bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling of electric‐stimulus‐responsive hydrogels immersed in different bathing solutions
Authors: Luo Rongmo , Li Hua , Birgersson Erik , Lam Khin Yong 
Published: August 2007

AbstractBy reformulation of the fixed charge density and consideration of finite deformation, a previous model simulating the pH‐sensitive hydrogels is refined in this paper for extension to simulating the electric‐sensitive hydrogels, which is termed the refined multi‐effect‐coupling electric‐stimulus (rMECe) model. The rMECe model is based on the assumptions: (a) the hydrogel is isotropic and macroscopically homogeneous, (b) all the three phases are incompressible, including the polymeric solid matrix, interstitial water and mobile ions, (c) the effect of electro‐osmosis is neglected, (d) bath solution is ideal so that the variation of the activity coefficients with ionic strength can be negligible, i.e., its effect on the concentration profiles is negligible, (e) the smart hydrogel is immersed in an unstirred solution in vibration‐free experimental device; the bulk flow of fluid or hydrodynamic velocity can thus be eliminated and subsequently the convective flux is neglected, and (f) the pore of the present hydrogel is narrow enough so that the diffusion dominates the transmission of flux. The model consists of nonlinear coupled partial differential governing equations with the coupling effects of chemo‐electro‐mechanical multi‐energy domains and the fixed charge density with the effect of externally applied electric‐field. By comparing the simulating results with experimental data extracted from literature, a very good agreement is achieved and thus this validates the computing accuracy and stability of model. The present rMECe model shows the capability of efficiently predicting the ionic transport and the performance of the hydrogels when they are immersed in a bath solution subject to externally applied electric voltage. The model is used for quantitative analysis of the electric‐sensitive hydrogels and for discussion of the influences of several physical parameters on the response of the hydrogels, including the externally applied electric voltage, the initially fixed charge density, and the ionic strength and valence of surrounding solution. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2008
Helper‐dependent adenovirus for the gene therapy of proliferative retinopathies: stable gene transfer, regulated gene expression and therapeutic efficacy
Authors: Lamartina Stefania , Cimino Monica , Roscilli Giuseppe , Dammassa Ernesta , Lazzaro Domenico , Rota Rossella , Ciliberto Gennaro , Toniatti Carlo 
Published: August 2007

AbstractBackgroundOcular neovascular disorders, such as diabetic retinopathy and age‐related macular degeneration, are the principal causes of blindness in developed countries. Current treatments are of limited efficacy, whereas a therapy based on intraocular gene transfer of angiostatic factors represents a promising alternative. For the first time we have explored the potential of helper‐dependent adenovirus (HD‐Ad), the last generation of Ad vectors, in the therapy of retinal neovascularization.MethodsWe first analyzed efficiency and stability of intraretinal gene transfer following intravitreous injection in mice. A HD‐Ad vector expressing green fluorescent protein (GFP) under the control of the cytomegalovirus (CMV) promoter (HD‐Ad/GFP) was compared with a first‐generation (E1/E3‐deleted) Ad vector carrying an identical GFP expression cassette (FG‐Ad/GFP). We also constructed HD‐Ad vectors expressing a soluble form of the VEGF receptor (sFlt‐1) in a constitutive (HD‐Ad/sFlt‐1) or doxycycline (dox)‐inducible (HD‐Ad/S‐M2/sFlt‐1) manner and tested their therapeutic efficacy upon intravitreous delivery in a rat model of oxygen‐induced retinopathy (OIR).ResultsHD‐Ad/GFP promoted long‐lasting (up to 1 year) transgene expression in retinal Müller cells, in marked contrast with the short‐term expression observed with FG‐Ad/GFP. Intravitreous injection of HD‐Ad vectors expressing sFlt‐1 resulted in detectable levels of sFlt‐1 and inhibited retinal neovascularization by more than 60% in a rat model of OIR. Notably, the therapeutic efficacy of the inducible vector HD‐Ad/S‐M2/sFlt‐1 was strictly dox‐dependent.ConclusionsHD‐Ad vectors enable stable gene transfer and regulated expression of angiostatic factors following intravitreous injection and thus are attractive vehicles for the gene therapy of neovascular diseases of the retina. Copyright © 2007 John Wiley & Sons, Ltd.
The cis/trans isomerization of Cu(II)–bis‐(glycinato) complex in solution: a computer aided multifrequency EPR and DFT/PCM calculation study
Authors: Pezzato M. , Lunga G. Della , Baratto M. C. , Sinicropi A. , Pogni R. , Basosi R. 
Published: August 2007

AbstractIn this paper the Cu(II)–bis‐(glycinato) complex has been analysed in solution by applying a combined approach of multifrequency EPR and DFT/PCM calculations. The accuracy in the determination of magnetic parameters has been reached by the use of a unique simulation program (COSMOS) for the whole range of temperatures analysed and by the error analysis. A change in magnetic parameters was envisaged in the 243–253 K range of temperature, and was interpreted in terms of stabilization, near the freezing point of the solution, of one of the isomers of the complex. A DFT/PCM computational model was crucial in assigning, on the basis of the experimental superhyperfine interaction value, the isomer to the trans form. Copyright © 2007 John Wiley & Sons, Ltd.
Fluorophore‐labeled myosin‐specific antibodies simplify muscle‐fiber phenotyping
Authors: Gregorevic Paul , Meznarich Norman A. , Blankinship Michael J. , Crawford Robert W. , Chamberlain Jeffrey S. 
Published: August 2007

AbstractSkeletal muscles are frequently analyzed for composition of phenotypically distinct myofibers, as a functional determinant. We describe an improved myofiber phenotyping procedure, involving cryosection co‐incubation with fluorophore‐labeled myosin heavy‐chain (MyHC)‐isoform–specific antibodies. This technique identifies multiple fiber “types” on a single section, thereby reducing reagents and processing, and offers side‐by‐side comparison of samples from multiple species including mice. These advances are valuable for studying the physiological attributes of skeletal muscle in health and disease. Muscle Nerve, 2007
Glucose‐induced de novo synthesis of fatty acyls causes proportional increases in INS‐1E cellular lipids
Authors: Nyblom H. K. , Nord L. I. , Andersson R. , Kenne L. , Bergsten P. 
Published: August 2007

AbstractRaised concentrations of glucose for extended periods of time have detrimental effects on the insulin‐producing β‐cell. As de novo synthesis of lipids has been observed under such conditions, it was hypothesized that newly formed lipids may preferentially contain saturated fatty acids, which in particular have been associated with impaired β‐cell function. Glucose‐induced de novo synthesis of fatty acids in INS‐1E cells cultured in 5.5, 11, 20 or 27 mM glucose for 5 days was assessed by high‐resolution magic‐angle‐spinning (HR‐MAS) NMR spectroscopy and gas chromatography‐mass spectrometry (GC‐MS). The glucose origin of the increase in fatty acyls was verified by replacing glucose with [1‐13C]glucose during culture followed by analysis with two‐dimensional 1H‐13C NMR spectroscopy. The composition of the fatty acyls was determined by GC‐MS. Fatty acyls determined by HR‐MAS 1H NMR spectroscopy were increased fivefold in INS‐1E cells cultured in 20 or 27 mM glucose compared with cells cultured in 5.5 mM glucose. The five most abundant fatty acids with their relative percentages in INS‐1E cells cultured in 5.5 mM glucose were oleate (33%), palmitate (25%), stearate (19%), octadecenoate (13%) and palmitoleate (4.4%). These proportions were not affected by glucose‐ induced de novo synthesis in INS‐1E cells cultured in 11, 20 or 27 mM glucose. It is concluded that glucose‐induced de novo lipid synthesis results in accumulation of both saturated and unsaturated fatty acids in specific proportions that are identical with those present under control conditions. Copyright © 2007 John Wiley & Sons, Ltd.
Electrical and microstructural properties of low‐resistance Ti/Re/Au ohmic contacts to n‐type GaN
Authors: Rajagopal Reddy V. , Choi Chel‐Jong 
Published: August 2007

AbstractThe microstructural and electrical properties of Ti/Re/Au (10 nm/10 nm/50 nm) ohmic contacts to moderately doped n‐type GaN (4.0 × 1018 cm–3) have been investigated by current–voltage (I –V), Auger electron microscopy (AES) and transmission electron microscopy (TEM). The electrical characteristics of as‐deposited and annealing at temperatures below 800 °C samples exhibit non‐linear behaviour. However, the sample showed ohmic behaviour when the contact is annealed at 900 °C for 1 min in nitrogen ambient. The Ti/Re/Au contacts give specific contact resistance as low as 8.6 × 10–6 Ω cm2 after annealing at 900 °C. It is shown that the surface of the as‐deposited contact is fairly smooth and slightly degraded when the contact is annealed at 900 °C. The Ti/Re/Au ohmic contact showed good edge acuity after annealing at 900 °C for 1 min. Based on the Auger electron microscopy and transmission electron microscopy results, possible ohmic formation mechanisms for the Ti/Re/Au contacts to the n‐type GaN are described and discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimization of aluminum‐doped ZnO thin‐film deposition by magnetron sputtering for liquid crystal display applications
Authors: Minami Tadatsugu , Miyata Toshihiro , Ohtani Yuusuke 
Published: August 2007

AbstractThis paper describes the optimization of ZnO:Al (AZO) thin films formed by a magnetron sputtering method for the purpose of creating a substitute for the indium‐tin‐oxide (ITO) transparent electrodes used in liquid crystal display (LCD) applications. New AZO thin‐film preparation techniques for both decreasing resistivity as well as improving resistivity distribution have been investigated: magnetron sputtering deposition in a weakly reducing atmosphere and newly developed high‐rate magnetron sputtering deposition techniques. A low resistivity below 5 × 10–4 Ω cm and improvement of the resistivity distribution could be obtained using a commercially available high density sintered AZO target by introducing hydrogen gas into the deposition chamber during depositions with a dc magnetron sputtering method that incorporates rf power. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tuning the shape of macroporous silicon
Authors: Trifonov T. , Garín M. , Rodríguez A. , Marsal L. F. , Alcubilla R. 
Published: August 2007

AbstractMacroporous silicon membranes, prepared by photo‐electrochemical etching, were subjected to pore widening performed by multiple oxidation/oxide‐stripping cycles. We study the dependence of pore cross section and diameter on the oxidation parameters. The anisotropy of the oxidation process allows us to correct the faceted pore shape after the etching and to obtain pores with circular cross section. The shown post‐treatment of macroporous silicon extends the possibilities of the electrochemical etching process to produce structures with a desired geometry. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An analytical approach to the tunnelling current of MOSFETs considering the barrier height reduction caused by the channel electron velocity due to the effective electron mass difference between silicon and oxide
Authors: Mao Ling‐Feng 
Published: August 2007

AbstractThe effects of the barrier height reduction caused by the channel electron velocity due to the effective electron mass difference between silicon and oxide on the gate leakage current in a MOSFET are discussed The calculations show such a barrier height reduction will have a large effect on the direct tunnelling current and the Fowler–Nordheim tunnelling current when the channel electron velocity is higher than 2 × 107 cm/s. The relative increase in the tunnelling current caused by such a barrier height reduction increases with increasing oxide electric field in the regime of the direct tunnelling, but decreases with increasing oxide electric field in the regime of the Fowler–Nordheim tunnelling. The A ‐factor in the Fowler–Nordheim expression increases but the B ‐factor decreases with channel electron velocity, and they remain constant when the channel electron velocity is less than 3 × 106 cm/s. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Luminescence of isoelectronically ion‐implanted SiO2 layers
Authors: Salh Roushdey , Fitting Kourkoutis L. , Schmidt B. , Fitting H.‐J. 
Published: August 2007

AbstractScanning electron microscopy (SEM) and cathodoluminescence (CL) in combination with scanning transmission electron microscopy (STEM) have been used to investigate thermally grown amorphous silicon dioxide layers implanted isoelectronically with group IV ions (C+, Si+, Ge+, Sn+, Pb+) as well as with group VI ions (O+, S+, Se+). Besides the main luminescent centers in a‐SiO2 layers: the red R luminescence (650 nm; 1.9 eV) of the non‐bridging oxygen hole centers (NBOHC), the blue B (460 nm; 2.7 eV) and the UV (290 nm; 4.3 eV) band of the oxygen deficient centers (ODC), in ion implanted silica additional emission bands are observed. E.g. in Ge+ implanted layers a huge violet band appears at 410 nm (3.1 eV) increasing with the thermal annealing process due to formation of Ge dimers, trimers or higher aggregates, finally leading to destruction of the luminescence centers by further growing to Ge nanoclusters. The Ge cluster size is shown by STEM cross section micrographs.Generally, group IV element implantation and partial substitution of silicon increases the luminescence in the blue/violet region whereas group VI elements and additional oxygen increase the intensity in the red region, confirming the association of the blue and the red luminescence with oxygen deficient centers and oxygen excess centers, respectively. Thus, the cathodoluminescence spectra of sulfur and oxygen implanted SiO2 layers under special conditions show besides the characteristic luminescence bands a multimodal structure beginning in the green region at 500 nm and extending up to the near infrared region at 820 nm. The energy step differences of the sublevels amount in the average 120 meV and indicate vibronic‐electronic transitions, probably of O2– interstitial molecules. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of substrate temperature on structural, optical and electrical properties of spray pyrolytically grown nanocrystalline SnO2 thin films
Authors: Chacko Saji , Sajeeth Philip Ninan , Vaidyan V. K. 
Published: August 2007

AbstractSnO2 nanocrystalline thin films were prepared by a spray pyrolysis method on glass substrates at 375, 400, 425, 450 and 500 °C. Structural, optical and electrical properties of these films were studied by X‐ray diffraction, UV–visible and four‐probe methods. The change in electrical conductivity, band gap and optical transmittance was found to be a function of the change in lattice parameters Δa and Δc The samples prepared at 425 °C are found to have good figure of merit and maximum transmittance (96% at 550 nm). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Exploring and mapping Fermi surfaces of complex materials
Authors: Dugdale S. B. 
Published: August 2007

AbstractThe study of the electronic structure of crystalline materials, and specifically metallic systems, has formed the backbone of physics in the solid state. Our vision of the electronic ground state of a metallic system is dominated by the concept of the Fermi surface, which dictates many of the material properties. The momentum distribution can give invaluable access to information about the Fermi surface topology, and both positron annihilation and Compton scattering experiments can measure it. Here, recent progress in the field is discussed and illustrated with appropriate examples. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of the curing temperature on the structure of epoxy/rectorite nanocomposites studied by positrons
Authors: Chen Z. , Liu L. M. , Fang P. F. , Wang H. M. , Wang S. J. 
Published: August 2007

AbstractThe epoxy‐rectorite nanocomposites were prepared at different curing temperature ranged from 70 °C to 200 °C and the effects of curing temperature on microstructure of material have been studied by positron annihilation lifetime spectroscopy (PALS), and X‐ray diffraction (XRD). The XRD patterns show that the intercalated structure existed in the samples cured at 70 °C and 90 °C, and the clay platelets were completely exfoliated while the curing temperature is higher than 110 °C. At low rectorite content the Ps is mainly formed and annihilated in the free volume of the epoxy matrix and the average size of the free volume is essentially unchanged with the curing temperature. With the increasing curing temperature from 70 °C to 110 °C, the dramatic increase in the intensity I2 of second lifetime component indicates the formation of interfacial layers between rectorite and epoxy matrix. The distributions of o‐Ps lifetime and the free volume size have the narrowest distribution for the samples cured at temperature 110 °C and 140 °C, which imply the most homogeneous structure existed in the nanocomposites. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Internal surfaces of voids and cavities in silicon probed by Positron Annihilation Spectroscopy
Authors: Potter N. R. , Coleman P. G. 
Published: August 2007

AbstractSilicon with a layer of helium created nanovacanies is probed using Positron Annihilation Spectroscopy. Analysis of theS‐parameter and Gaussian fitting of the full γ‐energy spectra shows trapping in cavities both clean and oxygen‐decorated. Repeated measurements at 700 °C suggest that trapping may be occuring in smaller voids surrounding the nanovacancies themselves. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of hydrogen bonding on low temperature positronium formation in frozen hexanol
Authors: Suzuki T. , Yu R. S. , Shantarovich V. P. , Ito Y. , Kondo K. 
Published: August 2007

AbstractThe increase of positronium (Ps) formation in polymers (polyethylene and PMMA) cooled below the freezing temperature of molecular motions has been widely accepted to be due to positron interaction with weakly bound (trapped) electrons. For the first time, we will present results on a more complicated effect for monomers: in frozen hexanol below 100 K increase of ortho‐Ps intensity (I3) with elapsed time of the experiment could be inhibited by bleaching and therefore had the traditional explanation. However, around 200 K the increase of I3 with elapsed time was not affected by light and had different nature, namely, reducing of inhibition effect due to formation of hydrogen bonds typical for the solid state structure. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Temperature dependence of the free volume holes in polyhydroxybutyrate biopolymer: A positron lifetime study
Authors: Abdel‐Hady E. E. , Mohamed Hamdy F. M. , Fareed Somia S. 
Published: August 2007

AbstractThe size of the free volume holes and their distributuion in polyhydroxybutyrate (PHB) biopolymer have been studied using positron annihilation lifetime spectroscopy (PALS). The measurements were performed as a function of the temperature from 243 to 363 K. The temperature dependence of the free volume hole shows a glass transition temperature, Tg at 278 K. The free volume behaviour of PHB shows a small linear increase with temperature below Tg and a steeper increase above Tg. The thermal expansion coefficients of the free volume hole were determined to be 4.78 x 10–3 and 12.5 x 10–3 / K below and above Tg, respectively. The free volume hole distribution shows a narrow distribution below Tg. With increasing temperature, the maximum of the distributions of the free volume holes shifts to higher values. Meanwhile, widening of the distribution is smaller in lower temperature ranges and more pronounced at higher temperatures, especially above Tg. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermal evolution of vacancy defects induced in 12 MeV H+ irradiated 6H‐SiC single crystals
Authors: Kerbiriou X. , Barthe M.‐F. , Gentils A. , Desgardin P. 
Published: August 2007

AbstractIn this work positron annihilation lifetime spectroscopy (PALS) has been used to investigate the evolution of the vacancy defects induced in 12 MeV H+ irradiated SiC as a function of the temperature. The irradiation has been performed at room temperature at a fluence of 4 x 1016 cm–2 in 6H‐SiC single crystals using the CERI‐Orléans cyclotron. Thermal treatments have been performed under an argon flux from 300 °C up to 1050°C. The positron lifetime has been measured as a function of the temperature in the range 15–600 K. After irradiation, positrons detect negative ions and two types of vacancy defects: VSi monovacancies and VSi–VC divacancies. After annealing, the lifetime behaviour as a function of the measurement temperature changes indicating different annealing stages. An increase of the long lifetime component is specially observed whereas the corresponding intensity decreases. These changes are correlated to the migration of VSi and the clustering with VSi–VC to form a new vacancy defect. The lifetime of this new defect has been determined and is equal to 235 ± 2 ps. We propose that it is related to VSi–VC–VSi. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Positron annihilation study of alloys for fission and fusion technology
Authors: Slugen Vladimir , Krsjak Vladimir , Petriska Martin , Zeman Andrej , Miklos Marek 
Published: August 2007

AbstractPositron annihilation spectroscopy (PAS) based on positron lifetime measurements using the conventional positron annihilation lifetime set‐up and the Pulsed Low Energy Positron System (PLEPS) was applied for the investigation of defects of irradiated and thermally treated reactor pressure vessel (RPV) steels as well as for investigation of new materials foreseen for Generation‐IV and fusion facilities. PAS results obtained in framework of several scientific projects are summarised and correlated to other techniques. Possibilities for experimental modelling of irradiation effects using ion implantation instead of neutron irradiation are discussed in the paper. The actually running program of micro structural study of Fe–Cr binary alloys is presented in detail. For the next effective study of radiation degradation of fusion as well as fission materials, the experimental micro structural study of model alloys in combination to computer simulations is recommended. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coincidence Doppler broadening study of phase decomposition in a continuous cast AA 2037 Al alloy
Authors: Wu Y.C. , Wu S.L. , Chen Y.Q. , Wang S.J. , Zhai T. 
Published: August 2007

AbstractPhase decomposition in hot band of a continuous cast AA 2037 Al alloy was investigated by coincidence Doppler broadening (CDB) of positron annihilation radiation and positron annihilation lifetime spectroscopy (PALS). It was found that there existed V–Cu and V–Cu–Mg complexes in the as‐received hot band at room temperature. At 200°C, positron average lifetime appeared to be a maximum value because of the formation of semi‐coherent precipitates. The shape of the CDB ratio curve was found to be characteristic of Mn, which indicated the formation of V‐Mn complexes or the existence of Mn clusters in the semi‐coherent precipitates. Above 250 °C, coarsening and dissolution of semi‐coherent precipitates resulted in a decrease in lifetime and disappearance of the Mn signal, but the Cu signal increased clearly with increase in annealing temperature. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)