Morphological and Electrochemical Properties of Crystalline Praseodymium Oxide Nanorods

Highly crystalline Pr₆O₁₁ nanorods were prepared by a simple precipitation method of triethylamine complex at 500°C. Synthesized Pr₆O₁₁ nanorods were uniformly grown with the diameter of 12–15 nm and the length of 100–150 nm without any impurities of unstable PrO₂ phase. The Pr₆O₁₁ nanorod electrodes attained a high electrical conductivity of 0.954 Scm⁻¹ with low activation energy of 0.594 eV at 850°C. The electrochemical impedance study showed that the resistance of electrode was significantly decreased at high temperature, which resulted from its high conductivity and low activation energy. The reduced impedance and high electrical conductivity of Pr₆O₁₁ nanorod electrodes are attributed to the reduction of grain boundaries and high space charge width.     

TD-LTE:抢占无线全新商机带动全球发展势态

LTE是目前大部分电信运营商首选的下一代移动通信技术,已有100多家运营商承诺将于2010年开始部署LTE.不过,在非成对频段部署LTE的商机却常被忽略.     

Multifractal analysis of Mg-doped ZnO thin films deposited by sol–gel spin coating method

A multifractal analysis has been performed on the 3D (three-dimensional) surface microtexture of magnesium-doped zinc oxide (ZnO:Mg) thin films with doping concentration of 0, 2, 4, and 5%. Thin films were deposited onto the glass substrates via the sol–gel spin coating method. The effect of magnesium doping, on the crystal structure, morphology, and band gap for ZnO:Mg thin films has been analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and UV–Vis spectroscopy. It has been observed that the surface of ZnO thin films is multifractal in nature. However, multifractality and complexity observed to decrease with increasing content of Mg in ZnO thin films due to formation of islands on the surface in accordance with Volmer–Weber growth mechanism. The investigations revealed that crystallinity, microtexture, morphology, and optical properties of the thin films can be tuned by controlling the Mg content within the ZnO lattice. In particular, their optical band gap energies were 3.27, 3.31, 3.34, and 3.33 eV at 0, 2, 4, and 5%, respectively. The prepared thin films of ZnO:Mg with tuned characteristics would have promising applications in optoelectronic devices.     

The role of visual occlusion in altitude maintenance during simulated flight.

The use of visual occlusion as a cue to altitude maintenance in low-altitude flight (LAF) was investigated. The extent to which the ground surface is occluded by 3-D objects varies with altitude and depends on the height, radius, and density of the objects. Participants attempted to maintain a constant altitude during simulated flight over an undulating terrain with trees of various heights, radii, and densities. As would be predicted if participants used occlusion, root-mean-square error was related to the product of tree height and tree density (Experiment 1) and to the product of tree radius and tree density (Experiment 2). This relationship was also found for simulated terrains with a more realistic mixture of tree heights (Experiment 4). The authors present a modification to an occlusion model (T. Leung & J. Malik, 1997) that can be used to approximate occlusion in the context of LAF, and they evaluate the modified model using the present LAF data. On a practical level, simulating 3-D objects is computationally expensive. The present results suggest that performance may be maintained with fewer objects if their size is increased. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cellular uptake properties of a 2''-amino/2''-O-methyl-modified chimeric hammerhead ribozyme targeted to the epidermal growth factor receptor mRNA

PURPOSE: Rhabdomyosarcomas (RMS) are heterogeneous in their clinical presentation, histology, and cytogenetics. The growth of some RMS cells has been found to be regulated by the tyrosine kinase insulin-like growth factor (IGF) type I receptor. However, RMS cells exhibit variable sensitivity to inhibitors of tyrosine kinases and IGF receptors. Collectively, these heterogeneous features suggest that differences exist in the growth regulatory pathways of RMS. The objective of this study is to identify active tyrosine kinase signal transduction pathways in embryonal and alveolar RMS cells. METHODS: RMS tumor samples and cell lines representing both embryonal and alveolar histologic subtypes have been analyzed by immunoprecipitation and immunoblotting techniques to characterize phosphotyrosyl protein patterns and to identify tyrosine phosphorylated proteins. RESULTS: RMS cells can be characterized based on the patterns of phosphotyrosyl proteins, including the phosphorylation status of the catenin-like protein Cas1 and the signal adapter protein SHC, and the activation of IGF type I receptor signaling cascades including the formation of SHC-GRB2 signal protein complexes and MAP kinase activation. CONCLUSIONS: Rhabdomyosarcomas, especially the embryonal histologic subtype, are heterogeneous at the level of tyrosine kinase signal transduction. It will be important to characterize the growth regulatory pathways active in individual RMS tumors before targeting molecular therapies to this malignancy.     

Subunit exchange of lens alpha-crystallin: a fluorescence energy transfer study with the fluorescent labeled alphaA-crystallin mutant W9F as a probe

A chemical study of the common Caribbean sea plume Pseudopterogorgia acerosa from Puerto Rico has produced two previously undescribed secondary metabolites. One of them, 1, is a new representative of the pseudopterane family of diterpenes possessing the uncommon 3,4;5,6 diepoxyfuran moiety. The other metabolite, 2, is a rare norcembranolide diterpene. Their chemical structures, including relative stereochemistry, were established by detailed analysis of the spectral data in addition to NMR spectral comparisons with known pseudopterane and cembrane models.     

RF electro-thermal modeling of LDMOSFETs for power-amplifier design

A new approach for the electro-thermal modeling of LDMOSFETs for power-amplifier design that bypasses pulsed-IVs and pulsed-RF measurements is presented in this paper. The existence of low-frequency dispersion in LDMOSFETs is demonstrated by comparing pulsed IVs with iso-thermal IVs. The modeling technique uses iso-thermal IV and microwave measurements to obtain the temperature dependence of small-signal parameters. Optimized tensor-product B-splines, which distribute knots to minimize fitting errors, are used to represent the small-signal parameters and extract the large-signal model as a function of voltages and temperature. The model is implemented on ADS and is verified by simulating and measuring the power harmonics and IMD large-signal performance of a power amplifier. The impact on the model of temperature-dependent drain and gate charge is investigated. The presented model is found to compare well and, in some cases, exceed the existing MET model for LDMOSFETs     

RADIATION EFFECT ON BIOSYNTHESES OF ASCORBIC ACID AND RIBOFLAVIN IN GERMINATING CHICKPEA

The influence of irradiation on biosyntheses of ascorbic acid and riboflavin in germinating chickpea seeds at ambient (25-35℃) conditions, was investigated. The rate of syntheses of these vitamins significantly increased with increasing germination time upto 120 h depending upon the treatment (P<0.05). Maximum amounts of ascorbic acid, 22.32 and 16.84 mg/100g, were found in the 0.10 kGy sample after 120 h of germination in tap and distilled water respectively. However, a radiation dose of 0.15 kGy resulted in the development of maximum values of riboflavin, 11.40 and 11.38 μ g/g, on germination in tap and distilled water respectively. A significant linear relation (r = 0-954 to 0.997) was observed between the biosyntheses of these vitamins and the germination time upto 120 h of irradiated and unirradiated chickpea seed (P<0.05).     

TSAT is a better predictor than ferritin of hemoglobin response to Epoetin alfa in US dialysis patients

Clinical guidelines recommend concurrent treatment of anemia in end‐stage renal disease with erythropoiesis‐stimulating agents (ESAs) and iron. However, there are mixed data about optimal iron supplementation. To help address this gap, the relationship between iron markers and hemoglobin (Hb) response to ESA (Epoetin alfa) dose was examined. Electronic medical records of 1902 US chronic hemodialysis patients were analyzed over a 12‐month period between June 2009 and June 2010. The analysis included patients who had at least one Hb value during each 4‐week interval for four consecutive intervals (k ? 2, k ? 1, k, and k + 1; k is the index interval), received at least one ESA dose during intervals k ? 1 or k, had at least one transferrin saturation (TSAT) value at interval k, and at least one ferritin value during intervals k ? 2, k ? 1, or k. Effect modification by TSAT and ferritin on Hb response was evaluated using the generalized estimating equations approach. Patients had a mean (standard deviation) age of 62 (15) years; 41% were Caucasian, 34% African American, 65% had hypertension, and 39% diabetes. Transferrin saturation, but not ferritin, had a statistically significant (P < 0.05) modifying effect on Hb response. Maximum Hb response was achieved when TSAT was 34%, with minimal incremental effect beyond these levels. Of the two standard clinical iron markers, TSAT should be used as the primary marker of the modifying effect of iron on Hb response to ESA. Long‐term safety of iron use to improve Hb response to ESA warrants further study.