排序方式: 共有110条查询结果,搜索用时 234 毫秒
11.
Roohollah Torabi Kachoosangi Gregory G. Wildgoose Richard G. Compton 《Electroanalysis》2007,19(14):1483-1489
The voltammetric response of graphite or carbon nanotube paste electrodes, which incorporate the room temperature ionic liquid, N‐butyl‐N‐methyl pyrrolidinium bis(trifluoromethylsulfonyl) imide or [C4mpyrr][NTf2], (RTIL‐CNTPE and RTIL‐CPE respectively) as the binder, towards anionic, cationic and neutral redox probes is examined and compared to conventional paste electrodes which use mineral oil as the binder. The RTIL paste electrodes are found to suffer from very large background currents due to capacitive charging. This is exacerbated further when CNTs are combined with RTILs in the paste. The large charging currents obscure any Faradaic processes of interest, especially at low analyte concentrations. By employing steady state voltammetry at a rotating disk electrode made of the RTIL pastes this problem can be overcome. This allows the electroanalytical properties of these interesting electrode substrates, which combine the attractive properties of CNTs with RTILs to be further explored and developed. 相似文献
12.
Susan Torabi Lukas Hammerschmidt Elena Voloshina Beate Paulus 《International journal of quantum chemistry》2014,114(14):943-951
The performance of wavefunction‐based correlation methods in theoretical solid‐state chemistry depends on reliable Hartree–Fock (HF) results for infinitly extended systems. Therefore, we optimized basis sets of valence‐triple‐ζ quality based on HF calculations for the periodic system of group‐12‐metal difluorides. Scalar‐relativistic effects were included in the case of the metal‐ions by applying small‐core pseudopotentials. To assess the quality of the proposed basis sets, the structural parameters, bulk moduli as well as cohesive and lattice energies of the systems were evaluated at the HF and the density functional theory levels. In addition to these two mean‐field approaches and to assess further employment of our basis sets to wavefunction‐based correlation methods we performed periodic local MP2 computations. Finally, the possibilities of pressure induced structural phase transitions occurring in the ZnF2, CdF2, and HgF2 were investigated. © 2014 Wiley Periodicals, Inc. 相似文献
13.
A criterion was proposed to predict brittle fracture in engineering components containing sharp V-shaped notches and subjected
to mixed mode I/II loading. The criterion, called SV-MTS, was developed based on the maximum tangential stress (MTS) criterion
proposed originally for analyzing crack problems. The curves which are obtained from the SV-MTS criterion could be used conveniently
to predict the fracture resistance and also the notch bifurcation angle in sharp V-notched components under pure mode II and
also mixed mode loading. To evaluate the validity of the proposed criterion, a set of fracture tests were conducted on a new
test specimen, called sharp V-notched Brazilian disc (SV-BD), under mixed mode loading conditions. It is shown that the experimental
results obtained from PMMA specimens are in very good agreement with the curves of SV-MTS criterion. 相似文献
14.
Ranking fuzzy numbers is important in decision-making, data analysis, artificial intelligence, economic systems and operations research. In this paper, to overcome the limitations of the existing studies and simplify the computational procedures an approach to ranking fuzzy numbers based on α-cuts is proposed. The approach is illustrated by numerical examples, showing that it overcomes several shortcomings such as the indiscriminative and counterintuitive behavior of existing fuzzy ranking approaches. 相似文献
15.
We study acoustic vortex in media with screw dislocation using the Katanaev–Volovich theory of defects. It is shown that the screw dislocation affects the beam?s orbital angular momentum and changes the acoustic vortex strength. This change is a manifestation of topological Dirac phase and is robust against fluctuations in the system. 相似文献
16.
Roohollah T. Kachoosangi Gregory G. Wildgoose Richard G. Compton 《Electroanalysis》2008,20(23):2495-2500
The utilization of the capsaicin modified carbon nanotube modified basal‐plane pyrolytic graphite electrode or p‐chloranil modified carbon paste electrodes are presented for the determination of pharmaceutical compounds containing amine functionality, such as benzocaine and lidocaine. In detection of benzocaine at a capsaicin modified electrode, the guaiacol functional group is irreversibly electrochemically oxidized to form the o‐quinone derivative which then undergoes nucleophilic attack by the aromatic amine group in benzocaine via a 1,4‐Michael addition mechanism forming a catechol‐amine adduct. The electrochemically initiated formation of the capsaicin‐benzocaine adduct causes a linear decrease in the voltammetric signal corresponding to capsaicin which correlates to the added concentration of benzocaine. 相似文献
17.
The radiation network method has been applied to calculate the net radiation heat transfer between two concentric hemispheres separated by two hemispherical radiation shields with temperature-dependent surface emissivities. Three different materials are chosen for radiation shields: aluminum oxide, silicon carbide, and tungsten. The reduction in heat transfer with shields depends not only on the surface characteristics of the two shields, but also on the locations of the shields. Three illustrative examples are presented to illustrate the effects of temperature dependent emissivities and shield locations on the percentage heat transfer reduction. The analysis can be used to study other cases as warranted. 相似文献
18.
We found that elemental iodine and bromine are converted to trihalide nucleophiles (triiodine and tribromide anion, respectively) in the presence of catalytic amounts of meso-tetraphenylporphyrins (H2TPP). Therefore a highly regioselective method for the synthesis of beta-haloalcohols through direct ring opening of epoxides with elemental iodine and bromine in the presence of H2TPPs as new catalysts is described. At room temperature a series of epoxide derivatives were converted into the corresponding halohydrins resulting from an attack of trihalide species anion atoms at the less substituted carbon atom. This method occurs under neutral and mild conditions with high yields in various aprotic solvents, even when sensitive functional groups are present. 相似文献
19.
Journal of Thermal Analysis and Calorimetry - In this paper, the idea of using the baffles to improve the performance of the coaxial geothermal heat exchanger (CGHE) has been proposed. Thermal and... 相似文献