bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ab Initio Studies of ClOx Reactions: Prediction of the Rate Constants of ClO+NO for the Forward and Reverse Processes
Authors: Zhu R. S. , Lin M. C. 
Published: November 2004

AbstractThe mechanisms for ClO+NO and its reverse reactions were investigated by means of ab initio molecular orbital and statistical theory calculations. The species involved were optimized at the B3LYP/6‐311+G(3df) level, and their energies were refined at the CCSD(T)/6‐311+G(3df)//B3LYP/6‐311+G(3df) level. Five isomers and the transition states among them were located. The relative stability of these isomers is ClNO2>cis‐ClONO>trans‐ClONO>cis‐OClNO>trans‐OClNO. The heats of formation of the three most‐stable isomers were predicted using isodesmic reactions by different methods. The predicted bimolecular reaction rate constant shows that, below 100 atm, the formation of Cl+NO2 is dominant and pressure‐independent. The total rate constant can be expressed as: k(ClO+NO)=1.43×10−9 T−0.83 exp(92/T) cm3 molecule−1 s−1 in the temperature range of 200–1000 K, in close agreement with experimental data. For the reverse reaction, Cl+NO2→ClNO2 and ClONO (cis and trans isomers), the sum of the predicted rate constants for the formation of the three isomers and their relative yields also reproduce the experimental data well. The predicted total third‐order rate constants in the temperature range of 200–1000 K can be represented by: k0(He)=4.89×10−16 T−5.85 exp(−796/T) cm6 molecule−1 s−1 and k0(N2)=5.72×10−15 T−5.80 exp(−814/T) cm6 molecule−1 s−1. The predicted high‐ and low‐pressure limit decomposition rates of ClNO2 in Ar in the temperature range 400–1500 K can be expressed, respectively, by: k${{{\infty \hfill \atop d\hfill}}}$(ClNO2)=7.25×1019 T−1.89 exp(−16 875/T) s−1 and k${{{0\hfill \atop d\hfill}}}$(ClNO2)=2.51×1038 T−6.8 exp(−18 409/T) cm3 molecule−1 s−1. The value of k${{{0\hfill \atop d\hfill}}}$(ClNO2) is also in reasonable agreement with available experimental data.
Exposure of human lymphocytes and lymphoblastoid cells to simulated microgravity strongly affects energy metabolism and DNA repair
Authors: Degan Paolo , Sancandi Monica , Zunino Annalisa , Ottaggio Laura , Viaggi Silvia , Cesarone Federico , Pippia Proto , Galleri Grazia , Abbondandolo Angelo 
Published: November 2004

AbstractExposure of freshly drawn lymphocytes and lymphoblastoid cells (LB and COR3) to simulated microgravity decreased the intracellular ATP concentration to 50%–40% of the value found in normal growth conditions. The decrease was reversible although recovery to normal values occurred only slowly both in lymphocytes and in lymphoblastoid cells. Poly(ADP‐ribose) polymerase (PARP ) activity was increased indicating that cells exposed to conditions of reduced gravitation experience stress. Exposure to microgravity forces cells into a condition of metabolic quiescence in which they appear to be particularly sensitive to subsequent exposures to a genotoxic agent. Thus, treatment of cells with the strong redox agent potassium bromate under microgravity conditions, indicated an impairment in repair of DNA 8‐hydroxy‐2′‐deoxyguanosine (8‐OHdG), an oxidized derivative of deoxyguanosine. We conclude that gravitational modulation of the kind routinely obtained under laboratory conditions and during spaceflights is a stressful process to which cells appear to be extremely sensitive. These effects may reflect the physiological alterations observed in astronauts and in animals following spaceflights or exposure to conditions of simulated microgravity. © 2004 Wiley‐Liss, Inc.
β2‐glycoprotein I protects J774A.1 macrophages and human coronary artery smooth muscle cells against apoptosis
Authors: Lin Kae‐Yuan , Wang Hsueh‐Hsiao , Lai Shiau‐Ting , Pan Ju‐Pin , Chiang An‐Na 
Published: November 2004

Abstractβ2‐Glycoprotein I (β2‐GPI) is a plasma glycoprotein with multifactorial relevance to clinical consequences. It was previously indicated that β2‐GPI can selectively bind to apoptotic cells. This study was designed to determine the role of β2‐GPI in apoptosis. Using an immunohistochemical study, we observed that β2‐GPI was co‐localized with the apoptotic macrophages and smooth muscle cells (SMCs) of human coronary arteries. The contribution of β2‐GPI to apoptotic death was then investigated in vascular cells. Two nitric oxide (NO) donors, S‐nitrosoglutathione (GSNO) and S‐nitroso‐N‐acetyl penicillamine (SNAP) were used in this study to trigger apoptosis in J774A.1 macrophages and human coronary artery smooth muscle cells (HCASMC). Cell viability was significantly improved in β2‐GPI‐treated cells. It was also possible to detect a remarkable inhibitory effect by β2‐GPI on the NO‐induced apoptosis by preventing nuclear shrinkage. Furthermore, the NO‐induced apoptosis was associated with increase in caspase‐3 activity and in the protein levels of caspase‐3, c‐Fos, and c‐Jun. However, all these apoptosis‐related events were inhibited in vascular cells treated with 200 μg/ml β2‐GPI. This is the first study to show that β2‐GPI may be important in the prevention of apoptosis in vascular cells. © 2004 Wiley‐Liss, Inc.
Expression and characterization of a serine protease that preferentially cleaves insulin‐like growth factor binding protein‐5
Authors: Hou J. , Clemmons D.R. , Smeekens S. 
Published: November 2004

AbstractInsulin‐like growth factor binding proteins (IGFBPs) play important roles in regulating the functions of insulin‐like growth factors (IGFs). Because IGFBPs have very high affinity for IGF‐I and IGF‐II, they can regulate the amount of each growth factor that is able to bind to cell surface receptors, therefore, factors that alter IGFBP affinity have the capacity to regulate IGF actions. Protease activities that are present in cell culture systems and physiologic fluids have been shown to degrade IGFBP‐5. Previously, a region of sequence in a serine protease was identified that was homologous with the N‐terminal 90 amino acids of members of the IGFBP family and with members of the CCN family of proteins. In a prior study, the protease was expressed in human kidney cultured cells and the cell culture supernatants were shown to cleave IGFBP‐5, however, it is unknown whether the purified protease would cleave IGFBP‐5 and whether it would also cleave other specific forms of IGFBPs. In this study, we expressed this protease in an insect cell expression system, purified it to homogeneity and tested its capacity to cleave IGFBP‐5. The expressed protease preferentially cleaved IGFBP‐5, and it had minimal activity toward other forms of IGFBPs. The proteolytic activity of this IGFBPase is inhibited by serine protease inhibitors including PMSF and 3,4‐dichloroisocoumarin, as well as by divalent metal ions such as, Zn and Cu. Mutation of the active site serine resulted in a major reduction in IGFBP‐5 cleavage. The protease binds to heparin and its ability to degrade IGFBP‐5 is blocked in the presence of heparin. Inhibition of the activity of the protease following its secretion by B104 cells resulted in inhibition of IGFBP‐5 proteolysis and IGF‐I stimulation of protein synthesis. Northern blotting revealed that the transcript was expressed in multiple human tissues, including placenta, uterus, prostate, testis, spinal cord, brain, liver, small intestine, thyroid, and spleen. The highest expression was in uterus and placenta, suggesting a possible role of sex steroids in regulating its expression. Understanding the mechanism of how cleavage of IGFBP‐5 by this protease alters its activity will help to further our understanding of the biologic actions of the IGFs. © 2004 Wiley‐Liss, Inc.
The global fight against AIDS: how adequate are the national commissions?
Authors: Putzel James 
Published: November 2004

AbstractThis article examines the response of the international community to the HIV/AIDS crisis, focusing on efforts to promote a ‘multisectoral’ approach to fighting the epidemic. It critically assesses the evolution of an ‘organizational template’, which requires developing country governments to establish stand‐alone National AIDS Commissions in order to receive funding for HIV/AIDS programmes. While the World Bank, based on interpretations generated by the United Nations Joint Programme on HIV/AIDS (UNAIDS) and bilateral donors, claims that the model is derived from successful experience, an examination of evidence particularly from Uganda, Senegal and Malawi, suggests that National Commissions have not worked well and may, in fact, have contributed to weakening health sectors attempting to cope with the crisis. Copyright © 2004 John Wiley & Sons, Ltd.
A study on chemical estimation of pu‐erh tea quality
Authors: Liang Yuerong , Zhang Lingyun , Lu Jianliang 
Published: November 2004

AbstractChemical compositions and infusion colour differences of seven pu‐erh tea samples and their correlation to sensory quality were investigated. The results showed that the pu‐erh tea contained 37.1 mg g−1 caffeine, 15.7 mg g−1 amino acids, 67.0 mg g−1 polyphenols and 8.41 mg g−1 total catechins, on average. Among the 17 tested volatile compounds, n‐valeraldehyde was not detected. The most abundant volatile was β‐ionone and the next was linalool oxide II. Infusion colour analysis showed that the pu‐erh tea had deep hue with ΔE ranging from 66.8 to 79.2. Spearman's linear correlation analysis showed that total quality score (TQS) of the pu‐erh tea was significantly correlated to concentration of amino acids, linalool oxide II and infusion colour indicator ΔE. Five components were extracted from the 34 tested indicators by principal component analysis and were regressed on the TQS to produce six Pearson's linear regression equations for estimating sensory quality of pu‐erh tea, among which two were statistically significant, ie TQS = 57.47 − 0.18geraniol + 0.33polyphenols − 1.14n‐caproaldehyde − 1.38linalool oxide I + 0.21caffeine (p < 0.01) and TQS = 57.42‐0.03Citral + 0.33polyphenols − 1.14n − caproaldehyde − 1.40linalool oxide I + 0.20caffeine (p < 0.01). Copyright © 2004 Society of Chemical Industry
Numerical analysis of a new Eulerian–Lagrangian finite element method applied to steady‐state hot rolling processes
Authors: Synka Josef , Kainz Alexander , Maringer Robert , Obereder Andreas 
Published: November 2004

AbstractA finite element code for steady‐state hot rolling processes of rigid–visco‐plastic materials under plane–strain conditions was developed in a mixed Eulerian–Lagrangian framework. This special set up allows for a direct calculation of the local deformations occurring at the free surfaces outside the contact region between the strip and the work roll. It further simplifies the implementation of displacement boundary conditions, such as the impenetrability condition. When applied to different practical hot rolling situations, ranging from thick slab to ultra‐thin strip rolling, the velocity–displacement based model (briefly denoted as vu‐model) in this mixed Eulerian–Lagrangian reference system proves to be a robust and efficient method.The vu‐model is validated against a solely velocity‐based model (vv‐model) and against elementary methods based on the Kármán–Siebel and Orowan differential equations. The latter methods, when calibrated, are known to be in line with experimental results for homogeneous deformation cases. For a massive deformation it is further validated against the commercial finite‐element software package Abaqus/Explicit. It is shown that the results obtained with the vu‐model are in excellent agreement with the predictions of the vv‐model and that the vu‐model is even more robust than its vv‐counterpart. Throughout the study we assumed a rigid cylindrical work roll; only for the homogeneous test case, we also investigated the effect of an elastically deformable work roll within the frame of the Jortner Green's function method.The new modelling approach combines the advantages of conventional Eulerian and Lagrangian modelling concepts and can be extended to three dimensions in a straightforward manner. Copyright © 2004 John Wiley & Sons, Ltd.
Non‐linear absorption of 2,5‐dialkynyl thiophenes
Authors: Lind Per , Eriksson Anders , Lopes Cesar , Eliasson Bertil 
Published: November 2004

AbstractThree diarylalkynyl‐substituted thiophenes were synthesized and the optical power limiting (OPL) effect at 532 nm was investigated for solutions of these compounds. The relationship between the OPL and parameters obtained from molecular‐orbital‐based calculations is discussed. Semi‐empirical calculations indicate that the compounds can have a broad distribution of conformations due to inter‐ring twisting, but that the second hyperpolarizability (γ) can be significant despite a ring twist. The calculations imply that substitution by alkyl groups can lead to enhanced γ values. The measurements and calculations show a greater increase of the OPL and γ effects from compound 5 to 6 than from 6 to 7. For these compounds, which differ mainly by the length of the π‐electron system, the magnitude of non‐linear absorption seems to be well correlated with several properties of the electronic ground state estimated by standard ab initio molecular orbital calculations, as well as with γ values from the semi‐empirical calculations. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis and properties of processable conducting copolymers from N‐ethylaniline with aniline
Authors: Li Xin‐Gui , Zhou Hai‐Jun , Huang Mei‐Rong 
Published: November 2004

AbstractCopolymers were synthesized through the chemically oxidative polymerization of N‐ethylaniline (EA) and aniline (AN) in five acid aqueous media. The polymerization yield, intrinsic viscosity, molecular weight, solubility, solvatochromism, electrical conductivity, and mechanical properties of the copolymer films were systematically studied through changes in the comonomer ratio, polymerization temperature, oxidant, oxidant/monomer ratio, and acid medium. Open‐circuit‐potential and temperature measurements of the polymerization solutions showed that the polymerization rate depended on the EA content, and the polymerization was an exothermic reaction. The resultant copolymers were characterized in detail with IR, ultraviolet–visible, and 1H NMR spectroscopy, gel permeation chromatography, wide‐angle X‐ray diffractometry, and scanning electron microscopy. The reactivity ratios of the monomer pair were calculated from the 1H NMR spectra of the copolymers formed at a low conversion. The polymers exhibited good solubility and interesting solvatochromism in most of the solvents and variable conductivity with the EA/AN ratio and doping state. The conductivity of the HCl‐doped copolymers increased monotonically from 5.61 × 10−7 to 2.55 × 10−1 S/cm with decreasing EA content from 100 to 0 mol % and showed a percolation transition between EA concentrations of 20 and 30 mol %. The EA/AN copolymers also had excellent film formability and flexibility together with high mechanical and oxygen‐enriching properties. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6109–6124, 2004
Synthesis and characterization of polyaryleneetherketone triphenylphosphine oxides incorporating cycloaliphatic/cage hydrocarbon structural units
Authors: Dang Thuy D. , Dalton Matthew J. , Venkatasubramanian N. , Johnson Joel A. , Cerbus Clifford A. , Feld William A. 
Published: November 2004

AbstractNew high temperature polyaryleneetherketone triphenylphosphine oxides incorporating trans‐1,4‐cyclohexane, 1,3‐adamantane, and 4,9‐diamantane structural units were synthesized by the base‐promoted polymerization reaction between 4,4′‐difluorotriphenylphosphine oxide and the novel dihydroxy monomers trans‐1,4‐bis(4‐hydroxybenzoyl)cyclohexane, 1,3‐bis(4‐hydroxybenzoyl)adamantane, and 4,9‐bis(4‐hydroxybenzoyl)diamantane. The monomers were synthesized in a good yield by a two‐step procedure involving the Friedel–Crafts acylation of anisole by the diacid chlorides trans‐1,4‐cyclohexanedicarbonyl chloride, 1,3‐adamantanedicarbonyl chloride, and 4,9‐diamantanedicarbonyl chloride, followed by demethylation with pyridine hydrochloride. The polymers, which could be processed into tough, free standing films from organic solvents, exhibited high Tg's in the range of 192–239° as well as thermooxidative stabilities (5% weight loss in air) in the range of 445–490°. Preliminary results from a UV–visible spectroscopic study of dilute solutions of the polymers in chloroform showed absorption maxima in the 263–274 nm region and transparency to spectral radiation in the 300–800 nm range, indicating that these triphenylphosphine oxide polymers could have potential applications for space thermal control coatings. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6134–6142, 2004
Ring‐opening polymerization of L‐lactide by rare‐earth tris(4‐tert‐butylphenolate) single‐component initiators
Authors: Yu Cuiping , Zhang Lifang , Ni Xufeng , Shen Zhiquan , Tu Kehua 
Published: November 2004

AbstractThe ring‐opening polymerization of L‐lactide initiated by single‐component rare‐earth tris(4‐tert‐butylphenolate)s was conducted. The influences of the rare‐earth elements, solvents, temperature, monomer and initiator concentrations, and reaction time on the polymerization were investigated in detail. No racemization was found from 70 to 100 °C under the examined conditions. NMR and differential scanning calorimetry measurements further confirmed that the polymerization occurred without epimerization of the monomer or polymer. A kinetic study indicated that the polymerization rate was first‐order with respect to the monomer and initiator concentrations. The overall activation energy of the ring‐opening polymerization was 79.2 kJ mol−1. 1H NMR data showed that the L‐lactide monomer inserted into the growing chains with acyl–oxygen bond cleavage. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6209–6215, 2004
Effect of the γ‐form crystal on the thermal fractionation of poly(propylene‐co‐ethylene)
Authors: Wang Song , Yang Decai 
Published: November 2004

AbstractThe effect of the γ‐form crystal on the thermal fractionation of a commercial poly(propylene‐co‐ethylene) (PPE) has been studied by differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction (WAXD) techniques. Two thermal fractionation techniques, stepwise isothermal crystallization (SIC) and successive self‐nucleation and annealing (SSA), have been used to characterize the molecular heterogeneity of the PPE. The results indicate that the SSA technique possesses a stronger fractionation ability than that of the SIC technique. The heating scan of the SSA fractionated sample exhibits 12 endothermic peaks, whereas the scan of the SIC fractionated sample only shows eight melting peaks. The WAXD observations of the fractionated PPE samples prove that the content of the γ‐form crystals formed during the thermal treatment of the SIC technique is much higher than that of the SSA treatment. The former is 57.4%, whereas the later is 12.6%. The effect of theγ‐form crystals on thermal fractionation ability is discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4320–4325, 2004
Interplay between electron–phonon and electron–electron interactions
Authors: Rösch O. , Han J. E. , Gunnarsson O. , Crespi V. H. 
Published: November 2004

AbstractWe discuss the interplay between electron–electron and electron–phonon interactions for alkali‐doped fullerides and high temperature superconductors. Due to the similarity of the electron and phonon energy scales, retardation effects are small for fullerides. This raises questions about the origin of superconductivity, since retardation effects are believed to be crucial for reducing effects of the Coulomb repulsion in conventional superconductors. We demonstrate that by treating the electron–electron and electron–phonon interactions on an equal footing, superconductivity can be understood in terms of a local pairing. The Jahn–Teller character of the important phonons in fullerides plays a crucial role for this result. To describe effects of phonons in cuprates, we derive a t–J model with phonons from the three‐band model. Using exact diagonalization for small clusters, we find that the anomalous softening of the half‐breathing phonon as well as its doping dependence can be explained. By comparing the solution of the t–J model with the Hartree–Fock approximation for the three‐band model, we address results obtained in the local‐density approximation for cuprates. We find that genuine many‐body results, due to the interplay between the electron–electron and electron–phonon interactions, play an important role for the the results in the t–J model. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Forward scattering peak in the electron–phonon interaction and impurity scattering of cuprate superconductors
Authors: Kulić M. L. , Dolgov O. V. 
Published: November 2004

AbstractThe important role of the electron–phonon interaction (EPI) in explaining the normal state properties and pairing mechanism in high‐Tcsuperconductors (HTSC) is discussed. A number of experiments are analyzed such as: dynamical conductivity, Raman scattering, neutron scattering, ARPES, tunnelling measurements, and etc. They give convincing evidence that the EPI dominantly contributes to pairing in HTSC oxides. Strong electronic correlations cause the forward scattering peak (FSP) in the EPI and in the non‐magnetic impurity potential. The theory based on the FSP (whatever is its origin) explains several puzzling experimental results in ARPES and transport: (1) much smaller transport coupling constant than the pairing one (λtr≪λph); (2) the ARPES non‐shift puzzle – where the nodal kink at 70 meV is unshifted in the superconducting state while the anti‐nodal one at 40 meV is shifted; (3) d‐wave superconductivity due to the EPI; (4) robustness of d‐wave pairing in the presence of nonmagnetic impurities; (5) collapse of the elastic scattering rate near the anti‐nodal point in the superconducting state; (6) anomalous temperature dependence of the Hall angle in optimally doped HTSC. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical study of the pressure‐induced structural phase transition of ScSb and YSb
Authors: Rodríguez‐Hernández P. , Muñoz A. 
Published: November 2004

AbstractThe equations of state and phase stability of ScSb and YSb were investigated via a first‐principles theoretical calculation. For each compound we fixed the B1 (NaCl) structure as the ambient pressure phase and considered the B2 (CsCl) structure as a candidate for the high‐pressure phases. We report the results of the structural and electronic properties of these compounds in the considered structures and the theoretical transition pressure. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Cumulative coordinate technique for approximation of high atomic multipole moments of aluminophosphate sieves on the basis of electron densities calculated with DFT methods
Authors: Larin A. V. , Parbuzin V. S. , Vercauteren D. P. 
Published: November 2004

AbstractAtomic multipole moments (AMMs) for aluminophosphate sieves (ALPOs) were evaluated considering the electron density (ED) computed with the CRYSTAL98 code at various periodic Density Functional Theory (PDFT) levels as well as basis sets. Using the EDs calculated with B3LYP, Perdew‐Wang (PW91), and Perdew‐Burke‐Ernzerhof (PBE) functionals, “Mulliken” AMMs were computed within the scheme developed by Saunders et al. and approximated using a cumulative coordinate (CC) scheme similar to the one developed earlier for AMMs calculated from Hartree‐Fock EDs. The convergence of the AMMs with the basis set is discussed. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005