bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas barrier of polystyrene montmorillonite clay nanocomposites: Effect of mineral layer aggregation
Authors: Nazarenko S. , Meneghetti P. , Julmon P. , Olson B. G. , Qutubuddin S. 
Published: May 2007

AbstractThree polystyrene (PS)/clay hybrid systems have been prepared via in situ polymerization of styrene in the presence of unmodified sodium montmorillonite (Na‐MMT) clay, MMT modified with zwitterionic cationic surfactant octadecyldimethyl betaine (C18DMB) and MMT modified with polymerizable cationic surfactant vinylbenzyldimethyldodecylammonium chloride (VDAC). X‐ray diffraction and TEM were used to probe mineral layer organization and to expose the morphology of these systems. The PS/Na‐MMT composite was found to exhibit a conventional composite structure consisting of unintercalated micro and nanoclay particles homogeneously dispersed in the PS matrix. The PS/C18DMB‐MMT system exhibited an intercalated layered silicate nanocomposite structure consisting of intercalated tactoids dispersed in the PS matrix. Finally, the PS/VDAC‐MMT system exhibited features of both intercalated and exfoliated nanocomposites. Systematic statistical analysis of aggregate orientation, characteristic width, length, aspect ratio, and number of layers using multiple TEM micrographs enabled the development of representative morphological models for each of the nanocomposite structures. Oxygen barrier properties of all three PS/clay hybrid systems were measured as a function of mineral composition and analyzed in terms of traditional Nielsen and Cussler approaches. A modification of the Nielsen model has been proposed, which considers the effect of layer aggregation (layer stacking) on gas barrier. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1733–1753, 2007
Interpretation of the polyelectrolyte and antipolyelectrolyte effects of poly(N‐vinylimidazole‐co‐sodium styrenesulfonate) hydrogels
Authors: Valencia Joaquín , Piérola Inés F. 
Published: May 2007

AbstractHydrogels of N‐vinylimidazole (VI) and sodium styrenesulfonate (SSS) were synthesized in aqueous solution by radical crosslinking copolymerization with N,N′‐methylene‐bis(acrylamide) as crosslinker. Swelling in several saline solutions was measured for hydrogel samples synthesized with different comonomer concentrations (CT = 10, 25, or 40%) and with SSS mole fractions covering a broad range (fSSS = 0–0.7), while the crosslinker ratio was 2 wt % in all cases. The degree of swelling in aqueous solution with a specific ionic strength (μ), plotted versus the SSS composition of the feed, shows a minimum for any set of samples synthesized with a fixed CT. The dependence of swelling on μ shows both polyelectrolyte (fSSS beyond the minimum) and antipolyelectrolyte behaviors (in the low fSSS limit). It was found that the nonGaussian factor of the crosslinking density and the polymer‐solvent interaction parameter increase with fSSS for any CT. Moreover, in the low fSSS limit, the osmotic swelling pressure is governed not only by the ionic contribution, but also by the polymer‐solvent mixing and, the concentration of mobile counterions inside the gel is not proportional to the net fixed charge but to the addition of cationic and anionic side groups, what discards the formation of ionic pairs. The antipolyelectrolyte effect is interpreted as due to the increasing protonation of VI as μ goes up. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1683–1693, 2007
Molecular dynamics in PVDF/PVA blends as revealed by dielectric loss spectroscopy
Authors: Linares A. , Nogales A. , Rueda D. R. , Ezquerra T. A. 
Published: May 2007

AbstractThe relaxation behavior of a series of compatible poly(vinylidene fluoride) (PVDF) and poly(vinyl acetate) (PVA) blends has been investigated by dielectric spectroscopy in a broad frequency and temperature range. Blends with PVDF content higher than 60% in weight are semicrystalline. Semicrystalline blends show a relaxation (αc) occurring in the crystalline phase of PVDF. Both semicrystalline and amorphous blends exhibit two processes, α and β associated to the overall segmental dynamics and to localized motions in the amorphous phase, respectively. For high PVDF content samples, the β relaxation exhibits an anomalous behavior characterized by a crossover from segmental to local dynamics, upon decreasing temperature, attributed to confinement effects taking place in PVDF segregated regions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1653–1661, 2007
Significant variations in nuclear structure occur between and within Gleason grading patterns 3, 4, and 5 determined by digital image analysis
Authors: Veltri Robert W. , Marlow Cameron , Khan Masood A. , Miller Michael C. , Epstein Jonathan I. , Partin Alan W. 
Published: May 2007

AbstractBACKGROUNDAlterations in nuclei structure and DNA content captured from Gleason grading patterns 3, 4 and 5 of radical prostatectomy (RP) cases were determined by a computer‐assisted microscope. Quantitative Nuclear Morphometry (QNM) profiles were created to evaluate variability in nuclear structure within each of these grades.METHODSA tissue microarray (TMA) was constructed using RP cases and the prostate cancer (PCa) TMA cores prepared from 20 GG‐3, 9 GG‐4, 10 GG‐5 patterns, and 20 benign cancer‐adjacent cases from RP archival paraffin blocks. Feulgen‐stained nuclei were captured from 0.6 mm spots using the AutoCyte™ system. Pools of 1100 nuclei captured from each test group were used to calculate Multivariate Logistic Regression (MLR) models that generated predictive indices and predictive probabilities (PP) to make comparisons between and within each set of pooled nuclei.RESULTSA single QNM profiles yielded areas of receiver operator characteristic curves (ROC) that distinguished differences among benign cancer‐adjacent nuclei and GG‐3 (ROC‐AUC = 0.78); GG‐4 (ROC‐AUC = 0.86) and GG‐5 (ROC‐AUC = 0.88) with accuracies of 73%, 78% and 80% respectively. Applying PP plots generated from MLR models of GG 3, 4, and 5 nuclei clearly demonstrated marked heterogeneity within each of these three GG patterns.CONCLUSIONSQNM signatures illustrate alterations in nuclei structure, based upon nuclear morphometry within each of these three GG patterns, and might signify potential variations in PCa disease risk of progression outcomes. In the future a modified system of Gleason grading that considers not only glandular architecture but also quantitative nuclear grade may ensure accuracy in prognosis. Prostate 67: 1202–1210, 2007. © 2007 Wiley‐Liss, Inc.
Effect of metabolic inhibitors on ATP and citrate content in PC3 prostate cancer cells
Authors: Matheson B. K. , Adams J. L. , Zou J. , Patel R. , Franklin R. B. 
Published: May 2007

AbstractBACKGROUNDIn normal prostate epithelial cells low m‐aconitase activity decreases citrate oxidation leading to citrate accumulation. In prostate cancer cells m‐aconitase activity is increased and citrate content is lower. The effect of inhibition of m‐aconitase on ATP production by prostate cancer cells (PC3) is not known nor is the contribution of glycolysis versus respiration.METHODSATP content of PC3 cells as affected by inhibition of m‐aconitase (fluoroacetate (FA), zinc), inhibition of glycolysis (2DxG), or respiration (DNP, oligomycin) was determined. The ability to maintain ATP using glucose or glutamine as sole substrate was also determined. Intermediates including ATP, lactate, glucose, and glutamine were assayed in neutralized perchloric acid (PCA) cell extracts, virgin, and conditioned medium by enzymatic fluorometry.RESULTSData show that inhibition of m‐aconitase, glycolysis, or respiration alone did not decrease ATP content. Inhibition of both glycolysis and respiration were required to decrease ATP content. PC3 cells were able to produce ATP with either glucose or glutamine as sole substrate. Though FA clearly inhibited m‐aconitase there was no evidence that zinc had a similar effect.CONCLUSIONPC3 cells can support ATP production when m‐aconitase is inhibited by using glycolysis or oxidation of substrate (e.g., glutamine) entering the TCA cycle distal to citrate. Prostate 67: 1211–1218, 2007. © 2007 Wiley‐Liss, Inc.
Analysis of steroid estrogens in water using liquid chromatography/tandem mass spectrometry with chemical derivatizations
Authors: Lin Ying‐Hsuan , Chen Chia‐Yang , Wang Gen‐Shuh 
Published: May 2007

AbstractEven in trace amounts, estrogens such as 17β‐estradiol (E2), estrone (E1), estriol (E3), and 17α‐ethinyl estradiol (EE2) may have adverse effects on humans and the aquatic ecosystem. Therefore, it is essential to be able to measure trace amounts of steroid estrogens in water. To date, most instruments are not sensitive enough to detect these chemicals in small samples of water. Sensitivity, however, may be improved by using appropriate derivatization reagents to modify the structures of these estrogens so that their ionization efficiency is increased, making them more detectable by liquid chromatography/mass spectrometry (LC/MS). This study uses dansyl chloride, 2‐fluoro‐1‐methylpyridinium p‐toluenesulfonate (FMPTS), and pentafluorobenzyl bromide (PFBBr) as derivatization reagents to react with the phenolic estrogens to make them more detectable in water. We also test how environmental matrices (wastewater effluent, river water, and drinking water) influence the detectability of these estrogens. Both qualitative and semi‐quantitative comparisons of these derivatization methods were made. We found that dansyl chloride derivatives created signal intensities one or two orders of magnitude greater than those normally found in underivatized estrogen standards. The signals derived by FMPTS were analyte‐dependent, and the products derived from E1, E2, and EE2 produced 2.19 to 12.1 times the signal intensity of underivatized E1, E2, and EE2. The product derived from E3 produced weaker signals than that produced by underivatized E3. The PFBBr derivatives produced signals that were as much as 5.8 times those found in the underivatized estrogens. When these derivatization methods were applied to river water, drinking water and effluents from a sewage treatment plant (STP), the different matrices were found to significantly suppress the signals if we used electrospray ionization, though this influence became less significant if we used atmospheric pressure chemical ionization. This study suggests that PFBBr derivatization can best be used for the detection of these estrogens in complex environmental matrices such as river water and STP effluents and that the dansyl chloride derivatization is best used for clean samples such as drinking water. Copyright © 2007 John Wiley & Sons, Ltd.
Analysis of organic acid markers relevant to inherited metabolic diseases by ultra‐performance liquid chromatography/tandem mass spectrometry as benzofurazan derivatives
Authors: Al‐Dirbashi Osama Y. , Santa Tomofumi , Al‐Qahtani Khalid , Al‐Amoudi Mohammed , Rashed Mohamed S. 
Published: May 2007

AbstractWe describe a new approach applicable to the determination of organic acids that serve as diagnostic markers for several inherited metabolic disorders. We utilized liquid chromatography/tandem mass spectrometry for analysis of organic acid derivatives of a recently described benzofurazan reagent. The derivatization step was necessary to obtain organic acid derivatives suitable for analysis by reversed‐phase liquid chromatography with high ionization efficiency for mass spectrometry in the positive‐ion mode. In this work, a group of related dicarboxylic acid markers containing five or six carbon atoms were analyzed and validation was performed for glutaric and 3‐hydroxyglutaric acids, the specific markers for glutaric acidemia type 1. Derivatization was achieved by reacting untreated urine with the derivatization reagent under mild conditions. The reaction mixture was analyzed on a C18 ultra‐performance liquid chromatography (UPLC) column (50 × 2.1 mm, 1.7 µm) and detected in the multiple reaction monitoring mode in 5 min. Calibration curves were linear up to at least 1000 µM with detection limits for glutaric and 3‐hydroxyglutaric acids of 0.025 and 0.02 µM, respectively (signal‐to‐noise ratio of 3). Intra‐day (n = 11) and inter‐day (n = 6) coefficients of variation were better than 11.2%. The assay was successfully applied to control (n = 134) and glutaric acidemia type 1 (n = 55) urine samples. Copyright © 2007 John Wiley & Sons, Ltd.
‘Divine unknowing’: lessons from the Christian mystical tradition for healthcare today
Authors: Tyler Peter M. 
Published: May 2007

AbstractThe article explores the hermeneutic of taking five key facilitating attitudes of the Christian mystical tradition and seeing their relevance to healthcare, pastoral care and psychotherapy/counselling today. The five attitudes are Contemplation, Embodiment, Openness, Integration and Discernment. Each is discussed in turn, drawing on their origins in classical Christian sources and their relevance to contemporary practice. The author argues that in a time of potentially lethal religious conflict they offer an alternative vision of spiritual care. Copyright © 2007 John Wiley & Sons, Ltd.
Closed Form Solutions to Dynamic Punch Problems by Integral Transform Method
Authors: Dhaliwal R. S. , Singh B. M. 
Published: May 2007

AbstractIn this paper we have used integral transform method to obtain a closed form solution of dynamical mixed boundary value problems. We consider an elastic layer with one face lying on a rigid foundation and the other face with two moving punches. Two particular cases of this general problem are considered in detail. The solution for each problem is reduced into triple integral equations with trigonometrical kernel. We have obtained closed form solutions of each set of triple integral equations and closed form expressions for shear stress and contact pressure.
Zur analytischen Lösung geometrischer Optimierungsaufgaben mittels Dualität bei Steuerungsproblemen. Teil I
Authors: Andrejewa J. A. , Klötzler R. 
Published: May 2007

AbstractAuf der Grundlage der Dualitätstheorie bei Steuerungsproblemen werden Optimalitätskriterien entwickelt und unter Verwendung von Stützfunktionen auf einige geometrische Optimierungsprobleme angewandt. Im ersten Teil steht zur Diskussion die analytische Bestimmung ebener konvexer Bereiche vorgegebener Dicke und vorgegebenen Durchmessers mit maximalen bzw. minimalem Umfang.
Dualität und Strafmethoden bei elliptischen Differentialgleichungen
Authors: Grossmann Ch. 
Published: May 2007

AbstractBased on a quite general theory for deriving convergence bounds in penalty methods we derive estimations for the influence of penalty and discretization parameters in elliptic differential equations with Dirichlet boundary conditions. Furthermore, starting from an analysis of Brezzi's condition within the framework of optimization some modification of the penalty technique in linear problems is proposed. This modification leads to an improved convergence.
Kinetic Theory of a Gas with Internal Degrees of Freedom
Authors: Jehring L. 
Published: May 2007

AbstractApplying the moment method of H. Grad, a closed set of balance equations for density, momentum, angular momentum, stress and couple‐stress tensor, and heat flux is derived for a rarefied gas composed of non‐rigid dumb‐bell shaped particles. Averaging these equations over all values of size and orientation of the particles yields new balance equations governing the gas if the structure of the particles changes essentially faster than the position of their centres of mass. In a limiting case the volume viscosity is given in terms of the collision frequency.
Remarks on a One‐Dimensional Stefan Problem Related to the Diffusion‐Consumption Model
Authors: Comparini E. , Ricci R. , Tarzia D. A. 
Published: May 2007

AbstractWe study the behaviour of the free boundary of the Crank‐Gupta model for the diffusion‐consumption of oxygen in a living tissue, assuming an initial condition corresponding to the stationary solution and with a decreasing input of oxygen at the fixed boundary.
Über Korrelationen von Skalaren in homogener isotroper Turbulenz
Authors: Szablewski W. 
Published: May 2007

AbstractEs wird die Existenz eines Ähnlichkeitsgesetzes für die skalare Zweipunktkorrelation zweiter Ordnung im Trägheits‐Konvektionsbereicht r≪l (l Maß für die Breite der Geschwindigkeits‐ und Skalar‐Korrelation) hergeleitet. Auf der Grundlage des Ähnlichkeitsgestzes, hergeleitet vom Verf. in einer vorangehenden Arbeit, für das skalare Spektrum im Trägheits‐Konvektionsbereich k≫k0 (k0 Wellenzahl der Großen Wirbel) wird für mittlere Prandtlzahlen der Verlauf der skalaren Zweipunktkorrelation zweiter Ordnung und der gemischten (Skalar‐Geschwindigkeit) Zweipunktkorrelation dritter Ordnung mittels Integralrelationen approximative ermittelt. Es ergibt sich eine Ähnlichkeitsstruktur für die Korrelationen. Vergleich mit Messungen.
On the Helmholtz‐Kirchhoff Flow Past an Upstream Facing N‐Segment Channel
Authors: Bentwich M. , Haselgrove M 
Published: May 2007

AbstractThe two dimensional irrotational flow past an upstream facing channel is analysed assuming that an infinitely‐long constant‐pressure cavity trails behind it. The ‘wet’ surface consist of N straight segments of arbitrary lengths which form arbitrary angles one with the other. A dividing streamline emanates upstream and branches at a stagnation point on the wet surface. It is assumed that the two branches separate from the wet surfaces at the outer edges of the first and Nth segments.Numerical results are obtained for a rectangular channel i. e. N = 3, both angles of π/2 and the two extreme segments of equal lengths. The calculations show that the hydrodynamic pressure gives rise to a moment which tends to position the channel so that its outer flanks are parallel to the free stream.
A Perturbation Method for the Analysis of Torsion of a Compressible Hyperelastic Cylinder
Authors: Tait R. J. , Haddow J. B. 
Published: May 2007

AbstractA regular perturbation method for the analysis of finite torsion and extension of a compressible isotropic hyperelastic cylinder is proposed. The method is outlined for a particular class of strain energy functions although it can be extended to other classes with some additional complication. Results are obtained for a particular strain energy function for which certain other methods are not applicable and for which a previously proposed perturbation method [1] was unsuccessful. It is assumed that, although the torsion and possibly extension are finite, they are such that the volume strain can be considered infinitesimal. A motivation for the procedure is to examine the behavior of the cylinder as the compressibility of the material approaches zero. Numerical results are given for two different strain energy functions.
Dissipative Rigids in Gyrodynamics
Authors: Rimrott F. P. J. 
Published: May 2007

AbstractExperimental evidence, from spacecraft behaviour, has shown that the concept of an absolutely rigid body, which has served us so well in the past, apparently no longer suffices to provide for the theoretical treatment of all problems settings in solid mechanics. The purpose of the present paper is to demonstrate that the introduction of a dissipative rigid as a fundamental concept into theoretical mechanics has become a necessity.Using data from a disabled spacecraft, the paper begins by describing the attitude decay of a gyroscope in detail, using the concept of a dissipative rigid, and its dissipation power, for the theoretical treatment. Against this background, the case for the dissipative rigid body is made in general terms. Each relation bears re‐deriving, and those affected are presented in their new form.While the concept of a dissipative rigid body is quite general, it can be shown to play a role in gyrodynamics (including impact studies, where it is well established only, a conclusion that explains why its general introduction had to wait until after the advent of the space age.
Lokalisierung der Lösung diskreter Systeme mit instationärer periodischer Nichtlinearität
Authors: Leonow G. A. , Reitmann V. 
Published: May 2007

AbstractIn der vorliegenden Arbeit wird mit der Methode der invarianten Kegel das Stabilitätsverhalten im Sinne von YU. A. Bakaev [1] von diskret wirkenden nichtautonomen Phasensystemen untersucht. Zu den betrachteten Phasensystemen gehören Systeme der automatischen Steuerung mit unstetigen Nichtlinearitäten, die periodisch sind. Mit Hilfe des in der Arbeit bewiesenen Frequenzkriteriums zur asymptotischen Eingrenzung der Phasendifferenz werden Fangregime eines einfachen Impuls‐ und eines Ziffernsystems der Phasensynchronisation analysiert. Diese Vorgehensweise erlaubt von einem einheitlichen Standpunkt aus die explizite Angabe der Attraktoren von Abbildungen der Kreisperipherie in sich, von unstetigen Poincaré‐Abbildungen, wie sie beim Lorenz‐System der konvektiven Turbulenz auftreten, von Punkt‐Mengen‐Abbildungen und von anderen Abbildungsklassen. Der Zusammenhang mit der Chaos‐Theorie wird an einem Beispiel demonstriert.
Zur Effektivität des Verfahrens der monotonen Iteration bei semilinearen parabolischen und elliptischen Randwertproblemen
Authors: Carl S. 
Published: May 2007

AbstractDie Effektivität des Verfahrens der monotonen Iteration wird in Abhängigkeit eines bestimmten Iterationsparameters untersucht. Im Ergebnis erhält man mit kleiner werdendem Iterationsparameter eine effektivere Iteration. Der zulässige Bereich für den Iterationsparameter wird angegeben.
Über ein System mit nichtlinearer Parametererregung und Fremderregung
Authors: Tondl A. 
Published: May 2007

AbstractEin System mit nichtlinearer Parametererregung und Fremderregung wird analysiert, bei dem die nichtlineare Parametererregung durch das Produkt der Auslenkungskoordinate, ihrer Geschwindigkeit und der harmonischen Funktion gegeben ist. Stationäre Schwingungen in der Hauptresonanz und ihre Stabilität im Großen werden analysiert.
Free Convection in an Infinite Porous Medium Due to a Pulsating Point Heat Source
Authors: Purushothaman R. , Ganapathy R. , Hiremath P. S. 
Published: May 2007

AbstractNatural convection flow and heat transfer induced by a pulsating point heat source, embedded in an unbounded fluid‐saturated porous medium is studied analytically. Solutions for both the velocity and temperature fields are obtained in the form of series expansions in the Rayleigh number based on the permeability of the porous medium and the mean heat generation rate from the source. All discussions are based on the assumption that the flow is governed by Darcy's law and that the thermal Rayleigh number is small. The fluctuating part shows the evolution of different wave patterns. The interaction of the first harmonic fields induce second‐order mean components in the velocity and temperature fields. Analytical expressions are obtained for the second‐order mean in both the velocity and temperature fields.
On the Decoupling and the Solutions of the Euler Dynamic Equations Governing the Motion of a Gyroscope
Authors: Panayotounakos D. E. , Theocaris P. S. 
Published: May 2007

AbstractThe decoupling and the solutions of the three strongly nonlinear ordinary dynamic differential equations, governing the motion of an arbitrary rigid body, free to rotate about a fixed point (gyro), are presented. The theory developed is based on the assumption that the instantaneous angular velocity and the moment‐components are arbitrary smooth functions of the time. By a quantitative analysis, analytical solutions of the resulting differential equations were obtained under some general conditions in accordance with the physical problem. Finally, a theoretical application is investigated concerning the dynamic response of a one‐axis symmetrical gyroscope subjected to an arbitrary external loading.