Voltammetric Behavior of the Alizarin Red S Interaction with DNA and Damage to DNA

The electrochemical behavior and the interaction of alizarin red S (ARS) with calf thymus DNA was investigated on a bare glassy carbon electrode (GCE) and DNA modified GCE (DNA/GCE), respectively. ARS showed a pair of redox peaks at ?0.445 V and ?0.414 V on a bare GCE. On addition of DNA into the ARS solution, the peak current of ARS decreased and the peak potential positively shifted, but without new redox peaks appeared. The ARS reduction peak current increased with immersion time on a DNA/GCE. The results showed that ARS could interact with DNA molecules by intercalative binding mode. The equilibrium constant, binding number and the ratio of binding constant for oxidized and reduced ARS forms were obtained. The DNA damage was directly detected by appearance of guanosine and adenosine bases oxidation signal. The influence of experimental conditions on DNA damage extent was discussed in detail.     

阳离子交换柱分离-导数光度法测定原油中钒

以 5Br PADAP为显色剂 ,用阳离子交换柱分离干扰离子 ,在波长 6 30nm采用一阶导数光度法测定原油中钒 ,方法灵敏度高 ,摩尔吸光系数为 3.0× 10 5L·mol- 1·cm- 1,较其它光度法测定钒的摩尔吸光系数提高 1～ 2个数量级。对实际样品进行分析并做加标回收试验 ,钒的回收率在97.5 %～ 10 4 .0 %。与ICP AES方法进行对照试验 ,结果相吻合。     

千克级窄分子质量分布聚苯乙烯的制备与表征

以正丁基锂为引发剂，以经过处理的工业级环己烷为溶剂、四氢呋喃为促进剂，用阴离子聚合的方法，在常压和惰性气体保护条件下，制得一系列千克级窄分子质量分布的聚苯乙烯，利用IR、^1H-NMR、GPC等技术对聚苯乙烯产物进行了表征，分析了影响聚苯乙烯的分子质量及分子质量分布的因素。     

Analysis of Petroleum Distillates from Fire Debris Using Supercritical Fluid Extraction with a Two‐Level Orthogonal Array Experimental Design

A supercritical fluid extraction (SFE) method was developed in the present study as an effective sample pretreatment technique of petroleum distillates from fire debris. Three petroleum distillates were used as target analytes, including 95 unleaded gasoline, kerosene, and premium diesel. An orthogonal array (L16) experimental design was adopted to separately evaluate primary SFE experimental factors. The SFE efficiencies of petroleum distillates at various extraction conditions were examined and the optimized SFE conditions were identified. Experimental results demonstrated that the optimized SFE method not only provided an effective extraction method for the spiked sample, but also successfully recovered residues of petroleum distillates from fire debris.     

Mechanism of coupling reactions of polystyryllithium with dihalomethanes

We report here an in‐depth analysis of the reaction mechanisms involved in the formation of polymer dimers formed by the coupling of polystyryllithium (PSLi) with dichloromethane (DCM), dibromomethane (DBM), and diiodomethane (DIM) in tetrahydrofuran at ?78 °C. The DBM‐mediated reactions give a high degree of coupling but generate 1,2‐diphenyl linkages in addition to the expected 1,3‐diphenyl linkages and small amounts of β‐substituted styrenic end groups that are detectable by fluorescence measurements. This is consistent with the formation of bromobenzyl end groups by lithium–bromine exchange and PSLi‐mediated elimination. The formation of α‐substituted styrenic end groups by conventional displacement and elimination is also possible. Although reactions of PSLi with DCM show no coupling at all, DIM is a much better coupling agent than DBM, significantly suppressing side reactions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1081–1091, 2002     

d‐Secoestrone derivatives. VI. 17β‐Benzyl‐17α‐hydroxy‐3‐methoxyestra‐1,3,5(10)‐trien‐16‐one

The title mol­ecule, C₂₆H₃₀O₃, shows a novel chemical rearrangement of the substituents at position 17, i.e. an α‐­orientation of the hydroxy group and a β‐orientation of the bulky benzyl moiety. The packing arrangement consists of coils formed by O2?O3 hydrogen bonds along the c axis. The compound shows complete loss of oestrogenic activity, and neither does it exhibit an antagonistic effect.     

Ruthenium‐catalyzed formal alkyl group transfer: Synthesis of quinolines from nitroarenes and alkylammonium halides

Nitroarenes are reductively cyclized with an array of tetraalkylammonium halides and trialkylarnmonium chlorides in the presence of a catalytic amount of a ruthenium catalyst along with tin(II) chloride dihydrate at 180° to afford the corresponding quinolines in moderate to good yields. The addition of tin(II) chloride dihydrate is necessary for the effective formation of quinolines and toluene is the solvent of choice. A reaction pathway involving initial reduction of nitroarenes to anilines and conversion of alkylammonium halides to alkylamines, alkyl group transfer from alkylamines to anilines to form an imine, dimerization of imine, and heteroannulation is proposed for this catalytic process.     

Interplay of Electronic Structure and Bulk Properties in 2D and 3D Ternary Carbonitrides from First Principles

The changes in electronic structure and hardness as inferred from the bulk modulus are investigated for model structures of ternary compounds XC₃N₃ (X = B, Al, P, As, Ga) within the framework of density functional theory (DFT). The optimisations of the proposed two‐ (2D) and three‐dimensional (3D) structures and the calculations of the bulk moduli are performed by a pseudo potential method. The electronic structures are calculated with the augmented sphere wave method (ASW). The obtained hardness for 2D BC₃N₃ system (B₀ ～ 220 GPa) points to a magnitude close to that of graphitic C₃N₄. For heavier X atoms it decreases rapidly. This is equally observed for the 3D systems examined in the β‐C₃N₄ structure for which B₀(β‐BC₃N₃) amounts to ～330 GPa. Within the magnitude of the well known hard material cubic BN, the BC₃N₃ phases can be predicted as candidates for ultra hard materials. The electronic effect induced by the chemical nature of the X substitutional was examined according to its position in the periodic table i.e. X_III or X_V. Both, band structures and the electron localisation function (ELF) were used for this analysis. The ELF plots show a decreasing covalency with heavier X‐atoms. Potential applications of the devised systems are proposed such as dopings with atoms (Li, rare gas) and molecules (N₂).     

Synthesis of perfluoroalkyl-containing multifunctional groups compounds for textile finishing

A new kind of perfluoroalkyl-containing multifunctional groups compound was designed. Treatment of 1H,1H,2H,2H-perfluorooctyltrichlorosilane (4) with allylmagnesium bromide provided key intermediate 1H,1H,2H,2H-perfluorooctyltriallylsilane (2). Hydroboration followed by oxidation, epoxidation and dihydroxylation of 2 gave perfluoroalkyl-containing multifunctional groups compound 1a, 1b and 1c, respectively.     

(m‐CH3C6H4NH3)6P6O18

In hexakis(m‐toluidinium) cyclo­hexaphosphate, 6C₇H₁₀N⁺·­P₆O₁₈^6?, the atomic arrangement is typical of a layer structure. Layers including the centrosymmetric P₆O₁₈ ring anions develop around the (100) planes at x = . The hydrogen‐bond distribution is described.