1,978 research outputs found

    Transport properties of dense deuterium-tritium plasmas

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    Consistent descriptions of the equation of states, and information about transport coefficients of deuterium-tritium mixture are demonstrated through quantum molecular dynamic (QMD) simulations (up to a density of 600 g/cm3^{3} and a temperature of 10410^{4} eV). Diffusion coefficients and viscosity are compared with one component plasma model in different regimes from the strong coupled to the kinetic one. Electronic and radiative transport coefficients, which are compared with models currently used in hydrodynamic simulations of inertial confinement fusion, are evaluated up to 800 eV. The Lorentz number is also discussed from the highly degenerate to the intermediate region.Comment: 4 pages, 3 figure

    Lack of EGFR mutations benefiting gefitinib treatment in adenocarcinoma of esophagogastric junction

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    <p>Abstract</p> <p>Background</p> <p>The epidermal growth factor receptor (EGFR) inhibitor, gefitinib, has been reported to successfully treat advanced non-small cell lung cancer patients with genetic mutations in EGFR. The aim of this study was to investigate the existence of EGFR mutations in carcinoma of esophagogastric junction, and also to explore the possibility of treating carcinoma of esophagogastric junction using gefitinib.</p> <p>Methods</p> <p>From Aug. 2009 to Jun. 2010, 65 patients with carcinoma of esophagogastric junction underwent surgical resection. The tumor tissue and corresponding blood specimens were collected from all cases. The DNA was extracted and PCR amplification was accomplished based on designed primers for exons 18, 19, 20, and 21. EGFR exons 18, 19, 20 and 21 of both cancer cell and white blood cell were finally successfully sequenced.</p> <p>Results</p> <p>In exon 20, a variant from CAG to CAA at codon 787 (2361G-> A) was identified in 19 patients, which was a genomic variation of EGFR since it was found in both cancer tissue and white blood cells. This EGFR alteration was a synonymous single nucleotide polymorphism (SNP) since CAA and CAG were encoding the same amino-acid of Glutamine (Q787Q, NCBI database 162093G > A, SNP ID: rs10251977). No genetic alteration was found in exons 18, 19 or 21.</p> <p>Conclusions</p> <p>Adenocarcinoma of esophagogastric junction rarely presents EGFR mutation, especially gefitinib-associated mutations such as L858R, or delE746-A750. This means that the gefitinib-based gene target therapy should not be recommended for treating carcinoma of esophagogastric junction.</p

    Modulation of Gene Expression in Liver of Hibernating Asiatic Toads (Bufo gargarizans)

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    Hibernation is an effective energy conservation strategy that has been widely adopted by animals to cope with unpredictable environmental conditions. The liver, in particular, plays an important role in adaptive metabolic adjustment during hibernation. Mammalian studies have revealed that many genes involved in metabolism are differentially expressed during the hibernation period. However, the differentiation in global gene expression between active and torpid states in amphibians remains largely unknown. We analyzed gene expression in the liver of active and torpid Asiatic toads (Bufo gargarizans) using RNA-sequencing. In addition, we evaluated the differential expression of genes between females and males. A total of 1399 genes were identified as differentially expressed between active and torpid females. Of these, the expressions of 395 genes were significantly elevated in torpid females and involved genes responding to stresses, as well as contractile proteins. The expression of 1004 genes were significantly down-regulated in torpid females, most which were involved in metabolic depression and shifts in the energy utilization. Of the 715 differentially expressed genes between active and torpid males, 337 were up-regulated and 378 down-regulated. A total of 695 genes were differentially expressed between active females and males, of which 655 genes were significantly down-regulated in males. Similarly, 374 differentially expressed genes were identified between torpid females and males, with the expression of 252 genes (mostly contractile proteins) being significantly down-regulated in males. Our findings suggest that expression of many genes in the liver of B. gargarizans are down-regulated during hibernation. Furthermore, there are marked sex differences in the levels of gene expression, with females showing elevated levels of gene expression as compared to males, as well as more marked down-regulation of gene-expression in torpid males than females.Peer reviewe

    Binary solvent extraction system and extraction time effects on phenolic antioxidants from kenaf seeds (Hibiscus cannabinus L.) extracted by a pulsed ultrasonic-assisted extraction

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    The aim of this study was to determine the best parameter for extracting phenolic-enriched kenaf (Hibiscus cannabinus L.) seeds by a pulsed ultrasonic-assisted extraction. The antioxidant activities of ultrasonic-assisted kenaf seed extracts (KSE) were determined by a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity assay, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging assay, β-carotene bleaching inhibition assay, and ferric reducing antioxidant power (FRAP) assay. Total phenolic content (TPC) and total flavonoid content (TFC) evaluations were carried out to determine the phenolic and flavonoid contents in KSE. The KSE from the best extraction parameter was then subjected to high performance l.quid chromatography (HPLC) to quantify the phenolic compounds. The optimised extraction condition employed 80% ethanol for 15 min, with the highest values determined for the DPPH, ABTS, and FRAP assay. KSE contained mainly tannic acid (2302.20 mg/100 g extract) and sinapic acid (1198.22 mg/100 g extract), which can be used as alternative antioxidants in the food industry

    Nanotube ferroelectric tunnel junctions with giant tunneling electroresistance ratio

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    Low-dimensional ferroelectric tunnel junctions are appealing for the realization of nanoscale nonvolatile memory devices due to their inherent advantage of device miniaturization. Those based on current mechanisms still have restrictions including low tunneling electroresistance (TER) effects and complex heterostructures. Here, we introduce an entirely new TER mechanism to construct the nanotube ferroelectric tunnel junction with ferroelectric nanotubes as the tunneling region. When rolling a ferroelectric monolayer into a nanotube, due to the coexistence of its intrinsic ferroelectric polarization with the flexoelectric polarization induced by bending, there occurs metal-insulator transition depending on radiative polarization states. For the pristine monolayer, its out-of-plane polarization is tunable by an in-plane electric field, the conducting states of the ferroelectric nanotube can thus be tuned between metallic and insulating via axial electric means. Using {\alpha}-In2Se3 as an example, our first-principles density functional theory calculations and nonequilibrium Green's function formalism confirm the feasibility of the TER mechanism and indicate an ultrahigh TER ratio exceeding 9.9*10^10% of the proposed nanotube ferroelectric tunnel junctions. Our findings provide a promising approach based on simple homogeneous structures for high density ferroelectric microelectronic devices with excellent ON/OFF performance.Comment: 15 pages, 5 figure

    Shearing and Mixing Performance of Ultrahigh-Molecular-Weight Hydrolyzed Polyacrylamide (HPAM) Solution in a Helixes Static Mixer

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    Static mixers have been widely used to dilute high viscosity, high-molecular-weight polymer mother liquor for polymer flooding, in which the mixing performance plays a critical role. In this work, a novel mixing configuration, named as Helixes static mixer, was proposed to reduce high viscosity degradation rate of polyacrylamide solution resulting from mechanical shear during mixing process. Computational fluid dynamics simulations along with experiments were performed to investigate the mixing process. Several criteria such as the intensity of segregation, mixing distance, pressure loss, and shear strain rate were used to evaluate the mixing and shear performance of static mixers. Compared to the SMX and Kenics static mixer, a longer mixing distance is needed for the Helixes static mixer to achieve an ideal mixture. A lower shear strain rate along with less viscosity degradation rate is obtained in flow field of Helixes static mixer. The spiral-lead and helical directions of mixing elements were optimized to improve mixing performance. Experimental results are in good agreement with the numerical simulations on the intensity of segregation. The viscosity degradation rate of HPAM solution which flows through Helixes static mixer is lower than that of SMX and Kenics static mixers

    catena-Poly[[[tetra­aqua­manganese(II)]-μ-4,4′-bipyridine] bis­(3-hydroxy­cinnamate) dihydrate]

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    The title compound, {[Mn(C10H8N2)(H2O)4](C9H7O3)2·2H2O}n, was obtained by the hydro­thermal reaction of manganese chloride with mixed 3-hydroxy­lcinnamic acid (H2 L) and 4,4′-bipyridine (4,4′-bipy) ligands. The structure contains [Mn(C10H8N2)(H2O)4]2+ cations with the MnII atoms lying on a centres of inversion and bridged into a linear chain along the a axis by 4,4′-bipy ligands, surrounded by HL − anions and uncoordinated water mol­ecules. Extensive O—H⋯O hydrogen-bonding and weak π–π inter­actions [centroid–centroid distance = 3.7572  (3) Å] between the constituents lead to the formation of a three-dimensional supra­molecular network
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