bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure and thermostability of PMMA in PMMA/silica nanocomposites: Effect of high‐energy ball milling and the amount of the nanofiller
Authors: Pantaleón Ruben , González‐Benito Javier 
Published: December 2009

AbstractIn this work, the effect of the presence of silica nanoparticles in the structure, dynamics, and thermodegradation of poly(methyl methacrylate), PMMA, has been considered. A new method for preparing nanocomposites has been considered in which high‐energy ball milling, HEBM, was used to uniformly disperse nanoparticles within a polymeric matrix (PMMA). Fourier transform infrared spectroscopy, FTIR, was used to analyze the structure and dynamics of the PMMA to study the influence of the presence of silica nanoparticles and finally to discuss the thermal stability of these nanocomposites. Dynamic thermogravimetric analyses were performed to carry out the kinetics analysis about the thermostability of the modified PMMA, being the milling process and the amount of nanoparticles the variables taken into account. The milling process creates chain ends on the PMMA favoring its first step of thermal degradation. There is only an improvement in terms of thermal stability if the amount of silica nanoparticles within the PMMA exceeds a threshold higher than 2% by weight when the unfavorable effect of the milling process is compensated. POLYM. COMPOS., 31:1585–1592, 2010. © 2009 Society of Plastics Engineers
Comparison of the effectiveness and efficiency of oral and written retellings and passage review as strategies for comprehending text
Authors: Schisler Rebecca , Joseph Laurice M. , Konrad Moira , Alber‐Morgan Sheila 
Published: December 2009

AbstractThe purpose of this study was to compare the instructional effectiveness and efficiency of oral retelling, written retelling, and passage review comprehension strategies on third‐grade students' accuracy and rate of answering reading comprehension questions. A modified alternating treatment design was used to compare the effects of oral retelling, written retelling, and passage review strategies. Each strategy occurred within the context of repeated readings with phrase drill error correction. This study extended previous research findings by examining the effects of oral and written retelling as strategies for improving both literal and inferential comprehension and by investigating the efficiency of retelling procedures. Findings revealed that students' accuracy in answering reading comprehension performance was better under both retelling conditions than the passage review condition. The oral retelling coupled with repeated readings and phrase drill error correction was the most efficient instructional method for answering comprehension questions correctly. © 2009 Wiley Periodicals, Inc.
Applied comparative effectiveness researchers must measure learning rates: A commentary on efficiency articles
Authors: Skinner Christopher H. 
Published: December 2009

AbstractAlmost all academic skills deficits can be conceptualized as learning rate problems as students are not failing to learn, but not learning rapidly enough. Thus, when selecting among various possible remedial procedures, educators need an evidence base that indicates which procedure results in the greatest increases in learning rates. Previous research is reviewed that shows how failure to measure learning rates can lead to erroneous conclusions regarding the relative effectiveness of interventions. Different procedures for measuring learning rates are described and cautions regarding the interpretation of these learning rate data are provided. The article concludes with a plea for all researchers to include measures of learning rates in their applied studies. © 2009 Wiley Periodicals, Inc.
Evaluation of a truancy court intervention in four middle schools
Authors: Hendricks Michelle A. , Sale Elizabeth W. , Evans Carol J. , McKinley Lori , DeLozier Carter Sherri 
Published: December 2009

AbstractThe effectiveness of a school‐based truancy court intervention in four middle schools in a mid‐sized school district was evaluated. Cumulative data from 185 youth attending a truancy court from 2004 through 2008 were included in the analyses. Results indicated a differential impact of the truancy court intervention depending on truancy severity at baseline. The intervention was most successful in increasing attendance for students with severe truancy, but had limited impact on students with moderate truancy, and no impact on mild truancy. The intervention did not result in improved school attachment or grade point averages, nor did it significantly reduce discipline offenses. Furthermore, the aftercare intervention, consisting of regular meetings with an authority figure (e.g., a juvenile officer), was only effective at maintaining truancy court attendance gains for students with severe truancy at baseline, although it was associated with a substantial decrease in discipline offenses for all groups. These results suggest that truancy courts similar to the one described here may have an impact on truancy for severely truant students, but may have a limited effect on students with mild or moderate truancy. © 2009 Wiley Periodicals, Inc.
Farbbilder aus gefrorenem Licht. Interferentielle Fotografie
Authors: Kellerbauer Alban 
Published: December 2009

AbstractVor über hundert Jahren entwickelte Gabriel Lippmann die Heliochromie. Dieses fotografische Verfahren kann das kontinuierliche Spektrum des sichtbaren Lichts abbilden. Dabei speichert die Fotoemulsion in ihrem Volumen die Farbinformation als Fourier‐Transformierte des ursprünglichen Spektrums. Moderne holografische Techniken funktionieren ähnlich, halten aber statt der Wellenlänge des reflektierten Lichts seine Phase und damit die dreidimensionale Gestalt des Objekts fest. Aus technischen und wirtschaftlichen Gründen konnte sich die Heliochromie nicht durchsetzen. Neue spektrometrische Verfahren zum Beispiel nutzen jedoch wieder das Prinzip der Lippmannschen Fotografie.
Flüsse, Seen und Dünen auf dem Titan
Authors: Langhans Mirjam 
Published: December 2009

AbstractNeue Radardaten der Cassini‐Sonde enthüllen erdähnliche Landschaften auf dem Titan, dem größten Mond des Saturn. Die Bilddaten zeigen Täler und Flussläufe, wie sie auch für die Oberfläche der Erde typisch sind. Allerdings werden oder wurden sie auf dem Titan von flüssigem Methan geformt.
Röntgenstrahlung mit einem Laserplasma‐Beschleuniger
Authors: Fuchs Matthias , Grüner Florian 
Published: December 2009

AbstractUnserem Team des Labors für Attosekundenphysik der Ludwig‐Maximilians‐Universität München und des Max‐Planck‐Instituts für Quantenoptik in Garching ist es erstmals gelungen, Röntgenquellen, die normalerweise mehrere Kilometer groß sind, auf die Größe eines Tisches zu verkleinern. Hierfür nutzen wir eine neue Methode, basierend auf Laserpulsen mit ultrahohen Intensitäten, einem Wasserstoffplasma und einem Undulator.
Perfekte Abbildung in neuem Licht
Authors: Leonhardt Ulf 
Published: December 2009

AbstractSelbst mit dem stärksten optischen Mikroskop kann man keine Nanostrukturen, Moleküle oder gar Atome sehen. Für Nanostrukturen benötigt man ein Elektronenmikroskop, oder man tastet sie per Nahfeldmikroskopie mühsam ab. Neue theoretische Berechnungen legen aber nahe, dass man durch integrierte Optik ein unbegrenztes Auflösungsvermögen erzielen kann.
Tricks aus der Schatzkammer der Physik
Authors: Rolfs Claus 
Published: December 2009

AbstractWeit mehr als drei Millionen verschiedene Arten an Pflanzen und Tieren bevölkern die Erde. Diese enorme Vielfalt ist das Ergebnis der Evolution. Sie kam immer dann einen Schritt voran, wenn eine neue Erfindung stattfand, wenn die Lebewesen also einen neuen Trick aus der Schatzkammer der Physik entdeckten. Dazu zählen die Konvektion im Transport von Energie und Nahrung, Nervenbahnen für Signale zum Gehirn, Isolierung des Körpers, Sehen und Erkennen mit Augen oder Empfang und Aussenden von Schallwellen. In dieser neuen Serie zeigen wir, wie physikalische Gesetze Verhalten und Entwicklung der Lebewesen bestimmen und Grenzen in der Biosphäre ziehen.
Nanokristalline Metalle. Neue Werkstoffe aus plastischer Hochverformung
Authors: Pippan Reinhard , Hohenwarter Anton , Scheriau Stephan , Bachmaier Andrea 
Published: December 2009

AbstractNanokristalline metallische Materialien zeichnen sich durch hohe mechanische Festigkeit aus. Über die Größe der Körner (Kristallite) sind auch ihre magnetischen Eigenschaften sehr variabel einstellbar. Eine Möglichkeit, sie herzustellen, ist die Hochverformung. Ausgangspunkt ist ein herkömmliches Material mit Korngrößen im Mikro‐ bis Millimeterbereich. Unter hohem Druck wird es bei relativ niedrigen Temperaturen plastisch verformt, bis es nanokristallin wird. Diese Umwandlung geschieht durch den Einbau von Kristallbaufehlern und die Bildung von zellartigen Strukturen aus diesen Fehlern. Die Zellwände bilden dann die Grenzen zwischen den neuen Kristalliten. Mit zunehmender Verformung sinkt die Größe der Kristallite bis zu einem Sättigungszustand. Diese minimale Kristallitgröße hängt unter anderem von der Verformungstemperatur und dem Legierungsgehalt ab.
Bereavement care: some clinical observations
Authors: Greer Steven 
Published: December 2009

AbstractThe needs of cancer patients' bereaved carers require attention. Although the majority of bereaved individuals manage to cope with their loss, a minority remain distressed and suffer serious prolonged disruption of their lives. The Yale Bereavement Study has revealed a specific syndrome, prolonged grief disorder. The diagnostic criteria of this disorder are outlined and several clinical illustrations are presented. Preliminary evidence suggests that cognitive‐behaviour therapy (CBT) can be effective in the management of prolonged grief disorder. An example of the use of CBT is provided together with some useful clinical guidelines. Copyright © 2009 John Wiley & Sons, Ltd.
A novel defensin‐like peptide from salivary glands of the hard tick, Haemaphysalis longicornis
Authors: Lu Xiangyun , Che Qiaolin , Lv Yi , Wang Meijuan , Lu Zekuan , Feng Feifei , Liu Jingze , Yu Haining 
Published: December 2009

AbstractA novel defensin‐like antimicrobial peptide named longicornsin was isolated from the salivary glands of the hard tick, Haemaphysalis longicornis, using a 10‐kDa cut‐off Centriprep filter and reversed‐phase high‐performance liquid chromatography (RP‐HPLC). Its amino acid sequence was determined as DFGCGQGMIFMCQRRCMRLYPGSTGFCRGFRCMCDTHIPLRPPFMVG by Edman degradation. The cDNA encoding longicornsin was cloned by cDNA library screening. The predicted protein from the cDNA sequence was composed of 78 amino acids including a mature longicornsin. It showed similarity with defensin‐like peptides from other ticks by BLAST search. Different from most other tick defensin‐like peptides, longicornsin had a C‐terminal extension. Purified longicornsin exerted potent antimicrobial activities against bacteria and fungi. Interestingly, it even showed strong antimicrobial ability against drug‐resistant microorganisms and Helicobacter pylori. The results of this study indicated that longicornsin is a potential candidate for novel antimicrobial drug design.
Association of CASP8 D302H polymorphism with reduced risk of aggressive prostate carcinoma
Authors: Lubahn Jessica , Berndt Sonja I. , Jin Carol H. , Klim Aleksandra , Luly Jason , Wu William S. , Isaacs Sarah , Wiley Kathleen , Isaacs William B. , Suarez Brian K. , Hayes Richard B. , Kibel Adam S. 
Published: December 2009

AbstractBACKGROUNDBecause of the dramatically different clinical course of aggressive and indolent prostate carcinoma (PCa), markers that distinguish between these phenotypes are of critical importance. Apoptosis is an important protective mechanism for unrestrained cellular growth and metastasis. Therefore, dysfunction in this pathway is a key step in cancer progression. As such, genetic variants in apoptosis genes are potential markers of aggressive PCa. Recent work in breast carcinoma has implicated the histidine variant of CASP8 D302H (rs1045485) as a protective risk allele.METHODSWe tested the hypothesis that the H variant was protective for aggressive PCa in a pooled analysis of 796 aggressive cases and 2,060 controls.RESULTSThe H allele was associated with a reduced risk of aggressive PCa (ORper allele = 0.67, 95% CI: 0.54–0.83, Ptrend = 0.0003). The results were similar for European‐Americans (ORper allele = 0.68; 95% CI: 0.54–0.86) and African‐Americans (ORper allele = 0.61; 95% CI: 0.34–1.10). We further determined from the full series of 1,160 cases and 1,166 controls in the Prostate, Lung, Colorectal, Ovarian (PLCO) population that the protective effect of the H allele tended to be limited to high‐grade and advanced PCa (all cases ORper allele = 0.94; 95% CI: 0.79–1.11; localized, low‐grade disease ORper allele = 0.98; 95% CI: 0.79–1.23; and aggressive disease ORper allele = 0.73; 95% CI: 0.50–1.07).CONCLUSIONThese results suggest that histidine variant of CASP8 D302H is a protective allele for aggressive PCa with potential utility for identification of patients at differential risk for this clinically significant phenotype. Prostate 70: 646–653, 2010. © 2009 Wiley‐Liss, Inc.
Feature space resampling for protein conformational search
Authors: Blum Ben , Jordan Michael I. , Baker David 
Published: December 2009

AbstractDe novoprotein structure prediction requires location of the lowest energy state of the polypeptide chain among a vast set of possible conformations. Powerful approaches include conformational space annealing, in which search progressively focuses on the most promising regions of conformational space, and genetic algorithms, in which features of the best conformations thus far identified are recombined. We describe a new approach that combines the strengths of these two approaches. Protein conformations are projected onto a discrete feature space which includes backbone torsion angles, secondary structure, and beta pairings. For each of these there is one “native” value: the one found in the native structure. We begin with a large number of conformations generated in independent Monte Carlo structure prediction trajectories from Rosetta. Native values for each feature are predicted from the frequencies of feature value occurrences and the energy distribution in conformations containing them. A second round of structure prediction trajectories are then guided by the predicted native feature distributions. We show that native features can be predicted at much higher than background rates, and that using the predicted feature distributions improves structure prediction in a benchmark of 28 proteins. The advantages of our approach are that features from many different input structures can be combined simultaneously without producing atomic clashes or otherwise physically inviable models, and that the features being recombined have a relatively high chance of being correct. Proteins 2010. © 2009 Wiley‐Liss, Inc.
Crystal structure and oligomeric state of the RetS signaling kinase sensory domain
Authors: Jing Xing , Jaw Jessica , Robinson Howard H. , Schubot Florian David 
Published: December 2009

AbstractThe opportunistic pathogen Pseudomonas aeruginosa may cause both acute and chronic‐persistent infections in predisposed individuals. Acute infections require the presence of a functional type III secretion system (T3SS), whereas chronic P. aeruginosa infections are characterized by the formation of drug‐resistant biofilms. The T3SS and biofilm formation are reciprocally regulated by the signaling kinases LadS, RetS, and GacS. RetS downregulates biofilm formation and upregulates expression of the T3SS through a unique mechanism. RetS forms a heterodimeric complex with GacS and thus prevents GacS autophosphorylation and downstream signaling. The signals that regulate RetS are not known but RetS possesses a distinctive periplasmic sensor domain that is believed to serve as receptor for the regulatory ligand. We have determined the crystal structure of the RetS sensory domain at 2.0 Å resolution. The structure closely resembles those of carbohydrate binding modules of other proteins, suggesting that the elusive ligands are likely carbohydrate moieties. In addition to the conserved beta‐sandwich structure, the sensory domain features two alpha helices which create a unique surface topology. Protein–protein crosslinking and fluorescence energy transfer experiments also revealed that the sensory domain dimerizes with a dissociation constant of Kd = 580 ± 50 nM, a result with interesting implications for our understanding of the underlying signaling mechanism. Proteins 2010. © 2009 Wiley‐Liss, Inc.
Thermodynamics of the Trp‐cage miniprotein unfolding in urea
Authors: Wafer Lucas N. R. , Streicher Werner W. , Makhatadze George I. 
Published: December 2009

AbstractThe thermodynamic properties of unfolding of the Trp‐cage mini protein in the presence of various concentrations of urea have been characterized using temperature‐induced unfolding monitored by far‐UV circular dichroism spectroscopy. Analysis of the data using a two‐state model allowed the calculation of the Gibbs energy of unfolding at 25°C as a function of urea concentration. This in turn was analyzed by the linear extrapolation model that yielded the dependence of Gibbs energy on urea concentration, i.e. the m‐value for Trp‐cage unfolding. The m‐value obtained from the experimental data, as well as the experimental heat capacity change upon unfolding, were correlated with the structural parameters derived from the three dimensional structure of Trp‐cage. It is shown that the m‐value can be predicted well using a transfer model, while the heat capacity changes are in very good agreement with the empirical models based on model compounds studies. These results provide direct evidence that Trp‐cage, despite its small size, is an excellent model for studies of protein unfolding and provide thermodynamic data that can be used to compare with atomistic computer simulations. Proteins 2010. © 2009 Wiley‐Liss, Inc.
p‐Coumaric acid decarboxylase from Lactobacillus plantarum: Structural insights into the active site and decarboxylation catalytic mechanism
Authors: Rodríguez Héctor , Angulo Iván , de las Rivas Blanca , Campillo Nuria , Páez Juan A. , Muñoz Rosario , Mancheño José M. 
Published: December 2009

Abstractp‐Coumaric acid decarboxylases (PDCs) catalyze the nonoxidative decarboxylation of hydroxycinnamic acids to generate the corresponding vinyl derivatives. Despite the biotechnological relevance of PDCs in food industry, their catalytic mechanism remains largely unknown. Here, we report insights into the structural basis of catalysis for the homodimeric PDC from Lactobacillus plantarum (LpPDC). The global fold of LpPDC is based on a flattened β‐barrel surrounding an internal cavity. Crystallographic and functional analyses of single‐point mutants of residues located within this cavity have permitted identifying a potential substrate‐binding pocket and also to provide structural evidences for rearrangements of surface loops so that they can modulate the accessibility to the active site. Finally, combination of the structural and functional data with in silico results enables us to propose a two‐step catalytic mechanism for decarboxylation of p‐coumaric acid by PDCs where Glu71 is involved in proton transfer, and Tyr18 and Tyr20 are involved in the proper substrate orientation and in the release of the CO2 product. Proteins 2010. © 2009 Wiley‐Liss, Inc.
The dynamics of vented gas explosions
Authors: Proust Ch. , Leprette E. 
Published: December 2009

AbstractThe results of a large test series on vented gas explosions are herein reported (with vessel sizes ranging from 1 to 100 m3 mixture of methane, propane, and hydrogen with air). The pressure was not only measured internally but also externally. The flame propagation was also recorded with a speed camera. It is shown that a very significant explosion could result from the formation and ignition of the combustible cloud outside the vent and that, in a number of circumstances, this “external” explosion would overcome the internal one. Surprising results were also obtained showing, for instance, that near the vent the maximum overpressure may be lower than further downstream. This is not because the external explosion is developing far downstream but because of the local influence of the chamber pumping the outside atmosphere after the flame went out (thus creating a lower than atmosphere pressure) produced at the vent. The mode of combustion of the external cloud is still outstanding and cannot be described by the traditional outward expanding flame kernel. © 2009 American Institute of Chemical Engineers Process Saf Prog, 2010
Explosion characteristics of hydrogen‐air mixtures in a spherical vessel
Authors: Jo Young‐Do , Crowl Daniel A. 
Published: December 2009

AbstractHydrogen has been proposed as a potential fuel to replace fossil fuels and to reduce carbon emissions. This paper presents experimental data on the explosion characteristics of hydrogen‐air mixtures in a 20‐L sphere. This includes the maximum explosion pressure, deflagration index, the exponent parameter of the burning velocity, and the burning parameter. Methods and equations are provided to estimate these parameters.The experimental maximum explosion pressure agrees with the theoretical value estimated using a chemical equilibrium program if the concentration of hydrogen is from 10 to 75% in air, but not close to the flammable limits. Therefore, the maximum pressure can be estimated conservatively by the equilibrium program regardless of the size of the explosion vessel.The deflagration index for hydrogen‐air mixtures, even if normalized by the cube root of the volume of explosion vessel, is found to be sensitive to the vessel volume. The maximum deflagration index in our 20‐L explosion vessel is measured as 970 bar‐m/sec at 36 vol. % of hydrogen in air. Other investigators have shown that it increases with the volume of the explosion vessel.We propose a theoretical model to estimate the deflagration index. This model shows that the experimentally determined value depends highly on the fraction of burnt gas just before the flame contacts the vessel wall. This model can be used to estimate a maximum deflagration index assuming the flame propagates to and arrives at the vessel wall at the same time without any previous quenching. The deflagration index estimated using this approach has a value as high as 1,700 bar‐m/sec.The apparent burning velocity increases as the pressure increases during the explosion. The exponent parameter is a constant to correlate the variation of the apparent burning velocity with the change in pressure during the explosion, which we determined to be about 0.45 for hydrogen‐air mixtures.A burning parameter was also calculated from our experimental data. The burning parameter is directly related to the laminar burning velocity of the gas mixture and the wrinkling of the flame front. It is a single kinetic parameter that can be used with a flame growth model to calculate the pressure‐time history from initial ignition up to the maximum explosion pressure. An empirical equation for the burning parameter for hydrogen‐air mixtures is developed from this work. The maximum value of the burning parameter occurs at about 40 vol. % of hydrogen in air, which is above the stoichiometric concentration of 29.6 vol. %.The proposed equations and methods for estimating the maximum explosion pressure, burning parameter, and deflagration index will be useful for safely using hydrogen to prevent catastrophic accidents in the application of hydrogen gas. © 2009 American Institute of Chemical Engineers Process Saf Prog, 2010