bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyurethanes from renewable resources—I: Properties of polymers derived from glucose and xylose based polyols
Authors: Donnelly Michael J. , Stanford John L. , Still Richard H. 
Published: April 2007

AbstractCarbohydrates and vegetable oils are considered as replacements for some petroleum oil derived polymer precursors. For polyurethane production, blending of ethylene glycol glucoside (alkoxylated to a low level in a solution reaction) with polytetrahydrofuran diol, yields high carbohydrate content polyols of low viscosity. Characterisation allows a representative structure to be derived for these complex mixtures. From a variety of polyol blends, solid polyurethanes were prepared which ranged from linear, soluble, weak elastomers to those of increased transition temperature, stiffness, decreased solubility and lower extension under tensile load. These effects are attributable to the rigidity of the glucose unit which also increases hydrogen bonding and potential for crosslinking. Polymers prepared with the higher levels of the glucoside are able to absorb significant amounts of water suggesting uses in the biological field.
Synthesis and characterization of poly(ethylene aspartate)‐metal complexes
Authors: Bajpai U. D. N. , Rai Sandeep , Bajpai Anjali 
Published: April 2007

AbstractPoly(ethylene aspartate) [PEA] was synthesized by the melt condensation of D,L‐aspartic acid and ethylene glycol. PEA containing pendent amino and carbonyl groups in its repeating chain was used as the polymeric ligand for complexation with transition metal ions, viz. Co(II), Ni(II), Cu(II), Mn(II), Zn(II), Cd(II), Ca(II), Mg(II), Pb(II) and Hg(II). Complexation was found to be most effective in DMSO. The resulting polyester‐metal complexes were solid coloured materials which have been characterized by IR spectroscopy, elemental analysis and magnetic susceptibility measurements. The thermal stability of the polyester‐metal complexes was investigated by thermogravimetric analysis (TGA). On the basis of the physico‐chemical studies, an oxygen and nitrogen coordinated structure for the polyester‐metal complexes is proposed.
Azeotropy in terpolymerisation reactions of tributyltin acrylate or methacrylate with itaconic acid or dimethylitaconate and N‐vinyl‐2‐pyrrolidone
Authors: Azab M. M. 
Published: April 2007

AbstractTernary copolymerisations of tri‐n‐butyltin acrylate (TBTA) or tri‐n‐butyltin methacrylate (TBTMA) with itaconic acid (IA) or dimethylitaconate (DMI) and N‐vinyl‐2‐pyrrolidone (NVP) were carried out in solution at 70°C in the presence of a free radical initiator. Experimental, terpolymerisation data agreed with calculations based on the Alfrey‐Goldfinger equation. Ternary azeotropic compositions for TBTA‐IA‐NVP and TBTA‐DMI‐NVP systems were 52.60:14.80:32.60 and 56.60:26.60:16.80 mol%, respectively. Also ‘pseudoazeotropic’ regions were identified where the deviation between feed and polymer compositions is very small.
Characterisation of shrinkage in oriented PET films and containers by thermomechanical analysis (TMA)
Authors: Haworth B. , Dong Z. W. , Davidson P. 
Published: April 2007

AbstractIn this paper, we report from an extensive series of tests in which the thermal shrinkage behaviour of poly(ethylene terephthalate) (PET) homopolymer and copolymer films and containers has been studied by thermomechanical analysis (TMA). Several independent variables have been investigated, and the accuracy of dynamic TMA scans of temperature‐dependent shrinkage has been verified by parallel measurements made isothermally. Typical shrinkage levels of biaxially oriented films, of draw ratios between 2.7 and 4.1, are of the order of 5% at 100°C. The magnitude of shrinkage increases with draw ratio, and any evidence to suggest that PET copolymer is marginally more prone to shrinkage is thought to arise from differences in strain‐induced crystallinity induced by elongational deformations during processing. Correlations between measurements made on films and commercial containers are good enough to suggest that the simulation technique used is sufficiently valid for further experimentation on processing behaviour.
Microstructure and kinetics study of polymeric electrolytes precursor based on poly(ethylene oxide)/polyphosphazene blends
Authors: Herrero Consuelo R. , Acosta Jose Luis 
Published: April 2007

AbstractThis work reports on the microstructural study of the system: poly(ethylene oxide) (PEO) and a poly(fluoroalkoxyphosphazene) (PPz) and comprises both isothermal and non‐isothermal crystallization kinetics as a function of blend composition, as well as the analysis of spherulite growth, nucleating energy and nucleation density.In addition, compatibility studies were conducted based on glass transition temperature on the one hand, and on the other hand on the determination of the Flory‐Huggins interaction parameter via melting point depression.
Rubber‐modified epoxies. II. A reaction‐induced phase separation observed in‐situ and a posteriori with different methods
Authors: Chen Dong , Pascault Jean Pierre , Sautereau Henry , Vigier Gerard 
Published: April 2007

AbstractThe reaction‐induced phase separation in epoxy systems modified with rubber was firstly observed in situ with small angle X‐ray scattering (SAXS), light transmission (LT), light scattering (LS), scanning electronic microscopy and transmission electronic microscopy techniques. The different observation windows of the SAXS, LT and LS methods allow us to follow the phase separation at two size levels. The selected system was bisphenol‐A diglycidylether cured with 4,4′‐diamino‐3,3′‐dimethyldicyciohexylmethane, in the presence of 15% wt of epoxy‐terminated butadiene acrylonitrile random copolymers of different molecular weights. The phase separation inside the particles formed was followed first. Influences of precure temperature, rubber molecular weight, the postcure, vitrification and gelation on the evolution of the structure inside the particles are discussed. The real beginning of the phase separation is also discussed.
Solvolysis of methoxy‐substituted diaryliodonium tetrafluoroborates: attempted generation of a stabilized aryl cation
Authors: Fujita Morifumi , Mishima Eri , Okuyama Tadashi 
Published: April 2007

AbstractSolvolyses of monomethoxy‐ and dimethoxyphenyl(phenyl)iodonium (ArI+Ph) tetrafluoroborates were carried out in methanol and 2,2,2‐trifluoroethanol (TFE) at 130 °C. The solvolysis products include alkoxide substitution products (ArOR and PhOR) as well as iodoarenes (PhI and ArI). The ratios of ArOR/PhOR range from 8/2 to 4/6. The results are argued against formation of aryl cation. Copyright © 2007 John Wiley & Sons, Ltd.
An integrated approach to the study of the tautomerism of 4‐((Phenylimino)methyl) naphthalene‐1‐ol
Authors: Kamounah Fadhil S. , Antonov Liudmil , Petrov Vesselin , van der Zwan Gert 
Published: April 2007

AbstractThe aim of the current report is to shed light on the tautomerism of 4‐((Phenylimino)methyl) naphthalene‐1‐ol in solution, which was studied by UV–Vis spectroscopy and quantum chemical calculations. It was found that this compound does not have the typical tautomeric behavior of its analog 4‐Phenylazo‐naphthalen‐1‐ol. The complicated equilibrium between the enol‐ and keto‐like forms and two kinds of dimers that can exist in solution, is strongly dependent on the proton acceptor/donor abilities of the solvent. Using advanced data treatment quantitative information about the tautomeric and dimeric equilibrium constants was obtained. Copyright © 2007 John Wiley & Sons, Ltd.
Synthesis and electrochemical study of nitrophenyl derivatives ofβ‐cyclodextrin
Authors: Gubica Tomasz , Stroka Jadwiga , Temeriusz Andrzej 
Published: April 2007

AbstractA series of nitrophenylβ‐cyclodextrin derivatives:mono[6‐deoxy‐6‐(4‐nitrobenzamido)]‐per‐ O‐methyl‐β‐cyclodextrin (R1PhNO2),mono[6‐deoxy‐6‐(3‐nitrobenzamido)]‐per‐O‐methyl‐β‐cyclodextrin (R2PhNO2) andheptakis[6‐deoxy‐6‐(4‐nitrobenzamido)‐2,3‐di‐O‐methyl]‐β‐cyclodextrin [R3(PhNO2)7] were synthesized. Purity and composition of the obtained substances were checked. Electroreduction of nitro groups of the new synthesized compounds was investigated on mercury electrode using cyclic voltammetry and chronocoulometry. The parameters of the reduction processes of NO2groups of the investigated compounds were found not to be comparable to the reduction of nitrobenzene under the same experimental conditions. Moreover, the electroreduction of nitro groups in these nitrophenyl derivatives was dependent on pH, the type of the studied compound, and slightly on the solvent composition. All the reactants were strongly adsorbed on mercury electrode. In the case of R3(PhNO2)7, its seven nitro groups were reduced practically at the same potential, and no radical anion formation was observed. Copyright © 2007 John Wiley & Sons, Ltd.
DFT study and NBO analysis of the mutual interconversion of cumulene compounds
Authors: Nori‐Shargh Davood , Deyhimi Farzad , Boggs James E. , Jameh‐Bozorghi Saeed , Shakibazadeh Romina 
Published: April 2007

AbstractThe B3LYP/6‐31G* method was used to investigate the configurational properties of allene (1,2‐propadiene) (1), 1,2,3‐butatriene (2), 1,2,3,4‐pentateriene (3), 1,2,3,4,5‐hexapentaene (4), 1,2,3,4,5,6‐heptahexaene (5), 1,2,3,4,5,6,7‐octaheptaene (6), 1,2,3,4,5,6,7,8‐nonaoctaene (7), and 1,2,3,4,5,6,7,8,9‐decanonaene (9). The calculations at the B3LYP/6‐31G* level of theory showed that the mutual interconversion energy barrier in compounds 1–8 are: 209.73, 131.77, 120.34, 85.00, 80.91, 62.19, 55.56, and 46.83 kJ mol−1, respectively. The results showed that the difference between the average CC double bond lengths ($\bar d$) values in cumulene compounds 1 and 2, is larger than those between 7 and 8, which suggest that with large n (number of carbon atoms in cumulene chain), the $\bar d$ values approach a limiting value. Accordingly, based on the plotted data, the extrapolation to n = ∞, gives nearly the same limiting $\bar d$(i. e., $\bar d_{\lim } $). Also, NBO results revealed that the sum of π‐bond occupancies, $\bar \pi _{{\rm occupancy}} $, decrease from 1 to 8, and inversely, the sum of π‐antibonding orbital occupancies, $\bar \pi _{{\rm occupancy}}^* $, increase from compound 1 to compound 8. The decrease of $\Delta (\bar \pi _{{\rm occupancy}} - \bar \pi _{{\rm occupancy}}^* )$ values for compounds 1–8, is found to follow the same trend as the barrier heights of mutual interconversion in compounds 1–8, while the decrease of the barrier height of mutual interconversion in compounds 1–8 is found to follow the opposite trend as the increase in the number of carbon atom. Accordingly, besides the previously reported allylic resonant stabilization effect in the transition state structures, the results reveal that the $\bar d$ values, $\Delta (\bar \pi _{{\rm occupancy}} - \bar \pi _{{\rm occupancy}}^* )$, Δ(EHOMO − ELUMO), and the C atom number could be considered as significant criteria for the mutual interconversion in cumulene compounds 1–8. This work reports also useful predictive linear relationships between mutual interconversion energy barriers ($\Delta E_0^a $) in cumulene compounds and the following four parameters: ${\bar d}$, $\Delta (\bar \pi _{{\rm occupancy}} - \bar \pi _{{\rm occupancy}}^* )$, Δ(EHOMO − ELUMO), and CNumber. Copyright © 2007 John Wiley & Sons, Ltd.
Kinetics and mechanism of (salen)MnIII–catalysed hydrogen peroxide oxidation of alkyl aryl sulphides
Authors: Chellamani Arunachalam , Alhaji Nainamohamed Ismail , Rajagopal Seenivasan 
Published: April 2007

AbstractThe kinetics of (salen)MnIII complexes catalysed oxidation of aryl methyl and alkyl phenyl sulphides with hydrogen peroxide have been investigated at 25°C in 80% acetonitrile – 20% water spectrophotometrically. The reaction follows first‐order kinetics in (salen)MnIII complex and zero‐order kinetics in hydrogen peroxide. The order of the reaction with respect to sulphide is fractional and saturation in reaction rate occurs at higher sulphide concentrations. The pseudo first‐order rate constants have been analysed as per Michaelis–Menten kinetics to obtain the values of k2, the oxidant‐substrate complex decomposition rate constant, and K, the oxidant‐substrate complex formation constant. The effects of nitrogenous bases, free radical inhibitor and changes in solvent composition have also been studied. A suitable mechanism, supported by electronic‐oxidant and electronic‐substrate effect studies, involving a manganese(III)‐hydroperoxide complex as reactive species has been proposed. Copyright © 2007 John Wiley & Sons, Ltd.
Synthesis and characterization of sulfonated poly(benzoxazole ether ketone)s by direct copolymerization as novel polymers for proton‐exchange membranes
Authors: Li Jinhuan , Yu Hongyan 
Published: April 2007

AbstractA new series of sulfonated poly(benzoxazole ether ketone)s (SPAEKBO‐X) were prepared by the aromatic nucleophilic polycondensation of 4,4′‐(hexafluoroisopropylidene)‐diphenol with 2,2′‐bis[2‐(4‐fluorophenyl)benzoxazol‐6‐yl]hexafluoropropane and sodium 5,5′‐carbonylbis‐2‐fluorobenzenesulfonate in various ratios. Fourier transform infrared and 1H NMR were used to characterize the structures and sulfonic acid contents of the copolymers. The copolymers were soluble in N‐methyl‐2‐pyrrolidinone, N,N‐dimethylacetamide, and N,N‐dimethylformamide and could form tough and flexible membranes. The protonated membranes were thermally stable up to 320 °C in air. The water uptake, hydrolytic and oxidative stability, and mechanical properties were evaluated. At 30–90 °C and 95% relative humidity, the proton conductivities of the membranes increased with the sulfonic acid content and temperature and almost reached that of Nafion 112. At 90–130 °C, without external humidification, the conductivities increased with the temperature and benzoxazole content and reached above 10−2 S/cm. The SPAEKBO‐X membranes, especially those with high benzoxazole compositions, possessed a large amount of strongly bound water (>50%). The experimental results indicate that SPAEKBO‐X copolymers are promising for proton‐exchange membranes in fuel cells, and their properties might be tailored by the adjustment of the copolymer composition for low temperatures and high humidity or for high temperatures and low humidity; they are especially promising for high‐temperature applications. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2273–2286, 2007
Urodynamic changes in a noble rat model for nonbacterial prostatic inflammation
Authors: Bernoulli Jenni , Yatkin Emrah , Talvitie Eva‐Maria , Santti Risto , Streng Tomi 
Published: April 2007

AbstractBACKGROUNDChronic nonbacterial prostatitis (CP) associated with voiding dysfunction is a poorly understood clinical phenomenon. The goal of the present study was to induce prostatic inflammation with estrogen and androgen treatment and to record associated urodynamic changes in Noble rats.METHODSRats were treated with estradiol and testosterone implants to increase estradiol concentration in serum while testosterone concentration was maintained at or slightly above the control level. The urodynamical recordings were performed under anesthesia after the hormone treatments for 3 and 6 weeks. The dorsolateral lobes of the prostates were removed for histopathological analysis after recordings.RESULTSAfter the 3‐week treatment, lymphocytes, mainly T‐cells, were located around the capillaries. During the following 3 weeks lymphocytes migrated into stroma and acini. Cytotoxic T‐cells were seen intraepithelially, and neutrophiles inside the acini. Removal of estrogen implant or treatment with anti‐estrogen diminished inflammation. No changes in voiding pattern were seen after the 3‐week treatment. Three weeks later, bladder weight and capacity were increased, and the micturition time was prolonged.CONCLUSIONSElevated estrogen concentration was essential for the gradual development of prostatic inflammation. The profile and location of inflammatory cells suggest that prostatic vasculature is one of the sites of estrogen action. Urodynamic changes which developed in association with glandular inflammation indicated abnormal bladder function, reflecting an incipient obstruction. Prostate 67: 888–899, 2007. © 2007 Wiley‐Liss, Inc.
Lithium suppresses cell proliferation by interrupting E2F–DNA interaction and subsequently reducing S–phase gene expression in prostate cancer
Authors: Sun Aijing , Shanmugam Ilanchezian , Song Jiawu , Terranova Paul F. , Thrasher J. Brantley , Li Benyi 
Published: April 2007

AbstractBACKGROUNDLithium is an existing drug for bipolar disorder and its uptake was recently linked to reduced tumor incidence compared to the general population. The major target of lithium action is glycogen synthase kinase 3 (GSK‐3). Since GSK‐3 expression and activation are associated with prostate cancer progression, the anti‐cancer potential of lithium on prostate cancer was investigated in this study.METHODSMultiple prostate cancer cell lines were treated with lithium chloride (LiCl). Cell proliferation and cell cycle distribution were analysed. DNA replication was determined using BrdU labeling assay. Genome‐wide screening of gene expression was performed using cDNA microarray assay. GSK‐3β gene‐specific silencing was conducted using small interferencing RNA (siRNA) transfection. E2 factor (E2F) transactivation was evaluated using reporter gene assay and E2F–DNA interaction was determined with chromatin‐immunoprecipitation assay (ChIP).RESULTSLiCl significantly inhibited cell proliferation, which was associated with reduced DNA replication and S‐phase cell cycle arrest. LiCl significantly decreased the expression of multiple DNA replication‐related genes, including cell division cycle 6 (cdc6), cyclin A, cyclin E, and cdc25C, which are regulated by E2F factor during cell cycle. A novel GSK‐3‐specific inhibitor TDZD‐8 and GSK‐3β siRNA also suppressed the expression of these E2F target genes, indicating that LiCl‐induced anti‐cancer effect was associated with GSK‐3β inhibition. Furthermore, LiCl suppressed E2F transactivation by interrupting the interaction of E2F1 factor with its target gene promoter.CONCLUSIONSThese data indicated that LiCl suppresses cancer cell proliferation by disrupting E2F–DNA interaction and subsequent E2F‐mediated gene expression in prostate cancer. Prostate 67: 976–988, 2007. © 2007 Wiley‐Liss, Inc.
Isolation and characterization of antimicrobial proteins and peptide from chicken liver
Authors: Li Guan‐Hong , Mine Yoshinori , Hincke Maxwell T. , Nys Yves 
Published: April 2007

AbstractEndogenous antimicrobial peptides and proteins are crucial components of the innate immune system and play an essential role in the defense against infection. Antimicrobial activity was detected in the acid extract of livers harvested from healthy adult White Leghorn hens, Gallus gallus. Two antimicrobial proteins and one antimicrobial polypeptide were isolated from the liver extract by cation‐exchange and gel filtration chromatography, followed by two‐step reverse‐phase high‐performance liquid chromatography (RP‐HPLC). These antimicrobial components were identified as histones H2A and H2B.V, and histone H2B C‐terminal fragment using peptide mass fingerprinting and partial sequencing by tandem nanoelectrospray mass spectrometry. The proteins and the peptide identified in the present study, which exhibited antimicrobial activity against both Gram‐positive and Gram‐negative bacteria, were thermostable and showed salt‐resistant activity. The antimicrobial properties of histones and histone fragment in chicken provide further evidence that histones, in addition to their role in nucleosome formation, may play an important role in innate host defense against intracellular or extracellular microbe invasion in a wide range of animal species. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Current‐induced switching in spin‐valve structures
Authors: Barnaś J. , Gmitra M. , Misiorny M. , Dugaev V. 
Published: April 2007

AbstractSpin transfer between conduction electrons and local magnetic moments can switch spin valves between different magnetic configurations. In some conditions, however, the spin torque can induce magnetic switching to stationary precessional modes. In this paper we consider current‐induced magnetic switching in nanopillar spin valves including two thin magnetic films separated by a nonmagnetic layer, and in molecular‐based spin valves. In the former case the spin torque is calculated from the macroscopic spin diffusion equations, while in the latter one we use quantum description based on the Fermi golden rule. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Semiconductor nanocrystals and embedded quantum dots: Electronic and optical properties
Authors: Schulz S. , Schumacher S. , Czycholl G. 
Published: April 2007

AbstractA tight‐binding model for semiconductor quantum dots (QD) consisting of a small gap semiconductor material A embedded within a larger gap material B is used to determine the bound, localized one‐particle QD‐states. The form and symmetry properties of these states and their dependence on form, size and composition of the QDs are discussed. The Coulomb and dipole matrix elements between these states are calculated so that a many‐body Hamiltonian is derived describing the elctronic properties of the QDs and the coupling to an applied (optical) electric field. Truncating the many‐particle Hilbert space by taking into account only a finite number of localized electron and hole states the many‐body Hamiltonian can be solved exactly. The resulting excitation spectrum and optical properties are presented and discussed. The method is, in particular, applied to CdSe QDs embedded in ZnSe with zincblende structure, to CdSe nanocrystals, and to InN QDs embedded in GaN with wurtzite structure. For the latter case also the influence of an intrinsic piezoelectric field and of the special symmetry properties of the wurtzite structure are discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrospray ionization/atmospheric pressure photoionization multimode source for low‐flow liquid chromatography/mass spectrometric analysis
Authors: Short Luke C. , Hanold Karl A. , Cai Sheng‐Suan , Syage Jack A. 
Published: April 2007

AbstractAnalysis of several polar and non‐polar compounds is performed with a newly developed dual electrospray ionization/atmospheric pressure photoionization (ESI/APPI) or ESPI source. Several variables are considered in the source, such as ESI probe heater temperature, solvent flow, dopant effects, repeller plate voltage, source geometry and photon energy (Kr vs. Ar lamp). Direct photoionization resulting in a molecular radical cation [M].+ dominates at high temperatures (>400°C) and low flow rates (<200 µL/min). Indirect photo‐induced chemical ionization (PCI) involving solvent molecules becomes important at lower temperatures and higher solvent flow rates. Indirect PCI is enhanced using an Ar lamp, which yields comparable [M+H]+ signal but poorer [M].+ signal than the Kr lamp at lower temperatures and higher flow rates. This is in support of our recent finding that the Ar lamp results in a solvent‐dependent enhancement of analyte molecules via PCI. Analysis of 12 compounds in methanol under low‐flow conditions (10 µL/min) demonstrates that the dual ESPI source performs favorably for most compounds versus the standard ESCI source, and significantly better than ESCI for the analysis of unstable drugs, like flurbiprofen. Several factors contributing to the benefits of the ESPI source are the shared optimal geometry for ESI and APPI sources and soft ionization of APPI versus APCI. Copyright © 2007 John Wiley & Sons, Ltd.