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911.
Being a best known thermoelectric material and a topological insulator at ambient condition, magic bismuth telluride (Bi2Te3) under pressure transforms into several superconducting phases, whose structures remain unsolved for decades. Here, we have solved the two long-puzzling low high-pressure phases as seven- and eightfold monoclinic structures, respectively, through particle-swarm optimization technique on crystal structure prediction. Above 14.4 GPa, we experimentally discovered that Bi2Te3 unexpectedly develops into a Bi-Te substitutional alloy by adopting a body-centered cubic disordered structure stable at least up to 52.1 GPa. The continuously monoclinic distortion leads to the ultimate formation of the Bi-Te alloy, which is attributed to the Bi→Te charge transfer under pressure. Our research provides a route to find alloys made of nonmetallic elements for a variety of applications. 相似文献
912.
An efficient diode-pumped Yb:Y3Ga5O12 (Yb:YGG) laser was demonstrated by using a high-quality Yb:YGG crystal grown by the optical floating zone method. Continuous-wave laser power up to 2.65?W had been obtained under an incident pump power of 6.71?W at 970?nm, corresponding to an optical-to-optical efficiency of 39.5% and maximum slope efficiency of 84.5%. A modeling calculation of the Yb:YGG laser was also performed, and the theoretical results were consistent with the experimental results. 相似文献
913.
Jiang J Xu HD Xi JB Ren BY Lv FP Guo X Jiang LQ Zhang ZY Hu WH 《Journal of the American Chemical Society》2011,133(22):8428-8431
The diastereoselectively switchable enantioselective trapping of protic carbamate ammonium ylides with imines is reported. The intriguing Rh(2)(OAc)(4) and chiral Br?nsted acid cocatalyzed three-component Mannich-type reaction of a diazo compound, a carbamate, and an imine provides rapid and efficient access to both syn- and anti-α-substituted α,β-diamino acid derivatives with a high level control of chemo-, diastereo-, and enantioselectivity. 相似文献
914.
Xiaoyan HuGang Lv Zhiyong JiaJian Jiang Ting XiaoMin Yuan Yiwen Tang 《Applied Surface Science》2011,257(21):9008-9013
A general sonochemical approach that allows for a facile, rapid synthesis of MSn(OH)6 (M = Ba, Ca, Sr) one-dimension (1D) nanostructures has been developed. The resulting CaSn(OH)6 products possessed a nanotubular structure while SrSn(OH)6 and BaSn(OH)6 showed nanowire-like structures. The as-synthesized MSn(OH)6 products were characterized by XRD, SEM and TEM techniques. Owing that BaSn(OH)6 nanowires, CaSn(OH)6 nanotubes, and SrSn(OH)6 nanowires takes different crystal structures respectively, they share different growth mechanisms. However, we found that in all three growing processes, both ultrasound irradiation and the presence of Na2CO3 in the synthetic procedure had an significant impact on the homogeneous nucleation and fast growth of 1D MSn(OH)6 nanostructures. This approach represents a successful example for the fast construction of innovative inorganic nanostructures in the absence of any surfactants. 相似文献
915.
Shide Lv Xiaoxin Han Jian‐Yong Wang Mingyang Zhou Yanwei Wu Li Ma Liwei Niu Wei Gao Jianhua Zhou Wei Hu Yuezhi Cui Jianbin Chen 《Angewandte Chemie (International ed. in English)》2020,59(28):11583-11590
Herein, an environmentally friendly electrochemical approach is reported that takes advantage of the captodative effect and delocalization effect to generate nitrogen‐centered radicals (NCRs). By changing the reaction parameters of the electrode material and feedstock solubility, dearomatization enabled a selective dehydrogenative C?N versus N?N bond formation reaction. Hence, pyrido[1,2‐a]benzimidazole and tetraarylhydrazine frameworks were prepared through a sustainable transition‐metal‐ and exogenous oxidant‐free strategy with broad generality. Bioactivity assays demonstrated that pyrido[1,2‐a]benzimidazoles displayed antimicrobial activity and cytotoxicity against human cancer cells. Compound 21 exhibited good photochemical properties with a large Stokes shift (approximately 130 nm) and was successfully applied to subcellular imaging. A preliminary mechanism investigation and density functional theory (DFT) calculations revealed the possible reaction pathway. 相似文献
916.
Jian‐Ming Lv Yao‐Hui Gao Huan Zhao Takayoshi Awakawa Ling Liu Guo‐Dong Chen Xin‐Sheng Yao Dan Hu Ikuro Abe Hao Gao 《Angewandte Chemie (International ed. in English)》2020,59(32):13531-13536
The alkyne is a biologically significant moiety found in many natural products and a versatile functional group widely used in modern chemistry. Recent studies have revealed the biosynthesis of acetylenic bonds in fatty acids and amino acids. However, the molecular basis for the alkynyl moiety in acetylenic prenyl chains occurring in a number of meroterpenoids remains obscure. Here, we identify the biosynthetic gene cluster and characterize the biosynthetic pathway of an acetylenic meroterpenoid biscognienyne B based on heterologous expression, feeding experiments, and in vitro assay. This work shows that the alkyne moiety is constructed by an unprecedented cytochrome P450 enzyme BisI, which shows promiscuous activity towards C5 and C15 prenyl chains. This finding provides an opportunity for discovery of new compounds, featuring acetylenic prenyl chains, through genome mining, and it also expands the enzyme inventory for de novo biosynthesis of alkynes. 相似文献
917.
Chen‐Chen Li Jian Kan Zihang Qiu Jianbin Li Leiyang Lv Chao‐Jun Li 《Angewandte Chemie (International ed. in English)》2020,59(11):4544-4549
Herein, we report a ruthenium‐catalyzed redox‐neutral α‐alkylation of unsaturated alcohols based on a synergistic relay process involving olefin isomerization (chain walking) and umpolung hydrazone addition, which takes advantage of the interaction between the two rather inefficient individual reaction steps to enable an efficient overall process. This transformation shows the compatibility of hydrazone‐type “carbanions” and active protons in a one‐pot reaction, and at the same time achieves the first Grignard‐type nucleophilic addition using olefinic alcohols as latent carbonyl groups, providing a higher yield of the corresponding secondary alcohol than the classical hydrazone addition to aldehydes does. A broad scope of unsaturated alcohols and hydrazones, including some complex structures, can be successfully employed in this reaction, which shows the versatility of this approach and its suitability as an alternative, efficient means for the generation of secondary and tertiary alcohols. 相似文献
918.
Zijie Luo Taoyuze Lv Kangning Zhu Yi Li Lei Wang J. Justin Gooding Guozhen Liu Bin Liu 《Angewandte Chemie (International ed. in English)》2020,59(8):3131-3136
Monitoring of human serum albumin (HSA) in a point‐of‐care fashion is urgently needed in particular for elderly or chronically ill patients. Herein, a dual‐state emissive chalcone probe having the feature of aggregation‐induced emission was designed and synthesized. The concentration of HSA can be evaluated by the ratios of emission from probes in aggregated and monomeric state, which gives a visually discernible red‐to‐green color change. A simple, portable paper‐based analytical device have been fabricated by integration of the recognition probe in the detection pad and employed for HSA test using the whole blood samples. This paper‐based assay shows the analytical capability comparable to the standard testing methods but is in a point‐of‐care fashion, providing a promising tool for at‐home HSA detection and HSA‐related disease diagnosis. 相似文献
919.
Xiao‐Hong Fan Yuan‐Hang Chang Li‐Tao Wang Ya‐Wei Zhu Ming‐Zhu Dong Mu‐Jie Lv Juan‐Yan An Qing Yang Jiao Jiao Dong Meng Yu‐Jie Fu 《Journal of separation science》2020,43(7):1339-1347
Taxanes are natural anticancer constituents, and the sample preparation from matrix normally depends on organochlorine solvents. In this study, green and natural menthol‐based aqueous deep eutectic solvent was synthesized and used for sample preparation for taxanes. Five key parameters were optimized and the optimal preparation conditions were as follows: menthol/1‐propanol ratio 1:1 (mol/mol), solid–liquid ratio 1:30 g/mL, extraction time 30 min, ultrasonic power 250 W, and water content 80%. Under the above conditions, the total extraction efficiency of seven main taxanes was 1.25‐ to 1.44‐fold to the conventional methods. In addition, a high‐performance liquid chromatography method with C18 column was established for quantitation of seven main taxanes in <25 min, which had excellent linearity (R2 > 0.9986), precision (relative standard deviation < 3.00%), repeatability (relative standard deviation < 3.69%), and recovery (90.26–109.00%). This method performed the extraction, and enrichment processes simultaneously, and it had advantages such as high extraction efficiency, simple operation, low cost, and eco‐friendliness. This work indicated that the natural menthol‐based deep eutectic solvent aqueous could be an excellent alternative to the sample preparation from Taxus or other plants. 相似文献
920.
Jiaye Wang Bin Jiang Yingying Shan Xiaoli Wang Xi Lv Jihan Mohamed He Li Chunmei Wang Jianguang Chen Jinghui Sun 《Journal of separation science》2020,43(2):378-388
Schisandra chinensis lignans are the main active components of the traditional Chinese medicine Schisandra chinensis in East Asia. At present, there are more and more medicines and health foods in which the total S. chinensis lignans extracts are considered as the main active components, but little research has been done on the active components of S. chinensis lignans in the blood and main target organs. In this study, the components of S. chinensis lignans in the blood, liver and brain tissues of rats at different time points after the intragastrical administration of S. chinensis lignans were determined by a metabolomic method based on high‐performance liquid chromatography with quadrupole time‐of‐flight tandem mass spectrometry spectrometry. Twelve Schisandra chinensis lignans and 15 metabolites in the blood, liver, and brain of rats were identified. The results showed that the main metabolic ways of S. chinensis lignans in rats were hydroxylation, demethylation, and demethylation‐hydroxylation, and some of them might undergo demethylation, dehydrogenation, epoxidation, and elimination reaction. The time‐dose characteristics of S. chinensis lignans and their metabolites in the blood and target organs were analyzed, which may be helpful to elucidate the active substances that really exert the pharmacodynamic effects of S. chinensis lignans in organisms. 相似文献