山东沿海6市市售水产品中多氯联苯污染特征及健康风险评估

应用气相色谱-三重四极杆质谱法测定水产品中的多氯联苯(Polychlorinated Biphenyls,PCBs),以评价山东沿海6市市售鱼类和双壳贝类样品中PCBs的污染状况及健康风险。结果显示,PCBs在山东沿海市售水产品中的含量为0.046~5.548 ng·g^(-1),平均值为0.627 ng·g^(-1),远低于国家标准限值。污染程度处于较低水平,通过食用水产品摄入的PCBs可能引起的接触风险和致癌风险较低。水产样品中7种指示性PCBs均有检出,组成以中氯代PCBs为主。鱼类中PCBs残留量比贝类略高,贝类中三氯联苯的占比更高。不同城市水产品的污染水平无统计学差异(P>0.05)。

高压大功率IGBT用液晶环氧性能研究(一):热导率与耐热特性

随着绝缘栅双极型晶体管(IGBT)在工业应用上向高电压、大功率方向发展,对其散热、耐热、绝缘等性能提出了更高的要求,亟须研制高性能的绝缘灌封材料。该文提出利用联苯型环氧单体与联苯胺固化剂双液晶分子构筑液晶畴,着重调控材料热学及电气性能。系列论文(一)研究了其相关热性能,研究表明通过利用液晶联苯胺固化剂与联苯液晶环氧构建具有π-π堆砌液晶畴及高交联密度网络结构的固化物,其玻璃化转变温度Tg可达247℃,与传统双酚A型环氧的Tg相比提高了76.4%;热导率提升至0.351 W/(m·K),相对于双酚A型环氧提高了64.0%。此外,通过分子动力学模拟对交联聚合物的自由体积、Tg、热导率等微观参数及宏观性能进行了机理分析。

高压大功率IGBT用液晶环氧性能研究(二):电气绝缘特性

高压大功率IGBT用灌封材料绝缘失效是制约其快速发展的关键因素之一。由两篇论文组成的系列论文旨在通过构建液晶畴的研究思路协同提升环氧绝缘灌封材料的导热、耐热和电气绝缘性能。该文是系列论文(二),对液晶环氧树脂的击穿特性、局部放电、陷阱能级和介电特性等进行了研究,研究结果表明,通过π-π自组装构筑的液晶畴可有效地降低环氧固化后的自由体积,进而抑制载流子迁移,与双酚A型环氧相比,展现出更高的击穿场强(126.72 kV/mm)和更低的局部放电量(1.37 pC)。热刺激去极化电流研究表明,该联苯环氧-联苯固化剂双液晶交联材料具备较高的陷阱能级,捕捉电子能力增强。此外,利用分子动力学模拟软件仿真计算了交联体系的自由体积、电场下均方位移、击穿场强等参数,并对材料的电气性能机理进行了分析。研究结果可为新型环氧树脂在高压大功率IGBT灌封绝缘材料领域的工程应用提供一定的参考。

环境污染物的跨胎盘转移效率研究进展

随着工业化发展,环境污染物的种类和数量不断增加。环境污染物广泛存在于空气、食品和生活用品等传播介质中,妊娠期接触环境污染物不仅影响孕妇健康,还可能对分娩结果及胎儿的发育产生不利影响。胎盘作为母体和胎儿之间的屏障,对部分环境污染物具有选择性阻隔作用,即一些污染物被阻留于母体血液,而另一些环境污染物通过被动扩散、胎盘转运蛋白或内吞作用穿过胎盘屏障,进入胎儿脐带血中。跨胎盘转移效率(transplacental transfer efficiency,TTE)即污染物在脐带血中与在母体血液中水平的比值,常用于评估环境污染物跨越胎盘屏障的能力。TTE与污染物的相对分子质量、脂溶性、极性和结构特征等理化性质有关;母体和胎儿的健康状况、胎盘血流量、胎盘成熟度、胎盘转运蛋白和代谢酶的功能也会显著影响污染物的转移过程。本文总结了TTE的研究方法以及近年来有关环境污染物(全氟和多氟烷基物质(PFASs)、多溴二苯醚(PBDEs)、多氯联苯(PCBs)和有机氯农药(OCPs)等)的TTE研究进展,并讨论了影响TTE的主要因素。本文对环境污染物的跨胎盘转移机制研究具有指导意义,并有助于评估环境污染物对孕妇和胎儿健康风险的影响。

Polychlorinated biphenyls in the atmosphere of Taizhou,a major e-waste dismantling area in China

PM2.5, total suspended particles （TSP） and gas phase samples were collected at two sites of Talzhou, a major e-waste dismantling area in China. Concentrations, seasonal variations, congener profiles, gas-particle partitioning and size distribution of the atmospheric polychlorinated biphenyls （PCBs） were studied to assess the current state of atmospheric PCBs after the phase out of massive historical dismantling of PCBs containing e-wastes. The average ∑38PCBs concentration in the ambient air （TSP plus gas phase） near the e-waste dismantling area was （12,407 ± 9592） pg/m^3 in winter, which was substantially lower than that found one decade ago. However, the atmospheric PCBs level near the e-waste dismantling area was 54 times of the reference urban site, indicating that the impact of the historical dismantling of PCBs containing e-wastes was still significant. Tri-Penta-CBs were dominant homologues, consisting with their dominant global production. Size distribution of particle-bound PCBs showed that higher chlorinated CBs tended to partition more to the fine particles, facilitating its long range air transportation.

Occurrence and congeners specific of poiychlorinated biphenyls in agricultural soils from Southern Jiangsu, China

A total of 198 agricultural soil samples were collected from Zhangjiagang and Changshu in Southern Jiangsu for analysis of 13 polychlorinated biphenyls （PCBs） in order to assess the levels of pollution, sources, area distribution, and potential risk for the environment. All methods were rigorously tested and an adequate quality control was ensured. Only one site had no PCBs residues, and the highest total PCBs concentration in the surface soils was 32.83 ng/g. The average concentration in all the soil samples was 4.13 ng/g, signaling low-level pollution. Tetra-, penta-, and hexa-chlorinated biphenyls were dominant species in soil samples, accounting for more than 75% of ∑PCBs in the soil samples. PCB118 was the most abundant congener in all the samples. The PCB118 was about 20% of ∑PCBs. The soil organic matter content showed only a weak correlation with the levels of all PCB congeners, in which a better correlation was noted for the more volatile lighter PCB congeners than for the heavier homologues. To a certain extent, the sources and land use seemed to influence the levels of PCBs.

Levels and distributions of polychlorinated biphenyls in sewage sludge of urban wastewater treatment plants

Concentrations of polychlorinated biphenyls （PCBs） have been measured in sewage sludge samples from 8 urban wastewater treatment plants in Beijing, China. The PCB congeners were analyzed by isotope dilution high resolution gas chromatography/high resolution mass spectrometry method. The concentration of PCBs ranged from 65.6 to 157 ng/g dry weight （dw）, with a mean value of 101 ng/g dw. The dioxin-like PCB WHO-TEQs （World Health Organization-Toxic Equivalents） of the sludge were lower than 1 pg /g dw. Consequently, all the concentrations of PCBs in sludge samples were below the upper limit for land application according to the Chinese legislation law for agriculture use. The PCB homologue profiles in sludge samples were dominated by tri-CBs and tetra- CBs. Similar distributions have been found in one of the Chinese PCB commercial products. The patterns of dioxin-like and indicator congeners observed in this study were quite similar in all samples. The predominant congener for dioxin-like and indicator PCBs were PCB-118 and PCB-28, respectively, while PCB-126 had the highest TEQ value.

Biphenyl Ferulate from Glehnia littoralis

From the underground parts of Glehnia littoralis Fr. Schmidt ex Miquel (Umbelliferae), a new compound named glehnilate was obtained. Its structure was determined by analysis of its spectral data.

Impact of poly chlorinated biphenyl (Aroclor 1254) and vitamin C on antioxidant system of rat ventral prostate

Aim: To evaluate the effect of polychlorinated biphenyls (PCB) and vitamin C on ventral prostatic antioxidant system in adult male rats. Methods: A group of 20 adult male rats were administered ip Aroclor 1254 in corn oil at a dose of 2 mg·kg-1·day-1 for 30 days. Ten control rats were administered only the vehicle. After 30 days the treated rats were divided at random into 2 sub-groups of 10 animals each. One sub-group received vitamin C at a dose of 500 mg·kg-1·day-1 for 10 days. The other group was maintained as Aroclor 1254 control. Twenty-four hours after the last treatment the rats were killed by decapitation. Ventral prostatic homogenate was prepared and used for the estimation of enzymatic antioxidants, including superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) and hydrogen peroxide (H2O2), lipid peroxidation (LPO) and prostatic acid phosphatase. The serum levels of total T3, total T4, TSH, testosterone and estradiol were also assayed. Results: The body weight and ventral prostatic weight were reduced in PCB treated rats. The activities of SOD, CAT, GST and acid phosphatase were decreased while the levels of H2O2 and lipid peroxidation were increased in the ventral prostate of PCB treated rats. Administration of vitamin C restored these parameters. Serum levels of thyroid hormones, estradiol and testosterone were decreased in PCB treated animals. Administration of vitamin C restored the thyroid hormone levels. Conclusion: PCB induces oxidative stress and decreases the antioxidant enzymes in the ventral prostate of adult male rats; the effects could be reversed by the administration of vitamin C.

Synthesis and biological evaluation of nitric oxide-releasing sixalkoxyl biphenyl derivatives as anticancer agents

A series of novel nitric oxide-donating sixalkoxyl biphenyl derivatives （14a-1） were synthesized by coupling furoxan with alkoxyl biphenyl skeleton using amino acids as the spacers, and their cytotoxicity against HepG2 cells in vitro were evaluated by MTT method. It was found that 14c, 14d, 14f, 14i, 14j and 14k showed more potent cytotoxic activities than control 5-fluorouracil. NO release assay of target compounds indicated that the maximum amount of NO released by most active compounds 14c and 14j was about 6 × 10^-2 μmol/L, whereas 14a and 14h with very weak activity only released NO of 1 × 10^-2 μmol/L.

Synthesis,Characterization and Fluorescence Properties of Europium,Terbium Complexes with Biphenyl-4-Carboxylic Acid and o-Phenanthroline

Two series of solid complexes of europium and terbium with biphenyl 4-carboxylic acid and phen were synthesized and characterized in this report. Their elemental analysis, molar conductivities and TG-DTA studies indicate that the complexes have the composition of Eu(phen)L3·1/2H2O, Eu0.5RE0.5(phen) L3·1/2H2O; Tb (phen) L3·H2O and Tb0.5 RE0.5(Phen)L3·1/2H2O. (RE = Y3+, La3+ and Gd3+; L = biphenyl 4-carboxylic acid; phen = o-Phenanthroline). The studies of their IR, UV 1H NMR and molar conductivities demonstrate that biphenyl 4-carboylic acid is bounded with RE (III ) ion. Rare earth ions coordinate with two nitrogen atoms of phen molecules directly in these rare earth complexes. The fluorescence spectra and fluorescence lifetimes of the rare earth complexes show that the fluorescent intensity and lifetime of a series of europium complexes are longer than those of the series of terbium complexes as having the some ligands. There are better fluorescent intensity and lifetime of hetero-nuclear rare earth complexes than homo-nuclear rare earth complexes for europium complexes. The fluorescence emission intensity of Eu3 + is raised by inert fluorescent rare earth ions (Y3+ , Gd3+ and La3+ ), but in Tb3+ hetero-nuclear rare earth complexes the intensity of Tb3+ ions are quenched by the inert fluorescent rare earth ions.

A QSRR Study on the Chromatographic Retention Indices of Hydroxylated Polychlorinated Biphenyls

Hydroxylated Polychlorinated Biphenyls （HO-PCBs） are the metabolite of polychlorinated biphenyls and have drawn much attention because they have hazard on human health and ecosystems. Molecular connectivity index calculation has been performed for 19 HO-PCB compounds. A number of statistically based parameters have been extracted. Linear relationship between chromatographic retention index （RI） and the molecular connectivity index of 15 compounds in the training set has been established by multiple linear regression method. The other 4 HO-PCBs are used as the external test set. The result shows that the parameters can be well used to express the quantitative structure-retention relationship （QSRR） of HO-PCBs. Good stability and predictive ability have been demonstrated by leave-one-out cross-validation and the external test set.

Photolysis of mono- through deca-chlorinated biphenyls by ultraviolet irradiation in n-hexane and quantitative structure-property relationship analysis

The photolysis of 16 polychlorinated biphenyls （PCBs） （including mono- through deca-chlorinated） in n-hexane was investigated under ultraviolet irradiation using a 500-W high-pressure mercury lamp. Photolysis of PCBs follows pseudo-first-order reaction kinetics, with photolysis rate constants ranging between 0.0011 s^-1 for PCB-52 and 0.0574 s^-1 for PCB-118. The degradation rates of PCBs by high-pressure mercury lamp irradiation were remarkably independent with respect to the degree of chlorination. Furthermore, partial least squares （PLS） models were developed to provide insight into which aspect of the molecular structure influenced PCB photolysis rate constants. It was found that the photolysis rates of PCBs increased with an increase in the net charge on the carbon atom （qc）, （ELUMO-EHOMO）^2, and the Y-axis dipole moment （μy） values, or the decrease in the energy of the second highest occupied molecular orbital （EHOMO-1）, energy of the lowest unoccupied molecular orbital （ELUMO）, ELUMO ＋ EHOMO, ELUMO - EHOMO, most positive atomic charge （q^＋）, and the twist angle of the chlorine atom （TA） values.

Synthesis and characterization of novel poly(aryl ether sulfone ketone)s containing phthalazinone and biphenyl moieties

A novel series of poly（aryl ether sulfone ketone）s （PPESKs） containing phthalazinone and biphenyl moieties were prepared by two-step nucleophilic polycondensation reaction. The ^-Mw values of these copolymers were between 38,330 and 67,900. The glass transition temperatures （Tg） and 5% decomposition temperatures were ranged in 253-269 ℃ and 488-500 ℃, respectively, The structures of these copolymers were confirmed by FT-IR and ^1H NMR. Moreover, all the resultant copolymers were amorphous determined by wide angle X-ray diffraction （WAXD）.

Isolation and characteristics of a novel biphenyl-degrading bacterial strain,Dyella ginsengisoli LA-4

A novel biphenyl-degrading bacterial strain LA-4 was isolated from activated sludge. It was identified as Dyella ginsengisoli according to phylogenetic similarity of 16S rRNA gene sequence. This isolate could utilize biphenyl as sole source of carbon and energy, which degraded over 95 mg/L biphenyl within 36 h. The major metabolites formed from biphenyl, such as 2-hydroxy-6-oxo-6- phenylhexa-2,4-dienoic acid （HOPDA） and benzoic acid, were identified by LC-MS. The crude cell extract of strain LA-4 exhibited the activity of 2,3-dihydroxybiphenyl 1,2-dioxygenase （2,3-DHBD） and the kinetic parameters Km was 26.48 μmol/L and Vmax was 8.12 U/mg protein. A conserved region of the biphenyl dioxygenase gene bphA1 of strain LA-4 was amplified by PCR and confirmed by DNA sequencing.

Degradation and mineralization of 2-chloro-, 3-chloro- and 4-chlorobiphenyl by a newly characterized natural bacterial strain isolated from an electrical transformer fluid-contaminated soil

A bacterium classified as Achromobacter xylosoxidans strain IR08 by phenotypic typing coupled with 16S rRNA gene analysis was isolated from a soil contaminated with electrical transformer ?uid for over sixty years using Aroclor 1221 as an enrichment substrate. The substrate utilization profiles revealed that IR08 could grow on all three monochlorobiphenyls (CBs), 2,4’- and 4,4’-dichlorobiphenyl as well as 2-chlorobenzoate (2-CBA), 3-CBA, 4-CBA, and 2,3-dichlorobenzoate. Unusually, growth was poorly sustaine...

Development and characterization of new polyclonal antibodies specific for three polychlorinated biphenyls

Three polychlorinated biphenyls （PCBs） congeners and their corresponding haptens bearing four carbon length carboxylic groups that can be linked to a protein for raising antibodies were synthesized. The three resultant immunogens were fabricated and used to stimulate immune responses in rabbits to survey the characteristics of the haptens. Three of the resultant polyclonal antibodies （Pabs） were obtained. The antiserum exhibited relatively high antibody titres （1：32-64） in double agar diffusion.

Levels of polychlorinated biphenyls in 1,4-dichlorobenzene mothballs

Although polychlorinated biphenyls(PCBs) are globally recognized pollutant, an understanding of their resources as by products in chemical industry is poorly investigated. This paper presents data from a study that was conducted in order to determine the extent of PCBs in 1,4 dichlorobenzene( p DCB) mothballs. Total PCBs and dioxin like PCBs were detected in five mothball samples. Total PCB concentrations ranged from 328 ng/g to 1798 ng/g, while the levels of WHO TEQ were between 0 16 pg/g and 13 pg/g. Mean concentrations of total PCBs and WHO TEQ in the samples were 724 ng/g and 3.2 pg/g, respectively. The highest level of PCB congeners was that of trichlorinated biphenyls(537 ng/g), which maybe due to the relatively low chlorination in the process of p DCB production. A mechanism of the formation of PCBs from polychlorinated benzene in the presence of chlorine is also suggested. The results suggested that re estimation on the risk of p DCB products, especially the products for daily use such as mothballs, is expected.

Estimation of Aqueous Solubility (-lgS_w) of All Polychlorinated Biphenyl (PCB) Congeners by Density Functional Theory and Position of Cl Substitution (NPCS) Method

Optimization calculations of 209 polychlorinated biphenyls （PCBs） were carried out at the B3LYP/6-31G^＊ level. It was found that there is significant correlation between the Cl substitution position and some structural parameters. Consequently, Cl substitution positions were taken as theoretical descriptors to establish a novel QSPR model for predicting –lgSw of all PCB congeners. The model achieved in this work contains four variables, of which r^2 = 0.9527, q^2 = 0.9490 and SD = 0.25 with large t values. In addition, the variation inflation factors （VIFs） of variables in this model are all less than 5.0, suggesting high accuracy of the –lgSw predicting model. And the results of cross-validation test and method validation also show that the model exhibits optimum stability and better predictive capability than that from the AM1 method.

Separation of Biphenyl Nitrile Compounds by Microemulsion Electrokinetic Chromatography with Mixed Surfactants

A mixture of nine biphenyl nitrile compounds with high hydrophobicity and similar structures was successfully separated by microemulsion electrokinetic chromatography (MEEKC) within 30 min. The buffer system contained 100 mmol/L sodium dodecyl sulfate (SDS), 80 mmol/L sodium cholate (SC), 0.81% heptane, 7.5% n-butanol, 10% acetonitrile and 10 mmol/L borate. The addition of SC, organic modifiers, sample preparation and temperature all showed remarkable effect on the separation. Meanwhile, the MEEKC method was briefly compared with micellar electrokinetic chromatography (MEKC) method.