bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nuclear spin relaxation study of aqueous raffinose solution in the presence of a gadolinium contrast agent
Authors: Ghalebani Leila , Kruk Danuta , Kowalewski Jozef 
Published: December 2004

AbstractParamagnetic enhancement of nuclear spin–lattice relaxation rates (PREs) was measured in aqueous solution of the trisaccharide raffinose in the presence of a gadolinium(III) complex, GdDTPA–BMA, used as a magnetic resonance imaging contrast agent. The relaxation enhancement of aqueous protons was measured over a broad range of magnetic fields, using field‐cycling apparatus in addition to conventional spectrometers. The nuclear magnetic relaxation dispersion profile thus obtained was interpreted with a recently developed model, allowing for both inner‐ and outer‐sphere relaxation. The relaxation enhancement for the carbon‐13 nuclei in raffinose was studied under high‐resolution conditions at three magnetic fields, whereas the sugar proton PRE was measured at two fields. The PRE of the sugar nuclei could be interpreted in a consistent way, assuming that it was caused by the outer‐sphere mechanism. The electron spin relaxation was found to be a less important source of modulation of the electron–nuclear dipole–dipole interaction than the mutual translational diffusion. Copyright © 2004 John Wiley & Sons, Ltd.
Ring current effects on nuclear magnetic shielding of carbon in the benzene molecule
Authors: Ferraro M. B. , Faglioni F. , Ligabue A. , Pelloni S. , Lazzeretti P. 
Published: December 2004

AbstractThe differential Biot–Savart law of classical electrodynamics was applied to develop a ring current model for the magnetic shielding of the carbon nucleus in benzene. It is shown that the local effect of the π currents, induced by a magnetic field normal to the molecular plane, on the $\sigma_{\|}^{\rm C}$ out‐of‐plane shielding tensor component vanishes. However, approximately 10% of $\sigma_{\|}^{\rm C}$ is due to the shielding contributions from π current density in the region of the other carbon atoms. Magnetic shielding density maps obtained via quantum mechanical procedures confirm the predictions of the classical model. Copyright © 2004 John Wiley & Sons, Ltd.
Antioxidant status decreases in children with acute lymphoblastic leukemia during the first six months of chemotherapy treatment
Authors: Kennedy Deborah D. , Ladas Elena J. , Rheingold Susan R. , Blumberg Jeffrey , Kelly Kara M. 
Published: December 2004

AbstractBackgroundChildren undergoing treatment for acute lymphoblastic leukemia (ALL) receive combination chemotherapy and many of the components are associated with free radical production.ProcedureAmong 103 children newly diagnosed with ALL, plasma concentrations of antioxidants, total antioxidant capacity (ORAC), and DNA oxidized base 8‐oxodeoxyguanosine (8‐oxo‐dG) were analyzed at baseline and 3 and 6 months after diagnosis.ResultsPlasma vitamin A, antioxidants, 8‐oxo‐dG, and ORAC changed from diagnosis through the first 6 months of ALL therapy. In patients with higher plasma concentrations of vitamin A, E, total carotenoids, ORAC, and 8‐oxo‐dG there was a beneficial association with fewer dose reductions, fewer infections, improved quality of life, less delay in chemotherapy treatment schedule, reduced toxicity, and fewer days spent in the hospital. There were also adverse relationships demonstrated.ConclusionsAmong children with ALL, antioxidant levels and oxidative stress appear to be associated with duration and complications of treatment. © 2004 Wiley‐Liss, Inc.
Thermophysical properties of anhydride‐cured epoxy/nano‐clay composites
Authors: Miyagawa Hiroaki , Rich Michael J. , Drzal Lawrence T. 
Published: December 2004

AbstractPolymer nano‐composites made with a matrix of anhydride‐cured diglycidyl ether of bisphenol A (DGEBA) and reinforced with organo‐montmorillonite clay were investigated. A sonication technique was used to process the epoxy/clay nano‐composites. The thermal properties of the nano‐composites were measured with dynamic mechanical analysis (DMA). The glass transition temperature Tg of the anhydride‐cured epoxy was higher than the room temperature (RT). For samples with 6.25 wt% (4.0 vol%) of clay, the storage modulus at 30°C and at (Tg + 15)°C was observed to increase 43% and 230%, respectively, relative to the value of unfilled epoxy. The clay reinforcing effect was evaluated using the Tandon‐Weng model for randomly oriented particulate filled composites. Transmission electron microscopy (TEM) examination of the nano‐composites prepared by sonication of clays in acetone showed well‐dispersed platelets in the nano‐composites. The clay nano‐platelets were observed to be well‐intercalated/expanded in the anhydride‐cured epoxy resin system. POLYM. COMPOS., 26:42–51, 2005. © 2004 Society of Plastics Engineers.
Changes in prescribing of inhaled corticosteroids (1999–2002) in Scotland
Authors: Boyter Anne C. , Steinke Douglas T. 
Published: December 2004

AbstractPurposeTo investigate the trend in prescribing of inhaled corticosteroids and general practitioner (GP) consultations for respiratory diseases.MethodsA longitudinal observation study of all prescriptions, from primary care, for inhaled corticosteroids dispensed in Scotland from January 1999 to May 2002 was undertaken.The main outcome measures were the trends in prescribing of inhaled corticosteroids and GP consultations for respiratory diseases.Results and conclusionsThe prescribing of all inhaled corticosteroids has risen over the study period. The rise in prescribing of the combination product containing fluticasone and salmeterol appears not to have been at the expense of the prescribing of fluticasone alone while the prescribing of the budesonide/eformoterol combination may be at the expense of budesonide (BUD) alone. GP consultations for both asthma and chronic obstructive pulmonary disease (COPD) have declined over a similar period.The increased prescribing of inhaled corticosteroids over this period is associated with the increased use of the fluticasone/salmeterol combination rather than an increase in the use of all inhaled corticosteroids. The accompanying fall in number of consultations with GPs may be due to this increased prescribing or a move to nurse led clinics. Copyright © 2004 John Wiley & Sons, Ltd.
Thermomechanical studies of amorphous and crystalline polymers
Authors: Sidorovich A. V. , Kushinsky E. V. 
Published: December 2004

AbstractTranslated from: Vysokomolekuliarnye Soedineniia 2, 778–84 (May 1960). A thermomechanical study was made of the softening of crystalline polymers during uniform, uniaxial stretch and also of the effect of the rate of heating upon the softening or amorphous polymers. The effect of the tensile force on the thermo‐mechanical behavior of various polymers was measured over the range 20 to 100 kg/cm2 and within wide temperature limits (−150° to 250°C). Ribbons 50 mm long, 2‐4 mm wide and 0.05 to 0.5 mm thick served as specimens.
Ultraviolet degradation of plastics and the use of protective ultraviolet absorbers
Authors: Hirt R. C. , Searle N. Z. , Schmitt R. G. 
Published: December 2004

AbstractThe degradation of plastics by ultraviolet energy and the use of protective ultraviolet absorbers to improve stability necessitate studies along several lines. These include (a) the measurement of the ultraviolet spectral energy distribution of sunlight and of the indoor accelerated test sources, (b) the measurement of the extent of degradation as a function of the wavelength of the incident radiation, (c) an estimate of the absorbing effectiveness of the added protective agents, and (d) the stability of the protective ultraviolet absorbers themselves.
The effect of extrusion variables on the fundamental properties of tubular polythene film
Authors: Huck N. D. , Clegg P. L. 
Published: December 2004

AbstractThe mechanism of formation of tubular polythene film is a complicated process, and extensive studies have shown that the properties of the film made are influenced profoundly and in a complex way both by the processing conditions used by certain design features of the equipment. Studies of the effect of the extrusion variables on the more important film properties, both optical and mechanical, are reviewed in this paper. The results are discussed in terms of the fundamental nature of polythene film, its surface, its crystalline structure and its orientation.
Inorganic‐organic high polymers, phenoxyaldehyde resins of Titanium (IV) and Hafnium (IV)
Authors: Landry R. J. , Bartel E. H. 
Published: December 2004

AbstractA new series of inorganic‐organic high polymers have been synthesized namely; the metaloxene polymers of phenolaldehyde. Titanium (IV), Zirconium (IV) and Hafnium (IV) phenolaldehyde have been prepared and other metals especially the refractory type metals may merit further development as calorobic plastic materials. The hafnium resin has been compression molded into a rocket‐nozzle insert shape with satisfactory rocket‐firing results.
The thermodynamics of biaxial elongation
Authors: Stein Richard S. 
Published: December 2004

AbstractIf temperature variations of forces in both directions are observed simultaneously at constant simple dimensions, internal energy and entropy changes on elongation in those directions may be calculated at constant volume and in the more common experimental condition of constant pressure. Thermodynamic derivatives at constant volume are important for fundamental molecular interpretation being related to configuration change. Constant pressure quantities were therefore changed into constant volume ones by the use of an evaluated correction term, involving average Young Moduli and thermal expansion coefficient.
Polymers as conductors and semi‐conductors
Authors: Atlas S. M. , Becher M. , Mark H. F. 
Published: December 2004

AbstractMobile ions can be introduced thereby increasing the conductivity, with a limiting operating temperature range of 200°–250°C. Conductivity can be increased with the formation of conjugatd double bonds. Polymeric compounds may be synthesized with metallocyclic groups, where an atom of metal is bound to nitrogen atoms in a heterocyclic system in the basic chain of conjugation of the macromolecule. Here phtalocyanimes possess the greatest thermal stability. Lastly there are semiconducting polymers with conjugated double bonds containing hetero‐atoms in the principle chain, having unpaired electrons of oxygen and nitrogen.
Physical techniques used in studying interfacial phenomena
Authors: Patrick Robert L. 
Published: December 2004

AbstractAdsorption studies on powdered and planar surfaces yield significant information regarding the rate and degree of interaction between the substrate and the organic adsorbate. Investigative tools include contact angle measurement, radiotracer methods, ellipsometry, x‐ray diffraction, electron diffraction, elegant infrared techniques, dynamic desorption techniques, and film balance applications.
The effect of polymerization catalysts on the rate of degradation of isotactic polypropylene
Authors: Ryshavy D. , Balaban L. 
Published: December 2004

AbstractOne of the reasons for purification of low‐pressure polymerization products is the assumed degradation effects of retained catalysts. Degree of degradation was determined from the change in viscosity number. Effects of catalysts on active sights and deactivation were noted along with degradation in the presence of air and oxygen in addition to determining, the effect of antioxidants. Individual components of the catalyst may have the ability to intensify the effect of any antioxidant and affect the rate of degradation where catalyst influence was better defined in the presence of oxygen.
Bibliography on ultraviolet degradation and stabilization of plastics
Authors: Searle N. Z. , Hirt R. C. 
Published: December 2004

AbstractA bibliography of references from 1957 through 1960 was prepared containing the following sub‐headings: Protective Ultraviolet Absorbers, Light Sources, Light Fastness Evaluation, Plastics Degradation and Stabilization Polyesters, Polystyrene, Polyvinylchloride, Polyethylene, Polyacrylo and Methacrylonitrile, Polymethyl Methacrylate, Cellulose Acetate and Nitrate, Polyvinyl alcohol, Polyamides, Wool, Rubber, Silicone Resin, Wood, Dyes and Paint Films, Epoxy, Melamine and Urea Formaldehyde, Oil Films, General Mechanical Degradation, Free Radicals and ESR, Photochemistry, Photochemistry and Spectroscopy at Low Temperatures, Antioxidants and Free Radical Scavengers, Flash Photolysis, Energy Transfer, Phosphorence and the Triplet State, Fluorescence.
Dynamic elastic behavior or high polymers at audiofrequencies
Authors: Sauer J. A. 
Published: December 2004

AbstractA brief description is given of the use of a resonant‐bar type apparatus for measurement of the dynamic elastic modulus and the associated damping or internal friction of a solid polymer. Each different type of polymer is found to exhibit a characteristic internal friction spectrum when explored over the temperature range from liquid nitrogen temperatures to the melting point. These spectra are characterized by the occurrence of one or more peaks in the mechanical loss data centered about certain temperatures, accompanied by an associated drop in dynamic modulus. By variation of polymer composition and of polymer structure, by addition of low molecular weight compounds, and by subjection of samples to irradiation, considerable additional information can be gained that would be helpful in determining the nature of the molecular mechanisms that are responsible for the observed transitions. Dynamic mechanical data are presented and discussed for a series of poly(alpha olefins) with methyl, ethyl, propyl, isopropyl and isobutyl side chains to depict the effects of crystallinity, side chain length and side chain structure on the observed transitions.
Dynamic shear behavior of high polymers at low frequencies
Authors: Sinnott K. M. 
Published: December 2004

AbstractThe experimental techniques used to measure the dynamic shear behaviour of polymers at low frequencies, that is below 10 sec−1, are discussed with particular reference to the torsion pendulum. The various types of relaxations which can occur in amorphous and semicrystalline polymers are considered. Polymethyl methacrylate, polyethyl methacrylate, and polystyrene are examples of amorphous polymers. The effects of crosslinking, intermolecular forces, steric effects, and plasticizers on the main glass transition of other amorphous polymers are also described. Polytetrafluorethylene is an example of a linear, semi‐crystalline polymer. The effect of introducing trifluoromethyl groups along the chain in copolymers of tetrafluoroethylene and hexafluoropropylene is described. Results obtained with polypropylene are also discussed.
Creep of high polymers
Authors: Williams Malcolm L. , Howard William H. 
Published: December 2004

AbstractFor polymers the isothermal creep compliance shows a major dispersion region from the glassy compliance Jg to the quasi‐equilibrium compliance Je. Further increases in compliance are associated with viscous flow. There is no detailed molecular mechanism to explain these phenomena although the modified Rouse theory and the postulated entanglement coupling present a reasonable physical concept. To empirically describe the creep curves of polycrystalline metals, a power law (\documentclass{article}\pagestyle{empty}\begin{document}$ \dot \varepsilon $\end{document} = mt−n) has frequently been used, where \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \varepsilon $\end{document} is the creep rate, t is the time and m and n are constants with O⩽n⩽. In particular, n equal to 2/3 leads to Andrade creep, a relationship which is applicable to both polymers and metals. A comparison of the creep behavior of polymers and polycrystalline metals shows many points of similarity.
Novel polymerization methods. Introduction
Authors: Werber F. X. 
Published: December 2004

AbstractNew methods, new structures leading to novel properties are presented in a collection of summaries. Areas discussed were: thiosemicarbazides, organometallic initiation of allene polymerization, poly(1,1,4,4,‐tetramethyl‐1,3‐butadiene), emulsion polymerization of vinyl acetate with protein detergent solubilizing agents, alkali metal organic catalysts for stereospecific polymerization, anionic polymerization of dienes, rate constants in anionic polymerization, a series on polymerization by oxidative coupling with amine copper salt catalysts, block polymerization by vapor phase swelling, intra‐intermolecular propagation in the solid‐state and radiation induced polymerization.
Turbidimetric determination of the molecular weight distribution of linear polyethylene
Authors: Taylor W. C. , Tung L. H. 
Published: December 2004

Abstractα‐Chloronaphthalene plus 30 weight percent of dimethylphthalate was the solvent with 0.5% ethyl cellulose as stabilizer. A polymer concentration of 0.0025% gave optimum results. A parameter S which is defined as the difference in temperature between 20% and 50% of the total reduction in phototube output is related linearly to a parameter of the Wesslau distribution.
Identification of the urethane‐epoxy reaction product
Authors: Wood R. N. 
Published: December 2004

AbstractThe probable molecular structure resulting from a reaction of equal parts of a Bisphenol A/Epichlorohydrin epoxy and a Tolylene Diisocyanate Prepolymer with a selected diamine has been identified by using spectrometry. This identification presents additional opportunities for attaching other complex molecules to either of the basic resins. Not only can this technique lead to an interesting family of hybrid plastics, but it is another step toward designing specific molecules for specific applications.
Pyrolysis of phenolic polymers
Authors: Anderson Hugh C. 
Published: December 2004

AbstractThe technique of thermogravimetry was used to investigate the thermal decomposition characteristics of several cross‐linked phenolic polymers, which included regular and chlorinated phenolics and phenolics copolymerized with silane, nylon and phenol‐furfural resins. These polymers were found to be more stable thermally than the usual polyester and epoxide polymers, as evidenced by slower rates of decomposition and lower ultimate percentage weight losses. Temperatures at which 50% of ultimate percentage weight losses occurred ranged from 395°C for a phenolic copolymerized with a silane to 505°C for a chlorinated phenolic copolymerized with a silane. Chemical modification of the regular phenolic cross‐linked structure caused a decrease in thermal stability.
Some effects of molecular weight distribution on the melt rheology of high density polyethylene
Authors: Wagner H. L. , Wissbrun K. F. 
Published: December 2004

AbstractUsing a high shear rate capillary viscometer, the melt viscosities of a series of high density linear polyethylenes ranging in weight average molecular weight from 70,000 to 160,000 have been measured from shear rates of 2 to 200 sec−1 and from 190° to 240°C. The data, corrected for elastic end effects are described by an empirical relationship except for the temperature term which is fitted to the Williams‐Landel‐Ferry equation. Over the range measured the viscosity is given approximately by a power law in relation to shear rate with an exponent dependent upon molecular weight.The effects of distribution were examined by measuring the viscosity‐shear rate relationships for not only the above series, which varied in Mw/Mn from 23 to 10, but also for blends of polyethylenes of varying molecular weights or of fractions, and other polyethylenes obtained by removal of the high molecular weight tail. In general, the broader the distribution, the more sensitive is the viscosity to the rate of shear.The end correction, a measure of the elastic energy, does not vary much with shear stress or temperature in the case of high density polyethylene.
The analysis of polymers for moisture and volatiles
Authors: David D. J. , Baumann G. F. , Steingiser Samuel 
Published: December 2004

AbstractAn analytical method for the quantitative determination of the moisture and volatile content of polymeric materials is described. The method has been applied to polycarbonates, urethane elastomers and polyesters. It has been found particularly valuable for moisture determinations of polymers which have limited solubility in most common solvents and for polymers whose moisture content is in the range of 0.001%‐0.01%. The moisture is expelled from the sample by means of heating under vacuum and collected in a cold trap. The vapor pressure of the water is then measured and correlated with the amount present in the sample. Volatiles, if present, can be determined by difference after removal of the water. Commercially obtainable equipment is employed.
Photoelastic phenomena in plastics during impact
Authors: Hall N. W. , Wright R. E. , Smith W. C. 
Published: December 2004

AbstractThe study of strain patterns in deformed, transparent plastic placed between crossed Polaroids can shed considerable light on the responses of these plastics to stress. This article describes a study of the differing responses of three thermoplastics of varying degrees of toughness to the notched Izod impact test. The growth and waning of the strain patterns during impact are followed by means of high‐speed cinematography; interpretation of the phenomena thus observed is aided by thin section microscopy of partially deformed specimens.
Cellular materials–composition, cell‐size, thermal conductivity
Authors: Guenther Frederick O. 
Published: December 2004

AbstractComposition by weight and volume of a cellular material and how it changes with density is shown in the form of equations. The equations are used to derive the basic relationship between cell size, cell wall thickness, density of cellular material and density of solid and gaseous components. A simplified equation is presented for thermal conductivity of low density cellular materials. It is used to illustrate the contribution of the solid and gaseous components in cellular polystyrene and urethane at various densities. The contribution of factors other than conduction to observed thermal conductivity of cellular polystyrene is compared to that reported for fiber glass insulation. The observed effect of cell size on conductivity is presented and compared to the calculated effect, based on an equation in the literature.
Experimental measurement of roll‐separating forces during milling of plastics
Authors: Carey R. H. 
Published: December 2004

AbstractA “milling viscosity” test has been developed which measures the roll‐separating forces encountered during milling of experimental compound formulations on a carefully set‐up and controlled laboratory two‐roll mill. A small 8‐in. x 16‐in. laboratory mill was equipped with force‐measuring dynamometers and used to explore the actions of different vinyl‐resin compounds. The instrument has proven to be useful in developing thermoplastic materials, in providing an index for predicting the tendency of a material to deflect calender rolls, and as an aid in estimating the forces which may be encountered in full‐size equipment.
Polymer analysis, using gas chromatographic separation of pyrolyzates on a capacity column
Authors: Stanley C. W. , Peterson W. R. 
Published: December 2004

AbstractAn analytical method for polymer mixtures has been developed, using gas chromatographic separation of pyrolysis products on a capillary column. This technique uses one set of column conditions for the analysis of a number of polymers, including those from methyl methacrylate, ethyl acrylate, 2‐ethylhexyl acrylate, butadiene, acrylonitrile, vinyl acetate, and styrene, either as homopolymers on as copolymers of two or more components.