bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of the Hydroxyl Value of Soybean Polyol by Attenuated Total Reflectance/Fourier Transform Infrared Spectroscopy
Authors: Godoy Simone C. , Ferrão Marco Flôres , Gerbase Annelise E. 
Published: May 2007

AbstractA rapid method for the quantitative determination of the hydroxyl value (OHV) of hydroxylated soybean oils by HATR/FTIR spectroscopy is described. Calibration standards were prepared by the formic acid/hydrogen peroxide method and OH values were determined by the official method of AOCS Tx 1a‐66, covering an analytical range of 3.5–125 mg of KOH/g of sample. A partial least squares (PLS) calibration model for the prediction of the hydroxyl value (OHV) was developed based on eight different spectral subregions between 3,150 and 990 cm−1 and combinations of them. On average, 36 samples were used for the modeling and 17 were used for external validation. The resulting calibration was linear over the analytical range and had a standard deviation of 2.334. Validation of the method was carried out by comparing the OHV of a series of hydroxylated soybean oils predicted by the PLS model to the values obtained by the AOCS standard method. A correlation coefficient of R2 = 0.9843 and RMSEC and RMSEP values of, respectively, 3.393 and 3.643 were obtained. After the calibration of the spectrometer, the OHV could be obtained in 2–3 min per sample, a major improvement over conventional wet chemical methods. The advantages of these methodologies are that they do not destroy the sample, have a lower cost, expedite the analysis and do not produce residues. Therefore, they may yield excellent results when used to quantify OHV of soybean polyols obtained by hydroxylation reaction.
Thermal degradation of single methyl oleate hydroperoxides obtained by Photosensitized oxidation
Authors: Lercker Giovanni , Bortolomeazzi Renzo , Pizzale Lorena 
Published: May 2007

AbstractA peroxidation mixture containing methyl 9‐ and 10‐hydroperoxy‐trans‐octadecenoates (MOHP) was obtained by singlet oxygen oxidation of methyl oleate. The two hydroperoxides were collected by solid phase extraction and purified separately by high‐performance liquid chromatography. Identification and single‐isomer purity evaluations were carried out by comparing the chromatographic and gas chromatography‐mass spectrometry parameters of the corresponding reduced hydroxy derivatives. Each purified MOHP was thermally degraded and new reaction mechanisms were proposed from the identification of the degradation products. Thermal rearrangement of each hydroperoxide isomer involved an allylic 3‐carbon intermediate before further degradation steps. The two MOHP isomers obtained from singlet oxygen oxidation produced all eight hydroperoxide isomers by thermal degradation in the condensed phase at high temperature (200°C). This result supports the assumption of singlet oxygen as a promoter of the first steps of oxidation of food lipids and also reconsiders the Khan mechanism.
Oxidative and flavor stability of oil from lipoxygenase‐free soybeans
Authors: King J. M. , Svendsen L. K. , Fehr W. R. , Narvel J. M. , White R. J. 
Published: May 2007

AbstractSoybeans that lack or contain three lipoxygenase (LOX) isozymes, LOX‐1, LOX‐2, and LOX‐3, were evaluated for oxidative and flavor stability at 60°C in the dark and at 35°C in the light. Although the two types of soybeans had a similar genetic background, there were significant differences (P≤0.01) in fatty acid percentages between the lipoxygenase‐free and normal oils before and after storage at both temperatures. The linolenic acid content of oil from LOX‐free germplasm before storage averaged 7.2%, while normal lines averaged 6.6%. The linoleic acid content after storage averaged 6.9% for LOX‐free and 6.6% for normal oils. LOX‐free oil was not significantly different from normal oil in flavor, as judged by a sensory panel, or in concentrations of volatiles during storage at either storage condition. LOX‐free oil had less hexanal than normal oil before storage, but had significantly greater (P≤0.05) levels after storage for two weeks at 35°C. Peroxide values of oil from LOX‐free soybeans were significantly greater (P≤0.01) than oil from the normal soybean after storage at 60 and 35°C. LOX‐free oil had significantly greater (P≤0.01) levels of α‐, β‐, and γ‐tocopherols. In general, oil from LOX‐free soybeans did not have improved flavor or oxidative stability. Differences between the two oil types in peroxide value and in production of a few volatiles were probably a result of the differences in initial fatty acid composition.
Effects of processing on the oxidative stability of soybean oil produced in Mexico
Authors: Medina‐Juárez L. A. , González‐Díaz P. , Gámez‐Meza N. , Ortega‐García J. , Moreno‐Varela A. B. , Bringas‐Alvarado L. , Angulo‐Guerrero O. 
Published: May 2007

AbstractThe stability parameters of 22 samples of soybean oil produced in Mexico were determined. Samples were analyzed for moisture, color, free fatty acids, peroxide value, p‐anisidine value, fatty acid profile, metals, flavor, and Rancimat test for oxidative stability. Results obtained were compared with the stability parameters of soybean oil sproduced in the United States and Costa Rica. The fatty acid profile in all samples analyzed corresponded to the expected profile for a 100% soybean oil. Sixty‐four percent of the oils had oxidative stabilities similar to those reported for soybean oils from the United States and Costa Rica. This suggests that in spite of the good quality, the soybean oil production process in Mexico needs further improvement. Especially important is maintaining appropriate control during the degumming and bleaching steps. Special consideration should be given to preserving the natural antioxidants present in the oil.
Preparation of malvalic and sterculic acid methyl esters from Bombax munguba and Sterculia foetida seed oils
Authors: Fehling E. , Schönwiese S. , Klein E. , Mukherjee K. D. , Weber N. 
Published: May 2007

AbstractA method has been developed for the preparation of highly pure malvalic (cis‐8,9‐methyleneheptadec‐8‐enoic) and sterculic (cis‐9,10‐methyleneoctadec‐9‐enoic) acid methyl esters starting from Bombax munguba and Sterculia foetida seed oils. The methyl esters of these oils were prepared by sodium methylate‐catalyzed transmethylation followed by cooling (6°C) the hexane solution of crude methyl esters and separation of insoluble fatty acid methyl esters by centrifugation in the case of B. munguba and by column chromatography in the case of S. foetida. Subsequently, the saturated straight‐chain fatty acid methyl esters were almost quantitatively removed by urea adduct formation. Finally, methyl malvalate and methyl sterculate were separated from the remaining unsaturated fatty acid methyl esters, in particular methyl oleate and methyl linoleate, by preparative high‐performance liquid chromatography on C18 reversed‐phase using acetonitrile isocratically. Methyl malvalate and methyl sterculate were obtained with purities of 95–97 and 95–98%, respectively.
The effect of immobilization on the hydrolytic/interesterification activity of lipase from Rhizopus niveus
Authors: Kermasha S. , Bisakowski B. 
Published: May 2007

AbstractLipase from Rhizopus niveus was immobilized by physical adsorption on Celite 545 and glass beads. The results showed that the highest immobilization efficiency and specific hydrolytic activity of 96% and 9.2 meq/mg protein/min, respectively, were obtained with Celite as the carrier. However, the specific hydrolytic activity of lipase adsorbed on glass beads by acetone precipitation was similar to that obtained by the Celite carrier, although the protein loading capacity was relatively low. The results showed that lipase immobilized on glass beads exhibited similar activity profiles with respect to reaction time, different enzyme concentrations, and water content, using trimyristin and tripalmitin as substrates, to those obtained with the free enzyme. In contrast, the immobilized lipase on Celite exhibited a considerably lower hydrolytic activity. However, the results also showed that the lipase activities of the free enzyme and the immobilized Celite enzyme were similar when the more hydrophilic triolein was used as the substrate. The interesterification of a mixture of tripalmitin and trimyristin or triolein was carried out using both the free and immobilized enzymes. The results indicated that the hydrolytic activity of lipase was similar in both cases for the first 24 h, after which it decreased dramatically. These findings suggest that at this late stage an equilibrium between the hydrolytic and interesterification reactions was reached.
The influence of trace components on the melting point of methyl soyate
Authors: Yu Liangping , Lee Inmok , Hammond Earl G. , Johnson Lawrence A. , Van Gerpen Jon H. 
Published: May 2007

AbstractThe objective of this study was to determine the effect of various amounts of unsaponifiables and bound glycerol on the crystallization temperatures of methyl soyate used as biodiesel. The preparation of methyl esters did not affect the amount of unsaponifiable matter in biodiesel. A synthetic unsaponifiable mixture added to distilled methyl soyate and blends of methyl soyate and No. 1 diesel fuel (20:80, vol/vol) did not affect the crystallization onset temperature, cloud point, or pour point at concentrations up to 3% by weight. The amounts of monoglycerides and diglycerides in methyl soyate decreased from 2.60 and 9.87%, respectively, to 0% as the methanol/soybean oil ratio increased from 90 to 200% of the theoretical requirement. Transesterification reactions conducted with less than 130% of the theoretical amount of methanol resulted in methyl soyate with a higher cloud point because of the presence of saturated mono‐ and diglycerides. Pure mono‐ and diglycerides added to distilled methyl soyate at 0 to 1.0% did not change the pour point of the esters, but the cloud point of esters increased with increasing amount of saturated mono‐ or diglyceride. Pure saturated mono‐ or diglyceride presented in concentrations as low as 0.1% increased the cloud point of methyl soyate. Similar results were obtained with mono‐ and diglyceride mixtures present in incompletely converted methyl soyate.
Synthesis, mass spectrometry, and nuclear magnetic resonance characterization of Di‐guerbet esters
Authors: Knothe Gerhard , Carlson Kenneth D. 
Published: May 2007

AbstractSeveral Di‐Guerbet esters (DGE) suitable for lubricant applications were synthesized from branched Guerbet alcohols and Guerbet acids. The mass spectra of DGE under electron‐ionization and positive chemical‐ionization (PCI) conditions were recorded. Gas chromatography‐mass spectrometry, especially in PCI mode with methane as reagent gas, is an effective method for analyzing DGE. In methane positive chemical‐ionization mass spectrometry, the DGE give molecular ion peaks. In both PCI and EI modes, some other characteristic ions including up to four McLafferty rearrangement products with high m/z are observed. Thus identification of both hydrocarbon moieties is possible. The DGE were also characterized by 1H‐and 13C nuclear magnetic resonance.
Oxidative stability of polyunsaturated fatty acids and soybean oil in an aqueous solution with emulsifiers
Authors: Duh Pin‐Der , Yen Wen Jye , Yen Gow‐Chin 
Published: May 2007

AbstractThe oxidative stability of polyunsaturated fatty acids (PUFA) and soybean oil homogenized with emulsifiers was investigated. Model emulsions were prepared from PUFA, including linoleic acid (LA), arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), and from soybean oil emulsified with different emulsifiers: three Tween emulsifiers (Tween 20, Tween 60, Tween 80) and two sucrose esters (S‐1170 and S‐1570) were used. The results showed that the emulsions prepared from LA and the various emulsifiers, oxidized at 40°C, were unstable. However, the corresponding AA, EPA, and DHA emulsions were stable, indicating that PUFA with a higher degree of unsaturation were more stable with emulsifiers than without the emulsifiers. In the soybean oil‐in‐water model system, the oxidation of soybean oil with various emulsifiers was less than without the emulsifiers.
Static headspace gas chromatographic analyses to determine oxidation of fish muscle lipids during thermal processing
Authors: Medina I. , Satué‐Gracia M. T. , Frankel E. N. 
Published: May 2007

AbstractOxidation in fish during thermal processing was studied by determining volatile production with a static headspace gas chromatographic system. Different processing temperatures and periods were evaluated to simulate conditions of fish industrial treatments. The major volatiles formed included acetaldehyde, propanal, heptane, 2‐ethylfuran, pentanal, and hexanal. Changes in volatile composition were studied for different processing times and temperatures. The method for volatile analyses to determine oxidation in fish muscle was tested by correlation with peroxide value, conjugated diene, and thiobarbituric acid indices. Significant single and multivariate regressions were found between the time of thermal treatment and volatiles produced, showing that the amount of 2‐ethylfuran was the best predictor of oxidative stability in fish.
The association of betaine, homocysteine and related metabolites with cognitive function in Dutch elderly people
Authors: Eussen Simone J. P. M. , Ueland Per M. , Clarke Robert , Blom Henk J. , Hoefnagels Willibrord H. L. , van Staveren Wija A. , de Groot Lisette C. P. G. M. 
Published: May 2007

The importance of the one-carbon metabolites, choline and homocysteine, to brain function is well known. However, the associations between the one-carbon metabolites choline, betaine, methionine and dimethylglycine with cognition in elderly are unclear. We therefore examined the associations of these metabolites with cognition in a double-blind, placebo-controlled trial. Individuals (n 195) were randomized to receive daily oral capsules with either 1000 μg cobalamin (vitamin B12), or 1000 μg cobalamin plus 400 μg folic acid, or placebo for 24 weeks. Concentrations of homocysteine, methionine, choline, betaine and dimethylglycine were assessed before and after 12 and 24 weeks of treatment. Cognitive function, including domains of attention, construction, sensomotor speed, memory and executive function, was assessed before and after 24 weeks of treatment. At baseline, elevated plasma homocysteine was associated with lower performance of attention, construction, sensomotor speed and executive function. In addition, betaine was positively associated with better performance of construction, sensomotor speed and executive function, whereas elevated concentrations of methionine were positively associated with sensomotor speed. Daily combined supplementation with cobalamin plus folic acid decreased total homocysteine concentrations by 36 %, and increased betaine concentrations by 38 %. Participants with the largest increases in betaine concentrations showed a borderline significant (P = 0·07) higher memory performance compared to those without it. Although this trial observed associations of homocysteine and betaine with cognitive domains prior to supplementation, decreased concentrations of homocysteine were not related to improved cognitive performance. There was a tendency of participants with the largest increases in betaine concentrations to show the greatest improvement in memory function.
Within-field variation in grain yield, yield components and quality traits of two-row barley
Authors: RAJALA A. , PELTONEN-SAINIO P. , KAUPPILA R. , WILHELMSON A. , REINIKAINEN P. , KLEEMOLA J. 
Published: May 2007

SUMMARYRecent studies of precision cereal farming systems have documented large within-field and annual variation in grain yield and quality. The principal aim of the present study was to evaluate the degree of within- and between-field variation in biomass, yield, yield component structure and quality traits, such as grain protein of two-row barley (Hordeum vulgare L.), using crop samples collected from field patches of varying yield potential. Plant samples were collected from the fields of commercial farmers located in southern Finland in 2000 and 2001. Selection of low, intermediate and high yielding patches for crop sampling was based on aerial infrared colour images taken twice during the growing season. When stands were mature, plant samples from an area of 0·5 m2 were uprooted for yield component and quality analysis. Nitrogen accumulation prior to heading was strongly associated with biomass accumulation, indicating differences in growth potential of the different field patches. The principal yield determining trait in two-row barley was grain number/m2, whereas single grain weight (SGW) had a lesser effect on grain yield. The degree of variation in the quality parameters, namely protein and SGW, was not associated with grain yield. This suggests that within-field variation in yield potential does not determine heterogeneity of the grain yield in terms of grain weight or grain protein content.
Lagrangian statistics of Navier–Stokes and MHD turbulence
Authors: HOMANN H. , GRAUER R. , BUSSE A. , MÜLLER W. C. 
Published: May 2007

AbstractWe report on a comparison of high-resolution numerical simulations of Lagrangian particles advected by incompressible turbulent hydro- and magnetohydrodynamic (MHD) flows. Numerical simulations were performed with up to 10243 collocation points and 10 million particles in the Navier–Stokes case and 5123 collocation points and 1 million particles in the MHD case. In the hydrodynamics case our findings compare with recent experiments from Mordant et al. (2004 New J. Phys.6, 116) and Xu et al. (2006 Phys. Rev. Lett.96, 024503). They differ from the simulations of Biferale et al. (2004 Phys. Rev. Lett.93, 064502) due to differences of the ranges chosen for evaluating the structure functions. In Navier–Stokes turbulence intermittency is stronger than predicted by the multifractal approach of Biferale et al. (2004 Phys. Rev. Lett.93, 064502) whereas in MHD turbulence the predictions from the multifractal approach are more intermittent than observed in our simulations. In addition, our simulations reveal that Lagrangian Navier–Stokes turbulence is more intermittent than MHD turbulence, whereas the situation is reversed in the Eulerian case. Those findings can not consistently be described by the multifractal modeling. The crucial point is that the geometry of the dissipative structures have different implications for Lagrangian and Eulerian intermittency. Application of the multifractal approach for the modeling of the acceleration probability density functions works well for the Navier–Stokes case but in the MHD case just the tails are well described.
Reaction time performance in ADHD: improvement under fast-incentive condition and familial effects
Authors: ANDREOU PENNY , NEALE BEN M. , CHEN WAI , CHRISTIANSEN HANNA , GABRIELS ISABEL , HEISE ALEXANDER , MEIDAD SHEERA , MULLER UELI C. , UEBEL HENRIK , BANASCHEWSKI TOBIAS , MANOR IRIS , OADES ROBERT , ROEYERS HERBERT , ROTHENBERGER ARIBERT , SHAM PAK , STEINHAUSEN HANS-CHRISTOPH , ASHERSON PHILIP , KUNTSI JONNA 
Published: May 2007

ABSTRACTBackgroundReaction time (RT) variability is one of the strongest findings to emerge in cognitive-experimental research of attention deficit hyperactivity disorder (ADHD). We set out to confirm the association between ADHD and slow and variable RTs and investigate the degree to which RT performance improves under fast event rate and incentives. Using a group familial correlation approach, we tested the hypothesis that there are shared familial effects on RT performance and ADHD.MethodA total of 144 ADHD combined-type probands, 125 siblings of the ADHD probands and 60 control participants, ages 6–18, performed a four-choice RT task with baseline and fast-incentive conditions.ResultsADHD was associated with slow and variable RTs, and with greater improvement in speed and RT variability from baseline to fast-incentive condition. RT performance showed shared familial influences with ADHD. Under the assumption that the familial effects represent genetic influences, the proportion of the phenotypic correlation due to shared familial influences was estimated as 60–70%.ConclusionsThe data are inconsistent with models that consider RT variability as reflecting a stable cognitive deficit in ADHD, but instead emphasize the extent to which energetic or motivational factors can have a greater effect on RT performance in ADHD. The findings support the role of RT variability as an endophenotype mediating the link between genes and ADHD.
Genetic and environmental factors affecting self-esteem from age 14 to 17: a longitudinal study of Finnish twins
Authors: RAEVUORI ANU , DICK DANIELLE M. , KESKI-RAHKONEN ANNA , PULKKINEN LEA , ROSE RICHARD J. , RISSANEN AILA , KAPRIO JAAKKO , VIKEN RICHARD J. , SILVENTOINEN KARRI 
Published: May 2007

ABSTRACTBackgroundWe analysed genetic and environmental influences on self-esteem and its stability in adolescence.MethodFinnish twins born in 1983–1987 were assessed by questionnaire at ages 14 (n=4132 twin individuals) and 17 years (n=3841 twin individuals). Self-esteem was measured using the Rosenberg global self-esteem scale and analyzed using quantitative genetic methods for twin data in the Mx statistical package.ResultsThe heritability of self-esteem was 0·62 [95% confidence interval (CI) 0·56–0·68] in 14-year-old boys and 0·40 (95% CI 0·26–0·54) in 14-year-old girls, while the corresponding estimates at age 17 were 0·48 (95% CI 0·39–0·56) and 0·29 (95% CI 0·11–0·45). Rosenberg self-esteem scores at ages 14 and 17 were modestly correlated (r=0·44 in boys,r=0·46 in girls). In boys, the correlation was mainly (82%) due to genetic factors, with residual co-variation due to unique environment. In girls, genetic (31%) and common environmental (61%) factors largely explained the correlation.ConclusionsIn adolescence, self-esteem seems to be differently regulated in boysversusgirls. A key challenge for future research is to identify environmental influences contributing to self-esteem during adolescence and determine how these factors interact with genetic influences.
Actuarial prediction of violent recidivism in mentally disordered offenders
Authors: SNOWDEN ROBERT J. , GRAY NICOLA S. , TAYLOR JOHN , MacCULLOCH MALCOLM J. 
Published: May 2007

ABSTRACTBackgroundActuarial instruments may be useful in predicting long-term violence in mentally disordered patients. We compared two instruments that differ in terms of what they are designed to predict (generalversusviolent recividism) and the inclusion of stable mental health variables.MethodA large sample of mentally disordered patients were scored on two risk assessment instruments, the Violence Risk Appraisal Guide (VRAG) and the Offender Group Reconviction Scale (OGRS), based on information at the point of discharge. Their criminal histories for at least 2 years following discharge were obtained from official records.ResultsBoth instruments were good predictors of both violent and general offending. Over shorter periods (<1 year) the VRAG had very good predictive validities for both types of offences [areas under the receiver operating characteristic curves (AUCs) >0·85], which were significantly better than the OGRS. For longer follow-up periods the instruments had approximately equal prediction accuracy. However, both instruments predicted far more offences than were in fact recorded.ConclusionsThe VRAG is a very good predictor of future violence in the UK sample. The OGRS may also be of value as it can be completed quickly and without the need for mental health variables. Caution is needed, however, as both instruments appeared to over-predict the levels of reconvictions in this sample.