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951.
Hongqiang Qu Caihong Liu Weihong Wu Lingzhi Chen Jianzhong Xu 《Journal of Thermal Analysis and Calorimetry》2014,115(2):1081-1087
Flame-retarded poly(vinyl chloride) (PVC) materials have been prepared by using zinc ferrite (ZnFe2O4 (ZFO)) combined with magnesium hydroxide (Mg(OH)2 (MH)). The effects of these additives on the combustion and thermal degradation of PVC samples were studied using the limiting oxygen index test, the smoke density rating test, thermogravimetric–differential thermogravimetry, and the cone calorimeter test. The results showed that ZFO and MH were good synergists for improving the flame retardancy and smoke-suppressing of PVC/MH/ZFO blends. ZFO can significantly improve the maximum mass loss velocity in the first stage, and reduce the initial decomposition temperature and the decomposition range in the PVC/MH/ZFO blends. The char yield at 700 °C of flame-retarded PVC clearly decreased below theoretical values due to the cationic cracking reactions in the presence of ZFO. Furthermore, the PVC/10MH/10ZFO showed strong flame-retarding synergism since the decreased average heat release rate value. And the PVC/19MH/1ZFO presented a significant smoke-suppressing effect by the least average specific extinction area, peak smoke production rate, and total smoke produce. Moreover, the CO and CO2 production was increased because of a large amount of fragment of char residue in contact air in the presence of ZFO. 相似文献
952.
Li Sun Chunlei Wang Ying Zhou Qiang Zhao Xu Zhang Jieshan Qiu 《Journal of Solid State Electrochemistry》2014,18(1):49-58
Activated nitrogen-doped carbons (ANCs) were prepared by carbonization/activation approach using aminated polyvinyl chloride (PVC) as precursor. ANCs exhibit larger porosities and higher specific surface areas than those of their nitrogen-free counterparts for the same KOH/carbon ratio. The specific surface area of ANC-1 is up to 1,398 m2 g?1 even at a low KOH/carbon ratio of 1:1. Fourier transform infrared spectroscopy investigation of the nitrogen-enriched resin precursor indicates the efficient dehydrochlorination of PVC by ethylenediamine at a low temperature. The nitrogen content and the population of nitrogen functionalities strongly depend on the KOH/carbon ratios and decrease drastically after KOH activation as seen from the elemental and X-ray photoelectron spectroscopy analysis. The surface concentration of N-6 and N-Q almost disappears and the dominant nitrogen groups become N-5 after KOH activation. The highest specific capacitance of ANCs is up to 345 F g?1 at a current density of 50 mA g?1 in 6 M KOH electrolyte. ANCs also exhibit a good capacitive behavior at a high scan rate of 200 mV s?1 and an excellent cyclability with a capacitance retention ratio as high as ~93 % at a current density of 2,000 mA g?1 for 5,000 cycles. 相似文献
953.
Peng Lv Zhong-min Wang Ying Peng Wen-ping Liu Muhammad-Sadeeq Balogun Huai-ying Zhou 《Journal of Solid State Electrochemistry》2014,18(9):2563-2572
The effect of Cu content on structure, hydrogen storage, and electrochemical properties of LaNi4.1-x Co0.6Mn0.3Cu x alloys has been investigated. For sample, A, B, C, and D are used to represent alloys (x?=?0, 0.15, 0.3, and 0.45), respectively. The results indicate that the four alloys are all single-phase alloy with LaNi5 phase of CaCu5 hexagonal structure, the hydrogen storage capacities of the alloy are about 1.49 wt% (A), 1.48 wt% (B), 1.43 wt% (C), and 1.25 wt% (D) at 303 K. With the increase of Cu content (x) from A to D, hydrogen desorption plateau pressure and pressure hysteresis decrease. Alloy electrode A shows better activation property and higher capacity (334.44 mAh/g). The addition of Cu improves the cyclic stability of the alloy electrodes when x?=?0?~?0.45. However, their self-discharge properties and high-rate dischargeability (HRD) decrease with the increase of x. Further, electrochemical kinetics and electrochemical impedance spectroscopy (EIS) analysis show that the reaction of alloy electrode is controlled by charge transfer step, and the adding of Cu benefits the electrode properties in alkaline solution. 相似文献
954.
Rhodium(III)‐Catalyzed ortho Alkenylation of N‐Phenoxyacetamides with N‐Tosylhydrazones or Diazoesters through CH Activation
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Fangdong Hu Ying Xia Fei Ye Zhenxing Liu Prof. Dr. Chen Ma Prof. Dr. Yan Zhang Prof. Dr. Jianbo Wang 《Angewandte Chemie (International ed. in English)》2014,53(5):1364-1367
A coupling reaction of N‐phenoxyacetamides with N‐tosylhydrazones or diazoesters through RhIII‐catalyzed C? H activation is reported. In this reaction, ortho‐alkenyl phenols were obtained in good yields and with excellent regio‐ and stereoselectivity. Rh–carbene migratory insertion is proposed as the key step in the reaction mechanism. 相似文献
955.
Toehold‐initiated Rolling Circle Amplification for Visualizing Individual MicroRNAs In Situ in Single Cells
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Ruijie Deng Dr. Longhua Tang Qianqian Tian Dr. Ying Wang Lei Lin Prof. Dr. Jinghong Li 《Angewandte Chemie (International ed. in English)》2014,53(9):2389-2393
The ability to quantitate and visualize microRNAs (miRNAs) in situ in single cells would greatly facilitate the elucidation of miRNA‐mediated regulatory circuits and their disease associations. A toehold‐initiated strand‐displacement process was used to initiate rolling circle amplification of specific miRNAs, an approach that achieves both stringent recognition and in situ amplification of the target miRNA. This assay, termed toehold‐initiated rolling circle amplification (TIRCA), can be utilized to identify miRNAs at physiological temperature with high specificity and to visualize individual miRNAs in situ in single cells within 3 h. TIRCA is a competitive candidate technique for in situ miRNA imaging and may help us to understand the role of miRNAs in cellular processes and human diseases in more detail. 相似文献
956.
Azobenzene‐Functionalized Metal–Organic Polyhedra for the Optically Responsive Capture and Release of Guest Molecules
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Dr. Jinhee Park Dr. Lin‐Bing Sun Ying‐Pin Chen Zachary Perry Prof. Dr. Hong‐Cai Zhou 《Angewandte Chemie (International ed. in English)》2014,53(23):5842-5846
Stimuli‐responsive metal–organic polyhedra (srMOPs) functionalized with azobenzene showed UV‐irradiation‐induced isomerization from the insoluble trans‐srMOP to the soluble cis‐srMOP, whereas irradiation with blue light reversed this process. Guest molecules were trapped and released upon cis‐to‐trans and trans‐to‐cis isomerization of the srMOPs, respectively. This study provides a new direction in the ever‐diversifying field of MOPs, while laying the groundwork for a new class of optically responsive materials. 相似文献
957.
Clickable Periodic Mesoporous Organosilicas: Synthesis,Click Reactions,and Adsorption of Antibiotics
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Dr. Jinsuo Gao Xueying Zhang Dr. Shutao Xu Prof. Feng Tan Prof. Xinyong Li Prof. Yaobin Zhang Prof. Zhenping Qu Prof. Xie Quan Dr. Jian Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(7):1957-1963
Pharmaceutical antibiotics are not easily removed from water by conventional water‐treatment technologies and have been recognized as new emerging pollutants. Herein, we report the synthesis of clickable azido periodic mesoporous organosilicas (PMOs) and their use as adsorbents for the adsorption of antibiotics. Ethane‐bridged PMOs, functionalized with azido groups at different densities, were synthesized by the co‐condensation of 1,2‐bis(trimethoxysilyl)ethane (BTME) and 3‐azidopropyltrimethoxysilane (AzPTMS), in the presence of nonionic‐surfactant triblock‐copolymer P123, in an acidic medium. Four different alkynes were conjugated to azide‐terminated PMOs by means of an efficient click reaction. The clicked PMOs showed improved adsorption capacity (241 μg g?1) for antibiotics (ciprofloxacin hydrochloride) compared with azido‐functionalized PMOs because of the enhanced π–π stacking interactions. These results indicate that click reactions can introduce multifunctional groups onto PMOs, thus demonstrating the great potential of PMOs for environmental applications. 相似文献
958.
Stereoelectronic Basis for the Kinetic Resolution of N‐Heterocycles with Chiral Acylating Reagents
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Sheng‐Ying Hsieh Benedikt Wanner Dr. Philip Wheeler Prof. Dr. André M. Beauchemin Prof. Dr. Tomislav Rovis Prof. Dr. Jeffrey W. Bode 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(24):7228-7231
The kinetic resolution of N‐heterocycles with chiral acylating agents reveals a previously unrecognized stereoelectronic effect in amine acylation. Combined with a new achiral hydroxamate, this effect makes possible the resolution of various N‐heterocycles by using easily prepared reagents. A transition‐state model to rationalize the stereochemical outcome of this kinetic resolution is also proposed. 相似文献
959.
Copper‐Catalyzed One‐Pot Denitrogenative–Dehydrogenative–Decarboxylative Coupling of β‐Ketoacids with Trifluorodiazoethane: Facile Access to Trifluoromethylated Aldol Products
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Dr. Heng‐Ying Xiong Zhen‐Yan Yang Zhen Chen Jun‐Liang Zeng Dr. Jing Nie Prof. Jun‐An Ma 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(27):8325-8329
A novel copper‐catalyzed one‐pot cross‐coupling of β‐ketoacids with in situ generated trifluorodiazoethane has been developed. This reaction provides a direct and efficient method, in which one C?C bond and one C?O bond were formed in a carbenoid center with concomitant denitrogenation–dehydrogenation–decarboxylation, to afford trifluoromethylated aldol products. In several preliminary experiments, good to high enantioselectivities were also obtained. 相似文献
960.
Solvothermal Transformation of a Calcium Oleate Precursor into Large‐Sized Highly Ordered Arrays of Ultralong Hydroxyapatite Microtubes
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Dr. Bing‐Qiang Lu Prof. Dr. Ying‐Jie Zhu Feng Chen Chao Qi Xin‐Yu Zhao Jing Zhao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(23):7116-7121
Hydroxyapatite (HAP), a well‐known member of the calcium phosphate family, is the major inorganic component of bones and teeth in vertebrates. The highly ordered arrays of HAP structures are of great significance for hard tissue repair and for understanding the formation mechanisms of bones and teeth. However, the synthesis of highly ordered HAP structure arrays remains a great challenge. In this work, inspired by the ordered structure of tooth enamel, we have successfully synthesized three‐dimensional bulk materials with large sizes (millimeter scale) that are made of highly ordered arrays of ultralong HAP microtubes (HOAUHMs) by solvothermal transformation of calcium oleate precursor. The core–shell‐structured oblate sphere consists of a core that is composed of HAP nanorods and a shell that consists of highly ordered HAP microtube arrays. The prepared HOAUHMs are large: 6.0 mm in diameter and up to 1.4 mm in thickness. With increasing solvothermal reaction time, the HOAUHMs grow larger; the microtubes become more uniform and more ordered. This work provides a new synthetic method for synthesizing highly ordered arrays of uniform HAP ultralong microtubes that are promising for biomedical applications. 相似文献