Chemoselective hydrogenation of nitro compounds with supported gold catalysts

The selective reduction of a nitro group when other reducible functions are present is a difficult process that often requires stoichiometric amounts of reducing agents or, if H2 is used, the addition of soluble metals. Gold nanoparticles supported on TiO2 or Fe2O3 catalyzed the chemoselective hydrogenation of functionalized nitroarenes with H2 under mild reaction conditions that avoided the accumulation of hydroxylamines and their potential exothermic decomposition. These chemoselective hydrogenation gold catalysts also provide a previously unknown route for the synthesis of the industrially relevant cyclohexanone oxime from 1-nitro-1-cyclohexene.     

Immobilized enzymes and cells as practical catalysts

Performance of enzymes and whole cells in commercial applications can often be dramatically improved by immobilization of the biocatalysts, for instance, by their covalent attachment to or adsorption on solid supports, entrapment in polymeric gels, encapsulation, and cross-linking. The effect of immobilization on enzymatic properties and stability of biocatalysts is considered. Applications of immobilized enzymes and cells in the chemical, pharmaceutical, and food industries, in clinical and chemical analyses, and in medicine, as well as probable future trends in enzyme technology are discussed.     

Scanning tunneling microscopy of galena (100) surface oxidation and sorption of aqueous gold

Scanning tunneling microscopy was used to characterize the growth of oxidized areas on galena (100) surfaces and the formation of gold islands by the reductive adsorption of AuCl(4)(-) from aqueous solution. The gold islands and galena substrate were distinguished by atomic resolution imaging and tunneling spectroscopy. Oxidized areas on galena have [110]-trending boundaries; gold islands elongate along [110] directions. However, there are no obvious structural registry considerations that would lead to elongation of gold islands in a [110] direction. Instead, it is probable that a direct coupling of gold reduction and sulfide surface oxidation controls the initial formation of gold islands. Gold islands grow less quickly on preoxidized galena surfaces and show no preferred direction of growth.     

采用石墨-无机硅胶复合阳极的土壤MFC产电性能研究

土壤微生物燃料电池（MFC）可以将土壤产电细菌分解有机质产生的化学能转化为电能。为了提高土壤MFC的产电性能,实现持续稳定驱动小功率用电器,本研究发明一种新型复合材料作为阳极,在水稻土中构建了土壤MFC。通过串联两个土壤MFC,将输出电压维持在1 403.3~1 579.9 mV,实现持续驱动电子计时器稳定运行30 d。之后移除电子计时器进行土壤MFCs的电化学测试。功率密度曲线显示串联土壤MFCs最大功率密度5.45 mW·m^-2,最大输出功率158.42 μW。电化学阻抗谱分析表明,单个土壤MFC阳极电荷传递电阻分别为16.46 Ω和16.80 Ω。从阳极表面的土壤样品中提取RNA,对逆转录后的16S rRNA进行测序分析。结果显示,土壤MFCs中,阳极上有14个产电细菌相关属,其中地杆菌属（Geobacter）、芽孢杆菌属（Bacillus）、梭菌属（Clostridium）、假单胞菌属（Pseudomonas）和脱硫球茎菌属（Desulfobulbus）16S rRNA的数量均占所有产电细菌相关属总数的10%以上,为最活跃的产电细菌相关属。     

微生物燃料电池处理畜禽养殖废水研究进展及展望

随着畜禽养殖业向规模化、集约化方向发展,畜禽养殖过程中产生的大量废水成为畜禽养殖场周围环境污染的重要因素。微生物燃料电池（Microbial Fuel Cell,MFC）作为一种电化学微生物技术,能够在去除废水中有机物的同时产生电能,在处理高浓度畜禽养殖废水方面具有广阔的发展和应用前景。本文介绍了MFC的分类,并从污染物（化学需氧量、氨氮、总磷和抗生素）去除和产电性能两个方面分析MFC在畜禽养殖废水处理领域的研究现状,并拓展性地阐述了新型耦合MFC技术处理畜禽养殖废水的应用前景,最后指出MFC处理畜禽养殖废水存在的问题,并提出未来可行的发展方向,包括放大装置尺寸、开发新型耦合MFC技术、研究参数的交互作用、深入发掘污染物去除机理和电子传递机制。     

Enhanced ethylene and ethane production with free-radical cracking catalysts

A series of free-radical catalysts have been discovered that increase the yield of highly valuable olefins from the cracking of low molecular weight paraffins. For example, catalytic cracking of n-butane, isobutane, and propane over manganese or iron supported on magnesium oxide (MgO) gave product distributions different from those given by thermal (free-radical) cracking or cracking over traditional acid catalysts. With n-butane and propane feeds, the products from catalytic cracking included large amounts of ethylene and ethane; with isobutane feed, propylene was the major product. Physical characterization of the MgO-supported catalyst showed the manganese to be in a 2+ oxidation state in the reduced catalyst and a 4+ oxidation state in the fully oxidized catalyst. Manganese was also shown to be uniformly distributed in the support material with very little enrichment at the surface. Matrix isolation of the gasphase radicals from n-butane feed showed that ethyl and methyl radicals were produced over the active catalysts. In the thermal process, only methyl radicals were produced. The mechanism of the catalytic reaction appears to be selective formation of primary carbanions at the catalyst surface followed by electron transfer and release of primary hydrocarbon radicals to the gas phase.     

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．     

Anodic oxidation and molecular structure: influence on performance of normal saturated hydrocarbons in fuel cells

Variation in the rate of anodic oxidation of normal saturated hydro carbons (at current densities of half the maximum value or higher) with the carbon number parallels the variation in the rate of diffusion (in electrochemical equivalents) of the hydrocarbon through the electrolyte. This parallelism, not previously recognized, is consistent with the concept of diffusion-influenced anode eactions. The conditions under which this behavior is expected are presented.     

CO2处理种子灭菌防病的方法及应用

农作物病害中有不少重要病害,经种子传带病原物而酿成灾害。介绍利用CO2的窒息灭菌作用,处理农作物染病种子,消灭种子带菌,防治种传病害的方法。     

乌龙茶水提取物对人大肠癌LOVO细胞增殖及凋亡的影响

以赛珍珠5800铁观音为材料,测定乌龙茶中水浸出物、茶多酚、游离氨基酸、可溶性糖、黄酮类物质、没食子酸、8种儿茶素和3种生物碱的含量;并将0、0.2、0.4、0.6、0.8和1.0 mg·m L~(-1)乌龙茶水提取物作用于体外培养的人大肠癌LOVO细胞中,分别处理24和48 h后,采用四甲基偶氮唑蓝(MTT)法测定细胞增殖抑制率,并在倒置显微镜下观察细胞形态的变化;以0.6和0.8 mg·m L~(-1)乌龙茶水提取物处理LOVO细胞48 h,采用流式细胞仪检测细胞凋亡率,扫描电镜下观察细胞凋亡情况.结果表明,乌龙茶中各化学成分的含量均较高,水浸出物含量达40.8%以上,茶多酚含量14.2%,游离氨基酸含量1.8%,可溶性糖含量6.9%,黄酮类物质含量0.7%,儿茶素总量12.2%,咖啡碱含量1.7%,这些成分为其品质保证和功效发挥奠定了一定的物质基础.MTT法试验结果表明:0.2 mg·m L~(-1)乌龙茶水提取物对LOVO细胞生长无抑制作用;处理24和48 h后,0.4~1.0 mg·m L~(-1)乌龙茶水提取物对LOVO细胞生长的抑制率分别达13.9%~79.6%和16.4%~89.2%.0.6和0.8mg·m L~(-1)乌龙茶水提取物处理下LOVO细胞凋亡率分别为60.4%和62.3%,且低含量下细胞凋亡主要呈早期凋亡形式.扫描电镜观察显示,0.6和0.8 mg·m L~(-1)乌龙茶水提取物处理48 h后LOVO细胞出现明显的凋亡现象,细胞体积缩小,细胞间隙增大,表面微绒毛断裂、减少甚至消失,细胞膜表面出现塌陷,产生类似空洞的结构等.因此,乌龙茶水提取物能有效抑制人大肠癌LOVO细胞增殖,并可诱导其凋亡的发生.     

设施环境中进行CO2施肥的气源和方法

提出了设施环境中进行CO2施肥的主要气源；结合设施环境中CO2浓度的日变化特点，阐述了不同季节对常见栽培蔬菜进行C2z施肥的方法和注意事项。     

Regeneration of ammonia borane spent fuel by direct reaction with hydrazine and liquid ammonia

Ammonia borane (H(3)N-BH(3), AB) is a lightweight material containing a high density of hydrogen (H(2)) that can be readily liberated for use in fuel cell-powered applications. However, in the absence of a straightforward, efficient method for regenerating AB from dehydrogenated polymeric spent fuel, its full potential as a viable H(2) storage material will not be realized. We demonstrate that the spent fuel type derived from the removal of greater than two equivalents of H(2) per molecule of AB (i.e., polyborazylene, PB) can be converted back to AB nearly quantitatively by 24-hour treatment with hydrazine (N(2)H(4)) in liquid ammonia (NH(3)) at 40°C in a sealed pressure vessel.     

CO2冷阱微波真空干燥装置设计与试验

为优化微波真空冷冻干燥工艺,基于微波真空冷冻干燥原理研制了CO2冷阱微波真空干燥装置,并介绍了该装置的主要结构、工作原理和工作流程.创新采用液态CO2作为制冷媒,通过合理布局实现CO2的循环利用.采用喷淋冷冻技术,从液态CO2喷淋预冷冻原理出发,设计了喷淋装置结构,并匹配计算了转盘转速,旨在提高物料预冷冻效果.设计了翅...     

金纳米颗粒和多壁碳纳米管协同增敏的维生素C传感器的研制与应用

目的 开发一种低成本、高响应的维生素C电化学传感器,用于实现果蔬中维生素C含量的快速检测。方法 通过在铅笔芯电极上修饰金纳米颗粒和多壁碳纳米管,构建具有维生素C强催化响应的MWCNTs/Au/PGE电极。通过扫描电镜、X射线光电子能谱、拉曼光谱和循环伏安法表征电极,采用差分脉冲伏安法确定电极的pH适用范围和最优pH条件。采用时间电流法建立标准曲线和方程,以实现快速检测。最后通过加标回收率法检测番茄中维生素C含量。结果 基于MWCNTs/Au/PGE电极的维生素C电化学传感器可在pH 4~8范围内准确地测定维生素C含量,在pH 5时性能最优。快速检测时检测维生素C的质量分数范围为1~500 μg/g,灵敏度达0.244 μA·(μg/g)^?1·cm^?2。该传感器对葡萄糖、苹果酸和柠檬酸的干扰率均小于1.77%,同一传感器多次测定的相对标准偏差为2.7%。成功检出番茄样品中的维生素C质量分数为69.42 μg/g,加标回收率为109%~113%,相对标准偏差小于2.26%。结论 MWCNTs/Au/PGE电极制备工艺简单,成本低,灵敏度高,测量范围宽,有较强的稳定性和抗干扰性,为实现快速检测果蔬中维生素C提供了新思路。     

Development and identification of glyphosate-tolerant transgenic soybean via direct selection with glyphosate

Glyphosate-tolerant soybean is the most widely planted genetically modified crop worldwide. However, soybean remains recalcitrant to routine transformation because of the low infection efficiency of Agrobacterium to soybean and lack of useful selectable markers. In this study, several Agrobacterium strains and cell densities were compared by transient expression of the GUS gene. The results showed that Agrobacterium strain Ag10 at cell densities of OD_(600) of 0.6–0.9 yielded the highest infection efficiency in Agrobacterium-mediated soybean cotyledonary node transformation system. Meanwhile, a simple and rapid method was developed for identification of glyphosate tolerance in putative T_0 transgenic plants, consisting of spotting plantlets with 1 μL Roundup~?. The whole cycle of genetic transformation could be shortened to about 3 mon by highly efficient selection with glyphosate during the transformation process and application of the spot assay in putative T_0 transgenic plantlets. The transformation frequency ranged from 2.9 to 5.6%. This study provides an improved protocol for development and identification of glyphosate-tolerant transgenic soybeans.     

水相凝胶色谱法测定草炭土溶解态有机质的分子质量及分子质量分布

以水为流动相,宽分布葡聚糖为标准,用水相凝胶色谱法测定土壤溶解态有机质的分子质量及分子质量分布.样品的进样量、流动相流速对测定结果无明显影响,测定结果的相对标准偏差小于10%.     

对二甲氨基苯甲醛显色分光光度法检测水溶液中常微量尿素

对二甲氨基苯甲醛能够在酸性条件下和尿素反应生成柠檬黄色物质,可依此用比色法测定尿素含量.文章通过条件实验和精密度准确度实验,建立了利用对二甲氨基笨甲醛显色分光光度法检测水溶液中常微量尿素的标准曲线和具体测试方法.选择测试波长为422 nm,对二甲氨基苯甲醛(PDAB)显色剂用量10 mL,硫酸溶液用量4 mL,显色时间...     

CO2超临界萃取法提取苦瓜籽油及其GC-MS分析

一种野生品种苦瓜的籽用索氏提取法提取苦瓜油,测得含油率为38.0％;苦瓜籽仁粉末在CO2超临界状态下,通过正交试验法对萃取压力、温度、时间和CO2流量等因素进行筛选,确定苦瓜籽油萃取工艺参数为萃取压力37 MPa、萃取温度40℃、CO2流量40 L/h、萃取时间为2h时苦瓜籽油得率为97.2％;超临界状态下萃取的苦瓜籽油经GC-MS分析结果表明,苦瓜籽油多种不饱和脂肪酸含量达79.60％,高含量多不饱和脂肪酸的存在使其具有生物活性产品的开发价值.