Two-dimensional fluid model simulation of bell jar top inductively coupled plasma

In the present paper, argon (Ar) plasmas in a bell jar inductively coupled plasma (ICP) source are systematically studied over pressures from 5 to 20 mtorr and power inputs from 0.2 to 0.5 kW. In this study, both a two-dimensional (2-D) fluid model simulation and global model calculation are compared, The 2-D fluid model simulation with a self-consistent power deposition is developed to describe the Ar plasma behavior as well as predict the plasma parameter distributions, Finally, a quantitative comparison between the global model and the fluid model is made to test their validity.

Coflow jets with large velocity difference - a new aerodynamic principle of flame stabilization and combustion intensification

A new aerodynamic principle of flame stabilization and combustion intensification, the coflow jets with large velocity difference, is described. One or more small high-velocity jets of air or steam, injected off the axis and in the same direction as the low-velocity main fuel-air flow into the combustor, create a large recirculation zone of high turbulence intensity in which the combustibles and high temperature gases are effectively mixed, so that stable and intensive combustion can be maintained even for fuels with poor ignition. A pulverized coal combustor based on the principle mentioned above is shown to be characteristic of excellent combustoom and a simple structure. A number of precombustors of this type are in operation at some power stations and industrial boilers of China. Using such precombustor, successtul startups and part-load operation of the boilers have become available under conditions of unpreheated air and low-grade coal with volatiles as low as 15% and ash content as high as 30%. This principle shows good promise as an attractive new technology of combustion.

水射流辅助破岩机理研究(2)——水滴撞击

利用MSC.Dytran中的具有强度的多材料欧拉网格模拟水滴和有限长连续射流对靶板(岩石)的高速冲击作用,研究了靶板破坏深度、破坏宽度与水滴初压力、速度、入射方向、板厚以及连续射流的密度等的关系及其物理意义.用应力波理论来解释靶板的层裂现象,试图多角度分析射流破岩机理.

Experimental Study on Flow Induced Vibration of a Cylinder with Two Degrees of Freedom Near a Rigid Wall

The flow-induced vibration of a cylinder with two degrees of freedom near a rigid wall under the action of steady flow is investigated experimentally. The vibration amplitude and frequency of the cylinder and the vortex shedding frequency at the wake flow region of the cylinder are measured. The influence of gap-to-diameter ratio upon the amplitude response is analyzed. The experimental results indicate that when the reduced velocity (Vr) is in the range of 1.2 < Vr < 2.6, only streamwise vibration with small amplitude occurs, whose frequency is quite close to its natural frequency in the still water. When the reduced velocity Vr > 3.4, both the streamwise and transverse vibrations of the cylinder occur. In this range, the amplitudes of transverse vibration are much larger than those of streamwise vibrations, and the amplitudes of the streamwise vibration also get larger than those at the range of 1.2 < Vr < 2.6. At the range of Vr > 3.4, the frequency of streamwise vibration undergoes a jump at certain values of Vr, at which the streamwise vibrating frequency is twice as much as the transverse one. However, when the streamwise vibration does not experience a jump, its frequency is the same as that of the transverse vibration. The maximum values of second streamwise and transverse vibration amplitudes increase with increasing gap-to-diameter ratios.

Investigation of laser-induced damage on multi-layer dielectric gratings

We investigate mechanisms of laser induced damage thresholds (LIDTs) of multi-layer dielectric gratings (AIDG,). It is found that the laser damage thresholds of MDGs and unstructured dielectric multi-layer coatings (the substrate of MDG) are 3.15J/cm(2) and 9.32 J/cm(2), respectively, at 1064nm (12ns) with the Littrow angle 51.2 degrees and the TEM00 mode. The laser-induced damage mechanism of multi-layer dielectric is presented with the analysis of the following factors: The dominant factor is the pollution on the corrugated surface, which is induced by the complex manufacture process of multi-layer dielectric gratings; another is the electric field distribution along the corrugated surface. The third reason is due to the reduction in stoichiometry of oxide films, resulting from the manufacture process of etching.

Tandem chromosome fusions in karyotypic evolution of Muntiacus: evidence from M-feae and M-gongshanensis

The muntjacs (Muntiacus, Cervidae) are famous for their rapid and radical karyotypic diversification via repeated tandem chromosome fusions, constituting a paradigm for the studies of karyotypic evolution. Of the five muntjac species with defined karyotyp

Defining the orientation of the tandem fusions that occurred during the evolution of Indian muntjac chromosomes by BAC mapping

The Indian muntjac (Muntiacus muntjak vaginalis) has a karyotype of 2n=6 in the female and 7 in the male, the karyotypic evolution of which through extensive tandem fusions and several centric fusions has been well-documented by recent molecular cytogenetic studies. In an attempt to define the fusion orientations of conserved chromosomal segments and the molecular mechanisms underlying the tandem fusions, we have constructed a highly redundant (more than six times of whole genome coverage) bacterial artificial chromosome (BAC) library of Indian muntjac. The BAC library contains 124,800 clones with no chromosome bias and has an average insert DNA size of 120 kb. A total of 223 clones have been mapped by fluorescent in situ hybridization onto the chromosomes of both Indian muntjac and Chinese muntjac and a high-resolution comparative map has been established. Our mapping results demonstrate that all tandem fusions that occurred during the evolution of Indian muntjac karyotype from the acrocentric 2n=70 hypothetical ancestral karyotype are centromere-telomere (head-tail) fusions.

Origin and evolution of new exons in rodents

Gene number difference among organisms demonstrates that new gene origination is a fundamental biological process in evolution. Exon shuffling has been universally observed in the formation of new genes. Yet to be learned are the ways new exons originate and evolve, and how often new exons appear. To address these questions, we identified 2695 newly evolved exons in the mouse and rat by comparing the expressed sequences of 12,419 orthologous genes between human and mouse, using 743,856 pig ESTs as the outgroup. The new exon origination rate is about 2.71 x 10(-3) per gene per million years. These new exons have markedly accelerated rates both of nonsynonymous substitutions and of insertions/ deletions (indels). A much higher proportion of new exons have Kappa(a)/Kappa(s) ratios > 1 (where K-a is the nonsynonymous substitution rate and K-s is the synonymous substitution rate) than K do the old exons shared by human and mouse, implying a role of positive selection in the rapid evolution. The majority of these new exons have sequences unique in the genome, suggesting that most new exons might originate through "exonization" of intronic sequences. Most of the new exons appear to be alternative exons that are expressed at low levels.

The Effects of Visual Object Size in The Depth Perception in KM Mouse

Whether mice perceive the depth of space dependent on the visual size of object targets was explored when visual cues such as perspective and partial occlusion in space were excluded. A mouse was placed on a platform the height of which is adjustable. The platform located inside a box in which all other walls were dark exception its bottom through that light was projected as a sole visual cue. The visual object cue was composed of 4x4 grids to allow a mouse estimating the distance of the platform relative to the grids. Three sizes of grids reduced in a proportion of 2/3 and seven distances with an equal interval between the platform and the grids at the bottom were applied in the experiments. The duration of a mouse staying on the platform at each height was recorded when the different sizes of the grids were presented randomly to test whether the Judgment of the mouse for the depth of the platform from the bottom was affected by the size information of the visual target. The results from all conditions of three object sizes show that time of mice staying on the platform became longer with the increase in height. In distance of 20 similar to 30 cm, the mice did not use the size information of a target to judge the depth, while mainly used the information of binocular disparity. In distance less than 20 cm or more than 30 cm, however, especially in much higher distance 50 cm, 60 cm and 70 cm, the mice were able to use the size information to do so in order to compensate the lack of binocular disparity information from both eyes. Because the mice have only 1/3 of the visual field that is binocular. This behavioral paradigm established in the current study is a useful model and can be applied to the experiments using transgenic mouse as an animal model to investigate the relationships between behaviors and gene functions.

Toll-like receptor 4 signaling pathway can be triggered by grass carp reovirus and Aeromonas hydrophila infection in rare minnow Gobiocypris rarus

Toll-like receptor 4 (TLR4) is critical for LPS recognition and cellular responses. It also recognizes some viral envelope proteins. Detection mostly results in the inflammation rather than specific antiviral responses. However, it's unclear in fish. In this report, a TLR4 gene (named as GrTLR4b) was cloned and characterized from rare minnow Gobiocypris rarus. The full length of GrTLR4b cDNA consists of 2766 nucleotides and encodes a polypeptide of 818 amino acids with an estimated molecular mass of 94,518 Da and a predicted isoelectric point of 8.41. The predicted amino acid sequence comprises a signal peptide, six leucine-rich repeat (LRR) motifs, one leucine-rich repeat C-terminal (LRRCT) motif, followed by a transmembrane segment of 23 amino acids, and a cytoplasmic region of 167 amino acids containing one Toll - interleukin 1 - receptor (TIR) motif. It's closely similar to the zebrafish (Danio rerio) TLR4b amino acid sequence with an identity of 77%. Quantitative RT-PCR analysis showed GrTLR4b mRNA was constitutive expression in gill, heart, intestine, kidney, liver, muscle and spleen tissues in healthy animals and up-regulated by viruses and bacteria. After being infected by grass carp reovirus or Aeromonas hydrophila, GrTLR4b expressions were up-regulated from 24 h post-injection and lasted until the fish became moribund (P < 0.05). These data implied that TLR4 signaling pathway could be activated by both viral and bacterial infection in rare minnow. (C) 2009 Elsevier Ltd. All rights reserved.

Enhanced grass carp reovirus resistance of Mx-transgenic rare minnow (Gobiocypris rarus)

In the interferon-induced antiviral mechanisms, the Mx pathway is one of the most powerful. Mx proteins have direct antiviral activity and inhibit a wide range of viruses by blocking an early stage of the viral genome replication cycle. However, antiviral activity of piscine Mx remains unclear in vivo. In the present study, an Mx-like gene was cloned, characterized and gene-transferred in rare minnow Gobiocypris rarus, and its antiviral activity was confirmed in vivo. The full length of the rare minnow Mx-like cDNA is 2241 bp in length and encodes a polypeptide of 625 amino acids with an estimated molecular mass of 70.928 kDa and a predicted isoelectric point of 7.33. Analysis of the deduced amino acid sequence indicated that the mature peptide contains an amino-terminal tripartite GTP-binding motif, a dynamin family signature sequence, a GTPase effector domain and two carboxy-terminal leucine zipper motifs, and is the most similar to the crucian carp (Carassius auratus) Mx3 sequence with an identity of 89%. Both P0 and F1 generations of Mx-transgenic rare minnow demonstrated very significantly high survival rate to GCRV infection (P < 0.01). The mRNA expression of Mx gene was consistent with survival rate in F1 generation. The virus yield was also concurrent with survival time using electron microscope technology. Rare minnow has Mx gene(s) of its own but introducing more Mx gene improves their resistance to GCRV. Mx-transgenic rare minnow might contribute to control the GCRV diseases. (C) 2008 Published by Elsevier Ltd.

Long rectangle resonator 1550 nm AlGaInAs/InP lasers

1550 nm AlGaInAs/InP long rectangle resonator lasers with three sides surrounded by SiO2 and p electrode layers are fabricated by planar technology, and room-temperature continuous-wave lasing is realized for a laser with a length of 53 mu m and a width of 2 mu m. Multiple peaks with wavelength intervals of Fabry-Perot mode intervals and mode Q factors of about 400 and a lasing mode with a Q factor over 8000 are observed from the lasing spectrum at threshold current. The numerical results of the FDTD simulation indicate that the lasing mode may be a whispering-gallery mode, which is a coupled mode of two high-order transverse modes of the waveguide.

Defects in gallium nitride nanowires: First principles calculations

Atomic configurations and formation energies of native defects in an unsaturated GaN nanowire grown along the [001] direction and with (100) lateral facets are studied using large-scale ab initio calculation. Cation and anion vacancies, antisites, and interstitials in the neutral charge state are all considered. The configurations of these defects in the core region and outermost surface region of the nanowire are different. The atomic configurations of the defects in the core region are same as those in the bulk GaN, and the formation energy is large. The defects at the surface show different atomic configurations with low formation energy. Starting from a Ga vacancy at the edge of the side plane of the nanowire, a N-N split interstitial is formed after relaxation. As a N site is replaced by a Ga atom in the suboutermost layer, the Ga atom will be expelled out of the outermost layers and leaves a vacancy at the original N site. The Ga interstitial at the outmost surface will diffuse out by interstitialcy mechanism. For all the tested cases N-N split interstitials are easily formed with low formation energy in the nanowires, indicating N-2 molecular will appear in the GaN nanowire, which agrees well with experimental findings.

Structural and electrical properties of (110) ZnO epitaxial thin films on (001) SrTiO3 substrates

(110) oriented ZnO thin films were epitaxially prepared on (001) SrTiO3 single crystal substrates by a pulsed laser deposition method. The evolution of structure, surface morphology, and electrical conductivity of ZnO films was investigated on changing the growth temperature. Two domain configurations with 90 degrees rotation to each other in the film plane were found to exist to reduce the lattice mismatch between the films and substrates. In the measured temperature range between 80 K and 300 K, the electrical conductivity can be perfectly fitted by a formula of a (T) = sigma(0) + aT(b/2). implying that the electron-phonon scattering might have a significant contribution to the conductivity. (C) 2008 Elsevier Ltd. All rights reserved.