Orthogonal array design for the optimization of hollow fiber protected liquid-phase microextraction of salicylates from environmental waters

In the present study, a three phase-based hollow fiber protected liquid-phase microextraction (HF-LPME) method combined with high-performance liquid chromatography (HPLC) for the determination of salicylates in environmental waters was developed. The HF-LPME procedure was optimized by an L₁₆(4⁵) orthogonal array experimental design (OAD) with five factors at four levels. Under the optimal extraction condition (pHs of donor and receiving phases of 3.0 and 6.2, respectively, extraction time of 45 min, stirring speed of 1000 rpm, and salt addition of 20% (w/v)), salicylates could be determined in a linear range from 0.025 to 1.0 μg mL⁻¹ with a good correlation (r² > 0.9930). The limits of detection (LODs) ranged between 0.6 ng mL⁻¹ and 1.2 ng mL⁻¹ for the target analytes. The relative standard deviations (RSDs) of intra-day and inter-day were in the range of 0.64–14.58% and 0.16–15.45%, respectively. This procedure afforded a convenient, sensitive, accurate and cost-saving operation with high extraction efficiency for the model analytes. The method was applied satisfactorily to the determination of salicylates in two environmental waters.     

羟基化对Si3N4粉体水相分散性的影响

过施加硝酸有效地使氮化硅（Si₃N₄）粉末的表面羟基化,以改善在水性介质中的分散性。与天然粉末相比,羟基化粉末在水性介质中产生更稳定的胶体分散。傅里叶变换红外光谱和X射线光电子能谱结果表明,随着羟基改性,Si₃N₄粉末的羟基含量显著增加。这有助于防止Si₃N₄粉末在水性介质中聚集。此外,热重分析表明羟基化Si₃N₄粉末的羟基含量比天然粉末高68.8%。Si₃N₄粉末的表面亲水性通过羟基改性而增强,并且粉末分散性随着羟基含量的增加而提高。     

Research on Si-Al based catalysts prepared by complete liquid-phase method for DME synthesis in a slurry reactor

A series of Si-Al based DME synthesis catalysts were prepared by complete liquid-phase method and characterized by in situ XPS, XRD, N₂ adsorption and NH₃-TPD analyses. Based on the results, the addition of Si could adjust the pore structure and surface acidity of catalyst, exhibiting a strong promoting effect on the CO conversion and DME selectivity. However, when Si/Al ratio is higher, Si would cover active sites and increase the amount of strong acidity sites, causing the reduction in catalytic activity. It was found from in situ XPS characterization that Cu⁰ is the active center of methanol synthesis in DME production, and the addition of Si changes the chemical surroundings of active components and weaken the interaction between Cu, Zn and Al, which maybe give rise to the decrease in catalyst stability.     

Synthesis and Characterization of Diketopyrrolopyrrole-Based Aggregation-Induced Emission Nanoparticles for Bioimaging

Conventional fluorescent dyes have the property of decreasing fluorescence due to aggregation-caused quenching effects at high concentrations, whereas aggregation-induced emission dyes have the property of increasing fluorescence as they aggregate with each other. In this study, diketopyrrolopyrrole-based long-wavelength aggregation-induced emission dyes were used to prepare biocompatible nanoparticles suitable for bioimaging. Aggregation-induced emission nanoparticles with the best morphology and photoluminescence intensity were obtained through a fast, simple preparation method using an ultrasonicator. The optimally prepared nanoparticles from 3,6-bis(4-((E)-4-(bis(40-(1,2,2-triphenylvinyl)-[1,10-biphenyl]-4-yl)amino)styryl)phenyl)-2,5-dihexyl-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (DP-R2) with two functional groups having aggregation-induced emission properties and additional donating groups at the end of the triphenylamine groups were considered to have the greatest potential as a fluorescent probe for bioimaging. Furthermore, it was found that the tendency for aggregation-induced emission, which was apparent for the dye itself, became much more marked after the dyes were incorporated within nanoparticles. While the photoluminescence intensities of the dyes were observed to decrease rapidly over time, the prepared nanoparticles encapsulated within the biocompatible polymers maintained their initial optical properties very well. Lastly, when the cell viability test was conducted, excellent biocompatibility was demonstrated for each of the prepared nanoparticles.     

单滴液相微萃取-高效液相色谱法测定水中二甲戊乐灵农药残留

应用单滴液相微萃取(SD-LPME)技术建立了水体中二甲戊乐灵农药的高效液相色谱(HPLC)分析方法.研究了不同的萃取条件(萃取剂、体积、萃取时间、搅拌速度、温度等)及测定条件对检测二甲戊乐灵的影响,确定了最佳萃取条件:环己烷作萃取剂,萃取剂体积5 μL,液滴体积2 μL,搅拌速度350 r/min,35 ℃条件下萃取35 min.应用此方法测定了自来水和太湖水样中的二甲戊乐灵农药残留,相对标准偏差(RSD)在2 5%～3.4%(n=6)之间;回收率为88.0%～99.8%.     

Microwave—activated Coupling Reaction on Polyethylene Glycol

The two-step Sonogashira coupling reaction took place rapidly under microwave activation condition. PEG bound substrates acted as PTC and polymer support as well. Its yields are 80-90% and the products are in high purity.     

原位液相催化加氢法合成N-乙基苯胺和N，N-二乙基苯胺

以硝基苯为原料,Pt/γ-Al2O3为催化剂,乙醇水溶液为溶剂和氢供体,采用原位液相加氢一步法合成了N-乙基苯胺和N,N-二乙基苯胺.采用低温N2吸附-脱附、电感耦合等离子体发射光谱、X射线衍射、程序升温化学吸附和透射电子显微镜等对Pt/γ-Al2O3催化剂进行了表征,并考察了所制备催化剂的原位液相加氢性能.结果表明,在温度为503K、压力为5.0MPa、空速为3.2h-1、溶剂水含量为30%以及硝基苯浓度为8%的反应条件下,在Pt/γ-Al2O3催化剂上原位液相加氢合成N-乙基苯胺及N,N-二乙基苯胺有较好的结果,硝基苯转化率达到100%,N-乙基苯胺和N,N-二乙基苯胺的总收率达到99.5%.讨论了硝基苯原位液相加氢合成N-乙基苯胺和N,N-二乙基苯胺的反应机理.     

Liquid–liquid phase equilibrium in ternary immiscible Al–Bi–Sn melts

In this paper, the liquid-phase separation of ternary immiscible Al–Bi–Sn melts was studied with resistivity and thermal analysis methods at different temperatures. The resistivity–temperature curves appear anomalous and abrupt change as rising temperature, corresponding to the distinctive and low peak of melting process in the differential scanning calorimetry (DSC) curves, indicative of the occurrence of the liquid-phase separation. The anomalous behaviour of the resistivity temperature dependence is attributable to concentration–concentration fluctuations. The microheterogeneity–microhomogeneity transformation causes large fluctuations in concentration, which make the randomness and chaos of the atoms larger, leading to the greater impediment to electron movement and the sharp rise of resistivity. The addition of tin to the Al–Bi immiscible alloys decreases the monotectic reaction. It is concluded that concentration–concentration fluctuations are responsible for the anomalous behaviour of resistivity and DSC methods.     

In-drop derivatisation liquid-phase microextraction assisted by ion-pairing transfer for the gas chromatographic determination of phenolic endocrine disruptors

A novel in-drop derivatisation liquid-phase microextraction procedure with an ion-pairing agent is developed and optimised for the extraction of endocrine-disrupting chemicals. The ethyl esters of the analytes were rapidly formed in the organic drop and analysed by gas chromatography. The effects of various parameters such as rate and time of agitation, ion-pairing agent and reactant concentration, pH and temperature were studied systematically to optimise the process and bring out the locale of reaction in the organic drop. A study of the mechanistic pathways of the overall procedure is attempted leading to interesting findings and delineating important points of the kinetics and mechanism. A mechanistic model is proposed on the basis of the theory of mass transfer with chemical reaction in two liquid phases. The O-ethoxycarbonyl derivatisation appears to take place in the bulk organic phase. The system provides insight into the first reported analytical case of single-drop extraction-preconcentration-derivatisation assisted by an ion-pairing transfer and has all of the interesting facets of chemical reaction in which the role of mass transfer comes into picture.The analytical features of the method are acceptable and the overall relative standard deviations of the intra-day repeatability (n = 5) and inter-day reproducibility were <3.9% and <5.4%, respectively, for gas chromatography-mass spectrometry analyses and <4.3% and <7.1% for gas chromatography-flame ionisation detection analyses. The method was applicable to urine and surface water samples. The LODs ranged between 0.2-1.3 ng mL⁻¹ and 8.5-26.5 ng mL⁻¹ for GC/MS and GC/FID analyses, respectively.     

Pyridine-based Liquid-Phase Synthesis of Crystalline TiN and ZnSiN2 Nanoparticles

TiN and ZnSiN₂ nanoparticles are obtained via a novel pyridine-based synthesis route. This one-pot liquid-phase route strictly avoids all oxygen sources (including starting materials, surface functionalization, solvents), which is highly relevant in regard of the material purity and material properties. Colloidally stable suspensions of crystalline, small-sized TiN (5.4±0.4 nm) and ZnSiN₂ (5.2±1.1 nm) are instantaneously available from the liquid phase. Elemental analysis and electron energy loss spectroscopy confirm the purity of the compounds and specifically the absence of oxygen. The as-prepared ZnSiN₂ show yellowish emission (500-700 nm) already at room temperature with its maximum at 570 nm.