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[en] A chemiluminescent method of vanadium(IV) determination in the concentration range of 10-500 ppb was proposed. The method is based on the catalytic effect of V(IV) in the chemiluminescent oxidation reaction of quinoline hydrazide (QH) in alkaline medium. Presence of fluorescein (FLU) causes the 9-fold increase of the intensity of chemiluminescent emission and enhances the sensitivity of the method. The proposed method is simple and fast, moreover QH, chemiluminescent analytical reagent, is cheap and very easy to obtain in the laboratory. (author). 5 refs, 2 figs, 1 tab
[en] Highlights: • A method for rapid measurement of the positive side reactions in VFB is presented. • The SOC of positive electrolytes can be detected with resolution of 0.002%. • Side reaction ratios at different charge currents, flow rates are obtained. - Abstract: We present an optical detection method for rapid measurement of the positive side reactions in vanadium flow batteries (VFB). By measuring the transmittance of the positive electrolytes in VFB, the states of charge (SOC) of the positive electrolytes can be detected at very high resolution (better than 0.002% in the SOC range from 98% to 100%), due to the nonlinear transmittance spectra caused by the interactions between V(IV) and V(V) ions. The intensity of the positive side reactions of a VFB can be rapidly measured by a few steps, attributing to the fact that the positive side reactions occur only during the high voltage charging process. The ratios of the positive side reactions at different charge currents and different flow rates are obtained while causing no damage to the battery. This optical detection method can rapidly determine the optimal parameters of the VFB system, providing new means for studying the electrochemical reactions in the VFB system and rapid test in industrial production of VFBs.
[en] Highlights: • A simple dynamic model was proposed to predict the VFB performances. • The change of proton concentration and dynamic diffusion of vanadium ions were considered in the model. • The validity of the proposed model was confirmed via the corresponding experiments. • The simulated results show very good agreement with the experimental data. - Abstract: A simple dynamic model, taking into account the change of proton concentration and dynamic diffusion of vanadium ions, is developed to predict the performances of the vanadium flow battery (VFB). The model is verified via the cycle experiment on the single cell battery assembled with Nafion 115 membrane. The simulated voltage of the VFB single cell during a charge-discharge cycle is in agreement with the experimental results. The efficiency and capacity vs. number of cycles evaluated by this model agree quite well with the experimental data as well. Comparing with the model neglecting the proton concentration change and dynamic diffusion of vanadium ions, the presented model can better forecast the performances of the VFB
[en] Lifetimes of 12 VII levels have been measured by using the technique of laser-excited fluorescence from sputtered metal vapour. The uncertainty is between 7-9%. For a determination of the individual transition probabilities the corresponding emission branching ratios have been measured on a high-current hollow-cathode in conjunction with a 1 m Fourier-transform spectrometer. The f-value of 86 VII lines, which cover a spectral range 260-420 nm, have an uncertainty of about 12%. Comparison is made with literature data. (orig.)
[en] The hybrid ion exchanger consisted of PONF-g-GMA anion fibrous exchanger and IRA-96 bead-type anion exchanger was developed by combining different types of layers with hot-melt adhesive. Its ion exchange capacity and the pressure drop with flow rate of water were measured and the adsorption of vanadium (V) ions on the hybrid ion exchanger was evaluated with various process parameters such as pH, initial concentration, and temperature. It was observed that the adsorption kinetics of vanadium (V) ions on the hybrid ion exchanger could be analyzed with pseudo-second-order model.
[en] The dependence of the current generated in silicon bulk is investigated both theoretically and experimentally. It is demonstrated to be compatible with I∝T2e−1.21eV/2kT expected for the generation via a level near the middle of the band gap
[en] The Fe radiation-induced segregation near the V-5Fe alloy surface after irradiation by the V+, Ar+ and He+ 50 keV ions with the dose of (1-37.5) x 1020 ion m-2 at the temperatures of 30-70 deg C is studied through the method of the X-ray photoelectron spectroscopy. The dependence of the segregation degree on the ions dose type, spatial distribution. generation rate and concentration of the radiation-induced point defects in the area, wherein the segregation is observed, is analyzed
[ru]Методом РФЭС исследована радиационно-индуцированная сегрегация Fe вблизи поверхности сплава V-5Fe после облучения 50 кэВ ионами V+, Ar+ и He+ дозой (1-37.5) x 1020 ион м-2 при температурах 30-70 град С. Проанализирована зависимость степени сегрегации от вида и дозы ионов, пространственного распределения, скорости генерации и концентрации радиационно-индуцированных точечных дефектов в области, где наблюдается сегрегация