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排序方式: 共有2135条查询结果,搜索用时 281 毫秒
1.
Guochun Yan Kyle Reeves Dominique Foix Zhujie Li Claudio Cometto Sathiya Mariyappan Mathieu Salanne Jean‐Marie Tarascon 《Liver Transplantation》2019,9(41)
The Na‐ion battery is recognized as a possible alternative to the Li‐ion battery for applications where power and cost override energy density performance. However, the increasing instability of their electrolyte with temperature is still problematic. Thus, a central question remains how to design Na‐based electrolytes. Here, the discovery of a Na‐based electrolyte formulation is reported which enlists four additives (vinylene carbonate, succinonitrile, 1,3‐propane sultone, and sodium difluoro(oxalate)borate) in proper quantities that synergistically combine their positive attributes to enable a stable solid electrolyte interphase at both negative and positive electrodes surface at 55 °C. Moreover, the role of each additive that consists in producing specific NaF coatings, thin elastomers, sulfate‐based deposits, and so on via combined impedance and X‐ray photoelectron spectroscopy is rationalized. It is demonstrated that empirical electrolyte design rules previously established for Li‐ion technology together with theoretical guidance is vital in the quest for better Na‐based electrolytes that can be extended to other chemistries. Overall, this finding, which is implemented to 18 650 cells, widens the route to the rapid development of the Na‐ion technology based on Na3V2(PO4)2F3/C chemistry. 相似文献
2.
Ranganathan Santhanam 《Inorganica chimica acta》2008,361(2):473-478
A novel method of preparation of hexahydroaluminate complexes M3AlH6 (M = Li, Na or K) from the corresponding alkali metal hydride and tetrahydroaluminate has been explored, using dimethyl ether (Me2O) as a solvent at near-ambient temperatures. The results are compared with those obtained using a recently established mechanochemical approach. Characterization of the products by powder X-ray diffraction revealed M3AlH6 to be formed in high yield for M = Li and Na, but not for M = K. The attempted preparation of Li2NaAlH6 and Li2KAlH6 was unsuccessful. 相似文献
3.
PurposeThe main objective of this study was to evaluate the efficacy of tungsten carbide as new lead-free radiation shielding material in nuclear medicine by evaluating the attenuation properties.Materials and methodsThe elemental composition of tungsten carbide was analysed using Field-Emission Scanning Electron Microscopy (FESEM) with energy dispersive X-ray (EDX). The purity of tungsten carbide was 99.9%, APS: 40–50 µm. Three discs of tungsten carbide was fabricated with thickness of 0.1 cm, 0.5 cm and 1.0 cm. Three lead discs with similar thickness were used to compare the attenuation properties with tungsten carbide discs. Energy calibration of gamma spectroscopy was performed by using 123I, 133Ba, 152Eu, and 137Cs. Gamma radiation from these sources were irradiated on both materials at energies ranging from 0.160 MeV to 0.779 MeV. The experimental attenuation coefficients of lead and tungsten carbide were compared with theoretical attenuation coefficients of both materials from NIST database. The half value layer and mean free path of both materials were also evaluated in this study.ResultsThis study found that the peaks obtained from gamma spectroscopy have linear relationship with all energies used in this study. The relative differences between the measured and theoretical mass attenuation coefficients are within 0.19–5.11% for both materials. Tungsten carbide has low half value layer and mean free path compared to lead for all thickness at different energies.ConclusionThis study shows that tungsten carbide has high potential to replace lead as new lead-free radiation shielding material in nuclear medicine. 相似文献
4.
Both thick- and thin-walled sieve tubes in leaf-blade veins of Hordeum vulgare L. exhibit a distinct, electron-opaque inner wall layer after fixation in glutaraldehyde-osmium tetroxide and staining with uranyl acetate and lead citrate. This inner wall layer is thickest at the sieve plates and lateral sieve areas where it is permeated by a labyrinth of tubules formed by the plasmalemma. Along the lateral walls between sieve areas the inner wall layer apparently is penetrated by numerous microvilli-like evaginations of the plasmalemma, giving the cell wall-plasmalemma interface the appearance of a brush border. It is suggested that a similar brush-border-like structure may occur at the cell wall-plasmalemma interface of sieve elements in a wide variety of vascular plants.Abbreviation ER
endoplasmic reticulum 相似文献
5.
A sampler for collection of interstitial water from wetland sediments is described. It differs from other sampling devices because it does not have to be filled with solution to facilitate diffusion, it does not have to be removed from the wetland to collect samples, and it can be used to draw repeated samples over time from identical locations. The device facilitates in situ measurement of a wide range of abiotic parameters such as electrical conductivity, redox potential, and pH in wetland sediments. The device has application in ecological investigations of sediment-borne wildlife diseases, studies of benthic invertebrates, measurement of nutrient exchange, and other aspects of wetland ecology. 相似文献
6.
Summary The occurrence of plasmodesmata in the graft interfaces of two heteroplastic grafts (Impatiens walleriana onImpatiens olivieri andHelianthus annum onVicia faba) has been studied. For both systems two types of intercellular strand are described: 1. Continuous plasmodesmata interconnecting the cells of stock and scion and 2. half plasmodesmata traversing the wall part of one partner cell without connection to the abutting cell. Single strands or branched forms occur in both types of plasmodesma. In the case of half plasmodesmata, branchings with extended median nodules predominate. The distribution of half and continuous plasmodesmata varies with the different areas of a graft interface: in the region of bridging vascular tissues most cell connections are continuous. In areas where cortex or pith-derived callus cells and those of misaligned tissues (cortex/vascular tissue; cortex/pith; pith/vascular tissue) match, discontinuous strands predominate.Branched half plasmodesmata also occur in presumably fused walls between related callus cells; they are typical structures secondarily formed in non-division walls.The results are discussed with regard to compatibility/incompatibility phenomena in heterografts and the development and function of interspecific cell bridges. 相似文献
7.
A simple theoretical model is presented for simulating the self-sustained oscillations of electric potential and pH at an oil/water interface appearing in a two-phase system composed of 2-nitropropane solution containing picrate acid and an aqueous solution of cetyltrimethylammonium bromide. In the present model, a well-known condition necessary for the occurrence of self-sustained oscillations, i.e., the presence of a positive feedback process far from equilibrium, is taken into account in a set of kinetic equations to describe simplified characters of the following two processes: (i) a cooperative formation of ion pair complexes at the interface, and (ii) supply of picrate anions and cetyltrimethylammonium cations to the interface accompanied by release of ion pair complexes to the organic phase. The numerical solutions of the present equations are shown to reproduce fairly well the characteristic properties of the oscillation of electric potential and pH such as wave forms and frequencies. 相似文献
8.
9.
Edward J. B. Beeley P. A. Bennett L. G. I. Poland J. S. 《Biological trace element research》1990,(1):53-61
A microcomputer-controlled irradiation and measurement system and a microprocessor-controlled sample changer have been installed
at the SLOWPOKE-2 Facility at the Royal Military College of Canada (RMC). These systems can provide the gamut of instrumental
neutron activation analysis (INAA) techniques for the analyst. Custom software has been created for system control, data acquisition,
and off-line spectral analysis using programs that incorporate Gaussian peak-fitting methods of analysis. The design and use
of the equipment is discussed, and the performance is illustrated with results obtained from the analysis of marine sediment
and biological reference materials. 相似文献
10.
本文报道分布于昆明地区的黄臀鹎Pycnonotus xanthorrhous在禁食和四季夜间能量物质——脂肪、蛋白质和糖的消耗情况。结果表明,在人为禁食条件下黄臀鹎的存活时间仅19小时,死亡时躯脂降低79%,去脂飞翔肌干重降低46%,肝糖降低96%。在夜间黄臀鹎消耗大量的储存脂肪,并以冬季的消耗量最大。肝糖提供的能量极少。在繁殖期和换羽期,储存的飞翔肌蛋白质在夜间大量分解以提供鸟体的需要。 相似文献