Effect of crystallinity on electrical properties of electron beam irradiated LDPE and HDPE

Two sets of low-density polyethylene (LDPE) and high-density polyethylene (HDPE) sheets were prepared using warm press system. Each set consisted of three subsets which were made in different cooling rate procedures: fast cooling with cassette; exposing in open air; and exposing in 0 °C water, to investigate the crystallinity effects. The samples were irradiated with 10 MeV electron beam in the dose range of 0–370 kGy using a Rhodotron accelerator system. The variation of electrical properties of all samples such as breakdown voltage, surface and volume resistivity were measured and graphed against the dose values. The radiation induced cross-linking and cooling procedure effects were investigated and compared in the obtained results.     

Silica Sulfuric Acid/Sodium Dichromate Dihydrate as an Efficient Heterogeneous Method for the Oxidation of Alcohols Under Mild Conditions

A combination of silica sulfuric acid and sodium dichromate dihydrate in the presence of wet SiO 2 were used as an effective oxidizing agent for the oxidation of alcohols to their corresponding aldehyde or ketone derivatives in dichloromethane or toluene with excellent yields.     

苯并噻唑和铁氧化物纳米粒子修饰的磁性棒碳糊电极上肼的电催化氧化反应：同时检测肼和苯酚

开发了一种磁性Fe3O4纳米粒子和2-(3,4-二羟苯基)苯并噻唑(DPB)修饰的磁性棒碳糊电极(MBCPE)用于电化学检测肼.首先将DPB自组装在Fe3O4纳米粒子上,然后将此复合物吸附于设计的MBCPE上. MBCPE电极将磁性纳米粒子吸引到电极表面.所得新型电极具有高的导电性和大的有效比表面积,因而对肼的电催化氧化反应有非常大的电流响应.采用伏安法、扫描电镜、电化学阻抗谱、红外光谱和紫外-可见光谱对修饰电极进行了表征.采用伏安法研究了在磷酸盐缓冲溶液(pH=7.0)中MBCPE/Fe3O4NPs/DPB电极上肼的电化学行为.作为电化学传感器, MBCPE/Fe3O4NPs/DPB电极对肼氧化反应表现出极高的电催化活性.在DPB存在下,肼的氧化电势下降,但其催化电流增加.电催化电流与肼浓度在0.1–0.4和0.7–12.0μmol/L二个区间内表现出线性关系,检测限为18.0 nmol/L.另外,研究了MBCPE/Fe3O4NPs/DPB电极同时检测肼和苯酚的性能.伏安实验结果显示,苯酚的线性区域为100–470μmol/L,检测限为24.3μmol/L.采用此电极检测了水样品中的肼和苯酚.     

The use of Nafion-H®/NaNO2 as an efficient procedure for the chemoselective N-nitrosation of secondary amines under mild and heterogeneous conditions

A combination of Nafion-H® and sodium nitrite in the presence of wet SiO₂ was used as an effective agent for the N-nitrosation of secondary amines under mild and heterogeneous conditions in good to excellent yields.     

Selective and Simultaneous Voltammetric Determination of Glutathione,Uric Acid and Penicillamine by a Modified Carbon Nanotube Paste Electrode

In this paper, the use of a carbon paste electrode (CPE) modified by (E)‐3‐((2‐(2,4‐dinitrophenyl)hydrazono)methyl)benzene‐1,2‐diol (DHB) and carbon nanotubes (CNTs) for the determination of glutathione (GSH), uric acid (UA) and penicillamine (PA) is described. Initially, cyclic voltammetry was used to investigate the redox properties of the modified electrode in phosphate buffer. Next, the electrocatalytic oxidation of GSH via EC′ mechanism at the modified electrode was described. At the optimum pH of 7.0, the oxidation of GSH occurs at a potential that is 530 mV less positive than that of an unmodified carbon paste electrode. The values of the diffusion coefficient (D=2.5×10^?6 cm² s^?1) and the catalytic rate constant (k=1.7×10³ M^?1 s^?1) were calculated for GSH, using chronoamperometry. Based on differential pulse voltammetry, the oxidation of GSH exhibited a dynamic range between 0.4 and 700.0 µM and a detection limit (3σ) of 70.0 nM. Also, simultaneous determination of GSH, UA and PA was described at the modified electrode. Finally, this method was used for the determination of these substances in synthetic solutions and blood serum samples.     

The use of silica sulfuric acid as an efficient catalyst for deprotection of trimethylsilyl ethers to the corresponding alcohols under mild and heterogeneous conditions

Silica sulfuric acid was used as a suitable catalyst for the conversion of trimethylsilyl ethers to the corresponding alcohols in the presence of wet SiO2 in high yields at room temperature.     

Chemoselective synthesis of 1,1-diacetates from aldehydes in the presence of Al(HSO<Subscript>4</Subscript>)<Subscript>3</Subscript> under mild solvent-free conditions

A novel efficient procedure has been developed for the preparation of acylals in high yields by reaction of the corresponding aldehydes with acetic anhydride in the presence of Al(HSO₄)₃ as catalyst under mild (room temperature) solvent-free conditions. Published in Russian in Zhurnal Organicheskoi Khimii, 2007, Vol. 43, No. 6. pp. 855–857. The text was submitted by the authors in English.