[en] Li[Li_1/6Ni_1/4Mn_7/12]O_2−xF_x (x = 0, 0.025, 0.05, 0.075, 0.1) as the cathode materials for rechargeable lithium batteries have been synthesized via the co-precipitation method followed by a high-temperature solid-state reaction. Field emission scanning electron microscopy images exhibit that fluorine substitution catalyzes the growth of the primary particles. Although the initial discharge capacity decreases as the fluorine content increasing, the fluorine substituted materials present significant improvement in the cycling performance. Among the synthesized materials, Li[Li_1/6Ni_1/4Mn_7/12]O_1.95F_0.05 exhibits excellent high temperature (50 °C) cycling performance with a capacity retention of 93.7% after 30 cycles while the bare Li[Li_1/6Ni_1/4Mn_7/12]O₂ cathode exhibited only 73.7%

[en] The ZnO-based ceramic films doped with different dopants were prepared by a novel sol-gel process. The phase composition of the films was determined via X-ray diffraction analysis. The influence of the dopants on the residual stress, carrier concentration and the secondary phases was studied by means of Raman spectroscopy. Raman spectra show that the E₂ phonon frequency shifts 3-6 cm^-1 to lower wavenumbers, whereas the A_1(LO) mode shifts 3.2-6.1 cm^-1 to higher wavenumbers when the films were doped with Bi₂O₃, Sb₂O₃, MnO, Cr₂O₃, Y₂O₃ and Al₂O₃, indicating that both the tensile residual stress and the free carrier concentration were increased with doping. The larger stress is considered to originate from the lattice distortion, which was caused by the substitution of the doping ions for Zn²⁺, and the lattice mismatch between the ZnO crystals and the interfacial phases. The secondary phases were affected markedly by both Y₂O₃ and Al₂O₃. The intensity and the position of Raman bands of Zn₇Sb₂O₁₂ and ZnCr₂O₄ phases changed obviously. The films showed remarkable nonlinear voltage-current characteristics, but the nonlinear coefficient of the films decreased evidently as the addition of Y₂O₃ or Al₂O₃

[en] Highlights: • Free-standing activated carbon fibers/rGO composite films are prepared. • Activated carbon fibers can effectively hinder the agglomeration of rGO. • The electrode membrane can be used without any conducting materials and binder. • High areal capacitance can be achieved by adjusting the film layers. - Abstract: Flexible supercapacitors based on paper-like electrodes have attracted significant interest because of the increasing demands in the energy storage, and they are recently claimed to be minimized and portable for meeting practical applications. As promising binder-free electrode materials in the supercapacitors, graphene-based films have been developed for enhancing their performance in energy storage by insetting “spacers” in-between nanosheets to prevent inevitable aggregations. In this study, a facile and versatile strategy is presented for fabricating graphene-based composite films by introducing activated carbonized cotton fibers to regulate the chemical composition, surface area and pore size distribution. The obtained composite films permit to present substantially increased energy storage capability (capacitance of 310 F g"−"1 and 150 F g"−"1 at 0.1 A g"−"1 and 10 A g"−"1 in 6 mol L"−"1 KOH electrolyte, respectively). Furthermore, tunable areal capacitance is realized by altering the stacked film layers without loss of mass specific capacitance. The devices based on composite films with excellent power density (up to 156.5 mW cm"−"2) and energy density (240 μWh cm"−"2) highlight a controllable, mini-sized and high-efficiency stage for energy storage. Such unique strategy suggests great potential in the commercialization of portable electronic devices, which require greater capacitance in a limited area.

[en] Highlights: • Alumina supported hematite is much more active than bare hematite. • This catalyst is also more active and stable than silica supported hematite. •The particle size of hematite on the supported catalyst is obviously reduced. • The adsorption of anionic dye on alumina-supported catalyst is notably enhanced. -- Abstract: Silica supported hematite (Fe₂O₃/silica) that is more active but less stable than the supported hematite for organic photodegradation in aqueous solution has been reported. In this work, we report on alumina supported hematite (Fe₂O₃/alumina) with significantly improved activity and stability. The catalysts were prepared by mixing alumina with a pre-made colloidal iron oxide at various loading (0–100 wt %), followed by sintering at different temperatures (200–900 °C). Solid characterization with X-ray diffraction and N₂ adsorption showed that hematite particles were small in size, and large in surface area, as compared with the unsupported hematite prepared in parallel. The catalyst activity was evaluated with anionic Orange II as a model substrate, and the reaction was carried out in aerated aqueous suspension under light irradiation at wavelengths longer than 320 nm. As the Fe₂O₃ loading on alumina or the catalyst sintering temperature increased, the apparent rate constant of dye degradation increased, and then decreased. The maximum rate of dye degradation was obtained with 25 wt % Fe₂O₃/alumina, sintered at 400 °C. Moreover, five consecutive experiments for dye photodegradation showed that Fe₂O₃/alumina was much more stable than Fe₂O₃/silica, due to alumina that has a positively charged surface and thus facilitates the dissolved iron species back onto iron oxide. The higher activity of Fe₂O₃/alumina than Fe₂O₃/silica and bare hematite is ascribed to the combined effect between the reduced particle size of hematite and the enhanced surface adsorption of dye on the catalyst

[en] By Monte Carlo simulation the rate of penetrability of two different energy γ ray from ¹⁰⁹Cd radiator through crude oil contented water, we can determine the average density and water content. The simulation results indicates the method is feasible. (authors)

[en] Highlights: • Translucent TiO_2 nanotubes were used as substrate for QDSSCs. • CdS_xSe_1_-_x/Mn-CdS QDs were sensitized onto TiO_2 nanotubes by a two-stage strategy. • The photoresponse of CdS_xSe_1_-_x/Mn-CdS/TiO_2 nanotubes could be tuned with S/Se. • Extra CdSe layers can improve the power conversion efficiency to 3.26%. • Electrochemical measurements well evidenced the improved photovoltaic performance. - Abstract: Translucent TiO_2 nanotube (NT) array film has been used as supporter materials for the fabrication of CdS_xSe_1_-_x/Mn-CdS quantum dot sensitized solar cell (QDSSC). The TiO_2 NT array electrodes are sensitized with Mn-CdS and CdS_xSe_1_-_x QDs by employing a two-stage sensitization strategy combining successive ionic layer adsorption and reaction (SILAR) techniques and hydrothermal process. The photoresponse region of CdS_xSe_1_-_x/Mn-CdS/TiO_2 NT electrodes could be controlled by the ratio of S and Se. By systematical investigation the optimal composition of CdS_xSe_1_-_x, a high power conversion efficiency of 2.41% is obtained with CdS_0_._4_7Se_0_._5_3/Mn-CdS/TiO_2 NT QDSSC prepared with feed molar ratio of S:Se = 0:4. After being coated with 3 SILAR cycles of CdSe on the CdS_0_._4_7Se_0_._5_3/Mn-CdS/TiO_2 NT electrode, the power conversion efficiency could be further improved to the highest value of 3.26%. The enhancement of power conversion efficiency is mainly attributed to the significant increase of short-circuit current density (J_s_c) which resulted from the improved light harvesting ability caused by expanded light absorption range and efficient electrons collection caused by mid-gap states created by Mn-CdS. These results are well evidenced with the photovoltaic performance studies (J-V behaviors), incident photon to charge carrier generation efficiency (IPCE), and electrochemical impedance spectroscopy (EIS)

[en] Translucent TiO₂ nanowires/nanotubes (TiO₂ NW/NT) film would be a promising candidate in constructing photoelectrochemical solar cells for its advantages in sensitizer loading, charge separation, electronic transport and light harvesting. In this report, translucent TiO₂ NW/NT film was prepared by a two-step anodization method. The formation mechanisms of nanowires originated from nanotubes were explored. The hydrogen ions generated by electrolysis of water were driven by electric field to form ions flow, which altered the interfacial stress of nanotubes, resulting in vertically or spirally splitting the mouth of nanotubes to form nanowires. The CdS, CdSe and CdS/CdSe quantum dots (QDs) sensitized TiO₂ NW/NT solar cells were constructed. Among them, The TiO₂ NW/NT solar cells co-sensitized with CdS/CdSe QDs showed higher efficiencies than ones sensitized with CdS or CdSe QDs. By varying successive ionic layer adsorption and reaction (SILAR) cycles of CdS/CdSe, it was found that CdS(9)/CdSe(6)/TiO₂ NW/NT device reached to a maximum power conversion efficiency of 2.41%, which was 78.5% higher than that of the CdS(9)/CdSe(6)/TiO₂ NT solar cell. The excellent photoelectrochemical properties of our solar cell suggest that the translucent TiO₂ NW/NT films co-sensitized with CdS and CdSe QDs have potential application in photovoltaic cells

[en] Energy saving in data centers is increasingly important along with the rapidly developing IT industry. This paper proposes an integrated cooling system for data centers which combines a heat pipe cooling cycle and a vapor compression cooling cycle. The operating mode of the system changes with the outdoor temperature. Key problems of the integrated system were solved such as the mix of the refrigerant and lubricant, the match of heat exchange areas and the durability of valves. A thermal equilibrium test was carried out to evaluate the system performance. Thermodynamic analyses based on experimental data show that the PUE (Power Usage Effectiveness) of data centers using the integrated heat pipe system can be 0.3 lower than using the conventional air cooling systems in cold areas like Beijing and Harbin. The energy saving potential of the integrated heat pipe system varies with seasonal and regional climate changes. - Highlights: • The system combines a heat pipe cycle and a vapor compression cycle. • The operating mode of the system changes with the outdoor temperature. • Several key problems in existing integrated systems are solved. • The new system significantly outperforms the conventional system by test results. • The energy saving potential of the system varies with climate changes.

[en] Vibration problem have been existed on multiple safety injection and spray pumps in the safety systems in many nuclear power plants. Firstly, the vibration condition has been introduced, and the vibration characteristics have been summarized. Spectrum analysis has been implemented. The possible factors related to the fault have been investigated. Secondly, based on the vibration characteristics and frequency spectrum characteristics, a vibration mechanics model is set up. The root cause of excessive vibration is resonance in the system that is consisted of equipment and basement, not the soft feet. It has been validated in the test. Finally, the treatment suggestion of stiffness optimization has been proposed. It was advised that the modal analysis of integral equipment and basement system should be carried out in design phase. (authors)

[en] In order to establish the physical model,we combine experimental method and Monte Carlo simulation method to confirm the dimension of HPGe detector's dead layer and cold finger well.Comparing experimental method with MCNP simulation method, the maximal relative error is 7.87%. (authors)