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Effect of Cationic Micelles on the Kinetics of Interaction of [Cr(Ⅲ)-Gly-Gly]^2＋ with Ninhydrin

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物理化学学报 2008年第12期24卷 2207-2213页

作者： AKRAM Mohd ZAIDI Neelam Hazoor kabir-ud-din Department of Chemistry Aligarh Muslim University Aligarh-202002 India

The effect of cationic micelles of cetyltrimethylammonium bromide (CTAB) on the interaction of chromium dipeptide complex ([Cr(Ⅲ)-Gly-Gly]2+) with ninhydrin under varying conditions has been investigated. The rates of the reaction were determined in both water and surfactant micelles in the absence and presence of various organic and inorganic salts at 70 ℃ and pH 5.0. The reaction followed first- and fractional-order kinetics with respect to [Cr(Ⅲ)- Gly-Gly2+] and [ninhydrin]. Increase in the total concentration of CTAB from 0 to 40×10-3 mol·dm-3 resulted in an increase in the pseudo-first-order rate constant (kψ) by a factor of ca 3. Quantitative kinetic analysis of kψ-[CTAB] data was performed on the basis of the pseudo-phase model of the micelles. As added salts induce structural changes in micellar systems that may modify the substrate-surfactant interactions, the effect of some inorganic (NaBr, NaCl, Na2SO4) and organic (NaBenz, NaSal, NaTos) salts on the rate was also explored. It was found that the tightly bound counterions (derived from organic salts) were the most effective.

关键词：阳离子胶束动力学相互作用甘氨酸甘氨酸茚三酮

Micelle Catalyzed Oxidation of D-Mannose by Cerium (IV) in Sulfuric Acid

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物理化学学报 2008年第5期24卷 810-816页

作者： kabir-ud-din ALI Mohd. Sajid KHAN Zaheer Chemistry Department Aligarh Muslim University Aligarh 202002 UP India Chemistry Department Jamia Millia Islamia Jamia Nagar New Delhi 110025 India

Kinetics of D-mannose oxidation by cerium (IV) was studied in a sulfuric acid medium at 40 ℃ both in absence and presence of ionic micelles. In both cases, the rate of the reaction was first-order in D-mannose and in cerium (IV), which decreased with increasing [H2SO4]. This suggested that the redox reaction followed the same mechanism. The reaction proceeded through formation of an intermediate complex, which was proved by kinetic method. The complex underwent slow unimolecular decomposition to a free radical that reacted with cerium (IV) to afford the product. The catalytic role of cationic cetyltrimethylammonium bromide (CTAB) micelles was best explained by the Menger-Portnoy model. The study of the effect of CTAB also indicated that a negatively charged species was reactive form of cerium (IV). From the kinetic data, micelle-cerium (IV) binding and rate constants in micellar medium were evaluated. The anionic micelle of sodium dodecyl sulfate plays no catalytic role. The oxidation has the rate expression: -d[Ce(IV)]= k1Kc1[D-mannose][Ce(IV)]dt Different activation parameters for micelle catalyzed and uncatalyzed paths were also calculated and discussed.

关键词：甘露糖胶束催化剂硫磺酸化学分析

Limits of Depth: Over-Smoothing and Over-Squashing in GNNs

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Big Data Mining and Analytics 2024年第1期7卷 205-216页

作者： Aafaq Mohi ud din Shaima Qureshi Department of Computer Science and Engineering National Institute of Technology SrinagarSrinagar 190006India

Graph Neural Networks(GNNs)have become a widely used tool for learning and analyzing data on graph structures,largely due to their ability to preserve graph structure and properties via graph representation ***,the effect of depth on the performance of GNNs,particularly isotropic and anisotropic models,remains an active area of *** study presents a comprehensive exploration of the impact of depth on GNNs,with a focus on the phenomena of over-smoothing and the bottleneck effect in deep graph neural *** research investigates the tradeoff between depth and performance,revealing that increasing depth can lead to over-smoothing and a decrease in performance due to the bottleneck *** also examine the impact of node degrees on classification accuracy,finding that nodes with low degrees can pose challenges for accurate *** experiments use several benchmark datasets and a range of evaluation metrics to compare isotropic and anisotropic GNNs of varying depths,also explore the scalability of these *** findings provide valuable insights into the design of deep GNNs and offer potential avenues for future research to improve their performance.

关键词： Graph Neural Networks(GNNs) learning on graphs over-smoothing over-squashing isotropic-GNNs anisotropic-GNNs

菲和芴在等摩尔双表面活性剂/常规表面活性剂混合物中的溶解性(英文)

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Chinese Journal of Chemical Engineering 2014年第9期22卷 1009-1015页

作者： Huma Siddiqui Mohammad Kamil Manorama Panda kabir-ud-din Department of Petroleum Studies Aligarh Muslim University Department of Chemistry Aligarh Muslim University

This study deals with the enhanced solubilization of polycyclic aromatic hydrocarbons(PAHs) such as phenanthrene(PHE) and fluorene(FLR) in a pure cationic gemini(G6) and three conventional surfactants [polyethylene glycol dodecyl ether(Brij35), cetyltrimethyl ammonium bromide(CTAB) and sodium lauryl sulfate(SDS)] as well as in their equimolar binary combinations(G6-Brij35, G6-CTAB and G6-SDS). Their solubilization efficiency toward PHE and FLR has been quantified in terms of the molar solubilization ratio(MSR) and the micelle–water partition coefficient(Km). The ideality/nonideality of the mixed micelles is discussed with the help of Clint,Rubingh and Rosen's approaches. These theories determine the deviation of experimental critical micelle concentration(CMC) values from ideal critical micelle concentration, which was measured by evaluating the interaction parameters(βmand βσ). Negative values of βmwere observed in all the equimolar binary systems, which show synergism in the mixed micelles. Whereas at air/liquid interface synergism was observed in the systems G6-CTAB and G6-Brij35; G6-SDS exhibited an antagonistic effect. The order of MSR and Kmwas G6-CTAB N G6-Brij35 N G6-SDS for phenanthrene as well as for fluorene.

关键词：表面活性剂增溶作用摩尔双子十六烷基三甲基溴化铵混合物临界胶束浓度十二烷基硫酸钠

TX-114+TBAB体系中非电解质对CP的影响(英文)

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物理化学学报 2008年第7期24卷 1180-1184页

作者： kabir-ud-din KHATOON Suraiya NAQVI Andleeb Z Department of Chemistry Aligarh Muslim University

The effects of nonelectrolytes (ureas, amino acids, sugars) on the cloud point (CP) of nonionic surfactant Triton X-114 (TX-114) and tetra-n-butylammonium bromide (TBAB) system were studied. Ureas as well as thioureas increased the CP. Behaviors of amino acids depended upon their nature. Nonpolar and uncharged polar amino acids were less effective in changing the CP. However, tryptophan and phenylalanine increased the CP sharply. Acidic amino acid (aspartic acid) and sugars decreased the CP. The results were explained in terms of their effect on water structure. Amino acids got solubilized either in the micellar interior or in the bulk phase.

关键词：非电解质氨基酸化学分析浊点

水溶液中两亲药物盐酸异丙嗪-表面活性剂体系的胶束化行为(英文)

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物理化学学报 2011年第8期27卷 1900-1906页

作者： kabir-ud-din KHAN Abbul Bashar NAQVI Andleeb Z. Department of Chemistry Aligarh Muslim University

The behavior of the mixed amphiphilic drug promethazine hydrochloride(PMT) and cationic as well as nonionic surfactants was studied by *** cmc values of the PMT-surfactant systems decrease at a surfactant mole fraction of 0.1 and it then becomes *** critical micelle concentration(cmc) values are lower than the ideal cmc(cmc*) values for PMT/TX-100,PMT/TX-114,PMT/Tween 20,and PMT/Tween 60 *** the PMT/Tween 40,PMT/Tween 80,PMT/CPC,and PMT/CPB systems the cmc values are close to the cmc* *** indicates that PMT forms mixed micelles with these surfactants by attractive *** surface excess(Γmax) decreases in the presence of *** rigid structure of the drug makes adsorption easier and the contribution of the surfactant at the interface *** interaction parameters βm(for the mixed micelles) and βσ(for the mixed monolayer) are negative indicating attraction among the mixed components.

关键词：《物理化学学报》期刊摘要编辑部

不同浓度和温度时无机盐和尿素对抗抑郁剂药物丙咪嗪盐酸盐的胶束化行为的影响(英文)

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物理化学学报 2012年第4期28卷 885-891页

作者： kabir-ud-din RUB Malik Abdul NAQVI Andleeb Z. Department of Chemistry Aligarh Muslim UniversityAligarh 202002India

In the present study we report the micellization behavior of imipramine hydrochloride(IMP)in absence and presence of different concentrations of inorganic salts(LiCl,NaF,NaCl,NaBr,and KCl)and ureas(urea and thiourea)over the temperature range from 288.15 to 303.15 *** critical micellization concentrations(cmc)of drug and drug+additive systems were determined by conductometric technique. With increasing temperature the cmc first increases then *** cmc values were obtained at 293.15 K with or without *** presence of inorganic salts the cmc value decreases which is explained on the basis of nature and ion size of the added *** and thiourea also decrease the cmc at low concentrations(0.2 mmo·lL -1 urea and 0.1 mmo·lL -1 thiourea),but,at higher concentrations,increase in cmc is *** related thermodynamic parameters are also evaluated and discussed.

关键词：摘要编辑部编辑工作读者

混合胶束中Gemini阳离子表面活性剂14-s-14与常规表面活性剂的协同作用:连接臂及反离子效应(英文)

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物理化学学报 2010年第6期26卷 1565-1569页

作者： AZUM Naved NAQVI Andleeb Z. AKRAM Mohd. kabir-ud-din Department of Chemistry Aligarh Muslim University

The mixed micelle formation of binary cationic 14-s-14 gemini with conventional single chain surfactants was studied by conductivity *** critical micelle concentration(cmc) and the degree of counterion binding values(g) of the binary systems were *** results were analyzed by applying regular solution theory(RST) to calculate micellar compositions(X),activity coefficients(f1,f2),and the interaction parameters(β).The synergistic interactions of all the investigated cationic gemini+conventional surfactant combinations were found to be dependent upon the length of hydrophobic spacer of the gemini *** excess Gibbs free energy of mixing was evaluated,and it indicated relatively more stable mixed micelles for the binary combinations.

关键词：物理化学理论研究摘要

Fabrication of MXene-Bi_(2)WO_(6)heterojunction by Bi_(2)Ti_(2)O_(7)hinge for extraordinary LED-light-driven photocatalytic performance

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Nano Research 2024年第6期17卷 4729-4736页

作者： Zhiwen Li Liangliang Xu Zaheer ud din Babar Ali Raza Yifei Zhang Xinrui Gu Yu-Xin Miao Zhen Zhao Gao Li Institute of Catalysis for Energy and Environment College of Chemistry and Chemical EngineeringShenyang Normal UniversityShenyang 110034China State Key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China Scuola Superiore Meridionale(SSM) University of Naples Federico IILargo S.Marcellino1080138Italy Department of Chemical and Biomolecular Engineering Korea Advanced Institute of Science and Technology(KAIST)Daejeon 34141Republic of Korea University of Chinese Academy of Sciences Beijing 100049China

Heterojunction composites with intimate interfaces can shorten the diffusion distance,which leads to a shorter path for photogenerated carriers,thereby increasing photocatalytic ***,we report the fabrication of Ti_(3)C_(2)-Bi_(2)WO_(6)(TC-BW)heterojunctions hinged by Bi_(2)Ti_(2)O_(7)joints via an in situ hydrothermal reaction of Ti_(3)C_(2)in the presence of Na_(2)WO_(4)and Bi(NO_(3))_(3).The TC-BW was characterized using X-ray diffraction(XRD),scanning transmission electron microscopy(STEM),and Raman ***-BW showed superior photocatalytic activity(productivity over 15TC-WB reaches up to 5.0 mmolreacted BA·gcat.^(−1)·h^(−1))in the oxidation of benzyl alcohol using light-emitting diode(LED)light,arising from the surface defects and intimate heterojunction interface between the Ti_(3)C_(2)MXene and Bi_(2)WO_(6)***-BW heterojunctions provide an enhanced separation efficiency of photogenerated charges,which in turn yields superior photocatalytic ***,it is well substantiated by density functional theory(DFT)*** summary,this study elucidates the preparation of heterojunction composites with intimate interfaces for highly efficient photooxidation.

关键词： MXene-Bi_(2)WO_(6) heterojunction LED-light-driven photocatalysis Bi_(2)Ti_(2)O_(7) photooxidation