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排序方式: 共有73条查询结果,搜索用时 15 毫秒
1.
Chumphol Yunphuttha Win Bunjongpru Supanit Porntheeraphat Atchana Wongchaisuwat Charndet Hruanun Amporn Poyai Pinsuda Viravathana 《Chemical Papers》2012,66(12):1137-1145
A direct-methanol fuel cell containing three parts: microchannels, electrodes, and a proton exchange membrane (PEM), was investigated. Nafion resin (NR) and polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (PS) were used as PEMs. Preparation of PEMs, including compositing with other polymers and their solubility, was performed and their proton conductivity was measured by a four point probe. The results showed that the 5 % Nafion resin has lower conductivity than the 5 % PS solution. The micro-fuel cell contained two acrylic channels, PEM, and two platinum catalyst electrodes on a silicon wafer. The assembled micro-fuel cells used 2 M methanol at the flow rate of 1.5 mL min?1 in the anode channel and 5 × 10?3 M KMnO4 at the flow rate of 1.5 mL min?1 in the cathode channel. The micro-fuel cell with the electrode distance of 300 ??m provided the power density of 59.16 ??W cm?2 and the current density of 125.60 ??A cm?2 at 0.47 V. 相似文献
2.
Sie-Tiong Ha Teck-Ming Koh Hong-Cheu Lin Guan-Yeow Yeap Yip-Foo Win Siew-Teng Ong 《Liquid crystals》2013,40(9):917-925
Two homologous series of 2-(4-alkanoyloxybenzylidenamino)benzothiazoles and 2-(2-hydroxy-4-alkanoyloxybenzylidenamino)benzothiazoles were synthesised and characterised. Their molecular structures differed wherein the latter comprised a lateral hydroxyl group, unlike the former. Spectroscopic techniques such as FT-IR, 1H & 13C NMR and mass spectrometry together with elemental analysis were employed to elucidate the molecular structures. The transition temperatures and their mesophases were determined by differential scanning calorimetry, optical polarising microscopy and X-ray diffraction techniques. Members with decanoyloxy till hexadecanoloxy chain in the series without the lateral hydroxyl group each exhibited a smectic A phase, while those in the series with the lateral hydroxyl group were non-mesogenic. The mesomorphic properties of the present series were compared with other structurally related series to establish the chemical structure–mesomorphic properties relationship. 相似文献
3.
We propose a stochastic model of transmitting random information at random time. In this model, the signal is observed as a random sampling according to an increasing stable stochastic process. Thus we are given a subordinate stochastic process which is a typical irreversible process. As the characteristic of this phenomea we observe the loss of entropy. 相似文献
4.
Sie-Tiong Ha Teck-Ming Koh Guan-Yeow Yeap Hong-Cheu Lin Siew-Ling Lee Yip-Foo Win 《Phase Transitions》2013,86(3):195-204
A series of new rod-shaped mesomorphic compounds, 6-ethoxy-2-(4-alkanoyloxybenzylidenamino)benzothiazoles, consisting of a 2,6-disubstituted benzothiazole core and a Schiff base central linkage, were synthesized and their structures were ascertained via elemental analysis and spectroscopic techniques. Their mesomorphic properties were studied using differential scanning calorimetry (DSC), polarized optical microscopy (POM) and X-ray diffraction (XRD) analysis. All compounds showed enantiotropic mesomorphism. Whilst the lower members of the series, hexanoyloxy and octanoyloxy derivatives exhibited nematic phase, the higher members (decanoyloxy, dodecanoyloxy, tetradecanoyloxy, hexadecanoyloxy and octadecanoyloxy derivatives) exhibited nematic and smectic C phases. 相似文献
5.
We propose a new attack on Feistel ciphers with a non-surjective round function such as the CAST cipher family and LOKI91. We extend the attack towards block ciphers that use a non-uniformly distributed round function and apply the extended attack to the CAST family. This attack demonstrates that the round function of a Feistel cipher with six to eight rounds needs to be surjective and sufficiently uniform. 相似文献
6.
G. Bartelt H. G. Buge W. Görner T. Win 《Analytical and bioanalytical chemistry》1998,360(3-4):433-434
Chlorine in wood was determined in connection with the development of a reference material (RM) of pentachlorophenol (PCP) in wood. The element was determined by photon activation analysis (PAA) using bremsstrahlung of 19 MeV electrons from an electron linear accelerator. The initial overall Cl content as well as the Cl remaining after extraction with methanol and subsequent extraction with water were determined. Moreover, the PCP fractions in the organic and in the aqueous extracts were analyzed by gas chromatography (GC). The results show that at least three quarters of the overall chlorine is bound in PCP and that PCP can be extracted to a high degree. 相似文献
7.
The present study is concerned with the determination of the optimal shape for a package containing multiple heating elements.
The optimization tool has been developed based on the inverse heat transfer (IHT) approach, incorporating a direct problem
solver, a numerical grid generator, a direct-differentiation sensitivity analyzer, and the conjugate gradient method. Shape
design that leads to a specified outer surface temperature distribution is predicted by the approach. In this study, the effects
of internal heat generation on optimal shapes of the packagings have also been evaluated. Several practical cases with various
imbedded heating elements and thermal conditions are studied. Results show that the approach provides an efficient computer-aided
design scheme for the shape profile determination. 相似文献
8.
9.
U Myint Khin Mg Nyo Thein Thein Win 《Journal of Radioanalytical and Nuclear Chemistry》1995,201(4):263-267
60Co was used as indicator for studies on the separation of cobalt with sodium alginate. Effect of eight experimental parameters (digestion time, digestion temperature, mode of separation, concentration of reagents, pH, order of heating, ammonia, mixing of reagents) on the precipitation and separation of cobalt alginate have been investigated. 相似文献
10.