bluuebunny/crossref_metadata_2025_split huggingface dataset:
Negative long wavelength dielectric constant in semiconductor QWs
Authors: Hessami Pilehrood S. , Gao Feng , Ma Zhongshui , Xu Wen , Zhang Chao 
Published: February 2007

AbstractIn this work we present an analytical and numerical result of the dielectric function of electronic systems with Rashba spin‐orbit interaction. By solving the quantum equation of motion for the electron density matrix, we obtained the dielectric function in the mean‐field approximation. It is shown that when the momentum transfer q for an electronic transition is smaller than a critical value characterized by the spin‐orbit interaction, the static dielectric function increases with q, indicating on‐set of a new collective state. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin Josephson effect in spintronic nanostructures
Authors: Ma Zhongshui , Xu Wen , Zhang Chao 
Published: February 2007

AbstractThe problem of spin current across a ferromagnetic/normal metal/ferromagnetic junction is formulated. It is shown that the spin current is controlled by the phase difference across the junction. Under zero bias, Jz is time‐independent and Jz is sinusoidal function, where Jz is the Sz current along z ‐direction. Under a dc bias, Jz and |Jz + iJz | are sinusoidal and the phase of the latter is in front by π. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum interference through parallel‐coupled Double Quantum Dots
Authors: Lu Haizhou , Chen Zuo‐zi , Lü Rong , Zhu Bang‐fen 
Published: February 2007

AbstractThe electronic transport is theoretically studied through a double quantum dot (DQD) system. With focus on the effects of the on‐dot Coulomb repulsion U or the electron‐phonon interaction (EPI) on the quantum interference in the parallel DQD, we find that if U is comparable with level separation in the parallel‐coupled DQD, a new type of Fano interference between U ‐hybridized channels in the conductance spectra may appear and show new features; and if the EPI is significant only in one channel, as a prober of “which path” in quantum mechanics, the phonon channel won't interfere with the no‐EPI channel. A closely related transport experiment is proposed to verify the prediction. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
State‐feedback stabilization for high‐order stochastic nonlinear systems with stochastic inverse dynamics
Authors: Xie Xue‐Jun , Tian Jie 
Published: February 2007

AbstractFor a class of high‐order stochastic nonlinear systems with stochastic inverse dynamics which are neither necessarily feedback linearizable nor affine in the control input, this paper investigates the problem of state‐feedback stabilization for the first time. Under some weaker assumptions, a smooth state‐feedback controller is designed, which ensures that the closed‐loop system has an almost surely unique solution on [0, ∞), the equilibrium at the origin of the closed‐loop system is globally asymptotically stable in probability, and the states can be regulated to the origin almost surely. A simulation example demonstrates the control scheme. Copyright © 2007 John Wiley & Sons, Ltd.
Counting connected graphs and hypergraphs via the probabilistic method
Authors: Coja‐Oghlan Amin , Moore Cristopher , Sanwalani Vishal 
Published: February 2007

AbstractWhile it is exponentially unlikely that a sparse random graph or hypergraph is connected, with probability 1 − o(1) such a graph has a “giant component” that, given its numbers of edges and vertices, is a uniformly distributed connected graph. This simple observation allows us to estimate the number of connected graphs, and more generally the number of connected d‐uniform hypergraphs, on n vertices with ((d − 1)−1 + ε)n ≤ m = o(nlnn) edges, where ε > 0 is arbitrarily small but independent of n. We also estimate the probability that a binomial random hypergraph Hd(n,p) is connected, and determine the expected number of edges of Hd(n,p) given that it is connected. This extends prior work of Bender et al. (Random Struct Algorithm 1 (1990), 127–169) on the number of connected graphs. While Bender et al. (1990) is based on a recursion relation satisfied by the number of connected graphs, so that the argument is to some extent enumerative, we present a purely probabilistic approach. © 2007 Wiley Periodicals, Inc. Random Struct., 2007
Der Ersatzneubau des Schwebeträgers Hochdonn – Konzepte und Realisierung
Authors: Roßmeier Peter , Heiland Uwe , Pfeiffer Michael 
Published: February 2007

AbstractDer Aufsatz behandelt die Ausführung des Ersatzneubaus des Schwebeträgers der Eisenbahnhochbrücke Hochdonn über den Nord‐Ostsee‐Kanal bei Hochdonn. Für die Planung, Konstruktion, Fertigung und Montage einer 121 m langen Fachwerkbrücke, die unter komplizierten Randbedingungen in ca. 40 m über einer Wasserstraße aus‐ und einzubauen war, standen weniger als 11 Monate Ausführungszeit zur Verfügung. Die Aufgabe war bestimmt durch die kurzen Zeitfenster der Sperrungen des Nord‐Ostsee‐Kanals und der Eisenbahnstrecke Elmshorn–Westerland für die Demontage‐ und Montagevorgänge. Darüber hinaus wurde der planerische, logistische und sonstige Aufwand dadurch erhöht, daß die Demontage und Montage nicht wie geplant und beauftragt mittels Schwimmkran durchgeführt werden konnte, da der für den Einsatz vorgesehene Schwimmkran zum Zeitpunkt der Sperrungen des Kanals nicht zur Verfügung stand.
Ganzheitliche Wirtschaftlichkeitsbetrachtungen bei Verbundbrücken unter Berücksichtigung des Bauverfahrens und der Nutzungsdauer
Authors: Kuhlmann Ulrike , Pelke Eberhard , Hauf Gunter , Herrmann Torsten , Steiner Josef , Aul Michael 
Published: February 2007

AbstractFür ausgewählte Brückentypen werden verschiedene Möglichkeiten der ganzheitlichen Wirtschaftlichkeitsuntersuchung durchgeführt. Hierbei werden nicht nur die Herstellkosten, sondern ebenso die Kosten für den Betrieb, Unterhalt und die Sanierung berücksichtigt. Im Vergleich werden besonders auch verschiedene Varianten von Bauverfahren bewertet und die Kosten über die gesamte Nutzungsdauer ermittelt.Durch die Untersuchung sollen Entwurfs‐ und Entscheidungshilfen geschaffen werden, Kostenangebote zu werten und die Kriterien für die Bewertung eines Bauwerks über die reinen Herstellungskosten zu erweitern. Dieser Beitrag beruht auf einem Gutachten, das für die Hessische Straßen‐ und Verkehrsverwaltung im Rahmen des hessischen Großprojektes “Staufreies Hessen 2015” erarbeitet wurde.
Short‐term hydropower planning coordinated with wind power in areas with congestion problems
Authors: Matevosyan Julija , Söder Lennart 
Published: February 2007

AbstractIn this paper, a day‐ahead planning algorithm for a multi‐reservoir hydropower system coordinated with wind power is developed. Coordination applies to real situations, where wind power and hydropower are owned by different utilities, sharing the same transmission lines, although hydropower has priority for transmission capacity. Coordination is thus necessary to minimize wind energy curtailments during congestion situations. The planning algorithm accounts for the uncertainty of wind power forecast. Only planning for the spot market is considered. Once the production bid is placed on the market, it cannot be changed. The solution of the stochastic optimization problem should, therefore, fulfill the transmission constraints for all wind power production scenarios. An evaluation algorithm is also developed to quantify the impact from the coordinated planning in the long run. The developed planning algorithm and the evaluation algorithm are applied in a case study. The results are compared with uncoordinated operation. The results of the case study show that coordination with wind power brings additional income to the hydropower utility and leads to significant reduction of wind energy curtailments. Copyright © 2007 John Wiley & Sons, Ltd.
Separation of instrumental and chemical errors in the analysis of oils by gas chromatography—A collaborative evaluation
Authors: Craske John D. 
Published: February 2007

Thirty‐five analysts studied the concept that, in the gas chromatographic (GC) analysis of fatty acid composition, errors can be separated into those caused by poor chromatograph optimization and those related to inefficient conversion of triacylglycerols (TAG) to fatty acid methyl esters (FAME). A primary standard mixture of FAME was used to determine how well the participants had optimized their chromatographs. A primary standard of the equivalent TAG was used to determine total error of analysis. “Chemistry error” was calculated as the difference between the absolute errors found for the FAME and the TAG standards. Grades of analysis were computed for the FAME and TAG results and for the chemistry errors calculated from these analyses.Only four analysts achieved grades of analysis for the FAME standard that can be considered excellent or good. These four analysts used different injector/column configurations, indicating that, when properly optimized, a GC with a flame ionization detector is an extremely accurate instrument. Conversely, it is evident that there is the potential for most analysts to improve their instrumental optimization. In agreement with published information, AOCS method Ce 2‐66 and AOAC method 969.33 gave low chemistry grades, but a number of analysts used modifications of these methods, and some achieved much better grades. It would appear that many of the standard methods that are in common use are capable of producing improved results, but that critical parameters need to be better specified to ensure minimization of error. The concept of separating errors into those of instrument origin and those caused by the chemical component of the total method would appear to be a useful concept for the validation of analytical methods.
Cobaltothiocyanate colorimetric analysis for homologous polyoxyethylated alkyl amides
Authors: Lin John T. , Cornell Donald G. , Micich Thomas J. 
Published: February 2007

AbstractCobaltothiocyanate colorimetry has been used for quantitative analysis of polyethoxylates in biodegradation and environmental studies. Usually, the calibration parameters (slope and intercept of a calibration line) for the cobaltothiocyanate colorimetry are dependent on ethylene oxide chain length. To make the colorimetric method useful for polyoxyethylated surfactant mixtures, where the average chain length is polydispersed, a condition was found yielding parameters independent of chain length in a homologous series of polyethoxylates within a limited chain length range. The dependency can be correlated to the thermodynamics of the ethylene oxide‐cobaltothiocyanate complexation and the solvent extraction.
Effect of dietary fat upon aflatoxicosis in rats fed torula yeast containing diet
Authors: Wells P. , Aftergood L. , Parkin L. , Alfin‐Slater R. B. 
Published: February 2007

AbstractThis study was designed to study the possible interrelationships between Torula yeast, vitamin E, and the dietary fat source on aflatoxin‐induced tumors. Rats were fed Torula yeast‐containing basal diets which included 1.7 ppm aflatoxin B1 with either lard, corn oil or no fat, and with or without vitamin E supplements for 3 months. Thereafter, the respective diets without aflatoxin were fed for ca. 9 months. Animals receiving the vitamin E‐deficient diets had a high mortality. Although the vitamin E‐deficient, aflatoxin‐treated rats had lower wt gains than did the vitamin E‐deficient controls, they lived twice as long. In addition, regardless of the dietary fat source, the kidneys and adrenals of these vitamin E‐deficient, aflatoxin‐supplemented rats were found to be significantly heavier than the controls, and plasma cholesterol levels were elevated. Increased amounts of liver lipid were observed in response to aflatoxin in both corn oil‐fed and fat‐deficient rats. No such differences were observed in the responses of the vitamin E‐supplemented groups to aflatoxin. On the corn oil diet, aflatoxin administration resulted in an increased deposition of polyunsaturated fatty acids in cholesteryl ester and phospholipid fractions in livers of vitamin E‐deficient rats and the phospholipid fraction of vitamin E‐sufficient rats. The vitamin E‐deficient rats exhibited necrosis of the liver, which was alleviated when aflatoxin was included in the diet, and calcification of the kidneys, which was potentiated by the dietary aflatoxin. No tumors were observed in these animals. In animals maintained on vitamin E‐sufficient diets for 1 year, growth was depressed as a result of aflatoxin administration with the greatest depression occurring in the group fed corn oil. Spleen wt were decreased in all groups given aflatoxin. However, there were no changes in either plasma or liver cholesterol or total liver lipids which could be attributed to aflatoxin administration. When aflatoxin was fed with lard, the cholesteryl ester, triglyceride, and free fatty acid fractions of plasma had decreased amounts of the C20:4 acid. In the cholesteryl ester fraction only, this change was accompanied by increased levels of C16:0, C18:0, and C18:1 acids. In the liver phospholipids, there were increased levels of mono‐ and polyunsaturated fatty acids and decreases in the saturated fatty acids. All of the animals receiving aflatoxin exhibited severe necrosis and tumor formation in the kidneys; the animals fed lard had the highest level of involvement and those in the fat‐free group the least. Liver pathology was the least marked among the rats fed the fat‐free diet. Since aflatoxin‐induced tumors are rich in lipids, the fat‐free diet may be protective to the animal.
Selective hydrogenation of soybean oil in the presence of copper catalysts
Authors: Okkerse C. , de Jonge A. , Coenen J. W. E. , Rozendaal A. 
Published: February 2007

AbstractMany investigators associate the poor keeping properties of soybean oil with its linolenic acid content. On the other hand the high linoleic acid content is a desired property from a nutritional point of view. We have therefore developed a process for the preferential reduction of the linolenic acid content by selective hydrogenation. Conventional catalysts for the hydrogenation of fats have a rather low selectivity in this respect. When linolenic acid in soybean oil is hardened (e.g., with a nickel catalyst), most of the linoleic acid is converted into less unsaturated acids.It was found that linolenic acid is hydrogenated much more preferentially in the presence of copper catalysts than in that of nickel and other hydrogenation catalysts. At a linolenic acid content of 2%, soybean oil hardened with nickel catalyst contained about 28% linoleic acid, whereas with copper catalyst the hardened soybean oil contained 49% linoleic acid.By means of our process it is possible to manufacture a good keepable oil of, e.g., I.V. 115 and containing 1% linolenic acid and 46% linoleic acid. The storage stability of this product is comparable with that of sunflower‐seed oil. A liquid phase yield of 86% is obtained after winterization at 5C for 18 hr.The high selectivity for linolenate reduction of copper catalysts must be ascribed to the copper part of the catalyst. Investigations into the structure of the catalyst indicate that the active center consists of copper metal crystallites; whether these centers are promoted by the carrier or traces of other substances is under investigation.
Worksoftening of margarine and shortening
Authors: Haighton A. J. 
Published: February 2007

AbstractMargarine and butter have a certain yield value which is mainly determined by the fact that the fat crystals do not move in respect of each other but are fixed in a tridimensional network. The permanent network greatly contributes to the total hardness (60舑80%). This contribution can be determined by kneading the sample isothermally and by measuring the hardness before and after kneading. The decrease in hardness is called the 舠structural hardness舡 and the relative decrease the 舠worksoftening.舡 These values give a certain impression of the plasticity of the product at a certain hardness, while the Spreadability Index, which can be calculated from the structural hardness and the worksoftening, is a good measure for spreadability.
Composition and positional distribution of fatty acids in phospholipids isolated from pork muscle tissues
Authors: Kuchmak M. , Dugan L. R. 
Published: February 2007

AbstractThe composition and positional distribution of fatty acids in phospholipids isolated from four locations of a hog carcass is presented. Variations in fatty acid composition of phospholipids were found depending upon the location in the carcass. The total unsaturated fatty acid content averaged 34.3 mole % for lecithin, 52.5 mole % for phosphatidylethanolamine, 40.3 mole % for phosphatidylserine and 41.3 mole % in sphingomyelin. The cephalins had a much higher percentage of polyunsaturated fatty acids than lecithin. The chief saturated fatty acid in lecithin and sphingomyelin was palmitic and in cephalins it was stearic. A snake venom enzyme preparation(Crotalus adamanteus) hydrolyzed primarily unsaturated fatty acids in phosphoglycerides and the higher the percentage of unsaturation within the fatty acid the higher percentage of hydrolysis occurred. The unsaturated fatty acids were found chiefly at the theॆ‐position and the saturated fatty acids at thea‐position in the phosphoglycerides.
Hydrocarbons in irradiated beef and methyl oleate
Authors: Merritt Charles , Walsh J. T. , Bazinet M. L. , Kramer R. E. , Bresnick S. R. 
Published: February 2007

AbstractThe presence of hydrocarbons among the volatile compounds in food products, particularly in irradiated meat, was first discovered by Merritt and his co‐workers in 1959 (5,6). It is the purpose of this paper to focus wider attention on this significant discovery and to report briefly on new work which relates the formation of hydrocarbons in irradiated meat to lipids.
Optimizing rooting of jojoba stem cuttings: Effects of basal wounding, rooting medium and depth of insertion in medium
Authors: Palzkill David A. , Feldman William R. 
Published: February 2007

AbstractSeedling populations of jojoba are extremely heterogeneous; about 50% of the plants are nonproducing males, and many of the females are low‐yielding or are otherwise undesirable. Asexual propagation methods allow the increase and use of only desirable plants. Rooting of stem cuttings is the most commonly used asexual method; however, unsatisfactory results sometimes still occur when using this method, so it requires further refinement. In this study, three factors suspected to play an important role were studied: rooting medium, basal wounding and depth of insertion in the medium. Three media [perlite/vermiculite, 1:1 (vol/vol); peat/perlite/vermiculite, 1:1:1 and peat/perlite, 1:1], woundingvs. not wounding, and insertion of one or two nodes below the surface of the medium were compared. The base (2.5 cm) of each cutting was treated with potassium salt of indole butyric acid, 1000 ppm prior to insertion into the medium, and cuttings were rooted on a heated propagation bench under intermittent mist. The experimental design was a 3×2×2 factorial and was replicated five times. Sixteen cuttings were used per experimental unit. The study was repeated. Rooting percentage was significantly affected only in the first repetition and then only by media. The peat/perlite medium resulted in significantly less rooting than did the other two media. However, averaged over both repetitions, rooting averaged 74% for perlite/vermiculite, 78% for peat/perlite/vermiculite and 64% for peat/perlite. Depth of insertion and wounding did not affect rooting percent in either repetition of the study. Both deeper insertion and wounding resulted in roots emerging from along a greater length of the stem at the basal end of the cuttings. Cuttings with two nodes inserted into the medium averaged root emergence along a 54% greater length of the stem than those with only one node inserted. With wounding, roots emerged along 17.3 mm of the stem, while without wounding, emergence occurred only along 7.0 mm of the stem. The better root system resulting from wounding and deeper insertion into the medium would likely result in better performance of the cutting when transplanted to a field.
Productivity and cytogenetic characteristics of guayule. Screening of plants from the mapimi region
Authors: de Rodriguez Diana Jasso , Sánchez José Luis Angulo , Godina Francisca Ramirez , Reza Regino Morones , Garcia Raúl Rodríguez 
Published: February 2007

AbstractGuayule plants were screened in the region of Mapimi (Durango, Mexico) to evaluate physicochemical parameters for selection of increased productivity. The objective was to characterize rubber, and resin content, stem diameter, rubber molecular weight and cytology of these plants to identify and select high productivity sites. Samples were collected from nine locations within the Mapimi Region. Inflorescences containing young floral buds of the same plants were selected to determine ploidy level. Cytogenetic results showed the presence of di‐, tri‐ and tetraploids. Samples for rubber and resin analysis were cut from the branches. Genetic variation in molecular weight and molecular weight distributions for rubber was measured. Significant differences were found in resin content and stem diameter between the sampling sites, but differences were not significant for the rubber content between sites. A productivity parameter was defined and used to identify two locations where guayule genotypes exhibited the best characteristics for commercialization. This information may increase the industrial development and understanding of the polymerization bioprocess.
Response of direct‐seeded guayule to preemergence herbicides
Authors: Foster M. A. , Kleine L. G. , Moore J. 
Published: February 2007

AbstractDirect‐seeding guayule (Parthenium argentatum Gray) in west Texas has been successful; however, seedlings grow slowly and are extremely susceptible to weed competition. An effective preplant or preemergence herbicide is necessary for establishment. The objective of this study was to examine the effects of preemergence herbicides on guayule stand establishment by direct seeding. Experiments were initiated on a Dalby clay in 1991 and 1992 at the Texas Agricultural Experiment Station Guayule Research Site near Fort Stockton, Texas. Conditioned guayule seed (Mexican Bulk) was planted 10 mm deep on raised beds with a Gaspardo SV255 pneumatic planter at 100 seeds/m. The following herbicides were applied immediately after planting: dimethyl 2,3,5,6‐tetrachloro‐1,4‐benzenedicarboxylate (DCPA) [4.5, 9.0, 11.0 kg ai/ha (hectare)], pendimethalin [N‐(1‐ethylpropyl)‐3,4‐dimethyl‐2,6‐dinitrobenzenamine] (0.3, 0.6, 1.1 kg/ha) and prodiamine [N3,N3‐Di‐n‐propyl‐2,4‐dinitro‐6‐(trifluoromethyl)‐m‐phenylenediamine] (0.3, 0.6, 1.1 kg/ha). Herbicides were applied in a 0.5‐m band on each bed by using a CO2‐powered backpack sprayer with a single‐nozzle boom delivering 300 L/ha at 172 kPa pressure. The lowest rates of all herbicides did not significantly reduce guayule stand density in 1991 when compared to the control. DCPA at 9.0 kg/ha was adequately selective in both studies. Guayule stand reduction varied from only 2% with DCPA at 4.5 kg/ha in 1991, to 71% with 1.1 kg/ha of pendimethalin in 1992. DCPA (4.5 and 9.0 kg/ha) would be recommended for preemergence weed control, depending on soil type, when direct seeding guayule. Based on row spacing recommendations for transplants, at least three established seedlings/m would be required for an acceptable guayule stand. Seeding rate could be reduced and still allow for effective preemergence weed control.