Cu?Cu2O?TiO2 Nanojunction Systems with an Unusual Electron–Hole Transportation Pathway and Enhanced Photocatalytic Properties

Multicomponent Cu? Cu₂O? TiO₂ nanojunction systems were successfully synthesized by a mild chemical process, and their structure and composition were thoroughly analyzed by X‐ray diffraction, transmission electron microscopy, field‐emission scanning electron microscopy, and X‐ray photoelectron spectroscopy. The as‐prepared Cu? Cu₂O? TiO₂ (3 and 9 h) nanojunctions demonstrated higher photocatalytic activities under UV/Vis light irradiation in the process of the degradation of organic compounds than those of the Cu? Cu₂O, Cu? TiO₂, and Cu₂O? TiO₂ starting materials. Moreover, time‐resolved photoluminescence spectra demonstrated that the quenching times of electrons and holes in Cu? Cu₂O? TiO₂ (3 h) is higher than that of Cu? Cu₂O? TiO₂ (9 h); this leads to a better photocatalytic performance of Cu? Cu₂O? TiO₂ (3 h). The improvement in photodegradation activity and electron–hole separation of Cu? Cu₂O? TiO₂ (3 h) can be ascribed to the rational coupling of components and dimensional control. Meanwhile, an unusual electron–hole transmission pathway for photocatalytic reactions over Cu? Cu₂O? TiO₂ nanojunctions was also identified.     

金属离子催化β-内酰胺类抗生素水解的荧光光谱研究

研究并比较了4种金属离子Hg(Ⅱ）、Mn（Ⅱ）、Zn（Ⅱ）、Cd（Ⅱ）在碱性条件下催化β-内酰胺类抗生素水解的能力,发现Hg(Ⅱ）、Zn（Ⅱ）对β-内酰胺类抗生素水解的催化作用效果良好,而Mn(Ⅱ）和Cd(Ⅱ)对长效青霉素水解的催化作用效果不明显。提出了分别在Hg(Ⅱ)和Zn(Ⅱ)催化作用下测定β-内酰胺类抗生素的荧光光谱分析法,并用于体液中抗生素残留物的检测。     

钕在小鼠体内的分布与蓄积及对孕酮分泌的影响

应用核素示踪方法研究147Nd在小鼠体内的分布、蓄积及其对孕酮分泌的影响.一次性腹腔注射200mg@kg-1147Nd在各组织中呈不均匀分布,骨骼中表现出了高度蓄积性,且随时间的延长而增加;在眼睛、血液和大脑中均有一定的蓄积,但因排泄和体内再分配随时间而呈下降趋势;在Nd处理后血清中孕酮浓度显著低于对照组,表现了明显的抑制作用.     

铈及氟铈联用对CaHPO_4·2H_2O在水溶液中的转化产物的影响

以XRD和IR为表征手段 ,以恒pH法为溶解实验方法 ,研究了 37℃下以铈单独处理和氟铈联用处理对二水磷酸氢钙 (CaHPO4 ·2H2 O ,DCPD)的水化产物及其溶解性质的影响。Ce3 不能促进DCPD向磷灰石转化 ,氟铈联用可加快DCPD的转化。随着Ce3 浓度的提高 ,DCPD经含Ce溶液单独处理后的产物主要为CaHPO4 (DCPA) Ce(PO4 )和Ce(PO4 )。DCPD经氟铈联用处理后的产物主要为DCPA (Ca2 ,Ce3 ) 1 0 -x(PO4 ) 6 -yF2 (F Ce HAP) Ce(PO4 )和F Ce HAP Ce(PO4 )。经 1?Cl3溶液单独处理后的DCPD的抗酸能力已有显著提高。氟铈联用促进溶解度更低的F Ce HAP的形成 ,因此效果优于铈单独处理 ,有可能成为一种有效的防龋方法。     

Monobromination of Activated Aromatic Compounds with Polyvinylbenzyltriphenylphosphonium Supported Tribromide

Chloromethylated crosslinked co‐polyvinylbenzene‐divinylbenzene (2% DVB) was treated with triphenylphosphine and then with sodium bromate and hydrobromic add to afford red colored insoluble polyvinylbenzyltriphenylphosphonium supported tribromide. This reagent could be used as a mild and efficient monobrominating reagent for activated aromatic compounds such as phenols, aromatic ethers, aromatic amines and acetylanilines with good yields and high para‐selectivity.     

Leiocyclocin A and B, Two Cyclopeptides from Goniothalamus leiocarpus

Ongoing phytochemical studies on Goniothalamus species have led to the isolation of a number of annonaceous acetogenins and unusual new styryllactones which were found to possess significant cytotoxic activities against several hunan tumour cell lines1,2. Firstly, cyclopeptides were reported to be isolated from genus Goniothalamus in this paper.Goniothalamus leiocarpus is an evergreen tree which grows in the south of Yunnan, China. Four new anticancer styryllactones3,4 from the stem bark and…     

原子吸收光谱法测定电解金属锰中微量金属杂质元素

本文用盐酸溶解样品,火焰原子吸收光谱法测定电解金属锰中K,Na,Ca,Mg,Fe,石墨炉原子吸收光谱法测定其中的Cr,Cu,Co,Ni含量。对测定条件进行了实验,找出最佳溶样方法和酸度,对共存元素的干扰有排除亦进行了试验,获得了满意的效果。该法简便、快速、准确,加标回收率为88.9%-108.7%之间,相对标准偏差为0.6%-6.7%,标准曲线法、标准加入法结果与对照结果相吻合,适用于电解金属锰样品金属杂质元素的分析。     

Theoretical and Experimental Analysis of the Reaction Mechanism of MrTPS2, a Triquinane‐Forming Sesquiterpene Synthase from Chamomile

Terpene synthases, as key enzymes of terpene biosynthesis, have garnered the attention of chemists and biologists for many years. Their carbocationic reaction mechanisms are responsible for the huge variety of terpene structures in nature. These mechanisms are amenable to study by using classical biochemical approaches as well as computational analysis, and in this study we combine quantum‐chemical calculations and deuterium‐labeling experiments to elucidate the reaction mechanism of a triquinane forming sesquiterpene synthase from chamomile. Our results suggest that the reaction from farnesyl diphosphate to triquinanes proceeds through caryophyllyl and presilphiperfolanyl cations and involves the protonation of a stable (?)‐(E)‐β‐caryophyllene intermediate. A tyrosine residue was identified that appears to be involved in the proton‐transfer process.     

One‐pot Synthesis of Tetrahydrobenzo[b]pyrans Catalyzed by PEG‐1000 Bridged Primary Amine Functionalized Dicationic Ionic Liquid in Water

A novel poly (ethylene glycol) bridged primary amine functionalized dicationic ionic liquid ([PA‐PEG₁₀₀₀‐DIL][BF₄]) was synthesized and characterized by ¹H‐NMR, ¹³C‐NMR, FT‐IR and ESI‐MS. The thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis indicated the high thermal stability of [PA‐PEG₁₀₀₀‐DIL][BF₄]. It was used as an efficient and recyclable catalyst for the synthesis of substituted tetrahydrobenzo[b]pyrans through a one‐pot three‐component condensation of aromatic aldehydes, malononitrile and dimedone in 86% ～ 96% yields within 10 ～ 30 min in water. This method offers several advantages such as mild reaction conditions, simple operation and environmental friendliness. Furthermore, the catalyst could be easily recovered and reused for at least five runs without obvious loss of catalytic activity.     

A numerical investigation of electrohydrodynamic (EHD) effects on bubble deformation under pseudo-nucleate boiling conditions

In this article, the electrohydrodynamic (EHD) effects on nucleate boiling are studied by developing a numerical modelling of EHD effect on bubble deformation in pseudo-nucleate boiling conditions. The volume of fluid (VOF) method is employed to track the interface between the gas–liquid two phases; the user-defined code is written and added to the commercial software FLUENT to solve the electric field and the corresponding electric body force. On this basis, the model is applied to study the EHD effects on heat transfer and fluid flows. An initial air bubble surrounded by liquid CCl₄ and attached to a horizontal superheated wall under the action of electric field is studied. The results of the EHD effect on bubble shape evolution are compared with those of available experiments showing good agreement. The mechanism of EHD enhancement of heat transfer and the EHD induced phenomena including bubble elongation and detachment are analyzed in detail.