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971.
He Xu Ye Wu Shi-xiao Jin Ye Wang Jin Han Xiao-lin Meng Hai-long Yuan 《Journal of Thermal Analysis and Calorimetry》2014,115(3):2463-2470
The antibacterial activities of a kind of novel peptide from Plutella xylostella (pxCECA1) on methicillin-resistant staphylococcus aureus (MRSA) and Escherichia coli (E. coli) growth were investigated by microcalorimetry. The heat flow power–time curves of MRSA and E. coli growth in the presence of pxCECA1 were recorded using the 3114/3115 Thermal Activity Monitor Air Isothermal Calorimeter based on ampoule mode at 37 °C. Some parameters including growth rate constant k, maximum power output P max, total heat output Qt, generation time t g, growth inhibitory ratio I, and half-inhibitory concentration of the drugs IC50 were obtained to elucidate the antibacterial activity of pxCECA1. The results showed that k, P max, and Q t decreased, but I and t g increased or delayed with the increase in pxCECA1 concentration. The IC50 of pxCECA1 on E. coli was 6.122 μg mL?1 and MRSA was 7.809 μg mL?1. It could be concluded that pxCECA1 had stronger inhibitory effect on E. coli than MRSA. In vivo test was simultaneously performed using an E. coli and MRSA infection model to validate the antibacterial activity of pxCECA1. The results revealed that pxCECA1 with broad spectrum antimicrobial activities hopefully represented a class of promising substitute of antimicrobial agents. 相似文献
972.
Meng Li Hong‐Ye Bai Zu‐Lin Da Xu Yan Chao Chen Jin‐Hui Jiang Wei‐Qiang Fan Wei‐Dong Shi 《Crystal Research and Technology》2015,50(3):244-249
CaFe2O4/MgFe2O4 nanowires with heterostructure had been successfully synthesized by electrospinning method. The obtained samples were systematically characterized by scanning electron microscopy (SEM), X‐Ray diffraction (XRD), UV–Vis diffuse reflectance spectra (UV‐Vis DR) and Environment scanning electron microscopy (ESEM). The novel CaFe2O4/MgFe2O4 nanowires exhibit an enhanced photocatalytic activity for degrading of tetracycline (TC) under visible light. Compared with bare CaFe2O4 or MgFe2O4 samples, the prepared CaFe2O4/MgFe2O4 (Ca:Mg:Fe = 3:2:10) composited nanowires show the best photocatalytic performance with a degradation efficiency of 40% after 150 min reaction time. This enhancement is attributed to the heterostructure of CaFe2O4/MgFe2O4 nanowires, which effectively repress the recombination of photo‐generated electrons and holes. Based on heterostructure and energy band positions, the enhancement of mechanism under visible‐light enhances the photocatalytic activity. 相似文献
973.
Yi-Bo Li Wan-Fen Pu Lin Sun Fa-Yang Jin Jiang-Yu Zhao Jin-Zhou Zhao Tao Huang 《Journal of Thermal Analysis and Calorimetry》2014,118(3):1685-1695
This research aimed at the investigation of the effect of formation factors on the light crude oil during the high temperature air injection process. For this purpose, thermogravimetric and Fourier Transform Infrared Spectroscopy techniques were combined to investigate the light crude oil and oil mixed with formation water and sand at 58, 250, and 450 °C, respectively. The results showed that at different temperature range, the mass drop rate presented different trend and the formation water and sand increased the activation energy of the oxidation reaction. The formation sand exhibited the excellent catalytic effect at relative low temperature. The oxygen addition reaction massively was trigged at 250 °C, and the bond scission reaction dominated at 450 °C. With different additives at different temperature range, the type, concentration, and produced timing of the products presented different tendency. 相似文献
974.
Biosynthesis of Streptolidine Involved Two Unexpected Intermediates Produced by a Dihydroxylase and a Cyclase through Unusual Mechanisms
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Dr. Chin‐Yuan Chang Syue‐Yi Lyu Dr. Yu‐Chen Liu Ning‐Shian Hsu Dr. Chih‐Chung Wu Dr. Cheng‐Fong Tang Kuan‐Hung Lin Dr. Jin‐Yuan Ho Dr. Chang‐Jer Wu Dr. Ming‐Daw Tsai Dr. Tsung‐Lin Li 《Angewandte Chemie (International ed. in English)》2014,53(7):1943-1948
Streptothricin‐F (STT‐F), one of the early‐discovered antibiotics, consists of three components, a β‐lysine homopolymer, an aminosugar D ‐gulosamine, and an unusual bicyclic streptolidine. The biosynthesis of streptolidine is a long‐lasting but unresolved puzzle. Herein, a combination of genetic/biochemical/structural approaches was used to unravel this problem. The STT gene cluster was first sequenced from a Streptomyces variant BCRC 12163, wherein two gene products OrfP and OrfR were characterized in vitro to be a dihydroxylase and a cyclase, respectively. Thirteen high‐resolution crystal structures for both enzymes in different reaction intermediate states were snapshotted to help elucidate their catalytic mechanisms. OrfP catalyzes an FeII‐dependent double hydroxylation reaction converting L ‐Arg into (3R,4R)‐(OH)2‐L ‐Arg via (3S)‐OH‐L ‐Arg, while OrfR catalyzes an unusual PLP‐dependent elimination/addition reaction cyclizing (3R,4R)‐(OH)2‐L ‐Arg to the six‐membered (4R)‐OH‐capreomycidine. The biosynthetic mystery finally comes to light as the latter product was incorporation into STT‐F by a feeding experiment. 相似文献
975.
Pumping through Porous Hydrophobic/Oleophilic Materials: An Alternative Technology for Oil Spill Remediation
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Jin Ge Yin‐Dong Ye Hong‐Bin Yao Xi Zhu Xu Wang Liang Wu Jin‐Long Wang Prof. Hang Ding Prof. Ni Yong Prof. Ling‐Hui He Prof. Dr. Shu‐Hong Yu 《Angewandte Chemie (International ed. in English)》2014,53(14):3612-3616
Recently, porous hydrophobic/oleophilic materials (PHOMs) have been shown to be the most promising candidates for cleaning up oil spills; however, due to their limited absorption capacity, a large quantity of PHOMs would be consumed in oil spill remediation, causing serious economic problems. In addition, the complicated and time‐consuming process of oil recovery from these sorbents is also an obstacle to their practical application. To solve the above problems, we apply external pumping on PHOMs to realize the continuous collection of oil spills in situ from the water surface with high speed and efficiency. Based on this novel design, oil/water separation and oil collection can be simultaneously achieved in the remediation of oil spills, and the oil sorption capacity is no longer limited to the volume and weight of the sorption material. This novel external pumping technique may bring PHOMs a step closer to practical application in oil spill remediation. 相似文献
976.
Hexafluoroantimonic Acid Catalysis: Formal [3+2+2] Cycloaddition of Aziridines with Two Alkynes
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Ming‐Bo Zhou Ren‐Jie Song Prof. Dr. Jin‐Heng Li 《Angewandte Chemie (International ed. in English)》2014,53(16):4196-4199
A practical method for the synthesis of azepine derivatives, a typical seven‐membered heterocyclic ring system, was developed and involves the use of hexafluoroantimonic acid to catalyze a formal [3+2+2] cycloaddition of aziridines with two alkynes. This method was applicable to two of the same or different terminal alkynes for the [3+2+2] cycloaddition with unactivated aziridines, and furnished the corresponding azepine derivatives in good yields with good levels of chemo‐ and regioselectivity. The mechanism was also discussed according to the results of the in situ HRMS and 1H NMR analysis. 相似文献
977.
The lanthanum strontium titanate (LST) has to be calcined at significantly high temperature (above 1,300 °C) to obtain its pure perovskite structure when synthesized by conventional solid-state method, which is main reason for reducing active surface area. In this study, A-site deficient (La0.3Sr0.7)0.93TiO3 was synthesized by Pechini method. Although the prepared powders were calcined at 600 °C, the pure perovskite structure can be obtained without any secondary phase such as TiO2. Moreover, the porosity and surface area are 6 times and one order of magnitude higher in the LST powders synthesized by Pechini method than in the powders synthesized by solid-state method. Based on these results, the LST electrode (Pechini) leads to two times lower electrode resistance than the LST electrode (solid-state). Thus, the LST powders synthesized by Pechini can contributes to saving the energy needed for calcination process as well as increasing the porosity and active surface area, enhancing physical and electrochemical properties in SOFC anode. 相似文献
978.
Rhodium(III)‐Catalyzed N‐Nitroso‐Directed CH Addition to Ethyl 2‐Oxoacetate for Cycloaddition/Fragmentation Synthesis of Indazoles
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Dr. Jinsen Chen Pei Chen Chao Song Prof. Dr. Jin Zhu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(44):14245-14249
RhIII‐catalyzed N‐nitroso‐directed C?H addition to ethyl 2‐oxoacetate allows subsequent construction of indazoles, a privileged heterocycle scaffold in synthetic chemistry, through the exploitation of reactivity between the directing group and installed group. The formal [2+2] cycloaddition/fragmentation reaction pathway identified herein, a unique reactivity pattern hitherto elusive for the N‐nitroso group, emphasizes the importance of forward reactivity analysis in the development of useful C?H functionalization‐based synthetic tools. The synthetic utility of the protocol is demonstrated with the synthesis of a tricyclic‐fused ring system. The diversity of covalent linkages available for the nitroso group should enable the extension of the genre of reactivity reported herein to the synthesis of other types of heterocycles. 相似文献
979.
Back Cover: Two‐Dimensional Tetrathiafulvalene Covalent Organic Frameworks: Towards Latticed Conductive Organic Salts (Chem. Eur. J. 45/2014)
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980.
Shan She Shengtai Bian Prof. Dr. Jian Hao Dr. Jiangwei Zhang Jin Zhang Prof. Dr. Yongge Wei 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(51):16987-16994
A series of aliphatic organoimido derivatives of hexamolybdate based on amantadine, namely (nBu4N)2[Mo6O18(?NC10H15)] ( 1 ), (nBu4N)2 {cis‐[Mo6O17(?NC10H15)2]} ( 2 ), (nBu4N)2{trans‐[Mo6O17(?NC10H15)2]} ( 3 ), and (nBu4N)2[Mo6O16(?NC10H15)3] ( 4 ), was synthesized in reasonable yield by dehydration with N,N′‐dicyclohexylcarbodiimide (DCC). They were characterized by IR and UV/Vis spectroscopy, elemental analysis, ESI mass spectrometry, and single‐crystal X‐ray structure analysis. The spectral and structural similarities and differences between monosubstituted, cis‐disubstituted, and trans‐disubstituted organoimido derivatives were elucidated and may provide guidance for related work on organoimido‐functionalized Lindqvist‐type polyoxometalates. In addition, trans‐disubstituted and polysubstituted derivatives containing aliphatic organoimido ligands have not yet been reported, and the crystal structure of the trans isomer may lead us to a deeper understanding of disubstituted derivatives. Furthermore, proliferation and morphology of MCF‐7 cells were studied with compound 1 . The present results show that the DCC‐dehydrating protocol could be an efficient approach to covalently graft bioactive ligands such as amantadine onto POMs and enhance their application in clinical cancer treatment. 相似文献