bluuebunny/crossref_metadata_2025_split huggingface dataset:
Compatibility of polysaccharide/maleic copolymer blends. IV. Thermal behavior of hydroxypropyl cellulose‐containing blends
Authors: Bumbu Gina‐Gabriela , Vasile Cornelia , Popescu Maria Cristina , Darie Hristea , Charlotte Chiţanu Gabrielle , Singurel Gheorghe , Carpov Adrian 
Published: March 2003

AbstractThe compatibility of the hydroxypropyl cellulose (HPC) with maleic acid–vinyl acetate copolymer in the solid state was studied by thermogravimetry, thermo‐optical analysis, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and optical microscopy. It was established that physical interactions are prevalent in blends with a high content of HPC, whereas chemical interactions predominate in blends with a medium and low content of HPC. By increasing the temperature, the thermochemical reactions are favored. Thermal properties are dependent on the mixing ratio of the components. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2585–2597, 2003
Low dielectric thermoset. I. Synthesis and properties of novel 2,6‐dimethyl phenol‐dicyclopentadiene epoxy
Authors: Hsuan Lin Ching , Chung Chiang Jung , Shan Wang Chun 
Published: March 2003

AbstractA 2,6‐dimethyl phenol‐dicyclopentadiene novolac was synthesized from dicyclopentadiene and 2,6‐dimethyl phenol, and the resultant 2,6‐dimethyl phenol‐dicyclopentadiene novolac was epoxidized to 2,6‐dimethyl phenol‐dicyclopentadiene epoxy. The structures of novolac and epoxy were confirmed by Fourier transform infrared spectroscopy (FTIR), elemental analysis, mass spectroscopy (MS), nuclear magnetic resonance spectroscopy (NMR), and epoxy equivalent weight titration. The synthesized 2,6‐dimethyl phenol‐dicyclopentadiene epoxy was then cured with 4,4‐diaminodiphenyl methane (DDM), phenol novolac (PN), 4,4‐diaminodiphenyl sulfone (DDS), and 4,4‐diaminodiphenyl ether (DDE). Thermal properties of cured epoxy resins were studied by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), dielectric analysis (DEA), and thermal gravimetric analysis (TGA). These data were compared with those of the commercial bisphenol A epoxy system. Compared with the bisphenol A epoxy system, the cured 2,6‐dimethyl phenol‐ dicyclopentadiene epoxy resins exhibited lower dielectric constants (∼3.0 at 1 MHz and 2.8 at 1 GHz), dissipation factors (∼0.007 at 1 MHz and 0.004 at 1 GHz), glass transition temperatures (140–188°C), thermal stability (5% degradation temperature at 382–404°C), thermal expansion coefficients [50–60 ppm/°C before glass‐transition temperature (Tg)], and moisture absorption (0.9–1.1%), but higher modulus (∼2 Gpa at 60°C). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2607–2613, 2003
Mechanical and viscoelastic behavior of natural rubber and carboxylated styrene‐butadiene rubber latex blends
Authors: Stephen Ranimol , Raju K. V. S. N. , Nair Sobha V. , Varghese Siby , Oommen Zachariah , Thomas Sabu 
Published: March 2003

AbstractThe morphology, mechanical and viscoelastic behavior of latex blends of unvulcanized natural rubber (NR) with carboxylated styrene‐butadiene rubber (XSBR) were investigated, with special reference to the effect of the blend ratio, temperature, and frequency. Mechanical properties like tensile strength, modulus, and elongation at break were also studied. As the XSBR content increased, the tensile strength increased up to a 50:50 NR/XSBR ratio and then decreased as a result of the self‐curing nature of XSBR. The dynamic mechanical properties of these latex blends were analyzed for loss tangent, storage modulus, and loss modulus. The entire blend yielded two glass‐transition temperatures, which corresponded to the transitions of individual components, indicating that the system was immiscible. To determine the change in modulus with time, a master curve of 50:50 NR/XSBR blends was plotted. Time–temperature superposition and Cole–Cole analysis were done to understand the phase behavior of the latex blends. The experimental and theoretical values of storage modulus of blends were compared using the Kerner and Halpin–Tsai models. With the help of optical micrographs, attempts were made to correlate the morphology and viscoelastic behavior of these blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2639–2648, 2003
Modeling of poly(L‐lactide) thermal degradation: Theoretical prediction of molecular weight and polydispersity index
Authors: Yu Hengxing , Huang Nanxun , Wang Chaosheng , Tang Zhilian 
Published: March 2003

AbstractA mathematical model to describe the molecular weight and polydispersity index (Q) in poly(L‐lactide) (PLLA) thermal degradation has been developed. Based on the random chain scission mechanism, effects of temperature and time on the molecular weight and polydispersity index are included in this model. It incorporates the degradation and recombination reaction of PLLA thermal degradation, while taking into account the equal probability assumption. The developments of molecular weight and polydispersity index of PLLA polymer in the thermal degradation process were investigated at temperature ranging from 180–220°C, the experimental data show PLLA reaches its thermal degradation equilibrium in 2 h. The simulated results of this model are compared with the measured molecular weight and polydispersity index of the PLLA polymer. The changes of the molecular weight and polydispersity index in the PLLA thermal degradation can be predicted by this model. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2557–2562, 2003
Thermal characteristics of IPNs composed of poly(propylene glycol) and poly(acrylic acid)
Authors: Jeong Kim Seon , Jung Lee Ki , Min Lee Sang , Young Kim In , Moo Lee Young , Kim Sun I. 
Published: March 2003

AbstractInterpenetrating polymer networks (IPNs) based on poly(propylene glycol) (PPG) and poly(acrylic acid) (PAAc) were prepared by UV irradiation and characterized using fourier transform infrared (FTIR), differential scanning calorimetry (DSC), dielectric analysis (DEA), and thermogaravimetry (TGA). The glass transition temperatures (Tgs) of these IPNs exhibited a relatively higher temperature with an increased PAAc content. The decomposition temperature of PAAc is lower than that of PPG. PAAc affects the thermal stability of IPN more than PPG. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2570–2574, 2003
Preparation of a novel poloxamer hydrogel
Authors: Kweon HaeYong , Yoo Mi‐Kyong , Lee Jin‐Hak , Wee Won‐Ryang , Han Young‐Gun , Lee Kwang‐Gill , Cho Chong‐Su 
Published: March 2003

AbstractPoloxamer hydrogels were prepared by photopolymerization from poloxamer macromer, which was synthesized by reaction of poloxamer 407 with acryloyl chloride. The synthesis of poloxamer macromer was confirmed using NMR and FTIR spectrometry. The gelation behavior and crystalline structure of poloxamer macromer was similar to those of poloxamer 407 itself; however, the amorphous scattering of poloxamer macromer was higher than that of poloxamer itself. Differential scanning calorimetric analysis showed that the melting temperature and enthalpy of poloxamer hydrogel were also lower than those of poloxamer itself. The compressive modulus of poloxamer hydrogels were similar (92.6–101.7 kPa), regardless of the concentration of poloxamer macromer. Equilibrium water uptake of poloxamer hydrogels decreased with an increase of concentration of poloxamer macromer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2670–2676, 2003
Reactivity, chemical structure, and molecular mobility of urea–formaldehyde adhesives synthesized under different conditions using FTIR and solid‐state 13C CP/MAS NMR spectroscopy
Authors: Park Byung‐Dae , Kim Yoon Soo , Singh Adya P. , Lim Kie Pyo 
Published: March 2003

AbstractThis study was conducted to investigate the effects of reaction pH condition and hardener type on the reactivity, chemical structure, and molecular mobility of urea–formaldehyde (UF) resins. Three different reaction pH conditions, such as alkaline (7.5), weak acid (4.5), and strong acid (1.0), were used to synthesize UF resins, which were cured by adding four different hardeners (ammonium chloride, ammonium sulfate, ammonium citrate, and zinc nitrate) to measure gel time as the reactivity. FTIR and 13C‐NMR spectroscopies were used to study the chemical structure of the resin prepared under three different reaction pH conditions. The gel time of UF resins decreased with an increase in the amount of ammonium chloride, ammonium sulfate, and ammonium citrate added in the resins, whereas the gel time increased when zinc nitrate was added. Both FTIR and 13C‐NMR spectroscopies showed that the strong reaction pH condition produced uronic structures in UF resin, whereas both alkaline and weak‐acid conditions produced quite similar chemical species in the resins. The proton rotating‐frame spin–lattice relaxation time (T1ρH) decreased with a decrease in the reaction pH of UF resin. This result indicates that the molecular mobility of UF resin increases with a decrease in the reaction pH used during its synthesis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2677–2687, 2003
Permselectivities of 2,2′‐dimethyl‐4,4′‐bis(aminophenoxyl)biphenyl diphenyl methane–based aromatic polyamide membranes for aqueous alcohol mixtures in pervaporation and evapomeation
Authors: Fan Shu‐Chin , Wang Yi‐Chieh , Li Chi‐Lan , Lee Kueir‐Rarn , Liaw Der‐Jang , Lai Juin‐Yih 
Published: March 2003

AbstractThe separation of aqueous alcohol mixtures was carried out by use of a series of novel aromatic polyamide membranes. The aromatic polyamides were prepared by the direct polycondensation of 2,2′‐dimethyl‐4,4′‐bis(aminophenoxyl)biphenyl (DBAPB) with various aromatic diacids, such as terephthalic acid (TPAc), 5‐tert‐butylisophthalic acid (TBPAc), and 4,4′‐hexafluoroisopropylidenedibenzoic acid (FDAc). The pervaporation and evapomeation performance of these novel aromatic polyamide membranes for dehydrating aqueous alcohol solution were investigated. The solubility of ethanol in the aromatic polyamide membranes is higher than that of water, but the diffusivity of water through the membrane is higher than that of ethanol. The effect of diffusion selectivity on the membrane separation performances plays an important role in the evapomeation process. Compared with pervaporation, evapomeation effectively increases the permselectivity of water. Moreover, the effect of aromatic diacids on the polymer chain packing density, pervaporation, and evapomeation performance were investigated. It was found that the permeation rate could be increased by introduction of a bulky group into the polymer backbone. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2688–2697, 2003
Optical properties of injection‐molded polystyrene scintillators. I. Processing and optical properties
Authors: Martins J. A. , Seixas J. , Silva J. , Esteves V. , Oliveira M. J. , Gomes J. , Maio A. , Pouzada A. S. 
Published: March 2003

AbstractScintillating tiles for the Tilecal/Atlas calorimeter can be produced by injection molding, an alternative to mold casting via in situ polymerization. This new production method, which leads to a much faster production rate, introduces a number of additional variables that affect the optical yield of the scintillators and that have not yet been reported in the literature. In this work, the effect of processing‐induced orientation on the optical properties of the scintillators is analyzed and discussed. For this purpose, the birefringence across the thickness of the scintillator has been measured. The variations of the birefringence may be correlated with the orientation and, therefore, related to the optical performance, that is, the average light output and its nonuniformity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2706–2713, 2003
Synthesis and polymerization of a new iodine‐containing monomer
Authors: Lakshmi S. , James Nirmala R. , Nisha V. S. , Jayakrishnan A. 
Published: March 2003

AbstractA new iodine‐containing methacrylate monomer, 3,4,5‐triiodobenzoyloxyethyl methacrylate (TIBEM), was synthesized by coupling 2‐hydroxyethyl methacrylate (HEMA) with 3,4,5‐triiodobenzoic acid. The monomer was characterized by 1H nuclear magnetic resonance, infrared (IR), and ultraviolet spectra. Homopolymerization and copolymerization of the monomer with methyl methacrylate (MMA) were carried out using 2,2′‐azobis isobutyronitrile as the initiator. A terpolymer of TIBEM, MMA, and HEMA was also synthesized. The copolymers were characterized by IR, gel permeation chromatography, differential thermal analysis, and thermogravimetric analysis (TGA). High molecular weight polymers were produced with MMA at different feed compositions of TIBEM. The polymers were found to be freely soluble in common solvents for acrylic polymers. TGA showed little decomposition of the copolymer below 280°C. Copolymers showed good radiopacity at 25 wt % of TIBEM in the feed. These copolymers could find applications in medical and dental areas where radiopacity is a desirable feature of the implants. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2580–2584, 2003
Pulsed electromagnetic fields prevent osteoporosis in an ovariectomized female rat model: A prostaglandin E2‐associated process
Authors: Chang Kyle , Chang Walter Hong‐Shong 
Published: March 2003

AbstractWith the use of Helmholtz coils and pulsed electromagnetic field (PEMF) stimulators to generate uniform time varying electromagnetic fields, the effects of extremely low frequency electromagnetic fields on osteoporosis and serum prostaglandin E2 (PGE2) concentration were investigated in bilaterally ovariectomized rats. Thirty‐five 3 month old female Sprague–Dawley rats were randomly divided into five different groups: intact (INT), ovariectomy (OVX), aspirin treated (ASP), PEMF stimulation (PEMF + OVX), and PEMF stimulation with aspirin (PEMF + ASP) groups. All rats were subjected to bilateral ovariectomy except those in INT group. Histomorphometric analyses showed that PEMF stimulation augmented and restored proximal tibial metaphyseal trabecular bone mass (increased hard tissue percentage, bone volume percentage, and trabecular number) and architecture (increased trabecular perimeter, trabecular thickness, and decreased trabecular separation) in both PEMF + OVX and PEMF + ASP. Trabecular bone mass of PEMF + OVX rats after PEMF stimulation for 30 days was restored to levels of age matched INT rats. PEMF exposure also attenuated the higher serum PGE2 concentrations of OVX rats and restored it to levels of INT rats. These experiments demonstrated that extremely low intensity, low frequency, single pulse electromagnetic fields significantly suppressed the trabecular bone loss and restored the trabecular bone structure in bilateral ovariectomized rats. We, therefore, conclude that PEMF may be useful in the prevention of osteoporosis resulting from ovariectomy and that PGE2 might relate to these preventive effects. Bioelectromagnetics 24:189–198, 2003. © 2003 Wiley‐Liss, Inc.
Effects of high power microwave pulses on synaptic transmission and long term potentiation in hippocampus
Authors: Pakhomov Andrei G. , Doyle Joanne , Stuck Bruce E. , Murphy Michael R. 
Published: March 2003

AbstractEffects of short, extremely high power microwave pulses (EHPP) on neuronal network function were explored by electrophysiological techniques in the isolated rat hippocampal slice model. Population spikes (PS) in the CA1 area were evoked by repeated stimulation (1 per 30 s) of the Schaffer collateral pathway. A brief tetanus (2 s at 50 Hz) was used to induce long term potentiation (LTP) of synaptic transmission. In three different series of experiments with a total of 160 brain slices, the EHPP irradiation was performed before, during, or after the tetanus. The EHPP carrier frequency was 9.3 GHz, the pulse width and repetition rate were from 0.5 to 2 μs and from 0.5 to 10 Hz, respectively, and the peak specific absorption rate (SAR) in brain slices reached up to 500 MW/kg. Microwave heating of the preparation ranged from 0.5 °C (at 0.3 kW/kg time average SAR) to 6 °C (at 3.6 kW/kg). The experiments established that the only effect caused by EHPP exposure within the studied range of parameters was a transient and fully reversible decrease in the PS amplitude. Recovery took no more than a few minutes after the cessation of exposure and return to the initial temperature. This effect's features were characteristic of an ordinary thermal response: it was proportional to the temperature rise but not to any specific parameter of EHPP, and it could also be induced by a continuous wave (CW) irradiation or conventional heating. Irradiation did not affect the ability of neurons to develop LTP in response to tetanus or to retain the potentiated state that was induced before irradiation. No lasting or delayed effects of EHPP were observed. The results are consistent with the thermal mechanism of EHPP action and thus far provided no indication of EHPP‐specific effects on neuronal function. Bioelectromagnetics 24:174–181, 2003. Published 2003 Wiley‐Liss, Inc.
Whole body exposure of rats to microwaves emitted from a cell phone does not affect the testes
Authors: Dasdag Suleyman , Zulkuf Akdag M. , Aksen Feyzan , Yılmaz Fahri , Bashan Mehmet , Mutlu Dasdag M. , Salih Celik M. 
Published: March 2003

AbstractThe objective of this study was to investigate the effects of radiofrequency radiation emitted from cellular phones on the lipid composition, malondialdehyde concentration, p53 immune reactivity, sperm count, morphology, histological structure of testes, and on rectal temperature of rats exposed to microwave radiation emitted from cellular phones. Sixteen Spraque–Dawley rats were separated into two groups of eight, sham exposed (control) and experimental. The rats were confined in plexiglas cages specially designed for this study, and cellular phones were placed 0.5 cm under the cages. For the experimental group, cellular phones were activated 20 min per day (7 days a week) for 1 month. For the control group, the cellular phones were placed beneath the cages for 20 min a day, but the phones were turned off. Rectal temperatures were measured weekly. For 250 mW radiated power, the whole body average SAR (rms) is 0.52 W/kg and 1 g averaged peak SAR (rms) is 3.13 W/kg. The Mann–Whitney U‐test was used for statistical comparisons of groups. No statistically significant alteration in any of the endpoints was noted. This study found no evidence suggesting an adverse effect of cell phone exposure on measures of testicular function or structure. Bioelectromagnetics 24:182–188, 2003. © 2003 Wiley‐Liss, Inc.
Extracellular currents alter gap junction intercellular communication in synovial fibroblasts
Authors: Marino Andrew A. , Kolomytkin Oleg V. , Frilot Clifton 
Published: March 2003

AbstractWe studied the effect of extremely low frequency (ELF) currents on gap junction intercellular communication (GJIC) mediated by connexin43 protein. Confluent monolayers of synovial fibroblasts (HIG‐82) and neuroblastoma cells (5Y) were exposed in bath solution to 0–75 mA/m2 (0–56 mV/m), 60 Hz. Single channel conductance, cell membrane current‐voltage (I‐V) curves, and Ca2+ influx were measured using the nystatin single and double patch methods. The conductances of the closed and open states of the gap junction channel in HIG‐82 cells were each significantly reduced (by 0.76 and 0.39 pA, respectively) in cells exposed to 20 mA/m2. Current densities as low as 10 mA/m2 significantly increased Ca2+ influx in HIG‐82 cells. No effects were seen in 5Y cells. The I‐V curves of the plasma membranes of both types of cells were independent of 60 Hz electric fields and current densities, 0–75 mA/m2, indicating that the effect of the 60 Hz fields on GJIC in HIG‐82 cells was not mediated by a change in membrane potential. We conclude that ELF electric fields can alter GJIC in synovial cells via a mechanism that does not depend on changes in membrane potential, but may depend on Ca2+ influx. The results open the possibility that GJIC mediated responses in synovial cells, such as for example, their secretory responses to proinflammatory cytokines, could be antagonized by the application of ELF electric fields. Bioelectromagnetics 24:199–205, 2003. © 2003 Wiley‐Liss, Inc.
Elevated residential exposure to power frequency magnetic field associated with greater average age at diagnosis for patients with brain tumors
Authors: Li Chung‐Yi , Lin Ruey S. , Sung Fung‐Chang 
Published: March 2003

AbstractTo explore whether the age at cancer diagnosis was associated with residential exposure to magnetic field, we compared average ages at diagnosis for cases of leukemia, brain tumor, or female breast cancer with elevated exposure (magnetic flux density ≥ 0.2 μT, or residential distance from major power lines ≤ 100 m) to average ages at diagnosis for cancer cases with same diagnoses but with a background exposure (< 0.2 μT or > 100 m from major power lines). Comparing with brain tumor cases with background magnetic field exposure (n = 506), brain tumor cases with elevated exposure (n = 71) were 6 years older on average at diagnosis (P = 0.01). The difference was greater for males (45.2 vs. 52.1 years, P = 0.01) than for females (44.3 vs. 48.2 years, P = 0.27). No such phenomena at a significant level was observed for leukemia, female breast cancer, or a random sample of general population. We noted an association between magnetic field exposure and a greater mean age at diagnosis for brain tumors. Whether or not these phenomena suggest a delayed occurrence of brain tumors following a higher than background residential magnetic field exposure deserves further investigation. Bioelectromagnetics 24:218–221, 2003. © 2003 Wiley‐Liss, Inc.
Effect of coexposure to 50 Hz magnetic fields and an aneugen on human lymphocytes, determined by the cytokinesis block micronucleus assay
Authors: Verheyen G.R. , Pauwels G. , Verschaeve L. , Schoeters G. 
Published: March 2003

AbstractInterference of 50 Hz extremely low frequency magnetic fields (ELF‐MF) with the known aneugen vinblastine (VBL) on micronucleus formation was tested with the in vitro cytokinesis block micronucleus assay in human lymphocyte cultures. Isolated lymphocyte cultures were prepared from 18 individuals. Three groups of quadruplicate cultures from six unrelated individuals were exposed to 50 Hz ELF‐MF of background (bkg), 80 and 800 μT, respectively, during the complete incubation period (72 h). Twenty‐four hours after culture initiation, one replicate culture from each individual within each ELF‐MF group was exposed to 0, 5, 10, or 15 ng/ml VBL. The isolated lymphocyte cultures were scored for the presence of micronuclei, the nuclear division index (NDI), and apoptosis. As expected, increased VBL concentration resulted in an increased micronucleus and apoptosis frequency and in a decreased NDI. In the presence of VBL, there was a systematic tendency for increased micronucleus and apoptosis frequency in the ELF‐MF exposed groups compared to the bkg group. In the absence of VBL, we observed no statistically significant effect of ELF‐MF on micronucleus induction or apoptosis frequency, but the NDI was significantly higher in the 800 μT group compared to the other groups, suggesting an effect of ELF‐MF on cell proliferation. An interaction between ELF‐MF and VBL on NDI was observed. This interaction reflected the drastic decrease in NDI due to coexposure to VBL. Bioelectromagnetics 24:160–164, 2003. © 2003 Wiley‐Liss, Inc.