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Purpose: Plasma trimethylamine-N-oxide (TMAO) levels have been shown to correlate with increased risk of metabolic diseases including cardiovascular diseases. TMAO exposure predominantly occurs as a consequence of gut microbiota-dependent trimethylamine (TMA) production from dietary substrates including choline, carnitine and betaine, which is then converted to TMAO in the liver. Reducing microbial TMA production is likely to be the most effective and sustainable approach to overcoming TMAO burden in humans. Current models for studying microbial TMA production have numerous weaknesses including the cost and length of human studies, differences in TMA(O) metabolism in animal models and the risk of failing to replicate multi-enzyme/multi-strain pathways when using isolated bacterial strains. The purpose of this research was to investigate TMA production from dietary precursors in an in-vitro model of the human colon. Methods: TMA production from choline, l-carnitine, betaine and γ-butyrobetaine was studied over 24–48 h using an in-vitro human colon model with metabolite quantification performed using LC–MS. Results: Choline was metabolised via the direct choline TMA-lyase route but not the indirect choline–betaine-TMA route, conversion of l-carnitine to TMA was slower than that of choline and involves the formation of the intermediate γ-BB, whereas the Rieske-type monooxygenase/reductase pathway for l-carnitine metabolism to TMA was negligible. The rate of TMA production from precursors was choline > carnitine > betaine > γ-BB. 3,3-Dimethyl-1-butanol (DMB) had no effect on the conversion of choline to TMA. Conclusion: The metabolic routes for microbial TMA production in the colon model are consistent with observations from human studies. Thus, this model is suitable for studying gut microbiota metabolism of TMA and for screening potential therapeutic targets that aim to attenuate TMA production by the gut microbiota. Trial registration number: NCT02653001 (http://www.clinicaltrials.gov), registered 12 Jan 2016. [ABSTRACT FROM AUTHOR]

Wheat straws (WS) were pretreated by a two-step pretreatment for enhanced enzymatic hydrolysis. The raw wheat straw (RWS) was firstly soaked in microwave-assisted NaOH solution at the presence of a mixed solution of H2O2 and hexadecyl trimethyl ammonium chloride (HTAC), and the residue was put into methyl orange (MO) solution to obtain the final substrate for enzymatic hydrolysis. It was interesting to find that the WS after the first step of the pretreatment could effectively remove MO in the second step of the pretreatment with the highest removal efficiency of 98.86% at the MO concentration of 25 mg/L and at the adsorbent-adsorbate ratio of 0.8%. Meanwhile, the enzymatic hydrolysis efficiency of the WS that was pretreated by the two steps was higher than that of the RWS as well as the first-step-pretreated WS. Enzymatic hydrolysis experiment showed that the glucose concentration after 48-h hydrolysis was 4.85 g/L at the solid loading of 5%, compared with the RWS of 0.90 g/L and the first-step-pretreated WS of 4.33 g/L. This suggested that the two-step pretreatment method could not only make WS as a good adsorbent but also a more biodegradable lignocellulosic material. Characterization analysis showed that the specific surface area and the cellulose content of the WS were both increased after the two-step pretreatment, indicating that the pretreatment method was significant to properly utilizing WS as biosorbent and biofuel. Besides, a possible mechanism for the effect of the pretreatment on the WS was proposed. [ABSTRACT FROM AUTHOR]

Abstract: A new method is developed to measure the phase-transition temperatures in artificial phospholipid membranes. This method is based on studying the temperature dependence of dark conductivity and photoconductivity in a symmetric cell with current-conducting indium-tin oxide (ITO) electrodes. Internal electron photoemission into a thin liposome layer is induced by visible and near IR light from the ITO electrodes. This method is applied to study the lyotropic phases in 1,2-dipalmitoyl-rac-glycero-3-phosphocholine (DPPC) and 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) with ethylene glycol (EG) and glycerol (G). The results of time-of-flight measurements are used to calculate the carrier mobilities in liposome vesicles. The measurement results are compared with the results obtained by dc conductometry. We are the first to detect the effect of a positive temperature coefficient of resistivity in a liquid-crystal phase. The proposed method makes it possible to detect the phase transitions in lyotropic liquid-crystal systems and, hence, can be used to create biocompatible drug carriers based on thermosensitive liposomes. [ABSTRACT FROM AUTHOR]

Reaction of 2-chloro-N-(2,2-dichloro-1-cyanovinyl)acetamide with dimethylamine gave 5-(dimethylamino)-2-[(dimethylamino)methyl]-1,3-oxazole-4-carbonitrile, where aliphatic dimethylamino group was regioselectively alkylated with iodomethane. The resulting trimethylammonium salt reacted diastereoselectively with aromatic aldehydes to form new substituted 2-(oxiran-2-yl)-1,3-oxazoles. [ABSTRACT FROM AUTHOR]

The synthesis of high activity TiO-CTAB-SiC composite possessing the microwave absorption capacity has been reported. Herein, the commercial Silicon carbide (SiC) particles were used as the microwave absorbent and supporter. TiO nanopowders were loaded on the surface of SiC modified by hexadecyl trimethyl ammonium bromide (CTAB) via the hydrothermal route. The as-prepared TiO-CTAB-SiC composite was characterized by X-ray diffraction, field-emission scanning electron microscopy, Fourier transformed infrared spectra, inductively coupled plasma-atomic emission spectrometry and fluorescence emission (PL). Its photocatalytic activity was evaluated by the degradation of rhodamine B in the microwave discharge electrodeless lamp (MDEL) system. The experimental results showed that TiO-CTAB-SiC composite exhibited obviously higher photocatalytic activity in the MDEL system compared with pure TiO nanopowders. Their reusability and separation performance were evaluated by recycling experiments. The reasons for the improvement in photocatalytic performance were discussed in detail. [ABSTRACT FROM AUTHOR]

In participation of the fifth statistical assessment of modeling of proteins and ligands (SAMPL5), the strength of association of six guests ( 3- 8) to two hosts ( 1 and 2) were measured by H NMR and ITC. Each host possessed a unique and well-defined binding pocket, whilst the wide array of amphiphilic guests possessed binding moieties that included: a terminal alkyne, nitro-arene, alkyl halide and cyano-arene groups. Solubilizing head groups for the guests included both positively charged trimethylammonium and negatively charged carboxylate functionality. Measured association constants ( K ) covered five orders of magnitude, ranging from 56 M for guest 6 binding with host 2 up to 7.43 × 10 M for guest 6 binding to host 1. [ABSTRACT FROM AUTHOR]

Recently DNA with hexadecyltrimethyl ammonium chloride (CTMA) complex has been included in some organic electronic devices. Thermal stability is one of key parameters required for successful applications in different electronic and optoelectronic devices. This work shows a possibility of enhancing thermal stability in this complexes and analyzes origin of this enhancement. Different techniques were applied to explore this issue of solid DNA-CTMA. Results of TGA analysis, DSC calorimetry, FTIR spectroscopy, and analysis of evolved gaseous products convince that chemical composition of DNA-CTMA complex remains fixed at temperatures <200-220 °C. In contrast, broadband dielectric spectroscopy applied to freshly prepared thin films of DNA-CTMA revealed at 150-160 °C a permanent and irreversible change of dielectric properties. This phenomenon may be attributed to a transformation affecting the microstructure. Some experiments were conducted also for the native DNA as a reference. We demonstrate that DNA-CTMA complex chemical composition is more stable at temperatures about 200 °C with respect to DNA which is very important for laser operated optoelectronic applications. [ABSTRACT FROM AUTHOR]

We investigated the influence of the quaternary ammonium salt (QAS) called IM ( N-(dodecyloxycarboxymethyl)- N, N, N-trimethyl ammonium chloride) on yeast cells of the parental strain and the IM-resistant mutant (EO25 IM) growth. The phenotype of this mutant was pleiotropic. The IM mutant exhibited resistance to ethanol, osmotic shock and oxidative stress, as well as increased sensitivity to UV. Moreover, it was noted that mutant EO25 appears to have an increased resistance to clotrimazole, ketoconazole, fluconazole, nystatin and cycloheximide. It also tolerated growth in the presence of crystal violet, DTT and metals (selenium, tin, arsenic). It was shown that the presence of IM decreased ergosterol level in mutant plasma membrane and increased its unsaturation. These results indicate changes in the cell lipid composition. Western blot analysis showed the induction of Pma1 level by IM. RT-PCR revealed an increased PMA1 expression after IM treatment. [ABSTRACT FROM AUTHOR]

In the present study, we reported a convenient route to prepare well dispersed and functionalized K-doped core-shell upconversion nanoparticles (UCP) by layer-by-layer (LbL) assembly of polyelectrolytes. UCP was firstly transferred to aqueous phase using cationic surfactant cetyl trimethyl ammonium bromide (CTAB) via hydrophobic interaction without removing the existing oleic acid (OA). Then the positively charged hydrophilic UCP@CTAB was further alternately deposited with negatively charged [poly (sodium 4-styrenesulfonate)] (PSS), positively charged [poly (allylamine hydrochloride)] (PAH) and negatively charged [poly (acrylic acid)] (PAA). The final carboxyl functionalized UCP@CTAB@PSS@PAH@PAA was then conjugated with monoclonal antibody1 (AB1) of procalcitonin (PCT), resulting in successful detection of PCT antigens based on the immunochromatographic assay (ICA). Linear response was achieved from 0 to 10 ng/mL, and the lowest limit of detection (LLD) was 0.18 ng/mL. [ABSTRACT FROM AUTHOR]

We investigate the effect of cetyl-trimethyl-ammonium-bromides (CTAB) concentration on the fluorescence of Rhodamine-6G in water. This spectroscopic study of Rhodamine-6G in presence of CTAB was performed using two-photon-induced-fluorescence at 780 nm wavelength using high repetition rate femtosecond laser pulses. We report an increment of ∼10 % in the fluorescence in accordance with ∼12 % enhancement in the absorption intensity of the dye molecule around the critical micellar concentration. We discuss the possible mechanism for the enhancement in the two-photon fluorescence intensity and the importance of critical micellar concentration. [ABSTRACT FROM AUTHOR]

The ion-exchange properties of interpenetrating polymer networks (IPNs) have been studied to provide metal-ion transport with high selectivity. Polypropylene (PP) membranes incorporating poly[(ar-vinylbenzyl) trimethylammonium chloride], P(ClVBTA), poly[2-(acryloyloxy)ethyl]trimethylammonium chloride] P(ClAETA), poly(acrylic acid) P(AA), poly(2-acrylamidoglycolic acid) P(AGA), poly(glycidylmethacrylate- N-methyl- d-glucamine) P(GMA-NMG), poly(2-acrylamido-2-methyl-1-propane sulfonic acid) P(AMPS), and poly[sodium (styrene sulfonate)], P(SSNa) were modified via an 'in situ' radical-polymerization. The surface of PP was activated by a hydrophilic grafted polyelectrolyte and then pressure injection was used for impregnation of the reactive solution in the membrane. The following conditions were varied: the functional monomer, grafted polyelectrolyte, and cross-linked concentration. The modified PP membranes were characterized using SEM/EDS, FT-IR, electrokinetic potential, and Donnan dialysis for the chromium ion transport. The modified membranes exhibited hydrophilic character with a water-uptake capacity between 15 and 40 % and a percentage of modification between 2.5 and 5.5 % in comparison with the behavior of the unmodified polypropylene membrane as the blank probe. Hexavalent chromium ions were efficiently transported by the modified membranes containing P(ClVBTA) (61.2 %) and only 5.8 % of trivalent chromium were extracted at pH 3.0 using a 1 mol/L NaCl solution as the extraction reagent. Similarly, Cr(III) transport using membranes modified with P(SSNa) achieved 42.1 % extraction at pH 3.0 using 1 mol/L NaCl as the extraction reagent and 2.5 % extraction was achieved for Cr(VI). Unmodified PP membrane shows Cr(VI) extraction percentage between 1.6 and 3.1 %, and Cr(III)extraction percentage between 2.3 and 2.6 %. [ABSTRACT FROM AUTHOR]

The nanocomposites of TiO-CeO are synthesized by a simple and cost-effective sol-gel method with cetyl trimethyl ammonium bromide (cationic surfactant) as capping agent at 500 °C. The X-ray diffraction analysis revealed phase purity of synthesized product. The X-ray photoelectron spectroscopy showed Ti oxidation state of Ti element while Ce element was exist as a mixture of Ce and Ce oxidation state. The UV-Vis diffuse reflectance spectra clearly indicate the positive alteration in the optical response of TiO nanoparticles by the introduction of CeO nanoparticles. Scanning electron microscopic study revealed the formation of nanoclusters of spherical particles with uniform size distribution. Energy dispersive X-ray analysis confirmed the elemental composition. Fourier transform infrared spectroscopy analysis confirmed the presence of Ti-O-Ti stretching modes in the range of 900-400 cm. Photoluminescence spectroscopy was used to study the rate of recombination and transfer behaviors of photoexcited electron-hole pairs in the nanocomposites. Further, the photocatalytic activity of pure TiO nanoparticles and nanocomposite of TiO was studied using methyl orange. The TiO:CeO nanocomposites exhibit high dye degradation compare with pure TiO nanoparticles. The composite TiO:CeO (7:3) shows highest photocatalytic degradation of methyl orange dye in UV (60 min) and sunlight (90 min). [ABSTRACT FROM AUTHOR]

We have investigated catanionic mixtures of the anionic surfactant sodium oleate with various alkyltrimethyl ammonium bromides of different alkyl chain length between octyl and tetradecyl. Around equimolar mixing vesicles are formed but only for a chain length of decyl and longer. For shorter chains and with increasing asymmetry of the mixing ratio, the vesicle phase disappears and instead wormlike micelles are formed, which leads to a viscoelastic behaviour of the samples. The vesicle systems are often also viscoelastic, if they contain densely packed multi-lamellar vesicles but this depends also on their salt content, as for instance the salt-free decyl system forms unilamellar vesicles of low viscosity. It is observed that the most well-defined vesicles (unilamellar) occur upon admixing the intermediate cationic surfactant with the dodecyl chain, which then results in low viscous solutions. In general, by appropriately choosing the mixing ratio, the length of the alkyl chain and also the ionic strength of the solution can tune the structure and the properties of these catanionic surfactant mixtures over a wide range in a systematic fashion. [ABSTRACT FROM AUTHOR]

Cationization of cotton fabrics was performed utilizing 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC) in a cold pad batch procedure. Cotton fabrics were cationized at three levels 2.11, 4.23, and 8.45 % on weight of fabric of CHPTAC. Different neutralization schemes were employed on each cationization level to determine the effect of pH and process parameters on minimizing the amount of free trimethyl amine (TMA) in cationized cotton. Employing a solvent extraction method and gas chromatography/flame ionization detection (GC/FID), TMA was extracted and determined in parts per million (ppm) from the neutralized and sealed and aged cationized fabric. The results show that it is straightforward to quantify the concentration of TMA in cationized fabric and that the lowest levels of TMA in cationized cotton are achieved with by an initial warm rinse to remove excess sodium hydroxide, followed by acidification bath to achieve an acidic pH, and ending with a subsequent cold final rinse. [ABSTRACT FROM AUTHOR]

The poisoning effect of ammonia, trimethyl ammonium (TMA), and triethyl ammonium (TEA) on an Au/C catalyst in glycerol electrooxidation was investigated by using cyclic voltammetry, chronoamperometry (CA), and chronopotentiometry (CP) techniques. These ternary ammoniums are the possible degradation products of quaternary ammonium functional groups that are mainly contained in anion exchange membranes (AEMs) used in fuel cells. The most poisonous species was NH, followed by TEA and TMA, which is consistent with their p K trends. Via a cyclic voltammogram, poisoning effects were observed from the shift of the potentials at maximum current density, the recovery of oxidation currents in negative scans, and the drops in current density as compared to the ammonium-free electrolyte. The maximum current density decreased about 44 % in the presence of 1 mM NH, but it showed only small effects for TMA and TEA at this concentration. The poisoning effects of TMA and TEA were more pronounced at a concentration of 10 mM. TEA displayed harsh effects in the CA and CP results. The cause of the current drop was the strong adsorption of these species in the same potential region of glycerol electrooxidation. Finally, the results suggested the use of methyl-substituted amines as a functional group in an AEM when Au was used as the electrocatalyst. [ABSTRACT FROM AUTHOR]

In this current work, a series of cellulose-based flocculants, carboxymethyl cellulose- graft-poly[(2-methacryloyloxyethyl) trimethyl ammonium chloride] (CMC- g-PDMC) with different grafting ratios were successfully synthesized. CMC- g-PDMC bears high flocculation performance in removal of an anionic dye, Acid Green 25 (AG25), at various pH conditions, which is due to improvement of both positive charge and molecular weight after modification. Moreover, the dye removal efficiency is mostly improved with the increase of grafting ratio. Among the four tested salt additives, CMC- g-PDMC exhibits good salt resistance except for sodium chloride in the measured salt concentration range. Furthermore, the image analysis in combination with fractal theory has been employed to investigate the flocs properties including floc size and fractal structure for studying the flocculation mechanism in detail. It is confirmed that charge neutralization and bridging flocculation effects both play important roles in removal of AG25 from water. [ABSTRACT FROM AUTHOR]

Cationisation during the mercerisation process with an epihalohydrin results in novel cotton cellulose that gives a new dimension to cotton pre-treatment and finishing. The modified cotton retains all the beneficial properties of mercerised cotton with a change of the surface charge that ensures further quality improvement. The present paper deals with systematic investigations of the interface phenomena of cationised cotton fabric with an epihalohydrin; 2,3-epoxypropyl trimethyl ammonium chloride during and after mercerisation process. The water, ionic surfactant and dyestuff adsorption, as well as surface free energy, electrokinetic potential, isoelectric point and point of zero charge determined according to the streaming current/streaming potential method; and specific amount of surface charge of modified cotton fabrics are researched. [ABSTRACT FROM AUTHOR]

Stimuli responsive hydrogels have shown enormous potential as a carrier for targeted drug delivery. In this study we have developed novel pH responsive hydrogels for the delivery of 5-fluorouracil (5-FU) in order to alleviate its antitumor activity while reducing its toxicity. We used 2-(methacryloyloxyethyl) trimetylammonium chloride a positively charged monomer and methacrylic acid for fabricating the pH responsive hydrogels. The released 5-FU from all except hydrogel (GEL-5) remained biologically active against human colon cancer cell lines [HT29 (IC = 110-190 μg ml) and HCT116 (IC = 210-390 μg ml)] but not human skin fibroblast cells [BJ (CRL2522); IC ≥ 1000 μg ml]. This implies that the copolymer hydrogels (1-4) were able to release 5-FU effectively to colon cancer cells but not normal human skin fibroblast cells. This is probably due to the shorter doubling time that results in reduced pH in colon cancer cells when compared to fibroblast cells. These pH sensitive hydrogels showed well defined cell apoptosis in HCT116 cells through series of events such as chromatin condensation, membrane blebbing, and formation of apoptotic bodies. No cell killing was observed in the case of blank hydrogels. The results showed the potential of these stimuli responsive polymer hydrogels as a carrier for colon cancer delivery. [ABSTRACT FROM AUTHOR]

Polyaniline-FeO nanocomposite with and without ionic liquid were successfully synthesized via in situ polymerization using cetyl trimethylammonium bromide (CTAB) as surfactant. Both TG analysis and FT-IR measurements proved the presence of organic layer on the surface of FeO nanoparticles. The influence of 1-butyl-3-methyl-imidazolium bromide (BMIMBr) as ionic liquid on the structure, conductivity, and magnetic property of PANI-FeO-CTAB nanocomposite were studied in detail. The results show that imidazolium-based ionic liquids BMIMBr acts as an anchor agent during the formation of PANI-FeO-CTAB nanocomposite. Ionic liquid significantly deteriorated nanocomposite's magnetic properties, and contributed to non-saturated M-H curve due to the disappearance of antiferromagnetic interactions. It has also an improving effect on AC and DC conductivities. The most important effect of IL is observed in real part of permittivity of PANI-FeO-CTAB that it has negative high values at low frequency low temperature region. Due to the negative dielectric constant, material exhibits uncommon properties in electromagnetic waves scattering and attraction between similar charges. This possibility provokes research on these composites as high T superconductors, negative index materials and microwave absorbers. [ABSTRACT FROM AUTHOR]

Grain moisture in maize at harvest depends on the grain drying rate (GDR) after physiological maturity. The maize plants with high GDR can reduce grain moisture rapidly, which will shorten the drying time after harvest and prevent the grain to be mildew and enhance maize quality. In this study, A total of 280 recombinant inbred lines that were derived from a cross between Ji846 (high drying rate, 1.18 % day) and Ye3189 (slow drying rate, 0.39 % day) were used to construct genetic linkage map and identify QTL underlying GDR in different environments. A genetic linkage map was constructed containing 97 SSR and 49 AFLP markers, which covered 2356.8 cM of the maize genome, with an average distance of 16.1 cM. Composite interval mapping identified 14 QTL for GDR after physiological maturity located on chromosomes 2, 3, 5, 6 and 8. The additive effects of QTL were all from Ji846. The range of phenotypic variation explained by the QTL was 5.05-16.28 %. But only two QTL (qKdr-2-1, qKdr-3-6) were identified across both locations. qKdr-2-1 positioned between the markers phi090-umc1560 on chromosome 2 explained 15.59 % of the phenotypic variance, and the other qKdr-3-6 positioned between the markers phi046-bnlg1754 on chromosome 3 explained 10.28 % of the phenotypic variance. [ABSTRACT FROM AUTHOR]

This study investigated the effects of organic polymers (polyethylene glycol and hexadecyltrimethylammonium) on structures of calcium silicate hydrates (C-S-H) which is the major product of Portland cement hydration. Increased surface areas and expansion of layers were observed for all organic polymer modified C-S-H. The results from attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopic measurements also suggest lowered water contents in the layered structures for the C-S-H samples that are modified by organic polymers. Scanning transmission X-ray microscopy (STXM) results further supports this observation. We also observed difference in the extent of C-S-H carbonation due to the presence of organic polymers. No calcite formed in the presence of HDTMA whereas formation of calcite was observed with C-S-H sample modified with PEG. We suggest that the difference in the carbonation reaction is possibly due to the ease of penetration and diffusion of the CO. This observation suggests that CO reaction strongly depends on the presence of organic polymers and the types of organic polymers incorporated within the C-S-H structure. This is the first comprehensive study using STXM to quantitatively characterize the level of heterogeneity in cementitious materials at high spatial and spectral resolutions. The results from BET, XRD, ATR-FTIR, and STXM measurements are consistent and suggest that C-S-H layer structures are significantly modified due to the presence of organic polymers, and that the chemical composition and structural differences among the organic polymers determine the extent of the changes in the C-S-H nanostructures as well as the extent of carbonation reaction. [ABSTRACT FROM AUTHOR]

Using two cationic methacrylate polymers: poly([2-(methacryloyloxy)ethyl] trimethyl ammonium iodide) (PDMQ) and poly[(stearyl methacrylate)- stat-([2-(methacryloyloxy)ethyl] trimethyl ammonium iodide)] (PSMA13Q), we modified microfibrillated cellulose (MFC) water suspensions. The aim was to affect the flocculation and rheological behavior of the MFC suspension. PDMQ is a strongly cationic polymer while PSMA13Q, also a cationic polymer, contains hydrophobic segments. We studied the MFC/polymer suspension rheological properties with a rotational rheometer in oscillatory and flow measurements. To observe structural changes in suspensions at different shear rates, we measured flow curves with transparent outer geometry and photographed the sample with a digital camera. The oscillatory measurements showed that a small amount of the cationic PDMQ in the MFC suspension strengthened the gel, whereas a small amount of amphiphilic PSMA13Q weakened it. Increased amounts of either polymer increased the gel strength. PSMA13Q also changed the rheological character of the MFC suspension turning it more fluid-like. When we photographed the flow curve measurement, we saw a clear change in the floc structure. This floc structure rupture coincided with a transient region in the flow curve. [ABSTRACT FROM AUTHOR]

The middle-phase behavior for the systems of cetyltrimethylammonium bromide (CTAB)/poly-ethyleneglycol-9-monododecyl ether (AEO)/alcohol/oil/brine and CTAB/octylphenolpolyoxyethylene-10-ether (Triton X-100)/alcohol/oil/brine have been studied with ɛ-β fishlike phase diagram method. The interfacial layer composition was determined, and some significant physicochemical parameters are derived from the hydrophilic-lipophilic balance plane equation. The effects of different alcohols, oils, temperature and inorganic salt (NaCl) on the middle-phase behavior of microemulsion formed by composite CTAB/AEO systems were also investigated systematically. The effects of different factors on the phase behavior of microemulsions formed by CTAB/AEO and CTAB/TX-100 systems were compared. The results suggest that the solubilization of CTAB/AEO microemulsion is higher than that of CTAB/TX-100 system under the same conditions. [ABSTRACT FROM AUTHOR]

Scanning probe microscopy is used to study adsorption films of sodium polystyrenesulfonate/dodecyltrimethylammonium bromide complexes, which are transferred from aqueous solution surfaces to the mica surface by the Langmuir-Blodgett method. It is established that the results obtained at surfactant concentrations below critical micelle concentration agree with the conclusions on the structure of the films dased on the data of the dilatational surface rheology (Noskov, B.A., Loglio, G., Miller, R., J. Phys. Chem. B, 2004, vol. 108, p. 18615). At low concentrations of the low-molecular-mass surfactant, a thin adsorption film containing a large number of holes is formed on the surface of an aqueous solution. As the surfactant concentration is increased to reach the region of a dramatic reduction in the dynamic surface elasticity, the morphology of the film drastically changes; i.e., dense three-dimensional aggregates are formed on the solution surface. [ABSTRACT FROM AUTHOR]

We have studied the possibility of using new anion exchangers based on silica with covalently-immobilized trimethyl ammonium propyl and dimethyloctadecyl ammonium propyl groups for sorption concentration of trace amounts of iodine iodide ions followed by their spectrophotometric determination. Sorption properties of new anion exchangers were compared with the properties of the industrial anion exchangers AV-17. [ABSTRACT FROM AUTHOR]

1,3,5-Trimethyl-1,3,5-tris(hexafluoroalkyl)cyclotrisiloxanes were synthesized by hydrolytic polycondensation of methyl(hexafluoroalkyl)dichlorosilanes, and 1,1,3,3,5-pentamethyl-5-(trifluoromethyltrifluorobicyclo[2.2.1]heptyl)cyclotrisiloxane was synthesized by heterofunctional condensation. The effect of hexafluoroalkyl substituents at the silicon atom on the reactivity of the siloxane bonds has been studied. [ABSTRACT FROM AUTHOR]

Amphiphilic poly(oxyethylene)-b-poly(oxybutylene) block copolymers having hydrophilic block end-capped with neutral dimethylamino (DE79B34) and cationic trimethyl ammonium (TE79B34) groups, respectively were investigated for their interactions with ionic surfactants, sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) using tensiometry, conductometry and dynamic light scattering. The self-assembly of DE79B34 and TE79B34 occur at 0.7 g/dm3 and 0.8 g/dm3, respectively. TE79B34 binds favorably with oppositely charged SDS, causing a substantial change in surface tension compared to other surfactant-polymer systems. In mixed polymer-surfactant systems, the micellization was promoted in the presence of SDS, but it was suppressed with CTAB. Such behavior is expected for cationic block copolymers, since they can engage into ion-pair formation with anionic SDS. For neutral polymers, the behavior is reflective of surfactants’ head group hydrophobicity. The head groups of CTAB are more hydrophobic and their existence in the proximity of hydrophobic segments of polymers induces shape transition to non-spherical morphologies. Gibb’s free energy of adsorption at air - water interface is negative for SDS, CTAB and surfactant-block copolymer systems, indicating that the process is highly spontaneous. The increase in entropy of TE79B34 during micelle formation with temperature is due to disturbance of hydrophobic structure of water molecules, thus hydrophobic parts are removed from bulk solution to the interface and also in the interior of micelle the freedom of hydrophobic part is increased. The dynamic laser light scattering results revealed that due to presence of block copolymers pre-micellar aggregates were favored. [ABSTRACT FROM AUTHOR]