bluuebunny/crossref_metadata_2025 huggingface dataset:
Short method for the detection of chick edema factor in fats, oils and fatty acids by electron capture gas chromatography
Authors: Kins N. , Barandy J.
Published: April 2007

The electron capture gas liquid chromatography test method for chick edema factor has been modified by replacing the alumina column step with an additional sulfuric acid cleanup and a caustic wash which permits a reduction in sample cleanup time. Samples are subjected to double preliminary sulfuric acid cleanup and caustic wash and extracted each time with trimethyl pentane. The final extract is washed with sulfuric acid and examined by electron capture gas chromatography. Gas chromatographic peaks with retention times vs. Aldrin (Ra values) between 8 and 45 are indicative of the presence of chick edema factor.
A rapid procedure for the determination of residual hexane in oilseed meals and flours
Authors: Fore Sara P. , Dupuy H. P.
Published: April 2007

A rapid and direct gas chromatographic procedure is described for the quantitative determination of residual hexane in finely ground oilseed meals and flours. A 0.04 g sample of meal or flour is added between two small plugs of glass wool in a liner of the injection port of a gas chromatograph. The liner with the sample is placed in the heated injection port and firmly secured, and 80 μl of water is immediately injected just above the glass wool which covers the sample. Volatiles which are rapidly eluted from the sample are then analyzed by temperature‐programmed gas chromatography on a 2 ft × 1/4 in. Porapak P column. The results are comparable to the results obtained by the simple and efficient but more time consuming volatilization procedure. Since results are obtained within 20 min, this rapid procedure is very useful in monitoring desolventization processes.
Homogeneous hydrogenation of methylcis‐9,cis‐15‐octadecadienoate catalyzed by platinum‐tin, palladium and nickel complexes
Authors: Frankel E. N. , Itatani Hiroshi , Bailar John C.
Published: April 2007

Methylcis‐9,cis‐15‐octadecadienoate was used as a model for the hydrogenation of methyl linolenate. Homogeneous catalysis by platinum, palladium and nickel complexes produced a mixture of isomeric monoenes similar to that from the hydrogenation of methyl linolenate. These catalysts are, therefore, capable of promoting isomerization of isolated double bonds and of producing conjugated dienes which are necessary for the formation of monoenes.
Kinetics of the reaction of isopropenyl acetate and stearic acid to form isopropenyl stearate
Authors: Kozempel Michael F. , Craig James C. , Sinnamon Howard I. , Aceto Nicholas C.
Published: April 2007

A mathematical kinetics model has been developed for the reaction of stearic acid with isopropenyl acetate to form isopropenyl stearate. Though the reaction is reversible, the kinetics can be described mathematically most simply by a pseudo first order irreversible reaction model. The model predicts the rate of formation of isopropenyl stearate as a function of time, temperature, catalyst concentration and equilibrium concentration of isopropenyl stearate. Equilibrium is determined from an empirical equation as a function of the ratio of the original concentration of the reactants. Temperature has little effect on the equilibrium.
Detection of aflatoxin using small columns of florisil
Authors: Velasco James
Published: April 2007

This simplified procedure to detect aflatoxin in cottonseed and cottonseed products can be used at the field level where equipment for thin layer chromatography is not available. Contamination levels as low as 10 ppb can be detected in these columns or tubes using longwave uv light. Development and detection of aflatoxin in these tubes takes ca. 10 min.
Control of pollutants for the oilseeds industry
Authors: Becker Kenneth W.
Published: April 2007

To stay in business the oilseeds industry must comply with EPA and other regulations established by governing bodies. We must expect “ecology” to be the prime national concern for this decade. Hence ecological regulations will be sternly enforced. Causes of water and air pollution should be thoroughly investigated. The probable effects of uncontrolled pollution—severe penalties, product losses, hazards to community—are generally known. Fundamental commitments for pollution abatement must be made by governing bodies, operating company top managements, engineering firms and equipment manufacturers. Existing technology coupled with rigid engineering design will permit us to meet most of today’s pollution abatement needs. However to meet tomorrow’s ecological needs the oilseeds industry and engineering firms serving it must make technological breakthroughs and upgrade the quality of their engineering. Pollution remedies should be a major concern collectively by this technical society, operating companies and engineering firms.
Contact angle studies on viable human skin: II. Effect of surfactant ionic type in pretreatment
Authors: Ginn M. E. , Dunn Suzanne C. , Jungermann Eric
Published: April 2007

The effect of presoaking with various surfactant solutions on the skin‐water contact angle was investigated. Various cationic surfactants and amine oxides were found to lower the skinwater contact angle at lowest concentrations. Rinsability data supported the findings and suggested that cationic surfactants are tightly bound to the skin.
Thin layer and anion exchange chromatography of soybean saponins
Authors: Wolf W. J. , Thomas Betty W.
Published: April 2007

Twenty‐two solvent systems were evaluated for TLC of soybean saponins on silica gel. A maximum of four fractions separated by single development with the different solvents. Six successive developments with chloroformmethanol‐water (65:25:4) separated soybean saponins into 10 or more fractions. Column chromatography of soybean saponins on an anion exchange resin with a linear gradient of acetic acid yielded seven fractions. Multiple development TLC of the saponins separated by column chromatography showed that a definite fractionation occurred. Several column chromatographic fractions contained components with identical TLC Rf values, but the components were clearly different on the basis of colors detected with sulfuric acid and on the basis of their elution positions from the ion exchange resin. Soybean saponins are more complex mixtures than previously recognized but can be fractionated by chromatography on thin layer plates and anion exchange resins.
Pretreating delintered cottonseed to increase yield of whole kernels
Authors: Lawhon J. T.
Published: April 2007

Pretreatment of delintered glandless seed before decortication by (a) heating seed containing different kernel moistures with live steam followed by drying with indirect heat, (b) heating seed containing different kernel moistures with live steam followed by rapid cooling with air, (c) heating seed containing different kernel moistures with superheated steam followed by drying with indirect heat, and (d) heating seed containing different kernel moistures with super‐heated steam followed by rapid cooling with air to ambient temperatures, was investigated. Also reported are analytical data which allow an assessment of any changes in protein quality resulting from the treatments applied and data from organoleptic evaluations of treated and untreated glandless cottonseed kernels prepared as high‐protein edible nuts.
Carotenoids and tocols of corn grain determined by HPLC
Authors: Weber Evelyn J.
Published: April 2007

A high performance liquid chromatographic (HPLC) procedure has been developed that permits determinationof carotenoids and tocols in the same sample preparation of corn grain. For 15 inbreds, the total carotenoids ranged from 16 to 77 µg/g dry wt and the total tocols from 30 to 128 µg/g dry wt. For four inbreds, total carotenoids were concentrated in the horny endosperm (83±2%) and total tocols in the germ (77±6%). After six months storage at room temperature, the mean loss of total carotenoids for four inbreds was 42±4%, while the tocols had a mean loss of 5%.
Synthesis of 18‐octadecanolide, a major constituent of dufour's gland secretion ofColletes bees
Authors: Gangadhar A. , Subbarao R. , Lakshminarayana G.
Published: April 2007

18‐Octadecanolide, a major constituent of Dufour's gland secretion ofColletes bees, was synthesized by polymerization followed by depolymerization of 18‐hydroxyoctadecanoic acid which in turn was obtained by hydrogenation of kamlolenic acid (18‐hydroxy, 9‐cis, 11‐trans, 13‐trans‐octadecatrienoic acid) isolated fromMallotus philippinensis seed oil. The structures of the intermediates as well as the final lactone were established by infrared, proton nuclear magnetic resonance and mass spectrometric methods.
Octadecatrienoic fatty acid isomers of partially hydrogenated soybean oil
Authors: Perkins E. G. , Smick Cathysue
Published: April 2007

The octadecatrienoic fatty acids of partially hydrogenated soybean oil (PHSBO) were concentrated, isolated and analyzed. The results indicated that the 18:3 acids present in PHSBO are composed of four isomers. The isomer present in the largest amount (2.7%) is the allcis isomer, c9,c12,c15‐18:3 linolenic acid, and comprises 68.60% of all the isomeric 18:3 acids of PHSBO.

The remaining three 18:3 isomers found were t9,t12,c15‐,t9,c12,c15‐and c9,c12,t15‐18:3, which in total accounted for 1.2% of the total fatty acids of PHSBO.
Adsorption of lutein from soybean oil on silicic acid I. Isotherms
Authors: Proctor Andrew , Snyder Harry E.
Published: April 2007

Adsorption of lutein from crude soybean oil miscella on dispersed silicic acid resulted in three different Freundlich type isotherms, depending on the amount of adsorbent used. Normally, changing the amount of adsorbent gives a new point on the same isotherm. Further investigation of the lutein adsorption revealed that addition of 1% isopropanol to the hexane solvent and deactivation of the silica acid with water decreased lutein adsorption. Purification of the lutein resulted in increased adsorption, indicating that triglyceride was competing for adsorption sites. The triglyceride competition was confirmed by calculating an adsorption isotherm for triglyceride from crude soybean oil miscella. Use of silicic acid as a column rather than dispersed yielded multiple isotherms for lutein adsorption based on the amount of adsorbent used. Also, lutein adsorption on columns was concentrated at the entrance to the column. Experiments showed that lutein adsorption was not due to partitioning between bound triglyceride and hexane solvent.
Cholesterol metabolism in swine fed diets containing either casein or soybean protein
Authors: Beynen A. C. , West C. E.
Published: April 2007

Diets containing casein produce higher concentrations of serum cholesterol in swine than those containing soybean protein, but only when such diets contain high levels of cholesterol. We suggest that dietary casein causes an increase in the absorption of cholesterol and bile acids, thus explaining the observed decrease in fecal excretion of neutral steroids and bile acids when compared to soybean protein. The mechanism in molecular terms by which dietary proteins influence steroid absorption remains to be established.
Serum lipoproteins of rabbits fed semi‐purified diets varying in protein and carbohydrate source
Authors: Bauer John E.
Published: April 2007

The effect of dietary protein and carbohydrate type on the composition and properties of serum lipoproteins in rabbits was studied. The animals were pair‐fed either casein‐sucrose and soy protein‐sucrose or casein‐dextrose and soy protein‐dextrose‐containing low fat, low cholesterol, semi‐purified diets for 84 days. Main effects due to protein and carbohydrate type were observed to be altered lipoprotein class compositions. These effects were due primarily to the presence of casein which resulted in cholesterol‐rich, triglyceride‐poor lipoproteins among all isolated classes. Increases in serum low and high density lipoprotein cholesterol and protein concentrations, as well as lipoprotein total mass, were also observed with casein feeding. Carbohydrate effects due to dietary sucrose were elevated high density lipoprotein phospholipid and protein concentrations, independent of protein source. When casein was included, sucrose‐containing diets resulted in increased intermediate density lipoprotein cholesterol; when soy protein was used, low density lipoprotein cholesterol elevations were observed. Dietary interactions were also found especially between casein and sucrose, resulting in increased intermediate lipoprotein mass and total lipoprotein concentrations. Comparisons of lipoprotein class particle size among rabbits indicated similar particle diameters among animals in all dietary groups. Evidence that casein feeding caused increased lipoprotein particle number in addition to compositional differences was obtained. It was concluded that lipoprotein structure within a given class is maintained in spite of compositional variations due to dietary protein or carbohydrate source.
Susceptibility of types of peanuts to rancidity development
Authors: Pickett T. A. , Holley K. T.
Published: April 2007

Conclusions

Based on the data from over 70 trials involving peanuts grown during six consecutive seasons, oil from Spanish peanuts is more susceptible to peroxide rancidity development than that from either the Runner or Virginia types.
Systemic Inflammation and Repair of Abdominal Aortic Aneurysm
Authors: Tambyraja Andrew L. , Dawson Raymond , Valenti Domenico , Murie John A. , Chalmers Roderick T.
Published: April 2007

Background

Inflammation is integral to the pathogenesis of abdominal aortic aneurysm (AAA). This study examines preoperative biomarkers of systemic inflammation in patients undergoing open repair of intact and ruptured AAA.

Methods

One‐hundred twelve patients were entered into a prospective observational study. Preoperative POSSUM physiology score, C‐reactive protein (CRP), white blood count (WBC), platelet count, fibrinogen, and albumin were recorded and related to clinical variables using univariate analysis.

Results

Sixty‐one patients with a ruptured AAA, 39 with an asymptomatic intact AAA, and 12 with an acutely symptomatic intact AAA underwent attempted repair. There were two inflammatory asymptomatic aneurysms and one inflammatory ruptured aneurysm. No patient had clinical evidence of coexistent inflammatory disease. Patients with a symptomatic intact AAA had a significantly greater level of CRP and fibrinogen, higher WBC, and lower serum albumin, than those with an asymptomatic intact AAA. Patients with a ruptured aneurysm had a significantly greater level of CRP, higher WBC, and lower serum albumin than those with an asymptomatic intact aneurysm. Patients with a symptomatic intact AAA had a significantly higher CRP level, but lower WBC, than those with a ruptured AAA. There was no difference in CRP level, WBC, or serum albumin between survivors and non‐survivors of attempted repair of asymptomatic, symptomatic and ruptured AAA.

Conclusions

Acutely symptomatic and ruptured AAAs are associated with an early elevation in systemic inflammatory biomarkers. This early activation of the inflammatory response might influence perioperative outcome.
Identification and Characterization of a Novel Bovine Stearoyl‐CoA Desaturase Isoform with Homology to Human SCD5
Authors: Lengi Andrea J. , Corl Benjamin A.
Published: April 2007

Stearoyl‐CoA desaturase (SCD) is an enzyme responsible for the production of cis‐9, trans‐11 conjugated linoleic acid in ruminant fats, and for the synthesis of palmitoleoyl‐CoA and oleoyl‐CoA. To date, only one SCD isoform has been described in ruminant species, although multiple isoforms have been found in many other mammalian species. In this paper, we describe for the first time a second SCD isoform in cattle, which appears to be an ortholog of human SCD5 rather than a homolog of bovine SCD1 or any of the described murine SCD isoforms. As described in other SCD proteins, the predicted amino acid sequence of bovine SCD5 includes four transmembrane domains and three conserved histidine motifs. The amino‐terminus of the predicted protein sequence of SCD5 lacks the PEST sequences typically found in SCD1 homologs, which are thought to target proteins for rapid degradation. Similar to human SCD5, the bovine SCD5 gene is organized into five exons and four introns, and is highly expressed in the brain. In other tissues examined, mRNA expression of SCD5 was minimal. Furthermore, the expression levels of SCD5 between brain gray and white matter are not different. This is the first description of a homolog of human SCD5 in a non‐primate species.
Functionalization of Oleyl Carbonate by Epoxidation
Authors: Kenar James A.
Published: April 2007

Carbonates (esters of carbonic acid H2CO3) are a class of compounds that are of increasing interest in commercial applications due to their physical properties and relatively straightforward synthesis. Herein, oleyl carbonate, an oleochemical‐based compound derived from oleyl alcohol, was epoxidized utilizing performic acid generated in situ from formic acid and 50% H2O2. The reaction proceeded smoothly and furnished the corresponding oleyl carbonate bisepoxide, (bis[8‐(3‐octyloxiran‐2‐yl)octyl] carbonate), in good yields (83–85% isolated yields after purification by silica gel chromatography). The carbonate moiety was found stable to the reaction conditions utilized for epoxidation and the isolated oleyl carbonate bisepoxide was subsequently characterized using Fourier transform infrared spectroscopy, 1H and 13C nuclear magnetic resonance spectroscopy (NMR), and liquid chromatography electrospray ionization mass spectrometry. Oleyl carbonate bisepoxide compound may be of potential interest as a plasticizer, monomer, or a substance for further chemical elaboration.
Familiäre Leukämien
Authors: Fonatsch C. , Wimmer K.
Published: April 2007

Im Gefolge einer Vielzahl von genetisch bedingten Erkrankungen, wie den DNA-Reparatur-Defizienz-Syndromen, Tumordispositions-, Immundefizienz-, Cancer-Family- und Bone-Marrow-Failure-Syndromen sowie bei einigen angeborenen Chromosomenanomalien werden oft Leukämien und andere hämatologische Neoplasien beobachtet. In letzter Zeit konnten darüber hinaus in Familien mit erhöhter Leukämieinzidenz konstitutionelle Mutationen spezifischer Gene identifiziert werden, die auch bei sporadischen Leukämien in Form von somatischen Mutationen involviert sind. Neben diesen Mutationen mit hoher Penetranz scheinen Genveränderungen mit niedriger Penetranz oder auch Polymorphismen von Genen, die bei der Zellproliferation, der DNA-Reparatur, der Apoptose, der Detoxifizierung u. a. m. eine Rolle spielen, die Disposition zur Leukämieentwicklung bzw. den Krankheitsverlauf zu beeinflussen. Diese neuen Erkenntnisse über konstitutionelle, zu Leukämien disponierende genetische Veränderungen könnten die Kluft zwischen angeborenen und erworbenen genetischen Erkrankungen allmählich überbrücken.
Differential membrane perturbation caused by the cell penetrating peptide Tp10 depending on attached cargo
Authors: Bárány-Wallje Elsa , Gaur Jugnu , Lundberg Pontus , Langel Ülo , Gräslund Astrid
Published: April 2007

The membrane leakage caused by the cell penetrating peptide Tp10, a variant of transportan, was studied in large unilamellar vesicles with the entrapped fluorophore calcein. The vesicles were composed of zwitterionic 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine. A significant decrease in membrane leakage was found when the 55 kDa streptavidin protein was attached to Tp10. When a 5.4 kDa peptide nucleic acid molecule was attached, the membrane leakage was comparable to that caused by Tp10 alone. The results suggest that direct membrane effects may cause membrane translocation of Tp10 alone and of smaller complexes, whereas these effects do not contribute for larger cargoes.
Nitrate transporters and peptide transporters
Authors: Tsay Yi-Fang , Chiu Chi-Chou , Tsai Chyn-Bey , Ho Cheng-Hsun , Hsu Po-Kai
Published: April 2007

In higher plants, two types of nitrate transporters, NRT1 and NRT2, have been identified. In Arabidopsis, there are 53 NRT1 genes and 7 NRT2 genes. NRT2 are high‐affinity nitrate transporters, while most members of the NRT1 family are low‐affinity nitrate transporters. The exception is CHL1 (AtNRT1.1), which is a dual‐affinity nitrate transporter, its mode of action being switched by phosphorylation and dephosphorylation of threonine 101. Two of the NRT1 genes, CHL1 and AtNRT1.2, and two of the NRT2 genes, AtNRT2.1 and AtNRT2.2, are known to be involved in nitrate uptake. In addition, AtNRT1.4 is required for petiole nitrate storage. On the other hand, some members of the NRT1 family are dipeptide transporters, called PTRs, which transport a broad spectrum of di/tripeptides. In barley, HvPTR1, expressed in the plasma membrane of scutellar epithelial cells, is involved in mobilizing peptides, produced by hydrolysis of endosperm storage protein, to the developing embryo. In higher plants, there is another family of peptide transporters, called oligopeptide transporters (OPTs), which transport tetra/pentapeptides. In addition, some OPTs transport GSH, GSSH, GSH conjugates, phytochelatins, and metals.
The lipid peroxidation end‐product 4‐HNE induces COX‐2 expression through p38MAPK activation in 3T3‐L1 adipose cell
Authors: Zarrouki B. , Soares A.F. , Guichardant M. , Lagarde M. , Géloën A.
Published: April 2007

Our results show that oxidative stress induces COX‐2 expression through the production of 4‐HNE which activates p38MAPKinase, suggesting that 4‐HNE links oxidative stress and chronic inflammation through the activation of cyclooxygenase.
Dynamics of Islam, identity, and institutional rule in Uzbekistan: Constructing a paradigm for conflict resolution
Authors: Hanks Reuel R.
Published: April 2007

The “re-Islamization” of society in independent Uzbekistan has proven to be a complex process, generating conflict in the social, cultural and political spheres. Since the early 1990s, the regime of Islam Karimov has sought to undermine any manifestation of “unofficial” Islam via imprisonment of the leadership, implementation of repressive statutes governing religious activity, and other coercive means. Yet, since 1999 Uzbekistan has experienced more religious violence directed against government power structures by “extremists” than any other former Soviet republic in Central Asia. Important issues that should direct U.S. policy remain unresolved: How significant is the threat from radical Islam in Uzbekistan, that is, what are the chances of politicized, “fundamentalist” Islam emerging as a mass movement there? Has recent U.S. policy reduced or exacerbated the dynamics of conflict between the regime and the “radicals?” In order to effect resolution of this conflict, a new paradigm must be implemented in U.S.–Uzbek relations which moves the Uzbek regime toward democratization, while maintaining social stability. In addition, politicized Islam, in a non-radicalized form, should also figure into any policy strategy directed at long-term stability in Uzbekistan.
Melt‐mantle interactions beneath the Kamchatka arc: Evidence from ultramafic xenoliths from Shiveluch volcano
Authors: Bryant J. A. , Yogodzinski G. M. , Churikova T. G.
Published: April 2007

Ultramafic xenoliths of spinel dunite, harzburgite, lherzolite, amphibole/phlogopite‐bearing pyroxenite, and clinopyroxenite occur in andesitic pyroclastic debris from the 1964 eruption of Shiveluch volcano, Kamchatka. Peridotites have coarse/protogranular, porphyroclastic, and granuloblastic textures, abundant kink‐banded olivine, and refractory mineral compositions with forsteritic olivine (Fo88–94) and Cr‐rich spinel (100*Cr/Cr + Al = 47–83). Orthopyroxene (opx) is also Mg‐rich but occurs only as a fibrous mineral present along olivine grain boundaries, in monomineralic veins that crosscut coarse olivine, and in veins with amphibole and phlogopite that crosscut coarse‐grained peridotites. Textural evidence and mineral compositions indicate that the peridotites and hydrous pyroxenites were replacive dunites that formed by melt‐rock reactions involving the dissolution of pyroxene and precipitation of olivine. The fibrous opx and millimeter‐scale veins of phlogopite, amphibole, and opx are interpreted as the autometasomatic products of hydrous magmas that were trapped in the uppermost mantle (<45 km). In this interpretation, opx was produced by reaction between late‐stage, silica‐rich, hydrous fluids/melts and olivine in the dunite protolith, and the millimeter‐scale veins of phlogopite, amphibole, and opx are the volatile‐enriched, deuteric products that were liberated during the final stages of magma crystallization. The absence of textural equilibrium suggests that the late‐stage replacement process which produced the fibrous opx occurred shortly prior to the eruption that carried the xenoliths to the surface. On the basis of two‐pyroxene thermometry and Ca‐in‐olivine barometry, the xenoliths equilibrated between 800 and 1000°C and 1.03 and 2.21 GPa. This implies that the xenoliths were carried from sub‐Moho depths, a result consistent with geophysical estimates of crustal thickness. Olivine‐opx‐spinel equilibria indicate that the xenoliths are strongly oxidized with fO2 from +1.4–2.6 log units above the fayalite‐magnetite‐quartz (ΔFMQ) buffer in peridotites, +1.7–2.3 ΔFMQ in hydrous pyroxenites, and +2.4–3.3 ΔFMQ in cumulate clinopyroxenites. High fO2 in the peridotites is attributed to the melt‐rock reactions that formed the dunite protolith. These results therefore suggest that interaction between oxidized melts and peridotite wall rock at shallow mantle depths plays a significant role in creating and modifying the uppermost mantle and deepest crust in some subduction settings.
Lead (Pb) in old Antarctic ice: Some from dust, some from other sources
Authors: Hinkley Todd
Published: April 2007

Recently published data on amounts and isotopic compositions of lead (Pb) and on amounts of mineral dust in pre‐industrial Antarctic ice can be further interpreted by means of simple calculations. These show that two distinct types of Pb were provided by the atmosphere to the continent in varying proportions during Pleistocene and Holocene time. One type of Pb is that contained in the mineral lattices of dust. It has non‐radiogenic isotopic proportions. The other type of Pb is not associated with dust minerals, is more radiogenic, and is consistent with an origin in emissions from ocean island volcanoes worldwide, or from some Antarctic volcanoes.
Recovery of streamlines in the flank low‐latitude boundary layer
Authors: Hasegawa Hiroshi , Sonnerup Bengt U. Ö. , Fujimoto Masaki , Saito Yoshifumi , Mukai Toshifumi
Published: April 2007

We present first results of a novel technique for producing a two‐dimensional (2‐D) map of the velocity field from single‐spacecraft observations of the bulk plasma parameters and magnetic field. For flow transverse to a unidirectional magnetic field, the MHD equations of motion can be reduced to a Grad‐Shafranov‐type (GS‐type) equation for the stream function (Sonnerup et al., 2006), provided that the plasma structure is 2‐D and time‐independent when seen in its proper frame. We show how this equation can be used to recover the flow field in regions surrounding a spacecraft path, as was first done in the GS reconstruction of the magnetic field by Sonnerup and Guo (1996). The new method is benchmarked by use of an exact solution of the GS‐type equation and further by use of synthetic data from 2‐D MHD simulations of the Kelvin‐Helmholtz instability (KHI). Streamline maps of reasonable accuracy can be generated even when temporal evolution during the KHI development expected at the flank magnetopause is present. Application of the technique to a Geotail encounter with a train of KH waves in the low‐latitude flank boundary layer indicates that a chain of vortices (each of size ∼3 RE by 1 RE) existed and moved tailward along the magnetopause.
Particle‐in‐cell simulation of Maxwellian ring velocity distribution
Authors: Umeda Takayuki , Ashour‐Abdalla Maha , Schriver David , Richard Robert L. , Coroniti Ferdinand V.
Published: April 2007

Electrostatic electron cyclotron harmonic (ECH) and electromagnetic whistler wave emissions are sometimes observed simultaneously in the near‐Earth nightside equatorial magnetotail region. The excitation mechanism for these two wave emissions, however, is quite different with ECH waves excited by a positive slope in the velocity distribution function perpendicular to the ambient magnetic field (such as due to a loss cone or ring velocity distribution), while whistler waves are excited by a temperature anisotropy whereby the perpendicular temperature is larger than the parallel temperature. Here we examine, using a two‐dimensional electromagnetic particle‐in‐cell computer simulation, the excitation of both waves as a consequence of a warm electron ring distribution in the presence of cold background electrons. Initially, ECH waves are excited by the ring distribution in the linear stage, which results in heating of the cold electrons and smearing of the ring distribution. During a nonlinear consequence of the ECH excitation and ensuing electron wave‐particle interactions, whistler waves are also excited by the different instability. Thus both waves are excited during the same simulation run, which may account for the magnetospheric observations of both ECH and whistler waves at the same location where electron loss cone distributions form in the equatorial magnetotail at about 6–9 RE from the Earth.
Summer landfast sea ice desalination at Point Barrow, Alaska: Modeling and observations
Authors: Vancoppenolle Martin , Bitz Cecilia M. , Fichefet Thierry
Published: April 2007

Landfast sea ice cores from two sites in Point Barrow, Alaska, extracted between 1999 and 2001, show a progressive desalination and a corresponding shape transition in the salinity profile starting at snowmelt onset, around 1 June. The vertical percolation of fresh surface meltwater through the permeable ice matrix (flushing) has long been supposed to control this transition. A parameterization of flushing in bare ice is formulated. It is incorporated into the semiempirical winter sea ice desalination model of Cox and Weeks (1988), coupled to the one‐dimensional thermodynamic sea ice model of Bitz and Lipscomb (1999) and forced under Point Barrow conditions. Adjustment to the original Cox and Weeks parameterization of gravity drainage was necessary to give reasonable agreement with observations in winter. With this change the model has the potential to simulate the full seasonal cycle of the Arctic salinity and mass balance of typical Arctic ice. In summer, the model salinity profile closely follows the observations. The model upper ice temperatures are slightly too cold. At the thin snow (Chukchi Sea) site, the model simulates the observed snow depth and ice thickness well. At the thick snow (Elson Lagoon) site, the snow disappears 7 days earlier than observed, which results in underestimating ice thickness. Sensitivity experiments suggest that a more realistic representation of snow and meltwater physics would significantly improve the simulation. Because of the effects of brine drainage on the sea ice mass balance and oceanic circulation, including the time dependence of the ice salinity profile would significantly improve the next generation of sea ice models.
Global sea‐salt modeling: Results and validation against multicampaign shipboard measurements
Authors: Witek Marcin L. , Flatau Piotr J. , Quinn Patricia K. , Westphal Douglas L.
Published: April 2007

Open‐ocean measurements of sea‐salt concentrations from five different campaigns are used to validate the sea‐salt parameterization in numerical models. The data set is unique in that it is from open‐ocean shipboard measurements which alleviates typical problems associated with onshore wave breaking on land stations (surf zone). The validity of the sea‐salt parameterizations is tested by employing a global forecasting model and transport model with detailed representation of dry and wet deposition, advection and diffusion, and other physical processes. It is shown that the inclusion of these processes leads to good agreement with shipboard measurements. The correlation coefficient of measured and modeled sea‐salt mass concentrations for all data points was 0.76 and varied from 0.55 to 0.84 for different experiments. Average sea‐salt mass concentration was 4.6μg/m3 from measurements and 7.3 μg/m3 from the model, for all considered experiments. It was found that model‐measurements discrepancies were affected by wet deposition uncertainties but also suggested was the influence of source uncertainties in the strong wind‐speed regime, lack of a wind‐speed threshold for emission onset, and lack of size differentiation in applied deposition velocity. No apparent relationship between the water temperature and the measured sea‐salt concentration was found in the analyzed data set.
A wetland hydrology and water quality model incorporating surface water/groundwater interactions
Authors: Kazezyılmaz‐Alhan Cevza Melek , Medina Miguel A. , Richardson Curtis J.
Published: April 2007

In the last two decades the beneficial aspects of constructed treatment wetlands have been studied extensively. However, the importance of restored wetlands as a best management practice to improve the water quality of storm water runoff has only recently been appreciated. Furthermore, investigating surface water/groundwater interactions within wetlands is now acknowledged to be essential in order to better understand the effect of wetland hydrology on water quality. In this study, the development of a general comprehensive wetland model Wetland Solute Transport Dynamics (WETSAND) that has both surface flow and solute transport components is presented. The model incorporates surface water/groundwater interactions and accounts for upstream contributions from urbanized areas. The effect of restored wetlands on storm water runoff is also investigated by routing the overland flow through the wetland area, collecting the runoff within the stream, and transporting it to the receiving water using diffusion wave routing techniques. The computed velocity profiles are subsequently used to obtain water quality concentration distributions in wetland areas. The water quality component solves the advection‐dispersion equation for several nitrogen and phosphorus constituents, and it also incorporates the surface water/groundwater interactions by including the incoming/outgoing mass due to the groundwater recharge/discharge. In addition, output from the Storm Water Management Model (SWMM5) is incorporated into this conceptual wetland model to simulate the runoff quantity and quality flowing into a wetland area from upstream urban sources. Additionally, the model can simulate a water control structure using storage routing principles and known stage‐discharge spillway relationships.
Traffic restrictions associated with the Sino‐African summit: Reductions of NOx detected from space
Authors: Wang Yuxuan , McElroy Michael B. , Boersma K. Folkert , Eskes Henk J. , Veefkind J. Pepijn
Published: April 2007

Aggressive measures were instituted by the Beijing municipal authorities to restrict vehicular traffic in the Chinese capital during the recent Sino‐African Summit. We show that reductions in associated emissions of NOx were detected by the Dutch‐Finnish Ozone Monitoring Instrument (OMI) aboard the Aura satellite. Interpretation of these data using a 3‐dimensional chemical transport model indicates that emissions of NOx were reduced by 40% over the period of November 4 to 6, 2006, for which the restrictions were in place.
DNA damage induces Chk1‐dependent centrosome amplification
Authors: Bourke Emer , Dodson Helen , Merdes Andreas , Cuffe Lorraine , Zachos George , Walker Mark , Gillespie David , Morrison Ciaran G
Published: April 2007

Centrosomal abnormalities are frequently observed in cancers and in cells with defective DNA repair. Here, we used light and electron microscopy to show that DNA damage induces centrosome amplification, not fragmentation, in human cells. Caffeine abrogated this amplification in both ATM (ataxia telangiectasia, mutated)‐ and ATR (ATM and Rad3‐related)‐defective cells, indicating a complementary role for these DNA‐damage‐responsive kinases in promoting centrosome amplification. Inhibition of checkpoint kinase 1 (Chk1) by RNA‐mediated interference or drug treatment suppressed DNA‐damage‐induced centrosome amplification. Radiation‐induced centrosome amplification was abrogated in Chk1−/− DT40 cells, but occurred at normal levels in Chk1−/− cells transgenically expressing Chk1. Expression of kinase‐dead Chk1, or Chk1S345A, through which the phosphatidylinositol‐3‐kinase cannot signal, failed to restore centrosome amplification, showing that signalling to Chk1 and Chk1 catalytic activity are necessary to promote centrosome overduplication after DNA damage.
The major determinant of the heparin binding of glial cell-line-derived neurotrophic factor is near the N-terminus and is dispensable for receptor binding
Authors: Alfano Ivan , Vora Parvez , Mummery Rosemary S. , Mulloy Barbara , Rider Christopher C.
Published: April 2007

GDNF (glial cell-line-derived neurotrophic factor), and the closely related cytokines artemin and neurturin, bind strongly to heparin. Deletion of a basic amino-acid-rich sequence of 16 residues N-terminal to the first cysteine of the transforming growth factor β domain of GDNF results in a marked reduction in heparin binding, whereas removal of a neighbouring sequence, and replacement of pairs of other basic residues with alanine had no effect. The heparin-binding sequence is quite distinct from the binding site for the high affinity GDNF polypeptide receptor, GFRα1 (GDNF family receptor α1), and heparin-bound GDNF is able to bind GFRα1 simultaneously. The heparin-binding sequence of GDNF is dispensable both for GFRα1 binding, and for activity for in vitro neurite outgrowth assay. Surprisingly, the observed inhibition of GDNF bioactivity with the wild-type protein in this assay was still found with the deletion mutant lacking the heparin-binding sequence. Heparin neither inhibits nor potentiates GDNF–GFRα1 interaction, and the extracellular domain of GFRα1 does not bind to heparin itself, precluding heparin cross-bridging of cytokine and receptor polypeptides. The role of heparin and heparan sulfate in GDNF signalling remains unclear, but the present study indicates that it does not occur in the first step of the pathway, namely GDNF–GFRα1 engagement.
Sirtuins in mammals: insights into their biological function
Authors: Michan Shaday , Sinclair David
Published: April 2007

Sirtuins are a conserved family of proteins found in all domains of life. The first known sirtuin, Sir2 (silent information regulator 2) of Saccharomyces cerevisiae, from which the family derives its name, regulates ribosomal DNA recombination, gene silencing, DNA repair, chromosomal stability and longevity. Sir2 homologues also modulate lifespan in worms and flies, and may underlie the beneficial effects of caloric restriction, the only regimen that slows aging and extends lifespan of most classes of organism, including mammals. Sirtuins have gained considerable attention for their impact on mammalian physiology, since they may provide novel targets for treating diseases associated with aging and perhaps extend human lifespan. In this review we describe our current understanding of the biological function of the seven mammalian sirtuins, SIRT1–7, and we will also discuss their potential as mediators of caloric restriction and as pharmacological targets to delay and treat human age-related diseases.
Co-operative Cdc42 and Rho signalling mediates ephrinB-triggered endothelial cell retraction
Authors: Groeger Gillian , Nobes Catherine D.
Published: April 2007

Cell repulsion responses to Eph receptor activation are linked to rapid actin cytoskeletal reorganizations, which in turn are partially mediated by Rho–ROCK (Rho kinase) signalling, driving actomyosin contractility. In the present study, we show that Rho alone is not sufficient for this repulsion response. Rather, Cdc42 (cell division cycle 42) and its effector MRCK (myotonic dystrophy kinase-related Cdc42-binding kinase) are also critical for ephrinB-induced cell retraction. Stimulation of endothelial cells with ephrinB2 triggers rapid, but transient, cell retraction. We show that, although membrane retraction is fully blocked by blebbistatin (a myosin-II ATPase inhibitor), it is only partially blocked by inhibiting Rho–ROCK signalling, suggesting that there is ROCK-independent signalling to actomyosin contractility downstream of EphBs. We find that a combination of either Cdc42 or MRCK inhibition with ROCK inhibition completely abolishes the repulsion response. Additionally, endocytosis of ephrin–Eph complexes is not required for initial cell retraction, but is essential for subsequent Rac-mediated re-spreading of cells. Our data reveal a complex interplay of Rho, Rac and Cdc42 in the process of EphB-mediated cell retraction–recovery responses.
Absence of ferromagnetism in V-implanted ZnO single crystals
Authors: Zhou Shengqiang , Potzger K. , Reuther H. , Kuepper K. , Skorupa W. , Helm M. , Fassbender J.
Published: April 2007

The structural and magnetic properties of V doped ZnO are presented. V ions were introduced into hydrothermal ZnO single crystals by ion implantation with fluences of 1.2×1016–6×1016cm−2. Postimplantation annealing was performed in high vacuum from 823to1023K. The ZnO host material still partly remains in a crystalline state after irradiation and is partly recovered by annealing. The V ions show a thermal mobility as revealed by depth profile Auger electron spectroscopy. Synchrotron radiation x-ray diffraction revealed no secondary phase formation which indicates the substitution of V onto Zn site. However, in all samples no pronounced ferromagnetism was observed down to 5K by a superconducting quantum interference device magnetometer.
Reversible susceptibility studies of magnetization switching in FeCoB synthetic antiferromagnets
Authors: Radu Cosmin , Cimpoesu Dorin , Girt Erol , Ju Ganping , Stancu Alexandru , Spinu Leonard
Published: April 2007

In this paper we present a study of switching characteristics of a series of synthetic antiferromagnet (SAF) structures using reversible susceptibility experiments. Three series of SAF samples were considered in our study with (t1, t2), the thickness of the FeCoB layers of (80nm, 80nm), (50nm, 50nm), and (80nm, 20nm) and with the interlayer of Ru ranging from 0to2nm. A vector vibrating sample magnetometer was used to measure the hysteresis loops along the different directions in the plane of the samples. The reversible susceptibility experiments were performed using a resonant method based on a tunnel diode oscillator. We showed that the switching peaks in the susceptibility versus field plots obtained for different orientations of the applied dc field can be used to construct the switching diagram of the SAF structure. The critical curve constitutes the fingerprint of the switching behavior and provides information about micromagnetic and structural properties of SAF which is an essential component of modern magnetic random access memories.
Equivalence of energy methods in stability theory
Authors: Birtea P. , Puta M.
Published: April 2007

We will prove the equivalence of three methods, the so called energy methods, in order to establish the stability of an equilibrium point for a dynamical system. We will illustrate by examples that this result simplifies enormously the amount of computations especially when the stability cannot be decided with one of the three methods.
Electrostatics of proteins in dielectric solvent continua. II. First applications in molecular dynamics simulations
Authors: Stork Martina , Tavan Paul
Published: April 2007

In the preceding paper by Stork and Tavan, [J. Chem. Phys. 126, 165105 (2007)], the authors have reformulated an electrostatic theory which treats proteins surrounded by dielectric solvent continua and approximately solves the associated Poisson equation [B. Egwolf and P. Tavan, J. Chem. Phys. 118, 2039 (2003)]. The resulting solution comprises analytical expressions for the electrostatic reaction field (RF) and potential, which are generated within the protein by the polarization of the surrounding continuum. Here the field and potential are represented in terms of Gaussian RF dipole densities localized at the protein atoms. Quite like in a polarizable force field, also the RF dipole at a given protein atom is induced by the partial charges and RF dipoles at the other atoms. Based on the reformulated theory, the authors have suggested expressions for the RF forces, which obey Newton’s third law. Previous continuum approaches, which were also built on solutions of the Poisson equation, used to violate the reactio principle required by this law, and thus were inapplicable to molecular dynamics (MD) simulations. In this paper, the authors suggest a set of techniques by which one can surmount the few remaining hurdles still hampering the application of the theory to MD simulations of soluble proteins and peptides. These techniques comprise the treatment of the RF dipoles within an extended Lagrangian approach and the optimization of the atomic RF polarizabilities. Using the well-studied conformational dynamics of alanine dipeptide as the simplest example, the authors demonstrate the remarkable accuracy and efficiency of the resulting RF-MD approach.
Effect of a noncircular plasma cross section on the ideal (1, 1) mode in low-shear tokamaks
Authors: Wahlberg C.
Published: April 2007

The effect of a noncircular shape of the plasma cross section on the ideal magnetohydrodynamic (MHD) stability of the (m,n)=(1,1) internal kink, or quasi-interchange (QI), mode in toroidal plasmas, where the safety factor q is close to unity in a wide area in the plasma core, is analyzed. The analysis is based on previously derived perturbation expansions of the ideal MHD equations for the (1, 1) mode, in the inverse aspect ratio, and in the ellipticity and the triangularity of the plasma cross section. For equilibria having a parabolic pressure profile and a constant central q=q0, with 0<q0−1⪡1, a simple analytical formulation of the stability problem is obtained, and an expression for the eigenfunction in terms of a Bessel function is found. Furthermore, noncircularity of the cross section is found to induce a whole spectrum of (1, 1) ideal modes with eigenvalues approaching the continuum (ω∕ωA)2=(q0−1)2∕3 as the number of nodes in the radial direction goes to infinity. The QI mode is the most unstable mode in this class. If the pressure is low and/or the radius of the low-shear region is small, noncircularity has a small and, usually, destabilizing effect on the QI mode, whereas in plasmas with high pressure and a large radius of the low-shear region, the combined effects of vertical elongation and positive triangularity lead to a substantial improvement of the stability of this mode compared with the situation in plasmas with circular cross section.
Cellular automaton modeling of mesospheric optical emissions: Sprites
Authors: Hayakawa M. , Iudin D. I. , Mareev E. A. , Trakhtengerts V. Y.
Published: April 2007

This paper presents a new attempt to model two-dimensional mesospheric optical emissions named sprites with the use of a cellular automaton network. A large-scale model of sprites based on the phenomenological percolation-like probabilistic approach is developed to model streamer discharges in sprites. It is shown that a sprite is a self-affine structure rather than a simple fractal one, and that this self-affine structure is tightly connected with directed percolation phenomena. The system is found to evolve in the vicinity of the percolation threshold, which results in a wide variety of sprite characteristics even under similar initial conditions. The approach developed allows us to estimate a maximum size of the discharge pattern to be formed.