偶氮胂-DBS用于光度法测定牛血清白蛋白

在室温下,于pH 2.5的Britton-Robinson缓冲溶液中及非离子表面活性剂OP存在下,牛血清白蛋白(BSA)与偶氮胂-DBS的复合物的最大吸收在514 nm波长处,但显色复合物与试剂空白吸光度之差在370 nm处最大,选择在370 nm处测定,反应迅速完成。非离子表面活性剂OP可提高反应灵敏度及复合物稳定性。乙醇可提高体系灵敏度。BSA的质量范围在0~60.0 mg.L-1范围内符合比耳定律,方法表观摩尔吸光率3ε70 nm=8.58×105L.mol-1.cm-1。方法用于测定血清样品中蛋白质的总量,5次测定值的RSD为0.60%,回收率为98.0%。     

制备参数对高比表面积介孔催化剂La-Co-Zr-O结构与性能的影响

采用双表面活性剂模板(十六烷基三甲基溴化铵和聚乙二醇辛基苯基醚的混合物)分解法制备了不同原子比(n_La+n_Co)/(n_La+n_Co+n_Zr)和不同温度焙烧的系列介孔混合氧化物催化剂La-Co-Zr-O。运用XRD、N₂吸附/脱附、XPS和H₂-TPR等技术对催化剂进行了表征，并以CO和C₃H₈氧化为模型反应，考察了组分配比和焙烧温度等参数对催化剂催化性能的影响。比表面积和孔径测试结果表明，样品具有很高的比表面积(108～266 m²·g^-1)和分布集中的孔径(3.4～3.9 nm)，Zr含量较高的样品比表面积较大。XRD结果表明，样品中的活性组分钴物种主要以Co₃O₄形式存在；XPS和H₂-TPR结果表明，样品中可还原的晶格氧的数量、活动度以及表面钴原子浓度均与催化剂对CO和C₃H₈的氧化性能密切相关。原子比为0.5的样品中，较多的晶格氧易于在相对低温下还原；而原子比为0.7的样品表面钴原子浓度较高，这使得两样品均表现出较高的催化活性。经650 ℃焙烧的样品仍保持较高的比表面积(108 m²·g^-1)和分布集中的介孔孔径(最可几孔径约3.8 nm)，且催化活性下降幅度也很小，表明该系列介孔催化剂具有优良的抗烧结能力和介孔热稳定性。     

混合表面活性剂-铬天青S与铜显色反应研究及应用

在曲拉通X-100(TritonX-100)和乳化剂(OP)存在下,基于Cu2+-铬天青S(CAS)的显色反应,建立了分光光度法测定微量铜的新方法.通过Cu2+与CAS-Triton X-100-OP形成灵敏度较高的多元配合物,来测量铜含量.络合物的最大吸收波长为618nm,表观摩尔吸光系数为ε=6.62×105L·m...     

Optimal media planning for multi-products in segmented market

Promotion is an essential stage of any product life cycle. All firms either concerned with single or multiple products promote their products. Advertising is the most dominated form of promotion for most of the products. Our research focuses on firms which produces a multiple range of products and advertise them using available media options. The budget constraint forms the major restriction. The existing research in media allocation of multiple products ignores the market segmentation and formulates the media plan assuming all segments alike. In this paper we formulate a media planning problem for allocating the available budget in multiple media that are found suitable for the advertising of multiple products considering marketing segmentation aspect of advertising. The objective is to maximize the total reach in all the segments. Goal programming technique is used to solve the problem. A case study is presented to show the real life application of the model.     

OP存在下荧光桃红B-邻菲啰啉光度法测定银的研究及应用

本文研究了在乳化剂OP存在下,银(Ⅰ)与邻菲啰啉,四氯四溴荧光素(荧光桃红B,TCTBF)的显色反应.试验表明乳化剂OP对此显色反应有明显增敏作用,形成配合物的适宜pH范围为3.80-6.00,配合物的最大吸收波长为575nm;表观摩尔吸光系数为9.43×10~4L·mol~(-1)·cm~(-1).银在0—20μg/25ml范围内服从比尔定律,显色体系至少可稳定2h.用该法测定了废水试样中微量的银,所得结果令人满意.     

Fe-CAS-NH4F-OP体系高灵敏度分光光度法测定二氧化硅中微量铁

在ＨＡｃ－ＮＨ４Ａｃ缓冲介质中,当有ＮＨ４Ｆ和乳化剂ＯＰ存在时,Ｆｅ与ＣＡＳ形成络合比为１：３的有色络合物,其最大吸收波长位于６５４．０ｎｍ,表观摩尔吸光系数为１．１８×１０＾５Ｌ·ｍｏｌ＾－１·ｃｍ＾－１,１－２０μｇ Ｆｅ／５０ｍＬ线性关系良好。该法用于二氧化硅中铁的测定,结果令人满意。     

In(Ⅲ)-5-Br-PADAP-OP分光光度法测定锌渣中微量铟

通过对In(Ⅲ)-5＿Br＿PADAP光度分析体系的研究,选择非离子型表面活性剂OP增加显色体系的稳定性。最大吸收波长λmax＝565nm,表观摩尔吸光系数ε＝7.54×104L·mol-1·cm-1,线性范围为0～0.48mg／L。采用甲苯-甲基异丁酮混合溶剂萃取,6mol／LHCl反萃取铟(Ⅲ),消除干扰离子的影响,在水相中测定In(Ⅲ),有效地提高了方法的选择性和准确度。本法应用于测定锌渣中微量铟,获得满意结果。     

Nucleophilic destruction of organophosphate toxins: A computational investigation

Computed reaction enthalpies, free energies, and activation barriers in vacuo are presented for the nucleophilic detoxification of the organophosphorus compounds (H)(HO)P(O)F, (H)(H₃CO)P(O)F and (H₃C)(CH(CH₃)₂O)P(O)F via the reaction R₁OH + (R₂)(R₃O)P(O)F → (R₂)(R₃O)P(O)(OR₁) + HF for a wide variety of R₁OH nucleophiles. Density functional theory at the B3LYP/6-311++G(d,p) computational level was employed for all the calculations. A multi-step Wright-type reaction mechanism [J. B. Wright, W.E. White, J. Mol. Struct. (THEOCHEM) 454 (1998) 259], which proceeds via a proton transfer from the nucleophile to the fluorine atom through the phosphinyl oxygen atom, was consistently found to have a lower activation barrier in the gas-phase than for the corresponding mechanism that operates via a proton transfer from the nucleophile directly to the fluorine atom. Of the nucleophilic agents investigated, peroxybenzoic acid and o-iodosobenzoic acid had the lowest classical activation barrier for the Wright-type mechanism.     

On the performance of a virtual user pairing scheme to efficiently utilize the spectrum of unpaired users in NOMA

This paper evaluates the performance of a virtual user pairing scheme that efficiently utilizes the spectrum of unpaired users in non-orthogonal multiple access (NOMA), termed as VP-NOMA. The scheme aims at utilizing the frequency bands of those users which remain unpaired due to the non-uniform distribution of users in a cellular area. We consider a case where the cell edge users are more than the cell center users, so that complete one-to-one correspondence does not exist between all cell center and cell edge users to be accommodated/paired using conventional NOMA (C-NOMA) user pairing. Thus, some cell edge users remain unpaired, and are served using conventional multiple access (OMA) schemes. In such scenario, VP-NOMA pairs a single cell center user with two or more clustered (closely located) cell edge users over non-overlapping frequency bands, thus enabling the cell center user to efficiently use the frequency bands of these previously unpaired cell edge users. Performance of VP-NOMA in terms of ergodic sum capacity (ESC), outage probability (OP), and outage sum capacity (OSC), is analyzed through comprehensive mathematical derivations and simulations for a generalized system model. Moreover, the mathematical analysis is validated through close concordance between analytical and simulation results of ESC, OP, and OSC.     

Flow Injection Chemiluminescence Determination Of Tetracyclines

Abstract

A fast and simple flow injection chemiluminescence method for the determination of trace amounts of tetracyclines is proposed based on the chemiluminescence of the KMnO₄ - TCs redox reaction in acidic medium in the presence of a sensitizer, OP. The response to the concentration of tetracyclines is linear in the range of 1.00 to 1000 μg mL^?1 with a relative standard deviation < 2.3 % for determination of 50.0 μg mL^?1 of each antibiotic (n = 11). The detection limits for tetracycline, oxytetracycline and chlortetracycline are 0.40, 0.52 and 0.60 μg mL^?1, respectively. The recommended method is suitable for automatic and continuous analysis and has been successfully tested for determination of tetracyclines in commercial formulations. The chemiluminescence intensity was found to be remarkably enhanced when in the presence of OP micellar system; possible reasons for this observed micellar induced enhanced chemiluminescence is given.