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991.
Natural graphite, which is used as an anode material in lithium-ion batteries, is thermally treated to improve its cycleability and reduce irreversible reactions with the electrolyte. Natural graphite is treated in air at 550 °C. The weight loss increases when the thermal oxidation time is increased. The BET surface area of the graphite decreases with increasing weight loss. The cycleability and efficiency of the thermally oxidized natural graphite improves significantly. Thermal oxidation decreases the irreversible capacity for side-reactions with the electrolyte on the first cycle. By contrast, it does not change the reversible capacity and rate capability. The improvement in the cycleability after thermal oxidation may be due to the removal of imperfect sites on the graphite. 相似文献
992.
A novel method for the synthesis of transition-metal boride nanopowder has been developed using a mechanochemical reaction between LiBH4, LiH and transition-metal chloride (TiCl3 and VCl3) by high energy ball milling. This method successfully produces TiB2 and VB2 particles dispersed within a soluble LiCl matrix. Subsequent washing with distilled water, ethanol and acetone to remove the LiCl matrix phase yields TiB2 and VB2 nanopowders of 15-60 nm particle size. From the X-ray diffraction patterns and high resolution transmission electron microscopy image, it is found that each particle is polycrystalline consisting of 3-5 nm crystallites. Neither particle nor crystallite size are increased significantly after heating at 680 °C. 相似文献
993.
Jaekyung Yoon Sanghyun Bae Eunjung Shim Hyunku Joo 《Korean Journal of Chemical Engineering》2007,24(6):1031-1036
In this work, Pt- and Ru-deposited, nitrogen-substituted TiO2 were prepared and characterized by the discoloration of MB and H2 evolution. The characteristics were evaluated in terms of methylene blue (MB) discoloration, open circuit voltage (OCV),
photocurrent (I
ph
), and hydrogen production. First, the Pt-deposited TiON revealed comparable activity in MB discoloration, while both TiONs
resulted in somewhat less activity than P25. Second, an external bias was systematically applied to electrodes made of the
prepared samples, resulting in −0.41∼0.51 OCV, −400∼400 μA and noticeable hydrogen evolution above 300 μA in absolute value
when a bias of −1.5∼1.5 V was applied to the working electrode of P25. The electrolyte and light intensity affected the light-responsive
characteristics of the photocatalysts, confirming the relationship between OCV, I
ph
and H2 and that metal deposition slightly inhibited the I
ph
and H2 evolution while Ru-deposited TiON did not degrade MB effectively. 相似文献
994.
995.
Synthesis of functionalized SBA-15 with ordered large pore size and its adsorption properties of BSA 总被引:2,自引:0,他引:2
Thi Phuong Binh Nguyen Jae-Wook Lee Wang Geun Shim Hee Moon 《Microporous and mesoporous materials》2008,110(2-3):560-569
SBA-15, mesoporous material, is a very excellent candidate for drug delivery system because its pore size is easy to control according to synthesis conditions and the presence of swelling agent. In this study, a known swelling agent, 1,3,5-trimethylbenzene (TMB), was used to increase the pore size with increased aging temperature and prolonged aging time. Furthermore, 3-aminopropyltriethoxysilane (APTES) was incorporated on SBA-15 surface via post synthesis method to separate protein effectively. The samples were characterized by X-ray diffraction (XRD), nitrogen adsorption and desorption analyses, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier Transform Infrared (FT-IR). Adsorption capacity increased with temperature at the isoelectric point (pI) of bovine serum albumin (BSA) regardless of the pore size of SBA-15 samples. Release studies were carried out in the range of pH from neutral to basic solution on unmodified and amine-modified samples. In addition, the adsorption mechanism was investigated by employing the pseudo-first order, pseudo-second order, and intraparticle diffusion models. 相似文献
996.
The effect of the molar ratio of diglycidyl ether of 4,4′-biphenyl (DGEBP) to p-phenylene diamine (PDA) on the cure reaction rate was studied by the Kissinger and isoconversional equations. The cure mechanism was studied by FTIR analysis and the liquid crystalline phase structure was analyzed by wide angle X-ray diffraction (WAXD). With an increasing molar ratio of DGEBP/PDA, the preexponential factor was increased by the increasing collision probability between epoxide groups and primary or secondary amine groups in noncataltyic or catalytic modes. The activation energy also increased because of the increasing content of rigid rodlike mesogen and the high crosslink density, which hindered the diffusion of functional groups. The activation energies obtained from the Kissinger equation were in good agreement with average values obtained from the isoconversional equation. The WAXD pattern showed a smectic layer structure with a layer thickness of 15.3 Å and an intermolecular distance of 4.3 Å. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2372–2380, 2001 相似文献
997.
For pt. I see ibid., vol.16, no.3, pp.6-12 (2000). This article is the second in the series of four related to digital signal processing to enhance partial discharge (PD) detection. In the first overview paper, several methods of removing noise from PD measurements were discussed briefly. In this paper, signal acquisition utilizing time-domain sampling, analog-to-digital (A/D) conversion (quantizing and coding), and signal reconstruction in the context of PD detection will be discussed 相似文献
998.
999.
Some alkali and alkali-earth metal hydrides and their complex hydrides have very high hydrogen storage capacities and reversibility. Unfortunately, most of them have decomposition temperatures that are too high. This must be overcome before these hydrides can be considered seriously as practical hydrogen storage materials for on-board applications. In the present study, the CALPHAD approach has been adopted to evaluate thermodynamically the possibility of destabilizing these high temperature binary ionic hydrides and ternary complex hydrides by reacting them with light elements or other hydrides. The MgH2+Si, LiBH4+MgH2, and LiBH4+Al systems are predicted to show a significant decrease in decomposition temperature. On the other hand, the decrease in the decomposition temperatures of the MgH2+Al and NaBH4+Al systems is relatively small. The LiH+Si system also presents a considerable destabilization effect, which is consistent with experiment. 相似文献
1000.
J-C Kwon H-S Park J-Y An K-B Shim Y-H Kim H-S Shin 《Water science and technology》2005,52(10-11):443-451
In this study, a simple dual sludge process was developed for small sewage treatment. It is a hybrid system that consists of upflow multi-layer bioreactor (UMBR) as anaerobic and anoxic reactor with suspended growth microorganisms and post aerobic biofilm reactor with inclined plates. UMBR is a multifunction reactor that acts as primary sedimentation tank, anaerobic reactor, anoxic reactor, and thickener. The sludge blanket in the UMBR is maintained at a constant level by automatic control so that clear water (30 mg-SS/L) can flow into the post aerobic biofilm reactor. It leads to improving performance of the biofilm reactor due to preventing of excess microbial attachment on the media surface and no requirment for a large clarifier caused by low solid loading. The HRT in the UMBR and the aerobic biofilm reactor were about 5.8 h and 6.4 h, respectively. The temperature in the reactor during this study varied from 12.5 degrees C to 28.3 degrees C. The results obtained from this study show that effluent concentrations of TCOD, TBOD, SS, TN, and TP were 29.7 mg/L, 6.0 mg/L, 10.3 mg/L, 12.0 mg/L, and 1.8 mg/L, which corresponded to a removal efficiency of 92.7%, 96.4%, 96.4%, 74.9%, and 76.5%, respectively. The sludge biomass index (SBI) of the excess sludge in the UMBR was about 0.55, which means that the sludge in the UMBR was sufficiently stabilized and may not require further treatment prior to disposal. 相似文献