Macromolecular imidazole-tenside conjugates with carbamate linkage

Polyethylene glycol tert-octylphenyl ether and polyoxyethylenesorbitan trioleate are polydisperse macromolecular detergent molecules, containing a single hydroxyl function, which was transformed by 1,1-carbonyldiimidazole into imidazole-detergent conjugates with a carbamate linkage.     

Isothermal titration calorimetric studies of surfactant interactions with negatively charged, ‘hairy’ latex nanoparticles

Isothermal titration calorimetry (ITC) measurements of the mixture of the cationic surfactant cetyl trimethyl ammonium bromide (CTAB) with negatively charged, hairy copolymer latices (poly-(2,3-epoxypropylmethacrylate-co-methacrylic acid) in different ratio) at high water excess indicate a monomer adsorption mechanism of CTAB by the polymer particles. The number of adsorbed CTAB molecules at saturation corresponds approximately to the number of negative elementary charges bound at the surface of the latices. The mixing enthalpy is the sum of demicellization and sorption enthalpies. At 25 °C for CTAB the demicellization enthalpy amounts to 10 kJ/mol, whereas the adsorption enthalpy varies from –7 kJ/mol (surface charge density of the latices =–0.37 C/m²) to +3 kJ/mol (=–0.085 C/m²). The hydrodynamic radius R_H of the latex particles upon titration of cationic detergent and salt (NaBr) decreases by about 2 nm until the onset of aggregation near the isoelectric point. Titration of nonionic or anionic detergents has much less influence on the hydrodynamic radius and produces no measurable adsorption heat. The results are consistent within a model of latex particles with extended negatively charged polymer chains interacting predominantly via Coulombic forces with detergents.     

Water-promoted unprecedented chemoselective nucleophilic substitution reactions of 1,4-quinones with oxygen nucleophiles in aqueous micelles

Unique nucleophilic substitution and addition reactions of nitrogen and sulfur nucleophiles with 1,4-quinones in aqueous suspension with amines and thiols have recently been demonstrated by us.² However, the reactivity of oxygen nucleophiles toward nucleophilic substitution compared to nitrogen and sulfur nucleophiles ‘on water’ is not facile. An unprecedented economical, green methodology approach using ordinary laundry detergent (LD; washing powder, 0.5 mol %, reusable)/SDS as surfactant ‘in water’ for nucleophilic substitution by oxygen nucleophiles in 1,4-quinones in excellent yields has been demonstrated.     

Multiple response optimization for Cu, Fe and Pb determination in naphtha by graphite furnace atomic absorption spectrometry with sample injection as detergent emulsion

The present paper reports the optimization for Cu, Fe and Pb determination in naphtha by graphite furnace atomic absorption spectrometry (GF AAS) employing a strategy based on the injection of the samples as detergent emulsions. The method was optimized in relation to the experimental conditions for the emulsion formation and taking into account that the three analytes (Cu, Fe and Pb) should be measured in the same emulsion. The optimization was performed in a multivariate way by employing a three-variable Doehlert design and a multiple response strategy. For this purpose, the individual responses of the three analytes were combined, yielding a global response that was employed as a dependent variable. The three factors related to the optimization process were: the concentration of HNO₃, the concentration of the emulsifier agent (Triton X-100 or Triton X-114) in aqueous solution used to emulsify the sample and the volume of solution. At optimum conditions, it was possible to obtain satisfactory results with an emulsion formed by mixing 4 mL of the samples with 1 mL of a 4.7% w/v Triton X-100 solution prepared in 10% v/v HNO₃ medium. The resulting emulsion was stable for 250 min, at least, and provided enough sensitivity to determine the three analytes in the five samples tested. A recovery test was performed to evaluate the accuracy of the optimized procedure and recovery rates, in the range of 88-105%; 94-118% and 95-120%, were verified for Cu, Fe and Pb, respectively.     

Evaluating and selecting the supplier in detergent production industry using hierarchical fuzzy TOPSIS

Supply chain management has increasingly attracted attention as a systematic approach to integrate the supply chain in order to planning and controlling the materials and information from suppliers to customers. One of the most important issues in supply chain management is selection of the appropriate supplier which has significant effect on purchasing cost decrease and increase in the organization’s competition ability. Selection of the best supplier is naturally complex with no definite structure, and dependent on the type of suppliers’ activity. In the process of decision making about suppliers and many qualitative and quantitative performance indicators such as quality, price, flexibility, and due date should be considered. Then, the supplier selection problem is a multi-criteria decision making problem where numerous methods have been proposed to solve this problem so far. In the current paper, four suppliers of imported raw material “Tripolyphosphate (TPP)” (primary material to produce the detergent powder with a case study in Iran) are evaluated based on 25 effective criteria using the hierarchical fuzzy TOPSIS (HFTOPSIS) approach.     

Thermochromatium tepidum外周捕光天线蛋白LH2在脂质体及表面活性剂胶束中的光谱性质

采用动态光散射、透射电子显微镜、紫外-可见吸收光谱和拉曼光谱对比研究了处于表面活性剂胶束和脂质体磷脂双分子层中的Thermochromatium(Tch.)tepidum LH2的光谱响应.结果表明,与在表面活性剂胶束中相比,双分子层脂膜中LH2的Spirilloxanthin(一种含有13个共轭双键的类胡萝卜素)构象有明显差异;表面活性剂及磷脂分子端基的荷电状态对B850-Qy吸收谱有显著影响;Ca2+结合导致B850 Qy吸收谱带红移和增色,而H+结合则使该吸收谱带蓝移和减色.对LH2脱辅基蛋白氨基酸序列的分析结果表明,Ca2+和H+的结合位点可能位于α脱辅基蛋白的C-端一侧.B850 Qy吸收谱带对Ca2+和H+的响应特性可能与Tch.tepidum适应其生存环境的能力有关.     

Nonionic surfactant-selective electrode and its application for determination in real solutions

A liquid membrane nonionic surfactant sensitive electrode has been prepared, based on a new barium pseudocationic complex of a highly ethoxylated fatty alcohol polyglycol ether and tetraphenylborate as sensing material. The complex has been incorporated into the plasticized PVC-membrane and used as sensing material.The electrode exhibited positive linear non-Nernstian response toward different nonionic surfactants and sub-Nernstian response toward tetraphenylborate with the lower detection limit of 3.3 × 10⁻⁷ mol dm⁻³ in barium chloride solution.The interfering effect of some alkaline, alkaline earth, and heavy metal cations, has been demonstrated by displaying their calibration curves compared with that of Triton X-100.The electrode has been used as an end-point indicator for potentiometric titration of analytical and technical grade polyethoxylated nonionic surfactants, modelled detergent products, and commercial detergents.     

Synthesis and characterization of Al doped δ-laminar crystal sodium silicate

An modified laminar crystal sodium silicate(Al-SKS-6)was synthesized by spray drying and high temperature crystallization using sodium silicate as silicon source,Al atom as inorganic source and hexadecyltrimethy ammomum bromide(CTMAB)as the structure template.The hydrothermal stability of product was at least 1 h.The synthesized material was characterized by XRD and SEM.The results indicated that shape and intensity of XRD diffraction peak at 20 took changes.but raw material δ phase crystal form kept unchanged.and assured high Ca2+ and Mg2+ binding capacity of the products.The Ca2+ and Mg2+ binding capacity of product is up to 380 mg Ca/g and 410mg Mg/g respectively.It was found that the hole of product became smaller and appeared rod structure based on SEM. The hydrothermal stability was increased due to the pillaring of A1 atom.     

Rationalizing the membrane interactions of cationic amphipathic antimicrobial peptides by their molecular shape

Biophysical and structural studies of cationic amphipathic antimicrobial peptides have revealed new mechanistic details concerning their membrane interactions. In interfacial environments the peptides adopt amphipathic conformations and the resulting distribution of polar, charged and hydrophobic residues allows them to partition into the bilayer interface. For several helical peptides it was found that their long axis is oriented parallel to the membrane surface, an arrangement which results in considerable perturbations in the packing of the lipid bilayer. Within the molecular shape concept the peptides act as wedge-like structures which impose positive curvature strain on the membrane. As a consequence a wide variety of morphologies are observed of peptide–lipid mixtures which strongly depend on the detailed peptide sequence, the membrane lipid composition, buffer, temperature and other environmental parameters. Therefore, the peptide–lipid systems are best described by phase diagrams, similar to the ones of detergent–lipid mixtures, encompassing on the one extreme regions where the peptide stabilizes the bilayer and on the other extreme regions where membrane lysis occurs. The effects of peptide sequence, membrane penetration depth, lipid composition and membrane surface charge density on membrane-association, -morphology and the resulting phase boundaries are discussed.     

Simultaneous determination of DTPA,EDTA, and NTA by UV–visible spectrometry and HPLC

In this study, UV–visible spectrophotometry (UV–Vis) and high-performance liquid chromatography (HPLC) were used for simultaneous analysis of chelating agents diethylenetriamine pentaacetic acid (DTPA), ethylenediamine tetraacetic acid (EDTA), and nitrilotriacetic acid (NTA), as their metal chelates in dishwashing detergents, natural waters, and pulp mill water. The total amounts of the chelating agents in dishwashing detergents were verified by potentiometric titration with Fe(III) solution. Nickel(II) chelates were determined by UV–Vis and iron(III)chelates by HPLC and titration. Recoveries of DTPA, EDTA, and NTA from a standard mixture of analytes by UV–Vis were 107±7, 101±12 and 94±13%, respectively, and the recovery of the total amount of complexing agents was 99±4%. The limits of detection for DTPA, EDTA, and NTA were 667, 324, and 739 mol L^–1, respectively. In HPLC measurements the optimized mobile phase contained 0.03 mol L^–1 sodium acetate, 0.002 mol L^–1 tetrabutylammonium bromide, and 5% methanol at pH 3.15 and the detection was by UV–Vis detection at 254 nm. All three complexing agents could be separated from each other in a simultaneous analysis in less than 5 min. The limits of detection were 0.34, 0.27, and 0.62 mol L^–1 for DTPA, EDTA, and NTA, respectively. The total amounts of the analytes measured in the dishwashing detergents by the three techniques were found to be highly comparable (ANOVA: F=0.04, P=0.96). R² values were 0.99 for EDTA, 0.99 for NTA, and 0.99 for all the results when UV–Vis and HPLC determinations were compared using regression lines. The UV–Vis and HPLC methods were proved to be viable also for analyses of natural and pulp mill waters. The absence of matrix interferences was verified by the standard addition technique.