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排序方式: 共有793条查询结果,搜索用时 78 毫秒
1.
S. Sarika S. Abhilash V.S. Sumi S. Rijith 《International Journal of Hydrogen Energy》2021,46(30):16387-16403
A promising electrocatalyst containing variable percentage of V2O5–TiO2 mixed oxide in graphene oxide support was prepared by embedding the catalyst on Cu substrate through facile electroless Ni–Co–P plating for hydrogen evolution reaction. The solvothermal decomposition method was opted for tuning the crystalline characteristics of prepared material. The optimized mixed oxide was well characterized, active sites centres were identified and explained by X-ray diffraction, high resolution tunnelling electron microscopy, scanning electron microscopy coupled with energy dispersive X-ray and X-ray photon spectroscopy analysis. The structural and electronic characteristics of material was done by fourier transform infrared spectroscopy and the electrochemical behaviour of the prepared material was evaluated by using Tafel plot, electrochemical impedance analysis, linear sweep voltammetry, open circuit analysis and chronoamperometry measurements. The results show the enhanced catalytic activity of Ni–Co–P than pure Ni–P plate, due to synergic effect. Moreover, the prepared mixed oxide incorporated Ni–Co–P plate has a high activity towards HER with low over potential of 101 mV, low Tafel slope of 36 mVdec?1, high exchange current density of 9.90 × 10?2 Acm?2. 相似文献
2.
Motofumi Suzuki Kohei Kinoshita Shinji Jomori Hidehiko Harada Kaoru Nakajima Kenji Kimura 《Thin solid films》2007,515(22):8281-8284
The initial stage of iron silicide formation is investigated by high-resolution Rutherford backscattering spectroscopy. During the Fe deposition on Si(001) at 470 °C, the formation of FeSi2 is confirmed by the surface peak analysis. Initially, FeSi2 grows epitaxially so that one of the major crystallographic axes is parallel to the <111> axis of the Si substrate. With increasing Fe deposition, the deviation between the major crystallographic axis of the silicide region and Si<111> increases although the electron diffraction pattern is independent of the amount of Fe deposition. Therefore, the subsurface crystallographic structure of iron silicide is transformed from a cubic-like to a low-symmetry structure. 相似文献
3.
Two series of semiflexible random thermotropic copolymers containing 8‐(3‐hydroxy phenyl) octanoic acid (HPOA) with either 3‐chloro‐4‐hydroxy benzoic acid or 3,5‐dibromo‐4‐hydroxy benzoic acid were prepared by melt polycondensation techniques. The copolyesters were characterized with Fourier transform infrared spectroscopy, dilute solution viscometry, hot‐stage polarized light microscopy, differential scanning calorimetry, thermogravimetric analysis, and wide‐angle X‐ray diffraction. Studies revealed that the amount of HPOA as a disruptor incorporated into the backbone of substituted 4‐hydroxy benzoic acids had a detrimental effect on the liquid‐crystalline behavior. Mesophase‐transition temperatures were observed between 210 and 250°C, and the optical textures were of typical nematic phases. The degree of crystallinity decreased with an increase in the HPOA content. The thermal stability of the copolymers was in the range of 310–370°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008 相似文献
4.
Hiroyuki Sumi Akio Takemura Mikio Kajiyama Yasunori Hatano Bunichiro Tomita Hiroshi Mizumachi 《The Journal of Adhesion》1992,38(3):173-184
Power feed copolymers were synthesized using styrene and n-butyl acrylate through non-uniform feeding emulsion polymerization. Poly(vinyl alcohol) (PVA) was used as a protective colloid, onto which vinyl monomers were grafted. Power feed copolymer had a very broad glass transition temperature compared with random copolymer, even if grafting and/or crosslinking were introduced to the system. This tendency was almost the same as the non-grafted power feed copolymer where only low molecular weight surfactant was used.
Adhesive joint strengths of power feed copolymers were evaluated compared with random copolymers. In the case of usual linear power feed copolymer, the adhesive joint strengths were not higher than those of random copolymer, which was considered to be due to the lower film strengths of the power feed copolymer. Power feed copolymer having grafting showed slightly higher adhesive joint strengths over a wide range of temperatures than random copolymer. When crosslinking was introduced to the system, power feed copolymer showed much higher adhesive joint strengths over a wide temperature range. 相似文献
Adhesive joint strengths of power feed copolymers were evaluated compared with random copolymers. In the case of usual linear power feed copolymer, the adhesive joint strengths were not higher than those of random copolymer, which was considered to be due to the lower film strengths of the power feed copolymer. Power feed copolymer having grafting showed slightly higher adhesive joint strengths over a wide range of temperatures than random copolymer. When crosslinking was introduced to the system, power feed copolymer showed much higher adhesive joint strengths over a wide temperature range. 相似文献
5.
Shiro Torizuka Kaoru Sato Hiroaki Nishio Teruo Kishi 《Journal of the American Ceramic Society》1995,78(6):1606-1610
Compacts of TiB2 with densities approaching 100% are difficult to obtain using pressureless sintering. The addition of SiC was very effective in improving the sinterability of TiB2 . The oxygen content of the raw TiB2 powder used in this research was 1.5 wt%. X-ray photoelectron spectroscopy showed that the powder surface consisted mainly of TiO2 and B2 O3 . Using vacuum sintering at 1700°C under 13–0.013 Pa, TiB2 samples containing 2.5 wt% SiC achieved 96% of their theoretical density, and a density of 99% was achieved by HIPing. TEM observations revealed that SiC reacts to form an amorphous phase. TEM-EELS analysis indicated that the amorphous phase includes Si, O, and Ti, and X-ray diffraction showed the reaction to be TiO2 + SiC → SiO2 + TiC. Therefore, the improved sinterability of TiB2 resulted from the SiO2 liquid phase that was formed during sintering when the raw TiB2 powder had 1.5 wt% oxygen. 相似文献
6.
The rate of evaporation of monodisperse water droplets was first evaluated by solving numerically the modified Maxwell equation, assuming the cellular model for a droplet clouds. The results are discussed in comparison with those for a single isolated droplet, which can be obtained analytically. The critical conditions for the droplet cloud to be stable are then evaluated as a function of droplet number concentration, droplet size and initial conditions of the surrounding air. Secondly, the equilibrated system, where a water droplet cloud is steadily mixed with unsaturated air, was analysed on the basis of enthalpy and material balance of the system to evaluate the total volume change of the droplets. Some of these analyses were verified by experiment, using an ultramicroscopic technique which is useful for droplet size analysis. 相似文献
7.
Thermal behaviors of a few kinds of poly(fluoroalkyl methacrylate) prepared by γ-or UV-ray polymerization were investigated by using thermogravimetric measurements with the intermittent analysis of the gaseous products. The degradation of fluoroalkyl methacrylate polymers, monomeric units of which were CH2=C(CH3)COOCH2(CF2CF2)nH, n = 1, 2, and 3, proceeded according to the depolymerization mechanism reproducing the pristine monomer exclusively, but the thermogram in inert atmosphere showed the features of a two-step reaction. Two species of polymer differing in the heat stability were supposed to exist in the polymeric substance produced by γ- or UV-ray irradiation, and the fraction of polymer having lower heat stability increased with the increasing length of the fluoroalkyl ester group. In air, however, the thermogram of poly(fluoroalkyl methacrylate) showed no such a stepwise weight decrease as was observed in inert atomsphere with the elevating temperature, and the temperatures at which the depolymerization was introduced shifted to a much higher region. The results were ascribed to the reaction of initiating polymer radicals produced on polymer having lower stability with oxygen to form hydroperoxide, which once stabilized the polymer radicals and obstructed the initiaition of the unzipping reaction till higher temperature. 相似文献
8.
Thermal behaviors of a few kinds of poly(fluoroalkyl methacrylate-co-methyl methacrylate) prepared by γ-ray copolymerization were investigated by using thermogravimetric measurements together with the intermittent analysis of the gaseous products. The thermal degradation of copolymers composed of one of fluoroalkyl methacrylates of the following structures: CH2?C(CH3)COOCH2(CF2CF2)nH, where n = 1,2, and 3, and methyl methacrylate proceeded according to the depolymerization mechanism reproducing the pristine component comonomers exclusively, but their thermograms in inert atmosphere showed the feature of a two-step reaction. In air, however, thermograms of copolymers did not show such a stepwise decrease in weight with the elevating temperature, and temperatures at which depolymerization was introduced shifted to a much higher region. The overall aspects of depolymerization of copolymers seemed to be much similar to that of fluoroalkyl methacrylate homopolymer previously reported, and the retardation of depolymerization by air was considered to be due mainly to the stabilization of once-formed polymer radicals by oxygen. 相似文献
9.
10.
Xiao Liu Kaoru Ota Anfeng Liu Zhigang Chen 《Peer-to-Peer Networking and Applications》2016,9(4):692-711
Crowd sensing networks can be used for large scale sensing of the physical world or other information service by leveraging the available sensors on the phones. The collector hopes to collect as much as sensed data at relatively low cost. However, the sensing participants want to earn much money at low cost. This paper examines the evolutionary process among participants sensing networks and proposes an evolutionary game model to depict collaborative game phenomenon in the crowd sensing networks based on the principles of game theory in economics. A effectively incentive mechanism is established through corrected the penalty function of the game model accordance with the cooperation rates of the participant, and corrected the game times in accordance with it’s payoff. The collector controls the process of game by adjusting the price function. We find that the proposed incentive game based evolutionary model can help decision makers simulate evolutionary process under various scenarios. The crowd sensing networks structure significantly influence cooperation ratio and the total number of participant involved in the game, and the distribution of population with different game strategy. Through evolutionary game model, the manager can select an optimal price to facilitate the system reach equilibrium state quickly, and get the number of participants involved in the game. The incentive game based evolutionary model in crowd sensing networks provides valuable decision-making support to managers. 相似文献