bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of the compatibilizer on the morphology and thermal properties of polypropylene‐layered double hydroxide composites
Authors: Coiai Serena , Passaglia Elisa , Hermann Alexandra , Augier Sylvain , Pratelli Daniele , Streller Rouven C. 
Published: March 2009

AbstractPolypropylene (PP)/layered double hydroxide (LDH) composites were prepared via melt‐compounding using both a carbonate‐LDH and an organo‐LDH (dodecyl benzene sulfonate DBS‐LDH) in different concentrations. Transmission electron microscopy and X‐ray diffraction analysis were used to investigate the morphology. The results showed that only by using DBS‐LDH the intercalation of polymer chains and a partial delamination were obtained. However, the introduction of maleic anhydride‐grafted polypropylene (PP‐g‐MAH), as coupling agent, favored the aggregation of the particles generating localized domains of aggregates. The thermo‐gravimetric analysis showed that PP/DBS‐LDH composites have a higher thermal stability than the pure matrix. Differential scanning calorimetry evidenced that both LDH and DBS‐LDH particles acted as nucleating agents increasing the crystallization temperature, even if, in the case of LDH the effect was observed only with the addition of the compatibilizer. The results collected by dynamic mechanical thermal analysis, beyond showing a significant increase of the matrix stiffness by incorporation of DBS‐LDH, evidenced an increase of the PP glass transition temperature (Tg) indicating a restriction of PP chain segment mobility due to the strong polymer‐particle interactions. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Proteomic analysis of the bacterial pathogen Bartonella henselae and identification of immunogenic proteins for serodiagnosis
Authors: Eberhardt Christian , Engelmann Susanne , Kusch Harald , Albrecht Dirk , Hecker Michael , Autenrieth Ingo B. , Kempf Volkhard A. J. 
Published: March 2009

AbstractBartonella henselae is a slow growing, fastidious and facultative intracellular pathogen causing cat scratch disease and vasculoproliferative disorders. To date, knowledge about the pathogenicity of this human pathogenic bacterium is limited and, additionally, serodiagnosis still needs further improvement. Here, we investigated the proteome of B. henselae using 2‐D SDS‐PAGE and MALDI‐TOF‐MS. We provide a comprehensive 2‐D proteome reference map of the whole cell lysate of B. henselae with 431 identified protein spots representing 191 different proteins of which 16 were formerly assigned as hypothetical proteins. To unravel immunoreactive antigens, we applied 2‐D SDS‐PAGE and subsequent immunoblotting using 33 sera of patients suffering from B. henselae infections. The analysis revealed 79 immunoreactive proteins of which 71 were identified. Setting a threshold of 20% seroreactivity, 11 proteins turned out to be immunodominant antigens potentially useful for an improved Bartonella‐specific serodiagnosis. Therefore, we provide for the first time (i) a comprehensive 2‐D proteome map of B. henselae for further proteome‐based studies focussed on the pathogenicity of B. henselae and (ii) an integrated view into the humoral immune responses targeted against this newly emerged human pathogenic bacterium.
Comparative proteomic profile of rat sciatic nerve and gastrocnemius muscle tissues in ageing by 2‐D DIGE
Authors: Capitanio Daniele , Vasso Michele , Fania Chiara , Moriggi Manuela , Viganò Agnese , Procacci Patrizia , Magnaghi Valerio , Gelfi Cecilia 
Published: March 2009

AbstractAgeing induces a progressive morphological change and functional decline in muscles and in nerves. Light and electron microscopy, 2‐D DIGE and MS, were applied to profile the qualitative and quantitative differences in the proteome and morphology of rat gastrocnemius muscle and sciatic nerve, in healthy 22‐month‐old rats. At muscle level, morphological changes are associated to fibre atrophy accompanied by myofibrillar loss and degeneration, disappearance of sarcomeres and sarcoplasmic reticulum dilatation, internal migration of nuclei, longitudinal fibre splitting, increment of subsarcolemmal mitochondria aggregates and increment of lipofuscin granules. Sciatic nerve shows myelin abnormalities like enfoldings, invaginations, onion bulbs, breakdowns and side axonal atrophy. Proteomic analysis identified changes correlated to morphological abnormalities in metabolic, contractile and cytoskeletal proteins, deregulation of iron homeostasis, change of Ca2+ balance and stress response proteins, accompanied by a deregulation of myelin membrane adhesion protein and proteins regulating the neuronal caliber. By comparing proteomic results from the two tissues, 16 protein isoforms showed the same up and down regulation trend suggesting that there are changes implying a general process which may act as a signal event of degeneration. Only β enolase and tropomyosin 1α were differentially expressed in the tissues.
High‐throughput screening of Erwinia chrysanthemi pectin methylesterase variants using carbohydrate microarrays
Authors: Øbro Jens , Sørensen Iben , Derkx Patrick , Madsen Christian T. , Drews Martin , Willer Martin , Mikkelsen Jørn D. , Willats William G. T. 
Published: March 2009

AbstractPectin methylesterases (PMEs) catalyse the removal of methyl esters from the homogalacturonan (HG) backbone domain of pectin, a ubiquitous polysaccharide in plant cell walls. The degree of methyl esterification (DE) impacts upon the functional properties of HG within cell walls and plants produce numerous PMEs that act upon HG in muro. Many microbial plant pathogens also produce PMEs, the activity of which renders HG more susceptible to cleavage by pectin lyase and polygalacturonase enzymes and hence aids cell wall degradation. We have developed a novel microarray‐based approach to investigate the activity of a series of variant enzymes based on the PME from the important pathogen Erwinia chrysanthemi. A library of 99 E. chrysanthemi PME mutants was created in which seven amino acids were altered by various different substitutions. Each mutant PME was incubated with a highly methyl esterified lime pectin substrate and, after digestion the enzyme/substrate mixtures were printed as microarrays. The loss of activity that resulted from certain mutations was detected by probing arrays with a mAb (JIM7) that preferentially binds to HG with a relatively high DE. Active PMEs therefore resulted in diminished JIM7 binding to the lime pectin substrate, whereas inactive PMEs did not. Our findings demonstrate the feasibility of our approach for rapidly testing the effects on PME activity of substituting a wide variety of amino acids at different positions.
A comprehensive Plasmodium falciparum protein interaction map reveals a distinct architecture of a core interactome
Authors: Wuchty Stefan , Adams John H. , Ferdig Michael T. 
Published: March 2009

AbstractWe derive a map of protein interactions in the parasite Plasmodium falciparum from conserved interactions in Saccharomyces cerevisiae, Caenorhabditis elegans, Drosophila melanogaster, and Escherichia coli and pool them with experimental interaction data. The application of a clique‐percolation algorithm allows us to find overlapping clusters, strongly correlated with yeast specific conserved protein complexes. Such clusters contain core activities that govern gene expression, largely dominated by components of protein production and degradation processes as well as RNA metabolism. A critical role of protein hubs in the interactome of P. falciparum is supported by their appearance in multiple clusters and the tendencies of their interactions to reach into many distinct protein clusters. Parasite proteins with a human ortholog tend to appear in single complexes. Annotating each protein with the stage where it is maximally expressed we observe a high level of cluster integrity in the ring stage. While we find no signal in the trophozoite phase, expression patterns are reversed in the schizont phase, implying a preponderance of parasite specific functions in this late, invasive schizont stage. As such, the inference of potential protein interactions and their analysis contributes to our understanding of the parasite, indicating basic pathways and processes as unique targets for therapeutic intervention.
Analysis of the periplasmic proteome of Pseudomonas aeruginosa, a metabolically versatile opportunistic pathogen
Authors: Imperi Francesco , Ciccosanti Fabiola , Perdomo Ariel Basulto , Tiburzi Federica , Mancone Carmine , Alonzi Tonino , Ascenzi Paolo , Piacentini Mauro , Visca Paolo , Fimia Gian Maria 
Published: March 2009

AbstractThe Gram‐negative bacterium Pseudomonas aeruginosa is a main cause of infection in hospitalized, burned, immunocompromised, and cystic fibrosis patients. Many processes essential for P. aeruginosa pathogenesis, e.g., nutrient uptake, antibiotic resistance, and virulence, take place in the cell envelope and depend on components residing in the periplasmic space. Recent high‐throughput studies focused on P. aeruginosa membrane compartments. However, the composition and dynamics of its periplasm remain largely uncharacterized. Here, we report a detailed description of the periplasmic proteome of the wild‐type P. aeruginosa strain PAO1 by 2‐DE and MALDI‐TOF/TOF analysis. Three extraction methods were compared at proteome level in order to achieve the most reliable and comprehensive periplasmic protein map. A total of 495 spots representing 395 different proteins were identified. Most of the high intensity spots corresponded to periplasmic proteins, while cytoplasmic contaminants were mainly detected among faint spots. The majority of the identified periplasmic proteins is involved in transport, cell‐envelope integrity, and protein folding control. Notably, more than 30% still has an unpredicted function. This work provides the first overview of the P. aeruginosa periplasm and offers the basis for future studies on periplasmic proteome changes occurring during P. aeruginosa adaptation to different environments and/or antibiotic treatments.
Properties modification of PET vascular prostheses
Authors: Chaouch W. , Dieval F. , Chakfe N. , Durand B. 
Published: March 2009

AbstractAging mechanisms have been investigated on polyethylene terephthalate (PET) fibres extracted from various vascular prostheses in order to identify the different modifications of the material's degradation. NMR spectroscopy provides a comprehensive view of chemical structures of macromolecules. Examination of a series of PET fibres showed significant chemical differences between the virgin prostheses and the explants, especially for diethylene glycol (DEG) and cyclic oligomeric groups. These analyses revealed that PET failures in vascular prostheses are susceptible to hydrolysis during in vivo stay. We also extended this 1H NMR technique to determine the hydroxyl and carboxyl end‐group concentrations. In order to validate the 1H NMR results, complementary techniques — chemical titration and classical viscosimetry — were used. The obtained results showed an increase in end‐group concentrations and a decrease of the viscosity averaged macromolecular weight (Mν) for the explants. Copyright © 2009 John Wiley & Sons, Ltd.
Role of sorption and degradation in the herbicidal function of isoxaflutole
Authors: Sims Gerald K , Taylor‐Lovell Sarah , Tarr Gabe , Maskel Shawn 
Published: March 2009

AbstractBACKGROUND: The fate of isoxaflutole (IFT) in soil is closely related to soil sorption. Sorption and transformation of IFT were investigated in laboratory incubations with four soils, and these results were used to interpret greenhouse studies using IFT to control several weed species.RESULTS: Degradation proceeded by previously observed pathways to form diketonitrile (DKN) and benzoic acid (BA) derivatives, as well as traces of unidentified products. Over the course of the incubation, DKN was the dominant active form of the herbicide present in the experimental system, and was thus critical to the soil activity of the herbicide for weed control.CONCLUSION: Control of most weed species appeared to be a function of both sorption and biodegradation of DKN, with greatest weed control being observed in soils in which a significant portion of the DKN that was formed persisted and remained bioavailable over the course of the incubation. Copyright © 2009 Society of Chemical Industry
New developments in green LEDs
Authors: Peter Matthias , Laubsch Ansgar , Bergbauer Werner , Meyer Tobias , Sabathil Matthias , Baur Johannes , Hahn Berthold 
Published: March 2009

AbstractGreen InGaN LEDs showed great improvements over the last decade, but still perform not as good as blue InGaN LEDs. Brightness, Efficiency and sub‐linearity of brightness versus driving current (“droop”) are significantly lower for a 530 nm green LED than for a 440 nm blue LED. Assuming an indirect Auger effect as one of the major loss mechanisms in InGaN LEDs, a reduction of the carrier density per emitting well is the key for efficiency improvement for green LEDs. An optimized multiple quantum well (MQW) structure with multiple emitting wells at 525 nm is compared to a single quantum well LED structure. A color‐coding scheme was used to investigate MQW operation: up to four MQWs contribute to the green emission at 525 nm. Packaged 1 × 1 mm2 ThinGaN® chips emit up to 109 lm (209 mW) at 350 mA and 170 lm (339 mW) at 700 mA, the efficacy was 90 lm/W and 66 lm/W, respectively. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modulation spectroscopy of InAs semiconductor nanostructures grown on (631) high index substrates
Authors: Méndez‐García Victor H. , Martínez‐Velis I. , Rojas‐Ramirez J. S. , Contreras‐Guerrero R. , Ramírez‐Lopez M. , Hernandez‐Rosas J. , Garcia‐Liñan G. , Gorbatchev A. Yu. , Zamora‐Peredo L. , López‐López M. 
Published: March 2009

AbstractThe molecular beam epitaxial (MBE) growth of InAs nanostructures on GaAs(631)‐oriented substrates is studied by photoluminescence (PL) and photoreflectance spectroscopy (PR). First, a corrugated surface conformed by regularly spaced grooves aligned along the [$ \bar 5 $93] azimuth was formed by the GaAs homoepitaxial growth on the (631) substrate. On this template, we proceeded with the deposition of InAs at several thicknesses in the range of 1 to 4.5 monolayers (MLs). An atomic force microscopy (AFM) analysis of samples without GaAs capping, revealed that assemblage of QDs occurs only after the deposition of the equivalent to ∼1.9 ML of InAs. On these samples, we observed changes on the PR line‐shape in the near‐bandgap GaAs region linked to the quantity of InAs deposited. The intensity of the built in electric fields was correlated with the strain state at the heterointerface, as a consequence of the self induced piezoelectric effect, typical from high index surfaces. On the other hand, when the samples were capped with a 100 Å thick GaAs layer, strong emission of the nanostructures occurs even for deposited quantities of InAs as low as 1 ML. Since for this InAs thickness the self‐assemblage of QDs is not observed, the optical transitions observed were associated with the optical emission of self assembled semiconductor quantum wires, promoted by surface diffusion anisotropy, characteristic of the (631) plane. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multi‐decker sandwich complexes using Be32− and Mg32− dianions
Authors: Chattaraj P. K. , Giri S. 
Published: March 2009

AbstractGlobal and local reactivity descriptors as well as the nucleus independent chemical shift values of different multi‐decker sandwich complexes involving Be32− and Mg32− dianions are calculated at the B3LYP/6‐311+G* level of theory. Important insights into their bonding, reactivity, and aromaticity are obtained through this study. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Transferability of the venture capital model to the corporate context: Implications for the performance of corporate venture units
Authors: Hill Susan A. , Maula Markku V. J. , Birkinshaw Julian M. , Murray Gordon C. 
Published: March 2009

AbstractWhile recent literature has advocated the transfer of venture capital (VC) practices and structures to corporate venture (CV) units, the wisdom of this advice has not been subject to rigorous empirical scrutiny. We test the implications of the VC model for CV unit performance using a longitudinal database combining survey, archival, and survival data on 95 CV units. VC model elements of high‐powered incentives, autonomous organization, investment syndication, investment staging, and specialization were each associated with higher CV unit performance. Critically, different elements of the VC model predicted improvements in either strategic or financial performance in CV units. Survival of the CV unit was strongly associated with employing the VC model, partially mediated by enhanced performance. Copyright © 2009 Strategic Management Society.
Self‐selection, endogeneity, and the relationship between CEO duality and firm performance
Authors: Iyengar Raghavan J. , Zampelli Ernest M. 
Published: March 2009

AbstractThis study focuses explicitly on the methodological implications of the endogenous theory of governance as applied to firm performance. In particular, if firms choose their governance structures as part of a constrained performance maximization process, then application of an appropriate empirical methodology should reveal statistical evidence of such behavior. In this study we take advantage of the endogenous switching regression model framework to determine whether such predicted optimizing behavior can be corroborated by the data. The model allows us to test explicitly for selection behavior in accordance with comparative advantage and, concomitantly, the presence of selectivity bias, in estimating the impact of CEO duality on firm performance. The selection and performance equations are modeled in accordance with the extant accounting, economics, and management literature on the impact of the dual governance structure on firm performance. Overall, we tested four performance measures for the entire sample of firm‐year observations as well as for the largest three industries in terms of sample sizes. The major finding, robust in all cases, is that there is no evidence to support a contention that CEO duality is a structure purposefully chosen for optimizing performance. If firms are indeed choosing the dual leadership structure, they are doing so for reasons other than improving performance from what it would be otherwise. In fact, for performance measured as market return and earnings per share, there is evidence of a significant selectivity bias that acts to lower performance below what it would have been under random assignment. For performance measured by Tobin's q and return on assets, we found neither evidence of selectivity bias, nor any significant marginal performance impacts of CEO duality. Such findings are inconsistent with an endogenous governance theory, at least when applied to firm performance. Copyright © 2009 John Wiley & Sons, Ltd.
A novel wideband space‐time channel simulator based on the geometrical one‐ring model with applications in MIMO‐OFDM systems
Authors: Zhang Haixia , Yuan Dongfeng , Pätzold Matthias , Wu Yi , Nguyen Van Duc 
Published: March 2009

AbstractIn this paper, we extend the geometrical one‐ring multiple‐input multiple‐output (MIMO) channel model with respect to frequency selectivity. Our approach enables the design of efficient and accurate simulation models for wideband space‐time MIMO channels under isotropic scattering conditions. Two methods will be provided to compute the parameters of the simulation model. Especially, the temporal, frequency and spatial correlation properties of the proposed wideband space‐time MIMO channel simulator are studied analytically. It is shown that any given specified or measured discrete power delay profile (PDP) can be incorporated into the simulation model. The high accuracy of the simulation model is demonstrated by comparing its statistical properties with those of the underlying reference model with specified correlation properties in the time, frequency and spatial domain. As an application example of the new MIMO frequency‐selective fading channel model, we study the influence of various channel model parameters on the system performance of a space‐time coded orthogonal frequency division multiplexing (OFDM) system. For example, we investigate the influence of the antenna element spacings of the base station (BS) antenna as well as the mobile station (MS) antenna. It turns out that an increasing of the antenna element spacing at the BS side results in a higher diversity gain than an increasing of the antenna element spacing at the MS side. Furthermore, the diversity gain brought in by space‐time block coding schemes is investigated by simulation. Our results show that transmitter diversity can significantly reduce the symbol error rate (SER) of multiple antenna systems. Finally, the influence of the Doppler effect and the impact of imperfect channel state information (CSI) on the system performance is also investigated. Copyright © 2009 John Wiley & Sons, Ltd.
Sustainability of gains made in a primary school HIV prevention programme in Kenya into the secondary school years
Authors: Maticka‐Tyndale Eleanor 
Published: March 2009

ABSTRACTThe question addressed in this paper is whether the beneficial effects of Primary School Action for Better Health (PSABH), an HIV prevention programme delivered in Kenyan primary schools, continue once students move on to secondary schools. Questionnaires were completed in December 2005 and January 2006 by all form 1–3 students in 154 randomly selected secondary schools. Students who had attended primary schools with PSABH programming were compared to those who did not on knowledge, attitudes and behaviours using multivariate regression with controls for gender, school year, religion and financial resources. Students who attended PSABH primary schools were significantly more likely to have higher levels of knowledge and attitudes that were more supportive of sexual restraint, condom use and HIV testing. They were more likely to have used several safer sex practices and to have been tested for HIV. The effects were strongest in the first year of secondary school and decreased thereafter. PSABH continues to have a beneficial effect for students who continue to secondary school.
Oil and gas pools: the fundamentals of formation, prospecting, and exploitation
Authors: Nesterov I.I. 
Published: March 2009

Abstract
The paper deals with the main fundamental problem of oil and gas geology—compilation of a theoretical basis and elucidation of the mechanism of hydrocarbon pool formation. The temperature factor determining this mechanism is insufficient for the breaking of carbon–carbon bonds in organic molecules. It is shown that this process is provoked by the internal energy of the subsurface organic matter determined by unpaired electrons surrounding carbon nuclei. In natural processes, this phenomenon is realized as a result of sedimentary-rock consolidation on the subsidence of sedimentation basins, during subhorizontal microdislocations measured via Poisson’s ratio and Protod’yakonov “arch”. This effect can be reached on hydrofracturing. A possibility of fluid hydrocarbon migration beyond the modern-day oil and gas pools is discussed, thus demonstrating that there are no traces that would suggest oil migration. Hydrocarbon pools have been revealed in clayey rocks, both bituminous and OM-poor. It is shown that the exploitation of a new type of reservoir (bazhenite) with natural hydrocarbon pools as well as technogenic (newly formed) oil and gas pools in clayey, clay-siliceous, siliceous, clay-carbonate, and clay-siliceous-carbonate bituminous rocks will significantly increase oil production in West Siberia.