O9 sample at 800 °C and the ionic conductivities were measured as a function of temperature from 75 °C to 325 °C. The microwave sintered sample exhibited better Na+ ionic conductivity of 0.42 × 10−2 S/cm when compared to that of conventionally sintered sample which was 0.43 × 10−3 S/cm at 325 °C. 相似文献
960.
Kar A Rehman IH Burney J Puppala SP Suresh R Singh L Singh VK Ahmed T Ramanathan N Ramanathan V 《Environmental science & technology》2012,46(5):2993-3000
Use of improved (biomass) cookstoves (ICs) has been widely proposed as a Black Carbon (BC) mitigation measure with significant climate and health benefits. ICs encompass a range of technologies, including natural draft (ND) stoves, which feature structural modifications to enhance air flow, and forced draft (FD) stoves, which additionally employ an external fan to force air into the combustion chamber. We present here, under Project Surya, the first real-time in situ Black Carbon (BC) concentration measurements from five commercial ICs and a traditional (mud) cookstove for comparison. These experiments reveal four significant findings about the tested stoves. First, FD stoves emerge as the superior IC technology, reducing plume zone BC concentration by a factor of 4 (compared to 1.5 for ND). Indoor cooking-time BC concentrations, which varied from 50 to 1000 μg m(-3) for the traditional mud cookstove, were reduced to 5-100 μg m(-3) by the top-performing FD stove. Second, BC reductions from IC models in the same technology category vary significantly: for example, some ND models occasionally emit more BC than a traditional cookstove. Within the ND class, only microgasification stoves were effective in reducing BC. Third, BC concentration varies significantly for repeated cooking cycles with same stove (standard deviation up to 50% of mean concentration) even in a standardized setup, highlighting inherent uncertainties in cookstove performance. Fourth, use of mixed fuel (reflective of local practices) increases plume zone BC concentration (compared to hardwood) by a factor of 2 to 3 across ICs. 相似文献