bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bimodal polyethylene promoted by novel nickel complex
Authors: Tang Xiubo , Cui Yong , Sun Wen‐Hua , Miao Zhenjiang , Yan Shouke 
Published: October 2004

AbstractA novel nickel complex, bis[2‐methyl‐2,4‐bis(2′‐pyridyl)‐1H‐1,5‐benzodiazepine]nickel dichloride, displayed good activity for oligomerization and polymerization of ethylene with the assistance of a co‐catalyst, methylaluminoxane (MAO). The oligomers were mainly olefins from C4 to C10, while the highly branched polyethylene (PE) had molecular weights (Mw) in the range 19 000–34 000. Bimodal distributions of the PE were clearly observed by both DSC and GPC measurements, while the spherulitic structure of the PE was shown in the morphology. Copyright © 2004 Society of Chemical Industry
Comparison of constitutive wheat bran tissues by dielectric spectroscopy and effect of their moisture content
Authors: Antoine Carole , Castellon Jerome , Toureille Alain , Rouau Xavier , Dissado Len 
Published: October 2004

AbstractThe dielectric properties of hand‐isolated wheat bran tissues (outer pericarp, intermediate and aleurone layers) were studied at 58 % and 75 % RH between 0.001 and 1E10 + 6 Hz. The measured values of the real and imaginary parts of bran tissue capacitances were modelled using an electrical circuit consisting of a constant phase angle component (CPA), a Warburg impedance and a parallel capacitance. The theoretical data from the equivalent circuit are in close agreement with the experimental values and allowed us to characterize the dielectric properties of the tissue. These results showed that the aleurone layer was the most capacitive tissue even though the outer pericarp exhibited the highest resistivity. Finally, tissue moisture contents were deduced from isotherm sorption measurements for a range of RH, and the water effect on their dielectric properties was analyzed. Copyright © 2004 Society of Chemical Industry
The effect of chemical heterogeneity on the properties of statistical copolymers: the conductivity of poly(aniline‐co‐2‐bromoaniline)
Authors: Stejskal Jaroslav 
Published: October 2004

AbstractChemical heterogeneity can influence the properties of statistical copolymers. It is shown that any integral property of a copolymer will depend on the chemical heterogeneity if such a property is a non‐linear function of copolymer composition. This is illustrated by means of the conductivity of copolymers of aniline and 2‐bromoaniline. The monomer reactivity ratios of this monomer pair are rA (aniline) = 0.94 and rB (2‐bromoaniline) = 0.31. The dependence of conductivity on the copolymer composition is non‐linear. Consequently, the conductivity depends on the compositional distribution, ie on the extent of chemical heterogeneity. Heterogeneous high‐conversion copolymers have lower conductivity than corresponding relatively homogeneous low‐conversion copolymers. The change in the average copolymer composition with increasing conversion is demonstrated for a copolymerization mixture containing 30 mol% aniline. The conductivity decreases at the same time as the chemical heterogeneity of the copolymer develops. The change in the average copolymer composition alone cannot explain the observed conductivity decrease. The conductivity is dependent not only on average composition but also on the chemical composition distribution. Copyright © 2004 Society of Chemical Industry
Space charge studies of crosslinked polyethylene midvoltage cable insulation by thermally stimulated depolarization current, infrared/Fourier transform infrared, and scanning electron microscopy
Authors: Tamayo I. , Belana J. , Diego J. A. , Cañadas J. C. , Mudarra M. , Sellarès J. 
Published: October 2004

AbstractWe studied the space charge behavior in crosslinked polyethylene cable insulation with thermally stimulated depolarization current (TSDC). The role of the semiconducting layers of the cable in space charge formation was determined with several experiments carried out with two different cables. TSDC spectra were obtained through the exchange of the semiconducting layers of each cable with aluminum or silver coatings. Heteropolar current peaks at 80 and 105 °C were observed in the TSDC spectrum. As a sample was annealed at high temperatures, the creation of traps in the material was promoted, and a homopolar contribution at 98 °C developed. This homopolar mechanism was linked to the diffusion, with annealing, of ionic components from the semiconducting layers into the insulation bulk. The penetration depth of these components was studied with Fourier transform infrared in sections obtained at several depths starting at the outer surface of the cable insulation. These diffused components remained on the crystal surfaces, and they became trapping centers for free charge. Charge injection from the semiconducting electrodes and homopolar trapping of injected charges on these components took place afterwards during polarization. This process tended to saturation. Besides this mechanism, the continuous dissociation of molecules took place in the material with thermal annealing. This ionic charge generation resulted in an increase in the heteropolar contribution of the TSDC spectrum. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4164–4174, 2004
Modeling loop reorganization free energies of acetylcholinesterase: A comparison of explicit and implicit solvent models
Authors: Olson Mark A. 
Published: October 2004

AbstractThe treatment of hydration effects in protein dynamics simulations varies in model complexity and spans the range from the computationally intensive microscopic evaluation to simple dielectric screening of charge‐charge interactions. This paper compares different solvent models applied to the problem of estimating the free‐energy difference between two loop conformations in acetylcholinesterase. Molecular dynamics (MD) simulations were used to sample potential energy surfaces of the two basins with solvent treated by means of explicit and implicit methods. Implicit solvent methods studied include the generalized Born (GB) model, atomic solvation potential (ASP), and the distance‐dependent dieletric constant. By using the linear response approximation (LRA), the explicit solvent calculations determined a free‐energy difference that is in excellent agreement with the experimental estimate, while rescoring the protein conformations with GB or the Poisson equation showed inconsistent and inferior results. While the approach of rescoring conformations from explicit water simulations with implicit solvent models is popular among many applications, it perturbs the energy landscape by changing the solvent contribution to microstates without conformational relaxation, thus leading to non‐optimal solvation free energies. Calculations applying MD with a GB solvent model produced results of comparable accuracy as observed with LRA, yet the electrostatic free‐energy terms were significantly different due to optimization on a potential energy surface favored by an implicit solvent reaction field. The simpler methods of ASP and the distance‐dependent scaling of the dielectric constant both produced considerable distortions in the protein internal free‐energy terms and are consequently unreliable. Proteins 2004. Published 2004 Wiley‐Liss, Inc.
Spin polarization and quantized conductance of ferromagnetic quantum point contacts
Authors: Li Yu‐Xian , Li Bo‐Zang 
Published: October 2004

AbstractSpin polarization and conductance quantization of three‐dimensional ferromagnetic saddle‐point contacts under the influence of the molecular fields are studied. The results indicate that the molecular fields modify the quantized conductance and spin polarization, and the change is different for spin‐up and spin‐down electrons. The larger the molecular field, the higher is the degree of the spin polarization. Quantized conductance of odd integer multiples of appears and the spin degeneracy is removed, which agrees with the experiment. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoinduced second harmonic generation of LaFe4Sb12 near spin fluctuated critical points
Authors: Nouneh K. , Viennois R. , Kityk I. V. , Terki F. , Charar S. , Benet S. , Paschen S. 
Published: October 2004

AbstractThe temperature dependence of the resistivity, the Seebeck coefficient and photoinduced second harmonic generation (PISHG) are studied near the quantum critical point in the skutterudite compound LaFe4Sb12, possessing increased spin fluctuations. We observed a large maximum of the PISHG at a temperature of about 15 K. The PISHG signal increases substantially below 35 K. We found a correlation between the temperature dependences of PISHG, resistivity and Seebeck coefficient. We proposed a phenomenological explanation for the occurrence of the PISHG signal in LaFe4Sb12 implying strong spin fluctuations exist in this system, which may present some interest for the study of other spin fluctuation systems. Physical insight into the phenomenon observed is grounded in the participation of anharmonic electron–phonon and electron–paramagnon interactions stimulated by inducing light in the interactions with the photoexcited dipole moments. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electron–phonon coupling and Jahn–Teller effect in KMgF3:Cr3+
Authors: Brik M. G. , Avram N. M. , Tanaka I. 
Published: October 2004

AbstractEnergy levels of the Cr3+ ion in the KMgF3 crystal are analyzed by means of the crystal field theory. Electron–phonon coupling constants (the Stokes shift, the force constants and the constants of the linear vibronic Hamiltonian) are evaluated using experimental spectroscopic data. The Jahn–Teller effect in the lowest excited 4T2g state of the Cr3+ ion is considered using both Ham effect and analysis of the displacements of ligands due to the combined effect of the a1g and eg normal modes of the [CrF6]3– octahedral complex. The net result of these vibrations for this cluster is an equatorial expansion by 0.070 Å and an axial compression by 0.008 Å. The value of the Jahn–Teller stabilization energy for the considered complex is about 357 cm−1. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic‐field‐induced polarization and magnetocapacitance in quantum paraelectric EuTiO3
Authors: Gong S. J. , Jiang Q. 
Published: October 2004

AbstractEuTiO3 is a quantum paraelectric as well as an antiferromagnet. The most attractive property for EuTiO3 is the magnetoelectric coupling effect. In the present work, we investigate the influence of the external fields on EuTiO3, including the electric field E and magnetic field h. The application of the electric field counteracts the quantum fluctuation and forces the system into an electrically ordered state. The applied magnetic field directly induces the fluctuation of the spin‐pair correlation and indirectly influences the dielectric behaviors through the magnetoelectric coupling. In addition, we notice that the contribution of the magnetic field depends closely on the temperature condition and the electric field background. The (p, h, E, T) and (ε, h, T) diagrams are presented showing the temperature, magnetic and electric field dependence of the polarization and the dielectric capacitance. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrospray mass spectrometry studies of macromolecules containing 1,3‐oxazolidine moieties
Authors: Maślińska‐Solich J. , Gibas E. 
Published: October 2004

AbstractThe polycondensation of terephthalaldehyde with 2‐amino‐2‐methyl‐1,3‐propanediol using acidic catalysts leads to the formation of linear polymers and macrocyclic compounds with 2‐(1′,4′‐phenylene)‐5‐methyl‐1‐aza‐3,7‐dioxabicyclo[3.3.0]octane as the repeating unit in all compounds. The structure of the polymer was determined by 1H‐ and 13C‐NMR spectroscopy, and electrospray ionization mass spectrometric (ESI‐MS) analysis. ESI‐MS measurements were used to study the details of the polymer structure and support the equimolar alternating nature of bicyclo‐O,N‐acetals of terephthaldehyde in these macromolecules. Copyright © 2004 John Wiley & Sons, Ltd.
Utility of nonaqueous capillary electrophoresis for the determination of lidocaine and its metabolites in human plasma: a comparison of ultraviolet and mass spectrometric detection
Authors: Anderson Magnus S. , Lu Bing , Abdel‐Rehim Mohamed , Blomberg Sverker , Blomberg Lars G. 
Published: October 2004

AbstractA nonaqueous capillary electrophoresis/electrospray mass spectrometry method for the separation of lidocaine (LID) and two of its metabolites, monoethylglycinexylidide (MEGX) and glycinexylidide (GX), has been developed. The separation medium was: 70 mM ammonium formate and 2.0 M formic acid in acetonitrile/methanol (60:40 v/v). With a sheath liquid of methanol/water (80:20 v/v) containing 2% formic acid and positive ion detection, reproducible determinations (8–11% relative standard deviation (RSD)) of lidocaine and its metabolites were performed in spiked human plasma. The limits of detection (LODs) were between 69.1 and 337 nM. The influences of sheath liquid composition, nebulizing gas pressure and drying gas temperature on the separation were examined. Copyright © 2004 John Wiley & Sons, Ltd.
Fragmentation characteristics of permethylated oligosaccharides using a matrix‐assisted laser desorption/ionization two‐stage time‐of‐flight (TOF/TOF) tandem mass spectrometer
Authors: Morelle Willy , Slomianny Marie‐Christine , Diemer Hélène , Schaeffer Christine , Dorsselaer Alain van , Michalski Jean‐Claude 
Published: October 2004

AbstractMatrix‐assisted laser desorption/ionization two‐stage time‐of‐flight (MALDI‐TOF/TOF) tandem mass spectrometry (MS/MS) was applied to characterize permethylated oligosaccharides. Under these ionization conditions such derivatives yield intense signals corresponding to sodium‐cationized molecular species. A systematic study was conducted on a series of neutral and sialylated permethylated oligosaccharides to allow rationalization of the fragmentation processes. The major fragments observed in the MALDI‐TOF/TOF‐MS/MS spectra result from cleavage of glycosidic bonds, preferentially at N‐acetylhexosamine and sialic acid residues. The fragments originating from both the reducing and the non‐reducing ends of the glycan yield information on sequence and branching. Cross‐ring cleavages, which are very informative of the linkages of the monosaccharide residues constituting these oligosaccharides, and ‘internal’ cleavage ions which are derived from elimination of substituents from around the pyranose ring, were also observed. This extensive fragmentation was shown to be useful for the structural characterization of oligosaccharides. MALDI‐TOF/TOF‐MS/MS of permethylated oligosaccharides appears to be a powerful tool for carbohydrate structural analysis. Copyright © 2004 John Wiley & Sons, Ltd.
Expression of PTHrP and the PTH/PTHrP receptor in growing red deer antler
Authors: Barling Peter Michael , Liu Hong , Matich Jessica , Mount Julia , Lai Ka Wai Angela , Ma Li , Nicholson Louise Frances Basford 
Published: October 2004

AbstractAntler growth is highly co‐ordinated, so that trabecular bone and antler skin (velvet) develop together, at a rapid rate and in a manner reminiscent of their development in the fetus. Parathyroid hormone‐related peptide (PTHrP) is expressed in both bone and skin, and is therefore a candidate to effect co‐ordination between these tissues. The aim of this study was to localize the expression of PTHrP and its principal receptor, the parathyroid hormone/parathyroid hormone‐related peptide receptor (PTH/PTHrPR), in antler (“spiker”) of one‐year‐old red deer. Using immunohistochemistry and in situ hybridization, intense and overlapping expression of PTHrP and its receptor was seen in developing osseocartilaginous structures and in the underlying layers of velvet epidermis. PTHrP was located on both the cell surface and within the nuclei. Our results strongly suggest that PTHrP, acting via the PTH/PTHrPR and possibly other intracrine mechanisms, plays a central role in the co‐ordinated regulation of cell division and differentiation of developing antler bone and skin.
Can opioids prevent post‐operative chronic pain?
Authors: Stubhaug Audun 
Published: October 2004

AbstractChronic post‐operative pain is a major source of suffering and disability. Better standardisation for assessing and reporting chronic post‐operative pain is needed. Peripheral and central nervous plasticity seem to play a major role in the development of chronic post‐injury pain. Complex mechanisms, including several receptor systems and messenger systems are involved. Thus, it is unlikely that one single agent will solve the problem. Opioids have proven effect both in animal models, experimental human models, and in some clinical models. Timing and dose seem to be of importance. However, it is likely that polypharmacy and multi‐modal treatment is necessary to further improve the preventive strategy.
Family disruption, economic hardship and psychological distress in schizophrenia: can they be measured?
Authors: Madianos M. , Economou M. , Dafni O. , Koukia E. , Palli A. , Rogakou E. 
Published: October 2004

AbstractThis study examined the dimensions of burden perceived by key-relatives of patients suffering from schizophrenia spectrum disorder by the development of an instrument, the Family Burden Scale (FBS) and the underlying predictors. One hundred and seventy one primary caregivers, living with 158 patients suffering from chronic psychotic illness and maintained on community basis in Athens area, were interviewed by the use of FBS supplemented by the Family Atmosphere Scale and GHQ. Construction procedure and factor analysis of FBS produced a scale of 23 items in four factors, three of them measuring objective and the fourth one, subjective burden. The scale was also proved to be reliable and valid. Forty-five percent of primary caregivers reported high levels of burden. Psychological impairment (high GHQ scores) was related with high levels of burden and negative family atmosphere. Previous admissions and duration of illness were also found to predict burden. The results suggest that FBS differentiates objective from subjective burden. Psychological well being of carers is affected by the dimensions of perceived burden.
Appraisal of caregiving, burden and psychological distress in relatives of psychiatric inpatients
Authors: Östman Margareta , Hansson Lars 
Published: October 2004

AbstractAppraisal of caregiving and its relationship to family burden and experienced mental health problems in the relatives were investigated as part of a multi-centre study of the quality of mental health services in Sweden performed in 1997. The sample was drawn from relatives of involuntarily and voluntarily admitted patients to acute psychiatric wards. The instrument used was a semi-structured questionnaire, interviewing relatives about the burden, experience of mental health problems and appraisal of the caregiving situation. The results showed a high proportion of relatives engaged in caregiving activities on a daily basis the month before the patient's admission to hospital and a high proportion of relatives appraising the caregiving activities negatively. The burden was more extensive if the relative and the patient were living together, had a longer duration of their relationship, if the relative was rendering caregiving on a daily basis and if the relative appraised caregiving negatively. The relatives' psychological distress was not related to their negative appraisal of caregiving, nor was patient characteristics, such as diagnosis and level of psychosocial functioning. The only factor found to influence the relatives' psychological distress was the duration of relationship to the patient. Interventions reducing psychological distress for relatives who have known the patients for more than 20 years, who live with the patient, who give care on a daily basis and who appraise their caregiving negatively are suggested.
Trends in the use of the Italian Mental Health Act, 1979–1997
Authors: Guaiana Giuseppe , Barbui Corrado 
Published: October 2004

AbstractItalian statistics on psychiatric bed availability, voluntary and compulsory admissions were examined from 1979 to 1997. Although the number of psychiatric beds dropped by 62.5%, the absolute number of compulsory admissions has remained substantially stable. The proportion of all admissions that were compulsory decreased from 17.1% to 11%. This study shows that a shift to community care was not associated with an increase in compulsory admissions in Italy.
Autologous preparations rich in growth factors promote proliferation and induce VEGF and HGF production by human tendon cells in culture
Authors: Anitua Eduardo , Andí Isabel , Sanchez Mikel , Azofra Juan , del Mar Zalduendo Ma , de la Fuente María , Nurden Paquita , Nurden Alan T. 
Published: October 2004

AbstractBlood platelets become activated and aggregate at the site of vessel injury. Upon activation by thrombin, platelets release storage pools of proteins and growth factors (GFs), including those involved in tissue repair. Our goal was to evaluate the potential beneficial effect of proteins released from platelet‐rich clots on tendon healing. PDGF, TGF‐β‐1, IGF‐I, HGF, VEGF and EGF were measured in human platelet‐poor plasma (PPP) and in the releasates collected from either platelet‐poor or platelet‐rich clots prepared in vitro. We then studied the effects of the releasates on human tendon cells in culture. Releasates from both platelet‐rich and platelet‐poor clots stimulated tendon cell proliferation, in contrast to un‐clotted PPP. The mitogenic activity of the supernatants was not decreased by the thrombin inhibitor, hirudin. Cultured tendon cells synthesise VEGF and HGF in the presence of PPP‐clots and PRP‐clot releasates, thus the synthesised amount was significantly higher with supernatants from platelet‐rich clots than supernatants from a platelet‐poor clot (p < 0.05). These results suggest that administering autologous platelet‐rich clots may be beneficial to the treatment of tendon injuries by inducing cell proliferation and promoting the synthesis of angiogenic factors during the healing process. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Hearing Loss in Steelband Musicians
Authors: Juman Solaiman , Karmody Collin S. , Simeon Donald 
Published: October 2004

OBJECTIVETo determine the difference in hearing between a group of steelband musicians (pannists) and a control group.DESIGN, SETTINGS, AND SUBJECTSWe conducted a controlled cross‐sectional pilot study consisting of 29 steelpan players and 30 control subjects from a steelpan orchestra (steelband) in the Otolaryngology Department of the Eric Williams Medical Sciences Complex.RESULTSSignificantly more steelpan players had a hearing loss than the control subjects at 3000 Hz, 4000 Hz, and 6000 Hz (P < 0.01). χ2 testing for trend demonstrated that the longer a steelpan player played his instrument the greater the hearing loss.CONCLUSIONThese results indicate that pannists suffer permanent auditory damage from high‐in‐tensity sound levels and that preventative measures are required to prevent this hearing loss, particularly in younger players.