bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tunable topographical cellulose matrices for electro-optical liquid crystal cells
Authors: Costa I. , Almeida P. , Filip D. , Figueirinhas J. , Godinho M. 
Published: November 2006

AbstractIn this work we have used acetoxypropylcellulose (APC) to produce free standing solid films (∼60 μm) that were used for assembling electro-optical devices. Thin films were obtained from concentrated lyotropic solutions of cellulose derivatives. Induced by the cast and shearing preparation conditions wrinkles and band textures can be observed in their free-surface plane. In order to eliminate and control these textures we used a process similar to that introducted in literature [1] which consists of storing the films in the same solvent-vapour atmosphere as the solution system. Lyotropic APC liquid crystalline solutions in dymethylacetamide (DMA) with crosslinker were prepared, thin films were obtained by using a shear/casting technique and stored in the solvent-vapour atmosphere until a planar structure was achieved. The dried crosslinked films were analyzed by optical polarised microscopy (POM) and scanning electron microscopy (SEM). The films with different topographies were used to produce optical cells composed by the cellulose derivative film covered on both free surfaces by a layer of the nematic liquid crystal E7 and placed between two transparent conducting substrates. The electro-optical properties of these cells were obtained.
Microbial aspects of linear alkylbenzene sulfonate degradation in coastal water
Authors: Vives‐Rego J. , López‐Amorós R. , García M. T. , Comas J. , Sánchez‐Leal J. 
Published: November 2006

AbstractViable and total bacteria were determined during linear alkylbenzene sulfonate (LAS) degradation in coastal seawater. Viable bacteria were determined by plate counts on marine agar media, while total bacteria were determined by flow cytometry after SYTO‐13 staining. LAS degradation was monitored by high‐performance liquid chromatography analysis. Seawater samples with LAS at 5 mg/L, incubated in the laboratory (20°C, 100 rpm, 30 d), showed in most cases a similar evolution in bacterioplankton abundance over time, characterized by three phases: (i) a progressive increase in bacterial density; (ii) a later decrease; and (iii) a fluctuating stationary phase. Bacterioplankton degraded the LAS by growing to populations with a high percentage of viable bacteria. The bacteria were rapidly grazed by protozoa, preventing anomalous high bacterial growth and ensuring the later channeling of LAS carbon to upper trophic levels.
Aquatic toxicity—Are surfactant properties relevant?
Authors: Roberts D. W. 
Published: November 2006

AbstractThere are two potential approaches for quantitative structure‐activity relationships modeling of aquatic toxicity of surfactants. One is to try to relate toxicity to parameters describing the surfactant properties, which can be measured or calculated. The other approach is to try to apply to surfactants parameters such as log P (P=octanol/water partition coefficient), which can also be used to relate toxicity to structure for nonsurfactants. This paper compares the two approaches and presents new data supporting the second approach as the more mechanistically relevant. Further refinements in the calculation method for log P are presented.
Lipid soil removal from cotton fabric after mercerization and carboxymethylation finishing
Authors: Obendorf S. Kay , Borsa Judit 
Published: November 2006

AbstractSoiling and soil removal from cotton fabrics that had been chemically modified by mercerization and carboxymethylation were studied using electron microscopy and radiotracer techniques. The distribution of lard soil in specimens before and after laudering was determined by means of chemical tagging with osmium tetroxide. Both the chemical and physical changes of the cotton resulted in differences in soiling and soil removal of lipid soil. Mercerization and carboxymethylation of cotton swell the cotton fiber, decrease the crenulation and the lumen, and smooth the fiber surface. These finishes also increase the pore volume and thus the chemical accessibility of the fibrillar structure. In addition, carboxymethylation causes changes in the chemistry of the fiber by increasing the carboxyl group content. These structural changes reduce the amount of soil deposited in the lumen of the fiber, particularly for the carboxymethylated cotton. They also increase soil removal from the crenulation and the interfiber spaces in the yarn bundle. Soil removal from fiber surfaces and from within the fiber—both lumen and secondary wall—was highest for the carboxymethylated cotton, and mercerization also enhanced lipid soil removal. The results of this experiment indicate that chemical accessibility and hydrophilicity of the fiber structure influence both soil deposition and soil removal of lipid soils. Soil removal of these modified cottons is enhanced by multiple mechanisms: (i) the decrease in small crevices and the crenulation or small capillary along the fiber, (ii) the increase in pore volume that enhances chemical accessibility and thus detergency within the fiber structure, (iii) the increase in hydrophilicity that enhances soil removal from the surface by the roll‐up mechanism, (iv) the increase of mechanical action due to enhanced swelling of the carboxymethylated cotton, and (v) the reduction of soil redeposition on carboxymethylated surfaces.
Surface interaction of quaternary amines with hair
Authors: Beard B. C. , Hare J. 
Published: November 2006

AbstractSurface analysis by X‐ray photoelectron spectroscopy (XPS) has shown specific 1∶1 (ionic) interaction between cationic alkyl quaternary surfactant molecules and the anionic sulfonate groups present on the hair surface. The primary driving force for the adsorption of alkyl quaternary amine molecules to the surface of the hair from aqueous solution is the ionic interaction between quaternary groups and the surface SO3− on the hair. Cationic quaternary molecules incorporating ester and alcohol functionalities (ester quats) demonstrate a lower number of surface quaternary nitrogens per sulfonate group, indicating an altered surface interaction mechanism. For the ester quats, a combination of electrostatic interaction modes exists in addition to the ionic N+/SO3− interaction, specifically, H‐bonding interactions of the −C−O, −C−OH, and −C(O)O− polar groups with SO3− and other polar groups on the hair. Surface coverage of the ester quat is not reduced despite the decrease in ionic interaction at the surface. Both types of molecules orient their alkyl tails toward the surface. Molecular dynamics modeling of the surfactant/hair surface interaction indicates higher adsorption energies due to increased dipolar interactions for ester quat molecules.
Synthesis and properties of N‐(α‐carboxyalkyl)acrylamide telomer‐type surfactants having multihydrocarbon chains
Authors: Yoshimura Tomokazu , Kiridoshi Yasuhiro , Koide Yoshifumi , Shosenji Hideto , Esumi Kunio 
Published: November 2006

AbstractN‐(α‐Carboxyalkyl)acrylamide telomer‐type surfactants (xCn−1AmAc where n is alkyl chain length=6, 8, 10, 12; and x is degree of polymerization=3.3–13.1) were synthesized by the telomerization of monomer (Cn−1AmAc) in the presence of the corresponding alkanethiol as a chain transfer agent and then investigated for their surface‐active properties. xCn−1AmAc telomers lowered the surface tension of aqueous solutions that were at pH 9–10. The critical micelle concentrations (CMC) of the telomers were lower than those of the monomers with the same alkyl chain length, and the CMC values shifted to lower concentrations with both increasing alkyl chain length and polymerization degree. xC9AmAc with x=3.3–6.3 gave the highest efficiencies in lowering the surface tension. The cross‐sectional molecular areas per molecule of xCn−1AmAc telomers were smaller than the values estimated on the assumption that they are assemblies of Cn−1AmAc monomer units. The foaming abilities and the foam stabilities were both in the orders of xC7AmAc>xC9AmAc>xC5AmAc>xC11AmAc. Mixtures of aqueous solutions of xCn−1AmAc telomers and toluene formed oil‐in‐water emulsions. The emulsion‐stabilizing abilities were in the orders of xC7AmAc>xC5AmAc>xC9AmAc=xC11AmAc. The addition of Ca2+ to the mixed solutions of telomers and toluene resulted in formation of water‐in‐oil type emulsions. Thus, the surface‐active properties of the telomers were influenced significantly by the alkyl chain length and the polymerization degree of the telomers. In addition, these properties could be correlated with the hydrophilic‐lipophilic balance (HLB); the highest surface activities were observed by using xCn−1AmAc with HLB of 14–18.
Study of the amination of fatty alcohols catalyzed by Cu−Ni catalysts
Authors: Qiuxiao Li , Gaoyong Zhang , Shaoyi Peng 
Published: November 2006

AbstractAmination of fatty alcohols by hydrogenation and dehydrogenation catalysis is one of the main commercial processes for the production of dimethylalkylamines. The key factor in this process is the preparation of catalysts with high selectivity. A study of amination catalyzed by Cu−Ni catalysts supported on CaCO3 is reported in this paper. Selectivity of the catalysts was adjustable by varying the ratio of Cu to Ni or by adding a third element (Zn or Mg). The promotion of catalyst selectivity was mainly attributable to the effect of the components on the reducibility of Ni2+ in the catalysts. Lower reducibility of Ni2− led to higher catalyst selectivity.
Effect of different additives on the cloud point of a polyethylene oxide‐polypropylene oxide‐polyethylene oxide block copolymer in aqueous solution
Authors: Sharma Rakesh , Bahadur P. 
Published: November 2006

AbstractCloud point studies on aqueous solutions of a polyethylene oxide (PEO)‐polypropylene oxide‐PEO triblock copolymer (Pluronic® L64: EO13PO30EO13, total m.w.=2900, PEO=40%; EO=ethylene oxide; PO=propylene oxide) in the presence of different additives show some interesting features. The effect of various inorganic salts was an increase or decrease in cloud point based on their salting in and salting out action and followed the Hofmeister lyotropic series. Nonelectrolytes and hydrotropes increased the cloud point by influencing water structure. Hydrotropes altered the cloud point of the copolymer at much lower concentrations than inorganic salts. Ionic surfactants produced a marked increase in the cloud point of copolymer solutions. The effect was greater for surfactants with greater hydrophobicity. Alcohols and other organic liquid additives that are infinitely miscible with water increase the cloud point of the copolymer, whereas additives that are partially miscible in water decrease the cloud point.
Micelle ionization degree of anionic gemini surfactant having N,N‐dialkylamide and carboxylate groups
Authors: Tsubone Kazuyuki , Ghosh Soumen 
Published: November 2006

AbstractThe critical micelle concentration (cmc) behavior in aqueous NaCl solutions of the anionic gemini surfactant N,N′‐ethylenebis(sodium N‐dodecanoyl‐β‐alanate), (CH2)2[N‐(COC11H23)CH2CH2(CO2Na)]2 (212), having N,N‐dialkylamide and carboxylate groups in a molecule was investigated to measure the value of micelle ionization degree (α). For comparison, the behavior of sodium N‐dodecanoyl‐N‐methyl‐β‐alanate (SDMA), a monomer corresponding to 212, also was investigated. The α value obtained from the Corrins‐Harkins plot for 212 is 0.97 when [Na+]≤0.025 M and the value for SDMA is 0.51 when [Na[+]≤0.1 M. That the α for 212 is larger than that for SDMA reflects the higher pKa1 value for 212 than the pKa value of SDMA. For 212, when [Na+]≤0.025 M the amount of Na+ released during micellization is so large that the Na+ concentration above the cmc is almost equal to that below the cmc, and therefore 212 nearly behaves as a nonionic surfactant.
Micellar‐improved synthesis of bis‐quaternary ammonium salts by the epichlorohydrin route
Authors: Ricci C. G. , Cabrera M. I. , Luna J. A. , Grau R. J. 
Published: November 2006

AbstractA convenient procedure for the synthesis of bis‐quaternary ammonium salts from long‐chain alkyldimethylamines and epichlorohydrin is studied. An improved preparation of bis‐quaternary ammonium salts from N,N‐dimethyloctylamine, N,N‐dimethyldodecylamine or N,N‐dimethyloleylamine, their amine hydrochlorides, and epichlorohydrin can be achieved by carrying out the reaction in an aqueous micellar medium. The amine hydrochlorides are used as functional surfactants to produce the self‐micellization and solubilization of reactants. The formation of micelles is a necessary condition for a successful quaternization. Comparison of the quaternization performance in ethanol, ethanol/water mixtures, and aqueous micellar medium leads to the conclusion that this micellar‐improved synthesis enables easier and cheaper access to bis‐quaternary ammonium salts by avoiding the formation of the mono‐quaternary ammonium salts as intermediates, and by using water as solvent under mild reaction conditions. Mechanistic aspects of the quaternization reaction in micellized medium are also suggested.
Catalytic destruction of malathion by metallomicelle layers
Authors: Badawi A. M. , Hafiz A. A. , Ibrahim H. A. 
Published: November 2006

AbstractTwo micellized Cu(II) and Fe(III) ion complexes were synthesized and found to possess good catalytic activity in the cleavage of the malathion/dupric (ferric) complex thionate ester. The complexes form metallomicelles, which bind the substrate by coordinating with the thionate sulfur in the malathion (which is chemically similar to the nerve agent sarin). Possible reasons for the rate acceleration include enhanced electrophilicity of the micellized metals, enhanced surface activity, and the recognized ability of cationic micelles to accelerate the cleavage of the thionate ester. The results of kinetic data (half‐life times) for malathion degradation were 13.7 and 8.3 min in the presence of Cu(II) and Fe(III) metallomicelle layers, respectively.
Synthesis and evaluation of polytriethanolamine monooleates for oil‐based muds
Authors: Hafiz A. A. , Abdou M. I. 
Published: November 2006

AbstractNew emulsifiers were developed by esterification of polytriethanolamine based on the dimerization and trimerization of triethanolamine. The dimer and trimer were esterified with oleic acid to prepare monoesters of di‐triethanolamine and tri‐triethanolamine. The synthesized esters were evaluated as water‐in‐oil emulsifiers in oil‐based muds, which are the circulating fluids used in rotary drilling to perform various functions required in the drilling operation, such as control of density, flow, and filtration properties. The dimer and trimer of triethanolamine were also esterified with hydrolyzed cottonseed oil, and the resulting esters were evaluated as commercial emulsifiers for oil‐base muds.
Enhancement of enzymatic catalysis of Bacillus amyloliquefaciens α‐amylase by nonionic surfactant micelles
Authors: Hoshino Eiichi , Tanaka Atsushi 
Published: November 2006

AbstractSome enzymes are considerably more stable when formulated with nonionic surfactants than when formulated with anionic surfactants. The effect of a nonionic surfatant, polyoxyethylene mono‐N‐dodecyl ether (Brij 35; number of units of ethylene oxide moieties, 23), on the kinetic behavior of hydrolysis of amylopectin with Bacillus amyloliquefaciens α‐amylase (BAA) was studied at a temperature of 25°C and a pH of 7.0. The hydrolytic rate was accelerated by the addition of the nonionic surfactant above its critical micelle concentration. Lineweaver‐Burk plots for the enzymatic hydrolysis in the absence and presence of the nonionic surfactant at 0.5 to 2.5% (wt/vol) had linear relationships, and the kinetic parameters, Km and kcat were obtained. The value of kcat was increased with an increased concentration of Brij 35, whereas the Km value was approximately constant. Therefore, the increase in kcat contributed to the acceleration of the apparent hydrolytic rate. The interaction of amylopectin with the surfactant was examined by a surface tension measurement, and the result confirmed the corresponding binding between the substrate and the surfactant. A fluorescence analysis due to tryptophan in BAA suggested that BAA bound to the nonionic micelles. The increase in kcat suggested that hydrolytic catalysis at the micellar pseudophase was more efficient than that at the aqueous pseudophase. The enhancement of the catalytic rate contributed to the effective removal of food stains containing starch when BAA was added with Brij 35 in a laundry detergent washing test.
Fourier‐transform infrared spectra of fatty acid salts—Kinetics of high‐oleic sunflower oil saponification
Authors: Poulenat Gaëlle , Sentenac Sabine , Mouloungui Zéphirin 
Published: November 2006

AbstractSodium, lithium, and calcium soaps obtained by saponification of high‐oleic sunflower oil were studied by Fourier‐transform infrared spectroscopy. Spectra of crude mixtures containing soap, glycerin, residual alkali, and triacylglycerols were compared to those of pure soaps obtained from fatty acids. The infrared spectra of crude soaps showed the same characteristic bands as pure ones. The absorption bands of asymmetric (ω2) and symmetric (ω1) stretching vibrations of the carboxylate group indicated that the metal‐oxygen bonds of these soaps had an ionic character whose strength differed from one cationic counterion to another. Once the characteristic absorption bands of the soaps were assigned, a kinetics study of saponification was performed. Saponification by sodium, anhydrous lithium, and calcium hydroxides was an autocatalytic reaction, characterized by an S‐shaped kinetics curve, whereas saponification by aqueous lithium hydroxide was stoichiometric. The structure of the metal‐oxygen bond played a role in the kinetic mechanisms.
The evolution of anionic surfactant technology to meet the requirements of the laundry detergent industry
Authors: Scheibel Jeffrey J. 
Published: November 2006

AbstractSurfactants are the single most important ingredients in laundry and household cleaning products, comprising from 15 to 40% of the total detergent formulation. They play a key role in the $60 billion detergent market, which is the focus of this review. The past, present, and future trends of mainframe anionic surfactants and the key technological developments for these surfactants are discussed. The focus of this review is on how surfactants are changed (i) to meet changing environmental requirements, (ii) to take advantage of advances in process technology, and (iii) to address changes in consumer habits.
Clouding phenomenon in ionic micellar solutions: Role of the counterion
Authors: Kumar Sanjeev , Khan Ziya Ahmad , Kabir‐ud‐Din  
Published: November 2006

AbstractClouding is rarely observed with ionic surfactants. Herein we report the occurrence of clouding in sodium dodecyl sulfate (SDS, an anionic surfactant) solutions on addition of different symmetrical and unsymmetrical quaternary phosphonium bromides (tetra‐n‐butylphosphonium, tetraphenylphosphonium, and n‐propyltriphenylphosphonium). Cloud point (CP) measurements were made with solutions having different SDS/salt combinations. The nature of the counterion had a crucial role in the occurrence of the phenomenon, whereas substitution of an alkyl chain by a phenyl ring made the salt more effective near ambient temperature. A linear relationship between the SDS and salt concentrations was obtained. It is proposed that both the electrostatic charge and the hydration state of the headgroup region are influenced by counterion addition and that the net charge or volume of the counterion has a key role to play in the overall phenomenon. The effect of the addition of some hydroxy compounds on CP variations in these SDS+salt systems was also studied, and the data were interpreted on the basis of incorporation of these compounds in the micellar headgroup region. The nature of the counterions influenced this incorporation.
The self‐aggregation of sodium perfluorooctanoate in aqueous solution at different temperatures
Authors: González‐Pérez Alfredo , Ruso Juan M. , Prieto Gerardo , Sarmiento Félix 
Published: November 2006

AbstractElectrical conductivities of sodium perfluorooctanoate (SPFO) in aqueous solutions were measured at different temperatures (range 294–328 K). Critical micelle concentrations (CMC) and the degree of ionization (α) of the micelles were derived from such data. The results revealed that temperature dependence of CMC is U‐shaped with a minimum at 316 K. Gibbs free energies, enthalpies, and entropies of micelle formation as a function of temperature were estimated from the CMC and α values using the charged pseudo‐phase separation model. To correlate the enthalpic and entropic contributions, the compensation phenomenon was studied, with a compensation temperature of 309 K and an intercept of −27.7 kJ·mol−1. Apparent molar volumes and adiabatic compressibilities of SPFO were determined from density and ultrasound velocity measurements in the same temperature range as conductivities. Positive deviation from the Debye‐Hückel limiting law of the apparent molar volume in the range of temperatures studied evidenced hydrogen bonding‐type interactions between monomers and the existence of dimers in the premicellar region. With micellization, the apparent molar volumes decrease with rising temperature, indicating that the structure of micelles is looser than that of monomers. The isentropic apparent molar adiabatic compressibilities following micellization were positive, indicating the predominant role of the decrease in hydrophobic hydration in the association process.
Synthesis, characterization, and surface properties of phenylalanine‐glycerol ether surfactants
Authors: Varka E.‐M. , Coutouli‐Argyropoulou E. , Infante M. R. , Pegiadou S. 
Published: November 2006

AbstractA novel homologous series of 1‐N‐l‐phenylalanine‐glycerol ether surfactants was synthesized in satisfactory yieldsviareaction of epichlorohydrin with aliphatic alcohols with alkyl chains of 10–15 carbon atoms. Structural assignment of the new compounds was made on the basis of elemental analysis and spectroscopic data. Critical micelle concentration (CMC), surface tension at the CMC (γCMC), surfactant concentration required to reduce the surface tension of the solvent by 20 mN/m (pC20), and the interfacial area occupied by the surfactant molecules (Amin) were determined from aqueous surface tension measurements using the Wilhelmy plate technique.
Sulfoxidation of fatty acid methyl esters: Conversion and selectivity
Authors: Cohen Leon , Soto Fernando , Pratesi C. , Faccetti L. 
Published: November 2006

AbstractIn this work several batch sulfoxidation reactions of different fatty acid methyl esters, having chain lengths of C12 to C18, in the presence of SO2, O2, and ultraviolet light of 253 nm have been carried out. The average reaction conversion for each methyl ester has been calculated and the selectivity determined by liquid chromatography. The results indicate that conversion increases dramatically with the increase of carbon chain length, whereas selectivity to monosulfonate seems to increase slightly as the chain length increases.