bluuebunny/crossref_metadata_2025 huggingface dataset:
Ground‐based measurements of airborne Saharan dust in marine environment during the NAMMA field experiment
Authors: Jeong Myeong‐Jae , Tsay Si‐Chee , Ji Qiang , Hsu N. Christina , Hansell Richard A. , Lee Joonsuk
Published: October 2008

Several episodes of airborne mineral dust transported from the Saharan deserts were observed at Sal Island, Cape Verde for 2–28 September 2006 during the NASA African Monsoon Multidisciplinary Analyses (NAMMA) field experiment. Dust particles were mixed with marine background aerosols when the dust layers descended into the marine boundary layer. A new method is developed to derive the optical properties of dust when mixed with maritime aerosols. The derived single scattering albedo and mass scattering efficiency differed significantly between two selected cases leading to differences in their direct radiative effects. Back‐trajectory analyses suggest that the two cases were influenced by dust particles originating from different source regions over North Africa. This stresses the importance of resolving dust optical properties in sub‐regional scales to attain a better assessment of the role of airborne dust on the climate system.
Net ecosystem fluxes of isoprene over tropical South America inferred from Global Ozone Monitoring Experiment (GOME) observations of HCHO columns
Authors: Barkley Michael P. , Palmer Paul I. , Kuhn Uwe , Kesselmeier Juergen , Chance Kelly , Kurosu Thomas P. , Martin Randall V. , Helmig Detlev , Guenther Alex
Published: October 2008

We estimate isoprene emissions over tropical South America during 1997–2001 using column measurements of formaldehyde (HCHO) from the Global Ozone Monitoring Experiment (GOME) satellite instrument, the GEOS‐Chem chemistry transport model, and the MEGAN (Model of Emissions of Gases and Aerosols from Nature) bottom‐up isoprene inventory. GEOS‐Chem is qualitatively consistent with in situ ground‐based and aircraft concentration profiles of isoprene and HCHO, and GOME HCHO column data (r = 0.41; bias = +35%), but has less skill in reproducing wet season observations. Observed variability of GOME HCHO columns over South America is determined largely by isoprene and biomass burning. We find that the column contributions from other biogenic volatile organic compounds (VOC) are typically smaller than the column fitting uncertainty. HCHO columns influenced by biomass burning are removed using Along Track Scanning Radiometer (ATSR) firecounts and GOME NO2 columns. We find that South America can be split into eastern and western regions, with fires concentrated over the eastern region. A monthly mean linear transfer function, determined by GEOS‐Chem, is used to infer isoprene emissions from observed HCHO columns. The seasonal variation of GOME isoprene emissions over the western region is broadly consistent with MEGAN (r = 0.41; bias = −25%), with largest isoprene emissions during the dry season when the observed variability is consistent with knowledge of temperature dependence. During the wet season, other unknown factors play a significant role in determining observed variability.
Body Composition, Insulin Sensitivity, and Cardiovascular Disease Profile in Healthy Europeans
Authors: Boorsma Wiebe , Snijder Marieke B. , Nijpels Giel , Guidone Caterina , Favuzzi Angela M.R. , Mingrone Geltrude , Kostense Piet J. , Heine Robert J. , Dekker Jacqueline M.
Published: October 2008

Objective: To assess whether insulin sensitivity can explain the associations of leg‐fat mass (LFM) and trunk‐fat mass (TFM) with the cardiovascular disease (CVD) risk profile in healthy European men and women.

Methods and Procedures: We studied 142 healthy men and women of a multicenter European study on insulin sensitivity, aged 30–60 years, from the centres in Hoorn, the Netherlands and Rome, Italy. Whole‐body dual‐energy X‐ray absorptiometry (DXA) was used to determine fat and lean soft tissue mass in the trunk and legs. Fasting glucose, insulin, and lipid levels were measured. Insulin sensitivity (M/I‐ratio) was measured during a euglycemic‐hyperinsulinemic clamp. Associations between fat distribution and CVD risk factors were studied with linear regression analyses with adjustment for other body compartments, and subsequent adjustment for insulin sensitivity.

Results: In men, larger LFM was significantly and independently associated with lower triglyceride levels (TGs) and higher high‐density lipoprotein (HDL) cholesterol (P < 0.10) and tended to be associated also with lower low‐density lipoprotein (LDL) cholesterol, and lower fasting insulin levels. In women, larger LFM was associated with favorable values of all CVD risk factors, although the associations were not statistically significant. In both sexes, larger TFM was independently and significantly associated with unfavorable values of most CVD risk factors, and most associations did not markedly change after adjustment for insulin sensitivity.

Discussion: In a relatively young and healthy European population, larger LFM is associated with a lower and TFM with a higher cardiovascular and metabolic risk, which can not be explained by insulin sensitivity.
Developmental Changes of Gut Microflora and Enzyme Activity in Rat Pups Exposed to Fat‐rich Diet
Authors: Mozeš Štefan , Bujňáková Dobroslava , Šefčíková Zuzana , Kmeť Vladimír
Published: October 2008

The aim of this study was to investigate the effect of a high‐fat (HF)/energy diet on the intestinal microbiota, the alkaline phosphatase (AP) activity, and related parameters of growth and obesity during the suckling and weaning periods in male Sprague‐Dawley rats. From birth, nutrition in suckling pups was manipulated by feeding rat dams either HF or a standard diet, and then after weaning, by exposure of experimental pups to the HF, and control rats to normal diet. On days 15, 20, 40 the numbers of 2 microbial groups, i.e., Bacteroides/Prevotella (BAC) and the Lactobacillus/Enterococcus (LAB) in the jejunum, were determined by fluorescentin situhybridization technique, and the AP activity was assayed histochemically. During all investigated periods HF pups gained body fat more rapidly than control animals, but from weaning they displayed significantly stunted growth resulting in final body weight loss. Obesity in HF rats was also accompanied by higher LAB and lower numbers of BAC and with permanently higher AP activity. Correlation of these data showed significant negative correlation between LAB, AP, and weight gain and energy efficiency, and significant positive correlation of BAC and AP activity with body fat. These data support the concept that postnatal nutritional experience represents an important factor affecting the ontogeny of intestinal microbial communities and intestinal function. These acquired changes could be a component of regulatory mechanisms involved in adverse and/or positive consequences of HF diet for adiposity, body weight, and energy‐balance control in later life.
Common Genetic Components of Obesity Traits and Serum Leptin
Authors: Hasselbalch Ann L. , Benyamin Beben , Visscher Peter M. , Heitmann Berit L. , Kyvik Kirsten O. , Sørensen Thorkild I.A.
Published: October 2008

To estimate common and distinct genetic influences on a panel of obesity‐related traits and serum leptin level in adults. In a cross‐sectional study of 625 Danish, adult, healthy, monozygotic, and same‐sex dizygotic twin pairs of both genders, we carried out detailed anthropometry (height, weight, waist and hip, and skin‐fold thickness, body composition assessment by bioimpedance (fat mass and fat‐free mass), and measurement of serum leptin level. Bivariate variance component analyses estimated the additive genetic correlations between these measurements. The genetic correlations between the traits for overall fatness (BMI and fat mass index, kg/m2) were 0.94 in men and 0.98 in women, and their correlations with the various local fatness measures ranged from 0.49 to 0.83 in men and from 0.70 to 0.87 in women. The correlations between the truncal measures (waist circumference and truncal skin folds) and between the peripheral measures (hip circumference and peripheral skin folds) were 0.57 and 0.47 in men and 0.71 and 0.70 in women, respectively. The correlations between the truncal and peripheral measures ranged between 0.49 and 0.72 in men and between 0.61 and 0.82 in women. For leptin vs. the various measures of overall and local fatness the correlations ranged from 0.54 to 0.74 in men and from 0.48 to 0.75 in women. All correlations were significantly <1.00. The study supports control of overall fat mass and peripheral and truncal fat mass by both shared and different genetic components, which suggests that it is important to distinguish between the different phenotypes in the search for genes involved in the development of obesity.
Insulin and epidermal growth factor suppress basal glucose-6-phosphatase catalytic subunit gene transcription through overlapping but distinct mechanisms
Authors: Onuma Hiroshi , Oeser James K. , Nelson Bryce A. , Wang Yingda , Flemming Brian P. , Scheving Lawrence A. , Russell William E. , O'brien Richard M.
Published: October 2008

The G6Pase (glucose-6-phosphatase catalytic subunit) catalyses the final step in the gluconeogenic and glycogenolytic pathways, the hydrolysis of glucose-6-phosphate to glucose. We show here that, in HepG2 hepatoma cells, EGF (epidermal growth factor) inhibits basal mouse G6Pase fusion gene transcription. Several studies have shown that insulin represses basal mouse G6Pase fusion gene transcription through FOXO1 (forkhead box O1), but Stoffel and colleagues have recently suggested that insulin can also regulate gene transcription through FOXA2 (forkhead box A2) [Wolfrum, Asilmaz, Luca, Friedman and Stoffel (2003) Proc. Natl. Acad. Sci. 100, 11624–11629]. A combined GR (glucocorticoid receptor)–FOXA2 binding site is located between −185 and −174 in the mouse G6Pase promoter overlapping two FOXO1 binding sites located between (−188 and −182) and (−174 and −168). Selective mutation of the FOXO1 binding sites reduced the effect of insulin, whereas mutation of the GR/FOXA2 binding site had no effect on the insulin response. In contrast, selective mutation of the FOXO1 and GR/FOXA2 binding sites both reduced the effect of EGF. The effect of these mutations was additive, since the combined mutation of both FOXO1 and GR/FOXA2 binding sites reduced the effect of EGF to a greater extent than the individual mutations. These results suggest that, in HepG2 cells, GR and/or FOXA2 are required for the inhibition of basal G6Pase gene transcription by EGF but not insulin. EGF also inhibits hepatic G6Pase gene expression in vivo, but in cultured hepatocytes EGF has the opposite effect of stimulating expression, an observation that may be explained by a switch in ErbB receptor sub-type expression following hepatocyte isolation.
Cytoprotective effects of IAPs revealed by a small molecule antagonist
Authors: Galbán Stefanie , Hwang Clara , Rumble Julie M. , Oetjen Karolyn A. , Wright Casey W. , Boudreault Alain , Durkin Jon , Gillard John W. , Jaquith James B. , Morris Stephen J. , Duckett Colin S.
Published: October 2008

Deregulated expression of members of the IAP (inhibitor of apoptosis) family has been identified in a wide variety of neoplastic cells, and synthetic IAP antagonists represent a promising novel class of chemotherapeutic agents. Early work focused on the ability of these compounds to block the caspase-inhibitory function of XIAP (X-linked IAP). However, recent studies have shown that IAP antagonists, although primarily designed to target XIAP, trigger ubiquitin-mediated degradation of two related proteins, c-IAP (cellular IAP) 1 and c-IAP2, and through this process potentiates the death of tumour cells via autocrine cellular-signalling pathways. In this context, the relative contribution of XIAP as a target of this class of compounds is unclear. In the present study, we examine the involvement of XIAP using a recently described synthetic IAP antagonist, AEG40730, and through comparison of a human XIAP-depleted tumour cell line with its isogenic wild-type control line. Treatment with nanomolar concentrations of AEG40730 resulted in the loss of both XIAP and c-IAP1 proteins, albeit with different kinetics. Although XIAP-deficient HCT116 cells retained some sensitivity to external apoptotic stimuli, the results suggest that IAP antagonists, such as AEG40730, exert their apoptosis-enhancing effects through XIAP in addition to the c-IAPs. These results indicate that IAP antagonists can target multiple IAPs to augment distinct pro-apoptotic signalling pathways, thereby revealing the potential for these compounds in cancer therapy and underscoring the promise of IAP-targeted therapies.
More knocks to the oxidation hypothesis for vascular disease?
Authors: Mullan Adam , Sattar Naveed
Published: October 2008

The oxidation hypothesis for CHD (coronary heart disease) is attractive; however, the almost universal failure of antioxidant vitamin supplementation as a CVD (cardiovascular disease) risk modifier challenges the oxidation hypothesis, at least as a concept that easily ‘translates’ into clinical benefit for the population. At the same time, quality prospective data on lipid or protein oxidation markers as predictors of vascular events are sparse. In the present issue of Clinical Science, Woodward and co-workers provide much needed prospective data examining the relationship between markers of oxidative damage and CHD outcome in a general population. Despite noting the expected associations between several established CHD risk factors and CHD events, no significant link was observed between measured oxidation markers and CHD risk, a finding which further challenges the oxidation hypothesis for CHD.
Breit interaction contribution to parity violating potentials in chiral molecules containing light nuclei
Authors: Berger Robert
Published: October 2008

The importance of the Breit interaction for an accurate prediction of parity violating energy differences between enantiomers is studied within electroweak quantum chemical frameworks. Besides two-electron orbit-orbit and spin-spin coupling contributions, the Breit interaction gives rise to the spin-other-orbit coupling term of the Breit–Pauli Hamiltonian. The present numerical study demonstrates that neglect of this latter term leads in hydrogen peroxide (H2O2) to relative deviations in the parity violating potential (Vpv) by about 10%, whereas further relativistic corrections accounted for within a four-component Dirac–Hartree–Fock–Coulomb (DHFC) framework remain smaller, below 5%. Thus, the main source of discrepancy between previous one-component based (coupled perturbed) Hartree–Fock (HF) and four-component Dirac–Hartree–Fock results for parity violating potentials in H2O2 is the neglect of the Breit contribution in DHFC. In heavier homologs of hydrogen peroxide the relative contribution of the spin-other-orbit coupling term to Vpv decreases with increasing nuclear charge, whereas other relativistic effects become increasingly important. As shown for the H2X2 (X=O,S,Se,Te,Po) series of molecules and for CHBrClF, to a good approximation these other relativistic influences on Vpv can be accounted for in one-component based HF calculations with the help of relativistic enhancement factors proposed earlier in the theory of atomic parity violation.
Effect of free electrons on nanoparticle charging in a negative direct current corona charger
Authors: Aliat A. , Tsai C.-J. , Hung C.-T. , Wu J.-S.
Published: October 2008

A two-dimensional numerical model is proposed in this letter to take into account the effects of free electrons on nanoparticle charging in a negative direct current wire-tube corona charger. Numerical results are in excellent agreement with the experimental data by using a capturing probability of electrons onto nanoparticles with a value of 0.013. These free electrons contribute greatly to the charging efficiency at high products of mean ion concentration and mean residence time, which explains very well the large discrepancy found in earlier models that considered only negative ions.
Comments related to my paper “The contact angle in capillarity”
Authors: Finn Robert
Published: October 2008

In Phys. Fluids 19, 118105 (2007), I. Lunati disputes my earlier paper [Phys. Fluids 18, 047102 (2006)], in which I pointed out an anomaly arising from Thomas Young’s concept of solid/fluid surface tension. The present article examines Lunati’s reasoning and concludes that my earlier paper is correct.
Molecular simulation of the swelling of polyelectrolyte gels by monovalent and divalent counterions
Authors: Yin De-Wei , Horkay Ferenc , Douglas Jack F. , de Pablo Juan J.
Published: October 2008

Permanently crosslinked polyelectrolyte gels are known to undergo discontinuous first-order volume phase transitions, the onset of which may be caused by a number of factors. In this study we examine the volumetric properties of such polyelectrolyte gels in relation to the progressive substitution of monovalent counterions by divalent counterions as the gels are equilibrated in solvents of different dielectric qualities. We compare the results of coarse-grained molecular dynamics simulations of polyelectrolyte gels with previous experimental measurements by others on polyacrylate gels. The simulations show that under equilibrium conditions there is an approximate cancellation between the electrostatic contribution and the counterion excluded-volume contribution to the osmotic pressure in the gel-solvent system; these two contributions to the osmotic pressure have, respectively, energetic and entropic origins. The finding of such a cancellation between the two contributions to the osmotic pressure of the gel-solvent system is consistent with experimental observations that the swelling behavior of polyelectrolyte gels can be described by equations of state for neutral gels. Based on these results, we show and explain that a modified form of the Flory–Huggins model for nonionic polymer solutions, which accounts for neither electrostatic effects nor counterion excluded-volume effects, fits both experimental and simulated data for polyelectrolyte gels. The Flory–Huggins interaction parameters obtained from regression to the simulation data are characteristic of ideal polymer solutions, whereas the experimentally obtained interaction parameters, particularly that associated with the third virial coefficient, exhibit a significant departure from ideality, leading us to conclude that further enhancements to the simulation model, such as the inclusion of excess salt, the allowance for size asymmetric electrolytes, or the use of a distance-dependent solvent dielectricity model, may be required. Molecular simulations also reveal that the condensation of divalent counterions onto the polyelectrolyte network backbone occurs preferentially over that of monovalent counterions.
Observation of the inductive to helicon mode transition in a weakly magnetized solenoidal inductive discharge
Authors: Lee Min-Hyong , Chung Chin-Wook
Published: October 2008

A mode transition from an inductive mode to a helicon mode is observed in a solenoidal inductive discharge immersed in a weak dc magnetic field. The measured electron temperature and the plasma density at the reactor radial boundary show a sudden increase when the magnetic field strength reaches the critical value and the electron cyclotron frequency exceeds the rf driving frequency. These increases are due to the electron heating by the helicon wave. Such increases in the temperature and the density are not observed at the plasma center because the helicon wave cannot propagate to the center of the solenoidal type reactor unless the magnetic field is very high. These results show that the transition of the discharge from the inductive to the helicon mode occurs at the critical magnetic field strength.
Comparative study of the structures of copper, silver, and gold icosamers: Influence of metal type and charge state
Authors: Lechtken Anne , Neiss Christian , Stairs Jason , Schooss Detlef
Published: October 2008

We present a comparative study on the structural properties of the coinage metal icosamers Cu20+/−, Ag20+/−, and Au20+/−. Using trapped ion electron diffraction measurements in combination with density functional structure calculations we find distinct structural differences depending on the cluster material and the charge state: Cu20−, Cu20+, as well as Ag20+ prefer icosahedral structures. Ag20− adopts a rearranged, distorted icosahedral structure. While Au20− is tetrahedral, Au20+ cannot be described satisfyingly by a single isomer alone. Here a mixture of tetrahedral and distorted icosahedral structures is suggested. The influence of material and charge on the structural properties of the coinage metal icosamers is discussed.
Self-assembly of grafted Y-shaped ABC triblock copolymers in solutions
Authors: Yin Yuhua , Jiang Run , Li Baohui , Jin Qinghua , Ding Datong , Shi An-Chang
Published: October 2008

Self-assembled morphologies of grafted Y-shaped ABC triblock copolymers are investigated using a simulated annealing method. The block copolymers are composed of two incompatible arms (A and B) and a short stem (C), with the C-stems grafted onto a flat surface. A rich array of novel morphologies is discovered. The formation of these morphologies is controlled by polymer grafting density, the incompatibility between the A-B-blocks, as well as the quality and selectivity of the solvents. In particular, it is observed that solvent selectivity drives lateral and/or perpendicular microphase separation. A phase diagram for systems with low grafting density is constructed. It is predicted that multiple morphological transitions, such as these from mixed or core-shell micelles to internally segregated micelles, to hamburger-like micelles, to segmented wormlike micelles, to connected micelles, and to split micelles, can be induced by varying either the incompatibility between the two arms or the quality of the solvents. These results are consistent with previous experiments and theories.
Folding kinetics of proteins and cold denaturation
Authors: Collet Olivier
Published: October 2008

Folding kinetics of a lattice model of protein is studied. It uses the random energy model for the intrachain couplings and a temperature dependent free energy of solvation derived from a realistic hydration model of apolar solutes. The folding times are computed using Monte Carlo simulations in the region of the phase diagram where the chain occurs in the native structure. These folding times are roughly equals for the temperatures of cold and warm denaturations for a large range of solvent quality. Between these temperatures, the folding times reach maxima and thus, at low temperatures, the kinetics of the chain always speeds up as the temperature is decreased. The study of the conformational space as function of the temperature permits to elucidate this phenomenon. At low temperature, it shows that the activation barriers of the system decrease faster than the temperature as the temperature is decreased. At high temperature, the rate of the barriers over the temperature decreases as the temperature is increased because the height of the barrier is almost constant.
Calculation of the atomic spin densities and energy band gaps of carbon high-spin aromatic (pi) large macromolecular systems
Authors: Álvarez Collado J. R.
Published: October 2008

In this work we have calculated the atomic spin densities and energy band gaps of three kinds of large carbon unlocalized high-spin aromatic systems, consisting of 1000 to 10 000 atoms. The selected systems, nanotubes, graphenes, and polyaryls, have obvious theoretical and technical interest. The results obtained for nanotubes and graphenes confirm and expand the ones published by other authors. The results for polyaryls are totally new.
Imaging the pair-correlated dynamics and isotope effects of the Cl+CH2D2 reaction
Authors: Wu Yen-Tien , Liu Kopin
Published: October 2008

By using a time-sliced (ion) velocity-imaging technique, the title reaction was investigated to interrogate the pair-correlated dynamics of HCl (DCl) in concomitance with the CHD2 or CHD2 ground-state product under the crossed-beam conditions. Product pair-correlated excitation functions, vibrational branching ratios, and angular distributions were obtained over a wide range of collision energies, from 2 to 22 kcal/mol. Two distinct reaction mechanisms were uncovered. Both the dominant ground-state reaction of Cl+CH2D2(v=0)→HCl(v=0)/DCl(v=0)+CHD2(00)/CH2D(00) and the reaction forming the same product pairs from bend-excited CH2D2 reactants proceed through direct mechanisms, which shift from a rebound dynamics near thresholds to a peripheral dynamics at higher Ec. Reactivity of forming the HCl(v=1)/DCl(v=1,2)+CHD2(00)/CH2D(00) product pairs from ground-state reactants is small, yet shows dynamics pattern characteristics of a resonant reaction pathway. Significant spin-orbit reactivity of Cl∗(P21/2) was discovered, and its mechanism appears to be also mediated by the resonant reaction pathway. Comparing the dynamical attributes of the H- and D-atom transfer channels, remarkable isotope effects are found—in line with the previous findings in the Cl+CH4/CD4 and Cl+CHD3 reactions.
Enhanced uniaxial magnetic anisotropy in Fe31Co69 thin films on GaAs(001)
Authors: Bianco F. , Bouchon P. , Sousa M. , Salis G. , Alvarado S. F.
Published: October 2008

We report on the effect of postgrowth annealing on the magnetic anisotropy of Fe31Co69 thin epitaxial films, 1–9 nm thick, and grown on GaAs(001) substrates. Hysteresis curves obtained by means of the magneto-optical Kerr effect reveal an in-plane uniaxial magnetic anisotropy with the easy axis typically along the [110] substrate direction. The effective in-plane and perpendicular anisotropy constants, Kueff and K⊥eff, exhibit a steep quasilinear increase with the annealing temperature. Annealing a 1.9-nm-thick film for 10 min at 300 °C results in an increase in Kueff from the as-grown value of 8.9×103 to 1.1×105 J/m3. The slope of Kueff versus annealing temperature increases approximately as the inverse of the film thickness. These observations can be accounted for by a thermally induced structural modification occurring in the ferromagnet-semiconductor interface. Film-strain measurements performed by x-ray grazing-incidence diffraction indicate that the postgrowth annealing evolution of Kueff and K⊥eff are not predominantly induced by a magnetoelastic effect associated with strain changes in the thin film, but rather by modifications of the interface atom bonding, leading to an enhanced magnetocrystalline anisotropy at the ferromagnet-semiconductor interface.
Hole trap related hysteresis in pentacene field-effect transistors
Authors: Ucurum C. , Goebel H. , Yildirim F. A. , Bauhofer W. , Krautschneider W.
Published: October 2008

We have investigated hysteresis in pentacene-based field-effect transistors with SiO2 as gate dielectric. A clear hysteresis behavior in transfer and output characteristics is reported. Measurements show that the observed hysteresis is due to hole trapping in the pentacene film. Long time constants of the trapping/detrapping mechanism are demonstrated through transient measurements. An initialization routine to be performed prior to measurements is proposed to enable reproducible and reliable measurements on pentacene transistors.
Evidence of “crossed” transitions in dots-in-a-well structures through waveguide absorption measurements
Authors: Visimberga G. , Rainò G. , Salhi A. , Tasco V. , Todaro M. T. , Martiradonna L. , De Giorgi M. , Passaseo A. , Cingolani R. , De Vittorio M.
Published: October 2008

In-plane absorption measurements were performed at room temperature by means of a waveguide transmission setup on a Stranski–Krastanov InAs dots-in-a-well system emitting at 1.3μm embedded in a p-i-n structure. The polarization dependence of quantum dot (QD) absorption was exploited to resolve its discrete and continuous spectral components and study them separately under reverse bias application. The quantum confined Stark effect observed in the discrete spectral component gave evidence of an upward built-in QD dipole of about 9.5×10−29Cm. The continuous component was found to originate from electronic transitions involving a QD state and a quantum well state.
Reversible growth-mode transition in SrRuO3 epitaxy
Authors: Bachelet R. , Sánchez F. , Santiso J. , Fontcuberta J.
Published: October 2008

It is known that a transition from layer-by-layer (LbL) to step-flow (SF) can occur at the earliest stages of SrRuO3 growth on SrTiO3(001). We report here the observation of a reversible transition between these two-dimensional growth modes that can occur at any SrRuO3 thickness, tuned by short growth interruption. We show that under SF mode, growth interruption allows step-edge straightening, thus resulting in enhanced island nucleation on locally wider terraces and reduced adatom incorporation at step edges. As a result, the LbL mode is recovered. This reversible transition critically influences the growing-layer morphology and is of crucial interest in epitaxial-heterostructure fabrication.
Effect of microwave frequency on breakdown and electron energy distribution function using a global model
Authors: Nam Sang Ki , Verboncoeur John P.
Published: October 2008

Global models (GMs) have proven a key modeling tool for the plasma processing field due to simplicity and speed. However, a GM requires specification of the electron energy distribution function (EEDF). The assumption of a Maxwellian EEDF leads to inaccurate reaction rate coefficients and results in error in plasma parameter prediction in high power microwave (HPM) driven discharges. Recently, a GM was developed with a pressure-independent enhanced EEDF to improve fidelity for modeling HPM breakdown. In this work, the GM is extended to 2 decades in frequency, and the frequency effect on HPM breakdown and the EEDF is investigated.
Pulsed laser deposition of ferromagnetic Zn0.95Co0.05O thin films
Authors: Gacic Milan , Adrian Hermann , Jakob Gerhard
Published: October 2008

Zn 0.95 Co 0.05 O thin films have been prepared by pulsed laser deposition at different preparation conditions. By optimizing the deposition parameters we were able to increase the reproducibility of our ferromagnetic films up to 50% as well as the magnetization to 2.3μB∕Co. The ferromagnetic properties could be improved by a special multilayered deposition technique. Investigations of the magnetic and magnetotransport properties showed a clear correlation between the magnetic properties and the deposition conditions as well as a clear dependence between the transport and the magnetic properties. This hints to an intrinsic origin of the ferromagnetism.
Meta-analysis of the published effects of HGP use on beef palatability in steers as measured by objective and sensory testing
Authors: Watson Ray
Published: October 2008

Evidence is presented that suggests strongly that hormone growth promotant (HGP) implantation has a negative effect on beef palatability. This is based on a meta-analysis of results reported in refereed papers that have appeared in the meat-science literature. To be included in this analysis, a paper must have reported results for control samples (no HGP) and treatment samples (HGP) for either objective testing (Warner-Bratzler shear-force) or consumer preference (tenderness score). The paper must also have reported estimates and standard errors. Further, we consider only the case of steers, and the M. longissimus dorsi (striploin). While most of these studies yielded non-significant differences, most gave an estimate indicating that the HGP treatment had a negative effect on beef palatability. When these results are combined using a meta-analysis, they provide significant evidence that the use of HGP implants negatively influences palatability.
Vulnerability of white matter towards antenatal hypoxia is linked to a species-dependent regulation of glutamate receptor subunits
Authors: Fontaine Romain H. , Olivier Paul , Massonneau Véronique , Leroux Philippe , Degos Vincent , Lebon Sophie , El Ghouzzi Vincent , Lelièvre Vincent , Gressens Pierre , Baud Olivier
Published: October 2008

White-matter damage is a leading cause of neurological handicap. Although hypoxia-ischemia and excitotoxicity are major pathogenic factors, a role for genetic influences was suggested recently. Thus, protracted gestational hypoxia was associated with white-matter damage (WMD) in rat pups but not in mouse pups. Indeed, microglial activation and vessel-wall density on postnatal days (P)1 and P10 were found increased in both mouse and rat pups, but cell death, astrogliosis, and myelination were only significantly altered in hypoxic rat pups. We investigated whether this species-related difference was ascribable to effects of antenatal hypoxia on the expression of glutamate receptor subunits by using immunocytochemistry, PCR, and excitotoxic double hit insult. Quantitative PCR in hypoxic mouse pups on P1 showed 2- to 4-fold down-regulation of the AMPA-receptor subunits -1, 2, and -4; of the kainate-receptor subunit GluR7; and of the metabotropic receptor subunits mGluR1, -2, -3, -5, and -7. None of the glutamate-receptor subunits was down-regulated in the hypoxic rat pups. NR2B was the only NMDA-receptor subunit that was down-regulated in hypoxic mice but not in hypoxic rat on P1. Ifenprodil administration to induce functional inhibition of NMDA containing NR2B-subunit receptors prevented hypoxia-induced myelination delay in rat pups. Intracerebral injection of a glutamate agonist produced a larger decrease in ibotenate-induced excitotoxic lesions in hypoxic mouse pups than in normoxic mouse pups. Gestational hypoxia may regulate the expression of specific glutamate-receptor subunits in fetal mice but not in fetal rats. Therefore, genetic factors may influence the susceptibility of rodents to WMD.
Crystal structure of the pressure-induced metallic phase of SiH4from ab initio theory
Authors: Kim D. Y. , Scheicher R. H. , Lebègue S. , Prasongkit J. , Arnaud B. , Alouani M. , Ahuja R.
Published: October 2008

Metallization of pure solid hydrogen is of great interest, not least because it could lead to high-temperature superconductivity, but it continues to be an elusive goal because of great experimental challenges. Hydrogen-rich materials, in particular, CH4, SiH4, and GeH4, provide an opportunity to study related phenomena at experimentally achievable pressures, and they too are expected to be high-temperature superconductors. Recently, the emergence of a metallic phase has been observed in silane for pressures just above 60 GPa. However, some uncertainty exists about the crystal structure of the discovered metallic phase. Here, we show by way of elimination, that a single structure that possesses all of the required characteristics of the experimentally observed metallic phase of silane from a pool of plausible candidates can be identified. Our density functional theory and GW calculations show that a structure with space groupP4/nbmis metallic at pressures >60 GPa. Based on phonon calculations, we furthermore demonstrate that theP4/nbmstructure is dynamically stable at >43 GPa and becomes the ground state at 97 GPa when zero-point energy contributions are considered. These findings could lead the way for further theoretical analysis of metallic phases of hydrogen-rich materials and stimulate experimental studies.
Computed tomography and magnetic resonance features of renal ewing sarcoma
Authors: Ekram T. , Elsayes K.M. , Cohan R.H. , Francis I.R.
Published: October 2008

Ewing sarcoma (ES) is a rare malignant tumor that primarily involves long and flat bones but can develop in almost any bone or soft tissue. ES accounts for 2.3–3.5% of tumors in patients under the age of 19, and is rarely found in the adult population. Sarcomas, in general, account for less than 1% of tumors in adults. Several reports of renal ES have been described in the pediatric population, but only a few cases have been described in the adult population. To the best of our knowledge, fewer than 10 cases of renal Ewing sarcoma in adults have been described in the English literature. None of these cases described the computed tomography (CT) and magnetic resonance imaging (MRI) features. We report a case of a 46-year-old woman, including CT and MRI characteristics.
Disruption of the Interaction between Transcriptional Intermediary Factor 1β and Heterochromatin Protein 1 Leads to a Switch from DNA Hyper- to Hypomethylation and H3K9 to H3K27 Trimethylation on theMESTPromoter Correlating with Gene Reactivation
Authors: Riclet Raphaël , Chendeb Mariam , Vonesch Jean-Luc , Koczan Dirk , Thiesen Hans-Juergen , Losson Régine , Cammas Florence
Published: October 2008

Here, we identified the imprinted mesoderm-specific transcript (MEST) gene as an endogenous TIF1β primary target gene and demonstrated that transcriptional intermediary factor (TIF) 1β, through its interaction with heterochromatin protein (HP) 1, is essential in establishing and maintaining a local heterochromatin-like structure on MEST promoter region characterized by H3K9 trimethylation and hypoacetylation, H4K20 trimethylation, DNA hypermethylation, and enrichment in HP1 that correlates with preferential association to foci of pericentromeric heterochromatin and transcriptional repression. On disruption of the interaction between TIF1β and HP1, TIF1β is released from the promoter region, and there is a switch from DNA hypermethylation and histone H3K9 trimethylation to DNA hypomethylation and histone H3K27 trimethylation correlating with rapid reactivation of MEST expression. Interestingly, we provide evidence that the imprinted MEST allele DNA methylation is insensitive to TIF1β loss of function, whereas the nonimprinted allele is regulated through a distinct TIF1β–DNA methylation mechanism.
UNC-18 Modulates Ethanol Sensitivity inCaenorhabditis elegans
Authors: Graham Margaret E. , Edwards Mark R. , Holden-Dye Lindy , Morgan Alan , Burgoyne Robert D. , Barclay Jeff W.
Published: October 2008

Acute ethanol exposure affects the nervous system as a stimulant at low concentrations and as a depressant at higher concentrations, eventually resulting in motor dysfunction and uncoordination. A recent genetic study of two mouse strains with varying ethanol preference indicated a correlation with a polymorphism (D216N) in the synaptic protein Munc18-1. Munc18-1 functions in exocytosis via a number of discrete interactions with the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein syntaxin-1. We report that the mutation affects binding to syntaxin but not through either a closed conformation mode of interaction or through binding to the syntaxin N terminus. The D216N mutant instead has a specific impairment in binding the assembled SNARE complex. Furthermore, the mutation broadens the duration of single exocytotic events. Expression of the orthologous mutation (D214N) in the Caenorhabditis elegans UNC-18 null background generated transgenic rescues with phenotypically similar locomotion to worms rescued with the wild-type protein. Strikingly, D214N worms were strongly resistant to both stimulatory and sedative effects of acute ethanol. Analysis of an alternative Munc18-1 mutation (I133V) supported the link between reduced SNARE complex binding and ethanol resistance. We conclude that ethanol acts, at least partially, at the level of vesicle fusion and that its acute effects are ameliorated by point mutations in UNC-18.
Analysis of Prelamin A Biogenesis Reveals the Nucleus to be a CaaX Processing Compartment
Authors: Barrowman Jemima , Hamblet Corinne , George Carolyn M. , Michaelis Susan
Published: October 2008

Proteins establish and maintain a distinct intracellular localization by means of targeting, retention, and retrieval signals, ensuring most proteins reside predominantly in one cellular location. The enzymes involved in the maturation of lamin A present a challenge to this paradigm. Lamin A is first synthesized as a 74-kDa precursor, prelamin A, with a C-terminal CaaX motif and undergoes a series of posttranslational modifications including CaaX processing (farnesylation, aaX cleavage and carboxylmethylation), followed by endoproteolytic cleavage by Zmpste24. Failure to cleave prelamin A results in progeria and related premature aging disorders. Evidence suggests prelamin A is imported directly into the nucleus where it is processed. Paradoxically, the processing enzymes have been shown to reside in the cytosol (farnesyltransferase), or are ER membrane proteins (Zmpste24, Rce1, and Icmt) with their active sites facing the cytosol. Here we have reexamined the cellular site of prelamin A processing, and show that the mammalian and yeast processing enzymes Zmpste24 and Icmt exhibit a dual localization to the inner nuclear membrane, as well as the ER membrane. Our findings reveal the nucleus to be a physiologically relevant location for CaaX processing, and provide insight into the biology of a protein at the center of devastating progeroid diseases.
Isoform and Splice-Variant Specific Functions of Dynamin-2 Revealed by Analysis of Conditional Knock-Out Cells
Authors: Liu Ya-Wen , Surka Mark C. , Schroeter Thomas , Lukiyanchuk Vasyl , Schmid Sandra L.
Published: October 2008

Dynamin (Dyn) is a multifunctional GTPase implicated in several cellular events, including endocytosis, intracellular trafficking, cell signaling, and cytokinesis. The mammalian genome encodes three isoforms, Dyn1, Dyn2, and Dyn3, and several splice variants of each, leading to the suggestion that distinct isoforms and/or distinct splice variants might mediate distinct cellular functions. We generated a conditional Dyn2 KO cell line and performed knockout and reconstitution experiments to explore the isoform- and splice variant specific cellular functions of ubiquitously expressed Dyn2. We find that Dyn2 is required for clathrin-mediated endocytosis (CME), p75 export from the Golgi, and PDGF-stimulated macropinocytosis and cytokinesis, but not for other endocytic pathways. Surprisingly, CME and p75 exocytosis were efficiently rescued by reintroduction of Dyn2, but not Dyn1, suggesting that these two isoforms function differentially in vesicular trafficking in nonneuronal cells. Both isoforms rescued macropinocytosis and cytokinesis, suggesting that dynamin function in these processes might be mechanistically distinct from its role in CME. Although all four Dyn2 splice variants could equally restore CME, Dyn2ba and -bb were more effective at restoring p75 exocytosis. This splice variant specificity correlated with their differential targeting to the Golgi. These studies reveal isoform and splice-variant specific functions for Dyn2.
Inhibition of Cell Growth and Cellular Protein, DNA and RNA Synthesis in Human Hepatoma (HepG2) Cells by Ethanol Extract of Abnormal Savda Munziq of Traditional Uighur Medicine
Authors: Upur Halmurat , Yusup Abdiryim , Baudrimont Isabelle , Umar Anwar , Berke Benedicte , Yimit Dilxat , Lapham Jaya Conser , Creppy Edmon E. , Moore Nicholas
Published: October 2008

Abnormal Savda Munziq (ASMq) is a traditional Uighur medicinal herbal preparation, commonly used for the treatment and prevention of cancer. We tested the effects of ethanol extract of ASMq on cultured human hepatoma cells (HepG2) to explore the mechanism of its putative anticancer properties, using the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium (MTT) bromide, neutral red and lactate dehydrogenase (LDH) leakage assays, testing the incorporation of 3[H]‐leucine and 3[H]‐nucleosides into protein, DNA and RNA, and quantifying the formation of malondialdehyde‐thiobarbituric acid (MDA) adducts. ASMq ethanol extract significantly inhibited the growth of HepG2 and cell viability, increased the leakage of LDH after 48 hours or 72 hours treatment, in a concentration‐ and time‐dependent manner (P < .05). Cellular protein, DNA and RNA synthesis were inhibited in a concentration‐ and time‐dependent manner (P < .05). No significant MDA release in culture medium and no lipid peroxidation in cells were observed. The results suggest that the cytotoxic effects of ASMq ethanol extract might be related to inhibition of cancer cell growth, alteration of cell membrane integrity and inhibition of cellular protein, DNA and RNA synthesis.
Influence of Campylobacter fetus subsp. fetus on ram sperm cell quality
Authors: Zan Bar Tidhar , Yehuda Ronen , Hacham Tomer , Krupnik Sigal , Bartoov Benjamin
Published: October 2008

Campylobacter fetussubsp.fetusinfection can occur in female sheep, causing infertility or abortion. Despite extensive research on the effect of these bacteria on female fertility, little research has been done on the influence ofC. fetussubsp.fetuson the male factor. Our objective was to examine the influence ofC. fetussubsp.fetuson ram sperm. Motility index, percentage of live spermatozoa, meanαt value (an indication of the chromatin stability of the sperm cell) and percentage of sperm cells expressing the FAS receptor were measured in sperm incubated in the presence or absence ofC. fetussubsp.fetus. The motility index and viability of sperm incubated with the bacteria were lower than those of untreated sperm samples after 5 h. In bacteria-incubated sperm cells, the percentage expressing FAS receptor was already significantly elevated at 15 min. Bacteria-incubated sperm showed a greater prevalence of morphological damage. The bacteria were attached to tail and acrosome regions, and the sperm damage was concentrated in both the motility and chromatin regions. Bacteria-infected sperm cells showed a decrease in motility, increase in early acrosome reaction and chromatin damage. Similar effects were induced by incubation of the sperm with supernatants fromC. fetussubsp.fetuscultures. Thus this study demonstrates thatC. fetussubsp.fetushas a detrimental effect on the quality of ram sperm.
Identification and molecular analysis of βC–S lyase producing hydrogen sulfide in Streptococcus intermedius
Authors: Ito Shuntaro , Nagamune Hideaki , Tamura Haruki , Yoshida Yasuo
Published: October 2008

Hydrogen sulfide (H2S) is a toxic gas that induces the modification and release of haemoglobin in erythrocytes; however, it also functions in methionine biosynthesis in bacteria.βC–S lyase, encoded by thelcdgene, is responsible for bacterial H2S production through the cleavage ofl-cysteine. In this study, 26 of 29 crude extracts from reference and clinical strains ofStreptococcus intermediusproduced H2S froml-cysteine. The capacities in those strains were not higher than those in strains of the other anginosus group of streptococci,Streptococcus anginosusandStreptococcus constellatus, but were much greater than those in strains ofStreptococcus gordonii, which is known to have an extremely low capacity for H2S production. Incubation of the remaining three extracts withl-cysteine did not result in H2S production. Sequence analysis revealed that thelcdgenes from these three strains (S. intermediusstrains ATCC 27335, IMU151 and IMU202) contained mutations or small deletions. H2S production in crude extracts prepared fromS. intermediusATCC 27335 was restored by repairing thelcdgene sequence in genomic DNA. The kinetic properties of the purified recombinant protein encoded by the repairedlcdgene were comparable to those of native proteins produced by H2S-producing strains, whereas the truncated protein produced byS. intermediusATCC 27335 had no enzymic activity withl-cysteine orl-cystathionine. However, real-time PCR analysis indicated that thelcdgene in strains ATCC 27335, IMU151 and IMU202 is transcribed and regulated in a manner similar to that in the H2S-producing strain.
Rhodococcus equi infection in a patient with spinocellular carcinoma of unknown origin
Authors: Borghi Elisa , La Francesca Maria , Gazzola Lidia , Marchetti Giulia , Zonato Sabrina , Foa Paolo , d'Arminio Monforte Antonella , Morace Giulia
Published: October 2008

A Rhodococcus equi pulmonary infection in a 63-year-old man receiving chemotherapy and radiotherapy for spinocellular carcinoma is described. The patient, a knife-grinder, was promptly treated with levofloxacin plus amikacin followed by rifampicin for 2 months, and he is still in good clinical condition after an 8-month follow-up.