bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study of Digitally Controllable Radio Frequency Micro Electro Mechanical Systems Inductor
Authors: Shirane Atsushi , Mizuochi Yutaka , Amakawa Shuhei , Ishihara Noboru , Masu Kazuya
Published: May 2011

This work proposes a micro electro mechanical systems (MEMS)-based digitally controlled solenoid-inductor. The inductor is fabricated by using a MEMS process. 2-bit tuning characteristics are measured, and tuning linearity and Q-factor degradation due to switching loss are discussed. The linear inductance tuning from 1.7 to 2.2 nH was achieved at 2 GHz. A Q-factor of more than ten was observed in the frequency range of 1.2 to 7.4 GHz. The validity of the proposed inductor was confirmed by investigating the effect of switch resistance.
Improvement in Electrical Properties of Carbon Nanotube Via Interconnects
Authors: Katagiri Masayuki , Yamazaki Yuichi , Wada Makoto , Kitamura Masayuki , Sakuma Naoshi , Suzuki Mariko , Sato Shintaro , Nihei Mizuhisa , Kajita Akihiro , Sakai Tadashi , Awano Yuji
Published: May 2011

We report on the electrical properties of carbon nanotube (CNT) via interconnects with improvement in contact formations between the CNT via and metal electrodes. For the improvement of the bottom contact formation, a TiN/TaN multilayer on a Cu bottom wiring layer is applied to suppress formation of a highly resistive oxide layer on the TaN barrier layer. The top electrode formation with good coverage on CNTs reduces contact resistance. The current–voltage characteristics of ultrafine CNT via interconnects exhibit ohmic behavior. The resistance of the CNT via interconnect is inversely proportional to the via area, indicating that the CNT bundles are grown with uniform quality and density in various-diameter via holes.
Chemical Vapor Deposition of Nanocarbon on Electroless NiB Catalyst Using Ethanol Precursor
Authors: Tanaka Toru , Sato Tomomi , Karasawa Yusuke , Ueno Kazuyoshi
Published: May 2011

Nanocarbon materials have been expected as post-Cu interconnect materials for large-scale integrated circuits (LSIs). In this paper, we present a nanocarbon deposition process using electroless plated NiB as the catalyst, which features conformal deposition on patterned dielectric surfaces. It was found that carbon nanotubes (CNTs) and graphitic films were deposited on the electroless NiB by atmospheric pressure chemical vapor deposition (CVD) using ethanol as the precursor. The graphitic quality estimated from the Raman spectra of the nanocarbon on the NiB catalyst was equivalent to that on a sputter-deposited pure Ni catalyst. The nanocarbon shape was dependent on NiB thickness, and CNTs were grown on 10-nm-thick NiB and graphitic films were grown on 30 nm or thicker NiB. The deposition temperature can be lowered to 505 °C, although the graphitic quality was degraded. It is considered that the electroless catalysts can be effective for nanocarbon deposition on patterned dielectric surfaces.
Iridium Nanocrystal Thin-Film Transistor Nonvolatile Memory with Si3N4/SiO2 Stack of Asymmetric Tunnel Barrier
Authors: Wang Terry Tai-Jui , Lu Tien-Lin , Wu Chien-Hung , Liu Yu-Cheng , Hung Shih-Wei , Hsieh Ing-Jar , Kuo Cheng-Tzu
Published: May 2011

Iridium nanocrystals (Ir-NCs) lying on the Si3N4/SiO2 tunneling layer have been demonstrated and Ir-NC-assisted thin-film transistor nonvolatile memory devices were successfully developed. Results show that Ir-NCs with a number density of ∼6×1011 cm-2 and a particle diameter of 4 to 12 nm can successfully be fabricated as charge trapping centers. Owing to the asymmetric SiO2/Si3N4 tunneling layer that increases programming/erasing efficiency, a significant memory window of 5.5 V has potential to be applied to multibit memory devices. Furthermore, after 104 s, the memory window is still about 4.0 V in logic states.
Epitaxial Growth of Chalcopyrite-Type CuInS2 Films on GaAs(001) Substrates by Evaporation Method with Elemental Sources
Authors: Tsuboi Nozomu , Tamogami Takashi , Kobayashi Satoshi
Published: May 2011

The structural properties of epitaxial CuInS2 thin films with various [Cu]/[In] ratios grown on GaAs(001) by the co-evaporation method with three element-sources are reported in comparison to those of the films on GaP(001). For the In-rich and almost stoichiometric films, the CuIn5S8 phase and metastable CuAu-type ordering of the CuInS2 phase were exhibited. The Cu-rich films had sphalerite-type ordering of the CuInS2 phase. The slightly Cu-rich films had the c-axis oriented chalcopyrite-type CuInS2 structure with traces of the CuAu-type ordering and twins. Taking account of the fact that the slightly Cu-rich films on GaP had only the c-axis oriented chalcopyrite-type structure, the traces are considered to be due to the larger lattice mismatch for GaAs than for GaP. Broad photoluminescence emission bands in the band-edge region of the films, which could be related to shallow levels, were observed at low temperature.
Initial Growth Process in Electrochemical Deposition of ZnO
Authors: Ashida Atsushi , Nouzu Naoya , Fujimura Norifumi
Published: May 2011

ZnO thin films were prepared by electrochemical deposition on (111)Pt/c-sapphire from zinc nitrate aqueous solution by supplying constant current. All films were epitaxially grown, but with a wide distribution of in-plane orientation. For several tens of seconds after the start of the deposition, the time course of cathodic potential showed positive potential versus Ag/AgCl, which is out of range for ZnO growth. Then, the potential decreased abruptly to a negative value and remained constant in the growth range. To evaluate the initial crystal growth, the deposition was stopped immediately after the decrease in potential and the resultant film was characterized by reflective high-energy electron diffraction analysis. The sample was found to contain Zn(OH)2; therefore, the distribution of the in-plane orientation of the ZnO films is considered to arise from this initial growth of Zn(OH)2.
Evaluation of Composition Reproducibility of HgCdTe Epitaxial Layers Grown in Novel Liquid Phase Epitaxy Apparatus
Authors: Huseynov Emil , Eminov Shikhamir , Rajabli Alovsat , Ibragimov Tarlan
Published: May 2011

The results of Hg1-x
Cd
x
Te layer growth by liquid phase epitaxy (LPE) from the Te-rich solution (Hg1-z
Cd
z
)1-y
Te
y
with z=0.0545 and y=0.806 obtained by the tipping method in a closed system are presented. The epitaxial layers with different compositions, x=0.20–0.22, and thicknesses ranging from 10 to 20 µm, which are suitable for manufacturing IR photodiode structures, were grown on (111) B-oriented Cd0.96Zn0,04Te substrates at 501–470 °C in a sealed quartz ampoule. A novel LPE apparatus for obtaining of a residual-melt-drop-free surface is described. The effect of the preliminary synthesis of the source on the reproducibility of both the liquidus temperature (ΔΘ±1.8 °C) and epilayer composition (Δx±0.003) was evaluated using the expression for the Hg–Cd–Te phase diagram. As-grown layers exhibit p-type conductivity with a carrier concentration in the range from 4×1016 to 1.4×1017 cm-3 and mobility of 240–270 cm2 V-1 s-1. The concentration and mobility of charge carriers in the layers annealed at 280 °C for 10 h under Hg overpressure were found to be 5×1015 cm-3 and 1×104 cm2 V-1 s-1, respectively.
Photoluminescence Study of AgInS2 by Using Confocal Microscopy System
Authors: Miyamoto Umihito , Sizuki Akinori , Honjo Kazuhiro , Shim YongGu , Tokuda Takahiro , Yoshino Kenji , Mamedov Nazim , Wakita Kazuki
Published: May 2011

The photoluminescence (PL) spectra of AgInS2 crystals grown by a hot-press method have been investigated by confocal microspectroscopy. The two-dimensional image of PL intensity, which shows an area of the chalcopyrite and orthorhombic structures, with a high resolution of micrometer order was obtained. The free-exciton and biexciton emissions on the chalcopyrite structure were clearly separated. Furthermore, the temperature dependence of band-gap energy was analyzed.
Peculiar Linear Dispersive Bands Observed in Angle-Resolved Photoemission Spectra of Tl-Based Ternary Chalcogenide TlGaTe2
Authors: Mimura Kojiro , Ishizu Takahiko , Motonami Satoru , Wakita Kazuki , Arita Masashi , Hamidov Sadig , Chahangirli Zakir , Taguchi Yukihiro , Namatame Hirofumi , Taniguchi Masaki , Orudzhev Guseyn , Mamedov Nazim
Published: May 2011

Electronic energy bands of the Tl-based ternary chalcogenide TlGaTe2 with a quasi one-dimensional crystalline structure have been studied by means of high resolution angle-resolved photoemission spectroscopy (ARPES) in order to check for dispersive structures similar to the Dirac cone observed in the surface bands of Bi-based binary chalcogenides. Two linear dispersive structures which are not reproduced in band calculations for bulk material have been observed in the energy band along the Γ–N direction perpendicular to the chains. These dispersions form a cross-type structure that is centered at the Γ point and extends along the Γ–H–T direction parallel to the chains, reflecting, in our opinion, one-dimensional features of surface morphology of TlGaTe2. The cross-type structure, the energy position of which linearly varies with excitation photon energy, is observed only for high-grade quality surfaces of TlGaTe2. It is therefore assumed that the observed peculiar dispersive structure is caused by the Dirac-type dispersion of high-lying surface conduction bands and that ARPES detects the joint density of states.
Spectroscopic Ellipsometry Studies of CdS:O Layers for Solar Cells
Authors: Shim Yong-Gu , Sakamoto Junichi , Suzuki Akinori , Khalilova Khuraman , Wakita Kazuki , Mamedov Nazim , Bayramov Ayaz , Huseynov Emil , Hasanov Ilham
Published: May 2011

This work reports the results of spectroscopic ellipsometry study of CdS thin films, deposited on glass substrates in the presence of oxygen at room temperature by rf sputtering. The data acquisition, together with the subsequent linear regression analysis to restore dielectric function has been performed over the photon energy range 1.5–5.0 eV. The obtained oxygen-free CdS films and reference bulk CdS have been found to be very much the same regarding their dielectric function spectra. On the other hand, blue-shift of the main structures in dielectric function has been observed for CdS:O films deposited at 5% value of O/Ar ratio. In spite of the broadening taking place on a par with the shift, the last turns out to be so large that provides transparency of CdS:O thin films in a spectral range above the energy gap of CdS. The obtained results allow to considering CdS:O as an improved window-layer material for solar cell application.
Temperature-Induced Valence Transition of EuPd2Si2Studied by Hard X-ray Photoelectron Spectroscopy
Authors: Mimura Kojiro , Uozumi Takayuki , Ishizu Takahiko , Motonami Satoru , Sato Hitoshi , Utsumi Yuki , Ueda Shigenori , Mitsuda Akihiro , Shimada Kenya , Taguchi Yukihiro , Yamashita Yoshiyuki , Yoshikawa Hideki , Namatame Hirofumi , Taniguchi Masaki , Kobayashi Keisuke
Published: May 2011

We have studied the electronic structure of EuPd2Si2by hard X-ray photoelectron spectroscopy (HX-PES) from 300 to 20 K. The temperature-dependent HX-PES spectra clearly show the valence transition, namely, the intensities of the divalent and trivalent Eu 3d components are abruptly changed. The change in Eu 3d spectral shape, especially the drastic change in the trivalent Eu 3d feature with temperature, can be explained within the framework of the Anderson model. The peak shift of Pd 3d core level with temperature indicates that the valence electrons of Pd contribute to the temperature-induced valence transition of EuPd2Si2.
Metal–Insulator Transition Induced by Temperature in Bi2Te3-xClx Layered Compound
Authors: Abdullayev Nadir A. , Abdullayev Nadir M. , Aliguliyeva Xayala V. , Gahramanov Samir Sh. , Kerimova Taira G. , Mustafayeva Konul M. , Nemov Sergey A. , Zverev Vladimir N.
Published: May 2011

It is shown, that doping by chlorine atoms changes the type of conductivity of Bi2Te3 from p- to n-type as well as the character of conductivity. In the direction perpendicular to the layers plane phonon assisted hopping conductivity is observed. The mechanism of charge transport in Bi2Te3 crystals doped by chlorine atoms is proposed.
Ab initio Calculations of Elastic Constants of Superalloys
Authors: Isaev Eyvaz I. , Ponomareva Alena V. , Bleskov Ivan D. , Vekilov Yuri Kh.
Published: May 2011

Using the-state-of-the-art ab initio method we have studied elastic constants of alloys potentially interesting for high temperature applications. We have shown that Cr substitutes the Al sublattice in B2 NiAl at concentration up to 40 at. %, but at higher Cr content it prefers the Ni-sublattice. Alloying of NiAl with Cr yields reduced strength but improves the ductility of the alloys. Alloying of NiAl with W which substitutes the Al sublattice, leads to a strong decrease of the shear modulus, and near 50 at. % of W the alloy becomes mechanically unstable as elastic constant C' is negative. This is in agreement with our phonon calculations where we found soft modes along the [110] direction for B2 NiW. According to our calculations in (Ru,Ni)Al alloys the shear modulus is almost constant up to 40 at. % of Ni, at higher Ni concentrations it is drastically reduced. We have shown that the changes in elastic properties of (Ru–X)Al alloys are due to electronic topological transitions.
The Phonon Percolation Scheme for Alloys: Extension to the Entire Lattice Dynamics and Pressure Dependence
Authors: Pradhan Gopal Krushna , Narayana Chandrabhas , Rao Mala Narasappaya , D'Astuto Matteo , Chaplot Samrath Lal , Pagès Olivier , Breidi A. , Souhabi Jihane , Postnikov Andrei , Deb Sudip Kumar , Ganguli Tapas , Polian Alain , Bhalerao Gopalkrishna , Shukla Abhay , Firszt Franciszek , Paszkowicz Wojciech
Published: May 2011

We explore two basic issues behind the 1-bond → 2-mode percolation scheme that has recently lead to a unification of the classification of the Raman and infrared spectra of usual zincblende semiconductor alloys. In doing so we focus on the model ZnBeSe alloy, for which the percolation scheme was originally developed. First, we show by using inelastic neutron scattering that the well-resolved 1-bond → 2-mode percolation doublet of the short Be–Se bond detected close to the zone center by Raman and infrared spectra remains observable throughout the whole Brillouin zone up to the zone edge. This testifies for an origin at the bond scale. Second, high-pressure is used to disable a Fano interference which screens the Zn–Se Raman signal, revealing a distinct Zn–Se percolation doublet. This provides experimental evidence that the 1-bond → 2-mode percolation scheme is generic, and may, in principle, apply to all bonds in an alloy.
Structural, Optical, and Electrical Properties of Semiconductor Compounds Studied by Means of Inelastic Light Scattering from Phonon, Electron, and Coupled Electron–Phonon Excitations: From Bulk to Nanoscale Structures
Authors: Bayramov Farid H. , Irmer Gert , Toporov Vladimir V. , Bairamov Bakhysh H.
Published: May 2011

We show results of our systematic investigation by means of quasi-elastic and inelastic laser light scattering (QEILS) of electron- and hole–phonon interactions as well as charge- and spin-density scattering mechanisms from hole gas fluctuations including their overlapping with phonon features by using near infrared excitation of doped bulk p-GaAs and self-assembled InAs/GaAs quantum dot (QD) structures. Additionally, results of our study of CdS and CdSe/ZnS QDs, multi-functionalized by peptides possessing strict affinity to integrins of MDA-MB-435 cancer cells are also presented.
Multiscale Simulation of Nanostructured Materials and Systems
Authors: Nelayev Vladislav , Barkaline Viatcheslav , Brechko Teodor , Chashynski Alexander , Lyskovski Viachaslau , Mamedov Nazim
Published: May 2011

A hierarchical approach to simulation of nanostructured materials and systems is discussed by examples of ab initio calculations of the strain dependence of electronic properties of TlMeX2 compounds (Me = In, Ga, Tl; X = S, Se, Te) and study of sensitivity of ordered carbon nanotube (CNT) array based acoustic gas sensors.
Switching of Multiples Solitons in Arrays of Coupled Cavities
Authors: Aghdami Keivan M. , Kheradmand Reza , Karimi Roghayyeh
Published: May 2011

In this paper, light propagation dynamics in a coupled optical cavities array in self-defocusing configuration which has been driven by a holding beam is investigated numerically. It was shown that superposition of appropriate Gaussian control beam and plane wave holding beam can be used to write and erase of discrete cavity solitons and to switch between different orders of solitons. This method develops as an important issue of light control and all optical switches.
Switching On/Off of Cavity Solitons in Semiconductor Microresonators via Carrier Injection above Laser Threshold
Authors: Kheradmand Reza , Eslami Mansour
Published: May 2011

We studied the cavity solitons (CSs) and their switching in a semiconductor Fabry–Perot type microresonator where the active medium is multiple quantum well nanostructures. We take benefit of the full set of Maxwell–Bloch equations to describe the dynamical behavior of the system, since the rate equation model for a two-level system fails to explain the system when considering femtosecond time scales. Numerical simulations imply formation of stable CSs which is done by local carrier injection as the switching method. To switch off these CSs we used the same method but with negative amplitude of the injection function. It is also realized that the successive switching on/off of CSs by such a scheme is possible in this system.
Sulfurization Growth of SnS Thin Films and Experimental Determination of Valence Band Discontinuity for SnS-Related Solar Cells
Authors: Sugiyama Mutsumi , Murata Yoshitsuna , Shimizu Tsubasa , Ramya Kottadi , Venkataiah Chinna , Sato Tomoaki , Reddy K. T. Ramakrishna
Published: May 2011

Tin sulphide is considered to be a potential candidate for the development of low cost polycrystalline thin film solar cells. The advantages of using sulfurization process to grow SnS films were demonstrated. Polycrystalline p-type SnS films were obtained by a simple dry process at 300 °C for 90 min. The sulfurization condition depends on the deposition method of the Sn precursor. Using single-phase SnS films, band discontinuities at SnS/CdS and SnO2/SnS heterointerfaces were measured by X-ray photoelectron spectroscopy. The valence band offsets were determined to be approximately 1.5 eV for SnS/CdS and 3.5 eV for SnO2/SnS interfaces. Using these values and the energy band gaps of the corresponding layers, the energy band diagram was developed. It indicated that the SnS/CdS heterojunction is of TYPE-II form of heterostructure. This result indicated that SnS-related solar cells with CdS as window layer do not have an ideal band structure that could give high conversion efficiency.
Single-Phase Cadmium Telluride Thin Films Deposited by Electroless Electrodeposition
Authors: Khrypunov Gennadiy , Klochko Natalja , Volkova Neonila , Lyubov Viktor , Li Tatyana
Published: May 2011

By means of analysis of electrochemical processes taking place during electroless electrodeposition have elaborate method for obtaining of well adherent smooth and stoichiometric single-phase CdTe films with cubic structure. Illumination of the growing layers has increased their thickness and improved film crystallinity. Following improvement of CdTe structure was riched by “chloride treatment” of the films. So, the novel electroless electrodeposition technique gives possibilities for the manufacture of CdTe absorbers suitable for η-solar cells.
Reflectance Profile of BaTiO3 on Multilayer Antireflection Coating Systems
Authors: Karaomerlioglu Filiz
Published: May 2011

Antireflection (AR) coating systems are very important technology for optoelectronic devices. The optical characteristics of the system can be regulated by external electric or thermal field, and designed broadband ultra low reflection coating systems. It is investigated optical properties of multilayer AR coatings based on different ferroelectric materials to reduce reflectance in other studies. In this study, reflectance profile of BaTiO3 on multilayer AR coating systems has been developed in the visible region. It has been used ZnSe and ZrO2 as multilayer AR coatings, and BaTiO3 as the substrate. Fortran program has been simulated on Fresnell equations base.
Thrombosis, physical activity, and acute coronary syndromes
Authors: Kumar Arun , Kar Subrata , Fay William P.
Published: May 2011

Acute coronary syndromes (ACS) are common, life-threatening cardiac disorders that typically are triggered by rupture or erosion of an atherosclerotic plaque. Platelet deposition and activation of the blood coagulation cascade in response to plaque disruption lead to the formation of a platelet-fibrin thrombus, which can grow rapidly, obstruct coronary blood flow, and cause myocardial ischemia and/or infarction. Several clinical studies have examined the relationship between physical activity and ACS, and numerous preclinical and clinical studies have examined specific effects of sustained physical training and acute physical activity on atherosclerotic plaque rupture, platelet function, and formation and clearance of intravascular fibrin. This article reviews the available literature regarding the role of physical activity in determining the incidence of atherosclerotic plaque rupture and the pace and extent of thrombus formation after plaque rupture.
Neuromuscular adjustments that constrain submaximal EMG amplitude at task failure of sustained isometric contractions
Authors: Dideriksen Jakob L. , Enoka Roger M. , Farina Dario
Published: May 2011

The amplitude of the surface EMG does not reach the level achieved during a maximal voluntary contraction force at the end of a sustained, submaximal contraction, despite near-maximal levels of voluntary effort. The depression of EMG amplitude may be explained by several neural and muscular adjustments during fatiguing contractions, including decreased net neural drive to the muscle, changes in the shape of the motor unit action potentials, and EMG amplitude cancellation. The changes in these parameters for the entire motor unit pool, however, cannot be measured experimentally. The present study used a computational model to simulate the adjustments during sustained isometric contractions and thereby determine the relative importance of these factors in explaining the submaximal levels of EMG amplitude at task failure. The simulation results indicated that the amount of amplitude cancellation in the simulated EMG (∼40%) exhibited a negligible change during the fatiguing contractions. Instead, the main determinant of the submaximal EMG amplitude at task failure was a decrease in muscle activation (number of muscle fiber action potentials), due to a reduction in the net synaptic input to motor neurons, with a lesser contribution from changes in the shape of the motor unit action potentials. Despite the association between the submaximal EMG amplitude and reduced muscle activation, the deficit in EMG amplitude at task failure was not consistently associated with the decrease in neural drive (number of motor unit action potentials) to the muscle. This indicates that the EMG amplitude cannot be used as an index of neural drive.
Ca2+ regulatory mechanisms of exercise protection against coronary artery disease in metabolic syndrome and diabetes
Authors: Sturek Michael
Published: May 2011

Chronic exercise attenuates coronary artery disease (CAD) in humans largely independent of reductions in risk factors; thus major protective mechanisms of exercise are directly within the coronary vasculature. Further, tight control of diabetes, e.g., blood glucose, can be detrimental. Accordingly, knowledge of mechanisms by which exercise attenuates diabetic CAD could catalyze development of molecular therapies. Exercise attenuates CAD (atherosclerosis) and restenosis in miniature swine models, which enable precise control of exercise parameters (intensity, duration, and frequency) and characterization of the metabolic syndrome (MetS) and diabetic milieu. Intracellular Ca2+ is a pivotal second messenger for coronary smooth muscle (CSM) excitation-contraction and excitation-transcription coupling that modulates CSM proliferation, migration, and calcification. CSM of diabetic dyslipidemic Yucatan swine have impaired Ca2+ extrusion via the plasmalemma Ca2+ ATPase (PMCA), downregulation of L-type voltage-gated Ca2+ channels (VGCC), increased Ca2+ sequestration by the sarcoplasmic reticulum (SR) Ca2+ ATPase (SERCA), increased nuclear Ca2+ localization, and greater activation of K channels by Ca2+ release from the SR. Endurance exercise training prevents Ca2+ transport changes with virtually no effect on the diabetic milieu (glucose, lipids). In MetS Ossabaw swine transient receptor potential canonical (TRPC) channels are upregulated and exercise training reverses expression and TRPC-mediated Ca2+ influx with almost no change in the MetS milieu. Overall, exercise effects on Ca2+ signaling modulate CSM phenotype. Future studies should 1) selectively target key Ca2+ transporters to determine definitively their causal role in atherosclerosis and 2) combine mechanistic studies with clinical outcomes, e.g., reduction of myocardial infarction.
High sodium chloride intake exacerbates immobilization-induced bone resorption and protein losses
Authors: Frings-Meuthen Petra , Buehlmeier Judith , Baecker Natalie , Stehle Peter , Fimmers Rolf , May Francisca , Kluge Goetz , Heer Martina
Published: May 2011

We examined, in immobilization, the effect of a diet high in sodium chloride (NaCl) on bone markers, nitrogen balance, and acid-base status. Eight healthy male test subjects participated in a 14-day head-down-tilt bed rest (HDBR) study. During the bed rest period they received, in a randomized crossover design, a high (7.7 meq Na+/kg body wt per day) and a low (0.7 meq Na+/kg body wt per day) NaCl diet. As expected, 24-h excretion of urinary calcium was significantly greater in the high-NaCl-intake HDBR phase than in the low-NaCl-intake HDBR phase ( P < 0.001). High NaCl intake caused a 43–50% greater excretion of the bone resorption markers COOH- (CTX) and NH2- (NTX) terminal telopeptide of type I collagen in HDBR than low NaCl in HDBR (CTX/NTX: P < 0.001). Serum concentrations of the bone formation markers bone-specific alkaline phosphatase (bAP) and NH2-terminal propeptide of type I procollagen (PINP) were identical in both NaCl intake phases. High NaCl intake led to a more negative nitrogen balance in HDBR ( P < 0.001). Changes were accompanied by increased serum chloride concentration ( P = 0.008), reduced blood bicarbonate ( P = 0.017), and base excess ( P = 0.009) whereas net acid excretion was lower during high than during low NaCl intake in immobilization ( P < 0.001). High NaCl intake during immobilization exacerbates disuse-induced bone and muscle loss by causing further protein wasting and an increase in bone resorption. Changes in the acid-base status, mainly caused by disturbances in electrolyte metabolism, seem to determine NaCl-induced degradation processes.
The relationship between human skeletal muscle pyruvate dehydrogenase phosphatase activity and muscle aerobic capacity
Authors: Love Lorenzo K. , LeBlanc Paul J. , Inglis J. Greig , Bradley Nicolette S. , Choptiany Jon , Heigenhauser George J. F. , Peters Sandra J.
Published: May 2011

Pyruvate dehydrogenase (PDH) is a mitochondrial enzyme responsible for regulating the conversion of pyruvate to acetyl-CoA for use in the tricarboxylic acid cycle. PDH is regulated through phosphorylation and inactivation by PDH kinase (PDK) and dephosphorylation and activation by PDH phosphatase (PDP). The effect of endurance training on PDK in humans has been investigated; however, to date no study has examined the effect of endurance training on PDP in humans. Therefore, the purpose of this study was to examine differences in PDP activity and PDP1 protein content in human skeletal muscle across a range of muscle aerobic capacities. This association is important as higher PDP activity and protein content will allow for increased activation of PDH, and carbohydrate oxidation. The main findings of this study were that 1) PDP activity ( r2= 0.399, P = 0.001) and PDP1 protein expression ( r2= 0.153, P = 0.039) were positively correlated with citrate synthase (CS) activity as a marker for muscle aerobic capacity; 2) E1α ( r2= 0.310, P = 0.002) and PDK2 protein ( r2= 0.229, P =0.012) are positively correlated with muscle CS activity; and 3) although it is the most abundant isoform, PDP1 protein content only explained ∼18% of the variance in PDP activity ( r2= 0.184, P = 0.033). In addition, PDP1 in combination with E1α explained ∼38% of the variance in PDP activity ( r2= 0.383, P = 0.005), suggesting that there may be alternative regulatory mechanisms of this enzyme other than protein content. These data suggest that with higher muscle aerobic capacity (CS activity) there is a greater capacity for carbohydrate oxidation (E1α), in concert with higher potential for PDH activation (PDP activity).
Changes of calf muscle-tendon biomechanical properties induced by passive-stretching and active-movement training in children with cerebral palsy
Authors: Zhao Heng , Wu Yi-Ning , Hwang Miriam , Ren Yupeng , Gao Fan , Gaebler-Spira Deborah , Zhang Li-Qun
Published: May 2011

Biomechanical properties of calf muscles and Achilles tendon may be altered considerably in children with cerebral palsy (CP), contributing to childhood disability. It is unclear how muscle fascicles and tendon respond to rehabilitation and contribute to improvement of ankle-joint properties. Biomechanical properties of the calf muscle fascicles of both gastrocnemius medialis (GM) and soleus (SOL), including the fascicle length and pennation angle in seven children with CP, were evaluated using ultrasonography combined with biomechanical measurements before and after a 6-wk treatment of passive-stretching and active-movement training. The passive force contributions from the GM and SOL muscles were separated using flexed and extended knee positions, and fascicular stiffness was calculated based on the fascicular force-length relation. Biomechanical properties of the Achilles tendon, including resting length, cross-sectional area, and stiffness, were also evaluated. The 6-wk training induced elongation of muscle fascicles (SOL: 8%, P = 0.018; GM: 3%, P = 0.018), reduced pennation angle (SOL: 10%, P = 0.028; GM: 5%, P = 0.028), reduced fascicular stiffness (SOL: 17%, P = 0.128; GM: 21%, P = 0.018), decreased tendon length (6%, P = 0.018), increased Achilles tendon stiffness (32%, P = 0.018), and increased Young's modulus (20%, P = 0.018). In vivo characterizations of calf muscles and Achilles tendon mechanical properties help us better understand treatment-induced changes of calf muscle-tendon and facilitate development of more effective treatments.
Silencing IL-13Rα2 Promotes Glioblastoma Cell Death via Endogenous Signaling
Authors: Hsi Linda C. , Kundu Suman , Palomo Juan , Xu Bo , Ficco Ryan , Vogelbaum Michael A. , Cathcart Martha K.
Published: May 2011

Glioblastoma multiforme (GBM) is one of the most lethal forms of cancer, with a survival rate of only 13% to 27% within 2 years of diagnosis despite optimal medical treatment. We hypothesize that the presence of a unique IL-13Rα2 decoy receptor prevents GBM apoptosis. This receptor has a high affinity for interleukin-13 (IL-13), binds the cytokine, and competitively inhibits the intracellular signaling cascade initiated by IL-13. In cells lacking the IL-13Rα2 decoy receptor, IL-13 initiates the production of 15-lipoxygenase-1 (15-LOX-1), which has been implicated in cellular apoptosis. Our group and others have shown that induction of 15-LOX-1 correlates with tumor cell death in colorectal, pancreatic, and prostate cancer. How 15-LOX-1 induces apoptosis remains unclear. Preliminary evidence in GBM cells implicates an apoptotic process mediated by PPARγ. 15-LOX-1 metabolites can modulate PPARγ and activation of PPARγ can suppress tumor growth. We hypothesize that in GBM, IL-13 can induce 15-LOX-1, which regulates cell apoptosis via signaling through PPARγ and that expression of IL-13Rα2 prevents apoptosis and contributes to tumor growth. Our in vitro and in vivo data support this. Knocking down IL-13Rα2 with short interfering RNA dramatically induces 15-LOX-1 expression, promotes apoptosis, and reduces GBM tumor growth in vivo. These findings identify a mechanism for eliminating the blockade of endogenous IL-13 signaling and for promotion of apoptosis, and characterize a role for 15-LOX-1 in GBM apoptosis. Identifying a mechanistic pathway that can be targeted for pharmacologic intervention will have applied implications to developing novel and effective treatments of GBM. Mol Cancer Ther; 10(7); 1149–60. ©2011 AACR.
Runx2 Regulates the Gene Network Associated with Insulin Signaling and Energy Homeostasis
Authors: Adhami Mitra , Ghori-Javed Farah Y. , Chen Haiyan , Gutierrez Soraya E. , Javed Amjad
Published: May 2011

Glucose intolerance seen in metabolic disorders, such as type II diabetes, is commonly associated with improper execution of the insulin signaling pathway, as well as an imbalance of bone and fat tissues, such that a gain in adipose tissue occurs at the expense of bone loss. Fat-producing adipocytes and bone-forming osteoblasts stem from a common mesenchymal progenitor cell. Runx2 positively regulates the commitment of the mesenchymal cell toward osteogenesis, but its effects on energy homeostasis and the insulin signaling pathway are unknown. To investigate the connection, focused microarray profiling of genes associated with the insulin signaling pathway was performed on calvarial cells from Runx2-null embryonic mice and 3T3-L1 preadipocytes treated with control and insulin-containing media. The microarray showed that addition of insulin resulted in a robust induction of genes (>95%) in 3T3-L1 cells. Surprisingly, Runx2-null cells cultured in control media were at an elevated state of energy metabolism and addition of insulin resulted in a marked suppression of genes required for insulin signaling. Clustering analysis revealed that the suppression occurred at all stages of the insulin pathway, from the receptors and transducers to nuclear effectors and target genes. Taken together, these results demonstrate that Runx2 is central for transduction and execution of the insulin regulatory signal. In conclusion, Runx2 actively regulates the gene network required for glucose metabolism and energy homeostasis in mesenchymal cells.
Physical Activity and Self-Reported Cardiovascular Comorbidities in Persons with Multiple Sclerosis: Evidence from a Cross-Sectional Analysis
Authors: Motl Robert W. , Fernhall Bo , McAuley Edward , Cutter Gary
Published: May 2011

Background: This study examined the possibility of a linear, inverse association between physical activity and the number of self-reported cardiovascular comorbidities in persons with multiple sclerosis (MS). Methods: The sample included 561 persons with MS who completed demographic, cardiovascular comorbidity, disability status, and physical activity self-report assessments, and then wore an accelerometer for 7 days. The data were analyzed using bivariate correlation and multiple linear regression analyses. Results: Bivariate correlation analysis indicated that there were statistically significant, inverse associations between the number of self-reported cardiovascular comorbidities and objectively measured (r = –0.192, p = 0.0001) and self-reported (r = –0.151, p = 0.0001) physical activity. The first multiple linear regression indicated that objectively measured physical activity was significantly associated with the number of self-reported cardiovascular comorbidities (B = –0.003, SE B = 0.001, β = –0.128), even after controlling for confounding variables. The second multiple linear regression indicated that self-reported physical activity, too, was significantly associated with the number of self-reported cardiovascular comorbidities (B = –0.011, SE B = 0.004, β = –0.114), even after controlling for confounding variables. Conclusion: Physical activity was associated with the number of self-reported cardiovascular comorbidities, independent of disability status and other possible confounding variables, in persons with MS.
Apolipoprotein E Mediates Enhanced Plasma High-Density Lipoprotein Cholesterol Clearance by Low-Dose Streptococcal Serum Opacity Factor via Hepatic Low-Density Lipoprotein Receptors In Vivo
Authors: Rosales Corina , Tang Daming , Gillard Baiba K. , Courtney Harry S. , Pownall Henry J.
Published: May 2011

Objective—

Recombinant streptococcal serum opacity factor (rSOF) mediates the in vitro disassembly of human plasma high-density lipoprotein (HDL) into lipid-free apolipoprotein (apo) A-I, a neo-HDL that is cholesterol poor, and a cholesteryl ester–rich microemulsion (CERM) containing apoE. Given the occurrence of apoE on the CERM, we tested the hypothesis that rSOF injection into mice would reduce total plasma cholesterol clearance via apoE-dependent hepatic low-density lipoprotein receptors (LDLR).

Methods and Results—

rSOF (4 μg) injection into wild-type C57BL/6J mice formed neo-HDL, CERM, and lipid-free apoA-I, as observed in vitro, and reduced plasma total cholesterol (−43%,
t
1/2
=44±18 minutes) whereas control saline injections had a negligible effect. Similar experiments with apoE
−/−
and LDLR
−/−
mice reduced plasma total cholesterol ≈0% and 20%, respectively. rSOF was potent; injection of 0.18 μg of rSOF produced 50% of maximum reduction of plasma cholesterol 3 hours postinjection, corresponding to a ≈0.5-mg human dose. Most cholesterol was cleared hepatically (>99%), with rSOF treatment increasing clearance by 65%.

Conclusion—

rSOF injection into mice formed a CERM that was cleared via hepatic LDLR that recognize apoE. This reaction could provide an alternative mechanism for reverse cholesterol transport.
Vascular Calcification and Aortic Fibrosis
Authors: Shao Jian-Su , Sierra Oscar L. , Cohen Richard , Mecham Robert P. , Kovacs Attila , Wang James , Distelhorst Kathryn , Behrmann Abraham , Halstead Linda R. , Towler Dwight A.
Published: May 2011

Objective—

Calcification and fibrosis reduce vascular compliance in arteriosclerosis. To better understand the role of osteopontin (OPN), a multifunctional protein upregulated in diabetic arteries, we evaluated contributions of OPN in male low-density lipoprotein receptor (LDLR)−/− mice fed a high-fat diet.

Methods and Results—

OPN had no impact on high-fat diet–induced hyperglycemia, dyslipidemia, or body composition. However, OPN−/−;LDLR−/− mice exhibited an altered time-course of aortic calcium accrual—reduced during initiation but increased with progression—versus OPN+/+;LDLR−/− controls. Collagen accumulation, chondroid metaplasia, and mural thickness were increased in aortas of OPN−/−;LDLR−/− mice. Aortic compliance was concomitantly reduced. Vascular reexpression of OPN (
SM22
-
OPN
transgene) reduced aortic
Col2A1
and medial chondroid metaplasia but did not affect atherosclerotic calcification,
Col1A1
expression, collagen accumulation, or arterial stiffness. Dosing with the proinflammatory OPN fragment SVVYGLR upregulated aortic
Wnt
and osteogenic gene expression, increased aortic β-catenin, and restored early-phase aortic calcification in OPN−/−;LDLR−/− mice.

Conclusion—

OPN exerts stage-specific roles in arteriosclerosis in LDLR−/− mice. Actions phenocopied by the OPN metabolite SVVYGLR promote osteogenic calcification processes with disease initiation. OPN limits vascular chondroid metaplasia, endochondral mineralization, and collagen accumulation with progression. Complete deficiency yields a net increase in arteriosclerotic disease, reducing aortic compliance and conduit vessel function in LDLR−/− mice.
Growth of Engineered Human Myocardium With Mechanical Loading and Vascular Coculture
Authors: Tulloch Nathaniel L. , Muskheli Veronica , Razumova Maria V. , Korte F. Steven , Regnier Michael , Hauch Kip D. , Pabon Lil , Reinecke Hans , Murry Charles E.
Published: May 2011

Rationale:

The developing heart requires both mechanical load and vascularization to reach its proper size, yet the regulation of human heart growth by these processes is poorly understood.

Objective:

We seek to elucidate the responses of immature human myocardium to mechanical load and vascularization using tissue engineering approaches.

Methods and Results:

Using human embryonic stem cell and human induced pluripotent stem cell–derived cardiomyocytes in a 3-dimensional collagen matrix, we show that uniaxial mechanical stress conditioning promotes 2-fold increases in cardiomyocyte and matrix fiber alignment and enhances myofibrillogenesis and sarcomeric banding. Furthermore, cyclic stress conditioning markedly increases cardiomyocyte hypertrophy (2.2-fold) and proliferation rates (21%) versus unconditioned constructs. Addition of endothelial cells enhances cardiomyocyte proliferation under all stress conditions (14% to 19%), and addition of stromal supporting cells enhances formation of vessel-like structures by ≈10-fold. Furthermore, these optimized human cardiac tissue constructs generate Starling curves, increasing their active force in response to increased resting length. When transplanted onto hearts of athymic rats, the human myocardium survives and forms grafts closely apposed to host myocardium. The grafts contain human microvessels that are perfused by the host coronary circulation.

Conclusions:

Our results indicate that both mechanical load and vascular cell coculture control cardiomyocyte proliferation, and that mechanical load further controls the hypertrophy and architecture of engineered human myocardium. Such constructs may be useful for studying human cardiac development as well as for regenerative therapy.
Nfatc1 Coordinates Valve Endocardial Cell Lineage Development Required for Heart Valve Formation
Authors: Wu Bingruo , Wang Yidong , Lui Wendy , Langworthy Melissa , Tompkins Kevin L. , Hatzopoulos Antonis K. , Baldwin H. Scott , Zhou Bin
Published: May 2011

Rationale:

Formation of heart valves requires early endocardial to mesenchymal transformation (EMT) to generate valve mesenchyme and subsequent endocardial cell proliferation to elongate valve leaflets. Nfatc1 (nuclear factor of activated T cells, cytoplasmic 1) is highly expressed in valve endocardial cells and is required for normal valve formation, but its role in the fate of valve endocardial cells during valve development is unknown.

Objective:

Our aim was to investigate the function of Nfatc1 in cell-fate decision making by valve endocardial cells during EMT and early valve elongation.

Methods and Results:

Nfatc1
transcription enhancer was used to generate a novel valve endocardial cell–specific Cre mouse line for fate-mapping analyses of valve endocardial cells. The results demonstrate that a subpopulation of valve endocardial cells marked by the
Nfatc1
enhancer do not undergo EMT. Instead, these cells remain within the endocardium as a proliferative population to support valve leaflet extension. In contrast, loss of Nfatc1 function leads to enhanced EMT and decreased proliferation of valve endocardium and mesenchyme. The results of blastocyst complementation assays show that Nfatc1 inhibits EMT in a cell-autonomous manner. We further reveal by gene expression studies that Nfatc1 suppresses transcription of Snail1 and Snail2, the key transcriptional factors for initiation of EMT.

Conclusions:

These results show that Nfatc1 regulates the cell-fate decision making of valve endocardial cells during valve development and coordinates EMT and valve elongation by allocating endocardial cells to the 2 morphological events essential for valve development.
Railways and Population Distribution: France, Spain, and Portugal, 1870–2000
Authors: Mojica Laia , Martí-Henneberg Jordi
Published: May 2011

Transportion networks can have a profound influence on economic development and the distribution of population. A long-term comparative study of the influence that rail services exerted on urban growth reveals that the creation of a structured railway network in France, Portugal, and Spain intensified the depopulation of extensive rural areas, as more and more people moved to, and between, cities. Areas that were once relatively small and insignificant began to thrive when the railway reached them.
Urbanization and Transportation in Finland, 1880–1970
Authors: Kotavaara Ossi , Antikainen Harri , Rusanen Jarmo
Published: May 2011

Analysis based on historical geographical information systems (hgis) databases can be used to trace the relationship between railway infrastructure and population change in Finland from 1880 to 1970. The use of accessibility calculations, statistical analyses, and gis reveals that Finland's population was almost evenly distributed in 1880, when railway development began, but that immigration to cities was well underway by 1970, when motorization by road was rapidly becoming the primary form of transportation.
Regional Transformations of a State under Construction: Bulgaria, 1878–2002
Authors: Stanev Kaloyan , Martí-Henneberg Jordi , Ivanov Martin
Published: May 2011

Analysis of new regional socioeconomic and transport data in a gis format reveals that Bulgaria's most dramatic transformations occurred before World War I, corresponding to the construction of the national railway grid. Contrary to expectations, the massive socioeconomic developments that followed World War II and the fall of the Berlin Wall did not affect the regional economic order of the state.
The Madden–Julian Oscillation and the Relative Value of Deterministic Forecasts of Extreme Precipitation in the Contiguous United States
Authors: Jones Charles , Carvalho Leila M. V. , Gottschalck Jon , Higgins Wayne
Published: May 2011

The Madden–Julian oscillation (MJO) is the most prominent form of tropical intraseasonal variability that impacts weather and climate. Forecast skill of extreme precipitation in the contiguous United States (CONUS) during winter is higher when the MJO is active and has enhanced convection over the Western Hemisphere, Africa, and/or the western Indian Ocean. This study applies a simple decision model to examine the relationships between the MJO and the relative value of deterministic forecasts of extreme precipitation. Value in the forecasts is significantly higher and extends to longer leads (2 weeks) during active MJO.