双极谱峰指示催化动力学极语法测定痕量钒

在硫酸介质中,以酒石酸为活化剂,痕量机对溴酸钾氧化乙基极的反应具有极强的催化作用,研究了最佳反应条件,且发现在氨性缓冲溶液中乙基橙及其氧化产物具有良好的极谱峰,以极谱法监测催化反应过程中乙基橙及其氧化产物浓度的变化,建立了催化动力学极谱法测定痕量帆的新方法。方法的线性范围为０．２５～３．５μｇ／Ｌ,检出限为０．１２μｇ／Ｌ。应用于食品中痕量钒的测定,结果满意。     

Two new XP(O)[NHC(CH3)3]2 phosphoramidates,with X = (CH3)2N and [(CH3)3CNH]2P(O)(O)

In N,N′‐di‐tert‐butyl‐N′′,N′′‐dimethylphosphoric triamide, C₁₀H₂₆N₃OP, (I), and N,N′,N′′,N′′′‐tetra‐tert‐butoxybis(phosphonic diamide), C₁₆H₄₀N₄O₃P₂, (II), the extended structures are mediated by P(O)...(H—N)₂ interactions. The asymmetric unit of (I) consists of six independent molecules which aggregate through P(O)...(H—N)₂ hydrogen bonds, giving R₂¹(6) loops and forming two independent chains parallel to the a axis. Of the 12 independent tert‐butyl groups, five are disordered over two different positions with occupancies ranging from to . In the structure of (II), the asymmetric unit contains one molecule. P(O)...(H—N)₂ hydrogen bonds give S(6) and R₂²(8) rings, and the molecules form extended chains parallel to the c axis. The structures of (I) and (II), along with similar structures having (N)P(O)(NH)₂ and (NH)₂P(O)(O)P(O)(NH)₂ skeletons extracted from the Cambridge Structural Database, are used to compare hydrogen‐bond patterns in these families of phosphoramidates. The strengths of P(O)[...H—N]_x (x = 1, 2 or 3) hydrogen bonds are also analysed, using these compounds and previously reported structures with (N)₂P(O)(NH) and P(O)(NH)₃ fragments.     

Label‐Free,Non‐Derivatization CRET Detection Platform for 6‐Mercaptopurine Based on the Distance‐Dependent Optical Properties of Gold Nanoparticles

A label‐free, non‐derivatization chemiluminescence resonance energy transfer (CRET) detection platform has been developed for the detection of the non‐fluorescent small molecule 6‐mercaptopurine. This CRET process arose from a chemiluminescent (CL) donor–acceptor system in which the reaction of bis(2,4,6‐trichlorophenyl)oxalate (TCPO)–H₂O₂–fluorescein (maximum emission at 521.6 nm) served as the donor and gold nanoparticles (AuNPs, maximum absorption at 520.0 nm) served as the acceptor. This process caused a significant decrease in the CL signal of the TCPO–H₂O₂–fluorescein reaction. The presence of 6‐mercaptopurine induced an aggregation of AuNPs with the assistance of Cu²⁺ ions through cooperative metal–ligand interactions that was accompanied by a distinct change in color and optical properties. The maximum absorption band of the AuNPs was red‐shifted to 721.0 nm and no longer overlapped with the CL spectrum of the reaction; as a result, the CL signal was restored. This CRET system exhibited a wide linear range, from 9.0 nmol L^?1 to 18.0 μmol L^?1, and a low detection limit (0.62 nmol L^?1) for 6‐mercaptopurine. The applicability of the proposed CRET system was evaluated by analysis of 6‐mercaptopurine in spiked human plasma samples.     

Synthesis and Electrocatalytic Activity of 3Au?1Pd Alloy Nanoparticles/Graphene Composite for Bisphenol A Detection

In this study, a 3Au? 1Pd alloy nanoparticles/graphene composite (3Au? 1Pd alloy NPs/GN) with carboxyl groups and hydroxyl groups was prepared facilely by co‐reduction of graphene oxide (GO), HAuCl₄, K₂PdCl₄, with an Au? Pd alloy molar ratio of 3 : 1. The composite modified glass carbon electrode (GCE) showed a good performance for detecting bisphenol A (BPA) due to the enhanced electron transfer kinetics and large active surface area. The effective enrichment of BPA is attributed to the carboxyl groups and hydroxyl groups on the composite. According to the results of differential pulse voltammetry (DPV), the BPA oxidation current is linear to its concentration in the range of 10 nM–5.0 µM (R=0.998), and the detection limit is found to be 4.0 nM (S/N=3).     

Experimental investigation and thermodynamic prediction of the Al–Ge–Zn phase diagram

The knowledge of the phase diagram of the Al?CGe?CZn ternary system is of importance in the development of high temperature soldering materials. In this study, the phase diagram of the Al?CGe?CZn ternary system was calculated by the calculation of phase diagrams method using binary thermodynamic parameters included in the COST MP0602 thermodynamic database. Chosen alloys with compositions along two vertical sections with molar ratio Al/Ge?=?3/1 and 1/3 were measured using DTA (differential thermal analysis). The experimentally determined phase transition temperatures from this work and phase equilibria data from literature were compared with calculation results and good mutual agreement was noticed.     

Thermal conductivity of lightweight aggregate based on coal fly ash

The article presents the results of physical and chemical properties of lightweight aggregates (LWA) obtained by the thermal treatments of raw composition based on fly ash, supplied by electric plants from Serbia. The production process of LWA consists of raw material preparation, plastic shaping?Cextrusion, granulation, and thermal treatment at three temperatures: 1100, 1150, and 1200?°C. The final firing temperature (T?=?1150?°C) is chosen based on the mechanical and physical properties of the designed aggregates. The particle-size distribution of the LWAs is unimodal (d????16?mm) while the density value varies from 0.98 to 1.99?g/cm³. The water absorption values are determined by use of two methods: 24?h of soaking in cold water and 5?h of boiling. The thermal conductivity of unbound, fired LWA particles is determined by measuring the amount of axially transferred heat in the stationary state. The obtained value of the LWA thermal conductivity (???=?0.0872?W/mK, T?=?1150?°C) is suitable for the production of structural concrete blocks with improved thermal insulating properties. Because of their high-porosity and -compressive strength values, the designed LWA could be used instead of the conventional aggregates in the production of concrete blocks. Consequently, a real valorization of the waste material such as fly ash in Serbia was established.     

Calixarene-supported hexadysprosium cluster showing single molecule magnet behavior

The syntheses, crystal structures, magnetic and luminescent properties of three isomorphous compounds [Ln III 6 (μ 4-O) 2 (C4A) 2-(NO 3 ) 2 (HCOO) 2 (CH 3 O) 2 (DMF) 4 (CH 3 OH) 4 ] (Ln = Gd (1), Tb (2) and Dy (3); H 4 C4A = p-tert-butylcalix[4]arene) are reported. These three compounds are featured with the sandwich-like units constructed by two tail-to-tail calixarene molecules and an in-between Ln III 6 octahedron. The Dy III compound exhibits both single molecule magnet behavior and photoluminescence.     

Photofragment translational spectroscopy of ICl near 304 and 280 nm: Observation of an intense hot band effect

The photodissociation dynamics of ICl has been studied near 304 and 280 nm on a simple miniature time of flight (mini-TOF) photofragment translational spectrometer with a short pulse of a weak acceleration field. An intense hot band effect was observed. Many small peaks were resolved in each photofragment translational spectrum (PTS). Based on simulations, the principal peaks were assigned not only to the different photodissociation channels (1) I + Cl, (2) I + Cl*, (3) I* + Cl, or (4) I* + Cl*, but also to the different chlorine isotopes (35Cl and Cl). Moreover, some extra peaks showed the existence of an intense hot 37 band effect from vibrationally excited ICl molecules, though only a few percent of ICl molecules remained in the vibrationally excited states in our supersonic molecular beam. Based on the spectra near 304 nm, the quantum yield Ф of each channel, the curve crossing, and the branching fraction σ from each transition state were determined.     

双通道离子色谱法同步检测DOPO中的无机离子

以氯仿溶解9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO),离心取清液,自动进样器-双通道离子色谱法同步检测DOPO中的无机阴阳离子,采用自动进样器与双通道同步进行,大大缩短了分析时间,离子保留时间的相对标准偏差RSD(n=6)在0.07%～0.18%,峰面积的RSD(n=6)在0.43%～0.88%,重现性好。3种离子的平均回收率在94.87%～98.30%,结果令人满意。     

Synthesis,crystal structure and spectroscopic characterization of a hydrogen-bonded 1D copper(II) complex

Novel 1:2 and 1:1 (M:L) copper(II) complexes have been prepared from the tridentate ligand 2-(1-methyl-2-aza-5-oxapentyl)phenol (H₂L¹). The crystal structure of [Cu(HL¹)₂] (1) exhibits a noncentrosymmetric square-planar geometry with a slightly tetrahedral distortion. The Cu^II atom is coordinated by two amino N and two phenoxo O atoms of two (HL¹)^– ligands. The phenoxo and the alkoxy groups are involved in two strong intramolecular hydrogen bonds. The coordination moieties are further connected to a 1D linear structure by the action of intermolecular hydrogen bonds between the alkoxyl and the amino groups. The importance of steric hindrance introduced by the methyl group in the molecular structure and the packing of the complex molecules has been demonstrated. The e.p.r. parameters of (1) have been obtained: g = 2.231, g = 2.005, g _iso = 2.080, A = 185.0 G, A _iso = 86.5 G, A = (3A _iso – A )/2 = 37.3 G. These results confirm a distorted square planar stereochemistry with a ( )¹ ground state.