全谱段H点标准加入法研究

改进了Ｈ点标准加入法。这种方法称为“全谱段Ｈ点标准加入法”，当分析物质和干扰物质同时存在于样品中时，这种方法可获得分析物质的无偏差分析浓度，全谱段Ｈ点标准加入法，采用干扰物质吸收光谱图上多个成直线的波长点，以Ｈ点标准加入法和Ｋ比例Ｈ点标准加入法为判据，测定多组分体系，并以水杨酸－对硝基苯甲酸－对氨基苯甲酸的不同混合物为例，对方法进行验证，结果满意，并采用先进的Ｗｉｎｄｏｗｓ应用程序设计语言Ｖｉｓｕａｌ Ｂａｓｉｃ４．０设计出具有Ｗｉｎｄｏｗｓ“图形用户界面”特点的应用程度，这使得原本枯燥杂乱的多数据计算，分析工作变得简洁有序并饶有趣味。     

灰色分析体系选择测定研究：I.理论基础和模拟研究

首先运用分析物响应光谱Ｋ－系数对含基体和化学干扰的混合光谱进行分离，求得基体与化学干扰总光谱；进而运用Ｈ点标准加入法，结合基与化学干扰总光谱Ｋ－系数，实现对分析的选择测定，最后通过数据模拟研究了零波长（λ０）和Ｈ点波长（λＨ）的选择方法。     

正交回归多组分标准加入光度法同时测定污水中的铜、镍、镉和锌

1引言多组分同时测定的光度法都依据比耳定律的线性加和原理，所以对实测样品中存在非线性干扰的多组分体系就很难简单处理。利用正交回归多波长光度法，可以引入反映组分间相互影响的交互作用项，并依据多组分标准加入法的原理，给出各波长处吸光度A（λ）与各待测组分浓度Xi（规范变量）间的关系为：均为回归系数。这里及di分别为组分i的浓度，基准浓度及变化间距。采用标准加入法，就是将含有多个待测组分的待测样中，按正交设计加入一定量的标准溶液，测定各试样溶液在一定显色体系中的吸光度。经回归分析求得回归方程中的回归系数。若…     

流动注射—氢化物发生—非色散原子荧光光谱法直接测定海水中的砷（Ⅲ）和砷（

用流动注射－氢化物发生－非色散原子荧光光谱法对海水中Ａｓ（Ⅲ）和Ａｓ（Ⅴ）的直接测定进行了研究,氢化物发生的最佳条件为：ＫＨＢ４溶液浓度为５ｇ．Ｌ＾－１（含ＫＯＨ５ｇ．Ｌ＾－１）,流速１０．０ｍＬ．ｍｉｎ＾－１;样品酸度为１．３ｍｏｌ．Ｌ＾－１ＨＣｌ,流速４．２ｍＬ．ｍｉｎ＾－１。对基体ＮａＣｌ,ＭｇＣｌ２,ＣａＣｌ２,Ｎａ２ＳＯ４以及微量共存金属离子（Ｃｄ,Ｚｎ,Ｐｄ,Ｃｕ）的干扰实验结果表明,基体和微量共存金属离子对Ａｓ（Ⅲ）的测定没有干扰。样品中Ａｓ（Ⅴ）的测定用硫脲进行预还原,通过总量和Ａｓ（Ⅲ）的含量的差减得到Ａｓ（Ⅴ）含量,在优化实验条件下下测量方法的检出限（３σ）为０．０８ｎｇ．ｍＬ＾－１;７次测定的相对标准偏差为０．４８％－１．３０％（８．０ｎｇ．ｍＬ＾－１标准溶液）。标准曲线和标准加入法对海水     

电动胶束色谱中弱酸性化合物的柱上浓缩富集技术的研究

提出一种电动胶束色谱（ＭＥＫＣ）中弱酸性化合物的柱上浓缩富集技术,并得到实验证实。以七种弱酸性巴比妥类药物的ＭＥＫＣ分离为例,考察了样品溶剂中表面活性剂浓度、ｐＨ值和离子强度等对富集作用的影响。表面活性剂浓度,ｐＨ值对富集效应的影响较大。采用低浓度（略高于ＣＭＣ点）表面活性剂、低浓度缓冲液作样品溶剂,调节溶剂ｐＨ值小于待测化合物的ｐＫａ－１,就可以对弱酸性化合物进行柱上富集。采用这种富集技术,可以压缩样品带的宽度从而提高柱效,在此基础上可通过加大进样量提高化合物的检测灵敏度。     

离子色谱法测定氟化物的干扰及其消除

针对离子色谱法与离子选择电极法测定地面水样品中氟化物存在一定偏差的现象,此文较详细地研究了影响测定结果的干扰因素,确证ＣＯ３＾２－,ＨＣＯ３＾－均能产生正干扰,其干扰程度与干扰物质的含量成正比,为消除基体的干扰,可采用标准加入法。     

H点标准加入光度法同时测定葡萄糖和木糖

１引言葡萄糖和木糖是自然界中最常见的两种单糖，其结构和化学性质极为相似，用普通方法很难将其分离和分别测定。本文利用硫酸－苯酚与糖的显色反应，采用Ｈ点标准加入法对葡萄糖和木糖不经分离进行同时测定。本法简便、快速、结果准确，已应用于食用纤维的分析。２方法原理在二元混合物（组分为ｘ和ｙ，浓度为ＣｘＣｙ）体系中，将不同量已知浓度的ｘ分别准确加入到一系列混合体系中，然后分别在λ１和λ２处测量其分析信号Ａ１和Ａ２。其表达式为：Ａ１＝ｋｘ１Ｃｘ＋Ｋｙ１Ｃｙ＋Ｋｘ１Ｃｉｘ（１）Ａ２＝ｋｘ２Ｃｘ＋Ｋｙ２Ｃｙ＋ｋｘ…     

低压离子色谱法测定CeO2产品中微量氟的研究

采用氟碳铈矿为原料冶炼成的稀土氧化物产品中 ,氟含量的测定在检验稀土产品纯度中起着重要的作用。目前此类产品中氟含量的测定主要有二甲酚橙 锆退色法和氟试剂法[1 ] 。而采用低压离子色谱法分析稀土氧化物产品中氟含量还未见报道[2 ,3] 。本文研究用低压离子色谱 (ＬＰＩＣ)法测定稀土ＣｅＯ2 中氟含量。试验证明 ,样品预处理时 ,在ＨＣｌＯ4介质中加入ＡｇＣｌＯ4以消除阴离子干扰 ,并用水蒸气将氟蒸馏出 ,以ＫＯＨ溶液吸收。选择 1 .2ｍｍｏｌ/ＬＮａ2 ＣＯ3作淋洗液 ,ＬＰＩＣ测氟。与氟试剂法 (ＧＢ)作比较分析 ,两种方法测定结果一…     

通用H点标准加入法解析灰色体系

通用H点标准加入法可消除未知干扰影响，测定灰色体系中待测组分含量，给出唯一解。介绍了其原理、算法，并用于定量分析中药制剂中的有效成分，以实验验证了本方法实际应用的可行性及其结果的可靠性。     

萃取分离—苯芴酮分光光度法测定茶叶中锗的含量

对苯芴酮分光光度法测定微量锗时的干扰情况进行了考查，发现在Ｈ３ＰＯ４和ＨＣｌＯ４共存体系中，以ＣＣｌ４萃取Ｇｅ，并在显色测定时加入乙酰丙酮作掩蔽剂，能有效地消除干扰，本实验还对茶叶样品的处理方法进行了比较，灰化法时间短，操作简单，Ｇｅ损失小。     

Application of Pac Ester in Thioester Method for the Synthesis of Cyclopentapeptides

Thioester method for the synthesis of cyclopeptides is improved by using Pac (Pac = phenacyl, CH2COC6Hs) ester as a protecting group of 3-mercaptopropionic acid. The Pac group is easy to be removed from C-terminal with zinc in acetic acid. The protected glycine thioester and peptide thioesters synthesized by the improved method, are easy to be purified, so the final linear peptides are pure enough for the following cyclization. Furthermore, this method is flexible for peptide chain elongation,either from C-termlnal or from N.terminal. So it is an efficient and practical method for synthesis of bioactive peptides. Two N-protected pentapeptide thioesters, Boc-Pro-Tyr-Leu-Ala-GIySCH2CH2COOPac and Boc-Ala-Tyr-Leu-Ala-Gly-SCH2CH2COOPac were synthesized by the improved thloester method.After deprotecting Pac ester with zinc in aqueous acetic acid and Boc group with trifluoroacetic acid in CH2C12, two free pentapeptide tldoesters were obtained. Ag^ -assisted cyclization in acetate buffered solution afforded two cyclic pentapeptides c(Pro-Tyr-Leu-Ala-Gly) and c(Ala-Tyr-Leu-Ala-Gly).Effects of different buffer pH, different Ag^ concentrations, etc. on the cyclization were studied.     

A label-free indicator for tumor cells based on the CH2-stretch ratio

In this paper, we assess the potential of a label-free infrared absorbance based measurement method for determination of the CH(2)-symmetric to CH(2)-antisymmetric stretch ratio, to aid in the detection of the presence of cancer cells and to differentiate between various cancer cells. For this study a normal epithelial kidney cell line, two carcinoma epithelial kidney cell lines, an adult primary human melanocyte cell line, and three human melanoma cell lines were investigated. For the measurements we used a self-designed IR sensor which has the potential to be further developed in a point-of-care instrument. To investigate the mechanism influencing the CH(2)-stretch ratio of mammalian cell membranes, a normal epithelial kidney cell line was exposed to the plasma membrane bound cholesterol reducing agent methyl-β-cyclodextrin. This methodology yielded statistically significant CH(2)-stretch ratio differences between the individual cell lines, normal and tumorous, of both epithelial kidney and melanocyte origin. Measurement results of normal epithelial kidney cells exposed to methyl-β-cyclodextrin indicate that an increase in the CH(2)-stretch ratio arises when there is a decrease in, or redistribution of, the membrane stabilizing agent cholesterol. This study proves that the proposed cell type discrimination method, based on the CH(2)-symmetric to CH(2)-antisymmetric stretch ratio, allows the discrimination between normal and tumor cells. In addition, the method shows high potential for improvement of staging of suspicious tissues.     

Quantum mechanics calculations of the thermodynamically controlled coverage and structure of alkyl monolayers on Si(111) surfaces

The heat of formation, Delta E, for silicon (111) surfaces terminated with increasing densities of the alkyl groups CH3- (methyl), C2H5- (ethyl), (CH3)2CH- (isopropyl), (CH3)3C- (tert-butyl), CH3(CH2)5- (hexyl), CH3(CH2)7- (octyl), and C6H5- (phenyl) was calculated using quantum mechanics (QM) methods, with unalkylated sites being H-terminated. The free energy, Delta G, for the formation of both Si-C and Si-H bonds from Si-Cl model compounds was also calculated using QM, with four separate Si-H formation mechanisms proposed, to give overall Delta G(S) values for the formation of alkylated Si(111) surfaces through a two step chlorination/alkylation method. The data are in good agreement with measurements of the packing densities for alkylated surfaces formed through this technique, for Si-H free energies of formation, Delta G(H), corresponding to a reaction mechanism including the elimination of two H atoms and the formation of a C=C double bond in either unreacted alkyl Grignard groups or tetrahydrofuran solvent.     

Layer‐by‐layer deposition of antimicrobial polymers on cellulosic fibers: a new strategy to develop bioactive textiles

In recent years, there has been an increase of infectious diseases caused by different microorganisms and the development of antibiotic resistance. In this way, the search for new and efficient antibacterial materials is imperative. The main polysaccharides currently used in the biomedical and pharmaceutical domains are chitin and its derivative chitosan (CH) and alginates (ALG). In this study, a simple technique of Layer by Layer (LbL) of applying polycation CH and polyanion ALG was used to prepare CH/ALG multilayers on cotton samples via the electrostatic assembly with success. The CH/ALG cotton samples (functionalized) were investigated for their antibacterial properties towards Staphylococcus aureus and Klebsiella pneumonia using the international standard method JIS L 1902:2002. The antibacterial activity of the functionalized samples was tested in terms of bacteriostatic and bactericidal activity, and results showed that the samples exhibited a bacteriostatic effect on the two bacteria tested, as expected. In addition, samples with five layers (CH/ALG/CH/ALG/CH) were more effective in inhibiting bacterial growth. This new coating for cellulosic fibers is a new strategy and may open new avenues for the development of antimicrobial polymers with potential application in health‐care field. Copyright © 2013 John Wiley & Sons, Ltd.     

Reactions of Laser Ablation-magnesium Plasma with Methanol Clusters

IntroductionReactions of metal ions with neutral molecules orclusters produce a variety of metal complex ions andother new series of cluster ions including cations andanions.The laser ablation-molecular beam(LA-MB)method has marked its relevance in the st…     

Formation of gallaoxetanes: C-O activation of 1,2-epoxybutane by ground-state Ga atoms

(69/71)Ga atoms were reacted with 1,2-epoxybutane and its isotopomers, 1,2-epoxybutane-1,1-d(2) (CH(3)CH(2)CHOCD(2)) and 1,2-epoxybutane-2-d(1) (CH(3)CH(2)CDOCH(2)), under matrix-isolation conditions. The novel gallaoxetanes CH(3)CH(2)CHCH(2)GaO and CH(3)CH(2)CHCH(2)OGa, resulting from the insertion of the metal atom in the C(1)-O and C(2)-O bonds, respectively, of the 1,2-epoxybutane, were detected by EPR spectroscopy. The Ga and H hyperfine interaction (hfi) values of the gallaoxetanes, calculated using a DFT method, were used to help assign the EPR spectra. A third Ga-centered species, detected at 190 K, underwent spectral changes similar to those of the C(2)-O insertion product upon isotopic substitution of the 1,2-epoxybutane. Although the Ga hfi for this species was 36% smaller than that of the C(2)-O insertion product, the values for the H hfi were similar, suggesting that the carrier of the spectrum was the C(2)-O insertion product where Ga was perturbed by the matrix constraints. The alkyl radical CH(3)CH(2)(?CH)CH(2)OGa, resulting from ring-opening at the C(2)-O bond of 1,2-epoxybutane, was observed at temperatures below 150 K. This radical has been implicated in the formation of the C(2)-O insertion product. The unusually small value found for two of the β-hydrogens of the alkyl radical is discussed.     

A method for characterizing adsorption of flowing solutes to microfluidic device surfaces

We present a method for characterizing the adsorption of solutes in microfluidic devices that is sensitive to both long-lived and transient adsorption and can be applied to a variety of realistic device materials, designs, fabrication methods, and operational parameters. We have characterized the adsorption of two highly adsorbing molecules (FITC-labeled bovine serum albumin (BSA) and rhodamine B) and compared these results to two low adsorbing species of similar molecular weights (FITC-labeled dextran and fluorescein). We have also validated our method by demonstrating that two well-known non-fouling strategies [deposition of the polyethylene oxide (PEO)-like surface coating created by radio-frequency glow discharge plasma deposition (RF-GDPD) of tetraethylene glycol dimethyl ether (tetraglyme, CH(3)O(CH(2)CH(2)O)(4)CH(3)), and blocking with unlabeled BSA] eliminate the characteristic BSA adsorption behavior observed otherwise.     

Ab initio molecular dynamics study on the electron capture processes of protonated methane (CH5+)

Electron capture dynamics of protonated methane (CH5(+)) have been investigated by means of a direct ab initio molecular dynamics (MD) method. First, the ground and two low-lying state structures of CH5 (+) with eclipsed Cs , staggered Cs and C2v symmetries were examined as initial geometries in the dynamics calculation. Next, the initial structures of CH5 (+) in the Franck-Condon (FC) region were generated by inclusion of zero point energy and then trajectories were run from the selected points on the assumption of vertical electron capture. Two competing reaction channels were observed: CH5 (+) + e (-)--> CH4 + H (I) and CH5 (+) + e (-) --> CH3 + H2 (II). Channel II occurred only from structures very close to the s- Cs geometry for which two protons with longer C-H distances are electronically equivalent in CH5 (+). These protons have the highest spin density as hydrogen atoms following vertical electron capture of CH5 (+) and are lost as H2. On the other hand, channel I was formed from a wide structural region of CH5 (+). The mechanism of the electron capture dynamics of CH5 is discussed on the basis of the theoretical results.     

Visible light induced CO2 reduction and Rh B decolorization over electrostatic-assembled AgBr/palygorskite

AgBr/palygorskite composite was prepared by an in situ electrostatic adsorption-deposition-precipitation method and characterized by field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), UV-Vis diffuse reflection, and BET surface measurements techniques. The layer negative charge and larger specific surface area of palygorskite, along with the poor cation-exchange ability of tetra-n-butyl ammonium cation (N(CH(2)CH(2)CH(2)CH(3))(4)(+)) due to its larger ion radius, could mainly account for high dispersity of AgBr on the surface of fibrous palygorskite. The rate of Rh B decolorization and CO(2) reduction with H(2) as a proton donor and reductant over AgBr/palygorskite was about three and two times faster than that of the corresponding bare AgBr, respectively. The strategy reported in this work can be easily extended to synthesize other palygorskite-based heterostructure catalysts.     

A kinetic and mechanistic study of the reactions of OH radicals and Cl atoms with 3,3,3-trifluoropropanol under atmospheric conditions

Product distribution studies of the OH radical and Cl atom initiated oxidation of CF3CH2CH2OH in air at 1 atm and 298 +/- 5 K have been carried out in laboratory and outdoor atmospheric simulation chambers in the presence and absence of NOx. The results show that CF3CH2CHO is the only primary product and that the aldehyde is fairly rapidly removed from the system. In the absence of NOx the major degradation product of CF3CH2CHO is CF3CHO, and the combined yields of the two aldehydes formed from CF3CH2CH2OH are close to unity (0.95 +/- 0.05). In the presence of NOx small amounts of CF3CH2C(O)O2NO2 were also observed (<15%). At longer reaction times CF3CHO is removed from the system to give mainly CF2O. The laser photolysis-laser induced fluorescence technique was used to determine values of k(OH + CF3CH2CH2OH) = (0.89 +/- 0.03) x 10(-12) and k(OH + CF3CH2CHO) = (2.96 +/- 0.04) x 10(-12) cm3 molecule(-1) s(-1). A relative rate method has been employed to measure the rate coefficients k(OH + CF3CH2CH2OH) = (1.08 +/- 0.05) x 10(-12), k(OH + C6F13CH2CH2OH) = (0.79 +/- 0.08) x 10(-12), k(Cl + CF3CH2CH2OH) = (22.4 +/- 0.4) x 10(-12), and k(Cl + CF3CH2CHO) = (25.7 +/- 0.4) x 10(-12) cm3 molecule(-1) s(-1). The results from this investigation are discussed in terms of the possible importance of emissions of fluorinated alcohols as a source of fluorinated carboxylic acids in the environment.