高频燃烧–红外吸收法测定低合金钢中的碳含量

采用高频红外碳硫分析仪测定低合金钢中的碳含量。分别考察了取样量、助熔剂种类、助熔剂用量对测量结果的影响。结果显示当取样量为400 mg、钨助熔剂用量为样品取样量的1.2倍时,测定低合金钢中的碳含量效果最好,测定结果的相对标准偏差为0.9%(n=10),加标回收率在97.5%~102.7%之间。     

External-Radiation-Induced Local Hydroxylation Enables Remote Release of Functional Molecules in Tumors

Radiation-induced cleavage for controlled release in vivo is yet to be established. We demonstrate the use of 3,5-dihydroxybenzyl carbamate (DHBC) as a masking group that is selectively and efficiently removed by external radiation in vitro and in vivo. DHBC reacts mainly with hydroxyl radicals produced by radiation to afford hydroxylation at para/ortho positions, followed by 1,4- or 1,6-elimination to rescue the functionality of the client molecule. The reaction is rapid and can liberate functional molecules under physiological conditions. This controlled-release platform is compatible with living systems, as demonstrated by the release of a rhodol fluorophore derivative in cells and tumor xenografts. The combined benefits of the robust caging group, the good release yield, and the independence of penetration depth make DHBC derivatives attractive chemical caging moieties for use in chemical biology and prodrug activation.     

Cellular Synthesis and X-ray Crystal Structure of a Designed Protein Heterocatenane

Herein, we report the biosynthesis of protein heterocatenanes using a programmed sequence of multiple post-translational processing events including intramolecular chain entanglement, in situ backbone cleavage, and spontaneous cyclization. The approach is general, autonomous, and can obviate the need for any additional enzymes. The catenane topology was convincingly proven using a combination of SDS-PAGE, LC-MS, size exclusion chromatography, controlled proteolytic digestion, and protein crystallography. The X-ray crystal structure clearly shows two mechanically interlocked protein rings with intact folded domains. It opens new avenues in the nascent field of protein-topology engineering.     

Interfacial Strain Release from the WS2/CsPbBr3 van der Waals Heterostructure for 1.7 V Voltage All-Inorganic Perovskite Solar Cells

Perovskite lattice distortion induced by residual tensile strain from the thermal expansion mismatch between the electron-transporting layer (ETL) and perovskite film causes a sluggish charge extraction and transfer dynamics in all-inorganic CsPbBr₃ perovskite solar cells (PSCs) because of their higher crystallization temperatures and thermal expansion coefficients. Herein, the interfacial strain is released by fabricating a WS₂/CsPbBr₃ van der Waals heterostructure owing to their matched crystal lattice structure and the atomically smooth dangling bond-free surface to act as a lubricant between ETL and CsPbBr₃ perovskite. Arising from the strain-released interface and condensed perovskite lattice, the best device achieves an efficiency of 10.65 % with an ultrahigh open-circuit voltage of 1.70 V and significantly improved stability under persistent light irradiation and humidity (80 %) attack over 120 days.     

新型膦胺配体羰基钌化合物的合成及其催化性能研究

以十二羰基三钌和o-PPh2C6H4NR2(R=H,Me)配体为原料,成功制备了三种新型羰基钌化合物(μ-o-PPh2-C6H4NH)Ru3(μ-H)(CO)9(2)、(o-PPh2C6H4NH)2Ru(CO)2(3)和(μ-o-PPh2C6H4NMe2)2Ru(CO)3(4).对这三个化合物进行了核磁共振和红外谱学、元素分析和X射线单晶衍射分析表征,并对这三个化合物进行了催化性能研究.化合物2和4可催化苯甲醛加氢反应生成苯甲醇,但是3没有催化活性.从实验角度阐述了膦胺配体钌催化剂的结构与性能关联,进一步探讨了加氢催化反应失活的可能原因.     

Graphitic Carbon Nitride (g-C3N4): An Interface Enabler for Solid-State Lithium Metal Batteries

Solid-state Li metal batteries (SSLMBs) have attracted considerable interests due to their promising energy density as well as high safety. However, the realization of a well-matched Li metal/solid-state electrolyte (SSE) interface remains challenging. Herein, we report g-C₃N₄ as a new interface enabler. We discover that introducing g-C₃N₄ into Li metal can not only convert the Li metal/garnet-type SSE interface from point contact to intimate contact but also greatly enhance the capability to suppress the dendritic Li formation because of the greatly enhanced viscosity, decreased surface tension of molten Li, and the in situ formation of Li₃N at the interface. Thus, the resulting Li-C₃N₄|SSE|Li-C₃N₄ symmetric cell gives a significantly low interfacial resistance of 11 Ω cm² and a high critical current density (CCD) of 1500 μA cm⁻². In contrast, the same symmetric cell configuration with pristine Li metal electrodes has a much larger interfacial resistance (428 Ω cm²) and a much lower CCD (50 μA cm⁻²).     

A Hydrolytically Stable Vanadium(IV) Metal–Organic Framework with Photocatalytic Bacteriostatic Activity for Autonomous Indoor Humidity Control

Metal–organic frameworks (MOFs) with long-term stability and reversible high water uptake properties can be ideal candidates for water harvesting and indoor humidity control. Now, a mesoporous and highly stable MOF, BIT-66 is presented that has indoor humidity control capability and a photocatalytic bacteriostatic effect. BIT-66 (V₃(O)₃(H₂O)(BTB)₂), possesses prominent moisture tunability in the range of 45–60 % RH and a water uptake and working capacity of 71 and 55 wt %, respectively, showing good recyclability and excellent performance in water adsorption–desorption cycles. Importantly, this MOF demonstrates a unique photocatalytic bacteriostatic behavior under visible light, which can effectively ameliorate the bacteria and/or mold breeding problem in water adsorbing materials.     

可持续高分子-纤维素新材料研究进展

21世纪"绿色"化学已成为世界各国社会经济发展中的研究与开发战略方向.纤维素是自然界中储量最丰富的天然高分子,是重要的可再生资源以及未来的主要工业原料.然而由于纤维素存在着大量的分子内以及分子间氢键,其结构致密,难以溶解或熔融进一步加工.本文简要介绍了近几年来关于直接使用物理溶剂方法(非衍生化)对纤维素材料开发利用的新进展,主要包括以下4个方面:(1)纤维素在"绿色"溶剂-碱/尿素以及离子液体体系中的溶解和再生;(2)纳米纤维素的制备以及组装;(3)木材纳米技术的开发及利用;(4)细菌纤维素基材料等,旨在推进"绿色"技术实现纤维素资源的研究开发及利用.     

“Weakley型稀土多金属氧酸盐的制备与发光性质”在无机化学实验教学中的应用

采用理论与实验相结合的方法对稀土多金属氧酸盐的发光性质进行探究。首先,通过常规水溶液法合成了一系列稀土多金属氧簇Na9LnW10O36(Ln^3+=Sm^3+、Eu^3+、Tb^3+、Dy^3+);其次,利用粉末X射线衍射、红外光谱、拉曼光谱对簇合物的结构进行表征;最后,利用紫外-可见光谱、荧光光谱对簇合物的光学性质进行考查。通过系统性的实验使学生对稀土簇合物的结构表征以及发光性质有全面、深刻的认识。     

Diphenyl cyclopropenone-centered polymers for site-specific CO-releasing and chain dissociation

The synthesis and stimuli-responsiveness of a diphenyl cyclopropenone(DPCP)-centered poly(methyl acrylate)(PMA)are presented.DPCP-centered PMA could release carbon monoxide(CO)upon UV light in a switched on-and-off manner.The CO-releasing process can be reported by the variations in photoluminescence spectra.In addition,DPCP moiety covalently embedded in the crosslinked polyurethane could also release CO under UV light.Of special,DPCP-centered PMA in solution was selectively dissociated at the phenol ester bond under the ultrasound,and a force-induced hydrolyzation reaction was revealed by D20 exchanging^1 H NMR spectra.The kinetic study reveals that small quantity of water could enhance the chain scission rate.This work provides a DPCP-centered polymer for sitespecific CO-releasing and chain dissociation.