bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and characterization of maltose fatty acid monoesters as biosurfactants
Authors: Allen Douglas K. , Tao Bernard Y. 
Published: November 2006

AbstractMaltose long‐chain fatty acid esters (MFAE), esterified at the 6 and 6′ position, were synthesized with stearic, palmitic, myristic, and oleic groups. Synthesis yields were 15–20% based on initial maltose present, and structural confirmation was obtained using plasma desorption mass spectrometry and nuclear magnetic resonance spectroscopy. These surfactants have surface tensions in the range of 34–36 dyn/cm at their critical micelle concentrations (CMC) of approximately 10−5–10−6 mol/L. The increased chain lengths have a marked effect, reducing CMC values for MFAE by approximately three orders of magnitude over similar carbohydrate‐based dodecyl chain sources. Within chain lengths between 14 and 18 carbons, the rate of change in CMC is significant and decreases with increasing chain length for MFAE. The melting points of MFAE are approximately 40°C, and the heat capacities range from 1.6 to 1.9 J/g·K. These numbers are comparable to those of sucrose esters, indicating their applicability in similar uses. However, because MFAE, unlike sucrose, possess an anomeric carbohydrate carbon position, these surfactants maintain their reducing nature and are susceptible to further derivatization. They are also synthesized from renewable, economical carbohydrates and lipids and may provide an excellent alternative to pertrochemical‐derived products.
Phase behavior and structural properties for the triton X‐100/n‐CnH2n+1COOH/H2O system
Authors: Shen Ming , Guo Rong 
Published: November 2006

AbstractIn the Triton X‐100/n‐CnH2n+1COOH/H2O system,n‐CnH2n+1COOH can be used as a cosurfactant. As its chain length increases, the regions of the microemulsions showing oil‐in‐water (O/W), water‐in‐oil (W/O), and bicontinuous structures decrease and at the same time, the region of the lamellar liquid crystal increases. In the O/W region, the distribution coefficientKofn‐CnH2n+1COOH between Triton X‐100 micellar phase and water phase increases with the chain length of saturated unbranched monocarboxylic acid. The relationship between the standard solubilization Gibbs free energy of saturated unbranched monocarboxylic acid and the number of methylene groups in the saturated unbranched monocarboxylic acid is given by the equation: ΔGm0=−2.364−2.818n(CH2) kJ·mol−1in the Triton X‐100 micellar system. In the lamellar liquid crystal region, small‐angle X‐ray diffraction shows that the thickness of the bilayerd0is independent of the weight ratio ofn‐CnH2n+1COOH to Triton X‐100, but the volume of the solvent penetrating from the solvent layer to the amphiphilic bilayer increases with the weight ratio ofn‐CnH2n+1COOH to Triton X‐100. Furthermore, thed0value increases with the chain length of saturated unbranched monocarboxylic acid, which will contribute to the formation and stabilization of the lamellar liquid crystal.
Linker‐modified microemulsions for a variety of oils and surfactants
Authors: Acosta Edgar , Mai Phuong Do , Harwell Jeffrey H. , Sabatini David A. 
Published: November 2006

AbstractPreviously, we reported on the use of hydrophilic and lipophilic linker molecules to enhance the solubilization capacity of chlorinated hydrocarbons using sodium dihexyl sulfosuccinate (SDHS). In this work we extend the use of linker molecules to a wider range of oils and surfactants. The data show that the linker effect works for all the systems studied and that linker‐based systems are even more economical than surfactant‐only systems for more hydrophobic oils. Using a more hydrophobic surfactant, such as sodium bis(2‐ethyl)dihexyl sulfosuccinate (Aerosol‐OT), requires a formulation enriched with a hydrophilic linker, whereas the formulation for the more hydrophilic SDHS requires the use of a more lipophilic linker. By considering the properties and appearance of the formulation before contacting with the oil, and by evaluation the coalescence dynamics, we found that hydrophilic linker‐rich formulations were preferred. These formulations were tested as fabric pretreatments for removing motor oil and hexadecane from cotton, and as flushing solutions for glass bead columns contaminated with these oils. The cleaning performance of these linker‐based systems was superior to common surfactant and pretreatment formulations in the detergency tests, achieving more than 80% removal of motor oil and hexadecane trapped in the packed‐column flushing tests.
Mixtures of anionic and cationic surfactants with single and twin head groups: Adsorption and precipitation studies
Authors: Fuangswasdi A. , Charoensaeng A. , Sabatini D. A. , Scamehorn J. F. , Acosta E. J. , Osathaphan K. , Khaodhiar S. 
Published: November 2006

AbstractThis research reports on the adsorption and precipitation of mixtures of anionic and cationic surfactants having single and twin head groups. The surfactant mixtures investigated were: (i) a single‐head anionic surfactant, sodium dodecyl sulfate (SDS), in a mixture with the twin‐head cationic surfactant pentamethyl‐octadecyl‐1,3‐propane diammonium dichloride (PODD)—adsorption was studied on negatively charged silica; and (ii) a twin‐head anionic surfactant, sodium hexadecyl‐diphenyloxide disulfonate (SHDPDS), and the single‐head cationic surfactant dodecylpyridinium chloride (DPCI)—adsorption was studied on positively charged alumina. Whereas the mixed surfactant system of SHDPDS/DPCI showed adsorption on alumina that was comparable to the of SHDPDS alone, the mixed surfactant system of SDS/PODD showed increased adsorption on silica as compared with PODD alone. The adsorption of the SDS/PODD mixture increased as the anionic and cationic system approached an equimolar ratio. Precipitation diagrams for mixtures of single‐ and twin‐head surfactant systems showed smaller precipitation areas than for single‐head‐only surfactant mixtures. Thus, the combination of single‐ and double‐head surfactants helps reduce the precipitation region and can increase the adsorption levels, although the magnitude of the effect is a function of the specific surfactants used.
Use of high‐active alpha olefin sulfonates in laundry powders
Authors: Raney Kirk H. , Shpakoff Paul G. , Passwater Deborah K. 
Published: November 2006

AbstractAlpha olefin sulfonates (AOS) have been used successfully for many years in laundry and personal‐care products throughout Asia. Among their documented positive attributes are good cleaning and high foaming in both soft and hard water, rapid biodegradability, and good skin mildness. AOS has commonly been marketed as approximately 40%‐active aqueous solutions. However, with the increased importance of compact powder detergents produced by processes other than spray drying, high‐active forms of AOS including 70%‐active pastes and 90+%‐active powders are now being utilized for that product sector. In this regard, the rheological properties of non‐Newtonian AOS and AOS/additive pastes at relevant process temperatures were measured and found potentially suitable for agglomeration processes. Also, the relationship of AOS powder particle size to surfactant solubility at various wash conditions was examined to allow determination of the optimal size for both detergency and processing of laundry powders. Both paste rheology and powder morphology are critical factors for the successful use of high‐active AOS in compact powder detergents.
Aging of oily soils on textiles. Chemical changes upon oxidation and interaction with textile fibers
Authors: Chi Yong‐Seung , Kay Obendorf S. 
Published: November 2006

AbstractAging of unsaturated oily soils on textile materials produces yellow compounds that are difficult to remove by washing. To investigate changes that occur in oily soils when aged, the aging of squalene and artificial sebum were studied. Proton nuclear magnetic resonance, infrated spectroscopy, gas chromatography, and gel permeation chromatography studies showed that oily soils were oxidized upon aging, forming low molecular weight products that also polymerized to higher molecular weight compounds with prolonged aging. The oxidation products contained hydroxyl, carbonyl, or ester groups. Oxidation compounds with yellow chromophores appeared to be mostly those of the 1000–2500 molecular weight fraction; though in earlier, stages of aging, lower molecular weight fractions also contained chromophores. By using glucose as a model compound of cellulose, it was found that yellow oxidation products of aged squalene were covalently bound to the substrate. Because the aging of oily soils is a free‐radical oxidation process, oxidation products having chromophores are thought to attach to the cotton substrate through radical coupling. Oily soils also showed possibilities of chemical bonding with nylon but not with polyester.
Formation kinetics and stability of surfactant vesicles
Authors: Zhang Zhiqiang , Ganzuo Li , Patel Ramesh , Friberg Stig E. , Aikens Patricia A. 
Published: November 2006

AbstractA three‐component phase diagram of a system containing water, dimethyl isosorbide and Laureth 4 (Brij® 30), a commercial surfactant, was determined, and the kinetics of vesicle formation from dilution with water of the hydrotrope solution was studied using a stop‐flow process in conjunction with light‐scattering determinations. The phase diagram consisted of a large microemulsion phase and a lamellar liquid crystalline region. Results from the stop‐flow/light‐scattering determinations were tentatively interpreted using the Aniansson‐Kahlweit‐Zana theory of micellar relaxation for a system close to equilibrium. The interpretation indicated the vesicles to be formed by monomolecular buildup for surfactant concentrations less than 5%, while for vesicles formed at greater concentrations an agglomeration of vesicle fractions appeared more reasonable.
Purification, molecular cloning, and expression of the gene encoding fatty acid 13‐hydroperoxide lyase from guava fruit (Psidium guajava)
Authors: Tijet Nathalie , Wäspi Urs , Gaskin Duncan J. H. , Hunziker Peter , Muller Bernard L. , Vulfson Evgeny N. , Slusarenko Alan , Brash Alan R. , Whitehead Ian M. 
Published: November 2006

AbstractGuava fruit was identified as a particularly rich source of 13‐hydroperoxide lyase activity. The enzyme proved stable to chromatographic procedures and was purified to homogeneity. Based on gel filtration and gel electrophoresis, the native enzyme appears to be a homotetramer with subunits of 55 kD. Starting with primers based on the peptide sequence, the enzyme was cloned by polymerase chain reaction with 3′ and 5′ rapid amplification of cDNA ends. The sequence shows approximately 60–70% identity to known 13‐hydroperoxide lyases and is classified in cytochrome P450 74B subfamily as CYP74B5. The cDNA was expressed in Escherichia coli (BL21 cells), with optimal enzyme activity obtained in the absence of isopropyl‐β‐d‐thiogalactopyranoside and σ‐aminolevulinic acid. The expressed enzyme metabolized 13(S)‐hydroperoxylinolenic acid over 10‐fold faster than 13(S)‐hydroperoxylinoleic acid and the 9‐hydroperoxides of linoleic and linolenic acids. 13(S)‐Hydroperoxylinolenic acid was converted to 12‐oxododec‐9(Z)‐enoic acid and 3(Z)‐hexenal, as identified by gas chromatography‐mass spectrometry. The turnover number with this substrate, with enzyme concentration estimated from the Soret absorbance, was≈2000/s, comparable to values reported for the related allene oxide synthases. Distinctive features of the guava 13‐hydroperoxide lyase and related cytochrome P450 are discussed.
Do glycerolipids display lateral heterogeneity in the thylakoid membrane?
Authors: Duchêne Sylvie , Siegenthaler Paul‐André 
Published: November 2006

AbstractThe lateral heterogeneity of lipids in the thylakoid membrane has been questioned for over 20 yrs. It is generally believed that glycerolipids are asymmetrically distributed within the plane of the membrane. In the present investigation, we isolated several thylakoid membrane domains by using sonication followed by separation in an aqueous dextran‐polyethylene glycol two‐phase system. This technique, which avoids detergent treatments, allowed us to obtain stroma and grana lamellae vesicles as well as grana central core and grana margin vesicles from thylakoids. The relative distribution of the four lipid classes, i.e., monogalactosyldiacylglycerol, digalactosyldiacylglycerol, sulfoquinovosyldiacylglycerol, and phosphatidylglycerol, was found to be statistically identical in all four thylakoid fractions and in whole thylakoids. Similarly, the relative amount of fatty acids in each individual lipid and the eight main phosphatidylglycerol molecular species was identical in all thylakoid membrane fractions tested as well as in the intact thylakoid membrane. Based on presently available procedures for obtaining thylakoid subfractions that are unable to discriminate microdomains within the membrane, it is concluded that glycerolipids are evenly distributed within the plane of the thylakoid membrane. These data are discussed in terms of “bulk” and “specific” lipids.
Effect of low‐to‐moderate amounts of dietary fish oil on neutrophil lipid composition and function
Authors: Healy D. A. , Wallace F. A. , Miles E. A. , Calder P. C. , Newsholme P. 
Published: November 2006

AbstractAlthough essential to host defense, neutrophils are also involved in numerous inflammatory disorders including rheumatoid arthritis. Dietary supplementation with relatively large amounts of fish oil [containing >2.6 g eicosapentaenoic acid (EPA) plus 1.4 g docosahexaenoic acid (DHA) per day] can attenuate neutrophil functions such as chemotaxis and superoxide radical production. In this study, the effects of more moderate supplementation with fish oil on neutrophil lipid composition and function were investigated. The rationale for using lower supplementary doses of fish oil was to avoid adverse gastrointestinal problems, which have been observed at high supplementary concentrations of fish oil. Healthy male volunteers aged <40 yr were randomly assigned to consume one of six dietary supplements daily for 12 wk (n=8 per treatment group). The dietary supplements included four different concentrations of fish oil (the most concentrated fish oil provided 0.58 g EPA plus 1.67 g DHA per day), linseed oil, and a placebo oil. The percentages of EPA and DHA increased (both P<0.05) in neutrophil phospholipids in a dose‐dependent manner after 4 wk of supplementation with the three most concentrated fish oil supplements. No further increases in EPA or DHA levels were observed after 4 wk. The percentage of arachidonic acid in neutrophil phospholipids decreased (P<0.05) after 12 wk supplementation with the linseed oil supplement or the two most concentrated fish oil supplements. There were no significant changes in N‐formyl‐met‐leu‐phe‐induced chemotaxis and superoxide radical production following the dietary supplementations. In conclusion, low‐to‐moderate amounts of dietary fish oil can be used to manipulate neutrophil fatty acid composition. However, this may not be accompanied by modulation of neutrophil functions such as chemotaxis and superoxide radical production.
Conjugated linoleic acid supplementation in humans: Effects on circulating leptin concentrations and appetite
Authors: Medina Edward A. , Horn William F. , Keim Nancy L. , Havel Peter J. , Benito Paloma , Kelley Darshan S. , Nelson Gary J. , Erickson Kent L. 
Published: November 2006

AbstractConjugated linoleic acid (CLA) has been demonstrated to reduce body fat in animals. However, the mechanism by which this reduction occurs is unknown. Leptin may mediate the effect of CLA to decrease body fat. We assessed the effects of 64 d of CLA supplementation (3 g/d) on circulating leptin, insulin, glucose, and lactate concentrations in healthy women. Appetite was assessed as a physiological correlate of changes in circulating leptin levels. Analysis of plasma leptin concentrations adjusted for adiposity by using fat mass as a covariate showed that CLA supplementation significantly decreased circulating leptin concentrations in the absence of any changes of fat mass. Mean leptin levels decreased over the first 7 wk and then returned to baseline levels over the last 2 wk of the study in the CLA‐treated group. Appetite parameters measured at around the time when the greatest decreases in leptin levels were observed showed no significant differences between supplementation and baseline determinations in the CLA‐supplemented group or between the CLA and placebo‐supplemented groups. There was a nonsignificant trend for mean insulin levels to increase toward the end of the supplementation period in CLA‐treated subjects. CLA did not affect plasma glucose and lactate over the treatment period. Thus, 64 d of CLA supplementation in women produced a transient decrease in leptin levels but did not alter appetite. CLA did not affect these parameters in a manner that promoted decreases of adiposity.
Perinatal characteristics may influence the outcome of visual acuity
Authors: Makrides Maria , Neumann Mark A. , Gibson Robert A. 
Published: November 2006

AbstractVisual‐evoked potential (VEP) acuity has been used to assess the effects of dietary fats on the integrity of the visual pathway of infants. We investigated prognostic determinants of VEP acuity at 16 wk of age. The results of two randomized dietary intervention trials designed to assess the effect of dietary fatty acids on the visual development of term infants were combined. At entry to both trials (∼day 5 of life), a blood sample to assess polyunsaturated fatty acid (PUFA) status was collected along with sociodemographic and perinatal characteristics. At 16±0.9 wk of age, infants underwent VEP testing to measure acuity. There was no effect of dietary treatment on these outcomes within or between trials. Multiple linear regression models were constructed to investigate the effect of perinatal and nutritional variables at study entry on VEP acuity of 185 infants. Higher birth weight was associated with an ability to resolve smaller checkerboard patterns [r2=0.05; 95% confidence interval (Cl), −0.10, −0.04 log units]. Male gender (r2=0.03; 95% Cl, 0.01, 0.07 log units), day 5 plasma 22∶5n−6 (r2=0.04; 95% Cl, 0.02, 0.20 log units), day 5 red cell membrane 20∶3n−9 (r2=0.03; 95% Cl, 0.03, 0.13 log units), and the number of smokers in the household (r2=0.02; 95% Cl, 0.00, 0.04 log units) were all associated with poorer VEP acuity scores. It is possible that a combination of perinatal factors could accumulate to either mask or enhance effects of diet on VEP acuity, given the relatively modest effects of long‐chain PUFA on visual outcome.
Polyunsaturated fatty acids and cerebral function: Focus on monoaminergic neurotransmission
Authors: Chalon Sylvie , Vancassel Sylvie , Zimmer Luc , Guilloteau Denis , Durand Georges 
Published: November 2006

AbstractMore and more reports in recent years have shown that the intake of polyunsaturated fatty acids (PUFA) constitutes an environmental factor able to act on the central nervous system (CNS) function. We recently demonstrated that the effects of PUFA on behavior can be mediated through effects on the monoaminergic neurotransmission processes. Supporting this proposal, we showed that chronic dietary deficiency in α‐linolenic acid in rats induces abnormalities in several parameters of the mesocortical and mesolimbic dopaminergic systems. In both systems, the pool of dopamine stored in presynaptic vesicles is strongly decreased. This may be due to a decrease in the number of vesicles. In addition, several other factors of dopaminergic neurotransmission are modified according to the system affected. The mesocortical system seems to be hypofunctional overall [e.g., decreased basal release of dopamine (DA) and reduced levels of dopamine D2 (DAD2) receptors]. In contrast, the mesolimbic system seems to be hyperfunctional overall (e.g., increased basal release of DA and increased levels of DAD2 receptors). These neurochemical changes are in agreement with modifications of behavior already described with this deficiency. The precise mechanisms explaining the effects of PUFA on neurotransmission remain to be clarified. For example, modifications of physical properties of the neuronal membrane, effects on proteins (receptors, transporters) enclosed in the membrane, and effects on gene expression and/or transcription might occur. Whatever the mechanism, it is therefore assumed that interactions exist among PUFA, neurotransmission, and behavior. This might be related to clinical findings. Indeed, deficits in the peripheral amounts of PUFA have been described in subjects suffering from neurological and psychiatric disorders. Involvement of the monoaminergic neurotransmission function has been demonstrated or hypothesized in several of these diseases. It can therefore be proposed that functional links exist among PUFA status, neurotransmission processes, and behavioural disorders in humans. Animal models are tools of choice for the understanding of such links. Improved prevention and complementary treatment of neurological and psychiatric diseases can be expected from these studies.
Metabolism and functions of highly unsaturated fatty acids: An update
Authors: Nakamura Manabu T. , Cho Hyekyung P. , Xu Jing , Tang Zhongren , Clarke Steven D. 
Published: November 2006

AbstractThis review briefly examines the recent progress in knowledge about the synthesis and degradation of highly unsaturated fatty acids (HUFA) and their functions. Following the cloning of mammalian Δ6‐desaturase (D6D), the D6D mRNA was found in many tissues, including adult brain, maternal organs, and fetal tissue, suggesting an active synthesis of HUFA in these tissues. The cloning also confirmed the long‐postulated hypothesis that the same pathway is followed in n−6 and n−3 HUFA synthesis. Dietary n−6 and n−3 HUFA both induce fatty acid oxidation enzymes in peroxisomes when compared to their respective precursor polyunsaturated fatty acids. This suggests that peroxisomes may be the primary site of HUFA degradation when HUFA are supplied in excess from the diet. Peroxisome proliferators strongly induce the enzymes for the HUFA synthesis. The mechanism of this induction is currently unknown. Recent studies revealed new HUFA functions that are not mediated by eicosanoids. These functions include endocytosis/exocytosis, ionchannel modulation, DNA polymerase inhibition, and regulation of gene expression. These new discoveries will enable us to reexamine the underlying mechanisms for the classical symptoms of essential fatty acid deficiency as well as vitamin E deficiency. Progress has also been made in understanding the mechanism by which dietary HUFA reduce body fat deposition. One mechanism is induction of genes for fatty acid oxidation, which is mediated by peroxisome proliferator‐activated receptor‐α. Another likely mechanism is that HUFA suppress genes for fatty acid synthesis by reducing both mRNA and protein maturation of sterol regulatory element binding protein‐1.