Common evolutionary origin of aquareoviruses and orthoreoviruses revealed by genome characterization of Golden shiner reovirus, Grass carp reovirus, Striped bass reovirus and golden ide reovirus (genus Aquareovirus, family Reoviridae)

Full-length and partial genome sequences of four members of the genus Aquareovirus, family Reoviridae (Golden shiner reovirus, Grass carp reovirus, Striped bass reovirus and golden ide reovirus) were characterized. Based on sequence comparison, the unclassified Grass carp reovirus was shown to be a member of the species Aquareovirus C The status of golden ide reovirus, another unclassified aquareovirus, was also examined. Sequence analysis showed that it did not belong to the species Aquareovirus A or C, but assessment of its relationship to the species Aquareovirus B, D, E and F was hampered by the absence of genetic data from these species. In agreement with previous reports of ultrastructural resemblance between aquareoviruses and orthoreoviruses, genetic analysis revealed homology in the genes of the two groups. This homology concerned eight of the 11 segments of the aquareovirus genome (amino acid identity 17-42%), and similar genetic organization was observed in two other segments. The conserved terminal sequences in the genomes of members of the two groups were also similar. These data are undoubtedly an indication of the common evolutionary origin of these viruses. This clear genetic relatedness between members of distinct genera is unique within the family Reoviridae. Such a genetic relationship is usually observed between members of a single genus. However, the current taxonomic classification of aquareoviruses and orthoreoviruses in two different genera is supported by a number of characteristics, including their distinct G+C contents, unequal numbers of genome segments, absence of an antigenic relationship, different cytopathic effects and specific econiches.

Structural, mechanical, thermodynamic, and electronic properties of thorium hydrides from first-principles

We perform first-principles calculations of the structural, electronic, mechanical, and thermodynamic properties of thorium hydrides (ThH2 and Th4H15) based on the density functional theory with generalized gradient approximation. The equilibrium geometries, the total and partial densities of states, charge density, elastic constants, elastic moduli, Poisson's ratio, and phonon dispersion curves for these materials are systematically investigated and analyzed in comparison with experiments and previous calculations. These results show that our calculated equilibrium structural parameters are well consistent with experiments. The Th-H bonds in all thorium hydrides exhibit weak covalent character, but the ionic properties for ThH2 and Th4H15 are different due to their different hydrogen concentration. It is found that while in ThH2 about 1.5 electrons transfer from each Th atom to H, in Th4H15 the charge transfer from each Th atom is around 2.1 electrons. Our calculated phonon spectrum for the stable body-centered tetragonal phase of ThH2 accords well with experiments. In addition we show that ThH2 in the fluorite phase is mechanically and dynamically unstable.

Nanostructure in the p-layer and its impacts on amorphous silicon solar cells

The open circuit voltage (V-oc) of n-i-p type hydrogenated amorphous silicon (a-Si:H) solar cells has been examined by means of experimental and numerical modeling. The i- and p-layer limitations on V-oc are separated and the emphasis is to identify the impact of different kinds of p-layers. Hydrogenated protocrystalline, nanocrystalline and microcrystalline silicon p-layers were prepared and characterized using Raman spectroscopy, high resolution transmission electron microscopy (HRTEM), optical transmittance and activation energy of dark-conductivity. The n-i-p a-Si:H solar cells incorporated with these p-layers were comparatively investigated, which demonstrated a wide variation of V-oc from 1.042 V to 0.369 V, under identical i- and n-layer conditions. It is found that the nanocrystalline silicon (nc-Si:H) p-layer with a certain nanocrystalline volume fraction leads to a higher V-oc. The optimum p-layer material for n-i-p type a-Si:H solar cells is not found at the onset of the transition between the amorphous to mixed phases, nor is it associated with a microcrystalline material with a large grain size and a high volume fraction of crystalline phase. (c) 2006 Elsevier B.V. All rights reserved.

Quasi-thermo dynamic analysis of MOVPE growth of GaxAlyIn1-x-yN

A quasi-thermodynamic model of metalorganic vapor phase epitaxy (MOVPE) growth of GaxAlyIn1-x-yN alloys has been proposed. In view of the complex growth behavior of GaxAlyIn1-x-yN, we focus our attention on the galliumrich quaternary alloys that are lattice matched to GaN, In0.15Ga0.85N or Al0.15Ga0.85N, which are widely used in the GaN-based optoelectronic devices. The relationship between GaAlInN alloy composition and input molar ratio of group III metalorganic compounds at various growth conditions has been calculated. The influence of growth temperature, nitrogen fraction in the carrier gas, input partial pressure of group III metalorganics, reactor pressure, V/III ratio and the decomposition rate of ammonia on the composition of deposited alloys are studied systematically. Based on these calculated results, we can find out the appropriate growth conditions for the MOVPE growth of GaxAlyIn1-x-yN alloy lattice matched to GaN, In0.15Ga0.85N or Al0.15Ga0.85N. (C) 2002 Elsevier Science B.V. All rights reserved.

Crystallographic and magnetic properties of nitride R3Fe29-xCrxN4 (R = Y, Ca, Nd, Sm, Gd, Tb, and Dy)

A systematic investigation of crystallographic and magnetic properties of nitride R3Fe29-xCrxN4 (R=Y, Ce, Nd, Sm, Gd, Tb, and Dy) has been performed. The lattice constants and unit cell volume decrease with increasing rare earth atomic number from Nd to Dy, reflecting the lanthanide contraction. After nitrogenation the relative volume expansion of each nitride is around between 5% and 7%. The nitrogenation results in a good improvement in the Curie temperature, the saturation magnetization and anisotropy fields at 4.2 K, and room temperature for R3Fe29-xCrxN4. Magnetohistory effects of R3Fe29-xCrxN4 and R3Fe29-xCrx (R=Nd and Sm) are observed in a low field of 0.04 T. First order magnetization process occurs in Sm3Fe24.0Cr5.0N4 in magnetic fields of 2.8 T at 4.2 K. After nitrogenation, the easy magnetization direction of Sm3Fe24.0Cr5.0 is changed from the easy-cone structure to the uniaxial. The good intrinsic magnetic properties of Sm3Fe24.0Cr5.0N4 make this compound a hopeful candidate for new high-performance hard magnets. (C) 1998 American Institute of Physics.

Crystallographic and magnetic properties of R3Fe29-xVxN4 (R = Y, Ce, Nd, Sm, Gd, Tb, and Dy)

A systematic investigation of crystallographic and magnetic properties of nitride R3Fe29-xVxN4 (R = Y, Ce, Nd, Sm, Gd, Tb, and Dy) has been performed. Nitrogenation leads to a relative volume expansion of about 6%. The lattice constants and unit cell volume decrease with increasing rare-earth atomic number from Nd to Dy, reflecting the lanthanide contraction. On average, the Curie temperature increases due to the nitrogenation to about 200 K compared with its parent compound. Generally speaking, nitrogenation also results in a remarkable improvement of the saturation magnetization and anisotropy fields at 4.2 K and room temperature for R3Fe29-xVxN4 compared with their parent compounds. The transition temperature indicates the spin reorientations of R3Fe29-xVxN4 for R = Nd and Sm are at around 375 and 370 K which are higher than that of R3Fe29-xVx, for R = Nd and Sm 145 and 140 K, respectively. The magnetohistory effects of R3Fe29-xVxN4 (R = Ce, Nd, and Sm) are observed in low fields of 0.04 T. After nitrogenation the easy magnetization direction of Sm3Fe26.7V2.3 is changed from an easy-cone structure to the b-axis. As a preliminary result, a maximum remanence B-r of 0.94 T, an intrinsic coercivity mu(0)H(C) of 0.75 T, and a maximum energy product (B H)(max) of 108.5 kJ m(-3) for the nitride magnet Sm3Fe26.7V2.3N4 are achieved by ball-milling at 293 K.

Structure and magnetic properties of nitrides R3Fe29-xCrxN4

A systematic investigation of nitrides R3F29-xCrxN4 (R = Y, Ce, Nd, Sm, Gd, Tb, and Dy) has been performed. The nitrogen concentration in the nitride R3Fe29-xCrxNy was determined to be y = 4. Nitrogenation leads to a relative volume expansion of about 5.3%. The lattice constants and unit cell volume decrease with increasing rare earth atomic number from Nd to Dy, reflecting the lanthanide contraction. In average, the increase of Curie temperature upon nitrogenation is about 200 K, compared with its parent compound. The nitrogenation also results in a remarkable improvement in the saturation magnetization and anisotropy fields for R3Fe29-x CrxN4 at 4.2 K and room temperature, compared with their parent compounds. A spin reorientation of Nd3Fe24.5Cr4.5N4 occurs at around 368 K, which is 138 K higher than that of Nd3F24.5Cr4.5. Magnetohistory effects of R3Fe29-xCrxN4 (R = Nd and Sm) are observed in a low field of 0.04 T. First-order magnetization process occurs in Sm3Fe24.0Cr5.0N4 in magnetic fields of around 3.0 T at 4.2 K. After nitrogenation the easy magnetization direction of Sm3Fe24.0C5.0 is changed from the easy-cone structure to the uniaxial. The excellent intrinsic magnetic properties of Sm3Fe24.0Cr5.0N4 make this compound a hopeful candidate for new high-performance permanent magnets.

Nanostructure in the p-layer and its impacts on amorphous silicon solar cells

The open circuit voltage (V-oc) of n-i-p type hydrogenated amorphous silicon (a-Si:H) solar cells has been examined by means of experimental and numerical modeling. The i- and p-layer limitations on V-oc are separated and the emphasis is to identify the impact of different kinds of p-layers. Hydrogenated protocrystalline, nanocrystalline and microcrystalline silicon p-layers were prepared and characterized using Raman spectroscopy, high resolution transmission electron microscopy (HRTEM), optical transmittance and activation energy of dark-conductivity. The n-i-p a-Si:H solar cells incorporated with these p-layers were comparatively investigated, which demonstrated a wide variation of V-oc from 1.042 V to 0.369 V, under identical i- and n-layer conditions. It is found that the nanocrystalline silicon (nc-Si:H) p-layer with a certain nanocrystalline volume fraction leads to a higher V-oc. The optimum p-layer material for n-i-p type a-Si:H solar cells is not found at the onset of the transition between the amorphous to mixed phases, nor is it associated with a microcrystalline material with a large grain size and a high volume fraction of crystalline phase. (c) 2006 Elsevier B.V. All rights reserved.

STUDY OF MICROSTRUCTURE AND DEFECTS IN HYDROGENATED MICROCRYSTALLINE SILICON FILMS

Microcrystalline silicon films were deposited by very high frequency (VHF) plasma-enhanced chemical vapor deposition (PECVD) with different hydrogen dilution. The microstructure of these films was investigated using Raman spectroscopy and infrared absorption (IR) spectra. The crystalline, amorphous, and grain boundary volume fractions X-c, X-a and X-gb were estimated from Raman measurements. An interface structure factor (R-if) is proposed to characterize the grain boundary volume fractions in IR spectroscopy. The density of states (DOS) of the microcrystalline crystalline silicon films were studied by phase-shift analysis of modulated photocurrent (MPC) and photoconductivity spectroscopy. It was observed that DOS increases with increasing grain boundary volume fractions, while the values of electron mobility-lifetime product mu T-e(e) disease.

Partial oxidation reforming of biomass fuel gas over nickel-based monolithic catalyst with naphthalene as model compound

With naphthalene as biomass tar model compound, partial oxidation reforming (with addition of O-2) and dry reforming of biomass fuel gas were investigated over nickel-based monoliths at the same conditions. The results showed that both processes had excellent performance in upgrading biomass raw fuel gas. Above 99% of naphthalene was converted into synthesis gases (H-2+CO). About 2.8 wt% of coke deposition was detected on the catalyst surface for dry reforming process at 750 degrees C during 108 h lifetime test. However, no Coke deposition was detected for partial oxidation reforming process, which indicated that addition of O-2 can effectively prohibit the coke formation. O-2 Can also increase the CH4 conversion and H-2/CO ratio of the producer gas. The average conversion of CH4 in dry and partial oxidation reforming process was 92% and 95%, respectively. The average H-2/CO ratio increased from 0.95 to 1.1 with the addition of O-2, which was suitable to be used as synthesis gas for dimethyl ether (DME) synthesis.

A multi-moment finite volume formulation for shallow water equations on unstructured mesh

A novel and accurate finite volume method has been presented to solve the shallow water equations on unstructured grid in plane geometry. In addition to the volume integrated average (VIA moment) for each mesh cell, the point values (PV moment) defined on cell boundary are also treated as the model variables. The volume integrated average is updated via a finite volume formulation, and thus is numerically conserved, while the point value is computed by a point-wise Riemann solver. The cell-wise local interpolation reconstruction is built based on both the VIA and the PV moments, which results in a scheme of almost third order accuracy. Efforts have also been made to formulate the source term of the bottom topography in a way to balance the numerical flux function to satisfy the so-called C-property. The proposed numerical model is validated by numerical tests in comparison with other methods reported in the literature. (C) 2010 Elsevier Inc. All rights reserved.

Multiplex binding modes of toluidine blue with calf thymus DNA and conformational transition of DNA revealed by spectroscopic studies

It is noteworthy to understand the details of interactions between antitumor drugs and DNA because the binding modes and affinities affect their antitumor activities. Here, The interaction of toluidine blue (TB), a potential antitumor drug for photodynamic therapy of tumor, with calf thymus DNA (ctDNA) was explored by UV-vis, fluorescence, circular dichroism (CD) spectroscopy, UV-rnelting method and surface-enhance Raman spectroscopy (SERS). The experimental results suggest that TB could bind to ctDNA via both electrostatic interaction and partial intercalation.

beta-NaYF4 and beta-NaYF4:Eu3+ Microstructures: Morphology Control and Tunable Luminescence Properties

beta-NaYF4 hexagonal microprisms and microrods with different aspect ratios have been prepared via a simple hydrothermal route. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectra as well as kinetic decays were used to characterize the samples. The influences of reaction temperature and the molar ratio of NaF to y(3+) on the crystal phases and shapes of final products have been studied in detail. The aspect ratios of products increase gradually with the increase of reaction temperature and NaF/Y3+ molar ratio. The growth mechanisms of crystals prepared under the different conditions are presented systematically. More importantly, the systematical investigation on the luminescence properties of beta-NaYF4:xEu(3+) (x = 0.5, 1, 2, 3, 5, and 10 mol %) with hexagonally microprismatic morphology shows the characteristic emissions of Eu3+ (D-5(J)-F-7(J'), J, J' = 0, 1, 2, 3). Under the excitation of single wavelength light of 397 nm, the luminescence colors of the corresponding products can be tuned feasibly from bluish white to yellow to red by changing the doping concentration of Eu3+.

Synthesis and characterization of magnetic FexOy@SBA-15 composites with different morphologies for controlled drug release and targeting

Magnetic functionalization of the ordered mesoporous SBA-15 (SiO2) aggregate blocks and rice grain-like particles were realized by using a sol-gel method, resulting in the formation of FexOy@SBA-15 composite materials. The X-ray diffraction (XRD), N-2 adsorption/desorption, and transmission electron microscopy (TEM) results show that these composites conserved ordered mesoporous structure after the formation of FexOy nanoparticles in the pores and on the outer surface of SBA-15. It was confirmed by the XRD and X-ray photoelectron spectroscopy (XPS) analysis that the FexOy generated in these mesoporous silica hosts is mainly composed of gamma-Fe2O3. Magnetic measurements reveal that these composites possess superparamagnetic properties at 300 K. The saturation magnetization of these composites increased with the increasing loading amount of gamma-Fe2O3. These composites, which possess high surface area and high pore volume, show magnetic response sufficient for drug targeting in the presence of an external magnetic field.

Microstructures, mechanical properties and corrosion behavior of high-pressure die-cast Mg-4Al-0.4Mn-xPr (x=1, 2, 4, 6) alloys

Mg-4Al-0.4Mn-xPr (x = 1, 2, 4 and 6 wt.%) magnesium alloys were prepared successfully by the high-pressure die-casting technique. The microstructures, mechanical properties, corrosion behavior as well as strengthening mechanism were investigated. The die-cast alloys were mainly composed of small equiaxed dendrites and the matrix. The fine rigid skin region was related to the high cooling rate and the aggregation of alloying elements, such as Pr. With the Pr content increasing, the alpha-Mg grain sizes were reduced gradually and the amounts of the Al2Pr phase and All, Pr-3 phase which mainly concentrated along the grain boundaries were increased and the relative volume ratio of above two phases was changed. Considering the performance-price ratio, the Pr content added around 4 wt.% was suitable to obtain the optimal mechanical properties which can keep well until 200 degrees C as well as good corrosion resistance. The outstanding mechanical properties were mainly attributed to the rigid casting surface layer, grain refinement, grain boundary strengthening obtained by an amount of precipitates as well as solid solution strengthening.