bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ableitung und Untersuchung einer kinetischen Gleichung für räumlich homogene Systeme mit kollektiver Wechselwirkung. I
Authors: Bessenrodt R. 
Published: May 2007

AbstractFü nichtrelativistische, klassisch behandelbare, räumlich homogene Plasmen geringer Dichte, die sich bereits in Gleichgewichtsnähe befinden, werden aus der Liouville‐Gleichung unter Verzicht auf die üblichen räumlichen Fourier‐Transformationen eine einfache kinetische Gleichung abgeleitet sowie die Gültigkeit der Erhaltungssätze und des H‐Theorems gezeigt.
Zur Theorie der Leitfähigkeit von Elektrolyten und schwach ionisierten Plasmen. II
Authors: Kremp D. , Kraeft W.‐D. , Ebeling W. 
Published: May 2007

AbstractOur starting point is an equation for the pair distribution function given in part I. In part I this equation was solved by a perturbation procedure in terms of the BJERRUM parameter b and the first two approximations were given (containing terms up to b2). In this paper there are calculated the distribution function and the conductance of symmetrical electrolytes up to all powers of the BJERRUM parameter. In respect to the concentration n all the powers higher than n and n log n respectively are neglected. Only the terms up to b2 are screened (DEBYE screening). In this way long range divergencies in the conductance are avoided. For high b values there is a large decrease of conductance which is due to ionic association. The asymptotic representation of the conductance is given by σ/σ = 1 − 4π n a3 (exp b)/b.
Energie‐Reichweite‐Kurve für 7Li‐Ionen in Luft
Authors: Mösner J. , Schmidt G. , Schintlmeister J. 
Published: May 2007

AbstractMit Hilfe einer Nebelkammer untersuchten wir die Reaktion 14N (n, 2α)7Li. Die Kammer war mit Luft und Wasserdampf gefüllt. Es wurden insgesamt 1127 Ereignisse ausgemessen. Aus den beiden α‐Spuren konnte unter Benutzung der gut bekannten Energie‐Reichweite‐Kurve für α‐Teilchen und durch Anwendung des Impulssatzes die Energie der zugehörigen 7Li‐Spur berechnet werden. Für den Energiebereich 0,1 bis 5,0 MeV werden die mittleren Reichweiten von 7Li‐Ionen in trockener Luft von 15 °C und 760 Torr angegeben.
Zum Wirkungsquerschnitt depolarisierender Stöβe. I. Die Berechnung des Wirkungsquerschnittes aus Polarisationsgradmessungen
Authors: Ermisch W. 
Published: May 2007

AbstractUnter vereinfachenden Annahmen und gewissen Vernachlässigungen wurden Gleichungen abgeleitet, die es gestatten, aus der Größe des gemessenen Polarisationsgrades der Resonanzfluoreszenz eines Atomdampfes die Stoßzahlen und Stoßquerschnitte für depolarisierende Stöße, die durch ein zugefügtes Fremdgas verursacht werden, zu ermitteln. Hierbei wurde der Einfluß der Versuchsanordnung und der Einfluß gleichzeitig auftretender Effekte wie Strahlungsdiffusion, löschende Stöße und Phasenstörungsstöße als auch die Anisotropie der Fluoreszenzabklingdauer berücksichtigt.
Zur Thermodynamik von Systemen mit zwei Temperaturen
Authors: Ziemann H. 
Published: May 2007

AbstractDer erste und zweite Hauptsatz der Thermodynamik werden auf Systeme verallgemeinert, deren stabile Zustände durch zwei Temperaturen gekennzeichnet sind. Die Abgrenzung solcher Systeme gegenüber denen der konventionellen Art erfolgt durch die Forderung, daß sie durch äußere Parameter und zwei zusätzliche Variable beschrieben werden können. Ihre Wechselwirkungen miteinander haben die in der herkömmlichen Theorie zugrunde gelegte Struktur. Diese Wechselwirkungen definieren im Verein mit der genannten Voraussetzung über Anzahl und Art der zur Beschreibung notwendigen Parameter zwei Temperaturen und zwei innere Energien. Ferner gestattet der eine von zwei möglichen Systemtypen die Konstruktion einer Entropie. An dieser Stelle wird nur dieser Typ behandelt.
Zur statistischen Thermodynamik von Teilchensystemen mit kurz‐ und weitreichenden Wechselwirkungen
Authors: Schmitz G. 
Published: May 2007

AbstractAuf der Grundlage der BBGKY‐Hierarchie werden für klassische Systeme von Teilchen unter Berücksichtigung von kurz‐ und weitreichenden Wechselwirkungen die molekularen Verteilungsfunktionen berechnet. Die Hierarchie wird durch eine konvergente uneigentliche Dichteentwicklung gelöst. Die freie Exzeßenergie wird über einen Aufladungsprozeß bis zum vierten Koeffizienten in der Entwicklung angegeben.
Über anomale GREENsche Funktionen für flüssiges Helium 4
Authors: Fritzsch K. 
Published: May 2007

AbstractIn kondensierten Systemen vieler Teilchen sind anomale GREENsche Funktionen, so z. B. die aus drei Erzeugungs‐ bzw. Vernichtungsoperatoren bestehende Dreihalbe‐Funktion zu beachten. Aussagen über Dreihalbe‐Funktionen mit äußeren Phononlinien, die bisher mit phänomenologischen Argumenten geltend gemacht worden sind, werden mikroskopisch begründet. In den Selbstenergieteilen führen die anomalen Beiträge zu Singularitäten, die sämtlich behoben werden können. Im Zerfallsbereich gelingt dies durch Annahme einer komplexen Anregungsenergie.
Anlaufvorgang der Molekularströmung in Rohren mit Teilchenadsorption bei nichtlinearer Adsorptionsisotherme
Authors: Teubner W. , Paul G. 
Published: May 2007

AbstractDer Anlaufvorgang der molekularen Strömung von Gasen durch Rohre wird als Diffusionsproblem behandelt und die Verzögerungszeit bis zur Einstellung stationärer Verhältnisse bei physikalischer Adsorption von Teilchen für verschiedene Adsorptionsisothermen berechnet. Dazu dient eine Methode von Frisch, nach der sich die Verzögerungszeit unter Umgehung einer Lösung der im allgemeinen nichtlinearen Differentialgleichung aus den Daten der stationären Strömung ermitteln läßt. Das Verfahren wird für die Adsorptionsisothermen nach Langmuir sowie nach Dubinin und Raduškevič angewendet, wobei Aussagen über die Genauigkeit einer von Clausing angegebenen einfachen Näherungsformel für die Verzögerungszeit möglich sind. In Umkehrung der Problemstellung wird gezeigt, wie sich aus Ergebnissen von Strömungsexperimenten Adsorptionsisothermen gewinnen lassen.
Vereinfachung der Störungstheorie von Atomen und Molekülen durch Verwendung separabler Potentiale
Authors: Hausmann K. 
Published: May 2007

AbstractEs wird aus den im Grundzustand besetzten Hartree‐Fock‐Einelektronenwellen‐funktionen ein einfacher Modellhamiltonoperator konstruiert. Dieser Einelektronenoperator enthält außer der kinetischen Energie eine Überlagerung von Projektionsoperatoren. Er besitzt als gebundene Zustände nur die besetzten Hartree‐Fock‐Zustände. Die Berechnung der unbesetzten Zustände und damit der Störungsterme ist wesentlich einfacher als beim Hartree‐Fock‐Operator. Für das Heliumatom konvergiert die zum Modelloperator gehörende Störungsreihe fast ebenso rasch wie die Störungstheorie ausgehend vom Hartree‐Fock‐Operator.
Einschwingvorgänge der magnetischen Resonanz und subharmonische Resonanzen beim optischen Pumpen an 201Hg
Authors: Cappeller U. , Dellit L. 
Published: May 2007

AbstractThe dynamical equations for optical pumping are studied in the case of the alignment of 201Hg. The transients of the magnetic resonance in the ground state (I = 3/2) and subharmonic resonances in a linearly polarized H1‐field are observed.
Comparison of colour development in sugar–amino acid solutions with colour changes in wood during drying
Authors: McCurdy Murray C. , Pang Shusheng 
Published: May 2007

AbstractKiln brown stain (KBS) is a major concern in the drying of high‐grade softwood due to the darkened wood surface. Although numerous studies have been conducted in the last decade, the mechanism of the KBS formation is still not fully understood. One theory is that the KBS is caused by Maillard reaction between the concentrated sap solution and the surrounding drying medium during drying. The present study has investigated this theory using artificial sap solution at various concentrations. Colour development of these solutions treated at different temperatures is measured and compared with the actual colour changes in Pinus radiata sapwood during drying. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.
Competitive hydrogen bonding mechanisms underlying phase behavior of triple poly(N‐vinyl pyrrolidone)–poly(ethylene glycol)–poly(methacrylic acid‐co‐ethylacrylate) blends
Authors: Kireeva Polina E. , Shandryuk Georgy A. , Kostina Julia V. , Bondarenko Galina N. , Singh Parminder , Cleary Gary W. , Feldstein Mikhail M. 
Published: May 2007

AbstractDifferential scanning calorimetry (DSC) of triple blends of high molecular weight poly(N‐vinyl pyrrolidone) (PVP) with oligomeric poly(ethylene glycol) (PEG) of molecular weight 400 g/mol and copolymer of methacrylic acid with ethylacrylate (PMAA‐co‐EA) demonstrates partial miscibility of polymer components, which is due to formation of interpolymer hydrogen bonds (reversible crosslinking). Because both PVP and PMAA‐co‐EA are amorphous polymers and PEG exhibits crystalline phase, the DSC examination is informative on the phase state of PEG in the triple blends and reveals a strong competition between PEG and PMAA‐co‐EA for interaction with PVP. The hydrogen bonding in the triple PVP–PEG–PMAA‐co‐EA blends has been established with FTIR Spectroscopy. To evaluate the relative strengths of hydrogen bonded complexes in PVP–PEG–PMAA‐co‐EA blends, quantum‐chemical calculations were performed. According to this analysis, the energy of H‐bonding has been found to diminish in the order: PVP–PMAA‐co‐EA–PEG(OH) > PVP–(OH)PEG(OH)–PVP > PVP–H2O > PVP–PEG(OH) > PMAA‐co‐EA–PEG(O) > PVP–PMAA‐co‐EA > PMAA‐co‐EA–PEG(OH). Thus, most stable complexes are the triple PVP–PMAA‐co‐EA–PEG(OH) complex and the complex wherein comparatively short PEG chains form simultaneously two hydrogen bonds to PVP carbonyl groups through both terminal OH‐groups, acting as H‐bonding crosslinks between longer PVP backbones. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Designing acrylamide‐ and methacrylate‐based novel supports for lipase immobilization
Authors: Chauhan Ghanshyam S. , Chauhan Sandeep , Kumar Yogesh , Thakur Usha Sen , Kanwar S. S. , Kaushal Rajeev 
Published: May 2007

AbstractTo design efficient polymeric supports for lipase immobilization, two series of hydrogels based on acrylamide and three methacrylates were prepared via crosslinking with ethylene glycol methacrylate and N,N‐methylenebisacrylamide. The three methacrylates used to prepare these hydrogels had different alkyl chain lengths: C1 (methyl methacrylate), C12 (dodecyl methacrylate), and C18 (octadecyl methacrylate). In the reaction scheme, only the feed concentration of the hydrophobic component (methacrylate) was varied. The characterization of the hydrogels was carried out with Fourier transform infrared, scanning electron microscopy, and nitrogen analysis to establish their structural aspects and to obtain evidence for network formation; the swelling and water uptake of the hydrogels were studied as functions of the time, temperature, and pH. Lipase immobilization on selected hydrogels was studied as a function of the concentration of the methacrylate used in the feed and the nature of the crosslinker. The activity of the hydrogel series that showed the highest activity of the immobilized lipase was investigated further as a function of the methacrylate feed concentration, pH, and temperature. Some organic solvents were studied to investigate the effect of the nature of the solvent on the activity of the immobilized lipase. The activity of the immobilized lipase was more than that of the free lipase and was affected by the structural attributes of the polymeric supports and by the nature of the solvent. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Properties of films from corn zein reacted with glutaraldehyde
Authors: Sessa David J. , Mohamed Abdellatif , Byars Jeffrey A. , Hamaker Sharon A. H. , Selling Gordon W. 
Published: May 2007

AbstractTo improve the mechanical properties of zein films, a commercial white zein was reacted in glacial acetic acid (HAc) with glutaraldehyde (GDA) from 0.5 to 16% by weight based on the weight of zein. Amounts of 4% or higher GDA‐modified zein, when cured in a closed system, generated a gel. That gel was insoluble in organic solvents known to solubilize zein. Zein solutions cast within a silicon rubber gasket sealed onto Teflon‐coated plates, when air dried, generated 0.7–0.9‐mm thick films. Those films from 8% GDA‐modified zein had a water vapor permeability of 5.9 × 10−8 g cm/Pa s m2. Overall, results indicate that our thicker films gave higher water vapor permeability than values reported in the literature. To achieve consistent and comparable results with differential scanning calorimetry (DSC) and dynamic mechanical analyses (DMA), film samples had to be heated to remove residual HAc. An increase in the glass transition temperatures for those films from GDA‐modification of zein, observed with both DSC and DMA, was attributed to the crosslinking of zein. Physical testing of tensile bars cut from GDA‐modified zein films showed minor enhancement of tensile strength, percent elongation, and Young's modulus in the 0.5% GDA‐modified zein films, which increased and leveled off with 4% or higher amounts of GDA for the modifications. When the 4 to 16% GDA results are averaged, the tensile strength for the modified zein films increased 1.8‐fold when compared with unmodified zein control films. On the same note, percent elongation showed a 1.8‐fold increase and Young's modulus showed a 1.5‐fold increase. GDA reaction with zein generated films with improved tensile strength, ductility, and stiffness when compared with respective zein control films that retained their integrity when subjected to either boiling water or extensive soaking. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Electrical properties of segregated ultrahigh molecular weight polyethylene/multiwalled carbon nanotube composites
Authors: Xi Ying , Yamanaka Atsuko , Bin Yuezhen , Matsuo Masaru 
Published: May 2007

AbstractMultiwalled carbon nanotubes (MWNTs) and ultrahigh molecular weight polyethylene (UHMWPE) composites are prepared using paraffin as solvent. The resulting electrical properties show lower electrical percolation threshold, which is 1.4 vol %, than that of UHMWPE‐MWNT composites prepared by gelation/crystallization from decalin solution. Good reproducibility and higher maximum of electrical conductivity are obtained. The extremely low electrical percolation threshold indicates that the dispersion of MWNTs is segregated, which can be proved by the morphology of the film observed by optical microscopy. The complex planes of electric modulus are useful to analyze the dispersion of MWNTs and the quality of interparticle contacts. In addition, the result of thermogravimetry shows that the retardation of onset of UHMWPE decomposition in inert gas is observed in the mixture with MWNTs. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Superabsorbent hydrogel based on modified polysaccharide for removal of Pb2+ and Cu2+ from water with excellent performance
Authors: Guilherme Marcos R. , Reis Adriano V. , Paulino Alexandre T. , Fajardo André R. , Muniz Edvani C. , Tambourgi Elias B. 
Published: May 2007

AbstractThis contribution describes the absorption percentage of Pb2+ and Cu2+ from water by a superabsorbent hydrogel matrix (SH) made from an anionic polysaccharide copolymerized with acrylic acid (AAc) and acrylamide (AAm). Metal‐absorption tests, upon sequential pH variation, indicated that the SH has pH‐sensitivity for the absorption of both metals from solution, attributed to the functional ionic groups (COOH) present in the AAc and arabic gum (AG) segments. At the pH 5.0, the SH exhibited good absorption capacity: 73.10% for Pb2+, 81.99% for Cu2+ in water and 63.64% for Pb2+, and 76.67% for Cu2+ in saline water with 0.1 mol kg−1 ionic strength. A replicated 22 full factorial design with a central point was built to evaluate the maximum absorption capacity of the metals into the SH. It was found that both the interaction and main effects of the pH and the initial concentration of metal solution on absorption percentage of the metals were statistically significant. Surface response plots indicated that the absorption capacity of both metals into the SH may be appreciably improved by using the solutions with lower initial concentration of metal and with higher pH values. Metal‐absorption results demonstrated that the SH is a convenient material for absorption of Pb2+ and Cu2+ from pure aqueous and saline aqueous environments. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Behavior of α‐ and β‐cyclodextrin‐encapsulated allyl isothiocyanate as slow‐release additives in polylactide‐co‐polycaprolactone films
Authors: Plackett David , Ghanbari‐Siahkali Afshin , Szente Lajos 
Published: May 2007

AbstractThe natural antibacterial agent allyl isothiocyanate (AITC) encapsulated in either α‐ or β‐cyclodextrin (CD) has previously been evaluated as a slow‐release additive in polylactide‐co‐polycaprolactone (PLA–PCL) films designed for use in cheese packaging. In the research described in this article, thermogravimetric analysis (TGA) and thermogravimetric analysis in tandem with mass spectrometry (TGA–MS) were used to explore the thermal properties of CD‐encapsulated AITC complexes as well as those of PLA–PCL films containing these complexes. To our knowledge, this is the first reported application of the TGA–MS technique to explore the thermal stability of CD‐entrapped AITC and the first study to report differences in thermal stability of AITC in α‐and β‐CD cavities in the solid state. Observed differences in the thermal degradation profile of films containing the CD complexes can be explained if AITC binds more strongly to β‐CD than to α‐CD. This hypothesis has been reinforced by gas chromatography (GC) and high performance liquid chromatography (HPLC) studies, the results of which suggest that a new covalently bound AITC–CD complex may be formed when incorporating the β‐CD complex of AITC in PLA–PCL films but not when incorporating the α‐CD complex of AITC. This finding means that the α‐CD complex of AITC would be preferred in situations where adequate long‐term controlled release of AITC from polymer films is required, as for example in the case of active packaging applications. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Alternating‐current impedance and chronoamperometry studies of poly(vinylidene fluoride‐co‐hexafluoropropylene)–polyacrylonitrile‐based microporous polymer blend electrolytes prepared by a phase‐inversion technique
Authors: Sundaram N. T. Kalyana , Vasudevan T. , Subramania A. 
Published: May 2007

AbstractThis article describes a comparative study of poly(vinylidene fluoride‐co‐hexafluoropropylene)–polyacrylonitrile‐based plain gel polymer blend electrolytes and microporous gel polymer blend electrolytes. Scanning electron microscopy, differential scanning calorimetry, alternating‐current impedance, chronoamperometry, and dielectric spectroscopy studies were carried out. The microporous gel polymer blend electrolytes enhanced the ionic conductivity, lithium transference number, and dielectric permittivity, and this could be attributed to a higher uptake of the electrolyte solution (an increase in the number of charge carriers) by the porous structure. The temperature dependence of the ionic conductivity of the polymer electrolyte followed an Arrhenius relationship. An LSV experiment was carried out to investigate the electrochemical stability in the polymer electrolyte. Finally, charge–discharge studies of lithium‐ion cells made from the coupling of gel polymer blend electrolytes (plain and microporous) with LiMg0.10Mn1.90O4 as a cathode and carbon as an anode were conducted. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Preparation of poly(methyl methacrylate) nanocomposites with superior impact strength
Authors: Singh Dhananjay , Jayasimha T. , Rai K. N. , Kumar Anil 
Published: May 2007

AbstractA chemically stable syrup of poly(methyl methacrylate) in its monomer was prepared with a suitable dual‐initiating system. Nanoalumina particles were prepared by the autoignition of aluminum nitrate with urea and were made compatible with the organic medium by chemical modification with methacrylol isocyanate. The polymer syrup prepared in this way was applied between two poly(methyl methacrylate) sheets (each 10 cm × 10 cm × 2 mm), and the composite thus prepared was tested with a bullet‐firing machine and a drop‐weight‐impact testing machine. The impact strength measurements of the two‐plate composite from both of these procedures showed that the impact resistance doubled in the case of nanoalumina. The modeling of the damage to the multilayered composite by the critical impact energy was performed with the relation E = pn2 + qn + r, where E is the impact energy, p, q, and r are constants, and n is the number of layers. Experiments showed that the presence of nanoparticles in the adhesive increased the value of the constants. The 10‐layer composite was further tested with a 0.32 Indian Ordinance Factory (IOF) revolver with a bullet mass of 9.9 g and a muzzle velocity of 236 ± 7 m/s (muzzle energy = 275 J) from a 10‐m distance, which produced an ordinary indentation with no penetration. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Betweenness centrality as an indicator of the interdisciplinarity of scientific journals
Authors: Leydesdorff Loet 
Published: May 2007

AbstractIn addition to science citation indicators of journals like impact and immediacy, social network analysis provides a set of centrality measures like degree, betweenness, and closeness centrality. These measures are first analyzed for the entire set of 7,379 journals included in the Journal Citation Reports of the Science Citation Index and the Social Sciences Citation Index 2004 (Thomson ISI, Philadelphia, PA), and then also in relation to local citation environments that can be considered as proxies of specialties and disciplines. Betweenness centrality is shown to be an indicator of the interdisciplinarity of journals, but only in local citation environments and after normalization; otherwise, the influence of degree centrality (size) overshadows the betweenness‐centrality measure. The indicator is applied to a variety of citation environments, including policy‐relevant ones like biotechnology and nanotechnology. The values of the indicator remain sensitive to the delineations of the set because of the indicator's local character. Maps showing interdisciplinarity of journals in terms of betweenness centrality can be drawn using information about journal citation environments, which is available online.
Can citation analysis of Web publications better detect research fronts?
Authors: Zhao Dangzhi , Strotmann Andreas 
Published: May 2007

AbstractWe present evidence that in some research fields, research published in journals and reported on the Web may collectively represent different evolutionary stages of the field, with journals lagging a few years behind the Web on average, and that a “two‐tier” scholarly communication system may therefore be evolving. We conclude that in such fields, (a) for detecting current research fronts, author co‐citation analyses (ACA) using articles published on the Web as a data source can outperform traditional ACAs using articles published in journals as data, and that (b) as a result, it is important to use multiple data sources in citation analysis studies of scholarly communication for a complete picture of communication patterns. Our evidence stems from comparing the respective intellectual structures of the XML research field, a subfield of computer science, as revealed from three sets of ACA covering two time periods: (a) from the field's beginnings in 1996 to 2001, and (b) from 2001 to 2006. For the first time period, we analyze research articles both from journals as indexed by theScience Citation Index(SCI) and from the Web as indexed byCiteSeer. We follow up by an ACA ofSCIdata for the second time period. We find that most trends in the evolution of this field from the first to the second time period that we find when comparing ACA results from theSCIbetween the two time periods already were apparent in the ACA results fromCiteSeerduring the first time period.