bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface and aqueous properties of anionic gemini surfactants having dialkyl amide, carboxyl, and carboxylate groups
Authors: Tsubone Kazuyuki , Ogawa Tomoyasu , Mimura Kunio 
Published: November 2006

AbstractA systematic study of the equilibrium surface properties (in water and in the presence of 10−2 M NaCl) of a novel series of anionic gemini surfactants, (CH2)2[N(COCnH2n+1)CH(COOH)CH2COOH]·2NaOH (GA), where (n+1)=8, 10, 12, 14, and 16, was investigated. The responses of humans to closed patch tests with (CH2)2[N(COC11H23)CH(COOH)−CH2COOH]2·2NaOH (GA‐12) were also investigated. Premicellar self‐aggregation (both in water and 10−2 M NaCl) occurred when the N‐acyl group contained more than 14 carbon atoms, since the critical micelle concentration (CMC) values decreased and the pC20 values increased as (n+1) increased for (n+1) ≤14; the CMC values increased and the pC20 values decreased as (n+1) increased for (n+1)>14, both in water and in 10−2 M NaCl. The absence of a break in the specific conductance‐surfactant molar concentration plots for the GA homologs indicates protonation of the carboxylate group and strong Na+ release during micellization. This is a structural characteristic of the anionic geminis having N‐dialkylamide and carboxylate groups in a molecule. The skin irritation potential of GA‐12 is lower than that of the corresponding “monomer”, C11H23CON(CH3)CH(COOH)CH2(COOH)·NaOH, and the analog, C11H23CON(CH3)CH2COONa·H2O.
Micellization of an anionic gemini surfactant having N,N‐dialkylamide, carboxyl, and carboxylate groups in aqueous NaCl solutions
Authors: Tsubone Kazuyuki , Ghosh Soumen 
Published: November 2006

AbstractThe micellization of an anionic gemini surfactant, (CH2)2[N(COC11H23)CH(CO2H)CH2(CO2H)]2·2NaOH, abbreviated as GA, having N,N‐dialkylamide, carboxyl, and carboxylate groups, in aqueous solutions of NaCl at pH 5.0 was investigated by means of surface tension and of fluorescence, using pyrene as a probe. The l1/l3 vs. log surfactant molar concentration (C) plots showed two values of critical micelle concentration (cmc). Of the two values, the higher cmc value was close to that measured by the surface tension method, meaning that the lower cmc value may be caused by the formation of small, non‐surface‐active soluble premicellar aggregates. Evidence for the existence of these premicellar aggregates includes the fact that the lower of the two cmc values for GA was not observed in the l1/l3 vs. log C plots for (CH2)2[N(COC11H23)CH2CH2CO2Na]2, abbreviated as 212, in 0.001–0.3 M NaCl at pH 11.0, since the only cmc value obtained was close to that from surface tension data. Plots of log molar concentration of Na+ in the solutions vs. log cmc, or Corrin‐Harkins plots, revealed that the lower cmc values decrease with an increase in Na+ concentration, and when [Na+]=1 M, the values reach the decreasing higher cmc value. This means two mechanisms of GA aggregation occured in at the same aqueous solutions of NaCl. In the first one, “monomeric form” → “micelle I” → “micelle II,” and in the second, “monomeric form” → premicelle → micelle II.” The degree of micelle ionization, or β, for the higher cmc values is 0.97 at 10−2 M≦[Na+]≦0.1 M. This large β value indicates that the GA molecules, as a result of the structural characteristic attributable to the simultaneous presence of N,N‐dialkylamide and carboxylate groups in the molecule, may be almost fully dissociated even at the cmc. The β value for the lower cmc is 0.75. This indicates that the existence of a non‐monomeric state at concentrations below the cmc determined from surface tension data, which is additional evidence for the premicellar aggregation.
Quantitative assessment of alkyl chain branching in alcohol‐based surfactants by nuclear magnetic resonance
Authors: van Duynhoven J. P. M. , Leika A. , van der Hoeven P. C. 
Published: November 2006

AbstractSurfactants with branched hydrophobes have gained considerable interest, since these can be used in formulations for laundry cleaning at a wide range of conditions. The claims range from improved dissolution rate to hardness tolerance and stain removing efficacy. In contrast to the historically known heavily branched surfactants, novel branched surfactants are less compromised by increased biodegradability. These properties find their basis in the structural characteristics of the hydrophobe, such as number, position, and type of alkyl chain branches. Our current understanding of structure‐property relations, however, is hampered by the lack of generic methodology needed to obtain structural data on hydrophobe branching. A nuclear magnetic resonance (NMR) approach was developed by which we could obtain a comprehensive set of quantitative hydrophobe branching parameters in alcoholbased surfactants. The13C and1H NMR spin systems of hydrophobe branched species were assigned by means of twodimensional NMR techniques. These assignments allowed the quantitative assessment of these branched species by straight‐forward signal integration in the1H and13C NMR spectra. The quantified NMR data can be used to understand product performance and the biodegradation of surfactants with branched hydrophobes.
The role of surface tension on the residual water content of fabrics
Authors: Carter D. L. , Shah D. O. 
Published: November 2006

AbstractCotton has been shown to hold up to 80% of its initial weight in water due to strong capillary forces after washing. According to the LaPlace equation for capillary rise, the rise is proportional to the surface tension of the air‐liquid interface. The use of a tailored rinse additive has the potential to alter the surface tension of solutions significantly, thus leading to a lower capillary rise. This lower rise can be related to the residual water content in fabrics. The reduction of surface tension lowers the force required to displace liquid inside the capillaries formed by fabric fibers. If the amount of residual water in fabrics can be significantly lowered, the drying time of the fabrics would be decreased as well. We have shown that by reducing the surface tension of solutions, the residual moisture content of fabrics also decreases.
Effect of cefoperazone sodium on the physicochemical properties of surfactants
Authors: Qian Junhong , Gu Jinghua , Xia Jiding 
Published: November 2006

AbstractThe effects of cefoperazone sodium (CS), a pharmaceutical compound, on the critical micelle concentration (CMC) of surfactants with different charges [cetyl trimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Triton X‐100], the cloud point of Triton X‐100, and the Krafft temperatures of SDS and CTAB were studied. The interaction of CS with differently charged surfactants was determined by ultraviolet and fluorescence spectrophotometry. The results show that with increasing CS concentration, the Krafft temperature increases and the CMC decreases in the SDS/H2O system, whereas the opposite results are obtained in the CTAB/H2O system. Both the cloud point and the CMC of Triton X‐100 increase with the addition of CS. The above results are attributed to the different micellar interactions between CS and surfactants with different charges.
Partition of bromophenol blue in toluene/water/sodium bis(2‐ethylhexyl)‐sulfosuccinate water‐in‐oil microemulsions
Authors: Sarma Surashree , Dutta Robin K. 
Published: November 2006

AbstractThe partition of bromophenol blue between oil‐water interfaces and water droplets in water‐in‐oil microemulsions of toluene/water/sodium bis(2‐ethylhexyl)sulfosuccinate was studied by a spectroscopic method at different water fractions and pH. The partition equilibrium constant, Kp, between the two domains decreased considerably with an increase in the water fraction and pH. The decrease in Kp with an increase in the water fraction suggests the retention of more dye molecules in water. The decrease in Kp with an increase in pH has been attributed to a lower tendency of the base form to associate with the anionic oil‐water interface compared with that of the acid form and to an increase in the negative charge density at the oil‐water interface at a higher pH.
Change in the aggregational character of the cationic surfactant cetyl trimethyl ammonium bromide in the presence of o‐ and p‐itrophenolates
Authors: Gokhale G. D. , Hassan P. A. , Samant S. D. 
Published: November 2006

AbstractThe effect of the addition of sodium salts of p‐nitrophenol and o‐nitrophenol on the structural transition of aqueous micellar solutions of the cationic surfactant cetyl trimethyl ammonium bromide (CTAB) was studied by viscosity, 1H nuclear magnetic resonance, and dynamic light scattering measurements. The rapid increase in the relative viscosity of CTAB solutions on the addition of sodium salts of o‐nitrophenol and p‐nitrophenol was due to the transition in micellar shape from spheres to rods. Dynamic light scattering studies indicated a decrease in the diffusion coefficient of the micelles with the addition of p‐nitrophenol. The adsorption and orientation of the salts on the micellar surface and subsequent growth of the micelles was studied by nuclear magnetic resonance.
N‐halosuccinimide‐mercaptoethanol cohalogenation of olefinic fatty methyl esters: Synthesis of β‐halo thioethoxylates
Authors: Singh Sukhprit , Singh Bhupinderpal 
Published: November 2006

AbstractOlefinic fatty methyl esters, undec‐10‐enoate (1), octadec‐Z‐9‐enoate (2), methyl‐12 hydroxy octadec‐Z‐9‐enoate (3), on reaction with N‐halosuccinimides (4,5), that is, N‐bromosuccinimide (4) or N‐chlorosuccinimide (5) and 2‐mercaptoethanol (6) in benzene, gave β‐bromo‐ or β‐chlorothioethoxylates (8–13). β‐Halothioethoxylates so formed were acetylated with acetyl chloride in CH2Cl2 to form the respective acetylated products (20–25).
Mixed micelles of cationic surfactants and bile acid salts in aqueous media
Authors: George Alex , Vora Sambhav , Dogra Arti , Desai Hemangi , Bahadur Pratap 
Published: November 2006

AbstractCritical micelle concentrations of cetyltrimethylammonium‐p‐toluene sulfonate (CTAT) and cetylpyridinium chloride (CPC) with sodium cholate (NaC) and sodium deoxycholate (NaDC) were determined in aqueous solutions by surface tension measurements. Interaction parameters and mole fraction of the components in mixed micelles were estimated using Rubingh's theory. Strong interaction was observed for each mixed system, a common feature shown by anionic‐cationic mixtures. Dramatic effects on the viscosities of these cationic surfactant‐bile salt mixtures were seen, and were markedly dependent upon the counterion of the cationic surfactant and the nature of bile salts. Micelles are small and spherical for cationic surfactants in the presence of NaC. Micelle growth was seen for CPC in the presence of NaDC by an increase in viscosity, but a CTAT solution showed an opposite effect on addition of NaDC. Conductance results supported this view. Different behavior of the two bile salts is explained on the basis of their orientation in cationic micelles.
Surface and thermodynamic studies of N‐alkkyl N‐trimethylsilane ammonium chloride surfactants
Authors: Gad E. A. M. , Badawi A. M. , Zaki M. 
Published: November 2006

AbstractN‐Dodecyl N‐trimethylsilane ammonium chloride, N‐tetradecyl‐N‐trimethylsilane ammonium chloride, N‐hexadecyl‐N‐trimethylsilane ammonium chloride, and N‐octadecyl‐N‐trimethylsilane ammonium chloride were prepared. Surface properties, particularly critical micelle concentration (CMC), effectiveness, maximum surface excess, and minimal surface area, were determined at different concentrations at 20, 35, 50, and 65°C, respectively. From electrical conductivity data, degrees of dissociation and dissociation constants at various concentrations were determined. Free energies, enthalpies, and entropies of micellization and adsorption of the surfactants in aqueous solution were studied.
Modified data handling for rapid low‐field nuclear magnetic resonance characterization of lyotropic liquid crystal composites
Authors: Nadakatti Suresh M. 
Published: November 2006

AbstractA refined nuclear magnetic resonance (NMR) technique was developed to determine the relative volumetric proportions of various phases present in lyotropic liquid crystal (LLC) composites such as soap/detergent bars. Conventionally, the FID (free induction decay, referred to hereafter as Method 1) technique is used for analysis of these systems. This technique is suitable only for composites containing a high concentration of solids and liquid crystals. Method 1 gives erroneous results for composites with a high proportion (>10%) of isotropic liquid phase (L1). The procedure currently practiced (Method 2) for analyzing systems containing >10% L1 entails a considerable amount of experimental and analysis time and involves subjectivity in data analysis. Typically, the phase characterization of the composite using conventional low‐field NMR techniques takes more than 1 h. Furthermore, the hardware and data acquisition features of currently available conventional low‐field NMR spectrometers are inadequate for accurate estimation of relative phase volumes in LLC composites. We developed a modified data‐handling technique (FID—Carr‐Purcell‐Meiboom‐Gill technique, or FIDCPMG technique) which enabled rapid phase characterization of LLC composites and minimized subjectivity while analyzing the data. The standard design of a conventional low‐field NMR spectrometer was upgraded by incorporating a high‐power transmitter and a fast digitizer. The phase composition of four model LLC composites (with L1 percentages varying from 7 to 90%) was determined using FIDCPMG technique and was compared with results from conventional techniques. Phase composition of the LLC composite could be determined in less than 5 min.
Overexpression of acyl‐CoA binding protein and its effects on the flux of free fatty acids in McA‐RH 7777 cells
Authors: Yang Yingying , Pritchard P. Haydn , Bhuiyan Jalal , Seccombe David W. , Moghadasian Mohammed H. 
Published: November 2006

AbstractOverexpression of acyl‐CoA binding protein (ACBP) was induced in a rat hepatoma cell line (McA‐RH 7777) by stable integration of rat ACBP cDNA. The transfected cells (ACBP‐27) had 3.5‐fold higher concentrations of ACBP than control cells (14 vs. 4 ng/μg DNA). Both ACBP‐27 and control cells were cultured in the presence of various concentrations of radiolabeled palmitic acid; and the effects of ACBP on lipogenesis and β‐oxidation were studied. Incubation of the cells with 100 μM palmitic acid resulted in 42% greater incorporation of the fatty acid in ACBP‐27 cells as compared to that in the control cells. This increased incorporation of the fatty acid was observed predominanly in the triglyceride fraction. Higher concentrations of palmitic acid (200 to 400 μM) were associated with a significant decrease in the production of 14CO2 in the ACBP‐27 cell line than in the control cells, while lower concentrations had not effect. Our data suggest a role for ACBP in the partitioning of fatty acids between esterification reactions leading to the formation of neutral lipids and β‐oxidation. ACBP may play a regulatory role by influencing this important branch point in intermediary lipid metabolism.
Synthesis of a novel series of 2‐methylsulfanyl fatty acids and their toxicity on the human K‐562 and U‐937 leukemia cell lines
Authors: Carballeira Néstor M. , Miranda Carlos , Orellano Elsie A. , González Fernando A. 
Published: November 2006

AbstractThe hitherto unknown 2‐methylsulfanyldecanoic acid and 2‐methylsulfanyldodecanoic acid were synthesized from methyl decanoate and methyl dodecanoate, respectively, through the reaction of lithium diisopropylamide and dimethyldisulfide in THF followed by saponification with potassium hydroxide in ethanol. Both α‐methylsulfanylated FA were cytotoxic to the human chronic myelogenous leukemia K‐562 and the human histiocytic lymphoma U‐937 cell lines with EC50 values in the 200–300 μM range, which makes them more cytotoxic to these cell lines than decanoic and/or dodecanoic acid. The cytotoxicity of the studied FA toward K‐562 followed the order 2‐SCH3‐12∶0>2‐SCH3‐10∶0>10∶0>12∶0>2‐OCH3‐12∶0, whereas toward U‐937 the cytotoxicity was 2‐SCH3‐10∶0>2‐SCH3‐12∶0>12∶0>10∶0>2‐OCH3‐12∶0. These results indicate that the α‐methylsulfanyl substitution increases the cytotoxicity of the C10 and C12 FA toward the studied leukemia cell lines.
Synthesis of dihydroperoxides of linoleic and linolenic acids and studies on their transformation to 4‐hydroperoxynonenal
Authors: Schneider Claus , Boeglin William E. , Yin Huiyong , Stec Donald F. , Hachey David L. , Porter Ned A. , Brash Alan R. 
Published: November 2006

AbstractThe cytotoxic aldehydes 4‐hydroxynonenal, 4‐hydroperoxynonenal (4‐HPNE), and 4‐oxononenal are formed during lipid peroxidation via oxidative transformation of the hydroxy or hydroperoxy precursor fatty acids, respectively. The mechanism of the carbon chain cleavage reaction leading to the aldehyde fragments is not known, but Hock‐cleavage of a suitable dihydroperoxide derivative was implicated to account for the fragmentation [Schneider, C., Tallman, K.A., Porter, N.A., and Brash, A.R. (2001) Two Distinct Pathways of Formation of 4‐Hydroxynonenal. Mechanisms of Nonenzymatic Transformation of the 9‐ and 13‐Hydroperoxides of Linoleic Acid to 4‐Hydroxyalkenals, J. Biol. Chem. 275, 20831–20838]. Both 8,13‐ and 10,13‐dihydroperoxyoctadecadienoic acids (diHPODE) could serve as precursors in a Hock‐cleavage leading to 4‐HPNE via two different pathways. Here, we synthesized diastereomeric 9,12‐, 10,12‐, and 10,13‐diHPODE using singlet oxidation of linoleic acid. 8,13‐Dihydroperoxyoctadecatrienoic acid was synthesized by vitamin E‐controlled autoxidation of γ‐linolenic acid followed by reaction with soybean lipoxygenase. The transformation of these potential precursors to 4‐HPNE was studied under conditions of autoxidation, hematin‐, and acid‐catalysis. In contrast to 9‐ or 13‐HPODE, neither of the dihydroperoxides formed 4‐HPNE on autoxidation (lipid film, 37°C), regardless of whether the free acid or the methyl ester derivative was used. Acid treatment of 10,13‐diHPODE led to the expected formation of 4‐HPNE as a significant product, in accord with a Hock‐type cleavage reaction. We conclude that, although the suppression of 4‐H(P)NE formation from monohydroperoxides by α‐tocopherol indicates peroxyl radical reactions in the major route of carbon chain cleavage, the dihydroperoxides previously implicated are not intermediates in the autoxidative transformation of monohydroperoxy fatty acids to 4‐HPNE and related aldehydes.
Analogs of squalene and oxidosqualene inhibit oxidosqualene cyclase of Trypanosoma cruzi expressed in Saccharomyces cerevisiae
Authors: Oliaro‐Bosso Simonetta , Ceruti Maurizio , Balliano Gianni , Milla Paola , Rocco Flavio , Viola Franca 
Published: November 2006

AbstractRecently, a number of inhibitors of the enzyme oxidosqualene cyclase (OSC; EC 5.4.99.7), a key enzyme in sterol biosynthesis, were shown to inhibit in mammalian cells the multiplication of Trypanosoma cruzi, the parasite agent of Chagas’ disease. The gene coding for the OSC of T. cruzi has been cloned and expressed in Saccharomyces cerevisiae. The expression in yeast cells could be a safe and easy model for studying the activity and the selectivity of the potential inhibitors of T. cruzi OSC. Using a homogenate of S. cerevisiae cells expressing T. cruzi OSC, we have tested 19 inhibitors: aza, methylidene, vinyl sulfide, and conjugated vinyl sulfide derivatives of oxidosqualene and squalene, selected as representative of different classes of substrate analog inhibitors of OSC. The IC50 values of inhibition (the compound concentration at which the enzyme is inhibited by 50%) are compared with the values obtained using OSC of pig liver and S. cerevisiae. Many inhibitors of pig liver and S. cerevisiae OSC show comparable IC50 for T. cruzi OSC, but some phenylthiovinyl derivatives are 10–100 times more effective on the T. cruzi enzyme than on the pig or S. cerevisiae enzymes. The expression of proteins of pathogenic organisms in yeast seems very promising for preliminary screening of compounds that have potential therapeutic activity.
Fatty acid and hydroxy acid adaptation in three gram‐negative hydrocarbon‐degrading bacteria in relation to carbon source
Authors: Soltani Mohamed , Metzger Pierre , Largeau Claude 
Published: November 2006

AbstractThe lipids of three gram‐negative bacteria, Acineto‐bacter calcoaceticus, Marinobacter aquaeolei, and Pseudomonas oleovorans grown on mineral media supplemented with ammonium acetate or hydrocarbons, were isolated, purified, and their structures determined. Three pools of lipids were isolated according to a sequential procedure: unbound lipids extracted with organic solvents, comprising metabolic lipids and the main part of membrane lipids, OH−‐labile lipids (mainly ester‐bound in the lipopolysaccharides, LPS) and H+‐labile lipids (mainly amidebound in the LPS). Unsaturated FA composition gave evidence for an aerobic desaturation pathway for the synthesis of these acids in A. calcoaceticus and M. aquaeolei, a nonclassic route in gram‐negative bacteria. Surprisingly, both aerobic and anaerobic pathways are operating in the studied strain of P. oleovorans. The increase of the proportion of saturated FA observed for the strain of P. oleovorans grown on light hydrocarbons would increase the temperature transition of the lipids for maintaining the inner membrane fluidity. An opposite phenomenon occurs in A. calcoaceticus and M. aquaeolei grown on solid or highly viscous C19 hydrocarbons. The increases of FA<C18 when the bacteria were grown on n‐nonadecane, or of iso‐FA in cultures on iso‐nonadecane would decrease the transition temperature of the lipids, to maintain the fluidity of the inner membranes. Moreover, P. oleovorans grown on hydrocarbons greatly decreases the proportion of β‐hydroxy acids of LPS, thus likely maintaining the physical properties of the outer membrane. By contrast, no dramatic change in hydroxy acid composition occurred in the other two bacteria.
Influence of the processing route on microstructure and mechanical properties of the polycrystalline NiAl
Authors: DYMEK S. , WITCZAK Z. , DOLLAR M. 
Published: November 2006

SummaryThe influence of grain refinement on the mechanical properties of differently processed NiAl was presented. Five NiAl near‐stoichiometric alloys were investigated, three conventionally cast and two sintered from powders (fine‐grained powder made by mechanical alloying and nanopowder made by gas condensation). The mechanically alloyed and cast materials were hot extruded at different conditions to obtain diverse grain sizes. The nanomaterial was synthesized in inert gas condensation and then compacted at 1.4 GPa at 300 °C. It was shown that the ductility and strength can be directly controlled by appropriate texture and grain refinement.
New methods of track membrane treatment in the preparation of samples for further observation with scanning electron microscopy
Authors: ORELOVITCH O. L. , APEL P. YU. , SARTOWSKA B. 
Published: November 2006

SummaryTrack membranes are porous systems consisting of a polymer foil with thin channels (i.e. pores) piercing it from surface to surface. The creation of non‐cylindrical pores in a track membrane is important for the optimization of membrane characteristics, i.e. the highest productivity at the required selectivity. A new method of cleavage preparation (the irradiation of track membrane samples with accelerated electrons) for the observation of channel shapes directly in the membrane cross‐sections is presented. Diagrams showing the tensile and burst strengths as a function of the irradiation dose, and images of surfaces and cleavages of track membrane samples are presented in this work. The changes in the pore sizes and shapes along the channel were clearly seen. These results can be used for the optimization of track membrane production.