bluuebunny/crossref_metadata_2025_split huggingface dataset:
Primary Afferent NMDA Receptors Increase Dorsal Horn Excitation and Mediate Opiate Tolerance in Neonatal Rats
Authors: Zeng Jinsong , Thomson Lisa M. , Aicher Sue A. , Terman Gregory W. 
Published: November 2006

Repeated exposure to opiates produces analgesic tolerance, which limits their clinical usefulness. Whole-cell voltage-clamped lamina I cells in spinal slices from opiate-tolerant neonatal rats show an increase in miniature, spontaneous, and primary afferent-evoked EPSCs when compared with lamina I cells from opiate-naive rat spinal slices. This increased excitation can be blocked by the NMDA receptor (NMDAR) antagonist APV, apparently acting at NMDARs on primary afferents. Consistent with these results, electron microscopy demonstrates an increased incidence of NMDARs in substance P-containing spinal dorsal horn primary afferent terminals in opiate-tolerant rats. Moreover, superfusion of spinal slices from opiate-tolerant rats with NMDA produces a reversible increase in miniature EPSC (mEPSC) frequency in contrast to a decrease in mEPSC frequency produced by NMDA in opiate-naive slices. Finally, NMDAR antagonists inhibit the expression of opiate tolerance both in inhibiting EPSCs in spinal slices and in inhibiting behavioral nociceptive responses to heat.NMDAR antagonists have been reported in many studies to inhibit morphine analgesic tolerance. Our studies suggest that an increase in primary afferent NMDAR expression and activity mediates a hypersensitivity to noxious stimuli and causes the inhibition of opiate efficacy, which defines tolerance.
Interactions between ants and aphidophagous and coccidophagous ladybirds
Authors: Majerus Michael E. N. , Sloggett John J. , Godeau Jean‐François , Hemptinne Jean‐Louis 
Published: November 2006

AbstractAphidophagous and coccidophagous coccinellids come into conflict with homopteran‐tending ants for access to food. Antagonistic interactions between coccinellids and ants may be competitive or non‐competitive. Competitive interactions occur when coccinellids attack aphids or coccids that are being tended by ants for honeydew. Non‐competitive interactions include all interactions away from ant‐tended homopteran colonies. We here review observations and studies of such interactions. We note that most competitive interactions occur at times when untended aphids/coccids are scarce. We describe the chemical and physical defences that coccinellids use against ant aggression and consider whether these have evolved as general anti‐predator deterrents or specifically in response to ants. Myrmecophilous coccinellids are then considered, with particular focus on the two most studied species, Coccinella magnifica and Platynaspis luteorubra. We note that the myrmecophily of the two species has the same adaptive rationale—to enable the ladybirds to prey on ant‐tended aphids at times of aphid scarcity—but that it is based on different traits to facilitate life with ants. Finally, we consider the role of ants in the evolution of habitat specialisation in some coccinellids.
O‐etherification between glycerol and glycerol monooleate—demonstration of formation of diglycerol monooleate and triglycerol monooleate by fast atom bombardment‐mass spectroscopy and 13C nuclear magnetic resonance
Authors: Eychenne Valérie , Debrauwer Laurent , Mouloungui Zéphirin 
Published: November 2006

AbstractTo prepare glycerol monooleate, we reacted glycerol with oleic acid in the presence of a K1411 sulfonic acid resin in the H+ form. We utilized glycerol monooleate as an emulsifying agent, as it is a nonionic surfactant that is compatible with the initially biphasic reaction medium. If the expected product does not form, small amounts of a highly polar compound are produced. Both diglycerol monooleate and triglycerol monooleate were isolated by preparative chromatography on a silica column (hexane/chloroform/acetone, 25∶50∶50), and were formally identified by fast atom bombardment (FAB)‐mass spectroscopy in positive mode. The products were polyglycerol monoesters. The nature of the products was confirmed by the use of different FAB matrices with or without cationization by alkali metals. The structure of the product was then confirmed by 13C nuclear magnetic resonance. we can now propose a new method of polyglycerol ester preparation that yields interesting nonionic emulsifying agents.
Alcohol‐free diphenyl oxide disulfonate middle‐phase microemulsion systems
Authors: Wu Bin , Harwell Jeffrey H. , Sabatini David A. , Bailey Jason D. 
Published: November 2006

AbstractDiphenyl oxide disulfonate (DPDS) surfactants were successfully used to formulate Winsor Type III middlephase microemulsion systems with tetrachloroethylene (PCE) and decane. To our knowledge this is the first time that monochain DPDS surfactant phenyloxide monohexadecyl disulfonate surfactant (C16MADS) and commercially available DOWFAX 8390 were found to form middle‐phase microemulsion systems with oils. Hydrophobic dioctyl sodium sulfosuccinate (Aerosol OT) was also used as a cosurfactant to lower the systems' hydropholic‐liphophilic balance. Two organic acids (hydrophobic octanoic acid and hydrophilic l‐tartaric acid) were used in place of the alcohol to formulate middle‐phase microemulsion. The middle‐phase microemulsion systems dramatically increased organic solubility when compared to micellar DPDS surfactant systems. Winsor Type I systems near the Type I–III boundary produced “super” solubilization for hydrophobic oils. Findings from this study enable us to improve DPDS solubilization enhancement of hydrophobic compounds.
Synthesis, characterization and surface properties of 1‐N‐l‐tryptophan‐glycerol‐ether surfactants
Authors: Pegiadou S. , Perez L. , Infante M. R. 
Published: November 2006

AbstractA novel homologous series of 1‐N‐l‐tryptophanglycerol‐ether surfactants was synthesized and characterized. The precursor compounds, 3‐alkyloxy‐1‐chloropropan‐2‐ols, were prepared from epichlorohydrin and aliphatic alcohols with alkyl chain lengths of 9–16 carbon atoms. Tryptophan was then attached to the monosubstituted glycerol backbone from its α‐amino group through an α‐NH‐C bond. Structural assignment of the new compounds was made on the basis of elemental analysis and spectroscopic data. Critical micelle concentrations of the new surfactants, as well as the negative logs of the surfactant concentrations required to reduce the surface tension of the solvent by 20 mN/m (pC20) and the interfacial areas occupied by the surfactant molecules, were calculated from aqueous surface tension measurements using the Wilhelmy plate technique.
Analysis of surfactants: Part I
Authors: Morelli John J. , Szajer Gerald 
Published: November 2006

AbstractWe present a comprehensive review of the literature devoted to the analysis of surfactants. The period covered is 1995 through 1998. We address patents, reviews, books, journal articles, and any conference proceedings abstracted by Chemical Abstract Services. We consider classical, instrumental, and state‐of‐the‐art analytical applications, including those not in common practice but in a developmental stage. We also include analytical techniques that make use of surfactants for improved performance, although such treatment is not comprehensive. Literature from foreign language sources is covered as completely as practical.
Surfactant‐polymer interactions: Mixed micelles of hexadecylpyridinium bromide and trimethyltetradecylammonium bromide in aqueous poly(vinylpyrrolidone) solution
Authors: Bakshi Mandeep Singh 
Published: November 2006

AbstractThe conductance of hexadecylpyridinium bromide (HPyBr) and trimethyltetradecylammonium bromide (TTAB) mixtures over the entire mole fraction range of HPyBr (αHPyBr) was measured in aqueous poly(vinylpyrrolidone) (PVP) solution containing 1, 5, and 10 wt% PVP at 30°C. Each conductivity curve showed two breaks corresponding to two aggregations throughout the whole mole fraction range of HPyBr and TTAB mixtures except for pure TTAB for which a single break corresponding to the conventional critical micelle concentration was observed. The two aggregation processes in the presence of low amounts of PVP were mostly similar to those in pure water, however, 10 wt% PVP shifted the break, corresponding to the second aggregation, toward the higher value. This was attributed to HPyBr/PVP interactions, which were also evident from the appearance of a second break in the conductivity (κ) plot of pure HPyBr in aqueous 10 wt% PVP. From conductivity data, various micellar parameters in the presence of PVP were determined and discussed from the standpoint of micelle‐polymer interactions. The mixing behavior of HPyBr and TTAB corresponding to the first break in the presence of PVP was ideal for the most part and identical to that in pure water.
Direct ethoxylation of a longer‐chain aliphatic ester
Authors: Hreczuch W. , Trathnigg B. , Dziwiński E. , Pyzalski K. 
Published: November 2006

Abstract2‐Ethylhexyl laurate, as an exemplary longer‐chain aliphatic ester, was subjected to direct ethoxylation. The synthesis was described and the obtained products were analyzed qualitatively by means of the mass spectrometry and chromatographic methods. Solubility of the obtained ethoxylates was studied by determination of their cloud points in selected model solutions. It was shown that longer‐chain aliphatic esters are feasible as raw materials for ethoxylation in the presence of an appropriate catalyst. They undergo effective and selective reaction with ethylene oxide without formation of excessive amounts of by‐products. The obtained products exhibit typical properties of ethoxylate‐type nonionic surfactants. Their solubility in water and butyldiglycol solution was relatively lower compared to their methyl ester equivalents.
Kinetics and thermodynamics of sulfuric acid‐mediated cleavage of substituted diaryl sulfones
Authors: Ward Robert S. , Diaper Richard L. , Roberts David W. 
Published: November 2006

AbstractThe cleavage of di‐p‐tolyl sulfone with concentrated sulfuric acid has been shown to occur at elevated temperatures (>120°C). The products were confirmed as the corresponding sulfonic acids by gas chromatography‐mass spectrometry analysis of the sulfonate ester derivatives. The cleavage reactions of a series of di‐p‐substituted diaryl sulfones with sulfuric acid have been studied. A method using a double end‐point titration has been used to quantify the amounts of sulfonic acid formed as the reactions proceed. These data have been used to construct second‐order rate plots over a range of temperatures and to determine rate constants for the cleavage reactions. The second‐order rate plots showed good linearity. Activation energies were determined from Arrhenius plots of the second‐order rate constants over a range of temperatures. The presence of electron‐donating groups decreases the activation energy of the reaction, whereas the presence of electron‐with‐drawing groups increases the activation energy of the reaction.
Synthesis and surface properties of N‐dodecyl‐N,N‐bis[3‐(aldonamido)propyl]amine‐N‐oxides
Authors: Piasecki Andrzej , Karczewski Sławomir , Syper Ludwik 
Published: November 2006

AbstractA new group of saccharide surfactants, N‐dodecyl‐N,N‐bis[3‐(aldonamido)propyl]amine‐N‐oxides (derivatives of d‐gluconic, d‐glucoheptonic, and lactobionic acids), were synthesized with high yields by one‐step oxidation reaction of an appropriate N‐dodecyl‐N,N‐bis[3‐(aldonamido)‐propyl]amine with an excess of 30 wt% of an aqueous solution of hydrogen peroxide. Their structures and purity were confirmed by means of elemental analysis, electrospray ionization mass spectrometry, and 1H and 13C nuclear magnetic resonance spectroscopy. In comparison to an appropriate N‐dodecyl‐N,N‐bis[3‐(aldonamido)propyl]amine, the investigated N‐oxides are more soluble in water with similar critical micelle concentration values and show higher surface effectiveness. They are low‐foamable but in mixtures with sodium dodecyl sulfate form high‐volume and stable foams in a wide range of mixture compositions.
Adsorption properties of amphiphilic polyoxyalkylenated dimethylpolysiloxane derivatives on keratin
Authors: Asakura Kouichi , Iida Ayuko , Kitagata Ryoichi , Yoshida Atsushi , Osanai Shuichi , Kuroda Akihiro 
Published: November 2006

AbstractAdsorption properties of two types of dimethylpolysiloxane backbone derivatives, perfluoroalkyl polyoxyethylenated dimethylpolysiloxane (FPD) and polyoxyethylenated dimethylpolysiloxane (PD), onto keratin surfaces were investigated. Both polymers are amphiphilic, since they possess hydrophilic polyoxyethylene groups. FPD contains a perfluoroalkyl group that provides both water‐and oil‐repellent properties, whereas PD lacks these groups. Adsorption properties of these polymers onto keratin surfaces are considered a good index to evaluate these compounds as nonionics used in hair‐coating agents, since keratin is a major component of hair. FPD was more likely to be adsorbed and less likely to be eliminated from the keratin surface than PD. Once FPD had been adsorbed onto the keratin surface, it was very slowly washed from the surface when it was immersed in stationary water, whereas PD polymers were quickly washed from the keratin surface. Even in running water, rapid elimination of FPD was not observed. The strong resistance to loss of FPD after washing with a large quantity of water may be due to the water‐repellent nature of the perfluoroalkyl groups. As a comparison, FPD adsorption onto a glass surface was also investigated. The affinity to the glass surface was found to be less than to the keratin surface.
31P nuclear magnetic resonance studies on alkyl phosphate emulsifiers in cosmetic oil‐in‐water emulsions
Authors: Plass J. , Emeis D. , Blümich B. 
Published: November 2006

AbstractCosmetic oil‐in‐water emulsions with a stearyl phosphate emulsifier are examined by means of static and dynamic 31P nuclear magnetic resonance (NMR) techniques to characterize the molecular properties of the emulsifier in situ. The interfacially bound emulsifier can be deteced by high‐resolution NMR spectroscopy, whereas the excess emulsifier exists as a solid lipid phase not detectable by this technique. The emulsions and the emulsifier raw material, consisting of monostearyl phosphate as well as distearly phosphate, are examined by solid state cross polarization magic angle spinning NMR spectroscopy to prove the existence of solid emulsifier phases in the emulsions. By applying dynamic 31P NMR methods to the interfacially bound emulsifier, information about the molecular dynamics at the interface is obtained. The results of the T1 and T2 relaxation time measurements indicate a restricted motion of the molecules that is dependent on the oil droplet size in the emulsions. This is verified by 31P NMR pulsed gradient spin echo self‐diffusion measurements on emulsions with different droplet sizes. Only about 5 wt% of the total emulsifier used is bound at the interface; the excess forms solid lipid phases. The coverage of the interface seems to be independent of the emulsifier concentration. Only the monoester of the emulsifier raw material shows interfacial activity. Its mobility indicates the two‐dimensional environment of the molecules on the surface of the oil droplets.
The effect of shear and oil/water ratio on the required hydrophile‐lipophile balance for emulsification
Authors: Vander Kloet Jana , Schramm Laurier L. 
Published: November 2006

AbstractRequired hydrophile‐lipophile balance (HLB) values were examined in terms of the nature of kerosene‐water, both oil‐in‐water (O/W) and water‐in‐oil (W/O), emulsions formed using Span 80/Tween 80 surfactant blends. Both the nature of the emulsification method and the oil/water ratio were critical in determining the resulting emulsion type. Both high‐ and low‐shear conditions were investigated. Under high shear, low internal phase emulsions formed using the surfactant mixtures that corresponded to the required HLB values for emulsification involving kerosene (6 for W/O and 14 for O/W). However, at low shear, high internal phase (concentrated) emulsions resulted. Furthermore, depending on the oil/water ratio, some of the high internal phase emulsions were opposite to the type expected, given the HLB of the surfactant blend used. From these results, it appears that the emulsification technique (applied shear and oil/water ratio) used can be of greater importance in determining the final emulsion type than the HLB values of the surfactants themselves.
Novel general procedure for the preparation of homogeneous nonionic surfactants
Authors: Sallay Péter , Farkas László , Szlovák Zoltán , Rusznák István , Bakó Péter , Ahmed Mohamed , Tungler Antal , Fogassy Gabriella 
Published: November 2006

AbstractHomogeneous nonionic surfactants were produced by the ethoxylation of a selected unit of a homolog series. These particular products are of use for the analysis of nonionics and for the determination of surface characteristics. A new general method for the synthesis of homogeneous nonionic surfactants is described. Ethylene glycol monobenzyl ether was repeatedly reacted in Williamson synthesis (or esterified with acid chlorides in the first step), followed by hydrogenolysis with alkyl‐ or aralkyl alcohols, phenols, carboxylic acids, and amines. Homogeneous nonionics can be synthesized by this method, whereas the conventionally produced ones are usually inhomogeneous.
Displacement of poly(ethylene oxide) adsorbed on silica by a nonionic surfactant studied by spin labeling
Authors: Hommel H. , Van Damme H. 
Published: November 2006

AbstractPoly(ethylene oxide) chains labeled at one end by a nitroxide free radical were adsorbed on silica. The electron paramagnetic resonance spectrum is mainly sensitive to the local Brownian motion and shows lines typical of two different environments, namely, loops and tails protruding in solution with a fast motion, and trains adsorbed on the solid with a hindered motion. When a solution of nonionic Triton surfactant with different concentrations is put in contact with the coated surface, the polymer segments are progressively removed from the surface and the chains extend into solution. This displacement is recorded as a function of temperature and concentration and follows a well‐defined smooth path.
Disintegration of granules made from pure nonionic surfactants and surfactant mixtures
Authors: Bai Jinhua , Miller Clarence A. , Wilson John E. 
Published: November 2006

AbstractDissolution in water of pure liquid nonionic surfactants and some of their mixtures was studied in previous research in this laboratory. In the work described here, a hanging drop slide was used to study disintegration behavior in water of corresponding granules consisting of many zeolite particles bound together with a liquid nonionic surfactant. Granules disintegrated below the cloud point of the nonionic surfactant or mixture. Few differences in disintegration time were seen for various systems. However, disintegration did not occur when the neat surfactant developed viscous myelinic figures upon contact with water. Nor was it observed when a dilute aqueous phase coexisted with a surfactant‐rich L1 phase or L3 (sponge) phase at equilibrium.
Synthesis and characterization of surfactants via epoxidation of tall oil fatty acid
Authors: Hedman Björn , Piispanen Peter , Alami El‐Ouafi , Norin Torbjörn 
Published: November 2006

AbstractThe synthesis and characterization of novel surfactants derived from tall oil fatty acid methyl esters are presented. The tall oil fatty acid methyl esters, which mainly contain methyl oleate, were converted to 9,10‐epoxy derivatives and further transformed to the 9 (or 10) polyethylene glycol (PEG) ethers. Compounds with three different monomethylated PEG chain lengths with molecular weights of 350, 550, and 750, corresponding roughly to 7, 11, and 16 ethylene oxide units, were prepared. Surfactants were formed at an 89% overall yield from tall oil fatty acid. Cloud points were 46, 63, and 84°C, respectively, and surface tensions at the CMC (2.0, 1.0, and 0.4 mM, respectively) varied from 33 to 38 mN/m. Equilibrium surface tension and reflectometry measurements were made and results were similar to those of conventional long alkyl chain PEG surfactants. Results of the tensiometry and reflectometry measurements showed that the surfactants aligned better at the air‐water interface than conventional surfactants. The adsorption properties for the three surfactants were similar to those of polyoxyethylene glycol alkyl ethers.
Synthesis of long‐chain alkanesulfonates by photosulfochlorination using sulfuryl chloride
Authors: Azira Hakima , Assassi Naziha , Tazerouti Amel 
Published: November 2006

AbstractTo develop a new method for the manufacture of anionic surfactants such as alkanesulfonates, which are completely biodegradable, we used linear aliphatic hydrocarbons C12 and C14 as raw material. These hydrocarbons were transformed into the corresponding sulfochlorides in quantitative vield by photosulfochlorination with sulfuryl chloride. The operating conditions led to reaction mixtures containing all the position isomers of sulfochlorinated and chlorinated alkanes. These compounds have been identified by gas chromatography‐mass spectrometry. The isomeric distribution of different reaction products, as well as the molar ratio of the main product, the alkanesulfochlorides, vs. the by‐products, the alkanechlorides, were determined by the gas chromatogrpahy method. The particular isomeric distribution observed during these reactions was different from that of classic chain reactions, as highlighted by the values of calculated relative reactivities. After separation, purification, and alkaline hydrolysis steps, the resulting dodecane and tetradecanesulfonates showed good surface activity. Indeed, the values of the surface tensions at the critical micelle concentration (CMC) compare well with those in the literature. CMC values of these mixtures are given, and the influence of isomeric distribution on CMC values and on the surface tension values at the CMC is presented.
Contact angle of surfactant solutions on precipitated surfactant surfaces. II. Effects of surfactant structure, presence of a subsaturated surfactant, pH, and counterion/surfactant ratio
Authors: Balasuwatthi Piyada , Dechabumphen Nimit , Saiwan Chintana , Scamehorn John F. 
Published: November 2006

AbstractThe contact angle of a saturated aqueous surfactant solution on the precipitate of that surfactant was measured by using the sessile drop method. The sodium and calcium salts of alkyl sulfates (C12, C14, and C18) had advancing contact angles higher than those of alkyl trimethylammonium bromides (C14, C16, and C18). The measured advancing contact angles for several surfactant solutions did not substantially change with varying surfactant/counterion ratios; therefore, the precipitating counterion concentration (e.g., water hardness) had little effect on the wettability. The contact angles of fatty acid (C12 and C16) solutions did not show any dependence on pH between a pH of 4 and 10. The contact angles of saturated calcium dodecanoate (CaC12) solutions containing a second subsaturated surfactant (sodium dodecyl sulfate: NaDS) decreased with increasing NaDS concentrations until reaching the critical micelle concentration of the surfactant mixture. These results show that the second suractant can act as a wetting agent in this saturated surfactant system. Application of Young's equation to contact angles showed that the solid/liquid surface tension can change substantially with surfactant concentration and be important in addition to the liquid/vapor surface tension in reducing contact angles. Application of the Zisman equation results in a “critical” surface tension for the CaC12 or soap scum of 25.5 mN/m, which is comparable to difluoroethene.