Free radical SH2′ reaction mechanism study by comparing free radical SH2′ reaction with free radical addition reaction

It is not clear whether the mechanism of the S_H2′ reaction of allyl chloride is concerted or stepwise. The relative rates of the competitive free radical addition to two different double bonds in (2-chloroallyl)-(2-choromethylallyl) ether have been determined. There are two competitive free radical addition reactions, one is free radical S_H2′ reaction and the other is free radical addition reaction. The mechanism of the S_H2′ reaction is discussed by comparing free radical S_H2′ reaction with free radical addition reaction.     

激光对火焰的诊断Ⅱ. 激光诱导荧光法对液化石油气/空气火焰中的OH基浓度二维分布的检测

通过部份预混的富燃料液化石油气/空气火焰中各部份的OH(A~(2∑~+)←→X ~(2Π))的激光诱导荧光信号进行逐点检测, 获得了OH(X)基在火焰中央纵剖面上精细的二维等浓度线图。OH(X)在外焰边缘上分布最浓, 是自内向外扩散的H原子与O原子相遇而引起反应的结果。同时一部份OH(A)基的生成, 发出了紫外的A→X化学发光, 形成了外焰的轮廓。     

Behaviour of series piezoelectric sensor in electrolyte solution : Part II. Applications in titrimetry

The applications of a series piezoelectric sensor for end-point determination in frequencimetric titrations, including neutralization, precipitation, complexation and redox titrations, are reported. The method is based on the fact that a series piezoelectric sensor shows a sensitive and selective frequency response to changes in conductivity of solution and can be applied to sample solutions containing large amounts of unreacted foreign electrolytes.     

Intramolecular π–π stacking in diaquabis(2‐hydroxybenzoato‐κO)bis(1,10‐phenanthroline‐κ2N,N′)strontium(II)

In the title compound, [Sr(C₇H₅O₃)₂(C₁₂H₈N₂)₂(H₂O)₂], the Sr^II ion is located on a twofold rotation axis and assumes a distorted square‐antiprism SrN₄O₄ coordination geometry, formed by two phenanthroline (phen) ligands, two 2‐hydroxybenzoate anions and two water molecules. Within the mononuclear complex molecule, intramolecular π–π stacking is observed between nearly parallel coordinated phen ligands, while normal intermolecular π–π stacking occurs between parallel phen ligands of adjacent complex molecules. Classic O—H...O and weak C—H...O hydrogen bonding helps to stabilize the crystal structure.     

废旧镍镉电池真空蒸馏规律的研究

在实验室条件下，对镍镉电池的真空蒸馏基本规律进行了探索.分析了温度、压力和时间等工艺因素对镍镉分离效果的影响，并对镍镉电池的真空蒸馏机理进行了研究，为废旧镍镉电池资源化提供了理论依据和实验数据.     

A conductance sensor for dissolved sulphur dioxide using a series piezoelectric crystal device

A new piezoelectric crystal impedance sensor for the determination of sulphur dioxide in aqueous solution is presented. It is realized using a series piezoelectric crystal device which is constructed by connecting an AT-cut piezoelectric crystal to a probe in series. The probe is filled with an internal electrolyte solution that is separated from sample solutions by a gas-permeable membrane. The present sensor exhibits a favourable frequency response to 1 x 10(-7)-1 x 10(-3) M sulphur dioxide. The detection limit is 1 x 10(-8) M. The effects of the sensor preparation are considered. Dynamic range, reproducibility, response time and selectivity of the sensor are also discussed. The proposed sensor has been used successfully for lamp sulphur determinations in petroleum samples.     

1,5-二氮杂双环[4,3,0]壬碳-5-烯与全氟炔酸酯的反应及其产物的核磁共振研究

1，5—二氮杂双环[4，3，0]壬碳—5—烯(DBN)与全氟炔酸酯反应生成成环化合物。通过对成环产物的^1HNMR、^13C NMR及相关的2D NMR谱的分析，确证了该类化合物的结构，并讨论了其化学位移及J-偶合特征。同时提出了整个反应可能的历程和机理。     

Polymer particles with various shapes and morphologies produced in continuous microfluidic reactors

We report a novel approach to continuous and scalable production of core-shell droplets and polymer capsules in microfluidic devices. The described method is also useful in the synthesis of polymer particles with nonspherical shapes. We used capillary instability-driven break-up of a liquid jet formed by two immiscible fluids. Precise control of emulsification of each liquid allowed for the production of highly monodisperse core-shell droplets with a predetermined diameter of cores and thickness of shells. We also achieved control over the number of cores per droplet and the location of cores in the droplet. We carried out fast throughput photopolymerization of the monomeric shells and obtained polymer particles with various shapes and morphologies, including spheres, truncated spheres and, hemispheres, and single and multicore capsules.     

Continuous microfluidic reactors for polymer particles

This article provides an overview of our work in the area of the synthesis of polymer particles in continuous microfluidic reactors. The method includes (a) the generation of highly monodisperse monomer droplets in a microfluidic flow-focusing device and (b) in-situ solidification of these droplets by means of photopolymerization. We discuss the effect of monomer properties on the emulsification process, the effect of the polymerization rate on the production of high-quality particles, the role of the material of the microfluidic device in droplet formation, and the synthesis of particles with different shapes and compositions. We also demonstrate the production of highly ordered arrays of polymer particles achieved by photopolymerization of the dynamic lattices of monomer droplets in microfluidic channels. The article is concluded with a summary of future research directions in the production of polymer colloids in microfluidic reactors.     

Bulk acoustic wave sensor using molecularly imprinted polymers as recognition elements for the determination of pyrimethamine

A new bulk acoustic wave (BAW) sensor modified with a molecularly imprinted polymer (MIP) was fabricated and applied for the determination of pyrimethamine. This sensor exhibited high selectivity and sensitive response to pyrimethamine. Factors such as pH and the amount of coating influencing sensor properties, were investigated in detail and optimized. The calibration curve was linear in the range 6.0x10(-7)-1.0x10(-4) M. The determination limit was 2.0x10(-7) M. In harsh chemical environments such as high temperature, organic solvents, bases, acids, etc., the sensor still exhibited long-term stability. The proposed method has been satisfactorily applied for the determination of pyrimethamine in serum and urine media.