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11.
Li N Zheng M Lu H Hu Z Shen C Chang X Ji G Cao J Shi Y 《Chemical communications (Cambridge, England)》2012,48(34):4106-4108
Lithium-sulfur batteries have a poor rate performance and low cycle stability due to the shuttling loss of intermediate lithium polysulfides. To address this issue, a carbon-sulfur nanocomposite coated with reduced graphene oxide was designed to confine the polysulfides. 相似文献
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Dr. Jianzhi Zhang Dr. Tuo Li Dr. Zhilai Hong Chenfei Ma Xiaoting Fang Dr. Fengfeng Zheng Wenkai Teng Prof. Dr. Chuanlun Zhang Prof. Dr. Tong Si 《Angewandte Chemie (International ed. in English)》2023,62(4):e202214344
Discovery of the Asgard superphylum of archaea provides new evidence supporting the two-domain model of life: eukaryotes originated from an Asgard-related archaeon that engulfed a bacterial endosymbiont. However, how eukaryotes acquired bacterial-like membrane lipids with a sn-glycerol-3-phosphate (G3P) backbone instead of the archaeal-like sn-glycerol-1-phosphate (G1P) backbone remains unknown. In this study, we reconstituted archaeal lipid production in Saccharomyces cerevisiae by expressing unsaturated archaeol-synthesizing enzymes. Using Golden Gate cloning for pathway assembly, modular gene replacement was performed, revealing the potential biosynthesis of both G1P- and G3P-based unsaturated archaeol by uncultured Asgard archaea. Unexpectedly, hybrid neutral lipids containing both archaeal isoprenoids and eukaryotic fatty acids were observed in recombinant S. cerevisiae. The ability of yeast and archaeal diacylglycerol acyltransferases to synthesize such hybrid lipids was demonstrated. 相似文献
13.
Zhengbo Zhu Dr. Minami Odagi Dr. Chenfei Zhao Dr. Khalil A. Abboud Helmi Ulrika Kirm Jaan Saame Dr. Märt Lõkov Prof. Dr. Ivo Leito Prof. Dr. Daniel Seidel 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(5):2044-2048
Acyclic ketone-derived oxocarbenium ions are involved as intermediates in numerous reactions that provide valuable products, however, they have thus far eluded efforts aimed at asymmetric catalysis. We report that a readily accessible chiral carboxylic acid catalyst exerts control over asymmetric cyclizations of acyclic ketone-derived trisubstituted oxocarbenium ions, thereby providing access to highly enantioenriched dihydropyran products containing a tetrasubstituted stereogenic center. The high acidity of the carboxylic acid catalyst, which exceeds that of the well-known chiral phosphoric acid catalyst TRIP, is largely derived from stabilization of the carboxylate conjugate base through intramolecular anion-binding to a thiourea site. 相似文献
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The distribution of the chemical elements in plants is closely correlated with biological functions. Micro X-ray fluorescence (μXRF) and X-ray absorption near-edge structure (XANES) spectrometry can be used to determine uptake, translocation, and accumulation of the elements in plants. In this research, μXRF and XANES were applied in studying distribution of the elements in the vegetable and cereal seeds during germination and the mobilization. It was found that (a) the distribution of the elements in the seeds was element specific; (b) K and Ca were mainly located in the embryo. Fe and Zn, as well as Mn and Cu, concentrated near the radicle and new developed root. Most of Pb was located in the new developing root; (c) the organic-Pb complexes functioned as the main components of translocation of Pb in the seeds during germination, and the formation of Pb5(PO4)3Cl and Pb3(PO4)2 in seed and plant tissues was the mechanism of tolerance and detoxification to Pb in plants. 相似文献
16.
一种高效率主被动复合成像雷达分光系统设计 总被引:2,自引:1,他引:1
以小型化、高效率为目的,提出了利用全反射原理,采用复合棱镜结构,通过适当选配光学材料,实现在主被动复合成像雷达接收光学系统中对主、被动光束进行高效率分光的方案.根据技术指标要求完成了分光系统的设计,该系统可以对主动成像光波波长850 nm,全视场角3.5°,被动成像光波中心波长9.7 μm,全视场角6.9°的两束光进行高效率的分光,计算结果表明,对主被动光波分光效率的理论值都可以达到98%以上,该方案还兼具结构稳定,工艺简单,易于工程实现的优点.该设计方案,可以在主被动复合成像激光雷达接收系统中实现主被动共用孔径,从而实现系统的小型化. 相似文献
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Xiao‐Jing Wei Irini Abdiaj Carlo Sambiagio Chenfei Li Eli Zysman‐Colman Jesús Alczar Timothy Noël 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(37):13164-13168
A continuous‐flow, visible‐light‐promoted method has been developed to overcome the limitations of iron‐catalyzed Kumada–Corriu cross‐coupling reactions. A variety of strongly electron rich aryl chlorides, previously hardly reactive, could be efficiently coupled with aliphatic Grignard reagents at room temperature in high yields and within a few minutes’ residence time, considerably enhancing the applicability of this iron‐catalyzed reaction. The robustness of this protocol was demonstrated on a multigram scale, thus providing the potential for future pharmaceutical application. 相似文献
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Shen Chenfei Ma Luyao Zheng Mingbo Zhao Bin Qiu Danfeng Pan Lijia Cao Jieming Shi Yi 《Journal of Solid State Electrochemistry》2012,16(5):1999-2004
Graphene-SnS2 nanocomposites were prepared via a solvothermal method with different loading of SnS2. The nanostructure and morphology of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy
(SEM), and transmission electron microscopy (TEM). The XRD patterns revealed that hexagonal SnS2 was obtained. SEM and TEM results indicated that SnS2 particles distributed homogeneously on graphene sheets. The electrochemical properties of the samples as active anode materials
for lithium-ion batteries were examined by constant current charge–discharge cycling. The composite with weight ratio between
graphene and SnS2 of 1:4 had the highest rate capability among all the samples and its reversible capacity after 50 cycles was 351 mAh/g, which
was much higher than that of the pure SnS2 (23 mAh/g). With graphene as conductive matrix, homogeneous distribution of SnS2 nanoparticles can be ensured and volume changes of the nanoparticles during the charge and discharge processes can be accomodated
effectively, which results in good electrochemical performance of the composites. 相似文献
19.
Artemisia annua L. is an annual herb native of Asia, it has been used for many centuries for the treatment of fever and malaria. In this paper, analysis of the volatile oil of Artemisia annua L. was performed by comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC x GC-TOF MS). Three hundred and three components were tentatively identified and terpene compounds are the main components of Artemisia annua L. volatile oil. Artemisinic acid is tentatively qualified. 相似文献
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A model is developed for predicting the resolution of interested component pair and calculating the optimum temperature programming condition in the comprehensive two-dimensional gas chromatography (GC x GC). Based on at least three isothermal runs, retention times and the peak widths at half-height on both dimensions are predicted for any kind of linear temperature-programmed run on the first dimension and isothermal runs on the second dimension. The calculation of the optimum temperature programming condition is based on the prediction of the resolution of "difficult-to-separate components" in a given mixture. The resolution of all the neighboring peaks on the first dimension is obtained by the predicted retention time and peak width on the first dimension, the resolution on the second dimension is calculated only for the adjacent components with un-enough resolution on the first dimension and eluted within a same modulation period on the second dimension. The optimum temperature programming condition is acquired when the resolutions of all components of interest by GC x GC separation meet the analytical requirement and the analysis time is the shortest. The validity of the model has been proven by using it to predict and optimize GC x GC temperature programming condition of an alkylpyridine mixture. 相似文献