All solid-state sum-frequency generation of 1.12-W continuous-wave laser at 588 nm

A new resonator design for doubly resonant continuous-wave (CW) intracavity sum-frequency mixing (SFM) is reported. 1.12 W of coherent radiation at 588 nm is generated by mixing 1062-nm Nd:GdVO4laser and 1319-nm Nd:YAG laser. The optical-to-optical conversion efficiency is up to 3.7%.     

Use of a long-spacer-side-chain liquid crystalline polysiloxane containing a crown ether as a stationary phase for capillary gas chromatography

A new kind of side chain liquid crystalline polysiloxane containing a crown ether with a longer spacer (PSC-11) has been prepared and coated on a fused silica capillary column. The main chroma-tographic characteristics including efficiency, polarity, and selectivity have been examined. The phase exhibits the retention properties of both liquid crystal and crown ether stationary phases and possesses higher efficiency and better selectivity than PSC-3, which has a shorter spacer between the main polysiloxane chain and liquid crystalline side chain.     

离子液体介导CO2化学转化研究进展

The efficient utilization of carbon dioxide (CO₂) as a C1 feedstock is of great significance for green and sustainable development. Therefore, the efficient chemical conversion of CO₂ into value-added products has recently attracted a lot of research attention in recent years. The transformation of CO₂ generally requires high-energy substrates, specific catalysts, and harsh reaction conditions due to its high thermodynamic stability and kinetic inertness. Consequently, several efforts have been dedicated toward the development of high-performance catalysts and new reaction routes for CO₂ conversion over the last few decades. To date, many routes of convert CO₂ into value-added chemicals have been proposed, together with the development of heterogeneous and homogeneous catalysts. Among the advanced catalysts reported to date, ionic liquids (ILs) have been widely investigated and show great potential for the efficient, selective, and economical conversion of CO₂ into highly valuable products under mild conditions, even under ambient conditions. Some task-specific ILs have been designed with unique functional groups (e.g., —OH, —SO₃H, —NH₂, —COOH, and —C≡N), which can act as the solvent, absorbent, activating agent, catalyst, or cocatalyst to realize the transformation of CO₂ under metal-free and mild conditions. In addition, a variety of catalytic systems composed of ILs and metal catalysts have also been reported for the transformation of CO₂, in which the combination of the IL and metal catalyst is responsible for CO₂ conversion with high efficiency. In this review article, we summarize the recent advances in IL-mediated CO₂ transformation into chemicals prepared via C—O, C—N, C—S, C—H, and C—C bond forming processes. ILs that can chemically capture CO₂ with high capacity are first introduced, which can activate CO₂ via the formation of IL-based carbonates or carbamates, thus realizing the transformation of CO₂ under metal-free and mild conditions. Recent progress in IL-mediated CO₂ transformations to form carbonates and various kinds of N- and S-containing compounds (e.g., oxazolidinones, ureas, benzimidazolones, formamides, methylamines, benzothiazoles, and other chemicals) as well as CO₂ hydrogenation to give formic acid, methane, acetic acid, low-carbon alcohols, and hydrocarbons has been summarized in this review with a focus on the reaction routes, catalytic systems, and reaction mechanism. In these reactions, ILs can simultaneously activate the substrate via strong H-bonding in addition to activating CO₂, and the cooperative effects among the ionic and molecular species and metal catalysts accomplish the reactions of CO₂ with various kinds of substrates to afford a wide range of value-added chemicals. Finally, the shortcomings and perspectives of ILs are discussed. In short, IL-mediated CO₂ transformations provide green and effective routes for the synthesis of high-value chemicals, which may have great potential for a wide range of applications.     

超高效合相色谱法快速检测塑料食品接触材料中13种紫外吸收剂

建立了一种同时检测塑料食品接触材料中13种紫外吸收剂的超高效合相色谱法。以甲醇为溶剂对塑料食品接触材料样品进行超声提取，经C18固相萃取柱净化，过0.22 μm有机滤膜，采用超高效合相色谱仪分析。选择ACQUTY UPC² HSS C18 SB色谱柱（150 mm×3.0 mm，1.8 μm），以超临界二氧化碳为流动相，异丙醇为改性剂进行梯度洗脱，在最优色谱条件下，13种紫外吸收剂能够在4 min内实现有效分离。结果表明，在各自线性范围内，13种紫外吸收剂的线性关系良好，标准曲线相关系数不低于0.9985，检出限（S/N=3）为0.05~0.15 mg/kg，加标回收率为86.8%~115.7%，相对标准偏差为0.73%~5.61%。该方法快速简便，准确可靠，同时大大减少了有机溶剂的消耗，可用于塑料食品接触材料中13种紫外吸收剂的快速检测。     

Evaluating and clustering retrosynthesis pathways with learned strategy

With recent advances in the computer-aided synthesis planning (CASP) powered by data science and machine learning, modern CASP programs can rapidly identify thousands of potential pathways for a given target molecule. However, the lack of a holistic pathway evaluation mechanism makes it challenging to systematically prioritize strategic pathways except for using some simple heuristics. Herein, we introduce a data-driven approach to evaluate the relative strategic levels of retrosynthesis pathways using a dynamic tree-structured long short-term memory (tree-LSTM) model. We first curated a retrosynthesis pathway database, containing 238k patent-extracted pathways along with ∼55 M artificial pathways generated from an open-source CASP program, ASKCOS. The tree-LSTM model was trained to differentiate patent-extracted and artificial pathways with the same target molecule in order to learn the strategic relationship among single-step reactions within the patent-extracted pathways. The model achieved a top-1 ranking accuracy of 79.1% to recognize patent-extracted pathways. In addition, the trained tree-LSTM model learned to encode pathway-level information into a representative latent vector, which can facilitate clustering similar pathways to help illustrate strategically diverse pathways generated from CASP programs.

Tree-structured long short-term memory neural model learns to understand the retrosynthesis design strategies from patent-extracted retrosynthetic pathway data.     

TiO_2/CuPc/NiFe-LDH photoanode for efficient photoelectrochemical water splitting

Photoelectrochemical(PEC) water splitting is a promising approach for renewable hydrogen production.However,the practical PEC solar-to-fuel conversion efficiency is still low owing to poor light absorption and rapid recombination of charge carriers in photoelectrode.In this work,we report a ternary photoanode with simultaneously enhancement of light absorption and water oxidation efficiency by introducing copper phthalocyanine(CuPc) and nickel iron-laye red double hydroxide(NiFe-LDH) on TiO_2(denoted as TiO_2/CuPc/NiFe-LDH).An experimental study reveals that CuPc loading on TiO_2 bring strong visible light absorption;NiFe-LDH as an oxygen evolution reaction catalyst efficiently accelerates the surface water oxidation reaction.This synergistic effect of CuPc and NiFe-LDH gives enhanced photocurrent density(2.10 mA/cm2 at 0.6 V vs.SCE) and excellent stability in the ternary TiO_2/CuPc/NiFeLDH photoanode.     

In Vitro Antifungal Activity and Mechanism of Ag3PW12O40 Composites against Candida Species

Fungal infections pose a serious threat to human health. Polyoxometalates (POMs) are metal–oxygen clusters with potential application in the control of microbial infections. Herein, the Ag₃PW₁₂O₄₀ composites have been synthesized and verified by Fourier transform infrared (FT-IR) spectrum, transmission electron microscopy (TEM), scanning electron microscope (SEM), elemental analysis, and X-ray diffraction (XRD). The antifungal activities of Ag₃PW₁₂O₄₀ were screened in 19 Candida species strains through the determination of minimum inhibitory concentration (MIC) by the microdilution checkerboard technique. The minimum inhibitory concentration (MIC₅₀) values of Ag₃PW₁₂O₄₀ are 2~32 μg/mL to the Candida species. The MIC₈₀ value of Ag₃PW₁₂O₄₀ to resistant clinical isolates C. albicans HL963 is 8 μg/mL, which is lower than the positive control, fluconazole (FLC). The mechanism against C. albicans HL963 results show that Ag₃PW₁₂O₄₀ can decrease the ergosterol content. The expressions of ERG1, ERG7, and ERG11, which impact on the synthesis of ergosterol, are all prominently upregulated by Ag₃PW₁₂O₄₀. It indicates that Ag₃PW₁₂O₄₀ is a candidate in the development of new antifungal agents.     

A Novel Synthesis of 2-Alkylthiobenzothiazoles and 2-Alkylthiobenzoxazoles

Abstract

3H-Benzothiazole-2-thione and 3H-benzoxazole-2-thione were selectively S-alkylated by use of O-alkylisoureas as the alkylating reagents. The reactions could be performed under mild reaction conditions in short reaction times, and high yields were obtained using O-primary-alkylisoureas, whereas low yields were obtained with sec- and tert-alkylisoureas.     

含环氧基团的聚合物微球固载2,2,6,6-四甲基哌啶氮氧自由基催化剂的制备及其催化分子氧氧化苯甲醇

以甲基丙烯酸缩水甘油酯(GMA)为单体, 以乙二醇二甲基丙烯酸酯(EGDMA)为交联剂, 采用悬浮聚合法制得交联聚甲基丙烯酸缩水甘油酯(CPGMA)微球, 然后以4-羟基-2,2,6,6-四甲基哌啶氮氧自由基(4-OH-TEMPO)为试剂, 使CPGMA微球表面的环氧基团发生开环反应, 从而制得了TEMPO固载化微球TEMPO/CPGMA, 考察了制备条件对固载化反应的影响, 并采用多种方法对微球TEMPO/CPGMA进行了表征. 将微球TEMPO/CPGMA与CuCl组成共催化体系, 用于分子氧氧化苯甲醇, 考察了反应条件对催化体系性能的影响. 结果表明, 以含环氧基团的聚合物微球CPGMA为载体, 通过开环反应, 可成功地实现TEMPO的固载化, 开环反应属S_N2亲核取代反应, 适宜采用溶剂N,N''-二甲基甲酰胺和反应温度85℃. 非均相催化剂TEMPO/CPGMA与助催化剂CuCl构成共催化体系, 在室温、常压O₂条件下可高效地将苯甲醇氧化为苯甲醛, 产物选择性和产率分别为100%和90%. 主催化剂TEMPO与助催化剂CuCl适宜的摩尔比为1:1.2; 主催化剂适宜用量为0.90 g. 此外, TEMPO/CPGMA固体催化剂具有良好的循环使用性能.     

室温合成二硫化二正丁基黄原酸酯及其表征

以正丁醇、氢氧化钠和二硫化碳为原料,水作溶剂合成正丁基黄原酸钠,再与一氯化硫反应,室温条件下合成对称的二硫化二正丁基黄原酸酯,并探讨了反应条件对合成正丁基黄原酸钠和二硫化二正丁基黄原酸酯产率的影响。通过红外(FT-IR)、核磁(1H NMR)、质谱(MS)及元素分析等技术手段确定了产物的结构。优化的合成条件为:n(正丁基黄原酸钠)∶n(S2Cl2)=2∶1.1,温度为室温,溶剂为THF,反应时间为2 min,产率可达83.2%,反应条件温和,反应迅速、收率高。