Anti-Markovnikov Hydroamination of Racemic Allylic Alcohols to Access Chiral γ-Amino Alcohols

A ruthenium-catalyzed formal anti-Markovnikov hydroamination of allylic alcohols for the synthesis of chiral γ-amino alcohols is presented. Proceeding via an asymmetric hydrogen-borrowing process, the catalysis allows racemic secondary allylic alcohols to react with various amines, affording enantiomerically enriched chiral γ-amino alcohols with broad substrate scope and excellent enantioselectivities (68 examples, up to >99 % ee).     

An Activatable AIEgen Probe for High‐Fidelity Monitoring of Overexpressed Tumor Enzyme Activity and Its Application to Surgical Tumor Excision

Monitoring fluctuations in enzyme overexpression facilitates early tumor detection and excision. An AIEgen probe (DQM‐ALP) for the imaging of alkaline phosphatase (ALP) activity was synthesized. The probe consists of a quinoline‐malononitrile (QM) core decorated with hydrophilic phosphate groups as ALP‐recognition units. The rapid liberation of DQM‐OH aggregates in the presence of ALP resulted in aggregation‐induced fluorescence. The up‐regulation of ALP expression in tumor cells was imaged using DQM‐ALP. The probe permeated into 3D cervical and liver tumor spheroids for imaging spatially heterogeneous ALP activity with high spatial resolution on a two‐photon microscopy platform, providing the fluorescence‐guided recognition of sub‐millimeter tumorigenesis. DQM‐ALP enabled differentiation between tumor and normal tissue ex vivo and in vivo, suggesting that the probe may serve as a powerful tool to assist surgeons during tumor resection.     

Linear Dispersion Relation of Asymmetric Modes in the Axisymmetric Slow-Wave Structure

The linear dispersion relation of asymmetric electromagnetic modes in the corrugated-wall waveguide is derived and calculated numerically. The numerical analyses indicate that the effects of lower asymmetric modes on the main interaction mode TM_m must be considered and mode selection also must be solved in order to realize the single asymmetric mode operation of the oversized structures.     

Supersaturation controlled growth of MAFAPbI<Subscript>3</Subscript> perovskite film for high efficiency solar cells

Controlling the nucleation and growth of organic-inorganic hybrids perovskite is of key importance to improve the morphology and crystallinity of perovskite films. However, the growth mechanism of perovskite films based on classical crystallization theory is not fully understood. Here, we develop a supersaturation controlled strategy (SCS) to balance the nucleation and crystal growth speeds. By this strategy, we are able to find an ideal supersaturation region to realize a balance of nucleation and crystal growth, which yields highly crystallized perovskite films with micrometer-scale grains. Besides, we provide a thoughtful analysis of nucleation and growth based on the fabrication of the perovskite films. As a result, the highest photovoltaic power conversion efficiencies (PCE) of 19.70% and 20.31% are obtained for the planar and the meso-superstructured devices, respectively. This strategy sheds some light for understanding the film growth mechanism of high quality perovskite film, and it provides a facile strategy to fabricate high efficiency perovskite solar cells.     

Supersaturation controlled growth of MAFAPbI_3 perovskite film for high efficiency solar cells

Controlling the nucleation and growth of organic-inorganic hybrids perovskite is of key importance to improve the morphology and crystallinity of perovskite films. However, the growth mechanism of perovskite films based on classical crystallization theory is not fully understood. Here, we develop a supersaturation controlled strategy(SCS) to balance the nucleation and crystal growth speeds. By this strategy, we are able to find an ideal supersaturation region to realize a balance of nucleation and crystal growth, which yields highly crystallized perovskite films with micrometer-scale grains. Besides, we provide a thoughtful analysis of nucleation and growth based on the fabrication of the perovskite films. As a result, the highest photovoltaic power conversion efficiencies(PCE) of 19.70% and 20.31% are obtained for the planar and the meso-superstructured devices, respectively. This strategy sheds some light for understanding the film growth mechanism of high quality perovskite film, and it provides a facile strategy to fabricate high efficiency perovskite solar cells.     

AR-Ag(Ⅰ)体系的共振散射光谱法测定痕量银

在pH=4.4的NaAc-HAc缓冲介质和2.0×10-3mol/L十二烷基苯磺酸钠(SDBS)溶液中,Ag(Ⅰ)与茜素红(AR)可形成较稳定的离子缔合物微粒,其在324、360和500nm处分别产生3个较强的共振散射峰.在最佳实验条件下,浓度在0.022～2.160μg/mL之间的Ag(Ⅰ)与共振散射强度△I324nm呈较好的线性关系,检测限为0.139 ng/mL.据此,建立了一种测定痕量银的共振散射新方法,并将该方法用于废胶片中痕量银的测定.     

Accurate localization and relative quantification of arginine methylation using nanoflow liquid chromatography coupled to electron transfer dissociation and drbitrap mass spectrometry

Protein arginine (Arg) methylation serves an important functional role in eucaryotic cells, and typically occurs in domains consisting of multiple Arg in close proximity. Localization of methylarginine (MA) within Arg-rich domains poses a challenge for mass spectrometry (MS)-based methods; the peptides are highly charged under electrospray ionization (ESI), which limits the number of sequence-informative products produced by collision induced dissociation (CID), and loss of the labile methylation moieties during CID precludes effective fragmentation of the peptide backbone. Here the fragmentation behavior of Arg-rich peptides was investigated comprehensively using electron-transfer dissociation (ETD) and CID for both methylated and unmodified glycine-/Arg-rich peptides (GAR), derived from residues 679–695 of human nucleolin, which contains methylation motifs that are widely-represented in biological systems. ETD produced abundant information for sequencing and MA localization, whereas CID failed to provide credible identification for any available charge state (z=2–4). Nevertheless, CID produced characteristic neutral losses that can be employed to distinguish among different types of MA, as suggested by previous works and confirmed here with product ion scans of high accuracy/resolution by an LTQ/Orbitrap. To analyze MA-peptides in relatively complex mixtures, a method was developed that employs nano-LC coupled to alternating CID/ETD for peptide sequencing and MA localization/characterization, and an Orbitrap for accurate precursor measurement and relative quantification of MA-peptide stoichiometries. As proof of concept, GAR-peptides methylated in vitro by protein arginine N-methyltransferases PRMT1 and PRMT7 were analyzed. It was observed that PRMT1 generated a number of monomethylated (MMA) and asymmetric-dimethylated peptides, while PRMT7 produced predominantly MMA peptides and some symmetric-dimethylated peptides. This approach and the results may advance understanding of the actions of PRMTs and the functional significance of Arg methylation patterns.     

多元统计分析在塔里木瓦吉里塔格钒钛磁铁矿床多元素相关性及成矿预测研究中的应用

塔里木巴楚县瓦吉里塔格地区出露有与塔里木早二叠世大火成岩省的形成密切相关的大型钒钛磁铁矿床. 基于多元统计分析对该矿区露头和大量钻孔岩心样品中Fe-Ti-V元素和部分主量元素数据开展了元素地球化学相关性研究. 采用SPSS软件对大量数据进行相关分析和回归分析,计算各元素间的相关系数,Fe、Ti、V 3种元素的相关性分析结果表明： 矿床中Fe、Ti和V之间均呈正相关, 成矿元素与造岩元素之间存在负相关关系;建立伴生钒元素与铁和钛元素之间关系的回归方程V=-4.984+0.360 Fe+0.984Ti,由Fe和Ti元素质量分数可以估算伴生组分V的质量分数.利用Matlab软件的可视化功能,绘制了Fe-Ti-V元素质量分数的三维立体图,建立空间模型,发现Fe₂O_3T、TiO₂和V₂O₅品位较高的位置相对一致,均主要分布于研究区北部中间一带,富集在辉石岩中. 该空间模型的建立有助于识别矿体和非矿体的分布范围和富集趋势,并进行成矿预测. 此项研究对钒元素含量的精确估算和矿藏勘探有一定的指导意义.     

火试金-原子吸收光谱法测定锡阳极泥中金、银含量

锡阳极泥是锡冶炼过程中的一种中间产物,其中含有大量的金、银等贵金属。准确测定锡阳极泥中金、银含量有很重要的现实意义。采用火试金法能实现锡阳极泥中金、银含量的连续测定,方法准确度高,精密度好,金、银回收率在97.46%~101.66%,能很好地满足锡阳极泥中高品位金、银的测定。     

活性炭吸附-火焰原子吸收光谱法测定粗硒中的金

建立了活性炭吸附-火焰原子吸收光谱法测定粗硒中金量的分析方法。讨论了称样量、溶样条件和活性炭的灰化程度对金量测定的影响,并且对火焰原子吸收光谱法与火试金法测定粗硒中的金量做了比较。火焰原子吸收光谱法和火试金法测定的相对标准偏差分别为1.3%~5.9%和0.91%~7.8%;加标回收率分别为93.1%~100.7%和94.8%~102.2%。结果表明,方法有较好的精密度和准确度,并且具有较强的实用性。