污染场地土壤调查布点及采样方法探讨

随着社会经济的不断发展,逐渐摒弃以往粗放型的经济发展模式,大量工业企业关停并转或搬迁,很多工业用地变为城市建设用地被再次开发利用.然而由于长期粗放型的发展,对生态环境造成严重污染,土壤污染问题成为不可忽视的难题,如何有效调查和控制土壤污染成为环境监测人员面临的一项重要任务.本文针对污染场地土壤调查工作展开研究,从土壤调...     

基于近红外光谱快速定量检测面粉中曲酸的方法建立

利用近红外光谱技术快速定量检测面粉中非法添加的褐变抑制剂曲酸。选取市场上常见3?种基本类型的面粉（高、中、低筋面粉）,分别制备曲酸质量分数为0.0%、0.5%、1.0%、3.0%、5.0%、10.0%的面粉样品,并采集其在1?000～2?400?nm波段下的光谱数据。对比不同预处理下高筋面粉样品数据所建偏最小二乘（partial least squares,PLS）回归模型效果,选取Savitzky-Golay一阶导数为最优预处理方法。采用区间偏最小二乘（interval partial least squares,iPLS）法选取1?088.8～1?153.5?nm为最佳光谱区间。结果表明,基于最佳光谱区间所建PLS回归模型预测效果优于基于全波段光谱数据所建模型。进一步,基于所选最优区间对中、低筋面粉和混合样品集分别建立PLS回归模型。高、中、低筋面粉及混合样品集基于最优区间的PLS模型的决定系数为0.949～0.972,标准误差为0.581%～0.830%,验证集标准偏差与预测标准偏差的比值为4.171～4.830。结果表明,基于最优区间的近红外光谱方法对不同类型面粉中曲酸质量分数为1.0%～10.0%的样品具有较好的预测结果,结合具有低检测限的化学检测方法,在对大批量样品的检测中可提高检测效率。     

黄腐酸对蛋鸡生产性能的影响

将2 000只400日龄健康海塞克斯蛋鸡随机分成2组,对照组饲喂基础日粮.试验组在基础日粮中添加0.5 g/d黄腐酸产品,研究其对蛋鸡生产性能的影响.结果表明:与对照组相比,试验组平均蛋重极显著提高7.40%、平均产蛋率极显著提高5.20%、料蛋比极显著降低15.07%、死亡率降低90%、破蛋率降低42.5%、平均耗料量降低4.04%.     

酱油中总酸和氨基酸态氮成分的快速检测及研究

本文论述了应用ASD-LabSpec近红外光谱仪实现酱油中总酸和氨基酸态氮的测量,根据近红外(NIR)光谱的振动吸收强度与被测物质特征信息之间的关系,对酱油样品采集近红外光谱,透射光谱经过基线校正处理后,采用偏最小二乘(PLS1)以及完全交互验证法,与酱油总酸和氨基酸态氮进行线性回归,建立了预测模型。用该模型对随机抽取未参与建模的8个酱油样品的总酸和氨基酸态氮进行了预测,预测结果的相关系数分别为:R12=0.97;R22=0.98以及标准偏差分别为:STDEV1=0.09;STDEV2=0.07**,该文章应用[模型回归系数图],解析了被检测物质成分与模型之间的关联性。     

Incorporation of Eu(III) into hydrotalcite: a TRLFS and EXAFS study

The behavior of radionuclides in the environment (geo-, hydro-, and biosphere) is determined by interface reactions like adsorption, ion exchange, and incorporation processes. Presently, operational gross parameters for the distribution between solution and minerals are available. For predictive modeling of the radionuclide mobility in such systems, however, individual reactions and processes need to be localized, characterized, and quantified. A prerequisite for localization and clarification of the concerned processes is the use of modern advanced analytical and speciation methods, especially spectroscopy. In this study, Eu(III) was chosen as an analogue for trivalent actinides to identify the different species that occur by the Ln(III)/hydrotalcite interaction. Therefore, Eu(III) doped Mg-Al-Cl-hydrotalcite was synthesized and investigated by TRLFS, EXAFS, and XRD measurements. Two different Eu/hydrotalcite species were obtained. The minor part of the lanthanide is found to be inner-sphere sorbed onto the mineral surface, while the dominating Eu/hydrotalcite species consists of Eu(III) that is incorporated into the hydrotalcite lattice. Both Eu/hydrotalcite species have been characterized by their fluorescence emission spectra and lifetimes. Structural parameters of the incorporated Eu(III) species determined by EXAFS indicate a coordination number of 6.6 +/- 1.3 and distances of 2.41 +/- 0.02 A for the first Eu-OH shell.     

Interaction of Eu(III)/Cm(III) with alumina-bound poly(acrylic acid): sorption, desorption, and spectroscopic studies

This paper contributes to the comprehension of kinetic and equilibrium phenomena governing trace metal ion sorption on organic matter coated mineral particles. Sorption and desorption experiments were carried out with trivalent metal ions M(III) (M = Eu, Cm) and poly(acrylic acid) (PAA)-coated alumina colloids at pH 5 in 0.1 M NaClO4. Under these conditions, M(III) interaction with the solid is governed by sorbed PAA. The results were compared with spectroscopic data obtained by time-resolved laser-induced fluorescence spectroscopy (TRLFS). Within less than 30 s, a state of local equilibrium is reached between M(III) and adsorbed poly(acrylic acid). M(II) bound to the organic-mineral surface and to dissolved PAA keeps five water molecules in its first hydration sphere. Interaction of M(III) with alumina-bound PAA appears to be strongerthan with dissolved PAA. With increasing contact time, a change of the metal ion speciation occurs at the organic-mineral surface. This change is explained quantitatively by kinetically controlled reactions, which succeed a rapid local equilibrium. The experimental findings suggest, in agreement with model calculations, that a part of the initially sorbed M(III) is slowly converted to a kinetically stabilized species, thereby losing water molecules from the first coordination sphere as indicated by TRLFS. This species might be assigned as a ternary Al2O3-M(III)-PAA complex. The second part of the initially bound M(II) appears to experience as well kinetically controlled reactions, however, without showing changes in the first coordination sphere. We assume that the kinetic stabilization is the consequence of rearrangement processes of the PAA at the alumina surface.     

Monitoring of Beer Filtration Using Photon Correlation Spectroscopy (PCS)

In this work, different aspects of particles size distribution in filtered beer were investigated. The utilisation of commercial cellulase or protease formulations influenced significantly the stability of filtered beer. By using Photon Correlation Spectroscopy (PCS) untreated beer samples at 6 and 20°C showed good “chill” stability, while the samples treated with exogenous enzymes showed a significant modification in the particles size distribution and reduced colloidal stability. The particles size distribution in the filtrate appeared to be related to the decrease of the cut‐off size of the membrane and of the flux from the membrane. As reported, the largest particle size diameter flowing through the membrane decreased in each type of sample over the course of the filtration, due to the fouling of the filtering media. The results allowed confirmation that at the beginning of the filtration trials the main fouling cause was the decrease of the pores size within the membrane structure, more than cake formation over the membrane surface, although this second effect prevailed after a certain time.     

Evaluation of Metal Concentrations in Red Tilapia (Oreochromis spp) from Three Sampling Sites in Jelebu, Malaysia Using Principal Component Analysis

Concentration of V, Mn, Fe, Co, Cu, Zn, As, Se, Cd, and Pb in muscle, liver, and gill tissues of red tilapia (Oreochromis spp) sampled from three different aquaculture sites which include earthen pond, ex-tin mining pool, and concrete tank in Jelebu, Negeri Sembilan, were determined using microwave-assisted digestion–inductively coupled plasma-mass spectrometry. Accumulation patterns relating organs and elements, as well as origins and elements, were evaluated using multivariate statistics. With the aid of principal component analysis, it is possible to visualize the distribution pattern of metals in different organs as well as clustering tendencies of tilapia samples according to the production sites. In general, levels of V, Co, Fe, Cu, Zn, Se, and Cd in liver were higher than those in muscles and gills, whereas Mn and Pb were higher in gills while As in muscles. Results from principal component analysis revealed that there are similar pattern of metal distribution among organs regardless of the production sites. It is also suggested that Cu, As, and Pb are the best describers in characterizing the studied organs, where liver tissues are associated with high Cu, gills with high Pb, and muscles with high As. On the other hand, V, Co, and Pb are observed to be key discriminants for sample origins.     

Uptake of Cm(III) and Eu(III) by calcium silicate hydrates: a solution chemistry and time-resolved laser fluorescence spectroscopy study

The interaction of the two chemical homologues [Cm(III) and Eu(III)] with calcium silicate hydrates (CSH phases) at pH 13.3 has been investigated in batch-type sorption studies using Eu(III) and complemented with time-resolved laser fluorescence spectroscopy (TRLFS) using Cm(III). The sorption data for Eu(III) reveal fast sorption kinetics and a strong uptake by CSH phases with distribution ratios of (6 +/- 3) x 10(5) L kg(-1). Three different Cm(III) species have been identified: A nonfluorescing species, which was identified as a curium hydroxide (surface) precipitate, and two fluorescing Cm(III)/CSH-sorbed species. The fluorescing sorbed species have characteristic emission spectra with main peak maxima at 618.9 and 620.9 nm and fluorescence emission lifetimes of 289 +/- 11 and 1482 +/- 200 micros, respectively. From the fluorescence lifetimes, it was calculated that the two fluorescing Cm(III) species have one or two and no water molecules left in their first coordination sphere, suggesting that these species are incorporated into the CSH structure. A structural model for Cm(III) and Eu(III) incorporation into CSH phases is proposed based on the substitution for Ca at two different types of sites in the CSH structure.     

Investigation of the Interaction Between Gallic Acid and α-Amylase by Spectroscopy

Gallic acid is one of the important polyphenols in plants and it inhibits α-amylase. The interaction between gallic acid and α-amylase was investigated by fluorescence quenching spectroscopy, UV-vis spectroscopy, synchronous spectroscopy, and the three-dimensional fluorescence spectroscopy under mimic physiological conditions. The result of the emission quenching at different temperatures revealed that there are static quenching of intrinsic fluorescence of α-amylase induced by gallic acid and a complex of gallic acid-α-amylase was formed. The results obtained from the evaluation of three-dimensional fluorescence spectra, UV-vis spectra, and synchronous spectra suggested that the association between gallic acid and α-amylase did change the molecular conformation of α-amylase. Gallic acid can enter the primary substrate-binding pocket and alter the microenvironment around tryptophan and tyrosine residues.     

傅立叶变换红外光谱检测过一硫酸处理羊毛表面的研究

运用傅立叶红外的衰减全反射技术，对未处理羊毛样品，过一硫酸处理样品和经过一硫酸处理后再用亚硫酸钠处理的样品进行研究，检测羊毛表面胱氨酸的各种氧化产物的特征峰，并计算出峰面积，分析过一硫酸和亚硫酸钠与胱氨酸的作用机理。     

成品白酒中酸酯总量的近红外检测

为了建立成品白酒中酸酯总量的近红外模型,以达到快速检测酸酯总量的目的,本文采用回流及酸碱滴定法测定成品白酒中酸酯总量的化学值,与成品白酒在1 mm及8 mm光程比色池的近红外光谱图相结合,采用内部交叉检验法及外部独立验证建立了成品白酒中酸酯总量的近红外模型.结果表明:成品白酒中的酸类和酯类物质在近红外区有特异性吸收,1...     

分子对接结合荧光光谱法探究单宁酸与血清蛋白结合的pH依赖性

探明单宁酸(TA)与牛血清蛋白(BSA)/人血清蛋白(HSA)之间的相互作用机制,对于开发蛋白基活性成分载体和递送机制研究具有重要意义。血清白蛋白(BSA/HSA)是常用可溶性载体蛋白,含有多个疏水腔作为活性成分结合位点。本文采用荧光发射光谱研究不同pH值(7.4,5.0,4.0)条件下TA对BSA/HSA荧光猝灭作用,并通过数学方程计算猝灭常数和热力学参数,分析荧光猝灭机理,最后通过位点Marker试验和分子对接技术确定结合位点。结果表明:在不同pH值条件下TA对BSA/HSA荧光均产生猝灭作用,当生理pH 7.4时,猝灭率最高。非线性拟合得到TA与血清蛋白的结合常数在105～107L/mol数量级,说明结合能力很强,pH值显著影响结合常数(P0.05),当生理pH 7.4时,结合常数最大。热力学参数与分子对接表明BSA/HSA与TA主要通过氢键和疏水相互作用结合。位点Marker试验和分子对接表明,在pH 7.4时,BSA/HSA与TA结合位点均位于结构域ⅡA和ⅢA之间的疏水腔内,Sudlow's site Ⅰ位点附近。试验证实TA与BSA/HSA的结合存在pH依赖性,对设计开发蛋白-TA载体提供了理论参考,对TA应用有指导意义。     

近红外光谱技术快速无损评价罗非鱼片新鲜度

利用傅里叶变换近红外光谱仪采集绞碎前后罗非鱼片背肉及腹肉的近红外光谱,并将其与总挥发性盐基氮（total volatile basic nitrogen,TVB-N）含量进行拟合,构建定量预测模型。在建模过程中,比较三点平滑、九点平滑（smoothing average 9 points,sa9）、九点卷积平滑（smoothing savitzky-golay 9 points,sg9）、一阶导数（1stderivative,Db1）、趋近归一化、单位长度归一化、标准正态变换、多元散射校正以及它们与Db1结合对光谱进行预处理的模型效果。结果表明,sg9和Db1相比于其他预处理方法可以较好地消除光谱噪音,提高模型预测能力,且各方法在与Db1联合使用后,模型的预测准确性以及建模效率普遍得到了提升。继续对光谱的波数范围进行筛选,剔除无关信息后,模型效果得到进一步提升,绞碎前背肉模型的校正集和验证集决定系数由0.870、0.821上升到了0.973、0.925,校正集和验证集标准偏差由2.152、2.991 mg/100 g减小到了1.032、1.581 mg/100 g。比较各模型效果可知,利用绞碎后的鱼肉光谱进行建模时效果要好于绞碎前的鱼肉。其中,以绞碎后腹肉模型的效果为最优,其验证集决定系数以及标准偏差分别为0.984、0.879 mg/100 g。但在综合考虑实际应用中快速、无损等需求后,绞碎前的鱼肉所建模型仍具有明显优势。最终,本研究选用绞碎前腹肉建立模型,校正集与验证集决定系数分别为0.982、0.976,校正集与验证集标准偏差分别为0.962、1.006 mg/100 g,在预测罗非鱼片TVB-N含量,快速、无损评价其新鲜度方面显示出了巨大潜力。     

Interaction of Phytic Acid with the Metal Ions, Copper (II), Cobalt (II), Iron (III), Magnesium (II), and Manganese (II)

The combination of phytic acid with the metal ions of cobalt (II), magnesium (II), manganese (II), copper (II), and iron (III) has been investigated. With the experimental conditions used, in all cases, the products isolated were amorphous powders with nonstiochiometric atomic ratios.     

Adsorption of Pb(ll) and Eu(III) by oxide minerals in the presence of natural and synthetic hydroxamate siderophores

Trihydroxamate siderophores have been proposed for use as mediators of actinide and heavy metal mobility in contaminated subsurface zones. These microbially produced ligands, common in terrestrial and marine environments, recently have been derivatized synthetically to enhance their affinity for transuranic metal cations. However, the interactions between these synthetic derivative and adsorbed trace metals have not been characterized. In this paper we compare a natural siderophore, desferrioxamine-B (DFO-B), with its actinide-specific catecholate derivative, N-(2,3-dihydroxy-4-(methylamido)benzoyl)desferrioxamine-B (DFOMTA), as to their effect on the adsorption of Pb(II) and Eu(III) by goethite and boehmite. In the presence of 240 microM DFO-B, a strongly depleting effect on Eu(III) adsorption by goethite and boehmite occurred above pH 6. By contrast, almost total removal of Eu(III) from solution in the neutral to slightly acidic pH range was observed in the presence of either 10 or 100 microM DFOMTA, due primarilyto the formation of metal-DFOMTA precipitates. Addition of DFOMTA caused an increase in Pb(II) adsorption by goethite below pH 5, but a decrease above pH 5, such that the Pb(II) adsorption edge in the presence of DFOMTA strongly resembled the DFOMTA adsorption envelope, which showed a maximum near pH 5 and decreasing adsorption toward lower and higher pH.     

Binding of iron(III) to organic soils: EXAFS spectroscopy and chemical equilibrium modeling

The complexation of iron(III) to soil organic matter is important for the binding of trace metals in natural environments because of competition effects. In this study, we used extended X-ray absorption fine structure (EXAFS) spectroscopy to characterize the binding mode for iron(III) in two soil samples from organic mor layers, one of which was also treated with iron(III). In most cases the EXAFS spectra had three significant contributions, inner-core Fe-O/N interactions at about 2.02(2) A, Fe-C interactions in the second scattering shell at 3.00(4) A, and a mean Fe-Fe distance at 3.37(3) A. One untreated sample showed features typical for iron (hydr)oxides; however, after treatment of iron(III) the EXAFS spectrum was dominated by organically complexed iron. The presence of a Fe-Fe distance in all samples showed that the major part of the organically complexed iron was hydrolyzed, most likely in a mixture of complexes with an inner core of (O5Fe)2O and (O5Fe)3O. These results were used to constrain a model for metal-humic complexation, the Stockholm Humic Model (SHM). The model was able to describe iron(III) binding verywell at low pH considering only one dimeric iron(III)-humic complex. The competition effect on trace metals was also well described.