bluuebunny/crossref_metadata_2025_split huggingface dataset:
Migration and blooming of waxes to the surface of rubber vulcanizates
Authors: Nah S. H. , Thomas A. G. 
Published: August 2005

AbstractWhen certain substances, notably waxes, are incorporated into rubber during vulcanization, the surface of the vulcanized rubber may subsequently become covered by a film of the substance diffusing out. This phenomenon, known as blooming, depends on the substance being soluble at the vulcanization temperature but only partially soluble at the temperature of blooming. A study has been made using pure waxes in natural rubber vulcanizates with a range of crosslink densities. The mass of bloomed material has been determined as a function of time, and the expected dependence on the square root of the time has been found to hold over the anticipated range. It has been shown that the kinetics of the process cannot be explained simply in terms of the degree of supersaturation of the wax in the rubber, the observed rates being much too low. This appears to be related to the precipitation of the wax in the body of the material. A theory has been developed based on a calculation of the stresses set up around such a precipitated particle and the effect of the consequent free‐energy gradient on the rate of diffusion. Comparison with experiment shows satisfactory agreement with the theory.
Polydispersity effects and the interpretation of polymer adsorption isotherms
Authors: Stuart M. A. Cohen , Scheutjens J. M. H. M. , Fleer G. J. 
Published: August 2005

AbstractIn many cases, polymer adsorption is studied by measuring adsorption isotherms. Quite often it is found that the results are at variance with theoretical predictions. However, usually these adsorption isotherms are interpreted in terms of a single polymeric solute. Most polymers used in experimental studies are polydisperse and should be treated as mixtures. It is well established that the larger molecules in such mixtures adsorb preferentially over the smaller ones. In this paper we show that many discrepancies between polymer adsorption theory and experiment (e.g., the rounded shape of isotherms, the dependence of the adsorbance on adsorbent concentration, and the lack of desorption upon dilution) can be attributed to polydispersity. A quantitative analysis enables us to calculate isotherms for a polymer of arbitrary molecular weight distribution, provided the dependency of the plateau adsorbance on molecular weight is known. Experiments supporting the theory are reported. The fact that polymers do not desorb upon dilution with solvent is often regarded as a proof that polymer adsorption is irreversible. We show that, if a polydisperse sample is in equilibrium with an adsorbing surface, no detectable desorption may take place upon dilution. Therefore, the adsorption of polymers might well be reversible, even if desorption experiments would indicate apparent irreversibility.
Anisotropy of dielectric relaxation in crystal form II of poly(vinylidene fluoride)
Authors: Miyamoto Yoshihisa , Miyaji Hideki , Asai Kenjiro 
Published: August 2005

AbstractThe anisotropy of the crystalline relaxation (α relaxation) in oriented poly(vinylidene fluoride) in crystal form II has been studied. The dielectric increment Δε is analyzed on the basis of the two‐site model. A linear relation between Δε/χξ and cos2θ is obtained, where χ is the degree of crystallinity, ξ is the ratio of the internal field to the applied field, and θ is the angle between the applied electric field and the molecular axis. The dipole moment changes direction only along the molecular axis in the relaxation in crystal form II; the molecular motion cannot be explained by chain rotation around the molecular axis. Possible models for the α relaxation are proposed: change in conformation with internal rotation can occur in the crystalline chains, and defects in the crystalline regions play an important role in the α relaxation.
Properties of solution‐grown crystals of fractions of isotactic polypropylene with different degrees of stereoregularity
Authors: Martuscelli Ezio , Pracella Mariano , Zambelli A. 
Published: August 2005

AbstractSolution‐grown crystals of fractions of isotactic polypropylene (IPP) with different degrees of stereoregularity have been obtained by isothermal crystallization from α‐chloronaphthalene, using a self‐seeding technique. Electron micrographs of samples, crystallized under the same undercooling, show that, with decreasing fraction of isotactic pentads, the perfect rectangular shape of the single crystal is lost and the presence of more complex morphologies is increasingly observed. The equilibrium dissolution temperature Td of IPP fractions, from polymers prepared with a titanium based catalyst, decreases linearly with decreasing percentage of isotactic pentads. An extrapolated value of 171°C is obtained for the equilibrium dissolution temperature of a crystal of IPP with 100% isotactic pentads, i.e., an IPP crystal free of configurational defects. The melting temperature T′m and the apparent enthalpy of fusion ΔH of crystallized and annealed crystal aggregates have been determined by differential calorimetry. The equilibrium melting temperature Tm also depends greatly upon the isotactic pentad concentration. For 100% concentration the extrapolated value of Tm is 181°C. Tm decreases about 1°C per 1% decrease in the isotactic pentad population. The observed equilibrium melting and dissolution temperature depression does not follow the predictions of the Flory equation for copolymer crystallization. In fact, the effect of decreasing probability of isotactic sequence propagation is to depress Td and Tm much more rapidly. The apparent enthalpy of fusion of both solution‐grown crystals and melt‐recrystallized samples decreases with an increase in the number of configurational impurities along the chain. For the most stereoregular fraction the average length of isotactic stereoblocks has been compared with the lamellar thickness of solution‐grown lath‐shaped single crystals.
Crystallization characteristics of polymer blends. I. Polyethylene and polystyrene
Authors: Aref‐Azar Ahmad , Hay James N. , Marsden Brian J. , Walker Neil 
Published: August 2005

AbstractBlends of polyethylene and polystyrene have been prepared to study the effect of the morphology on their crystallization characteristics since the polymers are known to phase separate. The polymer component present in least amount formed a dispersed phase of discrete spherical particles whose number and size altered with blend composition. However, close to 50% composition cylindrical rods of polyethylene dispersed in polystyrene were observed. With polyethylene in excess the kinetics of crystallization were insensitive to the morphology, but with polyethylene present as the dispersed phase they became dependent on the size and number of the spheres, and in particular on the nucleation density. When the number of spherical particles exceeded that of heterogeneous nuclei, larger supercoolings, and so presumably homogeneous nucleation, were required for crystallization to develop further. The degree of crystallization of the blends then became dependent on the temperature of crystallization rather than on time, and the isothermal crystallization appearing to be instantaneous.
Effects of heat and pressure on intercalation structures of isobutylene‐isoprene rubber/clay nanocomposites. I. Prepared by melt blending
Authors: Liang Yu‐Rong , Ma Jun , Lu Yong‐Lai , Wu You‐Ping , Zhang Li‐Qun , Mai Yiu‐Wing 
Published: August 2005

AbstractIn this work, the effects of heat and pressure on intercalated structures of isobutylene‐isoprene rubber/clay nanocomposites (IIRCNs) prepared by melt blending were investigated. Not only the local intercalated structures were monitored by wide‐angle X‐ray diffraction, but also the spatial distributions of intercalated structures were observed by transmission electron microscope. The experimental result reveals that the intercalated structures and their spatial distributions in the matrix are extensively altered by the thermal treatment at atmospheric or higher pressure. The possible microstructural models for untreated and treated IIRCNs were put forward. The observed phenomena were interpreted from the viewpoints of thermodynamics and kinetics theories as well as the feature of rubber. Finally, guidelines were proposed for designing curing system to achieve desired intercalated/exfoliated morphology. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2653–2664, 2005
Characterization of ZnO/diamond SAW devices elaborated on the smooth nucleation side of MPACVD diamond
Authors: Le Brizoual L. , Lamara T. , Sarry F. , Belmahi M. , Elmazria O. , Bougdira J. , Remy M. , Alnot P. 
Published: August 2005

AbstractWe designed a SAW filter in this work by combining the piezoelectric ZnO film with a freestanding double layer diamond film deposited using CH4–H2 pulsed MPACVD process through two growth stages. The AFM measurements on the nucleation side of the diamond film has shown that this side is smooth enough to perform photolithography process in the SAW device elaboration, while the good quality of the diamond film produced on this side has been confirmed through Raman spectroscopy.Furthermore, the ZnO films having their c axis perpendicular to the substrate were deposited using reactive magnetron sputtering under the optimal experimental conditions found from XRD measurements. In the SAW device elaboration on this ZnO/bilayer diamond structure, aluminium interdigital transducers (IDTs) were developed by conventional contact UV photolithography on the nucleation side of the freestanding diamond. The frequency response of the device presents harmonics of the acoustic wave modes propagating in the smooth diamond nucleation side. The good agreement obtained between the experimental and theoretical frequency responses attests that the elastic properties of the ZnO and the diamond are similar to those of the single crystal assumed in the theoretical study. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Silicon incorporation in CVD diamond layers
Authors: Barjon J. , Rzepka E. , Jomard F. , Laroche J.‐M. , Ballutaud D. , Kociniewski T. , Chevallier J. 
Published: August 2005

AbstractThe silicon incorporation in diamond is an important issue as silicon is widely used as a substrate for the growth of polycrystalline thin films. Incorporated silicon impurities are suspected to come from the hydrogen etching of the silicon substrate. To clearly establish this point we introduced a solid source of silicon during the growth of a homoepitaxial diamond layer on a HPHT diamond substrate. A quantitative SIMS analysis revealed concentrations of silicon up to 3 × 1019 cm–3 in the diamond layer. Then we propose a scenario for the contamination of polycrystalline diamond grown on silicon substrates: after nucleation, the progressive paving of the silicon surface by 3D grains causes a fast decrease of its incorporation. At coalescence, the silicon substrate is completely covered by a 2D diamond film and the silicon concentration in diamond reaches a residual level. The investigated MPCVD and HFCVD diamond layers grown on silicon substrates present comparable features. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characteristics of excitonic emission in diamond
Authors: Okushi Hideyo , Watanabe Hideyuki , Kanno Shokichi 
Published: August 2005

AbstractDetailed characteristics of excitonic emission in diamond have been studied by theoretical considerations taking into account the indirect semiconductor properties to calculate precise simulated spectra of the excitonic emission. The simulated excitonic emission spectra agree well with the observed spectra in our high quality diamond thin films, showing that the chemical potential of the exciton gas can be reduced precisely. The results indicate that (1) the characteristics of exciton emission of indirect semiconductors are much difference than those of direct ones, (2) exciton collisions cause line broadening and (3) quantum statistical (Bose–Einstein statistics) properties appear for highly excited exciton densities in diamond. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Negative electron affinity on hydrogen terminated diamond
Authors: Takeuchi D. , Ri S.‐G. , Kato H. , Nebel C. E. , Yamasaki S. 
Published: August 2005

AbstractTotal photoyield spectroscopy (TPYS) is applied to characterize the surface electronic properties of p‐ and n‐type chemical‐vapour‐deposited (111) homoepitaxial diamond films with hydrogen terminated (H‐terminated) surfaces. All experiments on H‐terminated high quality diamond show the same threshold energy of 4.4 eV and comparable spectra in the regime 4.4–5.5 eV. A H‐terminated intrinsic IIa (100) sample also show the same result. The onset of electron emission at 4.4 eV on p‐, intrinsic and n‐type diamond indicates that Fermi levels do not affect the sub‐band spectra. Obviously, direct excitation of valence‐band electrons into the vacuum takes place in the close vicinity of the surface. If we assume a transition from valence band maximum the threshold energy of 4.4 eV gives a negative electron affinity (NEA) of –1.07 eV (Eg ∼ 5.47 eV). TPYS therefore allows a precise and direct detection of the NEA of H‐terminated diamond. It is interesting that the expected rise of photoyield as NEA in the regime hv > 5.47 eV is missing in n‐type diamond. We attribute this to a surface space charge region due to ionized phosphorus atoms. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterisation of single crystal CVD diamond particle detectors for hadron physics experiments
Authors: Pomorski M. , Berdermann E. , Ciobanu M. , Martemyianov A. , Moritz P. , Rebisz M. , Marczewska B. 
Published: August 2005

AbstractCharacterisation results from a single‐crystal CVD diamond detector are reported, which is under development for heavy‐ion particle identification and minimum‐ionizing particles timing in nuclear physics experiments. The charge collection efficiency is about 100%, never obtained from polycrystalline CVD‐diamond detectors. An energy resolution of 20 keV (ΔE/E ≈ 0.004) is achieved using a mixed nuclide α‐source, which is comparable to the energy resolution of silicon pin diode detectors. Using low impedance broadband electronics and a ToF technique, where holes or electrons drift separately inside the diamond bulk, the saturation velocity, mobility and lifetime of both charge carriers are estimated. In addition the thermoluminescent properties of the new material are discussed in comparison to polycrystalline diamond. A much lower density of trapping centres has been found for single‐crystal CVD diamond. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of RIE treatments for {111} diamond substrates on the growth of P‐doped diamond thin films
Authors: Tavares Céline , Koizumi Satoshi , Kanda Hisao 
Published: August 2005

AbstractThe reactive ion etching (RIE) procedures were applied for mechanically polished {111} diamond substrates surfaces using oxygen and hydrogen gas sources to improve the crystalline quality of chemical vapor deposited (CVD) n‐type diamond layers. The growth of phosphorus‐doped films was performed on RIE treated diamond substrates by microwave plasma‐assisted CVD using phosphine (PH3) as a doping source. Cathodoluminescence (CL) measurements of the epilayer clearly revealed a significant decrease of the intensity of band‐A emission for samples with RIE pre‐treatment. The Hall mobility was also improved reproducibly for all the RIE pre‐treated samples. It was found that the RIE treatment of diamond {111} substrate is effective to obtain high quality n‐type diamond thin films reproducibly. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Using symbolic computing in building probabilistic models for atoms
Authors: Guiasu Silviu 
Published: August 2005

AbstractThis article shows how symbolic computing and the mathematical formalism induced by maximizing entropy and minimizing the mean deviation from statistical equilibrium may be effectively applied to obtaining probabilistic models for the structure of atoms, using trial wave functions compatible with an average shell picture of the atom. The objective is not only to recover the experimental value of the ground state mean energy of the atom, but rather to better approximate the unknown parameters of these trial functions and to calculate both correlations between electrons and the amount of interdependence among different subsets of electrons of the atoms. The examples and numerical results refer to the hydrogen, helium, lithium, and beryllium atoms. The main computer programs, using the symbolic computing software MATHEMATICA, are also given. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Maltotriose utilization in lager yeast strains: MTT1 encodes a maltotriose transporter
Authors: Dietvorst J. , Londesborough J. , Steensma H. Y. 
Published: August 2005

AbstractMaltotriose is the second most abundant fermentable sugar in wort and, due to incomplete fermentation, residual maltotriose in beer causes both quality and economic problems in the brewing industry. To identify genes that might improve utilization of maltotriose, we developed a library containing genomic DNA from four lager strains and a laboratory Saccharomyces cerevisiae strain and isolated transformants that could grow on YP/2% maltotriose in the presence of 3 mg/l of the respiratory inhibitor antimycin A. In this way we found a gene which shared 74% similarity with MPH2 and MPH3, 62% similarity with AGT1 and 91% similarity with MAL61 and MAL31, all encoding known maltose transporters. Moreover, the gene shared an even higher similarity (98%) with the uncharacterized Saccharomyces pastorianus mty1 gene (M. Salema‐Oom, unpublished; NCBI Accession No. AJ491328). Therefore, we named the gene MTT1 (mty1‐like transporter). We showed that the gene was present in four different lager strains but was absent from the laboratory strain CEN.PK113‐7D. The ORF in the plasmid isolated from the library lacks 66 base pairs from the 3′‐end of MTT1 but instead contains 54 bp of the vector. We named this ORF MTT1alt (NCBI Accession No. DQ010174). 14C‐Maltose and repurified 14C‐maltotriose were used to show that MTT1 and, especially, MTT1alt, encode maltose transporters for which the ratio between activities to maltotriose and maltose is higher than for most known maltose transporters. Introduction of MTT1 or MTT1alt into lager strain A15 raised maltotriose uptake by about 17% or 105%, respectively. Copyright © 2005 John Wiley & Sons, Ltd.
A PMR1‐like calcium ATPase of Aspergillus fumigatus: cloning, identification and functional expression in S. cerevisiae
Authors: Soriani F. M. , Martins V. P. , Magnani T. , Tudella V. G. , Curti C. , Uyemura S. A. 
Published: August 2005

AbstractThe understanding of the controlling factors of calcium homeostasis in Aspergillus fumigatus is very poor, although this ion is involved in several important events of these particular cells. We have cloned, identified and expressed for functional complementation a PMR1‐like Ca2+‐ATPase gene from A. fumigatus. The Afpmr1 gene encodes a protein of 1061 deduced amino acids, containing all the conserved subdomains found in other P‐type ATPases: the phosphatase region, phosphorylation site, FITC labelling site, ATP binding domain; E386, N871, D875 amino acid residues for calcium ion interaction and Q880, a residue that alters ion selectivity in PMR1. The expressed AfPMR1 in S. cerevisiae K616 strain functionally complemented the deficient growth in EGTA (5–20 mM)‐ and MnCl2 (4 mM)‐containing medium. These results demonstrate the first evidence of a Ca2+‐ATPase in A. fumigatus and strongly suggest a role for this enzyme in calcium and manganese homeostasis. Copyright © 2005 John Wiley & Sons, Ltd.
Glucose Intolerance Modifies the Inflammatory Response After Intestinal Ischemia‐Reperfusion
Authors: Garcia‐Perez Juan C. , Arias‐Diaz Javier , Vara Elena , Balibrea Jose L. 
Published: August 2005

AbstractStreptozotocin administration in newborn rats (nSTZ‐rats) leads to adults with mild insulin deficiency and normoglycemia, and is accepted as a model of type 2 diabetes. We examined possible differences in the production of inflammatory mediators between healthy and nSTZ‐rats after ischemia‐reperfusion (I‐R). Two‐month‐old control and nSTZ‐rats were randomly separated into control and intestinal I‐R groups. After reperfusion, samples were obtained from the portal vein (PV) infrahepatic cava vein (ICV), suprahepatic cava vein (SCV), jejunal wall, and pancreas. Nitric oxide (NO), lipid hydroperoxides (LPO), tumor necrosis factor alpha (TNF‐α), 60 kDa receptor (sTNF‐R1), 80 kDa (sTNF‐R2), and intercellular adhesion molecule‐1 (ICAM‐1), were determined. After I‐R, nSTZ‐rats showed increased plasma concentrations of LPO, NO, ICAM‐1 (0.5141 ± 0.083 vs 0.024 ± 0.003, ICV; 0.574 ± 0.075 vs 0.023 ± 0.003, SCV; 0.528 ± 0.067 vs 0.027 ± 0.003 PV; ng/ml), TNF‐α (42.4 ± 5.7 ICV, 248.4 ± 28.2 SCV, and 33.6 ± 4.0 PV. In n STZ‐rats, vs 4.36 ± 0.57, 4.74 ± 0.77, and 3.16 ± 0.32, respectively, in control rats; pg/ml), and sTNF‐R1. Both TNF‐α and NO plasma levels were higher in SCV than in ICV and PV after I‐R. In addition, after I‐R, jejunal wall of nSTZ‐rats showed an increase of TNF‐α IL‐1, and IL‐10 levels. A pre‐existing state of glucose intolerance intensifies the inflammatory response after intestinal I‐R.
Do Germans Keep Patients Too Long in Hospital? A Prospective Randomized Trial
Authors: Dotzenrath Cornelia M. E. , Cupisti Kenko , Raffel Andreas , Aust Birgit , Yang Quh , Krüger Björn , Ohmann Christian , Röher Hans Dietrich , Goretzki Peter E. 
Published: August 2005

AbstractCost‐effectiveness reduces hospital stay for all patients with thyroid surgery but lacks information on medical comparability and patients’ fulfilled expectations. The aim of this study was to assess if a hospital stay of 2 days after thyroid surgery had a negative influence on the medical quality or on health‐related quality of life. In a controlled prospective randomized trial with 238 patients, a postoperative hospital stay of 2 days was compared to one longer than 2 days. The postoperative medical investigation included serum calcium levels, laryngeal nerve function, and suction drainage volume. Health‐related quality of life was assessed on the day of admission before the operation and again 14 days after discharge. Fourteen days after discharge patients were also asked about their subjective health. Despite the study design, it was necessary, for ethical reasons, to let the patients decide when to leave the hospital. In the 2‐day study group, 56.6% of the patients preferred hospitalization for more than 2 days (most choosing 3 days). Medical reasons were hyperthyroidism (p < 0.02) and postoperative hypocalcemia (p < 0.03). In the control group 28% left the hospital after 2 days. Only 35% of the patients left the hospital at the second postoperative day, but 60% of these patient supported this shorter hospitalization. Health‐related quality of life and self‐rated health was significantly higher in patients leaving the hospital on the second postoperative day. A 2‐day hospital stay after thyroid surgery is possible and does not show medical or health‐related quality of life disadvantages in patients with an uncomplicated postoperative course who consider themselves healthy.