bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conducting polymers grown in hydrogel scaffolds coated on neural prosthetic devices
Authors: Kim Dong‐Hwan , Abidian Mohammad , Martin David C. 
Published: November 2004

AbstractThe conducting polymer polypyrrole (PPy) was electrochemically grown on hydrogel scaffolds deposited on the surface of microfabricated neural prosthetic devices. It is shown that the pyrrole monomer can be grown vertically through the hydrogel layer up to the surface without affecting the adjacent sites on the probes. The electrochemical properties of the conducting polymer‐modified hydrogels were studied by impedance spectroscopy and cyclic voltammetry. It is also found that the conducting polymers could still be readily grown through the hydrogel after the microstructure is disrupted by freeze drying. Impedance measurements at the biologically important frequency of 1 kHz showed that the minimum impedance of this polymer‐modified hydrogel was 7 kΩ. This is much lower than the minimum impedance of polypyrrole film (∼100 kΩ). © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 577–585, 2004
Formation of hydroxyapatite/biopolymer biomaterials. I. Microporous composites from solidified emulsions
Authors: Ritzoulis C. , Scoutaris N. , Demetriou E. , Papademetriou K. , Kokkou S. , Stavroulias S. , Panayiotou C. 
Published: November 2004

AbstractMicroporous materials of controlled pore size were prepared by means of a three‐step process involving in situ hydrochemical preparation of a hydroxyapatite–sodium caseinate (HAp–Cas) composite material into a Cas‐stabilized oil‐in‐water emulsion, subsequent concentration and drying of the composite–emulsion, and removal of the oil by means of supercritical carbon dioxide extraction. The resulting composite materials were found to contain micron‐sized pores in the space previously occupied by the oil droplets. In order to elucidate the structure of the resulting porous product, its Cas–HAp composition was studied in the corresponding nonporous composite material. In nonporous samples, a protein assay by means of visible spectroscopy suggested equilibrium between the Cas that was trapped in the composite structure and the Cas that remained in solution after precipitation. This observation was confirmed by separate thermogravimetric analysis and Fourier transform IR spectroscopy measurements. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 675–684, 2004
Lysosomal and mitochondrial pathways in H2O2‐induced apoptosis of alveolar type II cells
Authors: Yin Lei , Stearns Rebecca , González‐Flecha Beatriz 
Published: November 2004

AbstractIncreasing evidence suggests a role for apoptosis in the maintenance of the alveolar epithelium under normal and pathological conditions. However, the signaling pathways modulating alveolar type II (AT II) cell apoptosis remain poorly defined. Here we investigated the role of lysosomes as modulators of oxidant‐mediated AT II cell apoptosis using an in vitro model of H2O2‐stress. H2O2 stress led to time‐dependent increases in intracellular oxidants, mitochondrial membrane polarization, cytochrome c release, lysosomal rupture, and AT II cells apoptosis. Increased apoptosis was prevented by specific inhibition of the caspase cascade using the broad‐spectrum caspase inhibitor z‐VAD‐fmk or a caspase 3 inhibitor, or by using functional inhibitors for cathepsin D (pepstatin A) or cathepsin B. Inhibition of cathepsin D also prevented mitochondrial permeabilization and cythocrome c release suggesting that lysosomal rupture precedes and is necessary for the activation of the mitochondrial pathway of cell death. © 2004 Wiley‐Liss, Inc.
Quintessential PBDs and PBDs with prime power block sizes ≥ 8
Authors: Abel R. J. R. , Bennett F. E. 
Published: November 2004

AbstractIn this paper, we look at the existence of (v K) pairwise balanced designs (PBDs) for a few sets K of prime powers ≥ 8 and also for a number of subsets K of {5, 6, 7, 8, 9}, which contain {5}. For K = {5, 7}, {5, 8}, {5, 7, 9}, we reduce the largest v for which a (v, K)‐PBD is unknown to 639, 812, and 179, respectively. When K is Q≥8, the set of all prime powers ≥ 8, we find several new designs for 1,180 ≤ v ≤ 1,270, and reduce the largest unsolved case to 1,802. For K =Q0,1,5(8), the set of prime powers ≥ 8 and ≡ 0, 1, or 5 (mod 8) we reduce the largest unknown case from 8,108 to 2,612. We also obtain slight improvements when K is one of {8, 9} or Q0,1(8), the set of prime powers ≡ 0 or 1 (mod 8). © 2004 Wiley Periodicals, Inc.
Fair trade coffee: building producer capacity via global networks
Authors: Raynolds Laura T. , Murray Douglas , Leigh Taylor Peter 
Published: November 2004

AbstractThis article examines the ongoing rapid expansion in Fair Trade coffee networks linking Northern consumers with producers in the global South. We provide a comparative analysis of the experiences of seven coffee producer co‐operatives in Latin America, identifying the characteristics which facilitate successful integration into Fair Trade networks. Our analysis finds that coffee organizations, communities and producers derive important material and non‐material benefits from Fair Trade. We conclude that while the financial benefits of Fair Trade appear the most important in the short run, it is the capacity building nature of Fair Trade that will prove the most important in fueling sustainable development in the long run. Copyright © 2004 John Wiley & Sons, Ltd.
Mass spectrometric analysis of 7‐sulfoxymethyl‐12‐methylbenz[a]anthracene and related electrophilic polycyclic aromatic hydrocarbon metabolites
Authors: Lehner Andreas F. , Horn Jamie , Flesher James W. 
Published: November 2004

AbstractThe Meso‐region theory of polycyclic aromatic hydrocarbon (PAH) carcinogenesis predicts that the development of pronounced carcinogenicity depends on the introduction of a good leaving group on alkyl side‐chains attached to the exceptionally reactive meso‐anthracenic or L‐region positions of PAHs. Thus, the first step in carcinogenesis by methylated PAHs such as 7,12‐dimethylbenz[a]anthracene (DMBA) would be the hydroxylation of the L‐region methyl groups, particularly the 7‐methyl group. The second would be the formation of a metabolite, e.g. a sulfate ester, which is expected to be a good leaving group capable of generating a highly reactive benzylic carbocation. 7‐Hydroxymethyl‐12‐methylbenz[a]anthracene (7‐HMBA) is a metabolite of DMBA, and sulfation of 7‐HMBA to a 7‐sulfoxymethyl metabolite (7‐SMBA) is a known Phase II metabolic process designed to facilitate excretion, but actually enabling more destructive side‐reactions. These side‐reactions occur with generation of an electrophilic 7‐methylene carbonium ion, and/or by in vivo halide exchange to provide neutral side‐products more capable of entering cells, especially those of DMBA target tissues. Electrospray ionization mass spectrometry (MS) enabled us to visualize 7‐SMBA as an intact m/z 351 conjugate anion by negative mode, and as a released m/z 255 carbonium ion by positive mode. Upon prolonged refrigeration, 7‐SMBA accumulated an m/z 383 photooxide, which appeared capable of re‐evolving the starting material as visualized by tandem quadrupole MS, or MS/MS. The 7‐SMBA carbonium ion provided interpretable fragments when studied by fragment ion MS/MS, including those representing the loss of up to several protons. Subtle differences in this property were encountered upon perturbing 7‐SMBA, either by warming it at 37 °C for 2 h or by substituting the initial sulfoxy group with an iodo group. Side‐reactions accounting for such proton losses are proposed, and are of interest whether they occur in the mass spectrometer, in solution or both; these proposals include acidity at the 12‐methyl position and cyclization between the 12‐methyl group and the adjacent C‐1 position. It is also suggested that such side‐reactions may comprise one route to relieving steric strain arising between the 12‐methyl group and the angular benzo ring of 7‐SMBA. Copyright © 2004 John Wiley & Sons, Ltd.
Parametrices of mixed elliptic problems
Authors: Harutjunjan G. , Schulze B.‐W. 
Published: November 2004

AbstractMixed elliptic problems for differential operatorsAin a domain Ω with smooth boundaryYare studied in theformwhereY±⊂Yare manifolds with a common boundaryZ, such thatY–∪Y+=YandY–∩Y+=Z, with boundary conditionsT±onY±(with smooth coefficients up toZfrom the respective side) satisfying the Shapiro–Lopatinskij condition. We consider such problems in standard Sobolev spaces and characterise natural extra conditions on the interfaceZwith an analogue of Shapiro–Lopatinskij ellipticity for an associated transmission problem on the boundary; then the extended operator is Fredholm. The transmission operators on the boundary with respect toZbelong to a complete pseudo‐differential calculus, a modification of the algebra of boundary value problems without the transmission property. We construct parametrices of elliptic elements in that calculus, and we obtain parametrices of the original mixed problems under additional conditions on the interface. We consider the Zaremba problem and other mixed problems for the Laplace operator, determine the number of extra conditions and calculate the index of associated Fredholm operators. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Chiral recognition by mass‐resolved laser spectroscopy
Authors: Speranza Maurizio , Satta Mauro , Piccirillo Susanna , Rondino Flaminia , Paladini Alessandra , Giardini Anna , Filippi Antonello , Catone Daniele 
Published: November 2004

AbstractChiral recognition is a fundamental phenomenon in life sciences, based on the enantioselective complexation of a chiral molecule with a chiral selector. The diastereomeric aggregates, formed by complexation, are held together by a different combination of intermolecular forces and are therefore endowed with different stability and reactivity. Determination of these forces, which are normally affected in the condensed phase by solvent and supramolecular interactions, requires the generation of the diastereomeric complexes in the isolated state and their spectroscopic investigation. This review deals with chiral recognition in the gas phase through the application of laser‐resolved mass spectrometric techniques (R2PI‐TOF and RET‐MS). The measurement of the fragmentation thresholds of diastereomeric clusters by these techniques allows the determination of the nature of the intrinsic interactions, which control their formation and affect their stability and reactivity. © 2004 Wiley Periodicals, Inc., Mass Spec Rev 24:588–610, 2005
Fluorimetric detection of cyclodextrins via complexation with fluorescence probe in microcolumn liquid chromatography
Authors: Takeuchi Toyohide , Kitamaki Yuko , Miwa Tomoo 
Published: November 2004

AbstractCyclodextrins (CDs) are visualized by fluorimetric detection based on inclusion complexation with fluorescence probes in microcolumn liquid chromatography. Visualization of CDs is attributed to the fact that the fluorescence intensity of 2‐p‐toluidinylnaphthalene‐6‐sulfonate or other fluorescence probes increases when it is incorporated into the cavity of CDs. The present detection method can be applied to the determination of CDs contained in horseradish paste. © 2001 John Wiley & Sons, Inc. J Micro Sep 13: 19–23, 2001
Behavior problems in young children: An analysis of cross‐informant agreements and disagreements
Authors: Gross Deborah , Fogg Louis , Garvey Christine , Julion Wrenetha 
Published: November 2004

AbstractThis study examined (a) convergence between parents' and day care teachers' ratings of children's behavior problems, and (b) whether agreements and disagreements were associated with characteristics of the informant, context, or measures. Parents of 241, 2–4‐year old children in day care centers serving low‐income families completed measures of child behavior problems, parenting style, stress, depression, and self‐efficacy. Teachers completed a measure of classroom behavior problems. There was a low correlation between parents' and teachers' ratings of child behavior (r = .17), and few children (2.5%) received high behavior problem scores from both parents and teachers. Cross‐informant agreement on high behavior problem children was related to characteristics of the informants and home context. Implications for identifying children at risk are discussed. © 2004 Wiley Periodicals, Inc. Res Nurs Health 27:413–425, 2004
Physical activity, self‐efficacy, and perceived exertion among adolescents
Authors: Robbins Lorraine B. , Pender Nola J. , Ronis David L. , Kazanis Anamaria S. , Pis Monika B. 
Published: November 2004

AbstractThe relationship of self‐efficacy, a sense of confidence in personal physical activity (PA) skills, to perceived exertion during activity was explored among 168 African American and European American boys and girls between 9 and 17 years of age. Participants walked/ran on a treadmill at a speed equivalent to 60% of their peak VO2 for 20 minutes and provided ratings of exertion every 4 minutes. Pre‐activity self‐efficacy predicted perceived exertion for boys only. Girls were lower than boys in pre‐activity self‐efficacy and subsequently reported greater perceived exertion. For both genders, lower perceived exertion during PA resulted in higher post‐activity self‐efficacy. Uncomfortable perceptions of exertion during initial efforts to increase PA are likely to discourage future activity. Interventions that can lower perceptions of exertion may enhance self‐efficacy and promote a sense of competence in PA skills. © 2004 Wiley Periodicals, Inc. Res Nurs Health 27:435–446, 2004
Poly(ether imide)s derived from phthalazinone‐containing dianhydrides
Authors: Wang Jin Yan , Liao Gong Xiong , Liu Cheng , Jian Xi Gao 
Published: November 2004

AbstractAn unsymmetrical and noncoplanar heterocyclic dianhydride was synthesized from a bisphenol‐like phthalazinone, 4‐(4‐hydroxylphenyl)‐2,3‐phthalazin‐1‐one, and a series of novel poly(ether imide)s based on it, with intrinsic viscosities of 0.67–1.42 dL/g, were obtained by one‐step solution polymerization in m‐cresol at 200 °C for 20 h. The polymers were readily soluble in N‐methyl‐2‐pyrrolidinone and m‐cresol. The poly(ether imide)s derived from 4,4′‐oxydianiline and 4,4′‐methylenedianiline were also very soluble in chloroform, 1,1′,2,2′‐tetrachloroethane, and N,N‐dimethylacetamide. The glass‐transition temperatures were 289–326 °C, as determined by differential scanning calorimetry. All the degradation temperatures for 5% weight loss occurred above 482 °C in nitrogen. The tensile strength of thin films of some of the polymers varied from 103.1 to 121.4 MPa. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6089–6097, 2004
Preparation and characterization of core–shell polymer particles with protonizable shells prepared by oxyanionic polymerization
Authors: Jin Lan , Deng Yonghui , Hu Jianhua , Wang Changchun 
Published: November 2004

AbstractA series of polystyrene (PS)/poly(vinyl acetate) (PVAc) crosslinked particles (240, 210, or 90 nm) with different concentrations of PS (75, 50, or 25 wt %) were prepared by soap‐free emulsion polymerization. Based on the crosslinked polymer particles, three series of monodisperse core–shell particles with pH‐sensitive poly[2‐(dimethylamino)ethyl methacrylate] (PDMAEMA) shells were synthesized by oxyanionic polymerization. During the oxyanionic polymerization, the acetate groups of PVAc were hydrolyzed, and the hydroxyl groups that formed on the surfaces of the particles, acting as initiators, were transferred to O−K+ by DMSO−K+ (where DMSO is dimethyl sulfoxide) at the same time; then, O−K+ initiated the polymerization of 2‐(dimethylamino)ethyl methacrylate. 1H NMR and Fourier transform infrared studies confirmed the existence of PDMAEMA shells, and the contents of PDMAEMA were measured by elemental analysis. Because the PDMAEMA chain could be protonated at a low pH, these core–shell particles could adsorb negatively charged modified magnetite particles, and at higher pHs, the magnetite particles could be released again; this process was reversible. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6081–6088, 2004
Effects of DL‐methionine on hatching and activity of Meloidogyne incognita eggs and juveniles
Authors: Talavera Miguel , Mizukubo Takayuki 
Published: November 2004

AbstractSeveral concentrations of DL‐methionine were tested in the laboratory for their effects on Meloidogyne incognita (Kofoid & White) Chitwood egg hatching and juvenile activity in aqueous suspensions and infested soil. After 7 days in methionine solutions, the proportions of hatched eggs were reduced by 23.3% at 0.25 mg litre−1 methionine and by 76.4% at 25 g litre−1 when compared with controls in tap water. An effect of methionine solutions on juvenile activity was also apparent after 24 h in the 25 g litre−1 treatment, where the percentage of active M incognita juveniles was reduced by 16.3%. Further reductions in nematode mobility were observed as the time of exposure increased, and at lower methionine concentrations over longer exposure times. When methionine solutions were applied to soil infested with M incognita, reductions in egg hatching and juvenile activity were observed at 0.1 and 1 mg methionine g−1 soil in both sand and clay–loam soils. The percentage of hatched eggs one week after methionine application at rates of 1 mg g−1 was lower in sand (5.6%) and clay–loam soil (20.8%) than in controls where egg hatch was 52.0% and 48.0% in sand and soil, respectively. Non‐active juveniles were found at 1 mg methionine g−1 soil one week after its application to soil. Copyright © 2004 Society of Chemical Industry
Superconductive excitations and the infrared vibronic spectra of BSCCO
Authors: Phillips J. C. 
Published: November 2004

AbstractThe oxygen dopant concentration dependence of the “quasiparticle” feature at 600–750 cm–1 of the infrared spectrum of Bi2Sr2CaCu2O8+δ (BSCCO), lying near but above the top of the host phonon spectrum at 600 cm–1, is strongly correlated with superconductivity. Using parameter‐free topological methods, theory assigns this feature to split apical oxygen interstitials. It explains both the qualitative similarities and the quantitative differences between “quasiparticle” features identified in infrared and photoemission data, as well as identifying new features in the infrared spectra. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phonons, electronic charge response and electron–phonon interaction in the high‐temperature superconductors
Authors: Falter Claus 
Published: November 2004

AbstractWe investigate the complete phonon dispersion, the phonon induced electronic charge response and the corresponding self‐consistent change of the crystal potential an electron feels as a direct measure of the electron–phonon interaction in the high‐temperature superconductors within a microscopic model in the framework of linear response theory. Moreover, dielectric and infrared properties are calculated. The experimentally observed strong renormalization of the in‐plane oxygen bond‐stretching modes which appears upon doping in the high‐temperature superconductors is discussed. It is shown that the characteristic softening, indicating a strong nonlocal electron–phonon interaction, is most likely a generic effect of the CuO plane and is driven by a nonlocal coupling of the displaced ions to the localized charge‐fluctuations at the Cu and the Oxy ions. At hand of the oxygen bond‐stretching modes it is illustrated how lattice‐, charge‐ and spin‐degrees of freedom may act synergetically for anisotropic pairing in the high‐temperature superconductors. The different behaviour of these modes during the insulator‐metal transition via the underdoped phase is calculated and from a comparison of these generic modes in the different phases conclusions about the electronic state are drawn. For the non‐cuprate potassium doped high‐temperature superconductor Ba–Bi–O also a very strong and anisotropic renormalization of the oxygen bond‐stretching modes is predicted. In another investigation c‐axis polarized infrared‐ and Raman‐active modes of the HTSC's are calculated in terms of charge fluctuations and anisotropic dipole‐fluctuations. Mode assignments discussed controversially in the literature are proposed. Finally, interlayer phonons propagating along the c‐axis and their accompanying charge response are investigated. Depending on the strength of the interlayer coupling calculations are performed ranging from the static, adiabatic response regime to the non‐adiabatic regime where dynamical screening of the bare Coulomb interaction and phonon–plasmon coupling becomes relevant within a certain region around the direction of the c‐axis. A comparison with the experimental situation is given. Both, the oxygen bond‐stretching modes calculated in adiabatic approximation and the non‐adiabatic coupled c‐axis phonon–plasmon modes are found to be important for pairing via lattice‐ and charge‐degrees of freedom. Favouring aspects to achieve high‐temperature superconductivity are also discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical examination of substituent effects on the stabilization of a SnY (Y = Sb and Bi) multiple bond
Authors: Hu Ya‐Hui , Su Ming‐Der 
Published: November 2004

AbstractThe potential energy surface for the unimolecular rearrangement XSnY → TS → SnYX (Y = Sb, Bi) was investigated using the B3LYP and QCISD methods. To explore electronic effects on the relative stability of XSnY and SnYX, the first‐row substituents (X = H, Li, BeH, BH2, CH3, NH2, OH, F) have been used. Our theoretical findings suggest that the doubly bonded SnYX species are always both kinetically and thermodynamically more stable than their corresponding triply bonded isomers, XSnY, regardless of the electronegativity of the substituent X. Nevertheless, our model calculations indicate that an aryl group can, if sufficiently bulky, stabilize triply bonded XSnY molecules with respect to both isomerization and polymerization. That is to say, it is not electronic but steric effects that play a dominant role in stabilizing both SnSb and SnBi triple bonds. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Testing the equality of two Poisson means using the rate ratio
Authors: Ng Hon Keung Tony , Tang Man‐Lai 
Published: November 2004

AbstractIn this article, we investigate procedures for comparing two independent Poisson variates that are observed over unequal sampling frames (i.e. time intervals, populations, areas or any combination thereof). We consider two statistics (with and without the logarithmic transformation) for testing the equality of two Poisson rates. Two methods for implementing these statistics are reviewed. They are (1) the sample‐based method, and (2) the constrained maximum likelihood estimation (CMLE) method. We conduct an empirical study to evaluate the performance of different statistics and methods. Generally, we find that the CMLE method works satisfactorily only for the statistic without the logarithmic transformation (denoted as W2) while sample‐based method performs better for the statistic using the logarithmic transformation (denoted as W3). It is noteworthy that both statistics perform well for moderate to large Poisson rates (e.g. ⩾10). For small Poisson rates (e.g. <10), W2 can be liberal (e.g. actual type I error rate/nominal level ⩾1.2) while W3 can be conservative (e.g. actual type I error rate/nominal level ⩽0.8). The corresponding sample size formulae are provided and valid in the sense that the simulated powers associated with the approximate sample size formulae are generally close to the pre‐chosen power level. We illustrate our methodologies with a real example from a breast cancer study. Copyright © 2004 John Wiley & Sons, Ltd.