bluuebunny/crossref_metadata_2025_split huggingface dataset:
Three‐dimensional water diffusion in impermeable cylindrical tubes: theory versus experiments
Authors: Avram Liat , Özarslan Evren , Assaf Yaniv , Bar‐Shir Amnon , Cohen Yoram , Basser Peter J. 
Published: June 2008

AbstractCharacterizing diffusion of gases and liquids within pores is important in understanding numerous transport processes and affects a wide range of practical applications. Previous measurements of the pulsed gradient stimulated echo (PGSTE) signal attenuation, E(q), of water within nerves and impermeable cylindrical microcapillary tubes showed it to be exquisitely sensitive to the orientation of the applied wave vector, q, with respect to the tube axis in the high‐q regime. Here, we provide a simple three‐dimensional model to explain this angular dependence by decomposing the average propagator, which describes the net displacement of water molecules, into components parallel and perpendicular to the tube wall, in which axial diffusion is free and radial diffusion is restricted. The model faithfully predicts the experimental data, not only the observed diffraction peaks in E(q) when the diffusion gradients are approximately normal to the tube wall, but their sudden disappearance when the gradient orientation possesses a small axial component. The model also successfully predicts the dependence of E(q) on gradient pulse duration and on gradient strength as well as tube inner diameter. To account for the deviation from the narrow pulse approximation in the PGSTE sequence, we use Callaghan's matrix operator framework, which this study validates experimentally for the first time. We also show how to combine average propagators derived for classical one‐dimensional and two‐dimensional models of restricted diffusion (e.g. between plates, within cylinders) to construct composite three‐dimensional models of diffusion in complex media containing pores (e.g. rectangular prisms and/or capped cylinders) having a distribution of orientations, sizes, and aspect ratios. This three‐dimensional modeling framework should aid in describing diffusion in numerous biological systems and in a myriad of materials sciences applications. Copyright © 2008 John Wiley & Sons, Ltd.
Mechanical characteristics of hydrogenated natural rubber vulcanizates
Authors: Ikeda Yuko , Phinyocheep Pranee , Kittipoom Sumet , Ruancharoen Jareerat , Kokubo Yota , Morita Yuichi , Hijikata Kensuke , Kohjiya Shinzo 
Published: June 2008

AbstractMechanical properties of partially hydrogenated natural rubber (HNR) vulcanizates were evaluated regarding their chemical structure and crystallizable nature of HNR, and are reported here, to the best of our knowledge, for the first time. HNRs of three levels of hydrogenation (20.6, 29.0, and 40.6 mol%) were successfully prepared by the chemical modification of natural rubber (NR) latex using N2H4 and H2O2 as reagents, in a sufficient amount for preparing sulfur‐crosslinked samples to be subjected to mechanical and structural measurements. The three HNR vulcanizates were found to be crystallizable upon stretching; it is noted that even 40.6 mol% hydrogenation did not prevent HNR vulcanizates from crystallization upon stretching, while their onset strain of crystallization was higher than that of NR vulcanizate. The hysteresis loss and residual strain up to a stretching ratio of 2 for the HNR vulcanizates tended to become larger with the increase in the degree of the hydrogenation. Tensile and dynamic mechanical properties of 20.6 mol% hydrogenated HNR vulcanizate were comparable to those of NR vulcanizate. From differential scanning calorimetry and temperature dispersion of dynamic modulus or loss, the glass transition temperatures of HNR vulcanizates were found to be almost the same as that of NR vulcanizate, which is also notable. The thermal stability of HNR vulcanizates was better than that of NR vulcanizate. Thus, this chemical modification seems to give a promising NR derivative whose properties can be equivalent or even better than the mother polymer. Copyright © 2008 John Wiley & Sons, Ltd.
Curing kinetics of the epoxy system diglycidyl ether of bisphenol A/isophoronediamine by Fourier transform infrared spectroscopy
Authors: Fraga Francisco , Vazquez Eva C. , Rodríguez‐Núñez Eugenio , Martínez‐Ageitos José Manuel 
Published: June 2008

AbstractThe curing reaction of an epoxy system consisting of a diglycidyl ether of bisphenol A (BADGE, n = 0) and isophoronediamine (IPD), was studied by Fourier transform infrared spectroscopy (FTIR). The degree of conversions and the reaction rates at different isothermal curing temperatures were calculated from the infrared spectra using a method derived from Beer's law. This method is based on the ratio of the height of the characteristic absorbance peak to reference absorbance peak. A kinetic model proposed by Sourour and Kamal has been used to fit experimental data. Copyright © 2008 John Wiley & Sons, Ltd.
α1‐Adrenozeptor‐Antagonisten. Bei BPS und Hypertonie
Authors: Haubold  , Hein Lutz 
Published: June 2008

Abstractα1‐Antagonisten sind sehr wirksame Pharmaka für die Kombinationstherapie der Hypertonie sowie für die symptomatische Behandlung des benignen Prostatasyndroms. Weitere klinische und klinisch‐experimentelle Untersuchungen sind nötig, um zum einen den Mechanismus und exakten Wirkort dieser Arzneistoffe beim Prostatasyndrom aufzuklären. Zum anderen werden neu entwickelte Substanzen zeigen müssen, ob sich aus der Selektivität für einen oder zwei Rezeptorsubtypen ein klinischer Vorteil ergibt.
Arterielle Hypertonie – was gibt es Neues? Therapie einer Volkskrankheit
Authors: Fiedler Martin 
Published: June 2008

AbstractDie arterielle Hypertonie ist eine Volkskrankheit. Trotz Verbesserung der Versorgungssituation ist die Dunkelziffer nicht erkannter Hypertoniker in Deutschland noch zu hoch und die Implementierung aktueller Leitlinien in die Diagnostik und Therapie der Patienten unbefriedigend. Die aktuellen Leitlinien der DHL 2005 und ESH/ESC 2007 sehen als Grundlage der Therapiestrategie nicht allein die exakt ermittelte Höhe des Blutdrucks, sondern fokussieren vielmehr auf die Beurteilung des individuellen kardiovaskulären Gesamtrisikos der Patienten. Daher spielt die exakte Erfassung von zusätzlichen kardiovaskulären Risikofaktoren, hypertensiven Endorganschäden und Begleiterkrankungen eine ganz entscheidende Rolle. In den ESH/ESC‐Leitlinien 2007 wurde das metabolische Syndrom in seiner Bedeutung als Risikofaktor dem Diabetes mellitus gleichgesetzt. Bei der Behandlung von Patienten mit einer Hypertonie Grad 2 und 3, einem hohen kardiovaskulären Risiko und niedrigem Zielblutdruck sollte bereits zu Beginn der Behandlung eine “Kombinationstherapie” erwogen werden. In der Differentialtherapie besteht für ACE‐Hemmer und Angiotensinrezeptor‐Antagonisten eine neue Indikation in der Prävention des Vorhofflimmerns und des Diabetes mellitus Typ‐2.Während α‐Blocker bereits ihre Position als Antihypertensiva der ersten Wahl verloren haben, wird gegenwärtig auch die Bedeutung der β‐Blocker in der initialen Therapie der primären Hypertonie kritisch diskutiert. Dies ist vor allem auf die schlechten Ergebnisse bei der Schlaganfallsprävention zurückzuführen. Darüber hinaus erhöhen β‐Blocker und Thiazide das Diabetesrisiko. Insbesondere Thiazide scheinen über eine therapieassoziierte Hypokaliämie die Insulinsekretion negativ zu beeinflussen. Der klinische Stellenwert von Askiren, einem neuen oral verfügbaren Renin‐Antagonisten, muss erst im Rahmen klinischer Studien genauer definiert werden.
Using video analysis to illuminate professional–patient interaction of clinical interventions
Authors: Virta Lena , Eriksson Rikard 
Published: June 2008

AbstractEvidence‐based practice in physiotherapy should include reasoning as well as definition of practice knowledge and manual skills. The aim of this study was to explore how patients and physiotherapist interact in a situation of motor learning. Six patients with the diagnosis of subacromial impingement were video‐filmed during 11 treatment sessions with the same physiotherapist. The aim of the treatment was to improve their initial pattern of movement in arm elevation. The films were analysed with content analysis and the results are presented in three content areas: the context, interaction and professional skills. Further development of methodology, including computer aids for transcriptions, will make digital video analysis an interesting research method for physiotherapists. Copyright © 2008 John Wiley & Sons, Ltd.
Interconnection of the parameters obtained from the dielectric spectrum of CaF2 doped with ErF3 and YbF3
Authors: Vassilikou‐Dova Aglaia , Katsika‐Tsigourakou Vassiliki 
Published: June 2008

AbstractA model has been suggested long ago that interconnects point defect parameters with bulk properties. On this basis, the ra‐tio of the migration entropy sm and the migration enthalpy hm should be equal to a bulk quantity. The validity of this prediction is studied here for the migration sm deduced from the pre‐exponential factor τ0 over the activation energy E involved in the Arrhenius relation τ = τ0 exp (E /kT) for the relaxation time τ. The study is focused on the so called RI‐relaxation in CaF2 doped with ErF3 and YbF3. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical study of static and dynamic properties of orthorhombic multiferroic substances
Authors: Wesselinowa J. M. , Georgiev I. 
Published: June 2008

AbstractThe influence of the magnetoelectric coupling and the exchange interaction constants on different magnetic and dielectric properties of orthorhombic RMn2O5 multiferroic materials is studied based on the transverse Ising and Heisenberg models using a Green's function technique. In the vicinity of the phase transition temperature TC we obtain an anomaly, a kink in the temperature dependence of the magnetic properties. This is due to the coexistence of ferroelectricity and magnetism which leads to interplay between the electric and magnetic properties. The spin excitations show a novel softening around TC due to the magnetoelectric coupling. The effect of external electric and magnetic fields is also calculated. We obtain the magnetic‐field‐induced polarization and the electric‐field‐induced magnetization. The obtained results are in qualitative agreement with the experimental data. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of magnetization processes using higher harmonic ac‐susceptibility
Authors: Prüfer S. , Ziese M. 
Published: June 2008

AbstractThe ac‐susceptibility of a La0.7Sr0.3MnO3 epitaxial film was measured up to the 11th harmonic as a function of ac‐field amplitude, superimposed dc‐field and temperature. The experimental data reflect the magnetization hysteresis‐loop shape in a very precise and detailed way. This is further elucidated by numerical simulations of the ac‐susceptibility within a Preisach model with Gaussian distribution function. Using parameters from magnetization measurements the simulated ac‐susceptibility curves were found to be in good agreement with the experimental results. This shows that measurements of higher harmonic susceptibilities are a powerful tool for the precise study of magnetization processes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microcrystalline silicon‐carbon alloys as anti‐reflection window layers in high efficiency thin film silicon solar cells
Authors: Chen Tao , Huang Yuelong , Yang Deren , Carius Reinhard , Finger Friedhelm 
Published: June 2008

AbstractMicrocrystalline silicon‐carbide (μc‐SiC:H) films were prepared using hot wire chemical vapor deposition at low substrate temperature. The μc‐SiC:H films were employed as window layers in microcrystalline silicon (μc‐Si:H) solar cells. The short‐circuit current density (JSC) in these n‐side illuminated n–i–p cells increases with increasing the deposition time tW of the μc‐SiC:H window layer from 5 min to 60 min. The enhanced JSC is attributed to both the high transparency and an anti‐reflection effect of the μc‐SiC:H window layer. Using these favourable optical properties of the μc‐SiC:H window layer in μc‐Si:H solar cells, a JSC value of 23.8 mA/cm2 and cell efficiencies above 8.0% were achieved with an absorber layer thickness of 1 μm and a Ag back reflector. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nitric acid oxidation on carbon dispersion and suspension stability
Authors: Zhang Ning , Wang Liu‐yan , Liu Hao , Cai Qing‐Kui 
Published: June 2008

AbstractIn this study, we have investigated the effect of nitric acid oxidation on the dispersion and suspension stability of activated carbon powder. We treated activated carbon powder with nitric acid at different concentrations. We measured the content of functional groups, the zeta potential and the powder particle size of the activated carbon powder with the Boehm titration, Fourier transform infrared spectroscopy, a zeta potential analyzer, and scanning electron microscopy. The results show that with the increase of nitric acid molar concentration, the content of acid functional groups increased, whereas the content of alkali functional groups decreased. At a nitric acid concentration of 10 mol/l, the surface‐modified activated carbon powder displays features such as the highest functional group content and zeta potential value, the smallest particle size, and the best dispersion and suspension stability in the solution. Copyright © 2008 John Wiley & Sons, Ltd.
Orientation‐dependent surface composition of in situ annealed strontium titanate
Authors: Zagonel Luiz F. , Barrett Nicholas , Renault Olivier , Bailly Aude , Bäurer Michael , Hoffmann Michael , Shih Shao‐Ju , Cockayne David 
Published: June 2008

AbstractThe surface composition of polycrystalline niobium‐doped strontium titanate (SrTiO3: Nb) is studied using X‐ray photoelectron emission microscopy (XPEEM) for many grain orientations in order to characterise the surface chemistry with high spatial resolution. The surface sensitivity is maximised by the use of soft X‐ray synchrotron radiation (SR). The grain orientation is determined by electron backscattering diffraction (EBSD). Stereographic plots are used to show the correlation between surface composition and orientation for several grains. Predominant surface terminations are assigned to major orientations. Copyright © 2008 John Wiley & Sons, Ltd.
Surface characteristic of poly(p‐phenylene terephthalamide) fibers with oxygen plasma treatment
Authors: Wang Jing , Chen Ping , Li Hong , Li Wei , Wang Baichen , Zhang Chengshuang , Ni Ren 
Published: June 2008

AbstractOxygen plasma is widely employed for modification of polymer surfaces. Plasma treatment process is a convenient procedure that is also environmentally friendly. This study reports the effects of oxygen plasma treatment on the surface properties of poly(p‐phenylene terephthalamide) (PPTA) fibers. The surface characteristics before and after oxygen plasma treatment were analyzed by XPS, atomic force microscopy (AFM) and dynamic contact angle analysis (DCAA). It was found that oxygen plasma treatment introduced some new polar groups (OCO) on the fiber surface, increased the fiber surface roughness and changed the surface morphologies obviously by plasma etching and oxidative reactions. It is also shown that the fiber surface wettability was improved significantly by oxygen plasma treatment. Copyright © 2008 John Wiley & Sons, Ltd.
Microstructural characteristics of Ce conversion coatings on Cf/Al composite or NiP plated Cf/Al composite
Authors: Wang Chunyu , Xiu Ziyang , Zhang Qiang , Wu Gaohui 
Published: June 2008

AbstractThe microstructural characteristics of Ce conversion coatings on carbon fiber reinforced Al matrix (Cf/Al) composites and Ce conversion coatings on NiP plated Cf/Al composites were studied by SEM, AFM, TEM and XPS. The Ce conversion coating on the NiP plated composite does not have obvious microcracks, which can be found easily in Ce conversion coatings. The Ce conversion coating on NiP plated composite has a lower surface roughness profile arithmetic mean deviation (Ra) than Ce conversion coating, as seen by AFM. Because of the inhomogeneity of the material surface and the different levels of deposition of Ce conversion coatings at the different sites, nonhomogeneous sites would promote microcrack formation of the Ce conversion coatings. The Cf/Al composite surface has lessuniformity than NiP plated composite, leading to more prominent microcracks. Selected area electron diffraction (SAED) patterns of Ce conversion coating could not be indexed nor matched closely to any of the oxides (Ce2O3, Ce7O12, Ce6O11) or hydroxides (Ce(OH)3) that are listed in the Powder Diffraction File maintained by Diffraction Data, but for Ce conversion coating on the NiP plated composite the data matched closely with that of CeO2 or Ce6O11. The XPS results showed that the Ce conversion coating mainly contained both Ce3+ and Ce4+ species, but Ce4+ species were the dominant oxidation state on NiP coating with Ce conversion deposition. Copyright © 2008 John Wiley & Sons, Ltd.
The Role of Aromaticity and the π‐Conjugated Framework in Multiporphyrinic Systems as Single‐Molecule Switches
Authors: Lee Sang Uck , Belosludov Rodion V. , Mizuseki Hiroshi , Kawazoe Yoshiyuki 
Published: June 2008

AbstractA systematic analysis of electron‐transport characteristics for monomer, dimer, and tetramer multiporphyrinic systems is presented, to provide a thorough understanding of the structural dependence of electron transport related to the aromatic nature of the contact structure. Theoretical investigation shows that the electron‐transport characteristics can be controlled by manipulating the π‐conjugated framework in the multiporphyrinic systems through the arrangement of the inner hydrogen atoms. The designed π‐conjugated framework assigns the distinct aromaticity on the contact structure, and the large aromatic nature of the contact structure increases conductivity. The feature emerging from this study is that the aromaticity and π‐conjugated framework are important factors that control the electron‐transport characteristics in molecular‐scale electronic devices, such as single‐molecule switches.
Gas chromatographic‐mass spectrometric analysis of isoprenoid hydrocarbons and fatty acids in shark liver oil products
Authors: Gelpi E. , Oro’ J. 
Published: June 2008

AbstractThe liver oil from the South American Basking shark has been fractionated by silica gel chromatography and analyzed by the new method of combined gas‐chromatography mass spectrometry. The major compounds of the nonsaponifiable fraction are pristane and squalene, which account for 7.6 and 31.3% of the oil. The saponifiable fraction contains normal fatty acids from C14 to C22; the four major components are palmitic, oleic, and the monounsaturated eicosenoic and docosenoic acids. No correlation was observed between the hydrocarbons (essentially all isoprenoid derivatives) and the fatty acids (essentially all normal) of this oil.The same treatment was applied to a sample of commercial pristane which was obtained from Basking shark liver oil. It was found to contain about 1% phytane and small amounts of octadecane, nonadecane, and methyl and ethyl palmitates. Mass spectral data for squalene are presented for the first time along with the low electron energy‐mass spectra for pristane and phytane.
Preparation and evaluation of surface‐active brassylic acid‐ethylene oxide adducts
Authors: Miwa Thomas K. , Madrigal Richard V. , Tallent William H. , Wolff Ivan A. 
Published: June 2008

AbstractBoth liquid and solid surface‐active adducts of brassylic (tridecanedioic) acid were prepared by potassium hydroxide‐catalyzed addition of ethylene oxide gas to the molten acid. The number‐average molecular weights of the adducts ranged from 500 to 3,000. These adducts cover a wide span in the ratios of hydrophilic to lipophilic portions of the molecule. They are unique in that hydrophilic end‐groups sandwich a rather long chain of lipophilic methylene units. Treatment of some adducts with hot, saturated, aqueous sodium chloride induced transesterification and produced hydroxyl‐terminated, multi‐brassylic, poly(ethylene glycol) esters of MWn 1,000 to 4,000, all of which were efficient surface‐active agents.Average degrees of polymerization of the poly(ethylene oxide) (PEO) chains were determined by a) functional group analysis, b) weight increase, and c) methanolysis of the products, followed by gas‐chromatographic analysis of the isolated poly(ethylene glycol) fraction. Surface tension, critical micelle concentration, emulsion stability, and efficiency as an emulsifying agent in the aqueous polymerization of vinyl acetate were measured to evaluate surfactant properties of products in which the degrees of polymerization of the PEO chains ranged from 1.4 to 44.
Isomerization during hydrogenation of soap. I. Potassium oleate
Authors: Raju D. S. , Subbaram M. R. , Achaya K. T. 
Published: June 2008

AbstractPotassium oleate in slightly alkaline solution was hydrogenated for up to 7 hr with Rufert nickel catalyst at 150C and 20 kg/sq cm pressure. With 1% catalyst, the iodine value dropped by 12 units in the first hour, and only slightly thereafter. With 2% catalyst there was a drop of 24 units in iodine value in the first hour, a steady state for the next 3 hr, and a second sharp drop of 30 units prior to the seventh hour. Samples of fat hydrogenated over 1% catalyst for 3 hr and 7 hr respectively were analyzed by gas‐liquid chromatography, thecis andtrans monoenes were separated by argentation thin‐layer chromatography, and the positional isomers in each were determined by oxidation of the total fraction to dicarboxylic acids, which were then estimated by GLC.Apart from double‐bond saturation during the first 3 hr of hydrogenation, extensive double‐bond migration yielded 23.5% oftrans 8‐ to 13‐monoene, accompanied by small amounts only of positionalcis monoenes other than the starting material. After 7 hr of hydrogenation, extensivecis tocis isomerization occurs, accompanied by lesscis totrans shift; thecis:trans ratio for each monoene consequently tended toward 1:1. The results are explained on the sorption mechanism of hydrogenation and suggest that soap hydrogenation, involving catalyst poisoning, may represent a magnified version of normal fat hydrogenation.
New process for the production of better‐quality rapeseed oil and meal. I. Effect of heat treatments on enzyme destruction and color of rapeseed oil
Authors: Eapen K. E. , Tape N. W. , Sims R. P. A. 
Published: June 2008

AbstractThe thioglucosides (which are precursors of toxic principles) and the fibrous hulls of rapeseed are the two major factors which limit the utilization of rapeseed meal as a protein supplement in human foods. In commercial practice the enzyme responsible for the liberation of toxic principles from thioglucosides is destroyed by a dry‐heat treatment, but no attempt is made to remove the thioglucosides or the fibrous matter from the meal. The new wet‐heat method of processing to inactivate myrosinase also results in the production of an improved quality of oil. In this paper the advantages of a wet‐heat treatment in processing rapeseed are discussed.