bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exciton thermal escape in symmetric InAs quantum dots in InGaAs/GaAs well structures
Authors: Casas Espinola J. L. , Torchynska T. V. , Polupan G. , Peña Sierra R. 
Published: February 2007

AbstractThe photoluminescence and its temperature dependence have been investigated for the ensembles of InAs quantum dots embedded in symmetric In0.15Ga0.85As/GaAs quantum wells with different PL intensities. The solution of the set of rate equations for exciton dynamics was used to analyze the nature of thermal activation energies of the QD photoluminescence quenching. It is revealed two different stages of thermally activated quenching of the QD PL intensity caused by thermal escape of excitons from the In0.15Ga0.85As/GaAs QW into the GaAs barrier and from the QDs into the QWs with their subsequent nonradiative recombination. The variety of activation energies of PL thermal quenching is discussed as well. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microwave induced negative resistance states in 2D electron gas with periodic modulation
Authors: Torres Manuel , Kunold Alejandro 
Published: February 2007

AbstractWe study the microwave‐induced photoconductivity of a two‐dimensional electron system (2DES) in the presence of a magnetic field and a two‐dimensional modulation. The microwave and Landau contributions are exactly taken into account, while the periodic potential is treated perturbatively. The longitudinal resistivity exhibits oscillations, periodic in ω /ωc . Negative resistance states (NRS) develop for sufficiently high electron mobility and microwave power. This phenomenon appears in a narrow window region of values of the lattice parameter (a), around a ∼ lB, where lB is the magnetic length. It is proposed that these phenomena may be observed in artificially fabricated arrays of periodic scatterers at the interface of ultraclean heterostructures. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence energy trend for ground and excited states in InAs quantum dots in a well InGaAs/GaAs structures
Authors: Velazquez Lozada E. , Torchynska T. V. , Dybiec M. , Ostapenko S. , Eliseev P. G. , Stintz A. , Malloy K. J. 
Published: February 2007

AbstractThis paper presents the photoluminescence study at 80K and scanning photoluminescence spectroscopy investigation of the ground and multi excited states at 80 and 300K in InAs quantum dots (QDs) inserted in symmetric In0.15Ga0.85As/GaAs QW structures created at different QD growth temperatures. It is shown that some of the structures investigated exhibit a spatial long range variation of the average QD size in the QD ensemble across the sample. This long range QD size inhomogeneity was used for an investigation of the multi excited state energy trend versus ground state energy (or QD sizes). Experimental results were compared with the electron‐hole level energy trend versus QD size predicted theoretically on the base of the 8‐band k·p approach. Some anti correlation between experimental and theoretical results has been revealed and discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photocurrent induced by intersubband transition in a type II and broken‐gap quantum well system
Authors: Wei X. F. , Xu W. , Zeng Z. , Zhang C. 
Published: February 2007

AbstractWe demonstrate theoretically that when an InAs/GaSb based type II and broken‐gap quantum well is subjected to a light field, conductance can be observed along the growth direction due to charge transfer between electron and hole layers. A sharp peak can be observed in conductance within sub‐THz bandwidth. The peak shifts to the lower frequency (red‐shift) with increasing temperature. Our results indicate that InAs/GaSb based quantum well systems are of potential to be applied as sub‐THz photovoltaic devices. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The electronic structure of a Bi/Sb superlattice nanowire
Authors: Zhang G. R. , Zeng Z. 
Published: February 2007

AbstractThe electronic structure of a Bi/Sb superlattice nanowire have been investigated using a theoretical model, in which the nanowire is assumed to possess a circular cross section with a uniform diameter. The variation of the electronic structure as a function of segment length and the total density of states for a Bi/Sb superlattice nanowire with a certain diameter of 5 nm are presented. The minigaps in the total density of states may lead to change in sign of the thermopower for certain energy ranges as the Fermi energy varies, which indicates that the superlattice nanowire can demonstrate n ‐ or p ‐type behavior by using the same dopants. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Neubau der nördlichen Monbijoubrücke über die Spree in Berlin‐Mitte
Authors: Krone Martin , Reinke Klaus‐Dieter 
Published: February 2007

AbstractIm Oktober 2006 wurde nach sechs Jahren Bauzeit das Bodemuseum als nordwestlicher Abschluß der Museumsinsel in Berlin‐Mitte wieder eröffnet. Die Verbindung der Spandauer Vorstadt mit der Museumsinsel über die Spree erfolgt über die nördliche Monbijoubrücke. Für die im Krieg zerstörte zweifeldrige Bogenbrücke war ein Ersatzbauwerk zu errichten, welches in Anlehnung an die historische Brücke als einfeldrige natursteinverkleidete Bogenbrücke ausgeschrieben wurde. Im Zuge der Ausführungsplanung erforderten der gering tragfähige Baugrund am nördlichen Ufer und die Natursteinverblendung des Überbaus eine besonders sorgfältige Planung und Ausführung. Nach 14 Monaten Bauzeit wurde der Neubau am 12. Oktober 2006 rechtzeitig zur Eröffnung des Bodemuseums fertiggestellt.
Characteristics of guindilla (Valenzuela trinervis Bert.) oil
Authors: Aguilera J. M. , Fretes A. , Martin R. San 
Published: February 2007

AbstractSeed of Guindilla (Valenzuela trinervis Bert.) and its oil were characterized. On a dry weight basis, the seed consists of 56% hull and seed coat and 44% cotyledon, containing about 67.0% lipids. The main fatty acids are: 62.3% oleic, 12.9% gadoleic, 10.1% linoleic and 9.6% palmitic. Physical properties of oil, expressed by hand press, include: melting point, −6 to −2 C; iodine value, 75.1; saponification value, 192; and unsaponifiable matter, 0.8%.
Comparative evaluation of polymers of heat‐bodied conjugated and non‐conjugated linseed and soybean oils
Authors: Radlove S. B. , Falkenburg L. B. 
Published: February 2007

SummaryFilms from polymers of heat‐bodied, catalytically conjugated linseed and soybean oils have been shown to be superior, in their resistance to water and dilute alkali solution, to films from polymers of non‐conjugated oils that were heat‐bodies alone and with 0.5% diphenyl disulfide as a polymerization catalyst. These results are not accounted for on the basis of the Scheiber theory of polymerization.
The nondistillation alcohol extraction process for soybean oil
Authors: Beckel A. C. , Belter P. A. , Smith A. K. 
Published: February 2007

SummaryA new vegetable oil extraction process has been developed, with alcohol as the oil solvent. The process requiresno distillation to recover the oil or the solvent characteristics of the alcohol. This has been demonstrated by reuse of the solvent more than 85 times. The theoretical energy requirement of the process is about three‐fourths that of the hexane process.
Destruction of aflatoxins in peanut protein isolates by sodium hypochlorite
Authors: Natarajan K. R. , Rhee K. C. , Cater C. M. , Mattil K. F. 
Published: February 2007

AbstractSodium hypochlorite has been tested for destruction of aflatoxins during the preparation of peanut protein isolates from raw peanuts and defatted peanut meal. The treatments were evaluated by determination of the aflatoxins in the products by thin layer chromatography. Effects of sodium hypochlorite concentration, reaction pH, temperature, and time were studied. Results show that both the sodium hypochlorite concentration and pH are important factors in reducing the concentration of aflatoxins in the protein isolates to nondetectable levels. The treatment with 0.4% sodium hypochlorite at pH 8 produced protein isolates with trace amounts of aflatoxins B1 and B2 from ground raw peanuts containing 725 ppb aflatoxin B1 and 148 ppb aflatoxin B2, whereas untreated protein isolates contained 384 ppb aflatoxin B1 and 76 ppb aflatoxin B2. At pH 9, 0.3% sodium hypochlorite reduced the aflatoxin B1 content in the protein isolates from 300 ppb to below detectable quantities and the aflatoxin B2 content from 52 ppb to 2 ppb. Similar results were obtained at pH 10 for 0.3% sodium hypochlorite concentration. In the case of defatted peanut meal which contained 136 ppb aflatoxin B1 and 36 ppb aflatoxin B2, 0.25% sodium hypochlorite concentration at pH 8 (0.20% at pH 9; 0.15% at pH 10) reduced both the aflatoxin B1 and B2 contents to below detectable quantities in protein isolates as compared to aflatoxin levels of ca. 75 ppb B1 and 17 ppb B2 in the untreated protein isolates. Reaction temperature and time did not affect the destruction of aflatoxins significantly.
Micro vapor‐phase hydrogenation monitored with tandem chromatography‐radioactivity. II. Evaluation of catalyst selectivity for linolenate
Authors: Mounts T. L. , Dutton H. J. 
Published: February 2007

AbstractMicro vapor‐phase hydrogenation is a rapid and effective method of studying the kinetic characteristics of hydrogenation catalysts. Eight catalysts were investigated, and reaction rates and selectivity ratios determined by an analog computer. Fatty esters labeled with C14 were utilized to clarify reactions and to assist in achieving a unique simulation of the data for a particular catalyst.
Automated gradient‐elution column chromatography of lipids
Authors: Nelson Gary J. 
Published: February 2007

AbstractAn automated gradient‐elution chromatography system was developed specifically for the separation of complex mixtures of naturally occuring lipids obtained from various tissues. It uses silica gel columns with concave gradients of increasing polarity. These gradients offer advantages over the convex type because of the absorptive properties of most lipid classes on silica gel.The entire system is operated automatically once the charge is placed on the column. The flow rate is constant throughout the run and the shape of the gradient is predetermined by selecting known values for three parameters. The selection of the gradient is arbitrary but previous knowledge of the chromatographic behavior of the substances to be separated is useful in determining the shape of the gradient. The entire system is controlled by timers, pumps, and solenoid valves. Details of the construction of the apparatus are described and criteria for the selection of acceptable pumps for organic solvents are discussed.Several examples of the separations obtained with the system are described. While silica gel was used as the adsorbent, there is no reason to believe that other adsorbers cannot be substituted for other application. In addition, column size and elution times can be changed to provide better resolution for the specific problems, greatly broadening the application of liquid column chromatography, particularly in the area of routine quantitative analysis of nonvolatile substances. Nongradient elution can also be performed by this apparatus.
The fatty acids of degras
Authors: Pelick Nicholas , Shigley J. W. 
Published: February 2007

AbstractDegras contains a complex mixture of lipids comprised of branched and normal chain fatty acids, hydroxy acids, sterols, sterol esters and long chain wax esters. There are no glycerides in degras. This paper is a report on the composition of the branched and normal chain fatty acids. Preparative techniques of thin‐layer chromatography were used to isolate the fatty acids from the other lipid classes. Gas chromatography was used on three different stationary phase separations of the fatty acid methyl esters. Identifications of the composition were based on a combination of techniques and known standards.
Volatile compounds produced by copper‐catalyzed oxidation of butterfat
Authors: Forss D. A. , Angelini Pio , Bazinet M. L. , Merritt Charles 
Published: February 2007

AbstractAnhydrous butterfat treated with copper and stored under vacuum at 38C in the dark for 9 weeks yielded the C5‐8n‐alkanes, acetic acid and the C4,5,7,9 alkan‐2‐ones. The same butterfat stored under oxygen for 1 week yielded the C1,2,3,5–7n‐alkanes, the C2,4‐6,8 alk‐l‐enes, the C7,8 alk‐l‐ynes, the C2‐6n‐alkanoic acids, ethanol, the C2‐7n‐alkanals, 3‐methylbutanal and 4‐methylpentanal, the C1‐4n‐alkyl formates, ethyl acetate and propionate,n‐propyl acetate and propionate, and butanone. Both treatments yielded carbon dioxide. All samples including those not treated with copper yielded butane‐2,3‐dione.
Seed and seed oil ofPistacia Terebinthus andP. Lentiscus
Authors: Marcopoulos C. A. 
Published: February 2007

AbstractSeeds ofPistacia Terebinthus L. andP. Lentiscus L. were collected from Greek Islands and their composition was determined.Seed oil was taken through various processes and the determination of its physical constants and chemical characteristics was carried out. The maximum and minimum of all the values obtained as well as mean values are given. From iodine and thiocyanogen values the glyceride composition of Pistacia oil was also calculated. Average values are also tabulated.
Reaction of dichlorocarbene with fats and oils
Authors: Kenney H. E. , Komanowsky Daria , Wrigley A. N. 
Published: February 2007

AbstractDichlorocarbene was generated in the presence of lard, olive, safflower, tung and menhaden oil. When solutions of fats or oils in ethyl trichloroacetate were mixed with sodium methoxide inn‐heptane at 2C, unsaturated components were transformed in high conversion to dichlorocyclopropane derivatives; fats were converted to methyl‐and‐ethyl esters (90%) or appeared as glycerides (10%). The proportion of dichlorocyclopropane rings was the same in the glycerides as in the ester products. The reactivity of safflower oil required metered addition of reactants at 25舑55C.Properties were measured on dichlorocyclo‐propanoid fatty esters freed from glycerides but containing saturated esters. Chlorine content ranged from 12舑33%. Compatibility with silicone oils was substantially improved. Viscosities and densities increased with chlorine content. Viscosity indices were 135,150,49,67 and 79 for products from lard, olive, safflower, tung and menhaden oil.Dichlorocarbene could be generated without alcoholysis of glycerides by decomposition of sodium trichloroacetate. This gave dichlorocyclopropanes from safflower oil unsaturates in 50% conversion, but failed with lard.Analyses were performed by TLC, argentation and GLC.
Mustard seed processing: Improved methods for isolating the pungent factor and controlling protein quality
Authors: Mustakas G. C. , Kirk L. D. , Sohns V. E. , Griffin E. L. 
Published: February 2007

AbstractA modified cooking and extraction process for mustard seed is reported in which the pungent factor, allyl isothiocyanate, is separated from the seed to yield triglyceride oil and protein meal. Although removal of the pungent factor from the oil and meal products was previously reported, investigations were continued to develop critical improvements in the process. A reduction in conversion time, combined with steam stripping and shorter heating preiods, resulted in quantitative recovery of the essential oil and in improved protein quality, as measured by the basic amino acids. Biological testing with rats showed the processed meals to be free of toxic and goitrogenic factors and to be well utilized nutritionally. Preliminary estimates indicate that process costs are nearly the same as for a comparable soybean plant.
Cod liver oil fatty acids as secondary reference standards in the GLC of polyunsaturated fatty acids of animal origin: analysis of a dermal oil of the atlantic leatherback turtle
Authors: Ackman R. G. , Burgher R. D. 
Published: February 2007

AbstractThe use of the esters of whole cod liver oil fatty acids as secondary standards in the GLC identification of animal polyunsaturated fatty acids is feasible. This technique is exemplified by an analysis on several polyester substrates of the component fatty acids of a somewhat unusual marine‐type oil from the Atlantic Leatherback turtleDermochelys coriacea coriacea (Linnȳ), with provisional identifications of minor components through the linear log plot and separation factor procedures.
Chromatographically homogeneous lecithin from egg phospholipids
Authors: Singleton W. S. , Gray M. S. , Brown M. L. , White J. L. 
Published: February 2007

AbstractChromatographically homogeneous egg lecithin, as determined by TLC on Silica Gel G, has been isolated from crude egg phosphatides by column chromatography on alumina through modification of existing, lengthy methods. The modified method involved application of crude egg phosphatides to a column of alumina in the proportion of 1 g phosphatide/25 g alumina, and elution of the lecithin fraction with the 2‐component solvent system chloroform:methanol, 9:1 by vol. This method of purification separated lecithin from other choline and non‐choline components of crude phosphatides, avoided overloading of the alumina column, and made unnecessary the need for a second chromatographic fractionation of partially purified lecithin on silicic acid, which is needed in existing methods of purification of lecithin.The use of fresh yolks permitted easier removal of pigment from the final product than was possible with commercially dried yolks.Phosphatides extracted from dried yolks were much more highly colored than were the phosphatides extracted from fresh yolks and the color presisted through chromatography on alumina.The fatty acid/phosphorus molar ratio of the purified lecithin was 2.00, which is the theoretical FA/P molar ratio of phosphatidylcholine; other materials with this ratio were not present.
Positional distribution of fatty acids in the triacylglycerols of developing oil palm fruit
Authors: George S. , Arumughan C. 
Published: February 2007

AbstractThe pattern of accumulation of triacylglycerols, their fatty acid compositions and the positional distribution of the fatty acids at thesn‐2‐ andsn‐1,3‐positions of the triacylglycerol molecules at progressive stages of oil palm fruit development were determined. There was an exponential rate of increase of triacylglycerols and their fatty acids toward the end of fruit development. The fatty acid composition of the triacylglycerols in the early stages of development, prior to active accumulation, was more or less similar, but differed appreciably from the later stages, and the transition of fatty acid composition toward that of normal palm oil occurred at around 16 wk after anthesis (WAA) and stabilized at 20 WAA. All fatty acids increased in terms of absolute quantity. There was an overall consistency in fatty acid positional distribution, irrespective of development stage. More saturated fatty acids were found to be esterified at thesn‐1,3‐positions and more unsaturated fatty acids at thesn‐2‐position of triacylglycerol. Higher rate of incorporation of 16:0 at the 1,3‐positions during the active phase of triacylglycerol synthesis was observed, while 18:1 acid exhibited a reverse trend.
Thermal densturation of glycinin as a function of hydration
Authors: Sessa David J. 
Published: February 2007

AbstractHydration effects on the thermal stability of glycinin (soybean 11S protein) were examined by differential scanning calorimetry (DSC). In a model system with pure glycinin, the denaturation temperature (Td) decreased with increasing moisture. Between 22 and 44% moisture, two endotherms were observed, where the lower‐temperature endotherm became progressively reduced in magnitude with a concomitant increase in a higher‐temperature transition. At 45.5% moisture, only a single endotherm was observed. The regression curves over the entire moisture range from 2 to 66% were derived as asymptote functions, where M equals the percentage total moisture. Equations were developed from the curves, and the relationship between Td and moisture were: Td=92.4+196.5e−0.068M and, for the low‐temperature endotherm, 82.4+144.3e−0.068M. By interaction of 11S protein with either ethanol, a neutral detergent (Triton X‐100) or 40% sucrose, both one‐ and two‐endotherm curves were generated. Such calorimetric behavior is indicative of nonequilibrium denaturation and supports the notion that structure reorganization during DSC is water content‐dependent. Our findings suggest that either glycinin’s acidic/basic subunits or a change in secondary protein structure may give rise to two endotherms.
Apolipoprotein E polymorphism and changes in serum lipids during a family-based counselling intervention
Authors: Salminen Marika , Lehtimäki Terh , Fan Yue-Mei , Vahlberg Tero , Kivelä Sirkka-Liisa 
Published: February 2007

AbstractObjectiveTo compare serum lipids and their changes during a family-based health education in children aged 6–17 years with or without the ɛ4 allele of the gene encoding apolipoprotein E (apoE).DesignAn intervention study.SettingA family-based prevention of risk factors of coronary heart disease in Eastern Finland. The programme consisted of two counselling meetings at children's schools and three at children's homes.SubjectsFour hundred and thirty-nine children with a family history of cardiovascular diseases (CVD) participated in a family-based health education. The children were divided into two groups according toapoEgenotype. The risk group consisted of 143 children havingapoEɛ4 allele (genotype ɛ3/4 or ɛ4/4) and the non-risk group of 296 children withoutapoEɛ4 allele (ɛ2/3 or ɛ3/3). The final sample of the follow-up study included 354 (81%) children (114 and 240, respectively).ResultsBaseline differences were found in low-density lipoprotein cholesterol (LDL-C) (P= 0.007) and LDL-C/high-density lipoprotein cholesterol (HDL-C) ratio (P= 0.030) among boys and in total cholesterol (TC)/HDL-C (P= 0.008) and LDL-C/HDL-C ratios (P= 0.006) among girls. Differences between groups in changes during the follow-up were observed only for TC/HDL-C ratio (P-value adjusted for age = 0.049) among boys.ConclusionsAt baseline, children withapoEɛ4 allele had on average a more unfavourable lipid profile than those withoutapoEɛ4 allele. However, the effect of about 33 months' family-based health education on plasma lipids did not depend onapoEgenotype in children with a family history of CVD.
Early post‐operative morbidity after superficial parotidectomy: a prospective study concerning pain and resumption of normal activity
Authors: Foghsgaard S. , Foghsgaard J. , Homøe P. 
Published: February 2007

Keypoints• The degree of pain and time to return to work following superficial parotidectomy has not previously been reported.• Pain is measured by use of visual analogue scale and the use of analgesics is registered 14 days after superficial parotidectomy.• Results showed that pain is generally weak after superficial parotidectomy and can be treated with mild analgesics. Pain is considerably lower than, e.g. after tonsillectomy.• Median number of days until total recovery was 12 days (range: 3–70), and median time to return to work was 16 days (range: 3–70).• We recommend 2 weeks recreation period after superficial parotidectomy.
Cochlear implant electrode array insertion monitoring with intra‐operative 3D rotational X‐ray
Authors: Carelsen B. , Grolman W. , Tange R. , Streekstra G.J. , Van Kemenade P. , Jansen R.J. , Freling N.J.M. , White M. , Maat B. , Fokkens W.J. 
Published: February 2007

Keypoints• During cochlear implantation surgery, we use a mobile C‐arm with 3D functionality to acquire per‐operative 3D X‐ray images.• Scanning the multielectrode array is performed once before removal of the stylet and once after full insertion.• When dissatisfied with the position of the multielectrode a repositioning is considered which happened occasionally.• The major advantage is the extra certainty of the multielectrode array position in the cochlea with low‐dose and little extra time.• All cochlear implantations are now routinely scanned during surgery.