Rechargeable lithium batteries with aqueous electrolytes

Rechargeable lithium-ion batteries that use an aqueous electrolyte have been developed. Cells with LiMn(2)O(4) and VO(2)(B) as electrodes and 5 M LiNO(3) in water as the electrolyte provide a fundamentally safe and cost-effective technology that can compete with nickelcadmium and lead-acid batteries on the basis of stored energy per unit of weight.     

制备低硫可膨胀石墨的新工艺

用硫酸(98％)、硝酸(65％)和草酸的混合液与天然鳞片石墨反应制备低硫可膨胀石墨。最佳反应条件是：石墨、硫酸(98％)、硝酸(65％)、草酸的重量比为1：2．3：1．7：0．05，反应时间45min，反应温度为25℃，可膨胀石墨的含硫量为1．63％时，膨胀容积为250mL/g，其终端产品柔性石墨的含硫量为780mg/kg。     

硫/珊瑚石填料床的自养反硝化反应器

采用硫/珊瑚石填料床反应器去除人工合成废水中的硝酸盐.结果表明,该反应器通过硫自养反硝化作用能有效去除水体中硝酸盐氮.硫与珊瑚石体积比为1∶1、温度为(29±1)℃时,0.092-0.246 kg.m-3.d-1NO3--N为最适进水负荷,可确保NO3--N的去除率大于95%,且出水NO2--N含量低于1 mg.L-1;进水负荷达0.842 kg.m-3.d-1NO3--N时,达到最大体积去除负荷,为0.394 kg.m-3.d-1NO3--N,而相应出水NO2--N含量达40.95 mg.L-1.在不提高碱度的情况下,出水pH可始终维持在7.08以上.不同硫/珊瑚石体积配比对反硝化效率有显著影响,1∶1体积配比为该反应器最适填料配比.     

固体氧化物燃料电池LSM阴极材料的制备及选择性研究

采用固相法、燃烧法和溶解-凝胶法等3种制备固体氧化物燃料电池阴极材料的常用方法合成了La0.7Sr0.3MnO3（LSM）材料．合成的粉体成,钙钛矿结构,没有杂相生成．采用三电极法对阴极材料的电化学性能进行了研究;同时将制备的3种LSM阴极材料应用于阳极支撑型固体氧化物燃料电池,组装成单电池,采用四电极法对单电池的输出性能进行了测试和比较．结果表明,溶胶-凝胶法合成的LSM阴极材料在800℃下界面电阻最小。约为3Ω·cm^2,表现出良好的电性能．溶胶-凝胶法合成的LSM阴极材料制备的单电池电化学性能优良,在800℃时,输出功率密度达745mW／cm^2．     

A major constituent of brown algae for use in high-capacity Li-ion batteries

The identification of similarities in the material requirements for applications of interest and those of living organisms provides opportunities to use renewable natural resources to develop better materials and design better devices. In our work, we harness this strategy to build high-capacity silicon (Si) nanopowder-based lithium (Li)-ion batteries with improved performance characteristics. Si offers more than one order of magnitude higher capacity than graphite, but it exhibits dramatic volume changes during electrochemical alloying and de-alloying with Li, which typically leads to rapid anode degradation. We show that mixing Si nanopowder with alginate, a natural polysaccharide extracted from brown algae, yields a stable battery anode possessing reversible capacity eight times higher than that of the state-of-the-art graphitic anodes.     

Solid state electrodes for high energy batteries

A new class of electrode materials for high energy density, rechargeable batteries based on topochemical reactions of lithium and transition metal compounds is evolving. The physical and structural properties relevant to the ability of transition metal oxides with framework structures to topochemically incorporate lithium are discussed. Perovskite-related structures are particularly attractive hosts for lithium.     

A sulfur dioxide climate feedback on early Mars

Ancient Mars had liquid water on its surface and a CO2-rich atmosphere. Despite the implication that massive carbonate deposits should have formed, these have not been detected. On the basis of fundamental chemical and physical principles, we propose that climatic conditions enabling the existence of liquid water were maintained by appreciable atmospheric concentrations of volcanically degassed SO2 and H2S. The geochemistry resulting from equilibration of this atmosphere with the hydrological cycle is shown to inhibit the formation of carbonates. We propose an early martian climate feedback involving SO2, much like that maintained by CO2 on Earth.     

A thiosulfate shunt in the sulfur cycle of marine sediments

The oxidation of sulfide, generated by bacterial sulfate reduction, is a key process in the biogeochemistry of marine sediments, yet the pathways and oxidants are poorly known. By the use of (35)S-tracer studies of the S cycle in marine and freshwater sediments, a novel shunt function of thiosulfate (S(2)O(3)(2-)) was identified. The S(2)O(3)(2-) constituted 68 to 78 percent of the immediate HS(-)-oxidation products and was concurrently (i) reduced back to HS(-), (ii) oxidized to SO(4)(2-), and (iii) disproportionated to HS(-) + SO(4)(2-). The small thiosulfate pool is thus involved in a dynamic HS(-) - S(2)O(3)(2-) cycle in anoxic sediments. The disproportionation of thiosulfate may help account for the large difference in isotopic composition ((34)S/(32)S) of sulfate and sulfides in sediments and sedimentary rocks.     

一种新型微量钾离子传感器的研究

[目的]钾的精确测定是临床诊断和营养分析的关键,为了解决钾离子的定量检测问题,[方法]本文采用巯基乙胺修饰丝网印刷金电极表面并绑定4-氨基二苯并-18-冠-6的方法,研制出一种电流型传感器。在电压范围为-0.3~0.6V,阶跃次数为1以及脉冲宽度为200s时进行电流计时测定。[结果]结果表明,180s后传感器电流稳定,而且该电流与1×10~(-5)~1×10~(-4) mol·L~(-1)范围内的钾离子浓度呈良好的线性关系,显著性检验概率p值小于0.000 1,决定系数为0.998 1。[结论]通过电化学循环伏安法对传感器电极制作过程的表征研究表明,该方法不但可显著改善电极的可逆性及导电性,有利于提高传感器的灵敏度,而且有利于微型钾离子传感器的制作。     

A cryptic sulfur cycle in oxygen-minimum-zone waters off the Chilean coast

Nitrogen cycling is normally thought to dominate the biogeochemistry and microbial ecology of oxygen-minimum zones in marine environments. Through a combination of molecular techniques and process rate measurements, we showed that both sulfate reduction and sulfide oxidation contribute to energy flux and elemental cycling in oxygen-free waters off the coast of northern Chile. These processes may have been overlooked because in nature, the sulfide produced by sulfate reduction immediately oxidizes back to sulfate. This cryptic sulfur cycle is linked to anammox and other nitrogen cycling processes, suggesting that it may influence biogeochemical cycling in the global ocean.     

钾细菌K906培养特征及液体深层发酵研究

本文对分离的钾细菌K906的一般固体培养和液体深层发酵特性及配方进行了研究.表明K906菌株在无氮培养基上形成荚膜.在有氮培养基上不形成荚膜.而形成许多短小杆菌和孢子,且生长大大快于无氮培养基.达10倍以上.K906菌株利用可溶性淀粉作碳源.在培养基中加入酵母能大大促进钾细菌的生长;3-4d摇瓶培养高峰菌数达10×108个/ml.1000L发酵罐淀粉氨溶液深层培养8批次.发酵周期40-60h.放罐菌数平均达18,9×108个/n1l.适合工业化生产.     

Electrodes with high power and high capacity for rechargeable lithium batteries

New applications such as hybrid electric vehicles and power backup require rechargeable batteries that combine high energy density with high charge and discharge rate capability. Using ab initio computational modeling, we identified useful strategies to design higher rate battery electrodes and tested them on lithium nickel manganese oxide [Li(Ni(0.5)Mn(0.5))O2], a safe, inexpensive material that has been thought to have poor intrinsic rate capability. By modifying its crystal structure, we obtained unexpectedly high rate-capability, considerably better than lithium cobalt oxide (LiCoO2), the current battery electrode material of choice.     

Interstellar sulfur hydride: a search for the 111-megahertz lines

Similarities in the energy-level structure of the sulfur hydride radical and the hydroxyl radical suggest that sulfur hydride in the interstellar medium might be detectable because of a population inversion or anti-inversion similar to that of the hydroxyl radical. We have searched for the 111.54-megahertz transition [F (total angular momentum quantum number) = 2 --> 2] and for the 111.22-megahertz transition (F = 1 --> 1) in the galactic radio source W49, one of the brightest hydroxyl emission sources. No sulfur hydride emission lines with half-power widths of 130 hertz or greater were detected with the 1000-foot Arecibo antenna. The upper limits established with 100-hertz filters were 50 and 60 flux units (1 flux unit= 10(26) watt meter(-2) hertz(-1)), respectively, for the two lines.     

A low-operating-temperature solid oxide fuel cell in hydrocarbon-Air mixtures

The performance of a single-chamber solid oxide fuel cell was studied using a ceria-based solid electrolyte at temperatures below 773 kelvin. Electromotive forces of approximately 900 millivolts were generated from the cell in a flowing mixture of ethane or propane and air, where the solid electrolyte functioned as a purely ionic conductor. The electrode-reaction resistance was negligibly small in the total internal resistances of the cell. The resulting peak power density reached 403 and 101 milliwatts per square centimeter at 773 and 623 kelvin, respectively.     

A generalized approach to the modification of solid surfaces

Interfacial interactions underpin phenomena ranging from adhesion to surface wetting. Here, we describe a simple, rapid, and robust approach to modifying solid surfaces, based on an ultrathin cross-linkable film of a random copolymer, which does not rely on specific surface chemistries. Specifically, thin films of benzocyclobutene-functionalized random copolymers of styrene and methyl methacrylate were spin coated or transferred, then thermally cross-linked on a wide variety of metal, metal oxide, semiconductor, and polymeric surfaces, producing a coating with a controlled thickness and well-defined surface energy. The process described can be easily implemented and adapted to other systems.     

吸附法去除水环境中邻苯二甲酸酯类污染的研究进展

邻苯二甲酸酯类(Phthalic acid esters,PAEs)是一类应用广泛的增塑剂,主要添加在塑料制品、橡胶、医疗器械和儿童玩具中。PAEs通过废水排放、大气干湿沉降、塑料废弃物渗出等途径进入饮用水、地表水和地下水环境中,由于其具有致畸、致癌和致突变作用,并对鱼类、哺乳类动物具有内分泌干扰效应,因此引起了全世界的广泛关注。本文综述了目前常用的吸附方法去除水环境中PAEs的效果和机理,重点阐述了活性炭、壳聚糖、生物质、黏土矿物、人工树脂、膜材料、纳米材料、分子印迹聚合物等新型材料对PAEs的吸附效果、吸附性能和机理,对这些材料吸附去除PAEs的优缺点做了简单总结,并对吸附法去除PAEs的发展前景进行了展望。     

Continuous random network model for amorphous solid water

Continuous random network models representing amorphous solid water have been constructed. The x-ray and neutron scattering predictions for one type of model agree quite well with experimental results.     

锂离子电池锡镍合金负极材料的性能研究

采用基于密度泛函理论的第一性原理平面波赝势方法计算了Sn-Ni合金中2种稳定相结构的物理性质和电化学性质.结果表明:Ni3Sn2具有相对稳定的电化学电位,Ni3Sn4具有波动性电化学电位.同时运用电化学沉积制备了Sn-Ni合金负极材料,测试结果标明Ni3Sn4具有优异的电化学性能,是适合用作锂离子电池的理想结构材料.     

生物反应器填埋场处理生活垃圾的研究进展

介绍了生物反应器填埋场的结构特点及其对渗滤液和微生物生态的影响,并概述了国内外有关生物反应器填埋场处理生活垃圾研究的主要类型和发展趋势.