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排序方式: 共有1434条查询结果,搜索用时 15 毫秒
931.
Huiling Tai Guangzhong Xie Mingjing Zhao 《International journal of environmental analytical chemistry》2013,93(8):539-551
TiO2/polypyrrole (PPy) nanocomposite ultrathin films for NH3 gas detection were fabricated by the in situ self-assembly technique. The films were characterized by UV–Vis absorption, FT–IR spectroscopy, and atomic force microscopy (AFM). The electrical properties of TiO2/PPy ultrathin film NH3 gas sensors, such as sensitivity, selectivity, reproducibility, and stability were investigated at room temperature in air as well as in N2. The results showed that the optimum gas-sensing characteristics of TiO2/PPy ultrathin film were obtained in the presence of 0.1?wt% colloidal TiO2 for 20-min deposition. Compared with pure PPy thin-film sensors, the TiO2/PPy film gas sensor has a shorter response/recovery time. It was also found that both humidity and temperature had an effect on the operation of the TiO2/PPy film gas sensor at low NH3 concentrations. 相似文献
932.
Wen-Jun Li Chao Tai Xue-Xun Gu 《International journal of environmental analytical chemistry》2013,93(2):127-135
Abstract A simple and rapid preconcentration technique, based on collecting trace hexavalent chromium on an organic soluble membrane filter is described. At pH 5.0, chromium(VI), o-chlorophenyl-fluorone (o-Cl-PF) and tetradecylpyridinium chloride (TDPC) form the ternary ion-associate chelate, which can be collected on a 0.2μm nitrocellulose membrane. The filter is dissolved in a small volume of dimethyl sulfoxide (DMSO) acidified with 0.15 mL 3 mol/L sulfuric acid, and the absorbance of the resulting solution is measured at 545 nm wavelength against the reagent blank. The absorbance is proportional to the content of hexavalent chromium in the range of 0.1–1.8μg, in 5 mL solvent. The sensitivity of the ternary complex reaction is very high with molar absorptivity of 1.2 × 105. A detection limit better than 0.3 μg/L can be achieved. The ions normally present in water do not interfere when mixed masking agents are added. The proposed method has been applied to the analysis of water samples from several sources, the recoveries of the hexavalent chromium added to the samples are quantitative, and results found are satisfactory. 相似文献
933.
Guo Feng Chen Li Yan Zhang Hui Ming Jia Bao Hua Chen Ji Tai Li Shu Xiang Wang Guo Yi Bai 《Research on Chemical Intermediates》2013,39(5):2077-2086
2-Substituted benzothiazoles have been synthesized via one-pot reaction from aromatic aldehydes and o-aminothiophenol catalyzed by silica sulfuric acid in absolute methanol at room temperature. The remarkable advantages offered by this method are an environmentally friendly and reusable catalyst, a simple procedure, mild conditions, short reaction times, and good to excellent yields of products. 相似文献
934.
镍氢电池是目前国内外混合动力汽车的首选电池,但随着稀土价格的不断上涨,稀土元素占其成本的比例约由14%逐步提升到55%,开发无镨、钕的高丰度镧铈稀土元素AB5型储氢材料,有助降低混合动力车用镍氢电池负极材料的成本。采用中频感应熔炼配合快淬甩带工艺制备了LaxCe1-x(NiCoMnAl)5(x=0.8,0.6,0.4)合金,并研究了合金A,B侧各元素的比例以及制备工艺对合金储氢性能及电化学性能的影响。结果表明,随着x的降低,合金的储氢量和放电容量逐渐降低。当x=0.6时,合金电极具有较好的综合电化学性能,最大放电容量达到332.81 mAh.g-1,充放电循环寿命达(715 mA.g-1,80%容量保持率,下同)215次。对该合金B侧Mn,Al含量进行优化后,原材料中的Co含量减少,合金的最高电化学容量可达319.01 mAh.g-1。合金在氩气氛保护下进行退火处理后,结晶度和均匀性上升,电化学容量有所降低,但循环稳定性得到明显改善。其中,经950℃/2 h退火处理的LaxCe1-x(NiCoMnAl)5(x=0.8)合金的最大放电容量达328.07 mAh.g-1,充放电循环寿命达364次。 相似文献
935.
以聚合物纤维负载荧光小分子实现对爆炸物的高灵敏度检测是当前研究的热点之一.本文通过静电纺丝制备了系列聚(偏二氟乙烯-co-六氟丙烯)纤维,当该纤维掺入一定浓度的有机荧光小分子,即双(9-芳胺代芴)联四苯乙烯(TPE-2p TPA),具有聚集诱导增强发光特性.本文研究了复合纤维的表面形貌特征和光物理性能,并应用于荧光化学传感器,对以苦味酸为代表的含氮类爆炸性化合物进行了检查.结果表明,该聚合物复合纤维具有超高的荧光检测灵敏度,可以实现对硝基化合物的超灵敏检测,且具有良好的可重复性,对苦味酸溶液检测可重复利用达9次以上,检测极限达到了10-17g/m L,而对其他含氮类化合物如硝基苯、二硝基苯甲酸也表现出一定的检测特性.同时,在结合实验数据的基础上,我们对检测机理进行了探讨.本研究为爆炸性化合物的选择性检测和高灵敏性检测提供了一种便捷的方法,拓展了荧光传感器的学科内涵. 相似文献
936.
Improved conditions for periodate/Schiff's base‐based fluorescent staining of glycoproteins with dansylhydrazine in SDS‐PAGE
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Xuan Zhou Guo‐Ying Hong Bin‐Bin Huang Yuan‐Meng Duan Jia‐Yi Shen Mao‐Wei Ni Wei‐Tao Cong Li‐Tai Jin 《Electrophoresis》2014,35(10):1439-1447
An improved periodate/Schiff's base based fluorescent stain with dansylhydrazine (DH) for glycoproteins in 1D and 2D SDS‐PAGE was described. Down to 4–8 ng of glycoproteins can be selectively detected within 2 h, which is approximately 16‐fold higher than that of original protocol, but similar to that of Pro‐Q Emerald 488 stain (Invitrogen, Carlsbad, USA). Furthermore, subsequent study of deglycosylation, glycoprotein affinity isolation, and LC‐MS/MS analysis were performed to confirm the specificity of the improved method. As a result, improved DH stain may provide a new choice for selective, economic, MS compatible, and convenient visualization of gel‐separated glycoproteins. 相似文献
937.
A novel fluorescence detection system using a chemosensor for phosphoprotein in gel electrophoretic analysis has been developed. The system employed the alizarin red S‐aluminum (III)‐appended complex as a fluorescent staining dye to perform the convenient and selective detection of phosphorylated proteins and total proteins in SDS‐PAGE, respectively. Therefore, a full and selective map of proteins can be achieved in the same process without resorting to other compatible detection methods. As low as 62.5 ng of α‐ (seven or eight phosphates) and β‐casein (five phosphates), 125 ng of ovalbumin (two phosphates), and κ‐casein (one phosphate) can be detected in approximately 135 min, with the linear responses of rigorous quantitation of changes over a 125–4000 ng range. As a result, alizarin red S‐aluminum (III) stain may provide a new choice for selective, economic, and convenient visualization of phosphoproteins. 相似文献
938.
Double Metal Ions Competitively Control the Guest‐Sensing Process: A Facile Approach to Stimuli‐Responsive Supramolecular Gels
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Dr. Qi Lin Bin Sun Qing‐Ping Yang Yong‐Peng Fu Xin Zhu Prof. Tai‐Bao Wei Prof. You‐Ming Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(36):11457-11462
A facile approach to the design of stimuli‐responsive supramolecular gels (SRSGs) termed double‐metal‐ion competitive coordination control is reported. By this means, the fluorescence signals and guest‐selective responsiveness of the SRSGs are controlled by the competitive coordination of two different metal ions with the gelators and the target guest. To demonstrate this approach, a gelator G2 based on multiple self‐assembly driving forces was synthesized. G2 could form Ca2+‐coordinated metallogel CaG with strong aggregation‐induced emission (AIE). Doping of CaG with Cu2+ results in AIE quenching of CaG and formation of Ca2+‐ and Cu2+‐based metallogel CaCuG. CaCuG could fluorescently detect CN? with specific selectivity through the competitive coordination of CN? with the Cu2+ and the coordination of Ca2+ with G2 again. This approach may open up routes to novel stimuli‐responsive supramolecular materials. 相似文献
939.
Direct Observation of Dynamic Mechanical Regulation of DNA Condensation by Environmental Stimuli
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Amy Lee Adam Karcz Ryan Akman Tai Zheng Sara Kwon Szu‐Ting Chou Sarah Sucayan Dr. Lucas J. Tricoli Jason M. Hustedt Dr. Qixin Leng Prof. Jason D. Kahn Prof. A. James Mixson Prof. Joonil Seog 《Angewandte Chemie (International ed. in English)》2014,53(40):10631-10635
Gene delivery is a promising way to treat hereditary diseases and cancer; however, there is little understanding of DNA:carrier complex mechanical properties, which may be critical for the protection and release of nucleic acids. We applied optical tweezers to directly measure single‐molecule mechanical properties of DNA condensed using 19‐mer poly‐L ‐lysine (PLL) or branched histidine–lysine (HK) peptides. Force–extension profiles indicate that both carriers condense DNA actively, showing force plateaus during stretching and relaxation cycles. As the environment such as carrier concentration, pH, and the presence of zinc ions changes, DNA:HK complexes showed dynamically regulated mechanical properties at multiple force levels. The fundamental knowledge from this study can be applied to design a mechanically tailored complex which may enhance transfection efficiency by controlling the stability of the complex temporally and spatially. 相似文献
940.
Control of the Transition between Ni‐C and Ni‐SIa States by the Redox State of the Proximal FeS Cluster in the Catalytic Cycle of [NiFe] Hydrogenase
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Dr. Hulin Tai Dr. Koji Nishikawa Dr. Masayuki Suzuki Prof. Dr. Yoshiki Higuchi Prof. Dr. Shun Hirota 《Angewandte Chemie (International ed. in English)》2014,53(50):13817-13820
[NiFe] hydrogenase catalyzes the reversible cleavage of H2. The electrons produced by the H2 cleavage pass through three Fe–S clusters in [NiFe] hydrogenase to its redox partner. It has been reported that the Ni‐SIa, Ni‐C, and Ni‐R states of [NiFe] hydrogenase are involved in the catalytic cycle, although the mechanism and regulation of the transition between the Ni‐C and Ni‐SIa states remain unrevealed. In this study, the FT‐IR spectra under light irradiation at 138–198 K show that the Ni‐L state of [NiFe] hydrogenase is an intermediate between the transition of the Ni‐C and Ni‐SIa states. The transition of the Ni‐C state to the Ni‐SIa state occurred when the proximal [Fe4S4]p2+/+ cluster was oxidized, but not when it was reduced. These results show that the catalytic cycle of [NiFe] hydrogenase is controlled by the redox state of its [Fe4S4]p2+/+ cluster, which may function as a gate for the electron flow from the NiFe active site to the redox partner. 相似文献