Investigations of surface degradation of high‐density polyethylene materials resulting from tracking,using physicochemical analysis

In the present work tracking phenomena were studied with high‐density polyethylene (HDPE) materials under dc voltage, with NH₄Cl and acid rain as contaminants. It was determined that the tracking time of the material depends on the conductivity and flow rate of the contaminant. Furthermore, physicochemical analysis by wide‐angle X‐ray diffraction studies, differential scanning calorimetry, and luminescence spectroscopy was carried out, whereupon it was concluded that the tracking process is a surface‐degradation process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2843–2849, 2002; DOI 10.1002/app.10260     

Cuticular hydrocarbons ofReticulitermes virginicus (Banks) and their role as potential species- and caste-recognition cues

The cuticular hydrocarbon components of four castes ofReticulitermes virginicus (Banks) have been identified and quantitated. Components identified includen-alkanes; 2-, 3-, 11-, 13-, and 15-methyl-alkanes; 11,15-dimethylalkanes, (Z)-9-alkenes; (Z,Z)-7,9-dienes; and (E/Z)-6,9-dienes ranging in carbon number from C₂₁ to C₄₀. All caste forms ofR.virginicus contained the same components, but showed caste-specific proportions. Comparison of these hydrocarbons with those of the sympatric termiteR. flavipes (Kollar) suggest that cuticular hydrocarbons might serve as species- and caste-recognition cues. A bioassay was developed to test this species-recognition hypothesis, with the experimental results supporting the hypothesis.Isoptera: Rhinotermitidae.     

Cuticular lipids of the booklouse,Liposcelis bostrychophila: hydrocarbons,aldehydes, fatty acids,and fatty acid amides

The booklouse, Liposcelis bostrychophila, is an increasingly common pest of stored food products worldwide. We report here the cuticular lipid composition of this pest (the first report of the hydrocarbons of any member of the Order Psocoptera and the first report of fatty acid amides as cuticular components for any insect). No unsaturated hydrocarbons were present. A homologous series of n-alkanes (C₂₁–C₃₄), monomethyl alkanes (3-, 4-, 5-, 7-, 9-, 11-, 12-, 13- and 15-methyl-) with a carbon chain range of C₂₈–C₄₂, and dimethyl alkanes (3, 7-; 9, 13-; 11, 15-; 13, 17-; 9, 21-; 11, 19-; and 13, 21-); with a carbon number range of C₃₁–C₄₃ were identified. The relative abundances of these hydrocarbons were low, comprising approximately 0.0125% of total biomass. The amides were a homologous series (C₁₆–C₂₂ in chain length), with the major amide being stearoyl amide. In addition to the amides, free fatty acids (C_16:1, C_16:0, C_18:2, C_18:1, and C_18:0 in chain length) and three straight chain aldehydes (C₁₅, C₁₆, and C_17:1 in chain length) also occurred as cuticular components. These findings are discussed in terms of the chemical and physiological ecology of this species.     

Electrochemical copolymerization of aniline with m-aminophenol and novel electrical properties of the copolymer in the wide pH range

A copolymer, poly(aniline-co-m-aminophenol), has been synthesized using repeated potential cycling. The monomer concentration ratio, acid concentration and applied potential strongly affect the copolymerization rate and the properties of the copolymer. The optimum conditions for the copolymerization are that the scan potential range is controlled between −0.10 and 0.95 V (vs.SCE), and a solution consists of 0.34 M aniline, 0.012 M m-aminophenol and 2 M H₂SO₄. The IR spectra of the copolymers demonstrate that the m-aminophenol units are included in the copolymer chains. The cyclic voltammograms of the copolymers in 0.3 M Na₂SO₄ solution with various pH values were performed at the potential ranges from −0.20 to 0.80 V and at a scan rate of 60 mV s⁻¹. The results indicate that the copolymer still hold 41.7% of the electrochemical activity when the copolymer electrode was transferred from a solution of pH 5.0 to a solution of pH 11.0 in the potential range of −0.20 to 0.80 V. An impedance plot of the copolymer in a solution with pH 12.0 and at 0.40 V is constructed of a semicircle and a Warburg line with a slope of 1. This means that the electrode reaction of the copolymer at pH 12.0 is also under mass transfer control. The conductivity of the copolymer prepared under the optimum conditions is 1.42 S cm⁻¹, and slightly depends on the pH value. Thus, the pH dependence of the electrical properties of the copolymer is improved compared with poly(aniline-co-o-aminophenol), and is much better than that of the parent polyaniline.     

meso－苯基四苯并卟啉的合成和光谱性能研究（Ⅱ）

本文将ｍｅｓｏ－苯基四苯并卟啉锌（Ｚｎ－Ｐ_ｎＴＢＰｎ＝１～４）在酸性条件下脱锌，获得了不含金属离子的ｍｅｓｏ－苯基四苯并卟啉（Ｈ_２Ｐ_ｎＴＢＰｎ＝１～４）。研究了它们的吸收光谱、荧光光谱及在溶液状态下的瞬态光谱特性，并对照相应的锌卟啉，讨论了两者之间的光谱差异。     

若干激光基质材料的晶纤生长及荧光性能

制备了以ZrO_2,Gd_2O_2,LiNbO_3或YAG为基质,具有不同掺杂离子的12个单晶纤维试样,还测量了这些试样的化学成份及荧光光谱。     

Reductive alkylation of illinois No. 6 coal. 1H and 13C n.m.r. spectra of the 13C-enriched alkylation products

The reductive alkylation of Illinois No. 6 coal has been carried out using potassium and naphthalene in tetrahydrofuran and methyl-¹³C and butyl-1 -¹³C iodides to alkylate the resultant polyanion. The soluble products of the reductive alkylation reaction were isolated by extraction and chromatography. Proton and carbon n.m.r. spectra were recorded. The intense resonance signal at δ3.95 which appears in the proton n.m.r. spectra of Illinois No. 6 coal butylated with unenriched butyl iodide is split into a doublet by the ¹³C nuclei. Similar results were obtained for the methylation products. The chemical shift and coupling interaction establish that aryl ethers are a very important constituent of the alkylated coal. The carbon n.m.r. spectra of the coal alkylated with ¹³C-enriched alkyl iodides are intense. The resonances of the C-alkylation products appear in a single broad band with a maximum intensity in spectral regions compatible with the formation of the reductive alkylation products of certain polynuclear aromatic hydrocarbons or the base-catalysed alkylation of certain benzylic carbon atoms. The resonances of the N -alkylation products appear in two distinct bands. These resonances are tentatively assigned to amines produced as a result of reductive alkylation of heterocyclic compounds. The resonances of the 0-alkylation products appear in three distinct bands which can be assigned to alkyl aryl ethers, alkyl aryl ethers with substituents at the adjacent positions, and to alkyl carboxylates. The ratio of ethers to carboxylates in the soluble alkylation products was determined to be 7.8 for butylation and 8.0 for methylation. The Chromatographic fractions contain different amounts of C-, N-, and 0-alkylation products. This finding suggests that the coal structure is not highly uniform.     

单溴四苯基卟啉吸附在AgCl溶胶表面性质研究

合成了单溴四苯基卟啉—— 5 - (邻溴苯基 ) - 1 0 ,1 5 ,2 0 -三苯基卟啉 (H2 L) ,用元素分析 ,红外光谱、电子吸收光谱和氢核磁共振谱确定了其组成和结构。研究了 H2 L在醋酸中电子吸收光谱和在 Ag Cl溶胶上的表面化学反应。结果表明 ,单邻溴四苯基卟啉在冰醋酸中以二酸形式 H4 L2 + 和游离碱 H2 L形式存在 ,二者之间存在着电离平衡 :H4 L2 + =H2 L+2 H+ ;当 p H=7.0～ 1 1 .0时 ,H2 L在Ag Cl溶胶表面发生配位反应生成 Ag( ) L,并且溶液的 p H增大 ,配位反应的速率增大。     

4种喹诺酮类药物分子荧光光谱的量子化学研究

喹诺酮类药物是目前广泛用于治疗各种感染性疾病的化学合成药物。文章采用量子化学B3LYP方法,在6-31g基组水平下对4种喹诺酮类药物进行几何构型优化,经振动分析,均未出现虚频率。在此基础上用CIS方法计算了4种化合物的荧光光谱,所得计算值与实验值基本相符。     

Incoherent scatter spectra due to HF heating in the low ionosphere region

The electron velocity distribution function and the incoherent scatter spectra during ionospheric heating in low ionosphere region are presented with consideration of the elastic collision between electrons and neural particles and the excitation of rotation energy level. The effects of pump frequency and electric fields on the spectra are discussed. With the increase of electric field, the non-Maxwellian feature is enhanced, and with the increase of heating frequency, the non-Maxwellian feature is weakened. The non-Maxwellian factor will bring a large error in ionosphere parameters, which must be considered in the inversion. Supported by the National Natural Science Foundation of China (Grant No. 40310223), the National Key Laboratory of Electromagnetic Environment (LEME), and National Key Technologies R&D Program of China (Grant No. 2006BAB18B06)