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991.
本论文采用改进的Hummers法制备了氧化石墨烯(GO),并将氧化石墨烯用十二烷基二甲基苄基氯化铵(1227)进行修饰,得到1227非共价改性的氧化石墨烯(GO-1227)。用拉曼光谱、漫反射红外光谱分析、X-射线光电子表面能谱技术表征了其化学结构;用X-射线衍射分析、扫描电子显微镜与透射电子显微镜观察了其剥离情况和微观形貌;分析了它们在不同溶剂中的分散性。结果表明,季铵盐改性后,1227阳离子通过静电作用插入到GO片层之间,使GO片层进一步剥离,且在极性较弱的有机溶剂中的溶解性增加。热失重分析表明,GO-1227的初始分解温度提高了约70℃。将GO-1227与聚甲基丙烯酸甲酯与苯乙烯的嵌段共聚物(PMMA-b-PS)凝胶聚电解质复合,制备了纳米复合凝胶聚合物电解质(NGPE),并用交流阻抗法测试其电性能,发现占聚电解质总质量2‰的GO-1227可以将其离子电导率提高8.6倍。 相似文献
992.
993.
Xin Cui Xinxin Zhang Mu Yang Yanhui Feng Hongyi Gao Wenbo Luo 《Journal of Thermal Analysis and Calorimetry》2013,113(2):693-701
COREX is the primary process in the current smelting reduction method. The process has strict coal quality standards. Combustion processes of coal used in the COREX operating system were analyzed using a synchronous thermogravimetric analyzer combined with a mass spectrometer. The microcosmic structure and macerals were observed by an electronic scanning microscope. The qualitative and quantitative determinations of oxygen functional groups, such as phenolic hydroxyl, carboxyl, carbonyl, and methoxy groups were detected by the Fourier Transform Infrared spectrometer (FT-IR) and through chemical analysis methods. In addition, the evolution of the chemical structure and transformation mechanism of organic oxygen functional groups during COREX coal combustion have been thoroughly investigated. This study proposes a new coal-requirement index system and coal blending method, which will increase the expansion of coal selection and decrease the overall usage of coal during COREX. 相似文献
994.
WANG Wei YUAN XiaQing LIU XuHui GAO Qiang QI HongLan ZHANG ChengXiao 《中国科学:化学(英文版)》2013,56(7):1009-1016
A selective DNA sensing with zeptomole detection level is developed based on coulometric measurement of gold nanoparticle (AuNPs)-mediated electron transfer (ET) across a self-assembled monolayer on the gold electrode. After immobilization of a thiolated hairpin-structured DNA probe, an alkanethiol monolayer was self-assembled on the resultant electrode to block [Fe(CN)6 ]-3-/4in a solution from accessing the electrode. In the presence of DNA target, hybridization between the DNA probe and the DNA target breaks the stem duplex of DNA probe. Consequently, stem moiety at the 3′-end of the DNA probes was removed from the electrode surface and made available for hybridization with the reporter DNA-AuNPs conjugates (reporter DNA-AuNPs). The thiolated reporter DNA matches the stem moiety at the 3′-end of the DNA probe. AuNPs were then enlarged by immersing the electrode in a growth solution containing HAuCl 4 and H2O2 after the reporter DNA-AuNPs bound onto the electrode surface. The enlarged AuNPs on the electrode restored the ET between the electrode and the [Fe(CN)6]3 -/4- , as a result, amplified signals were achieved for DNA target detection using the coulometric measurement of Fe(CN)6 3- electro-reduction by prolonging the electrolysis time. The quantities of ET on the DNA sensor increased with the increase in DNA target concentration through a linear range of 3.0 fM to 1.0 pM when electrolysis time was set to 300 s, and the detection limit was 1.0 fM. Correspondingly, thousands of DNA (zeptomole) copies were detected in 10L samples. Furthermore, the DNA sensor showed excellent differentiation ability for single-base mismatch. 相似文献
995.
C. S. Wang Y. Liu H. He F. X. Gao L. S. Liu S. W. Chang J. H. Guo L. Chang R. X. Li Y. G. Ouyang 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(1):581-586
The electrochemical separation of uranium from cerium in LiCl–KCl eutectic and the electrochemical behavior of Ce(III) were studied. According to the cyclic voltammogram of Ce(III) and the former result of U(III), electrodeposition potential was determined at ?1.65 V (vs Ag/AgCl). The uranium metal was successfully deposited and separated from cerium. The morphology of deposit and cross section of electrode were investigated by SEM, firstly uranium deposit alloys with stainless steel and forms a thin transition layer, and secondly the uranium metal layer grows from the transition layer. The separation factors of uranium/cerium on different recovery ratios were determined through a series of steps. It was found that the content of cerium in the deposit and separation factors declined with increasing the initial concentration of U3+ in molten salts; the separation factors remained stable at around 20 in different uranium recovery ratios. 相似文献
996.
Sheng Xing Guoli Li Xulu Sun Su Ma Guanjun Chen Lushan Wang Peiji Gao 《Applied biochemistry and biotechnology》2013,171(4):832-846
Aspergillus niger is an effective secretor of glycoside hydrolases that facilitate the saprophytic lifestyle of the fungus by degrading plant cell wall polysaccharides. In the present study, a series of dynamic zymography assays were applied to quantify the secreted glycoside hydrolases of A. niger cultured in media containing different carbon sources. Differences in the diversity and concentrations of polysaccharide hydrolysates dynamically regulated the secretion of glycoside hydrolases. The secretion of β-1,4-endoglucanase isozymes was observed to lag at least 24 h behind, rather than coincide with, the secretion of xylanase isozymes. Low concentrations of xylose could induce many endoxylanases (such as Xyn1/XynA, Xyn2, and Xyn3/XynB). High concentrations of xylose could sustain the induction of Xyn2 and Xyn3/XynB but repress Xyn1/XynA (GH10 endoxylanase), which has a broad substrate specificity, and also triggers the low-level secretion of Egl3/EglA, which also has a broad substrate specificity. Mixed polysaccharide hydrolysates sustained the induction of Egl1, whereas the other β-1,4-endoglucanases were sustainably induced by the specific polysaccharide hydrolysates released during the hydrolysis process (such as Egl2 and Egl4). These results indicate that the secretion of glycoside hydrolases may be specifically regulated by the production of polysaccharide hydrolysates released during the process of biomass degradation. 相似文献
997.
采用巯基-过氧化苯甲酰(BPO)氧化还原引发体系,先实现了甲基丙烯酸缩水甘油酯(GMA)在微米级硅胶微粒表面的引发接枝聚合,制得接枝微粒PGMA/SiO2.使接枝大分子PGMA的环氧基团与5-氨基水杨酸(ASA)发生开环反应,将水杨酸基团键合在接枝大分子侧链,制得功能接枝微粒SA-PGMA/SiO2,并对其化学结构与表面电性能进行了表征.考察研究了功能微粒SA-PGMA/SiO2与咖啡因替代物茶碱分子之间的相互作用力.研究表明,微粒SA-PGMA/SiO2与茶碱分子之间存在有强的次价键力(静电和氢键相互作用).在此基础上,采用本课题组建立的新型分子表面印迹技术,以咖啡因替代物茶碱为模板分子,乙二醇二缩水甘油醚(EGDE)为交联剂,对接枝在硅胶表面的功能大分子链SA-PGMA进行了交联印迹,制备了茶碱分子表面印迹材料MIP-SAP/SiO2,深入考察研究了其分子识别特性.实验结果表明,相对于两种对照物甘油茶碱和苦参碱,印迹材料MIP-SAP/SiO2对茶碱分子具有特异的识别选择性与优良的结合亲和性,相对于甘油茶碱,印迹材料对茶碱的识别选择性系数为7.72. 相似文献
998.
以甲基丙烯酸缩水甘油酯(GMA)为单体, 以乙二醇二甲基丙烯酸酯(EGDMA)为交联剂, 采用悬浮聚合法制得交联聚甲基丙烯酸缩水甘油酯(CPGMA)微球, 然后以4-羟基-2,2,6,6-四甲基哌啶氮氧自由基(4-OH-TEMPO)为试剂, 使CPGMA微球表面的环氧基团发生开环反应, 从而制得了TEMPO固载化微球TEMPO/CPGMA, 考察了制备条件对固载化反应的影响, 并采用多种方法对微球TEMPO/CPGMA进行了表征. 将微球TEMPO/CPGMA与CuCl组成共催化体系, 用于分子氧氧化苯甲醇, 考察了反应条件对催化体系性能的影响. 结果表明, 以含环氧基团的聚合物微球CPGMA为载体, 通过开环反应, 可成功地实现TEMPO的固载化, 开环反应属SN2亲核取代反应, 适宜采用溶剂N,N''-二甲基甲酰胺和反应温度85℃. 非均相催化剂TEMPO/CPGMA与助催化剂CuCl构成共催化体系, 在室温、常压O2条件下可高效地将苯甲醇氧化为苯甲醛, 产物选择性和产率分别为100%和90%. 主催化剂TEMPO与助催化剂CuCl适宜的摩尔比为1:1.2; 主催化剂适宜用量为0.90 g. 此外, TEMPO/CPGMA固体催化剂具有良好的循环使用性能. 相似文献
999.
1000.
Current-voltage electrical behavior of in situ microfibrillar carbon black (CB)/poly(ethylene terephthalate) (PET)/polyethylene (PE) (m-CB/PET/PE) composites with various CB concentrations at ambient temperatures was studied under a direct-current electric field. The current-voltage (I-V) curves exhibited nonlinearity beyond a critical value of voltage. The dynamic random resistor network (DRRN) model was adopted to semi-qualitatively explain the nonlinear conduction behavior of m-CB/PET/PE composites. Macroscopic nonlinearity originated from the interfacial interactions between CB/PET micro fibrils and additional conduction channels. Combined with the special conductive networks, an illustration was proposed to interpret the nonlinear I-V characteristics by a field emission or tunneling mechanism between CB particles in the CB/PET microfibers intersections. 相似文献