bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extrusion of ultrahigh molecular weight polyethylene under ultrasonic vibration field
Authors: Liu Gongde , Li Huilin 
Published: June 2003

AbstractThe effects of polypropylene (PP) and ultrasonic irradiation on the processing and mechanical properties of ultrahigh molecular weight polyethylene (UHMWPE) are studied. The results show that PP can effectively improve the fluidity and mechanical properties of UHMWPE. The Izod notched impact strength increases from 92 kJ/m2 for pure UHMWPE to 109.2 kJ/m2 for the blend of UHMWPE with 10 wt % PP. The Young's modulus increases from 528 MPa for pure UHMWPE to 1128 MPa when 25 wt % PP is contained in the blend, and the yield strength also rises when PP is added. The application of ultrasonic vibrations during extrusion can prominently decrease the die pressure and apparent viscosity of the melt, thus increasing the output of extrudate. An appropriate ultrasonic intensity and irradiation time can further promote the mechanical properties, while an overdose of irradiation destroys them. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2628–2632, 2003
Some properties of polyethylene–heptadecane mixtures
Authors: Shlyapnikov Yury A. , Kolesnikova Natalya N. 
Published: June 2003

AbstractA mixture of high‐density polyethylene and its low‐molecular‐weight analogue heptadecane was studied. The mixture behaved as a compound, that is, differently from polyethylene. Heptadecane reduced the crystallinity of polyethylene, and it intricately changed the concentration of centers sorbing phenyl‐β‐naphthylamine, the antioxidant, and simultaneously changed the equilibrium constant of sorption. Heptadecane also prolonged the duration of the antioxidant action in polyethylene. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2597–2603, 2003
Synthesis and characterization of new polyureas based on 4‐(4′‐aminophenyl)urazole and various diisocyanates
Authors: Mallakpour Shadpour , Raheno Hossein 
Published: June 2003

Abstract4‐(4′‐Aminophenyl)urazole (AmPU) was prepared from 4‐nitrobenzoic acid in six steps. The reaction of monomer AmPU with n‐isopropylisocyanate was performed in N,N‐dimethylacetamide solutions at different ratios, and the resulting disubstituted and trisubstituted urea derivatives were obtained in high yields and were finally used as models for polymerization reactions. The step‐growth polymerization reactions of AmPU with hexamethylene diisocyanate, isophorone diisocyanate, and toluene‐2,4‐diisocyanate were performed in N‐methylpyrrolidone solutions in the presence of pyridine as a catalyst. The resulting novel polyureas had inherent viscosities of 0.11–0.18 dL/g in dimethylformamide at 25°C. These polyureas were characterized with IR, 1H‐NMR, elemental analysis, and thermogravimetric analysis. Some physical properties and structural characterization of these novel polyureas are reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2692–2700, 2003
Processability, rheology, and thermal, mechanical, and morphological properties of postconsumer poly(vinyl chloride) bottles and cables
Authors: Sombatsompop N. , Sungsanit K. 
Published: June 2003

AbstractThe processability, rheology, and thermal, mechanical, and morphological properties of three different commercial poly(vinyl chloride) (PVC) compounds blended with postconsumer PVC bottles and PVC cables were examined with respect to the recycled PVC content. The addition of PVC bottle recyclates [recycled bottles (RBs)] into virgin PVC bottle (VB) and virgin PVC pipe (VP) compounds caused a progressive reduction in the average torque. No thermal degradation or color change in the RB‐blended PVC compounds used was detected through carbonyl and polyene indices from IR analysis. The rheological properties for VP compounds were more sensitive to RB addition than those of VB compounds. The extrudate swell ratio did not change with the RB content. The decomposition temperature for the VB and VP compounds increased at 60–80% RB, whereas the glass‐transition temperature was unaffected by the RB loading. The 20 and 80 wt % RB loadings were recommended for the VB and VP compounds, respectively, for the optimum impact strength, the blends showing ductile fracture with a continuous phase. At the optimum impact and tensile properties, introducing RB recyclates into the VB compounds gave better results than the VP compounds. The hardness and density of the VB and VP compounds did not change with the RB content. The RB property change was comparatively faster than that of recycled PVC pipes. Adding the PVC cable recyclate [recycled cable (RC)] to virgin PVC cable (VC) had no obvious effect on the torque value of the RC/VC blends. The decomposition temperatures of the RC/VC blends stabilized at 20–60% RC and tended to decrease at 80% RC. The ultimate tensile stress was improved by the addition of the RC compounds, whereas the hardness and density of the VC compounds were unaffected by the RC content. It was concluded that the optimum concentrations of PVC recyclates to be added to virgin PVC compounds were different from one property to another and also depended on the type of virgin PVC grade used. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2738–2748, 2003
Maximum likelihood constrained deconvolution. II: Application to experimental two‐ and three‐dimensional NMR spectra
Authors: Jeong Gwang‐Woo , Kang Heoung‐Keun 
Published: June 2003

AbstractThe maximum likelihood method (MLM) and related protocols were applied to the experimental 2‐D nuclear Overhauser effect (NOE) spectrum of a 24‐nucleotide RNA hairpin loop molecule. The output becomes more valuable when diagonal symmeterization is followed by MLM. This symmeterized maximum likelihood (SML) protocol restores the original spectral information with high fidelity by accurately partitioning components from overlapped peaks and provides substantial improvements in line shape and spectral resolution, in particular in the F1 dimension. These advantages lead to a simpler interpretation of the resonance frequencies, intensities, multiplet fine structure, and J‐coupling values from a heavily overlapped peak region. This promises a more effective tool for peak picking, assignment, and integration. Also, application of MLM and related protocols to the 2‐D NOE proton spectrum of a 24‐mer RNA dramatically increases the number of NOE‐based distance constraints that can be used for determination of its 3‐D molecular structure. By application of 3‐D MLM to a simple 3‐D spectrum, the spectral resolution and signal‐to‐noise (S/N) ratio was greatly improved by effective line sharpening and reduction of cross‐talk between planes. © 2003 Wiley Periodicals, Inc. Concepts Magn Reson 18A: 146–156, 2003
Suppressor activity of anergic T cells induced by IL‐10‐treated human dendritic cells: association with IL‐2‐ and CTLA‐4‐dependent G1 arrest of the cell cycle regulated by p27Kip1
Authors: Kubsch Sebastian , Graulich Edith , Knop Jürgen , Steinbrink Kerstin 
Published: June 2003

AbstractWe have previously shown that human IL‐10‐treated dendritic cells (DC) induce an antigen‐specific anergy in CD4+ T lymphocytes. These anergic T cells are characterized by an inhibitedproliferation, a reduced production of IL‐2, and additionally display antigen‐specific suppressor activity. In this study we investigated the mechanisms underlying the anergic state and regulatory function of these T cells. We did not observe enhanced rates of programmed cell death of anergic CD4+ suppressor T cells compared to T cells stimulated with mature DC. Cell cycle analysis by DNA staining and Western blot experiments revealed an arrest of anergic CD4+ T suppressor cells in the G1 phase. High levels of the IL‐2‐dependent cyclin‐dependent kinase (cdk) inhibitor p27Kip1 were found in anergic CD4+ suppressor T cells resulting in an inhibited activation of retinoblastoma protein and an arrest of cell cycle progression in the G1 phase. Addition of IL‐2, but not blocking of the CTLA‐4 pathway restored the proliferation of the suppressor T cells. In contrast, both treatments induced a down‐regulation of p27Kip1 and acomplete inhibition of the antigen‐specific regulatory function as demonstrated by high proliferation and enhanced IFN‐γ production of co‐cultured T cells. Further experiments demonstrated thatp27Kip‐expressing regulatory CD4+CD25+ T cells did not contribute to induction of T cell anergy in this model. Our data show that regulatory function of anergic CD4+ suppressor T cells is associated with an arrest in the G1 phase of the cell cycle mediated by increased levels of the IL‐2‐ and CTLA‐4‐dependent cdk inhibitor p27Kip1.
Essential role for IKKγ/NEMO in TCR‐induced IL‐2 expression in Jurkat T cells
Authors: He Kai‐Li , Ting Adrian T. 
Published: June 2003

AbstractThe control of IL‐2 gene expression in T cells by multiple transcriptional factors has been extensively explored, however, the role of the NF‐κB signaling pathway in TCR‐dependent IL‐2 production still remains unclear. In this study, we used a somatic cell genetics approach to address this question. Triggering TCR in mutant Jurkat T cells lacking IKKγ/NEMO failed to induce IL‐2due to a selective loss in I‐κB kinase activity, I‐κBα degradation and NF‐κB DNA‐binding activity. The AP‐1 and NF‐AT binding activities in the IL‐2 promoter were comparable between wild‐type and mutant T cells. These defects in the mutant cell line were rescued by the reintroduction of exogenous IKKγ. Taken together, our data demonstrate that IKKγ plays an essential role in TCR‐induced signaling pathways leading to IL‐2 expression.
Nucleosomes induce lymphocyte necrosis
Authors: Decker Patrice , Wolburg Hartwig , Rammensee Hans‐Georg 
Published: June 2003

AbstractNucleosomes are major autoantigens in systemic lupus erythematosus. These are found as circulating complexes in both lupus patients and lupus mice. The existence of a potential ubiquitous cellsurface receptor specific for nucleosomes has been suggested. However, neither the nature nor the role of this receptor has been identified. Moreover, the consequence of receptor‐nucleosome interaction on the target cell has not been studied in detail so far. We show here that purified nucleosomes induce cell death of normal and lupus lymphocytes ex vivo in a dose‐ and time‐dependentmanner whereas human dendritic cells were relatively resistant. Most importantly, nucleosome‐induced cell death is primary necrosis. Moreover, necrosis could be abolished when nucleosomes were first treated with deoxyribonuclease I, proteinase K or with a specific monoclonal antibody. Finally, intravenous injections of purified nucleosomes result in a reduced spleen cell number compared to buffer‐injected mice, indicating that circulating nucleosomes may behave similarly in vivo. Taken together, this is the first report indicating that nucleosomes are able to induce necrosis,which in turn could result in an amplification loop of the disease causing the inflammation observed in lupus patients.
Correction: Strong antigenic selection shaping the immunoglobulin heavy chain repertoire of B‐1a lymphocytes in λ2315 transgenic mice (Eur. J. Immunol. 7/2003)
Authors: Kretschmer K. , Engel H. , Weiss S. 
Published: June 2003

AbstractVol. 32(8) 2002, pp 2317‐2327The following information was missing in the figure legends:Figure 3: The complete sequence data from non‐Tg and L2 mice are available from GenBank under accession no. AY173963‐AY174047 and AY182378‐AY182378, respectively.Figure 5: The complete sequence data are available from GenBank under accession no. AY182489‐AY182533 (non‐Tg fetal liver), AY182599‐AY182636 (L2 FL), AY182697‐AY182717 (L2 neonatal liver, Exp. 1), AY182718‐AY182754 (L2 neonatal liver, Exp. 2), AY182555‐AY182598 (VH‐gene specific amplification from L2 day 1 liver) and AY182489‐AY182533 (non‐Tg FL).Figure 6: The sequence data from in vitro differentiated non‐Tg and Tg Pro/PreB cells are available from GenBank under accession no. AY182534‐AY182554 and AY182637‐AY182696, respectively.
In situ gene transfer into animal tendons by injection of naked DNA and electrotransfer
Authors: Jayankura Marc , Boggione Christophe , Frisén Charlotte , Boyer Olivier , Fouret Pierre , Saillant Gérard , Klatzmann David 
Published: June 2003

AbstractBackgroundDegenerative or traumatic tendon injuries are extremely common but often heal poorly, not restoring the normal function of the injured tissues. Gene transfer could improve the repair process, by permitting local production of therapeutic substances, e.g. growth factors.Methods and resultsInjection of a plasmid carrying the lacZ marker gene was performed into the Achilles tendons of rat and mouse, and the patellar tendons of rabbit. At 48 h, transduced cells were found in the injected zones of the tendons but represented a minority of the tendon cells. A kinetics study in rats permitted observation of a gradual decrease with time in the β‐gal‐expressing cell number; at day 42 no more gene expression was detected. Noteworthy, no inflammatory reaction was observed. We then investigated whether electrotransfer could improve gene transfer efficacy in rat tendon by delivering in situ electric pulses after DNA injection. Gene transfer was improved at best by ≈50% under certain electrical conditions (200 V for 10 ms or 1200 V for 100 µs). Finally, multiple injections of plasmid permitted an increase in the number of transduced cells by ≈400%.ConclusionsIn situ injection of naked DNA into tendons is a very simple technique that permits delivery of genes with a duration of expression sufficient for clinical application aimed at modulating healing or restoration of a degenerative tendon. Despite a low transfer efficiency, this method should be compatible with clinical applications aimed at delivering therapeutic substances acting at low concentration. Copyright © 2003 John Wiley & Sons, Ltd.
pARMS: a parallel version of the algebraic recursive multilevel solver
Authors: Li Zhongze , Saad Yousef , Sosonkina Masha 
Published: June 2003

AbstractA parallel version of the algebraic recursive multilevel solver (ARMS) is developed for distributed computing environments. The method adopts the general framework of distributed sparse matrices and relies on solving the resulting distributed Schur complement system. Numerical experiments are presented which compare these approaches on regularly and irregularly structured problems. Copyright © 2003 John Wiley & Sons, Ltd.
Formation mechanism of toroidal carbon nanotubes
Authors: Yang Linfeng , Jiang Jie , Dong Jinming 
Published: June 2003

AbstractIn order to study the formation mechanism of toroidal carbon nanotubes (TCNTs), we have examined their elastic energies by utilizing the continuum elastic theory. It is found that the allowed shapes of TCNTs should be determined by the constraint that the shape formation free energy should be equal to zero. We have also found that there exists a threshold condition under which a straight carbon nanotube will be curved and the TCNTs are one of the allowed shapes. The calculated torus radii for a toroidal multi‐wall carbon nanotube and single‐wall carbon nanotube bundle are in good agreement with the experimentally measured results. This indicates that the continuum elastic theory persists well into the small‐radius tubes and the formation of TCNT is a self‐organization process controlled by their shape formation free energy.
Transmission and backscattering energy distributions of slow electrons from metallic targets
Authors: Deghfel B. , Bentabet A. , Bouarissa N. 
Published: June 2003

AbstractTransmission probabilities of slow electrons normally incident on aluminum and copper thin film targets are stochastically modeled within a Monte‐Carlo framework in the examined energy range 0.5–4 keV. Attention has also been given to transmission and backscattering energy distributions. The agreement between theory and experiment is found to be good in all cases.
Some details of the electronic structure of tin oxide films
Authors: Shcherba I. D. , Zakrzewska K. , Szuber J. , Czempic G. , Senkevich A. I. , Kravchenko I. I. 
Published: June 2003

AbstractWe present experimental results of electronic structure investigations of SnO2 films by X‐ray emission spectroscopy and X‐ray photoelectron spectroscopy methods wherein X‐ray O Kα emission spectra for these materials are reported for the first time. The O 2p electron band shifts toward the upper edge of the valence band when oxygen vacancies increase, but, at the same time, the distance on the binding energy scale from the O 2p band centroid to the Fermi level remains constant. The O 2p valence electron band is broader on the higher binding energy side for oxides having more oxygen vacancies.
Phonon drag thermopower in an AlGaN/GaN heterostructure
Authors: Kubakaddi S. S. 
Published: June 2003

AbstractThe theoretical thermopower of a two‐dimensional electron gas (2DEG) is studied in a clean AlGaN/GaN heterostructure of zincblende (ZB) and wurtzite (WZ) symmetry over the temperature range 0.1–10 K. The phonon drag thermopower (Sg) due to 2DEG coupling with 3D longitudinal and transverse acoustic phonons is calculated for high‐density electrons. It is found that, in both ZB and WZ symmetries, the Sg due to piezoelectrically coupled transverse acoustic phonons is dominant over the Sg due to longitudinal acoustic phonons via piezoelectric and deformation potential coupling over the entire temperature range. This dominance is attributed to the pronounced piezoelectricity of nitrides and the smaller velocity of transverse acoustic phonons. It is shown that the total Sg ∼ Tn with n = 3.8 at temperatures T < 2.0 K and is close to n = 4 in the Bloch–Gruneisen limit. Diffusion thermopower (Sd) is also presented and is found to be significant for T below 0.4 K. The calculations are compared with the results for GaAs/GaAlAs heterostructures.
Pressure‐induced increase of exciton–LO‐phonon coupling in a ZnCdSe/ZnSe quantum well
Authors: Guo Z. Z. , Liang X. X. , Ban S. L. 
Published: June 2003

AbstractThe possibility of pressure‐induced increase of exciton–LO‐phonon coupling in ZnCdSe/ZnSe quantum wells is studied. The ground state binding energies of the heavy hole excitons are calculated using a variational method with consideration of the electron–phonon interaction and the pressure dependence of the parameters. The results show that for quantum wells with intermediate well width, the exciton binding energy and the LO‐phonon energy may coincide in the course of pressure increasing, resulting in the increase of exciton–LO‐phonon coupling. It is also found that among the pressure‐dependent parameters, the influence of the lattice constant is the most important one. The changes of both the effective masses and the dielectric constants have obvious effects on the exciton binding energy, but their influences are counterbalanced.
First principles total energy calculations of the structural and electronic properties of ScxGa1–xN
Authors: Moreno‐Armenta Maria Guadalupe , Mancera Luis , Takeuchi Noboru 
Published: June 2003

AbstractUsing first principles total energy calculations within the the full‐potential linearized augmented plane wave (FP‐LAPW) method, we have investigated the structural and electronic properties of ScxGa1–xN, with Sc concentrations varying from 0% up to 100%. In particular we have studied the relative stability of several configurations of ScxGa1–xN in wurtzite‐like structures (the ground state configuration of GaN), or in rocksalt‐like structures (the ground state configuration of ScN). It is found that for Sc concentrations less than ≈65%, the favored structure is a wurtzite‐like one, while for Sc concentrations greater than ≈65%, the favored structure is a NaCl‐like structure. It is also found that for the wurtzite‐like crystals, the fundamental gap is large and direct. For the rocksalt crystals the fundamental gap is small and indirect, but with an additional larger direct gap. In agreement with the experiments of Little and Kordesch [Appl. Phys. Lett. 78, 2891 (2001)] we found a decrease of the band gap with the increase of the Sc concentration.
Electron mobility in ZnSe single crystals
Authors: Avdonin A. N. , Nedeoglo D. D. , Nedeoglo N. D. , Sirkeli V. P. 
Published: June 2003

AbstractTemperature dependence of electron mobility in n‐ZnSe single crystals is investigated in the temperature range 77–300 K. A comparative analysis of experimental data with the known theoretical dependences calculated using solution of the Boltzmann transport equation and taking into consideration all major scattering mechanisms and screening effects is carried out. The good agreement between the experimental and theoretical dependences of electron mobility on both temperature and electron concentration is observed for the samples with various compensation ratios. It is shown that parameters such as the ionized impurity concentration and acceptor concentration can quickly be estimated for strongly compensated samples.
Environmental response to intentional dissemination of Bacillus anthracis spores in the United States–2001
Authors: Barth Edwin , Rupert Richard , Stroud Fred , Rice Eugene , Potoka Bruce 
Published: June 2003

AbstractThe intentional dissemination of Bacillus anthracis (anthrax) spores at multiple
locations in the United States in the fall of 2001 resulted not only in several deaths and illnesses
(including psychological effects), but likely changed lifestyles and attitudes, and increased the
public's awareness of individual vulnerability. While federal resources had previously been committed to
preparing local public health agencies for counter‐terrorism activities and to enhance environmental and
medical response, these release episodes have increased the consistency of environmental and medical response
activities, and increased government resources for homeland security. This article abstracts current information
from many sources that summarize the environmental responses to the anthrax releases. The article discusses the
international agreements and the U.S. regulations concerning biological weapons, the characteristics of the
anthrax organism, potential exposure pathways, adverse health conditions resulting from inhalation exposure, the
environmental response to two specific release episodes, environmental sampling and analytical procedures,
recommended personal protective equipment, and the subsequent federal efforts to improve response capabilities.
© 2003 Wiley Periodicals, Inc.