bluuebunny/crossref_metadata_2025_split huggingface dataset:
A comparative study of dispersing a polyamide 6 into a polypropylene melt in a Buss Kneader, continuous mixer, and modular intermeshing corotating and counter‐rotating twin screw extruders
Authors: Shon Keungjin , Bumm Sug Hun , White James L. 
Published: February 2008

AbstractWe have made a study of the development of phase morphology of an immiscible blend(75/25)(polypropylene–polyamide‐6) for different types of continuous mixers including (i) Buss Kneader, (ii and iii) modular intermeshing corotating and counter‐rotating twin screw extruders, and (iv) NEX‐T Kobelco Continuous Mixer. Comparisons are made using different screw configurations for each machine. Generally, in comparison of the different machines, the intermeshing counter‐rotating twin screw extruder produced the finest dispersed morphology. Using a droplet breakup kinetic model, we interpreted the blend dispersed phase droplet breakdown rate and coalescence rate. In comparison with our earlier study of the continuous mixing of agglomerates of CaCO3 particles the polymer droplet breakup rate was smaller than that of the particle agglomerates and the coalescence rates of droplets were many times greater than the particle reagglomerates rates. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Calculation and significance of the maximum polymer surface temperature T* in reciprocating cylinder‐on‐plate sliding
Authors: Samyn Pieter , Schoukens Gustaaf 
Published: February 2008

AbstractHeat generation and surface temperature rise are the main parameters controlling friction and wear of polymers, while certain transitions in sliding behavior often are difficultly related to intrinsic polymer transition temperatures. The sliding temperature cannot be accurately measured through physical limitations in the contact interface, and different calculation methods are available. Some temperature models are reviewed and applied to the reciprocating sliding of polyimide (PI) and polyethylene terephthalate against a steel counterface. The bulk temperature and asperity flash temperature models cannot explain transitions in friction and wear for polymers under reciprocating sliding. The bulk temperature model provides too low temperatures, representing a long‐range temperature, while the asperity flash temperature model provides too high temperatures, not considering visco‐elastic deformation of the polymer surface. An experimental model for the maximum polymer surface temperature T* under reciprocating sliding is developed, considering the environmental temperature, gradual heating of the steel counterface, and additional heating of the polymer surface. The proposed temperature model is analytically validated by differential thermal analysis and thermogravimetric analysis. Transitions in tribological behavior are controlled by the maximum polymer surface temperature T*, coinciding with an endotherm reaction (PIs) or a glass transition and melting (polyethylene terephthalate). POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
In‐line measurements of the morphological parameters of PP/PA6 blends during extrusion in the transient mode
Authors: Pinheiro Luís A. , Hu Guo‐H. , Pessan Luiz A. , Canevarolo Sebastião V. 
Published: February 2008

AbstractThe real‐time measurement of the morphology of immiscible polymer blends based on polypropylene (PP) and polyamide 6 (PA6) was performed during melt blending in a twin‐screw extruder. The disperse phase particle size and concentration were obtained in‐line with an optical device placed at the die exit. To validate the response of the optical device, its detector was calibrated in advance in a bench using ceramic particles of well‐controlled size dispersed in water. The optical device was able to measure the changes in particle size and concentration and the data enabled the calculation of the particle extinction cross section. Melt blending experiments in the extruder were performed in a transient mode, where a small amount of the material was added as a pulse to the main melt flow. The pulses containing pellets of the PA6 and polypropylene grafted with acrylic acid (PP‐g‐AA) were added to the PP flow stream in different amounts. The detector's response increased with increasing concentrations in the PA6 and PP‐g‐AA. The disperse phase particle size decreased concomitantly because of the compatibilizing effect of the PP‐g‐AA on the PP/PA6 immiscible blend. That observation confirmed that the detector's response was directly related to the disperse phase particle size. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Das Rijke‐Rohr. Physikdidaktik
Authors: Bergeler Elmar 
Published: February 2008

AbstractDas Rijke‐Rohr ist ein eindrucksvolles Freihandexperiment zur Veranschaulichung akustischer Resonatoren. Es besteht aus einem Glasrohr, in dessen unterer Hälfte ein Metallsieb angebracht ist. Wird dieses erhitzt und von der Flamme entfernt, so ertönt ein lautstarkes Orgelpfeifen. Ursache ist die Übertragung von thermischer Energie auf die sich in dem Rohr befindende Luft. Diese wird unter bestimmten Voraussetzungen zu akustisch wahrnehmbaren Schwingungen angeregt. Die Frequenzen der Schwingungen sind durch die Eigenfrequenzen der eingeschlossenen Luftsäule gegeben.
Quantenpunkte als Photonenquellen. Photonische Kristalle
Authors: Stumpf Wolfgang 
Published: February 2008

AbstractQuantenpunkte in Nanoresonatoren sind Lichtquellen mit bestechenden Eigenschaften. Sie können als winzige Laser arbeiten, deren Laserschwelle extrem niedrig liegt. Nanoresonatoren und andere Licht leitende und steuernde Bauelemente lassen sich über photonische Kristalle realisieren. Quantenpunkte in Nanoresonatoren bieten der optischen Kommunikationstechnik eine interessante Zukunftsperspektive. Sie könnten eine extrem schnelle Schnittstelle zwischen optischer Datenübertragung und Elektronik bilden. Zudem könnten Nanoresonatoren hoher Güte, kombiniert mit Quantenpunkten, zukünftig als Quelle einzelner, ununterscheidbarer Photonen in der Quanteninformationsverarbeitung dienen.
Die Suche nach dem Absoluten. Zum 150. Geburtstag von Max Planck
Authors: Jacobi Manfred 
Published: February 2008

AbstractIn diesem Jahr jährt sich der Geburtstag von Max Planck zum 150. Mal. Als Schöpfer der Quantentheorie und als unermüdlicher Wissenschaftsorganisator verkörpert er eine einzigartige Persönlichkeit der Physikgeschichte. Als Physiker und als Mensch stand Planck an der Schwelle zum Übergang in ein neues Zeitalter.
Magnetismus mit Dreh. Spinspiralen an Oberflächen
Authors: von Bergmann Kirsten , Bode Matthias , Wiesendanger Roland 
Published: February 2008

AbstractNach der Theorie sind magnetische Spiralen auf atomarer Ebene möglich, die nur rechts‐ oder nur linksdrehend sind. Für den bevorzugten Drehsinn kann die sogenannte Dzyaloshinskii‐Moriya‐(DM)‐Wechselwirkung sorgen. Dazu muss sie stark genug sein, zudem darf das Gesamtsystem keine Inversionssymmetrie besitzen. Die DM‐Wechselwirkung beeinflusst den antiferromagnetischen Grundzustand so, dass die Spins sich nicht antiparallel ausrichten, sondern eine Spinspirale bilden. Eine solche Spirale wurde nun das erste Mal an einer Oberfläche nachgewiesen, die allein durch ihr Vorhandensein die Inversionssymmetrie bricht. Das Experiment wurde an einer atomar dünnen Manganschicht auf einem unmagnetischen Wolfram‐Substrat durchgeführt. Der Effekt könnte in der Spintronik Anwendung finden.
Ketchup – frisch gestrichen
Authors: Vilgis Thomas 
Published: February 2008

AbstractSelbst die Currywurst an der Imbissbude inspiriert zu physikalisch orientierten Kreationen, vor allem das über die Wurst geschwappte Ketchup. Denn diese profane Tomatensauce ist ein willkommenes Studienobjekt für ganz besondere Fließeigenschaften. Entgegen ausgetretenen Pfaden bereiten wir heute grünes “Ketchup” aus Cornichons, die französische Variante der Essiggürkchen. Das Problem dabei ist, die Fließeigenschaften, fest in Ruhe, flüssig unter Scherkräften, genau einzustellen.
Monsterwellen aus Licht
Authors: Solli Daniel R. , Jalali Bahram , Ropers Claus 
Published: February 2008

AbstractSeit Jahrhunderten berichten Seefahrer von gigantischen Wellen, die scheinbar aus dem Nichts und ohne Vorwarnung auftauchen. Erst Mitte der 1990er‐Jahre hat sich die Erkenntnis durchgesetzt, dass es sie wirklich gibt und sie für eine größere Zahl katastrophaler Schiffsunglücke verantwortlich waren. In Experimenten an der University of California in Los Angeles haben wir vor kurzem überraschenderweise in Lichtleitfasern Monsterwellen aus Licht nachgewiesen. Ursache hierfür ist eine Nichtlinearität der Faser.
Grüße vom Merkur
Authors: Bührke Thomas 
Published: February 2008

AbstractAm 14. Januar flog die amerikanische Raumsonde Messenger am sonnennächsten Planeten Merkur vorbei. Dabei näherte sie sich bis auf 200 Kilometer der Oberfläche. Es ist der erste Besuch einer Sonde seit den Vorbeiflügen von Mariner 10 Mitte der 1970er Jahre. Sieben wissenschaftliche Instrumente sammelten bei diesem Vorbeiflug Messdaten, und eine Kamera funkte mehr als 12000 Aufnahmen zur Erde. Sie zeigen eine von Kratern zerklüftete Oberfläche, die auf den ersten Blick an die des Mondes erinnert. Doch in mancherlei Hinsicht unterscheidet sich Merkur von dem Erdtrabanten.
Kann man die chinesische Mauer vom Mond aus sehen?
Authors: Müller Andreas 
Published: February 2008

AbstractDer italienische Physiker Enrico Fermi war berühmt für seine Fähigkeit, eine komplexe Fragestellung auf das Wesentliche zu reduzieren und größenordnungsmäßig zu lösen. Bis heute sind Fermi‐Fragen und Fermi‐Lösungen eine beliebte Möglichkeit, um physikalische Vorgänge im Alltag oder auch fundamentale Fragestellungen zu klären. Mit der neuen Serie Fermis Corner wollen wir diese Kunst fortführen.
A template‐finding algorithm and a comprehensive benchmark for homology modeling of proteins
Authors: Vallat Brinda Kizhakke , Pillardy Jaroslaw , Elber Ron 
Published: February 2008

AbstractThe first step in homology modeling is to identify a template protein for the target sequence. The template structure is used in later phases of the calculation to construct an atomically detailed model for the target. We have built from the Protein Data Bank (PDB) a large‐scale learning set that includes tens of millions of pair matches that can be either a true template or a false one. Discriminatory learning (learning from positive and negative examples) is used to train a decision tree. Each branch of the tree is a mathematical programming model. The decision tree is tested on an independent set from PDB entries and on the sequences of CASP7. It provides significant enrichment of true templates (between 50 and 100%) when compared to PSI‐BLAST. The model is further verified by building atomically detailed structures for each of the tentative true templates with modeller. The probability that a true match does not yield an acceptable structural model (within 6 Å RMSD from the native structure) decays linearly as a function of the TM structural‐alignment score. Proteins 2008. © 2008 Wiley‐Liss, Inc.
An integrated approach to inferring gene–disease associations in humans
Authors: Radivojac Predrag , Peng Kang , Clark Wyatt T. , Peters Brandon J. , Mohan Amrita , Boyle Sean M. , Mooney Sean D. 
Published: February 2008

AbstractOne of the most important tasks of modern bioinformatics is the development of computational tools that can be used to understand and treat human disease. To date, a variety of methods have been explored and algorithms for candidate gene prioritization are gaining in their usefulness. Here, we propose an algorithm for detecting gene–disease associations based on the human protein–protein interaction network, known gene–disease associations, protein sequence, and protein functional information at the molecular level. Our method, PhenoPred, is supervised: first, we mapped each gene/protein onto the spaces of disease and functional terms based on distance to all annotated proteins in the protein interaction network. We also encoded sequence, function, physicochemical, and predicted structural properties, such as secondary structure and flexibility. We then trained support vector machines to detect gene–disease associations for a number of terms in Disease Ontology and provided evidence that, despite the noise/incompleteness of experimental data and unfinished ontology of diseases, identification of candidate genes can be successful even when a large number of candidate disease terms are predicted on simultaneously. Availability: www.phenopred.org. Proteins 2008. © 2008 Wiley‐Liss, Inc.
fRMSDPred: Predicting local RMSD between structural fragments using sequence information
Authors: Rangwala Huzefa , Karypis George 
Published: February 2008

AbstractThe effectiveness of comparative modeling approaches for protein structure prediction can be substantially improved by incorporating predicted structural information in the initial sequence‐structure alignment. Motivated by the approaches used to align protein structures, this article focuses on developing machine learning approaches for estimating the RMSD value of a pair of protein fragments. These estimated fragment‐level RMSD values can be used to construct the alignment, assess the quality of an alignment, and identify high‐quality alignment segments. We present algorithms to solve this fragment‐level RMSD prediction problem using a supervised learning framework based on support vector regression and classification that incorporates protein profiles, predicted secondary structure, effective information encoding schemes, and novel second‐order pairwise exponential kernel functions. Our comprehensive empirical study shows superior results compared with the profile‐to‐profile scoring schemes. We also show that for protein pairs with low sequence similarity (less than 12% sequence identity) these new local structural features alone or in conjunction with profile‐based information lead to alignments that are considerably accurate than those obtained by schemes that use only profile and/or predicted secondary structure information. Proteins 2008. © 2008 Wiley‐Liss, Inc.
Thermal‐prehistory dependence of the phase stability in the structural phase transitions of Na2SO4 crystal
Authors: Choi Byoung‐Koo 
Published: February 2008

AbstractAfter as‐grown Na2SO4 (V) crystal is transformed to high‐temperature phase (I), the transition sequence is I → II → III on cooling and III → I on reheating scan. The intermediate phase II occurs within a very narrow temperature range of 2–3 °C and the transition temperature of II → III has been known to be much reduced during subsequent cooling scans. Here, we found that all the transitions I → II → III as well as III → I depend greatly on the thermal prehistory. This is possibly related to an incompleteness of the transition from phase V to I near 240 °C. We also found that if the Na2SO4 (I), which is just transformed from the phase V, is heated above 600 °C, then all the peculiarities on transitions surprisingly disappear. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Atomistic force field and electronic properties of carbazole: from monomer to macrocycle
Authors: Vehoff Thorsten , Kirkpatrick James , Kremer Kurt , Andrienko Denis 
Published: February 2008

AbstractAn atomistic force‐field is developed for carbazole monomers, oligomers, and alkyne‐substituted polymers. This force‐field can be used to study the morphology of stacks of carbazole macrocycles. Charge transport of macrocycles in columnar arrangement is analyzed using non‐adiabatic high‐temperature Marcus theory. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Exciton dephasing in quantum dots: Coupling to LO phonons via excited states
Authors: Muljarov E. A. , Zimmermann R. 
Published: February 2008

AbstractWe have found a novel mechanism of spectral broadening and dephasing in quantum dots (QDs) due to the coupling to longitudinal‐optical (LO) phonons. In theory, this mechanism comes into play only if the complete manifold of exciton levels (including those in the wetting‐layer continuum) is taken into account. We demonstrate this nontrivial dephasing in different types of QDs, using the exactly solvable quadratic coupling model, here generalized to an arbitrary number of excitonic states. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tyrosinase‐catalysed grafting of food‐grade gallates to chitosan: surface properties of novel functional coatings
Authors: Vartiainen Jari , Rättö Marjaana , Lantto Raija , Nättinen Kalle , Hurme Eero 
Published: February 2008

AbstractPlasma‐activated biaxially oriented polypropylene (BOPP) films and paper substrate have been coated with functional chitosan solutions. Plasma treatment increased the amount of surface peroxide groups and carboxyl groups on the BOPP films. As a result of plasma activation, the surface energy increased from 30 to 50 dynes/cm. The enzyme tyrosinase catalysed the grafting of octyl gallate and dodecyl gallate to amino groups of chitosan polysaccharide. Resulting coatings exhibited strong antimicrobial activity against Gram‐positive Staphylococcus aureus and Gram‐negative Listeria innocua. After 24 h of incubation, a total reduction in both bacteria cell numbers varied between >4.9 and 1.4 logarithmic units. Grafted dodecyl gallate and octyl gallate at pH 6 were found to have the lowest reduction values of <3 logarithmic units for S. aureus, while 1.4 logarithmic reduction value was obtained for grafted dodecyl gallate at pH 6 against L. innocua. Chitosan coatings were also effective barrier layers against oxygen transmission although the transmission rates clearly increased in high‐humidity conditions. In dry conditions, however, the transmission rate of 2 cm3/(m2 · 24 h) was obtained with chitosan‐coated BOPP. Coatings did not have any effects on water vapour transmission. Both gallates were successfully grafted at pH 6. As increased flocculation and colour formation indicated, the tyrosinase‐catalysed grafting was more powerful with octyl gallate. Dodecyl gallate containing chitosan coatings was more hydrophobic as compared to octyl gallate. Total migration of substances into 95% ethanol was ≥5 mg/dm2, thus materials may be exploitable in packaging purposes in direct contact with certain foodstuffs. Copyright © 2008 John Wiley & Sons, Ltd.
Spatial distribution of cloud cover
Authors: Garcia Pedro , Benarroch Ana , Riera Jose Manuel 
Published: February 2008

AbstractSatellite systems and high‐altitude platform systems working in Ka and V bands require the application of adaptive techniques in order to mitigate link degradations caused by atmospheric impairments such as those due to cloud cover. Among these techniques, resource sharing system techniques and site diversity need information on the spatial distribution of impairments caused by cloud cover, including the probability of simultaneous occurrence of adverse conditions in various regions.A study has been performed in Spain, within the framework of COST Action 280, to investigate the large‐scale spatial distribution of cloud cover using synoptic meteorological data. Cloud cover distribution for individual sites and the spatial correlation properties for pairs of sites have been investigated. The geographical distributions of the values obtained from the statistical analysis have been represented in maps of contour lines using standard mapping procedures. Correlation parameters are expected to decrease with distance; however, the maps derived taking a given site as reference reveal a significant influence of climatic and geographic factors such as weather fronts, orography or the proximity to the sea. The statistics and maps obtained can be useful to optimize power sharing in multi‐beam satellite systems, as suggested in this paper. Copyright © 2008 John Wiley & Sons, Ltd.
Channel estimation and physical layer adaptation techniques for satellite networks exploiting adaptive coding and modulation
Authors: Cioni Stefano , De Gaudenzi Riccardo , Rinaldo Rita 
Published: February 2008

AbstractThe exploitation of adaptive coding and modulation techniques for broadband multi‐beam satellite communication networks operating at Ka‐band and above has been shown to theoretically provide large system capacity gains. In this paper, the problem of how to accurately estimate the time‐variant channel and how to adapt the physical layer taking into account the effects of estimator errors and (large) satellite propagation delays is analyzed, and practical solutions for both the forward and the reverse link are proposed. A novel pragmatic solution to the reverse link physical layer channel estimation in the presence of time‐variant bursty interference has been devised. Physical layer adaptation algorithms jointly with design rules for hysteresis thresholds have been analytically derived. The imperfect physical layer channel estimation impact on the overall system capacity has been finally derived by means of an original semi‐analytical approach. Through comprehensive system simulations for a realistic system study case, it is showed that the devised adaptation algorithms are able to successfully track critical Ka‐band fading time series with a limited impact on the system capacity while satisfying the link outage probability requirement. Copyright © 2008 John Wiley & Sons, Ltd.
Learning to read scientific text: Do elementary school commercial reading programs help?
Authors: Norris Stephen P. , Phillips Linda M. , Smith Martha L. , Guilbert Sandra M. , Stange Donita M. , Baker Jeff J. , Weber Andrea C. 
Published: February 2008

AbstractThis paper describes a comprehensive set of studies designed to assess the potential for commercial reading programs to teach reading in science. Specific questions focus on the proportion of selections in the programs that contain science and the amount of science that is in those selections, on the genres in which the science is portrayed, on the areas and topics of science covered, on the accuracy of the scientific content, on the text features used to communicate the science, and on the instructional strategies and assessment techniques recommended. The findings show that commercial reading programs have changed substantially from the days when they were dominated by literary texts and contained hardly any science. Now, there is a variety of genres and scientific content in about one fifth of the selections. The content is also generally accurate. So, there is considerable potential offered by these programs for teaching children to read science. Unfortunately, the findings also show that the recommended instructional strategies and assessment techniques do little to capitalize upon this potential. In particular, the findings demonstrate that, although most of the science is cast in the expository genre, most of the recommended instruction and assessment is more appropriate to the literary genres. © 2008 Wiley Periodicals, Inc.Sci Ed92:765–798, 2008
The elusiveness of spiritual wisdom in the art and science of nursing practice
Authors: Moreau Jeannine 
Published: February 2008

AbstractAs two students and a teacher immersed in practice education at a Canadian nursing school. We were curious about how to engage in spiritual health care practice, viewed as relational nursing practice that assumes interconnections of spirit, health and healing. This paper explores how to interpret theoretical understandings into pragmatics of teaching, learning and engaging in spiritual health care practice. There is discussion about story telling, taking a stand of ‘not knowing’ (Irving and Moffatt, 2002), opening space for diversity, authentic dialogue across, within and through difference to inform pragmatic ways of knowing, being and of doing spiritual health care. To inform the discussion, theoretical perspectives on the religion/spirituality divide, interconnections of health, healing and spirit, ‘defining moments’ and spiritual/sacred spaces are presented. A review of the literature juxtaposed with student/teacher experiences and perspectives helps to inform a deeper understanding of teaching, learning and engaging in spiritual health care practice. Copyright © 2008 John Wiley & Sons, Ltd.