bluuebunny/crossref_metadata_2025_split huggingface dataset:
Irradiation effects on electrical properties of cellulose nitrate
Authors: Amin M. , Darwish K. A. , Mounir M. , Elez M. Abu 
Published: April 2003

AbstractCellulose nitrate (CA‐80‐15) films were exposed to UV and neutron irradiations. An increase of the electrical conductivity was observed. The values of the activation energy diminish with irradiation from 0.42 to 0.15 eV for UV and to 0.31 eV for neutron irradiation. A sharp increase in the current was observed after exposing CA‐80‐15 samples to fission neutron fluences of 1*107 n/cm2. The electrical conduction in cellulose nitrate is governed by the Shottky mechanism. The value of the electron affinity of the polymer used is 4.46 eV. This value is increased after both types of irradiation. The dielectric permittivity (ε′) of the above samples together with the dielectric loss factor (ε″) were measured over a range of temperatures (293–403 K) at fixed frequencies (1*103, 1*104, and 1*105Hz). Three neutron exposures (ϕ = 1*105, 1*106, and 1*107 n/cm2) were used. The obtained results made it possible to determine a complete set of conduction parameters including dielectric susceptibility χ, ac conductivity αac, and temperature coefficient of permittivity TC. © 1995 John Wiley & Sons, Inc.
Propene polymerization with MgCl2‐supported TiCl4/dioctylphthalate catalyst. II. Effects of polymerization conditions on the microstructure of isotactic polymer
Authors: Yang Chun B. , Hsu Cheng C. 
Published: April 2003

AbstractPropene was polymerized over the MgCl2‐supported TiCl4/dioctylphthalate catalyst in heptane. Polymer products obtained under different polymerization conditions were separated into isotactic and atactic polypropenes by the extraction of boiling n‐heptane. The effects of polymerization time, cocatalyst type, cocatalyst/catalyst ratio, polymerization temperature, and external base/cocatalyst ratio on the isotactic triad of the isotactic portion of polypropene were investigated 2,2,6,6‐Tetramethyl piperidine (TMPIP), dimethoxy diphenyl silane (DMDPS), and t‐butylmethyl ether (TBME) were employed as the external Lewis base. High concentrations of the first two bases caused a decrease in isotactic triads in the isotactic polymer, while TBME showed no significant effects. The difference can be attributed to the different roles these external bases play in polymerization. © 1995 John Wiley & Sons, Inc.
Gas separation properties of isophorone‐based polyarylates
Authors: Jager Jan , Hendriks Anton J. J. 
Published: April 2003

AbstractThe oxygen and nitrogen permeability coefficients and oxygen/nitrogen selectivities of a series of isophorone‐based polyarylates have been measured. The monomeric bisphenols used in this study are easily accessible in two steps from cheap, commercially available, isophorone (3,5,5‐trimethyl‐2‐cyclohexen‐1‐one). The corresponding polyarylates can easily be prepared in high yield by means of the well‐known interfacial polycondensation route. The effect of substituents (CH3, Cl, or Br) on all positions ortho to both hydroxyl groups in the bisphenol and the influence of the terephthalic acid/isophthalic acid molar ratio in the polyarylate on the oxygen/nitrogen separation performance have been studied in detail. It has been found that the polyarylate with four bromine substituents displays a significantly increased oxygen and nitrogen permeability coefficient, combined with a high oxygen/nitrogen selectivity, relative to conventional polyarylates. Obviously, the bulky 3,3,5‐trimethylcyclohexylidene moiety in the bisphenol has structural features that hinder an effcient chain packing and reduce polymer segmental mobility. A further improvement in the gas permeability of these polyarylates can be achieved when the bulky t‐butyl group is introduced on the 5 position in isophthalic acid. For example, the polyarylate prepared from the isophorone‐based bisphenol with four methyl substituents and 5‐t‐butylisophthalic acid is characterized by an oxygen permeability coefficient of 34.7 Barrer! © 1995 John Wiley & Sons, Inc.
Graft copolymerization of acrylamide on cotton cellulose in a limited aqueous system following pretreatment technique
Authors: Ghosh P. , Dev D. , Samanta A. K. 
Published: April 2003

AbstractGraft copolymerization of acrylamide on cotton (dialdelyde cellulose, DAC) fibers and fabrics was studied in a limited aqueous system using K2S2O8 as the initiator. Grafting parameters under different sets of conditions were determined and the mechanism of graft copolymerization discussed. Optimum conditions for grafting were established and the effect of polyacrylamide grafting on tenacity, modulus, breaking elongation, and stiffness of the cotton (DAC) fabrics and on their dyeability and moisture regain properties were also studied; 9–10% grafting of polyacrylamide on (DAC) fabric at pH 7–10 imparts an improved balance in its mechanical and other properties. © 1995 John Wiley & Sons, Inc.
Semianalytical solution of irreversible anionic polymerization with unequal reactivity in batch reactors
Authors: Sailaja R. R. N. , Kumar Anil 
Published: April 2003

AbstractAnionic polymerization with unequal reactivity in batch reactors is a nonlinear problem, and in order to determine the rate constants using the experimental molecular weight distribution (MWD) and conversion vs. time of polymerization, the simulation equations need to be solved repeatedly. In this work, we evolved an efficient algorithm in which the experimental MWD yields the reactivity ratio directly while conversion data give the values of all rate constants. For doing this, we proposed a series solution for the reacting species in terms of monomer conversion. A technique similar to the finite element method for boundary problems is used to divide the conversion into subdomains. The size of these steps is decided by a convergence criterion and results were determined at the end of the conversion domain through sequential computation. The scheme can be implemented on a personal computer and is considerably faster and more efficient. We used experimental data from the literature and demonstrated our technique of evaluating the rate constants. © 1995 John Wiley & Sons, Inc.
Time‐dependent permeation of carbon dioxide through a polyimide membrane above the plasticization pressure
Authors: Wessling M. , Huisman I. , Boomgaard Th. v. d. , Smolders C. A. 
Published: April 2003

AbstractThe time‐dependent permeation behavior of a glassy polyimide is studied above and below the plasticization pressure with carbon dioxide as the permeating gas. The work particularly focuses on the quantification of the slow increase in permeability at feed pressures above the plasticization pressure. Significant differences in permeation behavior were found for membranes with and without permeation history. Introducing the quantity “conditioning time” allows one to compare the results obtained for membranes with different permeation history. The concept of conditioning time furthermore allows one to quantify the aging of a membrane plasticized during previous permeation. © 1995 John Wiley & Sons, Inc.
Structural and thermal behavior of PC/PBT blends
Authors: Mishra S. P. , Venkidusamy P. 
Published: April 2003

AbstractBlends of polycarbonate (PC) with poly(butylene terphthalate) (PBT) were characterized using density measurements, DSC, IR, and TGA. Addition of PBT increases the density values of blends linearly. All the blends show a single glass transition temperature, indicating the miscibility of the two polymers in the amorphous phase. With more than 6% addition of PBT to PC, PBT crystallizes as per its own crystal structure. The addition of 4% PBT to PC improves the thermal stability at higher temperature than does pure PC. IR studies shows that addition of PBT improves the intermolecular forces in PC, in particular, on the endgroup and the CCH3 and CO groups as indicated in the frequencies 1020, 1370, and 1770–1790 cm−1. © 1995 John Wiley & Sons, Inc.
Expression of the type III TGFβ receptor during chick organogenesis
Authors: Olivey Harold E. , Barnett Joey V. , Ridley Bettye D. 
Published: April 2003

AbstractTransforming growth factor β (TGFβ) is a regulator of embryonic development. The role of specific TGFβ receptors is emerging, and a unique role for the type III TGFβ receptor (TBRIII) has been suggested. We report the pattern of TBRIII expression in chicken embryos from 2 to 14 days in ovo. Anat Rec Part A 272A:383–387, 2003. © 2003 Wiley‐Liss, Inc.
Optimization of information searching efficiency in Web space by using probability of target location
Authors: Naito Seiichiro , Kobayashi Aki , Yamaoka Katsunori , Sakai Yoshinori 
Published: April 2003

AbstractWith the spreading use of the Web, there are increasing opportunities for information retrieval from the Internet. It is thus desirable to establish a method that can efficiently locate information required by a user from Web space, over which diverse information is scattered. This paper discusses a search scheme through links in Web space where the target search efficiency is maximized by utilizing the knowledge owned by the links. First, assuming that the probability that the target is present can be estimated from knowledge in Web pages, the estimation procedure is discussed. Then, the search process used to trace the links in Web space is modeled by a tree structure. Two problems are defined, namely, minimization of the retrieval cost and maximization of the number of retrieved pages. For each of these, an efficient search procedure is proposed. Lastly, the performance of the method is analyzed. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(10): 45–54, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10048
A Kalman filter using texture for noise reduction in SAR images
Authors: Tsuchida Masayoshi , Haseyama Miki , Kitajima Hideo 
Published: April 2003

AbstractIn this paper, we propose a noise reduction method for synthetic aperture radar (SAR) images that uses a Kalman filter. The noise in SAR images is primarily generated by speckle and appears as salt‐and‐pepper noise. Speckle noise is known to have the multiplicative statistical property, but this property may not hold depending on the region. Consequently, adequate noise removal is difficult. In radar, the expected values of the backscattered waves change due to the type of reflecting object. The proposed method segments an image into several regions based on the texture and varies the parameters in Kalman filtering in response to the region. By varying the parameters, the processing can account for the noise generated primarily by speckle in actual SAR images and the changes in the statistical properties of the backscattered waves. In this paper, we apply the proposed method to synthetic test images and to actual SAR images to quantitatively evaluate the noise reduction and present the results. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(10): 21–32, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10065
Strain‐specific mammary proliferative lesion development following lifetime oral administration of ochratoxin A in DA and Lewis rats
Authors: Son Woo‐Chan , Kamino Kenji , Lee Yong‐Soon , Kang Kyung‐Sun 
Published: April 2003

AbstractOTA, a potent nephrotoxin in several species, is a renal carcinogen in animals and is implicated in the etiology of BEN. The NTP classified OTA as having clear evidence of carcinogenic activity, based on uncommon tubular adenomas and tubular cell carcinomas of the kidney and multiple fibroadenomas of the mammary gland, seen in the rat. As shown previously (Castegnaro et al., Int J Cancer 1998;77:70–5), induction of renal tumors by OTA is sex‐ and strain‐specific in DA and Lewis rats, with DA males being most responsive and DA females being resistant; however, that report was confined to the kidney and urinary tract. To obtain OTA‐induced tumorigenic information in rats, we administered OTA (0.4 mg/kg) by oral gavage to both DA and Lewis rats for their lifetimes and extended the investigation to complete histopathology of all tissues and organs. We also observed the characteristic renal tumor that is highly strain‐ and sex‐specific, and there were increased incidences of proliferative mammary lesions in Lewis rats but not in DA rats, indicating that these were also strain‐specific. In view of the NTP report of OTA treatment‐related mammary fibroadenoma in F344 rats, we observed increased mammary proliferative lesions in Lewis rats but not in DA rats. Our results suggest that OTA may play some role in mammary tumor development in some rat strains. © 2003 Wiley‐Liss, Inc.
Intake of fruits, vegetables and selected micronutrients in relation to the risk of breast cancer
Authors: Malin Alecia S. , Qi Dai , Shu Xiao‐Ou , Gao Yu‐Tang , Friedmann Janet M. , Jin Fan , Zheng Wei 
Published: April 2003

AbstractHigh fruit and vegetable intake has been linked with a reduced risk of breast cancer, but evidence is not consistent. We investigated the associations of breast cancer risk with vegetables, fruits and related micronutrient intake in a population‐based case–control study among Chinese women in Shanghai, where dietary patterns differ substantially from other study populations. Included in the study were 1,459 incident breast cancer cases and 1,556 frequency‐matched controls. Usual dietary habits were assessed by in‐person interviews. Logistic regression was used to compute adjusted odds ratios (ORs) and 95% confidence intervals (CIs) to measure strength of the associations. There was no association between breast cancer risk and total vegetable intake. The risk of breast cancer declined, however, with increasing intake of dark yellow‐orange vegetables (trend test, p = 0.02), Chinese white turnips (trend test, p ≤ 0.001), and certain dark green vegetables (trend test, p ≤ 0.001) with adjusted OR in the highest quintile being 0.79 (95% CI = 0.60–0.98), 0.67 (95% CI = 0.53–0.85) and 0.65 (95% CI = 0.51–0.83) respectively. Intake of fruits, except watermelons and apples, was inversely associated with breast cancer risk (p‐values for trend tests ≤0.05). Our study suggests that high intake of certain vegetables and fruits may be associated with a reduced risk of breast cancer. © 2003 Wiley‐Liss, Inc.
Kinetics of substitution of aqua ligands from cis‐diaqua (ethylenediamine)platinum(II) perchlorate by L‐asparagine in aqueous medium
Authors: Bera Sujit K. , Chandra Swapan K. , De Gauri S. 
Published: April 2003

AbstractThe kinetics of the interaction of L‐asparagine with [Pt(ethylenediamine)(H2O)2]2+ have been studied spectrophotometrically as a function of [Pt(ethylenediamine)(H2O)22+], [L‐asparagine], and temperature at pH 4.0, where the substrate complex exists predominantly as the diaqua species and L‐asparagine as the zwitterion. The substitution reaction shows two consecutive steps: the first step is the ligand‐assisted anation and the second one is the chelation step. Activation parameters for both the steps have been calculated using Eyring equation. The low ΔH1≠ (43.59 ± 0.96 kJ mol−1) and large negative values of ΔS1≠ (−116.98 ± 2.9 J K−1 mol−1) as well as ΔH2≠ (33.78 ± 0.51 kJ mol−1) and ΔS2≠ (−221.43 ± 1.57 J K−1 mol−1) indicate an associative mode of activation for both the aqua ligand substitution processes. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 252–259, 2003
Versuche zur darstellung von polymeren kieselsäureestern
Authors: Staudinger von Hermann , Hahn Walter 
Published: April 2003

AbstractEs wurden Versuche zur Herstellung von linearen Polymeren aus Dialkoxy‐ bzw. Diaryloxy‐dichlorsilanen und zweiwertigen Alkoholen ausgeführt. Je nach Art des verwendeten Alkohols bilden sich ‐ in einigen Fällen nebeneinander ‐ cyclische monomere oder polymere Verbindungen, die jedoch nicht sehr hochmolekular sind.Die aus Diphenoxy‐dichlorsilan erhaltenen Ester verseifen schon an feuchter Luft leicht. Beständiger sind die durch Kondensation von Dicyclohexoxy‐dichlorsilan mit Diolen erhaltenen Produkte. Hier ist vor allem der Terpinester gegen Wasser relativ gut beständig.
Über die bildung von spirocyclischen kieselsäureestern aus siliciumtetrachlorid und zweiwertigen alkoholen
Authors: Hahn von Walter 
Published: April 2003

AbstractDurch Umsetzung von verschiedenen zweiwertigen Alkoholen mit Siliciumtetrachlorid wurden spirocyclische Ester der Orthokieselsäure mit 5 er‐, 6 er‐, 7 er‐ und 8 er‐ Ringen erhalten. Die Reaktion erfolgt mit 1,2‐ditertiären Glykolen sehr leicht; bei 1,3‐, 1,4‐ und 1,5‐Diolen wird in stark verdünnter Lösung gearbeitet. Mit Glykol selbst und höheren als 1,5‐Diolen wurden vernetzte Produkte erhalten.
Über die pharmakologie wasserlöslicher polysaccharide und ihrer derivate in abhängigkeit von molekülgröße, molekülgestalt und art der substituenten
Authors: Husemann von E. , Lötterle R. , Wiedersheim M. , Hertlein W. 
Published: April 2003

AbstractEs wurde die Wirkung wasserlöslicher Polysaccharide und ihrer Derivate auf das weiße Blutbild, die Körpertemperatur und die Blutsenkungsgeschwindigkeit von Kaninchen untersucht, um Zusammenhänge zwischen Molekülgröße, Molekülgestalt und elektrochemischen Eigenschaften aufzufinden. Dabei wurden folgende Ergebnisse erhalten:

Homöopolare unverzweigte Substanzen rufen eine Leukopenie hervor und steigern die Körpertemperatur. Bei erhöhter Kettenlänge nimmt die Dauer der Leukopenie und die Höhe des Fiebers zu. Die Blutsenkungsgeschwindigkeit wird oberhalb eines Polymerisationsgrades von 200 beschleunigt, unterhalb dieses Wertes gehemmt.
Homöopolare verzweigte Substanzen haben keinen Einfluß auf Blutbild und Körpertemperatur. Auf die Blutsenkungsgeschwindigkeit wirken sie entsprechend der Länge der Moleküle unabhängig vom Molekulargewicht.

Carboxylhaltige unverzweigte Substanzen beeinflussen weder Blutbild noch Körpertemperatur, noch Blutsenkungsgeschwindigkeit.
Unverzweigte Polysaccharidschwefelsäureester bewirken unabhängig vom Molekulargewicht eine Leukocytose. Die Körpertemperatur wird nicht beeinflußt. Die Blutsenkungsgeschwindigkeit wird verlangsamt.
Viscosities of dilute solutions of rubber and chlorinated rubbers
Authors: Kapadia Faridum H. 
Published: April 2003

AbstractViscosity studies of solutions in carbon tetrachloride of sol, gel, whole rubber and chlorinated rubber, show an anomalous increase in viscosity at high dilutions. In certain cases, this increase is followed by a decrease in ηsp/c, giving intercepts at much lower values than ordinarily obtained by extrapolation in viscosity studies.
Über Lösungen von Cellulose in Tetraäthylammoniumhydroxyd
Authors: Krässig Von H. , Siefert E. 
Published: April 2003

AbstractDurch einen Vergleich der Viskositätszahlen verschieden hochmolekularer Cellulosen in Kupferhydroxydammoniak und in Tetraäthylammoniumhydroxyd‐Wasserlösungen wird gezeigt, daß der Lösungszustand in beiden Lösungsmitteln der gleiche ist.Für die Beziehung der Molekülgröße und der Viskosität von Cellulose in Tetraäthylammoniumhydroxyd‐Wasser gilt in gleicher Weise wie für die Lösungen in Kupferhydroxyd‐Ammoniak das Staudinger sche Viskositätsgesetz. Die Km‐Konstante des Tetraäthylammoniumhydroxyd‐Wassers als Lösungsmittel wurde zu etwa 5,8·10−4 bestimmt.Die Lösungen sind sehr stabil gegenüber Sauerstoff und Luft. Man kann aus ihnen Cellulose ohne Schutzmaßnahmen für Sauerstoffausschluß umfällen.Cellulosen höheren Polymerisationsgrades als etwa 1500 lösen sich in Tetraäthylammoniumhydroxyd‐Wasser nicht mehr vollständig.
Interdiffusion between rubber and solvents under static conditions
Authors: Pande J. B. , Ramakrishnan C. S. , Raghunath D. , Kapur S. L. 
Published: April 2003

AbstractExperimental evidence is presented to show that the dissolution of rubber in a solvent is a diffusion process in which both components interdiffuse into one another. The influence of light in such process has been demonstrated. Replacement of air by nitrogen in the process of diffusion has also been studied.
Polymere acroleine, I. Mitt. Untersuchungen über die polymerisation des acroleins.
Authors: Schulz Von Rolf C. 
Published: April 2003

AbstractUnter der Einwirkung typischer Polymerisations‐Katalysatoren wie z. B. Azoisobuttersäurenitril, Peroxyde, Redox‐Systeme, metallorganische Verbindungen und Friedel‐Crafts‐Katalysatoren geht Acrolein in polymere Produkte über. Deren physikalische Eigenschaften (thermische Beständigkeit, Viskosität der Lösungen u. a.) hängen von den Polymerisationsbedingungen ab. Einige der erhaltenen polymeren Produkte unterscheiden sich deutlich von den bisher bekannten Polyacroleinen.
Über umsetzungsprodukte von aliphatischen diaminen mit formaldehyd. 430. Mitteilung über makromolekulare verbindungen
Authors: Krässig Von Hans 
Published: April 2003

AbstractBei der Reaktion von N,N′‐Disubstitutionsprodukten oder Monochlorhydraten aliphatischer Diamine mit Formaldehyd in Molverhältnis 1 : 1, entstehen bei äthylen‐ bzw. Propylendiamin Derivate des Tetrahydroimidazols bzw. des Hexahydropyrimidins oder diese Heterocyclen resp. deren tautomere, offene Form selbst. Die höheren Homologen reagieren unter Bildung von entsprechend substituierten Methylendiaminen niedrigen Molekulargewichtes oder von Monomethylen‐diaminen, von denen sich 3 Moleküle unter Bildung des entsprechenden Hexahydrotriazins absättigen.Den Reaktionsprodukten der aliphatischen Diamine mit 4 und mehr C‐Atomen mit Formaldehyd im Molverhältnis 1 : 2 ist die Struktur vernetzter, Hexahydrotriazinringe enthaltender Poly‐bismethylendiamine zuzuerkennen. Wie die Poly‐oxymethylene ein Modell für lineare Kettenpolymere darstellen, könen diese Produkte als Modell für vernetzte Makropolymere angesehen werden.An den syrupösen Umsetzungsprodukten des Tetramethylendiamins wurde durch Fraktionierungen, Untersuchungen der Temperaturabhängigkeit des überganges in die amorphen, unlöslichen Körper, Endgruppenbestimmungen mit Diphenylketen sowie partielle katalytische Hydrierung und durch Viskositätsmessungen Einblick in die Struktur gewonnen. Die Tatsache, daß auch die niedrigsmolekularen Anteile keine Methylolgruppen enthalten, sprechen für einen Bildungsmechanismus durch Polymerisation. Der festgestellte hohe Absättigungsgrad wird mit dem Vorliegen von Hexahydrotriazinkonfigurationen erklärt.Die kristallinen Umsetzungsprodukte von äthylendiamin und Propylendiamin mit Formaldehyd in Molverhältnis 1 : 2 sind cycl.‐Bismethylen‐di‐tetrahydroimidazol resp. cycl.‐Tetramethylen‐tetra‐hexahydropyrimidin. Von ersterem existieren Isomere. Eines konnte rein isoliert werden. Bei dem unter partieller Aufspaltung verlaufenden Umsatz mit schwefliger Säure wurden in beiden Fällen N‐Methansulfosäuren der in den Molekülen enthaltenen Heterocyclen isoliert und so der Strukturbeweis geführt.
The mechanism of the radiation‐induced crosslinking of polyolefins
Authors: Geymer D. O. 
Published: April 2003

AbstractPolypropylene, as a model for polyolefins, was irradiated with 60Co‐γ‐radiation in the presence of various radical scavengers and ion scavengers to determine whether the crosslinking reaction is free radical or ionic in nature. it was found that iodine and compounds having labile hydrogen atoms can inhibit the radiation‐induced crosslinking. The nature and relative effectiveness of the inhibitors show, that the crosslinking reaction is a rather slow and thermal free radical reaction. The rate of crosslinking of irradiated polypropylene depends upon the temperature, and at ‐196°C. it is so slow as to be undetectable.