bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isothermal and nonisothermal crystallization of poly(aryl ether ketone ketone) with all‐para phenylene linkage
Authors: Wang Jiku , Yang Xiaoniu , Li Gao , Zhou Enle 
Published: October 2004

AbstractIsothermal and nonisothermal crystallization behavior for PEKK(T) was studied using differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and electron diffraction (ED). In the isothermal crystallization process, the Avrami parameters obtained were n = 2.33–2.69, which shows crystal growth of two‐dimensional extensions consistent with our observations by TEM. The lamellar thickness increases with the crystallization temperature of PEKK(T) crystallized isothermally from the melt. However, for the nonisothermal crystallization of PEKK(T), the results from the modified Avrami analysis show two different crystallization processes. Avrami exponents n1 = 3.61–5.30, obtained from the primary crystallization process, are much bigger than are the secondary n2 = 2.26–3.04 and confirmed by the observation of the spherulite morphology. PEKK(T) crystallized isothermally from the melt possesses the same crystal structure (Form I) as that from nonisothermal melt crystallization. The results from TEM observation show that the spherulite radius decreases with an increasing cooling rate. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3431–3438, 2001
Synthesis and characterization of poly{hexakis[(methyl)(4‐hydroxyphenoxy)]cyclotriphosphazene}
Authors: Luther Thomas A. , Stewart Frederick F. , Lash Robert P. , Wey John E. , Harrup Mason K. 
Published: October 2004

AbstractThe reaction of methylhydroquinone with hexachlorocyclotriphosphazene in the presence of a base, 4‐picoline, in cyclohexane was investigated. Nuclear magnetic resonance spectroscopy, multiangle laser light scattering, and elemental analyses were performed on the product and two other related phosphazene materials produced by analogous synthetic routes: poly[hexakis(4‐hydroxyphenoxy)cyclotriphosphazene] (1) and hexakis[(3‐tert‐butyl)(4‐hydroxyphenoxy)]cyclotriphosphazene (2). Unlike the data for 2 where the tert‐butyl moiety enforced regiospecific nucleophilic addition, the data for the methylhydroquinone‐substituted cyclotriphosphazene product indicate that the less sterically bulky methyl group provides only limited protection for the adjacent hydroxyl group. The result is the formation of a low molecular weight oligomer, poly{hexakis[(methyl)(4‐hydroxyphenoxy)]cyclotriphosphazene} (3), instead of a discrete cyclic trimer species. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3439–3446, 2001
High‐density polyethylene modified by polydimethylsiloxane
Authors: Muñoz P. MA. Patricia , Vargas Márcio D. , Werlang Moisés M. , Yoshida I. Valéria P. , Mauler Raquel S. 
Published: October 2004

AbstractHigh‐density polyethylene (HDPE) was modified by the grafting of polydimethylsiloxane (PDMS) through a free‐radical process, in a melt‐mixer chamber, using dicumyl peroxide (DCP) as an initiator. The influence of PDMS (0.2–0.8 mol %) and peroxide (0.03–0.08 mol %) concentrations on the grafting, final torque, and melt flow rate (MFR) of copolymers were investigated using factorial planning. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), MFR, and rheometry were used to characterize the copolymers obtained. Surface plots showed that higher degrees of grafted PDMS and higher final torques were obtained with increase in the PDMS amount at low DCP levels and with increase in the DCP amount at low PDMS levels. The peaks of fusion and crystallization of the copolymers showed no significant changes with respect to HDPE. Data of MFR and GPC suggested that crosslinking reactions and/or chain extension occurred concomitant with the grafting reactions. Copolymers with high grafting degrees showed high MFR and low dynamic shear viscosities in comparison with low grafting degree copolymers, which is probably due to the migration of the PDMS‐containing copolymers on the surface. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3460–3467, 2001
Hygrothermal aging of rubber modified and mineral filled dicyandiamide cured digylcidyl ether of bisphenol A epoxy resin. I. Diffusion behavior
Authors: Ivanova Katya I. , Pethrick Richard A. , Affrossman Stanley 
Published: October 2004

AbstractThe effect of hydration–dehydration cycling on the properties of a rubber modified, mineral filled epoxy resin is reported. This resin was based on diglycidyl ether of bisphenol A and cured with dicyandiamide. The material was aged in deionized water and a 5% (w/w) NaCl solution at 65°C. Gravimetric measurements, transmission electron microscopy, and diffusive reflectance IR Fourier transform spectroscopy were used to monitor the water sorption and physical and chemical changes occurring in the material. Two‐stage absorption was observed with deionized water, and the quasiequilibrium‐state water content was independent of the hygrothermal history. The equilibrium weight after dehydration depended on the hygrothermal history due to the presence of irreversibly absorbed water and leaching of material. The first stage of the absorption was found to be Fickian and was interpreted as being related to the process of saturation of the epoxy matrix. The driving force for the second stage was the osmotic pressure, and it was not observed when the material was aged in NaCl solution. The water caused irreversible damage to the resin through microcavity formation, and part of the water was molecularly dispersed in the epoxy matrix and part resided in microcavities. Absorption–desorption cycling resulted in an increased rate of absorption during subsequent rehydration. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3468–3476, 2001
Immobilization of cholesterol oxidase and potassium ferricyanide on dodecylbenzene sulfonate ion‐doped polypyrrole film
Authors: Kumar Arun , Rajesh  , Chaubey Asha , Grover S. K. , Malhotra B. D. 
Published: October 2004

AbstractDodecylbenzene sulfonate (DBS)‐doped polypyrrole (PPY) conducting polymer films were electrochemically deposited onto the indium‐tin‐oxide (ITO)‐coated glass plates in aqueous medium. The enzyme cholesterol oxidase (ChOx) was immobilized on these DBS–PPY films by a physical adsorption technique. These ChOx‐immobilized DBS–PPY films were characterized by ultraviolet–visible and Fourier transform infrared spectroscopy. The enzyme activity studies indicate that ∼40% of ChOx leaches out from the ChOx/DBS–PPY film. The ChOx activity in the ChOx/DBS–PPY film was assayed as a function of cholesterol concentration. The results of amperometric measurements conducted on ChOx/DBS–PPY/ITO film show linearity over the range 2–8 mM of cholesterol solution. The ChOx/DBS–PPY/ITO electrodes exhibit a response time of 30 s and are stable for ∼3 months at 4 °C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3486–3491, 2001
Miscibility of polystyrene‐based ionomers with poly(2,6‐dibromo‐1,4‐phenylene oxide)
Authors: Alkan Cemil , Aras Leyla 
Published: October 2004

AbstractBlends of poly(2,6‐dibromo‐1,4‐phenylene oxide) (PDBrPO) with 4.8 mol % sulfonated polystyrene (4.8SPS), Na‐neutralized 1.7 mol % sulfonated polystyrene (Na1.7SPS), Mn‐neutralized 3.8 mol % sulfonated polystyrene (Mn3.8SPS), and Zn‐neutralized 3.8 mol % sulfonated polystyrene (Zn3.8SPS) ionomers were investigated for their miscibilities with varying compositions by dilute solution viscometry (DSV), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). Δb, μ, and α parameters by W. R. Krigbaum and F. J. Wall (J Polym Sci 1950, 5, 505), K. K. Chee (Eur Polym J 1990, 4, 423), and Z. Sun et al. (Eur Polym J 1992, 28, 1259), respectively, were calculated from DSV data to determine miscibility. Na1.7SPS is immiscible with PDBrPO in no relation to the blend compositions. On the other hand, the increasing extent of miscibility of the blends reflected by the data is as follows: 4.8SPS < Mn3.8SPS < Zn3.8SPS. DSC and SEM results are also in agreement with the DSV data except for the α parameter, which showed some disagreements with Δb and μ parameters in a few blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3558–3567, 2001
Physicochemical characterization of hydrogels based on polyvinyl alcohol–vinyl acetate blends
Authors: Cauich–Rodríguez J. V. , Deb S. , Smith R. 
Published: October 2004

AbstractHydrogels made of polyvinyl alcohol–vinyl acetate and its blends with water soluble polymer were studied in terms of swelling behavior, microstructure, and dynamic mechanical properties. Hydrogels prepared by blending polyvinyl alcohol–vinyl acetate with either polyacrylic acid or poly(4‐vinyl pyridine) exhibited a strong pH dependency. When poly(vinyl pyrrolidone) was used for blending, an unusual pH dependency was observed. An increase in the equilibrium water content in all systems resulted in an increase in the freezable water as determined by DSC. Critical point drying led to a striated surface on polyacrylic acid–polyvinyl alcohol–vinyl acetate hydrogels, whereas a porous structure was observed on the freeze‐dried poly(vinyl pyrrolidone)–polyvinyl alcohol–vinyl acetate gels. Hydrogels with elevated storage modulus were obtained when either polyvinyl alcohol–vinyl acetate alone or polyacrylic acid–polyvinyl alcohol–vinyl acetate blends were thermally treated at high temperatures (i.e., 150°C). Low storage modulus was observed for both poly(vinyl pyrrolidone) and poly(4‐vinyl pyridine)‐containing hydrogels. Temperature dependency of storage modulus from 20 to 60°C was observed only for poly(4‐vinyl pyridine)–polyvinyl alcohol–vinyl acetate hydrogels. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3578–3590, 2001
Phase segregation behavior in PE/DOP blends and glass‐transition temperatures of polyethylene
Authors: Shieh Yeong‐Tarng , Liu Chih‐Ming 
Published: October 2004

AbstractPhase segregation behavior in PEs/DOP blends, interactions between PEs and DOP, and glass‐relaxation transitions of PEs were investigated. FTIR, DSC, and TGA data demonstrated that molecular interactions were present between PEs and DOP. DMA data demonstrated that pure PEs each (except HDPE) exhibited two loss maxima at about −20 and −120°C but the PEs/DOP blends (including the HDPE/DOP blend) yielded one new loss maximum at about −60°C. The glass‐relaxation transitions corresponding to the three loss maxima on the DMA curves were designated α (−20°C), β (−60°C), and γ (−120°C) transitions and were attributed to the relaxation of the amorphous phases in the interlamellar, interfibrillar, and interspherulitic regions, respectively, based on DMA, WAXD, SAXS, and POM measurements. The controversial Tg values of PEs and their origin were thus clarified in this study. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3591–3601, 2001
Growth and development of Encarsia formosa (Hymenoptera: Aphelinidae) in the greenhouse whitefly, Trialeurodes vaporariorum (Homoptera: Aleyrodidae): Effect of host age
Authors: Hu Jing S. , Gelman Dale B. , Blackburn Michael B. 
Published: October 2004

AbstractThe tiny parasitoid wasp, Encarsia formosa, has been used successfully to control greenhouse whiteflies (GHWFs) in greenhouses in many countries throughout the world. Therefore, there has been considerable interest in developing methods for artificially rearing this wasp. However, little information is available concerning the regulation of its development including the host‐parasitoid interactions that are required for the parasitoid to complete its life cycle. Here we confirm that parasitoid developmental rates differ significantly based upon the host instar parasitized. Development was faster when 3rd and 4th instar GHWFs were offered for parasitization than when 1st or 2nd instars were used. Our results show that it is primarily the embryo and the first two parasitoid instars that exhibit prolonged developmental times when 1st and 2nd instar whiteflies are parasitized. Although percent emergence was not affected by host age at the time of parasitization, adult longevity as well as adult emergence pattern varied greatly depending upon the instar parasitized. When 3rd and 4th instar GHWFs were selected for oviposition, adult wasps lived significantly longer than when 1st or 2nd instars were used; also, there was a sharp emergence peak on the 2nd day after emergence was first observed (reduced or absent when 1st or 2nd instar GHWFs were parasitized) and the emergence period was reduced from between 8 and 11 days to 5 days. In general, the younger the host instar parasitized, the less synchronous was parasitoid development. Previous reports that E. formosa will not molt to the 2nd instar until the host has reached its 4th instar were not confirmed. When 1st instar host nymphs were parasitized, 2nd instar parasitoids were detected in 3rd instar hosts. Importantly, however, no matter which instar was parasitized, the parasitoid never molted to its last instar until the host had reached Stage 5 of its last instar, a stage in which host pharate adult formation has been initiated. It appears, then, that a condition(s) associated with host pharate adult formation is required for the parasitoid’s final larval molt. Results reported here should facilitate the development of in vitro rearing systems for E. formosa.Arch. Insect Biochem. Physiol. 49:125–136, 2002. Published 2002 Wiley‐Liss, Inc.
Local expression and distribution of a storage protein in the ovary ofHyphantria cunea
Authors: Cheon Hyang‐Mi , Kim Hong‐Ja , Chung Duck‐Hwa , Kim Myeong‐Ok , Park Joong‐Suk , Yun Chi‐Young , Seo Sook‐Jae 
Published: October 2004

AbstractStorage protein‐1 (HcSP‐1) is a major storage protein found in the hemolymph and fat body ofHyphantria cunea. HcSP‐1 has a high methionine (6.0%) and low aromatic amino acid content (8.5%) (Cheon et al., 1998). In this study, the accumulation and expression of HcSP‐1 in ovary was investigated using biochemical and immunocytochemical methods. HcSP‐1 was detected in the ovaries in 6‐day‐old pupae and accumulated toward the end of pupal life, when HcSP‐1 transcripts were detectable by Northern blot analysis and RT‐PCR. In situ hybridization showed that the HcSP‐1 mRNA was located in the nurse cells and follicular epithelial cells, but not in the oocyte. Though most of the HcSP‐1 that is incorporated in the yolk bodies of the oocyte is probably sequestered from the surrounding hemolymph, HcSP‐1 is an important yolk protein contributing to early yolk body formation before the development of patency by the follicular epithelium. Arch. Insect Biochem. Physiol. 48:111–120, 2001. © 2001 Wiley‐Liss, Inc.
Influence of alternating low frequency magnetic fields on reactivity of central dopamine receptors in neonatal 6‐hydroxydopamine treated rats
Authors: Sieroń Aleksander , Brus Ryszard , Szkilnik Ryszard , Plech Andrzej , Kubański Norbert , Cieślar Grzegorz 
Published: October 2004

AbstractThe aim of this study was to evaluate the influence of extremely low frequency magnetic field (ELF MF) on the reactivity of the central dopamine D1 receptor in rats with dopamine neurons chemically damaged by 6‐hydroxydopamine (6‐OHDA), an animal model of human's Parkinson's disease. The experiment was carried out on male Wistar rats. On day 3 of postnatal life, a lasting and selective chemical damage of the central dopamine system was induced in the rats by infusion of 6‐OHDA HBr (133.4 μg intracerebroventricular, base form) given bilaterally into lateral ventricles of the brain. Control animals received similar treatments injecting only vehicle. At 2 months of age, both 6‐OHDA treated and control rats were randomly divided into two groups. Rats from the first group were exposed to 10 Hz sinusoidal, 1.8–3.8 mT magnetic field one hour daily for 14 days. Rats of the second group were sham exposed, with the applicator solenoid turned off. On the day after the final exposure the evaluations were made of the rat's spontaneous irritability, oral activity, and catalepsy. The MF exposed rat with chemically induced dopamine neurons damage exhibited a reduction of irritability and oral activity when stimulated with SKF 38393 (the agonist of central dopamine D1 receptor) and some increase of catalepsy after administration of SCH 23390(the antagonist of central dopamine D1 receptor). These results indicate that ELF MF reduce the reactivity of central dopamine D1 receptors in rats. Bioelectromagnetics 22:479–486, 2001. © 2001 Wiley‐Liss, Inc.
Pulsed electromagnetic fields affect the intracellular calcium concentrations in human astrocytoma cells
Authors: Pessina G.P. , Aldinucci C. , Palmi M. , Sgaragli G. , Benocci A. , Meini A , Pessina F. 
Published: October 2004

AbstractExperiments assessed whether long term exposure to 50 Hz pulsed electromagnetic fields with a peak magnetic field of 3 mT can alter the dynamics of intracellular calcium in human astrocytoma U‐373 MG cells. Pretreatment of cells with 1.2 μM substance P significantly increased the [Ca2+]i. The same effect was also observed when [Ca2+]i was evaluated in the presence of 20 mM caffeine. After exposure to electromagnetic fields the basal [Ca2+]i levels increased significantly from 143 ± 46 nM to 278 ± 125 nM. The increase was also evident after caffeine addition, but in cells treated with substance P and substance P + caffeine we observed a [Ca2+]i decrease after exposure. When we substituted calcium‐free medium for normal medium immediately before the [Ca2+]i measurements, the [Ca2+]i was similar to that measured in the presence of Ca2+. In this case, after EMFs exposure of cells treated with substance P, the [Ca2+]i, measured without and with addition of caffeine, declined from 824 ± 425 to 38 ± 13 nM and from 1369 ± 700 to 11 ± 4 nM, respectively, indicating that electromagnetic fields act either on intracellular Ca2+ stores or on the plasma membrane. Moreover the electromagnetic fields that affected [Ca2+]i did not cause cell proliferation or cell death and the proliferation indexes remained unchanged after exposure. Bioelectromagnetics 22:503–510, 2001. © 2001 Wiley‐Liss, Inc.
Solutions and linearization of the nonlinear dynamics of radiation damping
Authors: Rourke David E. 
Published: October 2004

AbstractThe techniques of Painlevé analysis and Lie algebra analysis were applied to the nonlinear Bloch equations with radiation damping. Painlevé analysis is useful in finding when explicit solutions exist to a nonlinear system. It was applied to the radiation‐damped system with damping time Tr, and with T1 and T2 relaxation, but with no externally applied radiofrequency (RF) pulse. Two cases were identified where explicit solutions could be found. The first case (1/T1=0) is well known, the second case (1/T1=1/Tr + 1/T2) is apparently not previously known. Lie algebra analysis was used to show that the system with no relaxation, but with an externally applied RF pulse, could be transformed into a linear system. This simplifies the forward problem of finding the magnetization response to a given pulse. It also allows the inverse problem to be solved, where the pulse is calculated to result in a given magnetization response as functions of both resonance offset and radiation damping time. © 2002 Wiley Periodicals, Inc. Concepts Magn Reson 14: 112–129, 2002
Macroscopic molecular diffusion in liquid NMR, revisited
Authors: Jeener J. 
Published: October 2004

AbstractThis paper has three independent parts. First, Torrey's treatment of molecular diffusion in NMR is directly extended to polyatomic molecules by the introduction of a position‐dependent average density operator. Second, some improvement is proposed for the study of “abnormal” diffusion by spin–echo experiments, by directly answering the following question: “Which statistical properties of the molecular motion are directly measured in simple spin–echo experiments”? Third, a simple numerical technique is proposed for the prediction of the effects of diffusion in spin echo experiments of the CRAZED type, in which the relevant dipolar field inhomogeneities have the spatial periodicity of the magnetization helix. © 2002 Wiley Periodicals, Inc. Concepts Magn Reson 14: 79–88, 2002
Michel‐Eugène Chevreul: From laws and principles to the production of colour plates
Authors: Viénot Françoise 
Published: October 2004

AbstractMichel‐Eugène Chevreul (1786–1889) did major scientific work in the fields of chemistry and colour and pioneered the study of simultaneous contrast. His book De la loi du contraste simultané des couleurs (The Principles of Harmony and Contrast of Colours) was published in 1839. Here, his studies pertained to simultaneous contrast, when two or more colours seen contiguously are influenced in brightness and/or in hue, and on successive contrast, when afterimages modify colour perception. He also investigated the mixed contrast that appeared in tapestries in which a mixture of colours was obtained by the plying of yarn or by hatching. Later, he reported on the influence exerted on vision by coloured objects in circular motion around an axis perpendicular to their plane (1879). Many examples and numerous experimental checks documented in his books supported his demonstration of contrast. Of particular interest are the colour plates attached to the books. Another significant work by Chevreul was a three‐dimensional colour classification system (1864), after which he manufactured a colour atlas showing colour circles and monochrome lightness scales. Data are presented from recent measurements of Chevreul's atlas circles and plates, and there is a discussion of his choice of complementary colours. © 2002 John Wiley & Sons, Inc. Col Res Appl, 27, 4–14, 2002
Overtraining in back‐propagation neural networks: A CRT color calibration example
Authors: Alman David H. , Ningfang Liao 
Published: October 2004

AbstractA condition of overtraining a back‐propagation neural network exists when excessive model degrees of freedom are used in network training. A CRT color calibration experiment was done to illustrate methods to avoid an overtrained condition in model development. Cross‐validation, in which the experimental data are split into parameter‐training and independent‐test data sets, is advocated. © 2002 Wiley Periodicals, Inc. Col Res Appl, 27, 122–125, 2002; DOI 10.1002/col.10027