Determination of UV filters in river water samples by in‐line SPE‐CE‐MS

The use of SPE coupled in‐line to CE using electrospray MS detection (in‐line SPE‐CE‐ESI‐MS) was investigated for the preconcentration and separation of four UV filters: benzophenone‐3, 2,2‐dihydroxy‐4‐methoxybenzophenone, 2,4‐dihydroxybenzophenone and 2‐phenylbenzimidazole‐5‐sulphonic acid. First, a CE‐ESI‐MS method was developed and validated using standard samples, obtaining LODs between 0.06 μg/mL and 0.40 μg/mL. For the in‐line SPE‐CE‐ESI‐MS method, three different sorbents were evaluated and compared: Oasis HLB, Oasis MCX, and Oasis MAX. For each sorbent, the main parameters affecting the preconcentration performance, such as sample pH, volume, and composition of the elution plug, and sample injection time were studied. The Oasis MCX sorbent showed the best performance and was used to validate the in‐line SPE‐CE‐ESI‐MS methodology. The LODs reached for standard samples were in the range between 0.01 and 0.05 ng/mL with good reproducibility and the developed strategy provided sensitivity enhancement factors between 3400‐fold and 34 000‐fold. The applicability of the developed methodology was demonstrated by the analysis of UV filters in river water samples.     

Continuous Spectroscopy Characterization of Emulsions

In emulsion polymerization, the formation of particles has an important effect on the rate of reaction and on the final properties of the latex. To investigate particle nucleation mechanisms in emulsion polymerization it is necessary to establish the initial conditions of the emulsified system before the reaction takes place. This research reports on a technique to continuously monitor the droplet size distribution of liquid-liquid emulsions using spectroscopy. The on-line particle characterization methodology is based on an integrated sampling and dilution strategy combined with spectroscopy methods. It is shown that the sampling system integrated with a multiwavelength turbidity detector provides reliable estimates of droplet populations as function of the dispersed phase concentration in emulsions of saturated hydrocarbons. The results provide not only the groundwork necessary for the elucidation of particle nucleation during emulsion polymerization process but also suggests the potential of this combined technology to further our understanding of liquid-liquid emulsions.     

Nuclear quantum effect and temperature dependency on the hydrogen‐bonded structure of base pairs

The structure of Watson–Crick‐type adenine‐thymine and guanine‐cytosine pairs has been studied by hybrid Monte Carlo (HMC) and path integral hybrid Monte Carlo (PIHMC) simulations with the use of semiempirical PM6‐DH+ method in the gas phase. We elucidated the nuclear quantum effect and temperature dependency on the hydrogen‐bonded moiety of base pairs. It was shown that the contribution of nuclear quantum effect on the hydrogen‐bonded structure is significant not only at low temperature 150 K but also at temperature as high as 450 K. The relative position of hydrogen‐bonded proton between two heavy atoms and the nuclear quantum nature of the proton are also shown. Furthermore, we have applied principal component analysis to HMC and PIHMC simulations to analyze the nuclear quantum effect on intermolecular motions. We found that the ratio of Buckle mode (lowest vibrational mode from normal mode analysis) decreases due to the nuclear quantum effect, whereas that of Propeller mode (second lowest vibrational mode) increases. In addition, nonplanar structures of base pairs were found to become stable due to the nuclear quantum effect from two‐dimensional free energy landscape along Buckle and Propeller modes. © 2013 Wiley Periodicals, Inc.     

Structure and spectroscopic aspects of water‐halide ion clusters: A study based on a conjunction of stochastic and quantum chemical methods

In this article, we propose a stochastic search based method, namely genetic algorithm in conjunction with density functional theory to evaluate structures of water‐halide microclusters, with the halide ion being Cl^?, Br^?, and I^?. Once the structures are established, we evaluate the infrared spectroscopic modes, vertical detachment energies and natural population analysis based charges. We compare our results with available experimental and theoretical results. © 2012 Wiley Periodicals, Inc.     

A New Coordination Polymer Containing 4-[（8-Hydroxy-5-quinolinyl）azo]-benzenesulfonic Acid： Synthesis,Structure and Fluorescent Property

A new coordination polymer, {[CdL（en）]＇DMF}n （1, H2L = 4-[（8-hydroxy-5- quinolinyl）azo]-benzenesulfonic acid, en = ethylenediamine, DMF = N,N-dimethylformamide）, has been solvothermally synthesized and structurally characterized by single-crystal X-ray diffrac- tion, infrared （IR） spectra, elemental analysis, powder X-ray diffractions （PXRD） and thermo- gravimetric analysis （TGA）. Compound 1 crystallizes in monoclinic, space group P2Jc with a = 14.6525（9）, b = 13.3917（9）, c = 11.8838（8） A, β = 101.2290（10）°, V = 2287.2（3） A3, Z = 4, C20H24CdN6OsS, Mr = 572.91, Dc. = 1.664 mg-mm-3, F（000） = 1160, p = 1.091 mm-1, R = 0.0232 and wR = 0.0587 for 3597 observed reflections （I 〉 2σ（I））. Compound 1 exhibits a one-dimensional （1D） double-chain structure which is further connected through hydrogen bonding and π-π interactions into a three-dimensional （3D） supramolecular network. In addition, it exhibits blue fluorescence at room temperature in the solid state.     

Halonickel 2,4-di-t-butyl-6-(quinolin-8-yliminomethyl)phenolates: Synthesis, characterization and ethylene reactivity

A series of nickel halides bearing 2,4-di-t-butyl-6-(quinolin-8-yliminomethyl) phenolate ligands was synthesized and characterized by IR spectroscopy and elemental analysis.Molecular structures of C1(R = H,X = Br) and C2(R = H,X = Cl) were further confirmed by single-crystal X-ray crystallographic studies,and revealed a distorted square planar geometry at nickel.Upon activation with diethylaluminum chloride(Et 2 AlCl),all nickel pre-catalysts displayed good catalytic activity [up to 9.3 × 10 5 g mol 1(Ni) h 1 ] for ethylene oligomerization with major dimerization.In the presence of methylaluminoxane(MAO),the nickel complex C1 was capable of ethylene polymerization under 3 MPa,and produced polyethylene products with narrow polydispersity(1.16 1.73) and molecular weights in the range of 2.6 4.95 kg/mol.     

EDTA对活性炭的功能化处理及其对炭载Pd催化剂电催化性能的影响

采用乙二胺四乙酸(EDTA)对活性炭进行功能化处理, 研究了其对表面基团、炭载Pd 纳米粒子结构及Pd催化剂电催化性能的影响. 傅里叶变换红外(FTIR)光谱和X射线光电子能谱(XPS)表征表明, EDTA处理在炭表面引入了含氮基团. X射线粉末衍射(XRD)光谱、透射电镜(TEM)和电化学测试结果显示, 活性炭经EDTA处理后, 负载的Pd粒子粒径虽有所增大, 但由于炭载体与Pd粒子相互作用的增强, Pd利用率增加, 催化剂对甲酸氧化的活性和稳定性均显著提高. 电化学阻抗谱(EIS)分析进一步揭示, 甲酸在该催化剂电极上的电氧化反应具有较低的电荷传递电阻.     

两个4-[(8-羟基-5-喹啉)偶氮]苯磺酸配合物的合成、结构及性质研究

以4-[(8-羟基-5-喹啉)偶氮]苯磺酸(H₂L)为配体,采用溶剂热合成法合成了两个配合物[CuL(en)]·0.5H₂O (1)和[CuL₂][Cu(en)₂]·2H₂O (2)(en=乙二胺),并采用单晶X-射线衍射、红外光谱、元素分析、X-射线粉末衍射和热重分析对其进行表征。化合物1和2通过氢键和π…π相互作用连接形成了三维超分子网格。此外,还研究了两个化合物的荧光性质。     

LABVIEW下冲击试验测试信号分析模块的设计

根据GJB冲击环境试验测试要求,介绍LABVIEW平台下两类典型冲击信号分析模块的设计方法,主要讲述利用多图层叠加编程技术实现GJB150.18-1986标准规定的半正弦波与后峰锯齿波动态套容差曲线分析模块的设计以及利用递归算法实现冲击响应谱分析模块的设计。其次,采用资源DLL封装技术对LABVIEW编程实现的冲击信号分析模块进行封装,在其他编程语言中调用DLL实现冲击信号分析模块在其他编程语言中的功能链接。实践表明,LABVIEW图形化编程技术可快速实现两类冲击信号分析模块的设计,将高速数据采集模块与冲击信号分析模块集成,可有效完成冲击试验测试与信号分析处理任务。