bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polypeptide binding specificities of Saccharomyces cerevisiae oligosaccharyltransferase accessory proteins Ost3p and Ost6p
Authors: Jamaluddin M. Fairuz B. , Bailey Ulla‐Maja , Tan Nikki Y.J. , Stark Anthony P. , Schulz Benjamin L. 
Published: March 2011

AbstractAsparagine‐linked glycosylation is a common and vital co‐ and post‐translocational modification of diverse secretory and membrane proteins in eukaryotes that is catalyzed by the multiprotein complex oligosaccharyltransferase (OTase). Two isoforms of OTase are present in Saccharomyces cerevisiae, defined by the presence of either of the homologous proteins Ost3p or Ost6p, which possess different protein substrate specificities at the level of individual glycosylation sites. Here we present in vitro characterization of the polypeptide binding activity of these two subunits of the yeast enzyme, and show that the peptide‐binding grooves in these proteins can transiently bind stretches of polypeptide with amino acid characteristics complementary to the characteristics of the grooves. We show that Ost6p, which has a peptide‐binding groove with a strongly hydrophobic base lined by neutral and basic residues, binds peptides enriched in hydrophobic and acidic amino acids. Further, by introducing basic residues in place of the wild type neutral residues lining the peptide‐binding groove of Ost3p, we engineer binding of a hydrophobic and acidic peptide. Our data supports a model of Ost3/6p function in which they transiently bind stretches of nascent polypeptide substrate to inhibit protein folding, thereby increasing glycosylation efficiency at nearby asparagine residues.
Local models of heterotic flux vacua: spacetime and worldsheet aspects
Authors: Israël D. , Carlevaro L. 
Published: March 2011

AbstractWe report on some recent progress in understanding heterotic flux compactifications, from a worldsheet perspective mainly. We consider local models consisting in torus fibration over warped Eguchi‐Hanson space and non‐Kähler resolved conifold geometries. We analyze the supergravity solutions and define a double‐scaling limit of the resolved singularities, defined such that the geometry is smooth and weakly coupled. We show that, remarkably, the heterotic solutions admit solvable worldsheet CFT descriptions in this limit. This allows in particular to understand the important role of worldsheet non‐perturbative effects.
Charged particle‐like branes in ABJM: A summary
Authors: Gutierrez N. , Lozano Y. , Rodriguez‐Gomez D. 
Published: March 2011

AbstractWe study the effect of adding lower dimensional brane charges to the 't Hooft monopole, di‐baryon and baryon vertex configurations in AdS4 × ℙ3. We show that these configurations capture the background fluxes in a way that depends on the induced charges, requiring additional fundamental strings to cancel the worldvolume tadpoles. The dynamics reveal that the charges must lie inside some interval, a situation familiar from the baryon vertex in AdS5 × S5 with charges. For the baryon vertex and the di‐baryon the number of fundamental strings must also lie inside an allowed interval. Some ideas about the existence of these bounds in relation to the stringy exclusion principle are given.
Cosmic strings in string perturbation theory
Authors: Skliros D. 
Published: March 2011

AbstractFundamental cosmic superstrings are defined in string perturbation theory in terms of vertex operators, which are loosely identified with arbitrarily excited macroscopic string states. We construct explicit normal ordered cosmic string vertex operators, which are given in terms of covariant coherent string states. We also write down the general expression for arbitrarily excited mass‐eigenstate covariant vertex operators, and discuss the construction of string wavepackets.
Mg and Si dopant incorporation and segregation in GaN
Authors: Schmidt Th. , Siebert M. , Flege J. I. , Figge S. , Gangopadhyay S. , Pretorius A. , Lee T.‐L. , Zegenhagen J. , Gregoratti L. , Barinov A. , Rosenauer A. , Hommel D. , Falta J. 
Published: March 2011

AbstractThe surface segregation of Mg and Si dopant species and their atomic incorporation sites in GaN films grown by metal‐organic vapour phase epitaxy (MOVPE) on sapphire (0001) substrates have been analysed by X‐ray photoemission spectro‐microscopy and X‐ray standing waves (XSW). As revealed by spectro‐microscopy, both Mg and Si tend to segregate to the surface. In case of Mg, an enhanced surface dopant concentration is found even after sputter‐removal of several tens of nanometres, which confirms a segregation mechanism proposed earlier [S. Figge et al., Appl. Phys. Lett. 81, 4748 (2002)]. Si doping has been found to result in the formation of facetted grooves in the GaN films. The surface silicon concentration at the facets is determined to be about 2.5 times higher as compared to the planar (0001) surface by micro‐spectroscopy. XSW results show that with increasing Mg dopant concentration, non‐substitutional lattice sites are progressively occupied. The results can quantitatively be explained by Mg atoms incorporated in an anti‐bixbyite‐like structure and is related to inversion domain boundaries. For Si doping, no evidence is found for the occupation of non‐substitutional sites. However, a decrease in crystal quality is observed with increasing Si concentration.magnified image
X‐ray photoemission micrograph of a Si doped GaN film showing a facetted groove at the lower left corner of the image. The local spectra (see inset) reveal Si enrichment at the facets.
Designing polymeric nanorod arrays for optical waveguide‐based biosensors
Authors: Gitsas Antonis , Lazzara Thomas D. , Yameen Basit , Steinhart Martin , Knoll Wolfgang , Duran Hatice 
Published: March 2011

AbstractThe optical waveguiding capabilities of polycyanurate thermoset nanorod (PCNs) arrays mounted on planar gold substrates were investigated using optical waveguide spectroscopy (OWS). The nanorods, with diameter of 60 and 150 nm, and length of 650 nm, are formed by thermal polymerization of cyanate ester oligomers within porous anodic aluminium oxide templates. We discuss the waveguiding properties of the PCNs arrays when the nanorod diameter is much smaller (<1/10) than the wavelength of the guided light. We monitored the changes in the waveguiding modes by exchanging the interrod filling environment with water, ethanol, and isopropanol. This study led to a sensing figure of merit as high as 196 reciprocal refractive index units, which is higher than that of other previously studied sensors based on angular modulation. Furthermore, numerical simulations were performed by applying an Effective Medium Theory (EMT) based on the Maxwell‐Garnett approximation for the prediction of the optical properties of anisotropic nanorod arrays. Simulations based on Fresnel equations were used for estimating the optimal fabrication geometry, with varying the nanorod diameter and the interrod distance. Based on these results, we introduce the applicability of the PCNs arrays platform as a concept in optical biosensors and other related applications (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thin‐film growth by random deposition of rod‐like particles on a square lattice
Authors: Forgerini F. L. , Figueiredo W. 
Published: March 2011

AbstractMonte Carlo simulations are employed to investigate the surface growth generated by deposition of particles of different sizes on a substrate, in one and two dimensions. The particles have a linear form, and occupy an integer number of cells of the lattice. The results of our simulations have shown that the roughness evolves in time following three different behaviors. The roughness in the initial times behaves as in the random deposition model, with an exponent β1 ≈ 1/2. At intermediate times, the surface roughness depends on the system dimensionality and, finally, at long times, it enters into the saturation regime, which is described by the roughness exponent α.The scaling exponents of the model are the same as those predicted by the Villain‐Lai‐Das Sarma equation for deposition in one dimension. For the deposition in two dimensions, we show that the interface width in the second regime presents an unusual behavior, described by a growing exponent β2, which depends on the size of the particles added to the substrate. If the linear size of the particle is two, we found that β2 < β1, otherwise it is β2 > β1, for all particles sizes larger than three. While in one dimension the scaling exponents are the same as those predicted by the Villain‐Lai‐Das Sarma equation, in two dimensions, the growth exponents are nonuniversal. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Development of High Strength Plates with Low Yield Ratio by the Combination of TMCP and Inter‐Critical Quenching and Tempering
Authors: Tang S. , Liu Z.Y. , Wang G.D. 
Published: March 2011

AbstractA new processing route of thermo‐mechanical processing (TMCP) followed by inter‐critical quenching and tempering (L‐T) was developed to produce 590MPa grade high strength plates based on a relatively lean composition of plain carbon manganese steels microalloyed with Nb, V and Ti. The effect of quenching temperatures on the evolution of microstructure and mechanical properties were investigated. The nano‐hardness measurements of martensite were performed with a nano‐indenter, which indicated that the fractions of as quenched and tempered martensite increased and their hardness values decreased with increasing quenching temperatures in the range from 760 °C to 810 °C. For both as quenched and tempered samples, ferrite grain sizes decreased with increasing quenching temperature in almost linear relationships. The yield strength increased with increasing the fraction of martensite while the tensile strength remained almost unchanged, leading to the increase of yielding ratio with increasing quenching temperatures. The optimum quenching temperature was determined to be around 760 °C in terms of strengths and yield ratio.
Adverse effects of neonatal exposure to 3,3′,4,4′,5,5′‐hexachlorobiphenyl on hormone levels and testicular function in male Sprague–Dawley rats
Authors: Xiao Wusheng , Zhang Jie , Liang Jiren , Zhu Hongyan , Zhou Zhijun , Wu Qing 
Published: March 2011

AbstractIn this study, we investigated the time‐course changes of hormone levels and sperm numbers in male Sprague–Dawley (SD) rats after neonatal exposure to 3,3′,4,4′,5,5′‐hexachlorobiphenyl (PCB169). Neonatal rats were given (through oral gavages) doses of 0, 0.025, 0.25, or 0.5 mg/kg‐day of PCB169 in corn oil from postnatal day 1 (PND1) to PND7. The rats were sacrificed at PND8, PND21, and PND90. PCB169 exposure was confirmed by the marked induction of liver CYP1A1 mRNA expression at these three time points. The testicular daily sperm production and the sperm counts of the epididymis cauda significantly decreased at PND90 compared to that of control. Although reductions in serum thyroxine and triiodothyronine levels occurred at all these three time points and at both PND21 and PND90, respectively, the mRNA expression of testicular thyroid hormone receptor α1 was suppressed significantly only at PND8. The serum and testicular testosterone (T) levels declined markedly at PND90 compared to the controls, but there was no effect at PND21. The mRNA expression of testicular steroidogenic factor 1 was inhibited markedly at the three time points, whereas those of StAR, P450c17, P450scc, and 3β‐HSD were suppressed significantly only at PND90 relative to the controls. PCB169 treatment had no effects on pituitary follicle‐stimulating hormone and luteinizing hormone levels and on their receptors' expression in the testes. These results indicate that neonatal exposure to PCB169 damages hormone levels and testicular function in the long‐term, resulting in persistent hypothyroidism and decreases in adult T levels and sperm counts. © 2011 Wiley Periodicals, Inc. Environ Toxicol, 2011.
Effects of bioreactive acrolein from automotive exhaust gases on human cells in vitro
Authors: Jaganjac Morana , Prah Iva Ozana , Cipak Ana , Cindric Marina , Mrakovcic Lidija , Tatzber Franz , Ilincic Petar , Rukavina Vinko , Spehar Branka , Vukovic Jelena Parlov , Telen Sanda , Uchida Koji , Lulic Zoran , Zarkovic Neven 
Published: March 2011

AbstractAcrolein is a toxic unsaturated aldehyde and widespread environmental pollutant produced during lipid peroxidation and also by burning of tobacco or liquid fuels. Inhalation or dermal exposure to acrolein could be toxic to organisms. This very reactive aldehyde has a strong affinity for binding to proteins thus forming pathogenic protein‐adducts. In the present study we have analyzed formation of bioreactive acrolein‐protein adducts in bovine serum albumin solution exposed to exhaust gases of mineral diesel fuel and of mineral diesel fuel supplemented with different amounts of a novel diesel fuel additive denoted Ecodiesel (produced by a genuine procedure of recycling of plant oils used for food preparation). The effects of acrolein‐protein adducts were tested on human microvascular endothelial cells and on human osteosarcoma cells that are sensitive to bioactivities of lipid peroxidation products. The results have shown a reduction of the bioreactive acrolein in exhaust gases when mineral diesel was supplemented with 5–20% Ecodiesel. Moreover, acrolein‐protein adducts obtained from mineral diesel supplemented with Ecodiesel were less toxic than those obtained from mineral diesel alone. Thus, we assume that supplementing mineral diesel fuel with Ecodiesel would be of benefit for the use of renewable energy, for environment and for human health due to reduced environmental pollution with bioreactive acrolein. © 2011 Wiley Periodicals, Inc. Environ Toxicol, 2011.
Ecotoxicological effects of Mikado® and Viper® on algae and daphnids
Authors: Marques C.R. , Gonçalves A.M.M. , Pereira R. , Gonçalves F. 
Published: March 2011

AbstractThe toxicity of single and combined formulated herbicides (Mikado® and Viper®) was assessed on several endpoints in species from two trophic levels: algae growth—Pseudokirchneriella subcapitata and Chlorella vulgaris—immobilization and life‐history traits (only for single compound toxicity) of daphnids—Daphnia longispina and Daphnia magna. Viper was the most toxic formulated herbicide. It was hypothesized that the toxicity of both formulated herbicides could have been enhanced by adjuvants, especially for Viper. In most cases, the sublethal endpoints were the most sensitive and affected by both formulations, comparatively to their acute effects. Concentration addition (CA) and independent action (IA) models provided an accurate description of Mikado and Viper joint action on algae growth and immobilization of daphnids, although significant deviations were always detected. A low‐dose antagonism and high‐dose synergism were identified for P. subcapitata, whereas C. vulgaris response deviated antagonistically from CA and synergistically from IA. For both daphnids, however, synergistic effects were observed for higher mixture concentrations. Under a regulatory standpoint, CA provided the most conservative estimation either because the mixture effects were overestimated or less subestimated than IA. Overall, the great sensitivity differences observed within species did not allow the conclusion that one trophic level was more tolerant than the other. Instead, P. subcapitata was always the most sensitive species to both herbicide formulations, followed by D. longispina, while D. magna and C. vulgaris were the most tolerant species. On a whole, further studies are needed toward a comprehensive understanding of herbicides mode of action, their effects at lower biological‐level endpoints, and under different mixture designs. © 2011 Wiley Periodicals, Inc. Environ Toxicol, 2012.
The protective effect of erdosteine on radiocontrast induced nephrotoxicity in rats
Authors: Yesilyurt Ahmet , Aydın Erden İsmail , Bilgiç İsmail , Erden Gönül , Albayrak Aynur 
Published: March 2011

AbstractAcute renal failure resulting from radiocontrast‐induced nephrotoxicity (RIN) is suggested to occur via medullary ischemia coupled with the generation of free radicals and oxidative injury to tubular cells. The aim of the present study was to assess the effects of erdosteine on prevention of RIN. Thirty‐three Wistar‐albino rats were divided into five groups: control (group 1, n = 6), radiocontrast media (group 2, n = 6), erdosteine (group 3, n = 7), erdosteine four doses before radiocontrast application (group 4, n = 7) and erdosteine one dose at the same day with radiocontrast application (group 5, n = 7). RIN was induced by administration of intravenous high osmolar contrast media amidotrizoate (6 mL/kg). Total RNA was extracted from the kidney, and the expression levels of Lipocalin 2 (Lcn2) and secreted phosphoprotein 1 (Spp1) genes were evaluated by real time reverse transcription polymerase chain reaction (real‐time RT‐PCR). Total antioxidant status (TAS) and total oxidant status (TOS) were measured in kidney homogenates and serum samples. Serum creatinine, BUN (Blood Urea Nitrogen) and cystatin‐C levels were measured from serum samples. The kidneys were evaluated histopathologically. The expression levels of Spp1 and Lcn2 genes in group 2 were significantly higher than groups 1, 3, 4, and 5. The expression levels of Spp1 and Lcn2 genes in group 4 were four and two times lower than group 5, respectively. Kidney TOS levels in group 2 were significantly higher than groups 1, 3, 4, and 5. Kidney TAS levels in group 3 were higher than group 2. Kidney oxidative stress index (OSI) levels in group 2 were significantly higher than groups 4 and 5. All rats in contrast media group developed tubular necrosis, proteinaceous casts, medullary congestion although these changes were significantly reduced in groups 4 and 5. This study demonstrated that multiple doses of erdosteine before application may have higher protective effects against RIN. © 2011 Wiley Periodicals, Inc. Environ Toxicol 2011.
Is Descartes a Materialist? The Descartes-More Controversy about the
Universe as Indefinite
Authors: Grobet Laura Benitez 
Published: March 2011

RÉSUMÉÀ travers l’étude de la
correspondance philosophique entre Descartes et Henry More, je souhaiterais
montrer que les thèmes centraux en sont la
considération de la nature de l’espace et le statut de
l’infini, bien que la polémique aborde
également le problème ontologique de la distinction
entre l’étendue et la pensée, et les
questions physiques de la négation du vide et de
l’atomisme. More rejette l’hypothèse
cartésienne d’un univers indéfini,
qu’il considère être une manière
détournée de postuler le caractère infini
de l’univers, ce qui revient à attribuer tout autant
l’infinité à la matière
qu’à Dieu, d’où le fait que
Descartes soit un matérialiste selon Henry More.
Biomasss and microzooplankton seasonal assemblages in the Bahía Blanca Estuary, Argentinean Coast
Authors: Barría de Cao M.S. , Piccolo M.C. , Perillo G.M. 
Published: March 2011

We investigated the occurrence and seasonal variation of the biomass of rotifers, tintinnids, the heterotrophic dinoflagellate Gyrodinium fusus and copepod nauplii in the Bahía Blanca Estuary (38°42′S61°50 ′W), Argentina, during an annual cycle. The rotifers fauna comprised three species, while the tintinnids were represented by sixteen species. The biomass of the rotifers fluctuated between 0.62 and 8.90 µgC l−1. The biomass of the tintinnids fluctuated between 0.13 and 9.37 µgC l−1, the biomass of the nauplii stages between 1.78 and 7.65 µgC l−1; while the biomass of G. fusus varied from 0.26 and 7.94 µgC l−1, these results are compared to estimates of microzooplankton in other regions. We analysed the presence of the different groups in relation to the environmental variables, based on point-biserial correlation. Salinity fluctuated between 25.14 and 36.64; temperature between 7.5 and 23.2°C, solar radiation between 0.9 and 30.8 MJ m−2d−1 and Secchi distance between 0.25 and 1.43 m. Rotifers were correlated positively with temperature, chlorophyll-a and Secchi depth and negatively with salinity. The tintinnids were positively correlated with salinity. Gyrodinium fusus was positively correlated with Secchi depth, and chlorophyll-a, and negatively with temperature and solar radiation. Nauplii stages were negatively correlated with chlorophyll-a. Based on the occurrence of the microzooplankters in relation to the physico-chemical variables, it was possible to establish two seasonal assemblages: (a) the co-occurrence of the rotifers and the heterotrophic dinoflagellate G. fusus during the winter–spring; and (b) the tintinnids and nauplii larvae during the summer. We conclude that, in this estuary, physico-chemical variables are the forcing factors that directly, or indirectly, influence the seasonal assemblages of the microzooplankton.
A new species of Paraseison (Rotifera: Seisonacea) from the coast of California, USA
Authors: Leasi Francesca , Rouse Greg W. , Sørensen Martin V. 
Published: March 2011

A new species of Paraseison (Rotifera: Seisonacea: Seisonidae) is described from the eastern Pacific Ocean off the coast of California. Female and male specimens of the new species were attached inside the carapace of the leptostracan crustacean Nebalia hessleri, collected at 19 m depth in La Jolla Canyon. This recording represents the first properly identified and described species of Seisonacea for the American coasts. It is furthermore the second known species of the genus Paraseison, which until now included the species P. annulatus only, reported for the Mediterranean Sea and European west Atlantic coast. The new species was diagnosed mostly by its species-specific trophi morphology and in particular by the shape of its fulcrum. Paraseison kisfaludyi sp. nov. is the fourth described species of the order Seisonacea, which accommodates also Seison nebaliae and the recently described S. africanus, all of which live attached to species in the leptostracan genus Nebalia. Even though the Seisonacea are placed in a crucial position within the phylum and may constitute the link between rotifers and other platyzoans, this taxon has in many respects been neglected in morphological studies. Herein we provide new information on the group's taxonomy, morphology and distribution, which will be useful for future phylogenetic and zoogeographical studies.
Noradrenergic-glucocorticoid modulation of emotional memory encoding in the human hippocampus
Authors: Kukolja J. , Klingmüller D. , Maier W. , Fink G. R. , Hurlemann R. 
Published: March 2011

BackgroundCurrent rodent models emphasize the joint action of the stress mediators noradrenaline (NE) and cortisol (CORT) in conferring a memory advantage of emotional over neutral stimuli.MethodUsing a pharmacological strategy of tackling this stress-related mechanism to enhance human episodic (autobiographical) memory, we measured amygdala-hippocampal responses during encoding of emotional and neutral stimuli with functional magnetic resonance imaging in 51 healthy subjects under four pharmacological conditions in a double-blind parallel group design: (i) placebo; (ii) the NE-reuptake inhibitor reboxetine (4 mg); (iii) hydrocortisone (synthetic CORT) (30 mg); or (iv) both agents in combination.ResultsDifferential drug effects were found in the left hippocampus, whereas hydrocortisone alone selectively decreased hippocampal responses to emotional relative to neutral stimuli, reboxetine potentiated hippocampal responses to these stimuli. Importantly, the inhibitory influence of hydrocortisone was reversed by co-administration of reboxetine.ConclusionsOur results imply that stress levels of CORT alone attenuate hippocampal responses to emotional stimuli, an effect possibly related to a regulatory negative feedback loop. However, when simultaneously elevated to stress levels, NE and CORT act together to synergistically enhance hippocampal activity during encoding of emotional stimuli, a mechanism that may turn maladaptive under circumstances of traumatic stress.