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921.
Jian‐Qiang Huang Chun‐Yu Ho 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(17):5758-5762
A cross‐hydroalkenylation/rearrangement cascade (HARC), using a cyclopropene and alkyne as substrate pairs, was achieved for the first time by using new [(NHC)Ni(allyl)]BArF catalysts (NHC=N‐heterocyclic carbenes). By controlling the (NHC)NiIIH relative insertion reactivity with cyclopropene and alkyne, a broad scope of cyclopentadienes was obtained with highly selectively. The structural features of the new (NHC)NiII catalyst were important for the success of the reaction. The mild reaction conditions employed may serve as an entry for exploring (NHC)NiII‐assisted vinylcyclopropane rearrangement reactivity. 相似文献
922.
Chuanqi Peng Jing Xu Mengxiao Yu Xuhui Ning Yingyu Huang Bujie Du Elizabeth Hernandez Payal Kapur Jer‐Tsong Hsieh Jie Zheng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(25):8567-8571
Precise control of in vivo transport of anticancer drugs in normal and cancerous tissues with engineered nanoparticles is key to the future success of cancer nanomedicines in clinics. This requires a fundamental understanding of how engineered nanoparticles impact the targeting‐clearance and permeation‐retention paradoxes in the anticancer‐drug delivery. Herein, we systematically investigated how renal‐clearable gold nanoparticles (AuNPs) affect the permeation, distribution, and retention of the anticancer drug doxorubicin in both cancerous and normal tissues. Renal‐clearable AuNPs retain the advantages of the free drug, including rapid tumor targeting and high tumor vascular permeability. The renal‐clearable AuNPs also accelerated body clearance of off‐target drug via renal elimination. These results clearly indicate that diverse in vivo transport behaviors of engineered nanoparticles can be used to reconcile long‐standing paradoxes in the anticancer drug delivery. 相似文献
923.
Qing Yao Bolong Huang Nan Zhang Mingzi Sun Qi Shao Xiaoqing Huang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(39):14121-14126
Channel‐rich RuCu snowflake‐like nanosheets (NSs) composed of crystallized Ru and amorphous Cu were used as efficient electrocatalysts for oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and overall water splitting in pH‐universal electrolytes. The optimized RuCu NSs/C‐350 °C and RuCu NSs/C‐250 °C show attractive activities of OER and HER with low overpotentials and small Tafel slopes, respectively. When applied to overall water splitting, the optimized RuCu NSs/C can reach 10 mA cm?2 at cell voltages of only 1.49, 1.55, 1.49 and 1.50 V in 1 m KOH, 0.1 m KOH, 0.5 m H2SO4 and 0.05 m H2SO4, respectively, much lower than those of commercial Ir/C∥Pt/C. The optimized electrolyzer exhibits superior durability with small potential change after up to 45 h in 1 m KOH, showing a class of efficient functional electrocatalysts for overall water splitting. 相似文献
924.
Clustering Algorithms to Analyze Molecular Dynamics Simulation Trajectories for Complex Chemical and Biological Systems? 下载免费PDF全文
Molecular dynamics (MD) simulation has become a powerful tool to investigate the structurefunction relationship of proteins and other biological macromolecules at atomic resolution and biologically relevant timescales. MD simulations often produce massive datasets containing millions of snapshots describing proteins in motion. Therefore, clustering algorithms have been in high demand to be developed and applied to classify these MD snapshots and gain biological insights. There mainly exist two categories of clustering algorithms that aim to group protein conformations into clusters based on the similarity of their shape (geometric clustering) and kinetics (kinetic clustering). In this paper, we review a series of frequently used clustering algorithms applied in MD simulations, including divisive algorithms, agglomerative algorithms (single-linkage, complete-linkage, average-linkage, centroid-linkage and ward-linkage), center-based algorithms (K-Means, K-Medoids, K-Centers, and APM), density-based algorithms (neighbor-based, DBSCAN, density-peaks, and Robust-DB), and spectral-based algorithms (PCCA and PCCA+). In particular, differences between geometric and kinetic clustering metrics will be discussed along with the performances of different clustering algorithms. We note that there does not exist a one-size-fits-all algorithm in the classification of MD datasets. For a specific application, the right choice of clustering algorithm should be based on the purpose of clustering, and the intrinsic properties of the MD conformational ensembles. Therefore, a main focus of our review is to describe the merits and limitations of each clustering algorithm. We expect that this review would be helpful to guide researchers to choose appropriate clustering algorithms for their own MD datasets. 相似文献
925.
Erbo Cheng Shoushuang Huang Dayong Chen Ruting Huang Qing Wang Zhangjun Hu Yong Jiang Zhen Li Bing Zhao Zhiwen Chen 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(7):969-978
Metal oxides have a large storage capacity when employed as anode materials for lithium‐ion batteries (LIBs). However, they often suffer from poor capacity retention due to their low electrical conductivity and huge volume variation during the charge–discharge process. To overcome these limitations, fabrication of metal oxides/carbon hybrids with hollow structures can be expected to further improve their electrochemical properties. Herein, ZnO‐Co3O4 nanocomposites embedded in N‐doped carbon (ZnO‐Co3O4@N‐C) nanocages with hollow dodecahedral shapes have been prepared successfully by the simple carbonizing and oxidizing of metal–organic frameworks (MOFs). Benefiting from the advantages of the structural features, i.e. the conductive N‐doped carbon coating, the porous structure of the nanocages and the synergistic effects of different components, the as‐prepared ZnO‐Co3O4@N‐C not only avoids particle aggregation and nanostructure cracking but also facilitates the transport of ions and electrons. As a result, the resultant ZnO‐Co3O4@N‐C shows a discharge capacity of 2373 mAh g?1 at the first cycle and exhibits a retention capacity of 1305 mAh g?1 even after 300 cycles at 0.1 A g?1. In addition, a reversible capacity of 948 mAh g?1 is obtained at a current density of 2 A g?1, which delivers an excellent high‐rate cycle ability. 相似文献
926.
Deng B Wang Z Song J Xiao Y Chen D Huang J 《Analytical and bioanalytical chemistry》2011,401(7):2143-2152
The doxorubicin (DOX) uptake in single human leukemia K562 cells with changes in both drug dosage and exposure period was
studied using capillary electrophoresis (CE) coupled with laser-induced fluorescence (LIF) detection. The cells were treated
with DOX at different concentrations (1, 3, 10, 20, 30, and 50 μM) and for different exposure times (1, 3, 5, 24, and 48 h).
At least 20 cells were analyzed for each DOX-treated cell population. A marked heterogeneity in DOX uptake among single cells
was observed, because the relative standard deviation of the uptake of DOX by single cells ranged from 24.0% to 61.1% within
each cell population. The cell-to-cell heterogeneity in DOX uptake first decreased and then became constant with increasing
drug concentration, but it did not exhibit regular variation with increasing exposure time. The mean DOX uptake was a linear
function of drug concentration (r ≥ 0.9667). In terms of the correlation with exposure time, the mean DOX uptake reached its maximum at 3 h for the cell populations
treated with 1–10 μM DOX, while it kept increasing during 48 h exposure of cell populations to 20–50 μM DOX. Because it eliminates
DOX fluorescence quenching and sample loss, the CE-LIF method directly detects the true DOX uptake by single cells, and thus
presents accurate information on both the cell-to-cell heterogeneity in DOX uptake and the patterns of DOX uptake in K562
cells as functions of drug concentration and exposure time. 相似文献
927.
Kuihua ZhangChen Huang Chunyang WangXiumei Mo Salem S. Al-DeyabMohamed El-Newehy 《Polymer Degradation and Stability》2011,96(12):2266-2275
Nanofibrous scaffolds of silk fibroin (SF) and poly(l-lactic acid-co-?-caprolactone) (P(LLA-CL)) blends fabricated via electrospinning possessed good mechanical property and biocompatibility, as demonstrated by a previous study in vitro. However, the degradation behavior of the scaffolds, which may significantly influence tissue repair and regeneration, needs further exploration. In this study, in vitro degradation of pure SF, P(LLA-CL) and SF/P(LLA-CL) blended nanofibrous scaffolds were performed in phosphate-buffered saline (PBS, pH 7.4 ± 0.1) at 37 °C for 6 months. A series of analyses and characterizations (including morphologic changes, loss weight, pH changes of PBS solutions, DSC, XRD and FTIR-ATR) were conducted to the nanofibrous scaffolds after degradation and the results showed that the pure SF nanofibrous scaffolds were not completely degradable in PBS while pure P(LLA-CL) nanofibrous scaffolds had the fastest degradation rate. Moreover, the addition of SF reduced the degradation rate of P(LLA-CL) in SF/P(LLA-CL) blended nanofibrous scaffolds. This was probably caused by the intermolecular interactions between SF and P(LLA-CL), which hindered the movement of P(LLA-CL) molecular chains. 相似文献
928.
A method is proposed for creating a non-equilibrium ensemble with a constant number of molecules, constant temperature and constant pressures with different target values in two reservoirs [referred to as NT(P(1)-P(2)) ensemble] that are connected by a finite length nanopore. This method includes two steps. The first step places a partition between the two reservoirs and then creates a static pressure field and a proper system volume by using two self-adjusting plates on which two external forces/pressures with different target values are exerted. The second step removes the partition and the two self-adjusting plates and the pressure difference between the two reservoirs is maintained by a "pump" designed to simultaneously create a periodic boundary condition between the two reservoirs and supply the necessary force (work) to a subset of molecules for a steady state flow. To examine this method, several cases using liquid argon with a truncated and shift Lennard-Jones potential under different target pressures and pump sizes were studied. Results show that the method proposed in this paper works well. In addition, the method proposed in this paper was compared with the other external force field methods. The results show that as long as the external force is applied to a restricted set of molecules away from the channel a constant pressure difference between two reservoirs is maintained. The advantage of the algorithm proposed here also sets the absolute pressures with different target levels in two reservoirs instead of it being arbitrary. Studies show that the fluid flow rate or permeability through a nanopore depends not only on the pressure difference between two reservoirs, but also on the absolute pressures in two reservoirs. 相似文献
929.
Guanglei LvGenping Huang Guangyou ZhangChangduo Pan Fan Chen Jiang Cheng 《Tetrahedron》2011,67(26):4879-4886
A rhodium or palladium-catalyzed addition of boronic acids to phthalaldehydonitrile, followed by an intramolecular lactonization of cyano to access 3-substituted phthalides, is described. This procedure tolerates a series of functional groups, such as methoxy, fluoro, chloro, and vinyl groups. It is a novel procedure for the synthesis of 3-arylphthalides. 相似文献
930.
Asymmetric total syntheses of heliannuol E and epi-heliannuol E were achieved in 10 and 13 steps, respectively, from the commercially available starting materials. The syntheses feature an intramolecular attacking on the sulfate to form the dihydropyran ring of heliannuol E and an acyl transfer-secondary carbocation capture sequence to construct the dihydropyran ring of epi-heliannuol E. 相似文献