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排序方式: 共有407条查询结果,搜索用时 31 毫秒
61.
This paper evaluates the quantum yield and electrical energy per order (E(Eo)) efficiency of Reactive Orange 4 (RO4) and Reactive Yellow 14 (RY14) azo dyes by three advanced oxidation processes (AOPs). Both dyes were completely decolourised by all these processes. The relative decolourisation efficiencies of these processes were in the following order: Fe(2+)/H(2)O(2)/UV>UV/TiO(2)>UV/H(2)O(2). The low efficiency of UV/H(2)O(2) process is mainly due to low UV absorption by hydrogen peroxide at the 365nm. The figure of merit E(Eo) values showed that UV/H(2)O(2) process consumes more electrical energy than the other two processes. The electrical energy consumption is in the following order: UV/H(2)O(2)>UV/TiO(2)>Fe(2+)/H(2)O(2)/UV. At low initial dye concentration higher quantum yield was observed in UV/TiO(2) process, whereas in photo-Fenton process higher quantum yield was observed at high initial dye concentration. The structure of dye molecule also influences the quantum yield and E(Eo) value. 相似文献
62.
A new class of poly(benzylidene phosphoramide ester)s containing a photoreactive benzylidene chromophore in the main chain were synthesized from bis(4-hydroxy-3-methoxy benzylidene) acetone with various substituted N-aryl phosphoramidic dichlorides by an interfacial polycondensation technique. The synthesized polymers were characterized by inherent viscosity, IR, and 1H-, 13C-, and 31P-NMR spectroscopy. The molecular weights of these polymers were determined by gel permeation chromatography. These polymers were studied for their thermal stability and photochemical properties. Thermal properties were evaluated by thermogravimetric analysis and differential scanning calorimetry. It was found that halogen-containing polymers show a higher thermal stability than that of nonhalogenated polymers. The photocrosslinking property of these polymers was studied by ultraviolet spectroscopy. The photoreactive benzylidene chromophore in the main chain dimerizes via 2π + 2π cycloaddition reaction to form a cyclobutane derivative and leads to crosslinking. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2151–2157, 1997 相似文献
63.
B. Subramanian V. Swaminathan M. Jayachandran 《Metals and Materials International》2012,18(6):957-964
Thin films of Zirconium Nitride (ZrN) were deposited by DC magnetron sputtering. The structure of the films was examined by X-ray diffraction and the crystallographic parameters were refined by Rietveld analysis. The columnar micro-structure was observed via cross-sectional SEM analysis. Defect induced, first order spectra were observed from Laser Raman studies. XPS showed the presence of Zr (N,O) ZrO2 phases on the surface of the film. The pitting corrosion was substantially reduced by the employment of Zr film as an interlayer. Corrosion tests revealed that ZrN films with a Zr interlayer exhibited clear passivation characteristics with considerably better corrosion resistance than the film without an interlayer. 相似文献
64.
Srinivasan Swaminathan Keiichiro Oh-Ishi Alexander P. Zhilyaev Christian B. Fuller Blair London Murray W. Mahoney Terry R. McNelley 《Metallurgical and Materials Transactions A》2010,41(3):631-640
The stir zone (SZ) temperature cycle was measured during the friction stir processing (FSP) of NiAl bronze plates. The FSP
was conducted using a tool design with a smooth concave shoulder and a 12.7-mm step-spiral pin. Temperature sensing was accomplished
using sheathed thermocouples embedded in the tool path within the plates, while simultaneous optical pyrometry measurements
of surface temperatures were also obtained. Peak SZ temperatures were 990 °C to 1015 °C (0.90 to 0.97 T
Melt) and were not affected by preheating to 400 °C, although the dwell time above 900 °C was increased by the preheating. Thermocouple
data suggested little variation in peak temperature across the SZ, although thermocouples initially located on the advancing
sides and at the centerlines of the tool traverses were displaced to the retreating sides, precluding direct assessment of
the temperature variation across the SZ. Microstructure-based estimates of local peak SZ temperatures have been made on these
and on other similarly processed materials. Altogether, the peak-temperature determinations from these different measurement
techniques are in close agreement. 相似文献
65.
G. Ghiasi N.A.K. Doan N. Swaminathan B. Yenerdag Y. Minamoto M. Tanahashi 《International Journal of Hydrogen Energy》2018,43(16):8105-8115
Direct numerical simulation (DNS) data of freely propagating turbulent premixed flame of stoichiometric hydrogen air mixture inside a closed vessel is analysed to study a sub-grid combustion closure based on unstrained flamelet approach. This modeling framework needs closures for the sub-grid scale (SGS) reaction rate and scalar dissipation rate. The results show that the closure models for these two SGS quantities work quite well. The dissipation rate closure involves a scale dependent parameter, , which is related to the flame curvature induced effects. The reactivity of reactant mixture increases with time in isochoric combustion because the mixture temperature and pressure increase with time. This also influences the parameter and thus the dynamic evaluation of this parameter is investigated using the DNS data. 相似文献
66.
A. P. Zhilyaev S. Swaminathan A. A. Gimazov T. R. McNelley T. G. Langdon 《Journal of Materials Science》2008,43(23-24):7451-7456
The microstructure and microhardness of copper subjected to large strains either using one or a combination of severe plastic deformation (SPD) processing techniques was evaluated. The individual SPD techniques used include equal-channel angular pressing (ECAP), high-pressure torsion (HPT), and chip formation during machining (M). Microstructural characterization using orientation imaging microscopy provided detailed information on the grain sizes and misorientation statistics after different processing routes. Vickers indentation analysis was used to evaluate the hardness of the deformed samples. The results show that excellent microstructures and properties are achieved when these three processes are used in combination, including grain sizes in the range of ~0.2–0.3 μm and hardness values up to >1,900 MPa. 相似文献
67.
In the structural analysis of proteins via X-ray diffraction, a rate-limiting step is in favourable nucleation, a problematic obstacle in successful generation of protein crystals. Here graphene and graphene oxide were applied to protein crystallisation trials, offering improvements in crystalline output and nucleation. 相似文献
68.
Electrochemical investigation of chromium nanocarbide coated Ti–6Al–4V and Co–Cr–Mo alloy substrates
Viswanathan Swaminathan Haitong Zeng Daniel Lawrynowicz Zongtao Zhang Jeremy L. Gilbert 《Electrochimica acta》2012
This study investigated the electrochemical behavior of chromium nano-carbide cermet coating applied on Ti–6Al–4V and Co–Cr–Mo alloys for potential application as wear and corrosion resistant bearing surfaces. The cermet coating consisted of a highly heterogeneous combination of carbides embedded in a metal matrix. The main factors studied were the effect of substrate (Ti–6Al–4V vs. Co–Cr–Mo), solution conditions (physiological vs. 1 M H2O2 of pH 2), time of immersion (1 vs. 24 h) and post coating treatments (passivation and gamma sterilization). The coatings were produced with high velocity oxygen fuel (HVOF) thermal spray technique at atmospheric conditions to a thickness of 250 μm then ground and polished to a finished thickness of 100 μm and gamma sterilized. Native Ti–6Al–4V and Co–Cr–Mo alloys were used as controls. The corrosion behavior was evaluated using potentiodynamic polarization, mechanical abrasion and electrochemical impedance spectroscopy under physiologically representative test solution conditions (phosphate buffered saline, pH 7.4, 37 °C) as well as harsh corrosion environments (pH ~ 2, 1 M H2O2, T = 65 °C). Severe environmental conditions were used to assess how susceptible coatings are to conditions that derive from possible crevice-like environments, and the presence of inflammatory species like H2O2. SEM analysis was performed on the coating surface and cross-section. The results show that the corrosion current values of the coatings (0.4–4 μA/cm2) were in a range similar to Co–Cr–Mo alloy. The heterogeneous microstructure of the coating influenced the corrosion performance. It was observed that the coating impedances for all groups decreased significantly in aggressive environments compared with neutral and also dropped over exposure time. The low frequency impedances of coatings were lower than controls. Among the coated samples, passivated nanocarbide coating on Co–Cr–Mo alloy displayed the least corrosion resistance. However, all the coated materials demonstrated higher corrosion resistance to mechanical abrasion compared to the native alloys. 相似文献
69.
70.
Ho D Fitzgerald M Bartlett CA Zdyrko B Luzinov IA Dunlop SA Swaminathan Iyer K 《Nanoscale》2011,3(3):907-910
RADA16 self-assembling peptide nanofiber scaffolds (SAPNSs) have been shown to have positive effects on neural regeneration following injury to the central nervous system in vivo, but mechanisms are unclear. Here we show that RADA16 SAPNSs form scaffolds of increasing fiber density with increasing peptide concentration which in turn has a concentration-dependent effect on neurons and astrocytes in mixed retinal cultures. Importantly, we report that the final nanoscale fiber architecture is an important factor to consider in designing scaffolds to promote regeneration in the central nervous system. 相似文献