Sorption kinetics and microbial biodegradation activity of hydrophobic chemicals in sewage sludge: model and measurements based on free concentrations

In the current study, a new method is introduced with which the rate-limiting factor of biodegradation processes of hydrophobic chemicals in organic and aqueous systems can be determined. The novelty of this approach lies in the combination of a free concentration-based kinetic model with measurements of both free and total concentrations in time. This model includes microbial biodegradation activity of the chemical in the aqueous phase and chemical sorption kinetics with respect to organic carbon and aqueous phases. The time dependency of free and total concentrations of 7-acetyl-1,1,3,4,4,6-hexamethyltetrahydronaphthalene and 7-acetyl-1,1,3,4,4,6-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta(g)-2-benzopyrane in activated sludge was experimentally determined in vitro. Evaporation losses from the test system were also determined. Least-squares regression to optimize the model parameters resulted in a model that is in accordance with the experimental data. Additionally, the model shows that a comparison between the decrease of free and total chemical concentrations in time, in combination with an independent measurement of the organic carbon/water partition coefficient provides information aboutthe rate-limiting step of the degradation process. This information can be used by sewage treatment plant managers to decide whether the microbial biodegradation activity itself or the desorption from organic carbon to the aqueous phase should be improved.     

高速管式离心机转子动力学稳定性的研究

离心机在工业领域、特别是生物、化工、能源等方面具有广泛的应用,研究高速离心机转子系统的稳定性对离心机的设计和性能预测具有重要意义。文章通过建立高速离心机转子系统中旋转流体和转子系统模型,确定主要影响因素和判别方法,最后给出提高高速离心机转子系统稳定性的主要途径:低阻尼,适当高刚度的支撑。     

Using Both Chemical and Biological Fingerprints for the Quality Study of Estrogenic Licorice (Glycyrrhiza uralensis)

ABSTRACT: The quality of phytoestrogenic licorice was studied by using both chemical and biological fingerprints. A recombinant yeast strain that consists of an estrogen responsive element linked with a reporter gene ( ADE2 ) and a transformed human estrogen receptor–containing plasmid was used for screening and evaluation of estrogenic activity in licorice. Several estrogen-like components in licorice were screened, and licoisoflavone B and formononetin were identified. Licorice extracted with 70% ethanol showed 5 different patterns of chemical fingerprints (LR-A, LR-E, LR-F, LR-H, LR-K), as identified by chromatographic analysis. Among these, LR-E exhibited the strongest estrogenic activity, whereas LR-A, LR-F, and LR-H were in the middle, and LR-K had the weakest activity.     

Migration from can coatings: Part 3. Synthesis, identification and quantification of migrating epoxy-based substances below 1000 Da

Bisphenol A-derived glycidyl ethers as well as its reaction products with other lacquer components can migrate into the packed food from epoxy-based can coatings. A sensitive and selective method is presented using high-performance liquid chromatography coupled with ultraviolet light, fluorescence and electrospray ionization-mass selective detection for the identification and quantification of all migrants with a bisphenol A backbone and a molecular weight below 1000 Da, an estimated boundary for the absorption in the gastrointestinal tract. The identification of migrants was confirmed by microreactions of technical bisphenol A diglycidyl ether with solvents and phenols, which provided the fragmentation pattern of the mass selective detection and relative retentions of 42 different bisphenol A-related substances. It was shown by calibration of different isolated and synthesized bisphenol A derivatives that the fluorescence response relies on the amount of bisphenol A moiety in the respective molecule. Therefore, all migrating bisphenol A-related substances below 1000 Da were determined as bisphenol A diglycidyl ether equivalents using a calibration (fluorescence detection) of the commercially available bisphenol A diglycidyl ether monomer. The limit of quantification was set at 5 μg bisphenol A diglycidyl ether equivalents kg^-1 (or 0.8 μg dm^-2). This method was validated for epoxy coatings (0.1 μg dm^-2 limit of detection and 24 μg bisphenol A-related substances below 1000 Da dm^-2 standard deviation, corresponding to 4.4% relative standard deviation). The quantification could be extended by combining the fluorescence response and structural information gained from the mass spectra, which provides more accurate results for each migrant. The calculation is based on the calibration of the bisphenol A chromophore content of the molecule. According to this method, the amount of migrating bisphenol A-related substances below 1000 Da in the acetonitrile extract (assuming a worst case) varied from about 0.4 to 0.7 mg dm^-2 in the examined coatings. The determined amounts comply with about 50% of the total migrate below 1000 Da.     

环丙沙星人工抗原的合成及鉴定

通过化学方法制备了环丙沙星的免疫抗原和包被抗原;分别采用碳二亚胺(EDC)法和氯甲酸乙丁酯法把环丙沙星与BSA进行了偶联制备了人工免疫抗原CIP-BSA,EDC法制备了包被抗原CIP-OVA,经PAGE、紫外分光光度法测定了人工合成抗原的偶联比,EDC法和氟甲酸乙丁酯法制得的CIP-BSA两分子结合比率分别为4:1和11:1,CIP-OVA中两分子结合比率为12:1.这为环丙沙星单克隆抗体的制备奠定了基础.     

京郊鲜食杏白利糖度的便携式光谱快速无损检测方法研究

目的建立京郊鲜食杏白利糖度的定量分析预测模型,实现对京郊鲜食杏品质的快速无损检测。方法使用便携式近红外光谱仪采集900～1700 nm下鲜食杏的漫反射光谱信息,使用多元散射校正(multiplicative scatter correction,MSC)、标准正态变量变换(standard normal variable transformation,SNV)和Savitzky-Golay卷积平滑(Savitzky-Golay smooth,S-G)对原始光谱数据进行预处理,使用Kennard-Stone (K-S)算法以3:1比例将样本集划分成校正集和预测集,利用竞争自适应重加权采样(competitive adaptive reweighted sampling,CARS)算法和连续投影算法(successive projections algorithm,SPA)对光谱进行特征波长筛选,使用偏最小二乘回归(partial least squares regression,PLSR)算法建立京郊鲜食杏白利糖度的预测模型。结果以MSC+S-G+CARS+PLSR算法建立的北京鲜食杏的...     

转谷氨酰胺酶活性基团研究

采用PMSF、NBS、IAc、BrAc、SUAN、NEM、DTT、Na2SO3、EDC、WRK 10种化学修饰剂在一定的条件下选择性修饰转谷氨酰胺酶,研究转谷氨酰胺酶分子中氨基酸侧链基团与酶活性中心的关系。结果表明:PMSF、NBS、IAc、BrAc、SUAN、NEM等化学修饰剂能显著抑制酶活力,而DTT、Na2SO3、EDC、WRK对酶活影响不大,说明丝氨酸残基、色氨酸残基、组氨酸残基、赖氨酸残基、半胱氨酸残基对酶活力影响很大,位于酶的活性中心,二硫键、谷氨酸(天冬氨酸)残基对酶活几乎没有影响,不位于酶的活性中心。     

近红外光谱在小尾寒羊羊肉水分预测中的应用

以南疆小尾寒羊鲜羊肉的含水量为研究对象,首先采集鲜羊肉的光谱数据和水分含量信息;然后分别采用小波变换、多元散射校正以及二者结合的方法预处理数据;最后使用偏最小二乘法对3种方法预处理过的光谱数据建立羊肉水分含量的预测模型,共制备134个样本,根据留一法选择110个样本作为训练集,剩余的24个样本作为预测集.结果表明,采用...     

Improvement of the gelling ability in restructured fish products: effect of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide level and pH

The production of heat-induced gels from raw materials with poor gelling ability remains a technical challenge, for which new solutions have been proposed. The addition to the gel batters of a cross-linking chemical agent, such as 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), may present a valuable tool for the improvement of gelling. Accordingly, a response surface methodology was used to optimize the conditions of EDC application, the EDC concentration (0.0–0.5?%, w/w) and the batters’ pH (4.5–7.5). Results showed that textural, colour, and water-binding properties of heat-induced hake gels were extremely sensitive to EDC content and pH. It was possible to find an optimal EDC level-pH binary common to the various studied parameters, a pH between 4.0 and 5.0 and an EDC concentration of 0.5?%, w/w. Moreover, this experimental work proved to be feasible the achievement of gel products of acceptable textural quality from frozen hake through EDC incorporation in optimal conditions.     

Removal of phenolic endocrine disruptors by Portulaca oleracea

Portulaca oleracea, a garden plant prevalent from spring to autumn in Japan, showed the ability to efficiently remove from water bisphenol A (BPA), which is well known as an endocrine disrupting compound (EDC) having estrogenic properties. In water culture, 50 muM BPA was almost completely removed within 24 h when the ratio of whole plant weight to the water volume was set up at 1 g to 25 ml. The estrogenic activity of the water decreased in parallel with the elimination of BPA. This plant also rapidly removed other EDCs having a phenol group including octylphenol (OP), nonylphenol (NP), 2,4-dichlorophenol (2,4-DCP) and 17beta-estradiol and, thereby, removed the endocrine disrupting activities. In addition, the ability of P. oleracea to remove BPA was not affected by BPA concentration (up to 250 microM), by cultivation in the dark, by temperatures ranging from 15 degrees C to 30 degrees C, or by pH ranging from 4 to 7. Moreover, the ability of P. oleracea to individually remove BPA, NP, and OP was the same as when they were all present. These results suggest that P. oleracea is a promising material for practical phytoremediation of landfill leachates and industrial wastewater contaminated with the tested EDCs.     

化学品生物降解的评价方法

本文介绍了化学品生物降解的定义、化学品在微生物中的曝露实验的方法,总结了有机物好氧生物降解和厌氧生物降解的评价方法。最后介绍了难于生物降解的“三致”型(致癌、致畸、致突变)有机污染物的降解方法,为污染物的降解提供了参考。     

Oxidative degradation of alkylphenols by horseradish peroxidase

Alkylphenols such as bisphenol A (2,2-bis(4-hydroxyphenyl)propane; BPA), p-nonylphenol (p-NP), and p-octylphenol (p-OP) that are known as endocrine disrupters were oxidized by horseradish (Armoracia rusticana) peroxidase (HRP) with H2O2. The optimal pHs for BPA, p-NP, and p-OP were 8.0, 7.0, and 5.0, respectively. The optimal temperature for BPA was 20 degrees C. Although BPA was rapidly degraded by HRP, its degradation depended on the concentration of HRP. Most of the oxidation products of BPA were polymers, although some 4-isopropenylphenol was produced. When male Japanese medaka (Oryzias latipes) were exposed to BPA, vitellogenin in the blood increased. However, no increased vitellogenin was observed in medaka exposed to HRP-oxidized BPA. The enzymatic oxidation of BPA using HRP was able to eliminate its estrogen-like activity.     

Second-order modeling of variability and uncertainty in microbial hazard characterization

This study describes an analytical framework that permits quantitative consideration of variability and uncertainty in microbial hazard characterization. Second-order modeling that used two-dimensional Monte Carlo simulation and stratification into homogeneous population subgroups was applied to integrate uncertainty and variability. Specifically, the bootstrap method was used to simulate sampling error due to the limited sample size in microbial dose-response modeling. A data set from human feeding trials with Campylobacter jejuni was fitted to the log-logistic dose-response model, and results from the analysis of FoodNet surveillance data provided further information on variability and uncertainty in Campylobacter susceptibility due to the effect of age. Results of our analyses indicate that uncertainty associated with dose-response modeling has a dominating influence on the analytical outcome. In contrast, inclusion of the age factor has a limited impact. While the advocacy of more closely modeling variability in hazard characterization is warranted, the characterization of key sources of uncertainties and their consistent propagation throughout a microbial risk assessment actually appear of greater importance.     

最小偏二乘方法和近红外技术快速测定莲子多糖及抗氧化活性

目的对5个主要产区的莲子多糖含量和抗氧化活性进行测定,分析比较各省份莲子质量差异,并进一步采用近红外分析技术构建莲子多糖的快速预测模型。方法采用苯酚-硫酸法测定莲子多糖的含量;利用对1,1-二苯基-2-苦肼基自由基(1,1-diphenyl-2-picozide radical,DPPH)清除率测定莲子的抗氧化活性;并利用偏最小二乘方法构建莲子多糖的快速预测模型。结果实现了5个产地的莲子多糖含量及其抗氧化活性的精确测定;构建的快速预测模型对多糖含量及抗氧化活性预测准确率较好,模型的训练集均方根差(root-mean-square error,RMSEC)为0.0185,测试集均方根差(root-mean-square error of prediction,RMSECP)为0.0236;训练集和测试集相关系数的平方分别达到了0.9592和0.8516。结论本文所构建的快速预测模型能够对不同产地的莲子的多糖含量和抗氧化活性进行快速预测,为评价莲子多糖含量和抗氧化活性提供了科学参考。     

近红外光谱技术在棉＼氨纶面料分析中的应用

利用近红外漫反射光谱技术对棉／氨纶混纺面料进行含量分析。对不同成分含量的样本用高分辨率的光谱扫描,得到信息量丰富的原始光谱;采用一阶导数方法对光谱进行预处理;利用偏最小二乘法建立模型。使用预测数据,对所建立模型进行预测效果分析。结果表明近红外检测可以用于纺织面料含量较低组分的定量分析。     

Estrogenic activity of impurities in industrial grade bisphenol A

The estrogenicities of 10 compounds found as impurities in industrial grade bisphenol A (BPA) were measured by yeasttwo-hybrid assays incorporating the human estrogen receptor alpha(hERalpha) orthe medaka fish (Oryziaslatipes) estrogen receptor alpha (medERalpha). Five impurities showed greater activity than BPA itself in an agonist assay for hERalpha. p-Cumylphenol, the most active of the impurities in the hERalpha assay, was 12 times as active as BPA. The REC10 (10% relative effective concentration: 10% of the activity of 10(-8)M 17,B-estradiol) was 710 nM. Five impurities showed greater activity than BPA in an agonist assay for medERa: 4,4'-(1,3-dimethylbutylidene) bisphenol and 2-(4'-hydroxy-phenyl)-2,4,4-trimethylchroman were nearly equipotent and 9 times as active as BPA, and the REC10 values of these compounds in the medERalpha assay were 280 and 320 nM, respectively. Comparison of the experimentally determined estrogenicities of mixtures of BPA and 4,4'-(1,3-dimeth-ylbutylidene) bisphenol and those calculated by the concentrations addition (CA) method confirmed the suitability of the method for the prediction of the estrogenicities of the mixtures of BPA and its phenolic analogues. The measured estrogenicities of four samples of industrial grade BPA and laboratory grade (pure) BPA were not significantly different in either the hERalpha assay or the medERalpha assay (p > 0.05 in each case). We conclude that the impurities in industrial grade BPA, although some are of much higher estrogenic activity than BPA itself, do not significantly increase the estrogenicity of the industrial compound and therefore do not increase possible adverse health effects from such activity.     

基于化学计量学方法的黄水还原糖预测模型研究

目的 利用预处理对近红外光谱原始数据集进行降噪及非相关信息剔除后, 采用间隔偏最小二乘法(interval partial least squares, iPLS)与连续投影算法(successive projections algorithm, SPA)联用的特征波段筛选算法降低模型复杂度, 建立高精度低冗余度的黄水还原糖预测模型。方法 在最佳的3种预处理方法的基础上, 利用竞争性自适应重加权算法、间隔偏最小二乘回归法、连续投影算法对250个样品的光谱数据进行特征波段筛选, 采用光谱-理化值共生距离算法进行样品集的划分, 划分比例为3:1。结果 黄水还原糖预测模型经iPLS-SPA算法处理后, 得到了更高的精度与稳定性, 且预测可决系数较原始数据集提升7.28%, 为0.962; 预测均方根误差下降85.40%, 为0.220; 光谱变量数下降95.46%, 为100。结论 在预处理后加入iPLS-SPA特征波段筛选算法, 能够提升黄水还原糖预测模型精度, 极大减低冗余度。     

基于高维多元数据的酒体感官评价可视分析

酒体质量评价以感官鉴定为主,但感官评价易受人的身体条件和经验等因素的影响。为提高评价的稳定性和有效性,建立以理化指标数据为依据的评价方法。本文提出了一种基于大数据可视分析的研究方法,挖掘高维多元指标数据对酒体感官特性的影响。首先,对高维多元指标数据的相关性,以及与感官评价的相关性进行分析,通过图模型阐释关系特性,初步建立面向领域的可视分析方法。然后,采用基于机器学习的数据分析技术,结合感官评价构建酒体质量评价模型。最后,结合评价模型对酒体指标参数的重要性进行分析。在此基础上,对模型的评价效果进行了验证,分别选取两类样本进行对比,一类样本包含重要性得分较高的6 项理化指标,包括酒体密度、残糖、挥发性酸、酒精度、硫酸酯和非挥发性酸,另一类样本包含全部11 项理化指标,验证结果显示两类样本的预测结果相近,分类预测误差仅相差0.4%,表明以上6项理化指标是影响感官评价的主要成分。该可视分析方法可降低理化指标的维数,并保留酒体质量的特征信息,用于酒体质量的评价,对酒体质量科学化评价起到重要作用。