bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activation energy and curing behavior of resol‐ and novolac‐type phenolic resins by differential scanning calorimetry and thermogravimetric analysis
Authors: Lee Young‐Kyu , Kim Dae‐Jun , Kim Hyun‐Joong , Hwang Teak‐Sung , Rafailovich Miriam , Sokolov Jonathan 
Published: June 2003

AbstractThe thermal behavior, thermal degradation kinetics, and pyrolysis of resol and novolac phenolic resins with different curing conditions, as a function of the formaldehyde/phenol (F/P) molar ratio (1.3, 1.9, and 2.5 for the resol resins and 0.5, 0.7, and 0.9 for the novolac resins) were investigated. The activation energy of the thermal reaction was studied with differential scanning calorimetry at five different heating rates (2, 5, 10, 20, and 40°C/min) between 50 and 300°C. The activation energy of the thermal decomposition was investigated with thermogravimetric analysis at five different heating rates (2, 5, 10, 20, and 40°C/min) from 30 to 800°C. The low molar ratio resins exhibited a higher activation energy than the high molar ratio resins in the curing process. This meant that less heat was needed to cure the high molar ratio resins. Therefore, the higher the molar ratio was, the lower the activation energy was of the reaction. As the thermal decomposition of the resol resins proceeded, the activation energy sharply decreased at first and then remained almost constant. The activation energy of the thermal decomposition for novolac resins with F/P = 0.5 or F/P = 0.7 was almost identical in all regions, whereas that for novolac resins with F/P = 0.9 gradually decreased as the reaction proceeded. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2589–2596, 2003
Thermotropic liquid‐crystalline copolyester/thermoplastic elastomer in situ composites. I. Rheology, morphology, and mechanical properties of extruded strands
Authors: Saikrasun S. , Bualek‐Limcharoen S. , Kohjiya S. , Urayama K. 
Published: June 2003

AbstractA thermotropic liquid‐crystalline polymer (TLCP), a copolyester with a 60/40 molar ratio of p‐hydroxy benzoic acid and poly(ethylene terephthalate), was blended with a styrene/ethylene butylene/styrene thermoplastic elastomer with a twin‐screw extruder. The rheological behavior, morphology, and mechanical properties of the extruded strands of the blends were investigated. The rheological measurements were performed on a capillary rheometer in the shear rate range of 5–2000 s−1 and on a plate‐and‐plate rheometer in the frequency range of 0.6–200 rad s−1. All the neat components and blends exhibited shear thinning behavior. Both the shear and complex viscosities of all the blends decreased with increasing TLCP contents, but the decrease in the shear viscosity was more pronounced. The best fibrillar morphology was observed in the extruded strands of a blend containing 30 wt % TLCP, and a lamellar structure started to form at 40 wt % TLCP. With an increasing concentration of TLCP, the tensile modulus of the blends was greatly enhanced, whereas the tensile strength was almost unchanged. The elongation at break of the blends first slightly decreased with the addition of TLCP and then sharply dropped at 40 wt % TLCP. The tension set measured at 200% deformation slightly increased with increasing TLCP contents up to 30 wt %, over which the set value was unacceptable for a thermoplastic elastomer. A remarkable improvement in the dynamic mechanical properties of the extruded strands was observed in the blends with increasing amounts of TLCP. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2676–2685, 2003
Biodegradation of starch and acrylic‐grafted starch by Aspergillus niger
Authors: Moreno‐Chulim M. V. , Barahona‐Perez F. , Canche‐Escamilla G. 
Published: June 2003

AbstractThe biodegradation of starch and grafted starch by Aspergillus niger was examined. The grafted polymers were poly(methyl methacrylate) (PMMA) and poly(butyl acrylate) (PBA). Thermogravimetric analysis, Fourier transform infrared, and scanning electron microscopy were used to determine the morphology and degradation degree of each material. The temperature of maximum decomposition for starch decreased as enzymatic degradation proceeded, and it was completed on the 8th day of culturing in a liquid medium. Grafted samples with PMMA and PBA achieved degradation of their starch moiety. PBA in starch‐g‐PBA samples hindered the accessibility of the enzymes to the degradable material, and this resulted in a longer degradation time. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2764–2770, 2003
Morphology, crystallinity, and electrochemical properties of in situ formed poly(ethylene oxide)/TiO2 nanocomposite polymer electrolytes
Authors: Liu Y. , Lee Jim Y. , Hong L. 
Published: June 2003

AbstractA method to produce nanocomposite polymer electrolytes consisting of poly(ethylene oxide) (PEO) as the polymer matrix, lithium tetrafluoroborate (LiBF4) as the lithium salt, and TiO2 as the inert ceramic filler is described. The ceramic filler, TiO2, was synthesized in situ by a sol–gel process. The morphology and crystallinity of the nanocomposite polymer electrolytes were examined by scanning electron microscopy and differential scanning calorimetry, respectively. The electrochemical properties of interest to battery applications, such as ionic conductivity, Li+ transference number, and stability window were investigated. The room‐temperature ionic conductivity of these polymer electrolytes was an order of magnitude higher than that of the TiO2 free sample. A high Li+ transference number of 0.51 was recorded, and the nanocomposite electrolyte was found to be electrochemically stable up to 4.5 V versus Li+/Li. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2815–2822, 2003
Mitigation of electromagnetic field radiated by PLC systems in indoor environment
Authors: Korovkin N. , Marthe E. , Rachidi F. , Selina E. 
Published: June 2003

AbstractPower line communication (PLC) is a well‐known technique for data transmission over low‐voltage power lines. The PLC signals have frequency bandwidth of about 1–30 MHz and they may cause electromagnetic interferences with services operating in the same frequency range. The regulation of electromagnetic radiation from PLC signals is currently subject of investigation in various international standardization bodies.This paper proposes a technique aiming at reducing the electromagnetic field radiated by indoor PLC signals, while not affecting the PLC signal itself. The basic idea is to take advantage of the additional ground conductor and inject a signal similar to the PLC signal into the ground–neutral line, but with a reversed phase. As a result, both the overall antenna mode‐ and transmission line mode‐currents are significantly reduced, as well as the radiated electromagnetic fields.Experimental measurements are also carried out in a building and it is shown that the proposed technique allows for a significant reduction (up to 20 dB) of the PLC electromagnetic radiation in the considered frequency range (1–30 MHz). Copyright © 2003 John Wiley & Sons, Ltd.
HomePlug 1.0 powerline communication LANs—protocol description and performance results
Authors: Lee M. K. , Newman R. E. , Latchman H. A. , Katar S. , Yonge L. 
Published: June 2003

AbstractProducts implementing the HomePlug 1.0 standard allowing high‐speed communication on low‐voltage powerlines have recently started arriving on the U.S. market for home and office networking without the requirement for installing new wires. Effective use of the powerline bandwidth requires robust physical (PHY) and medium access control (MAC) protocols to mitigate the harsh conditions of the powerline channel as well as the capability to support prioritized multimedia traffic. This paper describes powerline communications and the HomePlug 1.0 protocol, based on orthogonal frequency division multiplexing (OFDM) and carrier sense multiple access with collision avoidance (CSMA/CA), along with its changes to allow prioritized channel access. It then presents performance results for the HomePlug 1.0 protocol using a simulation model, ideal laboratory measurements with actual HomePlug 1.0 devices and field tests in a residential building. Simulation and laboratory data rates were around 6 Mbps, and field tests gave rates from 1.6 to 5.3 Mbps at the application level. Copyright © 2003 John Wiley & Sons, Ltd.
Pre‐TCR signaling regulates IL‐7 receptor α expression promoting thymocyte survival at the transition from the double‐negative to double‐positive stage
Authors: Trigueros Cesar , Hozumi Katsuto , Silva‐Santos Bruno , Bruno Ludovica , Hayday Adrian C. , Owen Michael J. , Pennington Daniel J. 
Published: June 2003

AbstractThe pre‐T cell receptor (pre‐TCR) and IL‐7 receptor (IL‐7R) are critical mediators of survival, proliferation and differentiation in immature thymocytes. Here we show that pre‐TCR signaling directly maintains IL‐7Rα expression as developing thymocytes undergo β‐selection. Inhibition of IL‐7/IL‐7R signaling in (CD44–CD25–) DN4 cells results in decreased generation of double‐positive thymocytes due to increased death of rapidly proliferating β‐selected cells. Thus, we identify a mechanism by which pre‐TCR signaling controls the selective survival of TCRβ+ thymocytes, and define a further stage of T cell differentiation in which signaling from a TCR regulates the ability of that cell to respond to cytokine.
Three‐dimensional flow structure and channel change in an asymmetrical compound meander loop, Embarras River, Illinois
Authors: Frothingham Kelly M. , Rhoads Bruce L. 
Published: June 2003

AbstractThe planform dynamics of meandering rivers produce a complex array of meander forms, including elongated meander loops. Thus far, few studies have examined in detail the flow structure within meander loops and the relation of flow structure to patterns of planform change. This field‐based investigation examines relations between three‐dimensional fluid motion and channel change within an elongated, asymmetrical meander loop containing multiple pool–riffle structures. The downstream velocity field is characterized by a high‐velocity core that shifts slightly outward as flow moves through individual lobes of the loop. For some of the measured flows this core becomes submerged below the water surface downstream of the lobe apexes. Vectors of cross‐stream/vertical velocities indicate that skew‐induced helical motion develops within the pools near lobe apexes and decays over riffles where channel curvature is less pronounced. Maximum rates of bank retreat generally occur near lobe apexes where impingement of the flow on the outer channel bank is greatest. However, maximum rates and loci of bank retreat differ for upstream and downstream lobes of the loop, leading to increasing asymmetry of loop geometry over time—a finding consistent with experimental investigations of loop evolution. Copyright © 2003 John Wiley & Sons, Ltd.
Integrin targeting using RGD‐PEI conjugates for in vitro gene transfer
Authors: Kunath Klaus , Merdan Thomas , Hegener Oliver , Häberlein Hanns , Kissel Thomas 
Published: June 2003

AbstractBackgroundTargeting to integrin receptor ανβ3 by RGD peptides seems to be a promising approach for gene delivery to proliferating endothelial cells of tumor metastases. PEGylation of cationic polymers offers a reduction of non‐specific binding to cell surfaces. However, little knowledge exists on the influence of charge shielding by PEGylation on targeted gene delivery. Therefore, a variety of RGD peptide‐polyethylenimine (PEI) conjugates with different degrees of substitution, with or without poly(ethylene glycol) (PEG) spacer, were synthesized. Influence of degree of substitution and PEG spacer on physicochemical properties as well as on integrin targeting of DNA/polymer complexes was evaluated.MethodsThe tetrapeptide RGDC was coupled to PEI with or without a PEG spacer. Complex formation with DNA was monitored by ethidium bromide (EtBr) fluorescence quenching. Hydrodynamic diameters of complexes and zeta‐potential were assessed using a Zetasizer. Fluorescence correlation spectroscopy (FCS) was used to determine peptide binding to living cells. Transfection efficiency was evaluated employing a luciferase reporter gene. Binding of complexes to Mewo cells was monitored by flow cytometry.ResultsPolyplexes of RGD‐PEI or RGD‐PEG‐PEI and DNA showed reduced quenching of EtBr fluorescence compared with PEI. All RGD conjugates formed small polyplexes (approximately 100 nm in diameter at a nitrogen/phosphate (N/P) ratio of 6.7). At N/P = 6.7, the zeta‐potentials of RGD‐PEI complexes were similar to PEI complexes (25–30 mV), while RGD‐PEG‐PEI formed neutral complexes. FCS showed saturable binding of RGD peptide to Mewo human melanoma cells and only low binding to A549 human lung carcinoma cells. A degree of substitution of 4.6% with SPDP as coupling reagent yielded a conjugate showing 50 times higher luciferase expression in Mewo cells than unmodified PEI at low N/P ratios around 3.3, while a degree of substitution of 1.6% only led to a moderately increased transfection efficiency. Flow cytometry experiments suggest that this effect is partly caused by increased attachment of complexes to cell surfaces. No improvement in transfection efficiency was found in ανβ3‐negative A549 cells. RGD‐PEG‐PEI complexes showed reasonable transfection efficiencies at high N/P ratios; however, no targeting effect could be found.ConclusionsCoupling of the tetrapeptide RGDC without a PEG spacer improved transfection efficiency of PEI in integrin‐expressing Mewo cells by 1–2 orders of magnitude, especially at low N/P ratios. The use of a PEG spacer seems to impair targeting, possibly by not only shielding PEI, but also the RGD ligand. Copyright © 2003 John Wiley & Sons, Ltd.
Treatment of Epstein‐Barr virus‐associated hemophagocytic lymphohistiocytosis (EBV‐HLH) in young adults: A report from the HLH studyl center
Authors: Imashuku Shinsaku , Kuriyama Kikuko , Sakai Rika , Nakao Yoshitaka , Masuda Shin‐ichi , Yasuda Norimasa , Kawano Fumio , Yakushijin Kimikazu , Miyagawa Akiko , Nakao Taisei , Teramura Tomoko , Tabata Yasuhiro , Morimoto Akira , Hibi Shigeyoshi 
Published: June 2003

AbstractBackgroundEpstein‐Barr virus‐associated hemophagocytic lymphohistiocytosis (EBV‐HLH), also known as EBV‐associated hemophagocytic syndrome, develops mostly in children and young adults and may be fatal. Early etoposide treatment has been confirmed to be effective in children. However, it is unclear whether the same treatment is useful in adults.ProcedureTo assess whether etoposide is effective in treating young adult cases, we retrospectively studied the therapeutic measures taken and outcomes in 20 young adult cases of EBV‐HLH. Eleven cases were registered in our HLH study center in Kyoto and nine derived from the literature. The patients were between 17 and 33 years old and eight were males. The influence of gender, cell lineage (T‐ or natural killer‐), EBV serology pattern, jaundice and treatment on the outcome was assessed.Results and ConclusionsPatients receiving etoposide within four weeks after diagnosis had a good prognosis as five of the seven patients survived compared to one of 13 not treated with etoposide or treated late (chi‐square test for survival, P = 0.0095). The Kaplan–Meier analysis showed the 2.5‐year survival of 85.7 ± 13.2% in the early etoposide‐treated patients, compared to 10.3 ± 9.4% in the remaining patients (log‐rank test, P = 0.0141). Thus, early etoposide treatment is effective in treating EBV‐HLH in young adults as well as in children. Med Pediatr Oncol 2003;41:103–109. © 2003 Wiley‐Liss, Inc.
An iterated tangential filtering decomposition
Authors: Achdou Y. , Nataf F. 
Published: June 2003

AbstractLarge linear systems arising from the discretization of partial differential equations with finite differences or finite elements on structured grids in dimensiond(d⩾ 3) require efficient preconditioners. For a symmetric and positive definite (SPD) matrix, we propose a SPD block LDLTpreconditioner whose factorized form requires a smaller amount of memory than the original matrix. Moreover, the computing time for the preconditioner solves is linear with respect to the number of unknowns. The preconditioner is built indstages: in a first stage, we use the tangential filtering decomposition of Wittumet al. and obtain a preconditioner which remains rather difficult to factorize. Then, in a second stage, we apply tangential filtering decomposition recursively to the diagonal blocks of this first preconditioner. The final stage consists of factorizing exactly the blocks corresponding to one dimensional problems. Such preconditioners can also be computed adaptively and combined in a multiplicative way. A generic programming implementation is discussed and numerical tests are presented, in particular for problems with highly heterogeneous media. Copyright © 2003 John Wiley & Sons, Ltd.
Photoluminescence from self‐assembled GaAs inclusions embedded in a GaN host crystal
Authors: Andrianov A. V. , Novikov S. V. , Li T. , Xia R. , Bull S. , Harrison I. , Larkins E. C. , Foxon C. T. 
Published: June 2003

AbstractWe report on observation of photoluminescence in 1.2–1.4 eV spectral range from As‐doped GaN layers grown by plasma‐assisted molecular beam epitaxy. We attribute this emission to recombination in GaAs inclusions formed during the growth process in the GaN(As) layers. This near‐infrared emission is efficient under UV photoexcitation, but its intensity is low for excitation energies below the band gap of GaN. Low‐temperature photoluminescence spectra reveal a set of sharp emission lines with maxima from 1.516 eV to 1.436 eV. We attribute some of these sharp lines to the emission of excitons bound to nitrogen incorporated into the GaAs crystallites and also to their GaAs‐like optical phonon replicas. Photoluminescence excitation spectra show a series of maxima, which can be attributed to the formation of bound and free excitons and also to the formation of excitons with the simultaneous emission of GaAs‐like optical phonons.
Phytoremediation of dissolved phase organic compounds: Optimal site considerations relative to field case studies
Authors: Compton Harry R. , Prince George R. , Fredericks Scott C. , Gussman Christopher D. 
Published: June 2003

AbstractThe United States Environmental Protection Agency/Environmental Response Team (EPA/ERT) has
been supporting and implementing the use of phytoremediation to remediate dissolved phase organic compounds at
Superfund sites since March 1996. Since then, ERT has applied phytoremediation field plots, both pilot and full
scale, to a variety of field conditions. These active sites vary considerably as to depth to groundwater,
groundwater transmissivity, contaminant concentrations, contaminant hydrophobicity, climate, planting design,
plant selection, planting technique, and type of monitoring. Here we compare the literature and discuss lessons
learned at five Superfund sites. Current maintenance and monitoring techniques at these sites are also discussed
with recommendations for the maintenance and monitoring of similar sites in the future. © 2003 Wiley
Periodicals, Inc.
Hydrogenosome behavior during the cell cycle in Tritrichomonas foetus
Authors: Benchimol Marlene , Engelke Flávio 
Published: June 2003

AbstractThe hydrogenosome is an unusual organelle found in several trichomonad species and other protists living in oxygen poor or anoxic environments. The hydrogenosome behavior in the protist Tritrichomonas foetus, parasite of the urogenital tract of cattle, is reported here. The hydrogenosomes were followed by light and transmission electron microscopy during the whole cell cycle. Videomicroscopy, immunofluorescence microscopy, and immunocytochemistry were also used. It is shown that the hydrogenosomes divide at any phase of the cell cycle and that the organellar division is not synchronized. During the interphase the hydrogenosomes are distributed mainly along the axostyle and costa, and at the beginning of mitosis migrate to around the nucleus. Three forms of hydrogenosome division were seen: (1) segmentation, where elongated hydrogenosomes are further separated by external membranous profiles; (2) partition, where rounded hydrogenosomes, in a bulky form, are further separated by a membranous internal septum and, (3) a new dividing form: heart‐shaped hydrogenosomes, which gradually present a membrane invagination leading to the organelle division. The hydrogenosomes divide at any phase of the cell cycle. A necklace of intramembranous particles delimiting the outer hydrogenosomal membrane in the region of organelle division was observed by freeze‐etching. Similarities between hydrogenosomes and mitochondria behavior during the cell cycle are discussed.
The effects of abutment taper, length and cement type on resistance to dislodgement of cement‐retained, implant‐supported restorations
Authors: Bernal Guillermo , Okamura Mitsunobu , Muñoz Carlos A. 
Published: June 2003

Purpose The purpose of this study was to compare the effect of 20 degrees and 30 degrees of total occlusal convergence (TOC), the occlusocervical dimension, and the type of cement on the tensile resistance to dislodgement of cement‐retained, implant‐supported restorations.Materials and Methods Cylindrical preparations with TOC angles of 20 degrees and 30 degrees and occlusocervical dimensions of 4 mm (S) and 8 mm (L) were made through a machining process. The cylinders had a shoulder finish line of 1.0 mm in depth. Eight impressions were made of each machined cylinder and poured in type IV dental stone, for a total of 32 dies. Die spacer was applied to each die. A master wax pattern was designed, and the 32 wax patterns were marginated, invested, and cast in type IV gold alloy (n= 8). The gold crowns were cemented with Fleck's cement (zinc phosphate cement), Temp‐Bond (zinc oxide eugenol cement), Temp‐Bond plus Vaseline (30% by weight), and IMProv temporary cement (acrylic/urethane cement) under a 10‐kg load and placed in a humidor at 37°C for 1 hour before testing. A uniaxial tensile force was applied to the crown using an Instron machine with a crosshead speed of 5 mm/min until cement failure occurred. Analysis of variance models were fit to determine the effect of TOC, occlusocervical dimension, and cement type of the restorations on the mean tensile strength.Results For each type of cement, the mean tensile strengths were significantly higher at 20 degrees of TOC and 8 mm of occlusocervical dimension compared with the other preparations. At this preparation, IMProv had the highest mean tensile resistance to dislodgement (47.7 ± 8.4 kg), followed by Fleck's (38.2 ± 8.8 kg), Temp‐Bond (35.9 ± 4.4 kg), and Temp‐Bond plus Vaseline (8.2 ± 2.2 kg). No statistically significant difference was observed between Temp‐Bond and Fleck's zinc phosphate cement when 20 degrees of TOC and 8 mm of occlusocervical dimension was used. There was no statistical difference in the mean tensile resistance to dislodgement for Temp‐Bond plus Vaseline with different preparation designs (p >0.05) except when 20 degrees of TOC and 8 mm of occlusocervical dimension was used. The mean tensile strength was significantly different between Temp‐Bond and Temp‐Bond plus Vaseline for each of the 4 preparation designs (p < 0.05). Among the cements tested, IMProv exhibited higher values, which were statistically different (p < 0.05). Restorations with greater occlusocervical dimension and less TOC exhibited higher tensile resistance to dislodgement.Conclusions Preparations with 20 degrees of TOC and 8 mm of occlusocervical dimension had significantly higher mean retentive values for all of the cements tested. Significant differences in mean tensile strength were observed, with the highest tensile resistance seen with IMProv, followed by Fleck's cement, and the lowest tensile resistance seen with Temp‐Bond plus Vaseline.