bluuebunny/crossref_metadata_2025 huggingface dataset:
Annealing Effect of Ce-Doped CaGa2S4 Synthesized by Mechanochemical Solid-State Reaction
Authors: Ohta Takumi , Tanaka Kunihiko , Uchiki Hisao
Published: May 2011

The effect of annealing on samples prepared by ball milling of a mixture of CaS, Ga2S3, and Ce2S3 powders was investigated. When the mixture of powders was ball-milled for 1 h, no crystalline CaGa2S4:Ce was formed, and by subsequent annealing at 400 °C, CaGa2S4:Ce crystallites were formed. When the mixture powder was ball-milled for 5 h, nanometer-sized CaGa2S4:Ce crystallites were mechanochemically synthesized without heat treatment. By subsequent annealing of the crystallites at several temperatures from 300 to 800 °C, the strain on the mechanochemically synthesized Ce-doped CaGa2S4 nanometer-sized crystallites was removed and crystallites of about dozens of nanometer size were retained by 500 to 600 °C annealing.
Growth of γ-In2Se3 Thin Films by Electrostatic Spray Pyrolysis Deposition
Authors: Kato Takamasa , Hiramatsu Toshitaka , Onojima Norio
Published: May 2011

γ-In2Se3 thin films were grown by the electrostatic spray pyrolysis deposition growth technique. We investigated the dependence of the crystalline quality and optical properties of the grown films on the growth conditions, such as growth temperatures and the molar ratios of source material Se/In in the precursor solution. The films which were highly aligned to the c-axis were grown at low growth temperature of 250 °C on glass substrates. The optical band gap energy was about 1.94 eV and was independent of the growth temperatures and the molar ratios Se/In in the precursor solution.
Effects of Ga Doping and Substrate Temperature on Electrical Properties of ZnO Transparent Conducting Films Grown by Plasma-Assisted Deposition
Authors: Matsumoto Takashi , Mizuguchi Keiichi , Horii Takahiro , Sano Shiho , Muranaka Tsutomu , Nabetani Yoichi , Hiraki Satoshi , Furukawa Hideaki , Fukasawa Akihiro , Sakamoto Shingo , Hagihara Shigeru , Kono Hiroshi , Kijima Kazuhiro , Abe Osamu , Yashiro Kouji
Published: May 2011

Transparent conducting ZnO films are deposited by plasma-assisted deposition on glass and plastic substrates at temperatures as low as 50 °C. The effects of Ga doping and growth temperature on electrical properties are studied using Hall measurement and X-ray diffraction. Carrier density increases with Ga doping for both 50 and 300 °C growth. For low-temperature growth, the carrier mobility in undoped ZnO films is the same as that in high-temperature-grown films, but it becomes lower as the Ga doping level becomes higher. Lattice expansion in both c and a axes directions is observed for low-temperature-grown highly Ga-doped films. The relation between the mobility reduction and the lattice expansion is discussed.
Characteristic of Low Resistivity Fluorine-Doped SnO2 Thin Films Grown by Spray Pyrolysis
Authors: Oshima Minoru , Yoshino Kenji
Published: May 2011

Transparent conducting oxide films of fluorine-doped SnO2 (FTO) were deposited on glass substrates by spray pyrolysis in order to determine the effect of spray solution concentration. These films were prepared with different F-doping concentrations from 0 to 33 mol %. The films were all polycrystalline with tetragonal crystal structures. The best electro-optic properties were achieved with a fluorine doping concentration of 17 mol % at a substrate temperature of 500 °C. These conditions resulted in a film with an average transmittance of 82%, a resistivity of 4.0 ×10-4 Ω cm, a carrier concentration of 4.7 ×1020 cm-3 and a mobility of 34 cm2 V-1 s-1.
Time-Resolved Microphotoluminescence Study of Cu(In,Ga)Se2
Authors: Sakurai Takeaki , Taguchi Keiki , Islam Muhammad Monirul , Ishizuka Shogo , Yamada Akimasa , Matsubara Koji , Niki Shigeru , Akimoto Katsuhiro
Published: May 2011

The carrier recombination processes in Cu(In1-x
,Ga
x
)Se2 (CIGS) thin films were investigated by time-resolved microscopic-photoluminescence (µ-PL) measurement at room temperature. For films with x = 0.45, the spatial distribution of the donor–acceptor pair luminescence is much larger than the grain size. The PL decay lifetime is directly correlated with the µ-PL intensity, but the spectral shape is identical regardless of the sample position. These results suggest that the nonuniform distribution of nonradiative recombination centers mainly affects the carrier recombination in CIGS thin films. At relatively high Ga concentrations (x ≥0.7), the spatial inhomogeneity in µ-PL intensity is enhanced and decay accelerated, suggesting an increase in the density of nonradiative recombination centers. Thus, suppression of nonradiative recombination is critical to enhancing the performance of CIGS-based solar cells.
Photoluminescence of Cu(In,Ga)Se2 in the Solar Cell Preparation Process
Authors: Shirakata Sho , Yudate Shinji , Honda Jyunji , Iwado Naoki
Published: May 2011

Room-temperature photoluminescence (PL) has been studied in Cu(In,Ga)Se2 (CIGS) films with emphasis on the near-band-edge PL of CIGS during the solar cell fabrication process. A step-by-step PL spectrum mapping measurement was carried out on the following cell processes: depositions of CIGS absorber, CdS buffer, high-resistivity undoped ZnO buffer, and low-resistivity Al-doped window ZnO layers, and the final cell separation process by mechanical scribing. The systematic change in PL intensity during the process has been studied, and the usefulness of PL as a noncontact process monitor has been demonstrated.
Excited States of the A and B Free Excitons in CuInSe2
Authors: Yakushev Michael V. , Luckert Franziska , Faugeras Clement , Karotki Anatoli V. , Mudryi Alexander V. , Martin Robert W.
Published: May 2011

CuInSe2 single crystals, grown by the vertical Bridgman technique were studied using polarisation resolved photoluminescence (PL) at cryogenic temperatures. The emission lines related to the first (n = 2) excited states for the A and B free excitons were observed in the PL spectra at 1.0481 and 1.0516 eV, respectively. The spectral positions of these lines were used to estimate accurate values for the A and B exciton binding energies (8.5 and 8.4 meV, respectively), Bohr radii (7.5 nm), band gaps (E
g
A = 1.050 eV and E
g
B = 1.054 eV), and the static dielectric constant (11.3) assuming the hydrogenic model.
Three-Dimensional Atomic Images of TlInSe2 Thermoelectric Material Obtained by X-ray Fluorescence Holography
Authors: Hosokawa Shinya , Happo Naohisa , Hayashi Kouichi , Mimura Kojiro , Wakita Kazuki , Hu Wen , Ishii Hirofumi , Yoshimura Masato , Jeyakanthan Jeyaraman , Mamedov Nazim
Published: May 2011

Three-dimensional (3D) atomic images around the Tl atoms in single-crystal TlInSe2 thermoelectric material in the incommensurate phase were reconstructed by Tl L
III X-ray fluorescence holography measured at room temperature. In the obtained 3D image, the In atoms are clearly visible at the proper positions in the normal phase. The Tl atomic images are also observed but very weakly. By comparing the experimental image with a theoretically calculated one, it is concluded that only the Tl atoms have large spatial fluctuations, which are related to the incommensurate phase of this material.
Superionic Conductivity in One-Dimensional Nanofibrous TlGaTe2 Crystals
Authors: Sardarly Rauf , Samedov Oktay , Abdullayev Adil , Salmanov Famin , Urbanovic Andzej , Garet Frédéric , Coutaz Jean-Louis
Published: May 2011

We study the temperature dependence of the electrical conductivity σ(T) of TlGaTe2 crystals under an electric field (E = 181 V/cm). A strong sharp increase (×1500) in σ(T) is observed at T = 242 K (along the c-axis) and T = 267 K (perpendicular to it). This increase is attributed to a transition towards a superionic conductivity behavior. Over the superionic transition threshold, disordering of the Tl+ sublattice in TlGaTe2 occurs, and nanoscale topological disordering arises owing to aperiodicity in placing Ga3+Te2
2- nanofibers. Terahertz time-domain spectroscopy reveals absorption lines at approximately 0.2 THz that may be attributed to the libration oscillations of the nanofibers.
γ-Radiation Stimulated Structural Transition of Monoclinic TlInS2 to Hexagonal Phase
Authors: Alekperov Oktay , Mamedov Nazim , Safarov Nuru , Gasumov Vagif , Nadjafov Arzu
Published: May 2011

Temperature dependent dielectric function and conductivity, as well as room temperature photoconductivity have been investigated on monoclinic TlInS2 subjected to γ-radiation in a wide range of radiation doses. The structural changes have been detected by XRD performed after every stage of γ-irradiation. Frenkel pairs (vacancies and interstitial sulfur atoms) have been assumed to appear in TlInS2 at irradiation doses below 100 Mrad through well-known Klinger's “residual charged impurity assisted electrostatic” mechanism. These defects eventually lead to the formation of neutral impurity complexes responsible for the observed sharpening of the anomalies in dielectric function and conductivity at the temperature of the well-known ferroelectric phase transition in TlInS2. The last anomalies become smeared out at irradiation doses above 200 Mrad. Finally, the transformation of the monoclinic TlInS2 to the one with hexagonal structure has been witnessed in a thin surface layer at high fluencies (1000–1500 Mrad) of γ-radiation.
Spin–Orbit Interactions in a Quasi-Two-Dimensional Electron Gas with Finite Thickness
Authors: Nakhmedov Enver , Alekperov Oktay , Oppermann Reinhold
Published: May 2011

Effects of the spin–orbit coupling on the energy spectrum, Fermi surface and spin dynamics are studied in structural- and bulk-inversion asymmetric quasi-two-dimensional structures with a finite thickness in the presence of a parabolic transverse confining potential. One-particle quantum mechanical problem in the presence of an in-plane magnetic field is solved numerically exact. Interplay of the spin–orbit interactions, orbital- and Zeeman-effects of the in-plane magnetic field results in a formation of a multi-valley subband structure, typical for realization of the Gunn effect. A possible Gunn-effect-mediated spin accumulation is discussed. The spin–orbit interactions and in-plane magnetic field are shown to change the regular plateau structure of the ballistic conductance.
Ab initio Lattice Dynamics and Grüneisen Parameters of TlGaSe2
Authors: Huseinova Dilara A. , Hashimzade Firudin M. , Orudzhev Guseyin S. , Nizametdinova Munira A. , Allakhverdiev Kerim R.
Published: May 2011

The first-principles calculations of the lattice dynamics of the TlGaSe2 ternary semiconductor compound are presented in this paper. Calculations were performed using open-source code ABINIT on the basis of the density functional perturbation theory within the plane-wave pseudopotential approach. Results on the frequencies of phonon modes in the centre of Brillouin zone and the dispersion of transverse shear acoustic branch of the phonon spectra agree well with experimental data on Raman scattering, infrared reflectivity and ultrasound wave propagation in TlGaSe2. The calculated and experimental temperature dependencies of heat capacity are in a good agreement up to the room temperature. Along the layer, the low-frequency acoustic branch displays the bending wave behavior which is characteristic of the layer crystal structures. We have calculated also the elastic compliances tensor, the directional Grüneisen functions and the coefficients of the linear thermal expansion for TlGaSe2. We obtained that both principal components of the coefficients of linear expansion are positive in the range of temperature above 5 K.
Ab initio Phonons in Magnetic Ni2MnAl
Authors: Isaeva Leyla , Bazhanov Dmitry , Isaev Eyvaz , Eriksson Olle
Published: May 2011

In the present work we report the results of ab initio studies of electronic and dynamic properties of nickel based Heusler alloy Ni2MnAl. The total magnetic moment and elastic constants were also evaluated and compared to experimental results where possible. We found that the phonon dispersion relations calculated in this work within the linear response method did not reveal any softening of the transversal acoustic mode TA2 along [ξ, ξ, 0] direction in accordance with the experiment and in controversy to previous theoretical studies.
Influence of Exchange Interaction on Phonon–Polaron Properties in Diluted Magnetic Semiconductors
Authors: Seyid-Rzayeva Seyid-Nisa M.
Published: May 2011

The energy spectrum of a phonon–polaron effect with weak coupling has been obtained in the classical magnetic field for diluted magnetic semiconductors, which has a cubic crystal structure with a one-valley anisotropic energy spectrum of the band electrons. Analytical expressions for polaron binding energy and lowest polaron subband energy (i.e., polaron ground-state energy of the lowest conduction subband with spin ↓), and the transverse and longitudinal polaron effective masses of the electron in the dependence on the magnetic field were found. On the basis of quantitative calculations, it has been established that with increasing magnetic field, polaron binding energy is decreased owing to the exchange interaction. Also, it has been established that the lowest polaron subband energy is shifted down in energy; at the same time, the bottom of the lowest polaron subband energy is located much lower compared with the bottom of the polaron band for the standard spectrum.
Entropy of Superlattices in a Quantized Magnetic Field
Authors: Askerov Bahram M. , Figarova Sophia R. , Mahmudov Mehdi M. , Figarov Vagif R.
Published: May 2011

The entropy of a degenerate and a nondegenerate low dimensional electron gas in a quantized magnetic field is calculated. It is noted the entropy of a two-dimensional electron gas essentially exceeds entropy of three-dimensional electron gas. It is shown the entropy of a degenerate quasi-two-dimensional electron gas is directly proportional to the state density. The ratio of entropy of a degenerate two-dimensional electron gas to entropy of three-dimensional electron gas in the quantum limit is determined by the ratio of effective masses across and along layers.
Phase Stability and Electronic Structure of In-Free Photovoltaic Materials Cu2IISnSe4 (II: Zn, Cd, Hg)
Authors: Nakamura Satoshi , Maeda Tsuyoshi , Wada Takahiro
Published: May 2011

We have theoretically evaluated the phase stability and electronic structure of Cu2CdSnSe4 and Cu2HgSnSe4 and compared the results with those of Cu2ZnSnSe4. The enthalpies of formation for kesterite (KS), stannite (ST), and wurtz-stannite (WST) phases of Cu2ZnSnSe4 (CZTSe), Cu2CdSnSe4, and Cu2HgSnSe4 were calculated by first-principles calculations. In Cu2CdSnSe4 and Cu2HgSnSe4, the stannite (ST) phase is the most stable among these phases. The valence band maximum (VBM) of ST-type Cu2CdSnSe4 consists of antibonding orbitals of Cu 3d and Se 4p, while the conduction band minimum (CBM) consists of antibonding orbitals of Sn 5s and Se 4p. The VBM of Cu2HgSnSe4 also consist of antibonding orbitals of Cu 3d and Se 4p. However, the CBM of Cu2HgSnSe4 consists of antibonding orbitals of Hg 6s, Sn 5s, and Se 4p.
Analysis of the Enhancing Effect of Rare Earth Ion Co-Doping on the Red Emission of CaGa2S4:Mn2+ in View of Its Decay Time
Authors: Suzuki Akihiro , Hidaka Chiharu , Takizawa Takeo , Nomura Shigetaka
Published: May 2011

When certain trivalent rare earth elements (REEs) are co-doped with Mn2+ in CaGa2S4, the Mn2+ red emission of the compounds is enhanced. To clarify its mechanism, its decay curves of the Mn2+ red emission from CaGa2S4:Mn2+, REE3+ are investigated. For these analyses, we present a tentative transition model including the trap levels due to REE3+ together with a process enabling electron supply from REE3+ to the excited 3d state of Mn2+. This model can explain the enhancing effect on the Mn2+ red emission.
Effect of Ho Co-Doping on the Long Lasting Emission of CaGa2S4:Eu
Authors: Hidaka Chiharu , Takizawa Takeo
Published: May 2011

To investigate the long-lasting green afterglow from Ho added CaGa2S4:Eu compounds, photoluminescence (PL) and photoluminescence excitation (PLE) spectra are measured as a function of Ho concentration by keeping Eu one at 0.1 and 0.5 mol %. As Ho concentration increases, PL intensity of Eu decreases. PL from Ho at 660 nm has an additional broad excitation band ranging from 400 to 500 nm, emerging only if Eu2+ ion is co-doped. Since this new band just coincides with the Eu2+ emission in energy, electrons excited to the 5d states of Eu2+ are considered to transfer to the Ho excited states, which are actually confirmed by the weakened Eu emission observed. In the decay curve of Eu emission in a co-doped sample, two long-lasting components are observed. Their lifetimes, however, steeply decrease when Ho concentration increases more than 1 mol %. In this paper, energy transfer between the two dopants is discussed.
Control of Self-Focusing and Self-Defocusing in the Waveguides Array
Authors: Aghdami Keivan M. , Gharaati Abdolrasoul , Mokhtari Fatemeh
Published: May 2011

In this paper, propagation of a Gaussian beam through a one-dimensional array of optically coupled waveguides is investigated using numerical simulation. The results show that the propagation of light is strongly depended on the phase difference of the beams on the entrance face of waveguides. Also, the effect of nonlinear Kerr phenomenon is investigated in such media. Considering this effect, sometimes the slope of divergence is reduced in beam which is occurred because of diffraction, but sometimes depends on initial tilt of the beam, which exhibits an increase in divergence.
Controlling and Stabilizing of Thermally Travelling Optical Structures in Semiconductor Microresonators
Authors: Kheradmand Reza , Montazeri Najmeh
Published: May 2011

In this paper, controlling and stabilizing the thermally travelling patterns in a semiconductor multiple quantum-well microresonator that driven by a coherent holding beam has been studied. The presence of thermal effects introduces a Hopf instability which in certain regions of the parameter space dominates the dynamics of the system. The oscillatory instabilities can develop a modulational character, meaning that travelling patterns can be found. These phenomena develop over the slow timescale (microseconds) characterizing thermal effects in the devices. We investigated a method for stabilizing and switching the travelling patterns by using spatial perturbation, which can be used as an all optical switch.
Effect of “CdCl2 Treatment” on Properties of CdTe-Based Solar Cells Prepared by Physical Vapor Deposition and Close-Spaced Sublimation Methods
Authors: Hajimammadov Rashad , Fathi Nasser , Bayramov Ayaz , Khrypunov Genady , Klochko Nataliya , Li Tatyana
Published: May 2011

CdTe is regarded as one of the most promising materials for fabricating CdTe/CdS thin film solar cells with efficiencies up to 16.5%. In this paper we present a comparative analysis of CdTe-based solar cells fabricated by physical vapor deposition (PVD) and close-spaced sublimation (CSS) methods. The structural properties of CdTe base layers and the output parameters of CdS/CdTe solar cells are presented, and the influence of “CdCl2-treatment” on these properties are discussed. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses were used in the studies.
Comparison of the Valence Band Structure Peculiarities in the Bi0.84–Sb0.16–Sn0.1 and Pure Semiconducting Bi1-xSbx Alloys
Authors: Tairov Bakir , Yuzbashov Eltaj
Published: May 2011

On the basis of measured low magnetic field galvanomagnetic coefficients both for Sn-doped Bi0.84–Sb0.16–Sn0.1 and pure semiconducting Bi–Sb alloys, kinetic parameters of the investigated materials have been determined. It is shown that hole ellipsoids corresponding to the obtained results are less anisotropic (ν2/ν1 = 0.05, ν3/ν1 = 0.5) in comparison with L-hole ellipsoids, where ν2/ν1 = 0.009, ν3/ν1 = 0.7 and their slope is significantly larger (φh = 16°) than L-hole (and L-electron) ones. Therefore peculiarities of the valence band for the Bi0.84–Sb0.16 alloy and other semiconducting alloys with high content of antimony can not be adequately described by involving dominant contribution of the hole valleys localized in T, H, and L points of the Brioullin zone.
Schlafen-3 decreases cancer stem cell marker expression and autocrine/juxtacrine signaling in FOLFOX-resistant colon cancer cells
Authors: Oh Phil-Sun , Patel Vaishali B. , Sanders Matthew A. , Kanwar Shailender S. , Yu Yingjie , Nautiyal Jyoti , Patel Bhaumik B. , Majumdar Adhip P. N.
Published: May 2011

We have previously demonstrated that expression of the novel gene schlafen-3 (Slfn-3) correlates with intestinal epithelial cell differentiation (Patel VB, Yu Y, Das JK, Patel BB, Majumdar AP. Biochem Biophys Res Commun 388: 752–756, 2009). The present investigation was undertaken to examine whether Slfn-3 plays a role in regulating differentiation of FOLFOX-resistant (5-fluorouracil + oxaliplatin) colon cancer cells that are highly enriched in cancer stem cells (CSCs). Transfection of Slfn-3 in FOLFOX-resistant colon cancer HCT-116 cells resulted in increase of alkaline phosphatase activity, a marker of intestinal differentiation. Additionally, Slfn-3 transfection resulted in reduction of mRNA and protein levels of the CSC markers CD44, CD133, CD166, and aldehyde dehydrogenase 1 in both FOLFOX-resistant HCT-116 and HT-29 cells. This was accompanied by decreased formation of tumorosphere/colonosphere (an in vitro model of tumor growth) in stem cell medium and inhibition of expression of the chemotherapeutic drug transporter protein ABCG2. Additionally, Slfn-3 transfection of FOLFOX-resistant HCT-116 and HT-29 cells reduced Hoechst 33342 dye exclusion. Finally, Slfn-3 transfection inhibited the expression of transforming growth factor-α in both FOLFOX-resistant colon cancer cells, but stimulated apoptosis in response to additional FOLFOX treatment. In summary, our data demonstrate that Slfn-3 expression inhibits multiple characteristics of CSC-enriched, FOLFOX-resistant colon cancer cells, including induction of differentiation and reduction in tumorosphere/colonosphere formation, drug transporter activity, and autocrine stimulation of proliferation. Thus Slfn-3 expression may render colon CSCs more susceptible to cancer chemotherapeutics.
Exercise training improves endothelial function via adiponectin-dependent and independent pathways in type 2 diabetic mice
Authors: Lee Sewon , Park Yoonjung , Dellsperger Kevin C. , Zhang Cuihua
Published: May 2011

Type 2 diabetes (T2D) is a leading risk factor for a variety of cardiovascular diseases including coronary heart disease and atherosclerosis. Exercise training (ET) has a beneficial effect on these disorders, but the basis for this effect is not fully understood. This study was designed to investigate whether the ET abates endothelial dysfunction in the aorta in T2D. Heterozygous controls (m Lepr db) and type 2 diabetic mice ( db/db; Lepr db) were either exercise entrained by forced treadmill exercise or remained sedentary for 10 wk. Ex vivo functional assessment of aortic rings showed that ET restored acetylcholine-induced endothelial-dependent vasodilation of diabetic mice. Although the protein expression of endothelial nitric oxide synthase did not increase, ET reduced both IFN-γ and superoxide production by inhibiting gp91phox protein levels. In addition, ET increased the expression of adiponectin (APN) and the antioxidant enzyme, SOD-1. To investigate whether these beneficial effects of ET are APN dependent, we used adiponectin knockout (APNKO) mice. Indeed, impaired endothelial-dependent vasodilation occurred in APNKO mice, suggesting that APN plays a central role in prevention of endothelial dysfunction. APNKO mice also showed increased protein expression of IFN-γ, gp91phox, and nitrotyrosine but protein expression of SOD-1 and -3 were comparable between wild-type and APNKO. These findings in the aorta imply that APN suppresses inflammation and oxidative stress in the aorta, but not SOD-1 and -3. Thus ET improves endothelial function in the aorta in T2D via both APN-dependent and independent pathways. This improvement is due to the effects of ET in inhibiting inflammation and oxidative stress (APN-dependent) as well as in improving antioxidant enzyme (APN-independent) performance in T2D.
Acute hemorrhagic shock decreases airway resistance in anesthetized rat
Authors: Bayat Sam , Albu Gergely , Layachi Skander , Portier Flore , Fathi Marc , Peták Ferenc , Habre Walid
Published: May 2011

We studied the relation between changes in pulmonary and systemic hemodynamics to those in the airway resistance, respiratory tissue mechanics, and thoracic gas volume (TGV) following acute hemorrhage and blood reinfusion in rats. Forced oscillation technique was used to measure airway resistance (Raw), respiratory tissue damping, and elastance at baseline and after stepwise 1-ml blood withdrawals up to 5 ml total, followed by stepwise reinfusion up to full restoration. Mean systemic (Pam) and pulmonary arterial pressures and suprarenal aortic blood flow were measured at each step. In supplemental animals, plethysmographic TGV, Pam, and respiratory mechanics measurements were performed. Blood volume loss (BVL) led to proportional decreases in Raw (66.5 ± 8.8 vs. 44.8 ± 9.0 cmH2O·s·l−1 with 5 ml, P < 0.001), Pam, and aortic blood flow. In contrast, tissue damping increased significantly (1,070 ± 91 vs. 1,235 ± 105 cmH2O/l, P = 0.009 with 5 ml BVL), whereas tissue elastance did not change significantly. TGV significantly increased with acute BVL (3.7 ± 0.2 vs. 4.2 ± 0.2 ml, P = 0.01). Stepwise reinfusions produced opposite changes in the above parameters, with Raw reaching a higher value than baseline ( P = 0.001) upon full volume restoration. Both adrenalin ( P = 0.015) and noradrenalin levels were elevated ( P = 0.010) after 5-ml blood withdrawal. Our data suggest that the decreases in Raw following BVL may be attributed to the following: 1) an increased TGV enhancing airway parenchymal tethering forces; and 2) an increase in circulating catecholamines. The apparent beneficial effect of a reduction in Raw in acute hemorrhagic shock is counteracted by an increase in dead space and the appearance of peripheral mechanical heterogeneities due to de-recruitment of the pulmonary vasculature.
A mathematical modeling approach to risk assessment for normal and anemic women chronically exposed to carbon monoxide from biomass-fueled cookstoves
Authors: Bruce Eugene N. , Bruce Margaret C. , Erupaka-Chada Kinnera
Published: May 2011

In developing countries, the chronic exposure to carbon monoxide (CO) from biomass-fueled cookstoves may pose a significant health risk for women who use these stoves, especially for those with underlying clinical conditions that impair tissue oxygenation, e.g., anemia and coronary artery disease. CO concentrations measured in the vicinity of these cookstoves often exceed World Health Organization (WHO) indoor air guidelines for an 8-h average (9 ppm) and a 1-h maximum (26 ppm). Carboxyhemoglobin levels, reported infrequently because they are difficult to obtain, often exceed the WHO threshold of 2.5%. Despite this evidence, specific adverse effects have not yet been linked with chronic CO exposures in these women. Furthermore, anemia, which is prevalent in populations that use biomass fuels, could exacerbate the adverse effects of chronic CO exposure. Because of the difficulties inherent in conducting prospective studies to address this issue, we used a mathematical model to calculate the effects of reported CO levels and exercise on carboxyhemoglobin for women living in 1) Guatemalan villages at altitudes of 4,429–4,593 ft, and 2) coastal villages in Pakistan. In addition, we used the model to calculate the effects of CO exposures in women with moderate to severe anemia on specific physiological parameters (carboxyhemoglobin, carboxymyoglobin, cardiac output, and tissue Po2) at exercise levels representing the activities in which these women would be engaged. Our results demonstrate the efficacy of using a mathematical model to predict the physiologic responses to CO and also demonstrate that chronic anemia is a critically important determinant of CO toxicity in these women.
Nav1.4 and Nav1.5 are modulated differently during muscle immobilization and contractile phenotype conversion
Authors: Rannou Fabrice , Pennec Jean-Pierre , Morel Julie , Guéret Gildas , Leschiera Raphaël , Droguet Mickaël , Gioux Maxime , Giroux-Metges Marie-Agnès
Published: May 2011

Muscle immobilization leads to modification in its fast/slow contractile phenotype. Since the properties of voltage-gated sodium channels (Nav) are different between “fast” and “slow” muscles, we studied the effects of immobilization on the contractile properties and the Navof rat peroneus longus (PL). The distal tendon of PL was cut and fixed to the adjacent bone at neutral muscle length. After 4 or 8 wk of immobilization, the contractile and the Navproperties were studied and compared with muscles from control animals (Student's t-test). After 4 wk of immobilization, PL showed a faster phenotype with a rightward shift of the force-frequency curve and a decrease in both the Burke's index of fatigability and the tetanus–to-twitch ratio. These parameters showed opposite changes between 4 and 8 wk of immobilization. The maximal sodium current in 4-wk immobilized fibers was higher compared with that of control fibers (11.5 ± 1.2 vs. 7.8 ± 0.8 nA, P = 0.008), with partial recovery to the control values in 8-wk immobilized fibers (8.6 ± 0.7 nA, P = 0.48). In the presence of tetrodotoxin, the maximal residual sodium current decreased continuously throughout immobilization. Using the Western blot analysis, Nav1.4 expression showed a transient increase in 4-wk muscle, whereas Nav1.5 expression decreased during immobilization. Our results indicate that a muscle immobilized at optimal functional length with the preservation of neural inputs exhibits a transient fast phenotype conversion. Nav1.4 expression and current are related to the contractile phenotype variation.
Endothelial Microparticle Formation by Angiotensin II Is Mediated via Ang II Receptor Type I/NADPH Oxidase/ Rho Kinase Pathways Targeted to Lipid Rafts
Authors: Burger Dylan , Montezano Augusto C. , Nishigaki Nobuhiro , He Ying , Carter Anthony , Touyz Rhian M.
Published: May 2011

Objective—

Circulating microparticles are increased in cardiovascular disease and may themselves promote oxidative stress and inflammation. Molecular mechanisms underlying their formation and signaling are unclear. We investigated the role of reactive oxygen species (ROS), Rho kinase, and lipid rafts in microparticle formation and examined their functional significance in endothelial cells (ECs).

Methods and Results—

Microparticle formation from angiotensin II (Ang II)–stimulated ECs and apolipoprotein E
−/−
mice was assessed by annexin V or by CD144 staining and electron microscopy. Ang II promoted microparticle formation and increased EC

generation and Rho kinase activity. Ang II–stimulated effects were inhibited by irbesartan (Ang II receptor type I blocker) and fasudil (Rho kinase inhibitor). Methyl-β-cyclodextrin and nystatin, which disrupt lipid rafts/caveolae, blocked microparticle release. Functional responses, assessed in microparticle-stimulated ECs, revealed increased

production, enhanced vascular cell adhesion molecule/platelet-EC adhesion molecule expression, and augmented macrophage adhesion. Inhibition of epidermal growth factor receptor blocked the prooxidative and proinflammatory effects of microparticles. In vitro observations were confirmed in apolipoprotein E
−/−
mice, which displayed vascular inflammation and high levels of circulating endothelial microparticles, effects that were reduced by apocynin.

Conclusion—

We demonstrated direct actions of Ang II on endothelial microparticle release, mediated through NADPH oxidase, ROS, and Rho kinase targeted to lipid rafts. Microparticles themselves stimulated endothelial ROS formation and inflammatory responses. Our findings suggest a feedforward system whereby Ang II promotes EC injury through its own endothelial-derived microparticles.
Germinal Matrix Hemorrhage: Intraventricular Hemorrhage in Very-Low-Birth-Weight Infants
Authors: Ramenghi Luca A. , Fumagalli Monica , Groppo Michela , Consonni Dario , Gatti Loredana , Bertazzi Pier Alberto , Mannucci Pier Mannuccio , Mosca Fabio
Published: May 2011

Background and Purpose—

The etiology of germinal matrix hemorrhage–intraventricular hemorrhage (GMH-IVH) is multifactorial and the role of genetic polymorphisms is unclear. The aim of this prospective study was to evaluate prothrombotic genetic mutations as independent risk factors for the development of all grades of GMH-IVH in very-low-birth-weight infants.

Methods—

The presence of both factor V Leiden and prothrombin gain-of-function gene mutations were prospectively assessed in 106 very-low-birth-weight infants. Infants with GMH-IVH were compared to those without GMH-IVH according to genetic and clinical characteristics.

Results—

Twenty-two out of 106 infants had GMH-IVH develop (20.7%). Infants with GMH-IVH had significantly lower gestational ages and birth weights. In the multivariate Poisson regression model, the prevalence of GMH-IVH appeared to be inversely related to gestational age, with a risk ratio of 0.83 (95% CI, 0.72–0.97;
P
=0.02) per week. Risk ratio of GMH-IVH for carriers of either prothrombotic mutation was 2.65 (95% CI, 1.23–5.72;
P
=0.01), similar to the risk ratio associated with need for resuscitation at birth (2.30; 95% CI, 1.02–5.18;
P
=0.04).

Conclusions—

Very-low-birth-weight infants who are carriers for either prothrombotic mutations are at increased risk for development of GMH-IVH. Genetic factors act as independent risk factors of the same magnitude as other known risk factors.
Increased Brain Injury and Worsened Neurological Outcome in Interleukin-4 Knockout Mice After Transient Focal Cerebral Ischemia
Authors: Xiong Xiaoxing , Barreto George E. , Xu Lijun , Ouyang Yi Bing , Xie Xinmin , Giffard Rona G.
Published: May 2011

Background and Purpose—

Stroke causes brain injury with activation of an inflammatory response that can contribute to injury. We tested the hypothesis that the anti-inflammatory cytokine interleukin-4 (IL-4) reduces injury after stroke using IL-4 knockout (KO) adult male mice.

Methods—

IL-4 KO and wild-type mice were subjected to transient middle cerebral artery occlusion. Outcome was assessed by triphenyltetrazolium chloride staining for infarct volume, neuroscore and spontaneous activity for behavioral outcome, and immunostaining and stereological counting for cellular response.

Results—

Infarction volume at 24 hours was significantly larger in IL-4 KO mice, neurological score was significantly worse, and spontaneous activity was reduced compared with wild-type mice. Increased macrophage/microglial infiltration, increased numbers of myeloperoxidase-positive cells, and increased Th1/Th2 ratio were observed in the infarct core in IL-4 KO mice. Reduced astrocyte activation was observed in the cortical penumbra in IL-4 KO mice. Recombinant IL-4 administered intracerebroventricularly before middle cerebral artery occlusion significantly reduced infarct volume, improved neurological score, reduced macrophages/microglia, and lowered the Th1/Th2 ratio in IL-4 KO mice, but not in wild-type.

Conclusions—

Loss of IL-4 signaling in KO mice was associated with worse outcome, and this was reversed by giving exogenous IL-4. Worsened outcome was associated with increased inflammation in the core, which was reversed in IL-4 KO but not significantly changed in wild-type mice by exogenous IL-4. This is consistent with IL-4 signaling leading to reduced inflammation in the core and a possible beneficial role for activated astrocytes in the penumbra.
Intravenous Thrombolysis in Nonagenarians With Ischemic Stroke
Authors: Sarikaya Hakan , Arnold Marcel , Engelter Stefan T. , Lyrer Philippe A. , Michel Patrik , Odier Céline , Weder Bruno , Tettenborn Barbara , Mueller Felix , Sekoranja Lucka , Sztajzel Roman , Ballinari Pietro , Mattle Heinrich P. , Baumgartner Ralf W.
Published: May 2011

Background and Purpose—

Demographic changes will result in a rapid increase of patients age ≥90 years (nonagenarians), but little is known about outcomes in these patients after intravenous thrombolysis (IVT) for acute ischemic stroke. We aimed to assess safety and functional outcome in nonagenarians treated with IVT and to compare the outcomes with those of patients age 80 to 89 years (octogenarians).

Methods—

We analyzed prospectively collected data of 284 consecutive stroke patients age ≥80 years treated with IVT in 7 Swiss stroke units. Presenting characteristics, favorable outcome (modified Rankin scale [mRS] 0 or 1), mortality at 3 months, and symptomatic intracranial hemorrhage (SICH) using the National Institute of Neurological Disorders and Stroke (NINDS) and Safe Implementation of Thrombolysis in Stroke-Monitoring Study (SITS-MOST) criteria were compared between nonagenarians and octogenarians.

Results—

As compared with octogenarians (n=238; mean age, 83 years), nonagenarians (n=46; mean age, 92 years) were more often women (70% versus 54%;
P
=0.046) and had lower systolic blood pressure (161 mm Hg versus 172 mm Hg;
P
=0.035). Patients age ≥90 years less often had a favorable outcome and had a higher incidence of mortality than did patients age 80 to 89 years (14.3% versus 30.2%;
P
=0.034; and 45.2% versus 22.1%;
P
=0.002; respectively), while more nonagenarians than octogenarians experienced a SICH (SICH
NINDS
, 13.3% versus 5.9%;
P
=0.106; SICH
SITS-MOST
, 13.3% versus 4.7%;
P
=0.037). Multivariate adjustment identified age ≥90 years as an independent predictor of mortality (
P
=0.017).

Conclusions—

Our study suggests less favorable outcomes in nonagenarians as compared with octogenarians after IVT for ischemic stroke, and it demands a careful selection for treatment, unless randomized controlled trials yield more evidence for IVT in very old stroke patients.
Consequences of Stroke in Community-Dwelling Elderly
Authors: Divani Afshin A. , Majidi Shahram , Barrett Anna M. , Noorbaloochi Siamak , Luft Andreas R.
Published: May 2011

Background and Purpose—

Stroke survivors are at risk of developing comorbidities that further reduce their quality of life. The purpose of this study was to determine the risk of developing a secondary health problem after stroke.

Methods—

We performed a case–control analysis using 6 biennial interview waves (1998 to 2008) of the Health and Retirement Study. We compared 631 noninstitutionalized individuals who had a single stroke with 631 control subjects matched for age, gender, and interview wave. We studied sleep problems, urinary incontinence, motor impairment, falls, and memory deficits among the 2 groups.

Results—

Stroke survivors frequently developed new or worsened motor impairment (33%), sleep problems (up to 33%), falls (30%), urinary incontinence (19%), and memory deficits (9%). As compared with control subjects, the risk of developing a secondary health problem was highest for memory deficits (OR, 2.45; 95% CI, 1.34 to 4.46) followed by urinary incontinence (OR, 1.86; 95% CI, 1.31 to 2.66), motor impairment (OR, 1.61; 95% CI, 1.16 to 2.24), falls (OR, 1.5; 95% CI, 1.12 to 2.0), and sleep disturbances (OR, 1.49; 95% CI, 1.09 to 2.03). In contrast, stroke survivors were not more likely to injure themselves during a fall (OR, 1.14; 95% CI, 0.72 to 1.79). After adjusting for cardiovascular risk factors, social status, psychiatric symptoms, and pain, the risks of falling or developing sleep problems were not different from the control subjects.

Conclusions—

The risk of developing a secondary health problem that can impact daily life is markedly increased after stroke. A better understanding of frequencies and risks for secondary health problems after stroke is necessary for designing better preventive and rehabilitation strategies.
Population and Railways in Portugal, 1801–1930
Authors: da Silveira Luís Espinha , Alves Daniel , Lima Nuno Miguel , Alcântara Ana , Puig Josep
Published: May 2011

Portuguese historiography has mostly adopted a pessimistic view regarding the contribution of the railways to the development of country. Yet, railway access helped to increase population concentration and economic development, favoring migration into towns, the growth of pre-existing urban centers, and the emergence of new centers. But railways tended to be more beneficial to regions that were already prosperous and to aggravate the conditions unfavorable to development in areas with greater structural weaknesses.
Spatial History: Railways, Uneven Development, and Population Change in France and Great Britain, 1850–1914
Authors: Schwartz Robert , Gregory Ian , Thévenin Thomas
Published: May 2011

A comparative spatial history combining historical narrative, geographical thinking, and spatial analysis of historical data offers new perspectives on railway expansion and its effects in France and Great Britain during the long nineteenth century. Accessible rail transport in the rural regions of both countries opened new economic opportunities in agriculture, extractive industries, and service trades, helping to revitalize rural communities and decrease their rates of out-migration. In France, long-standing economic disparities between the developed north and the less-productive south gradually reduced. These conclusions are based, in part, on the use of historical geographical information systems (hgis) and spatial statistics, illustrating a component of spatial history.
The Effect of Railway Expansion on Population in Turkey, 1856–2000
Authors: Akgüngör Sedef , Aldemir Ceyhan , Kuştepeli Yeşim , Gülcan Yaprak , Tecim Vahap
Published: May 2011

The development of Turkey's railway network started in 1856 with the 130 km İzmir-Aydjn line. Turkey's total railway network now measures 11,005 km. The population distribution and the density of towns on railway routes increased as railway construction proliferated, particularly from 1856 to 1940. Public policies that favored transportation by road after the mid-twentieth century, however, marked the end of the railroad's effect on the spread of population.
Transient Possessions: Circulation, Replication, and Transmission of Gems and Jewels in Quattrocento Italy
Authors: Clark Leah R.
Published: May 2011

This article examines the circulation of gems, jewelry, and antique hardstones, through merchant-banking networks in Italy in the late Quattrocento. The practices of pawning and exchange facilitated the circulation of objects, causing those goods to change hands constantly and to come into contact with a wide range of individuals, a process through which these artifacts accrued histories. Particular gems were sought after, not only for their material or artistic worth, but also for their histories and their previous illustrious owners, and many jewels were invested with names. Aside from their physical circulation, these objects were disseminated in visual form through replication across media, which raises questions around ownership, copies, and collections in the late fifteenth century.
How NGOs Advance Corporate Social Responsibility in China
Authors: Jia’ning Yang , Chan Kin-man
Published: May 2011

On the basis of four NGO case studies, this article considers how NGOs promote corporate social responsibility (CSR) from the angle of resource mobilization. NGOs’ approaches to promoting CSR can be divided into three types: cooperative, independent, and oppositional. Within the cooperative approach, there are two types of relationships between NGOs and enterprises. In the first, “integrated” social enterprise approach, NGO and enterprises are highly codependent. In the second, the NGO cooperates as an entity external to the enterprise. The independent approach has the NGO acting as a third-party examiner, and, based on its cooperation with a famous international organization, performing CSR evaluation and training for Mainland processing enterprises. The oppositional approach consists of NGOs using social movements to cast light on whether or not enterprises are fulfilling their social responsibilities. NGOs’ different levels of resources determine the power dynamics between them and enterprises. Those different power dynamics, in turn, determine the methods and strategies NGOs will use to try to compel enterprises to take on social responsibility and determine the kinds of relationships that form. These different approaches also reflect that NGOs lack institutional protections for their efforts to stimulate CSR. Currently, their efforts to advance CSR have not yet been able to develop into institutionally diverse models.
A Survey of NGO Participation in Reconstruction after the Wenchuan Earthquake: The Social Work Perspective
Authors: Kenan Wei , Qiongwen Zhang , Hua Feng
Published: May 2011

After the Wenchuan earthquake, large numbers of NGOs entered the quake area and provided large amounts of social services. Analysis of survey responses from 149 NGOs has allowed three basic models to be identified among NGOs engaging in post-quake reconstruction: (1) university social work stations; (2) civil organizations; and (3) government-embedded organizations. Because reconstruction is a long-term task, adjustments to current strategies may merit consideration. First, the disproportionate weight currently placed on heavy infrastructure over social services and society-building must be rebalanced. Second, all of society ‐ and especially the government ‐ should recognize the enormous significance and the enormous role NGO services have played in post-quake reconstruction. Third, cooperative arrangements should be explored between grant makers like the government, enterprises, and foundations and NGOs. Fourth, trial introduction of people-run non-enterprise units to the quake area should be explored. Fifth, relations between NGOs and the government should be smoothed to ensure that NGOs have a legal space in which to conduct their social work. Sixth, NGOs must put more work into capacity building.
Dr. Astrov: Chekov's Notable Idealist
Authors: Polakiewicz Leonard A.
Published: May 2011

Chekhov depicted a number of idealists – individuals whose behavior and thought is based on ideals that for the most part prove to be impractical or unattainable in reality. These noble visionaries have a conception of things as they wish them to be. Many of Chekhov's idealists are doctors who, more often than not, suffer defeat on a personal rather than on a professional level. Dr. Astrov appears to suffer a defeat both on a personal level and in some respects on a professional level. The present study aims to provide an analysis of the nature of Dr. Astrov's idealism, his struggle with existential obstacles, and his personal and professional struggle against the complex forces that challenge his idealism and eventually turn him into a cynic.