Synthesis of Semiconducting 2H-Phase WTe2 Nanosheets with Large Positive Magnetoresistance.

Tungsten ditelluride (WTe2) is provoking immense interest because of its unique electronic properties, but studies about its semiconducting hexagonal (2H) phase are quite rare. Herein, we report the synthesis of semiconducting 2H WTe2 nanosheets with large positive magnetoresistance, for the first time, by a simple lithium-intercalation-assisted exfoliation strategy. Systematic characterizations including high-resolution transmission electron microscopy, X-ray diffraction, and Raman and X-ray photoelectron spectroscopies provide clear evidence to distinguish the structure of 2H WTe2 nanosheets from the orthorhombic (Td) phase bulk counterpart. The corresponding electronic phase transition from metal to semiconductor is also confirmed by density of states calculation, optical absorption, and electrical transport property measurements. Besides, the 2H WTe2 nanosheets exhibit large positive magnetoresistance with values of up to 29.5% (10 K) and 16.2% (300 K) at 9 T. Overall, these findings open up a promising avenue into the exploration of WTe2-based materials in the semiconductor field.

Calculation model and experimental study of the collapse strength of titanium alloy tubing and casing.

Titanium alloy has become a promising candidate material for oil country tubular goods (OCTGs) in harsh service environments owing to its high specific strength, low density, low elastic modulus, excellent toughness, excellent anti-fatigue and corrosion resistance. However, because the high-quality natural gas resources in China are mainly concentrated deep underground, titanium alloy tubing and casing will bear great external pressure loads underground, so the collapse strength of titanium alloy tubing and casing is very important for the safety of the string in the well. In this paper, a new collapse strength calculation model, the strength collapse criterion model (SCM), was proposed for titanium alloy tubing and casing. 35 different specifications of titanium alloy tubing and casing were selected for the full-scale collapse tests to verify the reliability of the established SCM model. Furthermore, the effect of different key parameters (such as strength, ovality, eccentricity and residual stress) on collapse strength of titanium alloy pipes were investigated systematically and compared with the same specifications of steel pipes. The strength collapse criterion model and analysis results can provide a technical reference for the design and use of titanium alloy OCTGs in the petroleum and natural gas industries.

[In-situ DRIFTS study of coupling partial oxidation of methane and carbon dioxide reforming].

8%Ru-5%Ce/gamma-Al2O3 catalyst exhibited excellent catalytic performance for low temperature activation of methane. Although the conversion rates of methane were 25.3% for exothermal partial oxidation of methane, and 0.8% for endothermal carbon dioxide reforming, whose activity was rather low, 38.8% of conversion rate of methane could be obtained for the obtained coupling reaction at 500 degrees C owing to the coupling intensification between endothermal carbon dioxide reforming reaction and exothermal partial oxidation of methane. The mechanism of coupling partial oxidation of methane and carbon dioxide reforming on supported Ru catalyst was investigated by in-situ DRIFTS. The adsorption of CO on 8%Ru-5%Ce/gamma-Al2O3 showed that two kinds of doublet peaks which were characteristic adsorption of the gaseous CO at 2167 cm(-1) (2118 cm(-1)) to form Ru(CO)2 at 2031 cm(-1) (2034 cm(-1)) to form Ce(CO)2 were observed. These CO adsorption species wee easy to be desorbed from the surface of the catalyst at high temperature. The results of in-situ DRIFTS showed that carbonate, formal (formate) and carbon monoxide formed on the surface of catalyst, and formal (formate) was intermediate for the methane partial oxidation. This intermediate was formed through the combination of the adsorption species of methane CHx and the lattice oxygen adsorption species on the surface of catalyst, and syngas was produced through the splitting of this intermediate. The DRIFTS researching on carbon dioxide reforming showed that there was no new adsorption species on the surface of the catalyst, which indicated that the mechanism for carbon dioxide reforming was through the dissociation of the adsorbed methane and carbon dioxide. During the reaction of the coupling of carbon dioxide reforming reaction and partial oxidation of methane, there was hydroxyl adsorption species on the surface of catalyst. The mechanism of coupling methane, carbon dioxide and oxygen might be composed of the above two reaction mechanism and the bridging hydroxyl group adsorption species Ru-(OH)2 might contribute to the coupling reaction.

Hierarchical porous activated biochar derived from marine macroalgae wastes (Enteromorpha prolifera): facile synthesis and its application on Methylene Blue removal.

Biochar is one of the most promising candidates of the cost-effective adsorbent for wastewater treatment. Herein, a novel hierarchical porous activated biochar derived from Enteromorpha prolifera (EPAC) was synthesized via an oily sludge-assisted "one-step" carbonization and activation approach. The results proved that the oily sludge additive acts as a natural structure directing agent during the EPAC preparation. The resultant EPAC possesses favorable properties such as high surface area and hierarchical pore distribution, which bring about its outstanding adsorption capability (910 mg g-1) for Methylene Blue dyes from wastewater. The adsorption kinetics, isotherms, thermodynamics and the effect of pH and the background ionic species on the adsorption process were investigated. The adsorption data could be well illustrated by Langmuir models and pseudo-second-order models. Furthermore, thermodynamic parameters revealed that the adsorption reaction was an endothermic and spontaneous process. The adsorption process was influenced by the solution pH and background ionic species because of the competitive adsorption. Moreover, the regeneration analysis demonstrates a presentable recyclability of the EPAC. In view of its good adsorption performance, the EPAC prepared in this study has the potential of treating dye wastewater in practical applications.

Immune responses of orange-spotted grouper, Epinephelus coioides, against virus-like particles of betanodavirus produced in Escherichia coli.

Betanodaviruses are the causative agents of viral nervous necrosis (VNN), a serious disease of cultured marine fish worldwide. Virus-like particles (VLPs) are one of the good novel vaccine candidates to control this disease. Until now, betanodavirus vaccine studies mainly focused on the humoral immune response and mortality after virus challenge. However, little is known about the activation of genes responsible for cellular and innate immunity by vaccines. In the present study, VLPs of orange-spotted grouper nervous necrosis virus (OGNNV) were produced in prokaryotes and their ability to enter Asian sea bass cells was the same as native virus, suggesting that they possess a similar structure to OGNNV. VLPs immunogenicity was then determined by intramuscularly vaccinating Epinephelus coioides at different concentrations (1.5 or 15 µg g(-1) fish body weight, FBW) and immunizing frequencies (administration once, twice and thrice). A single vaccination with the dosage of 1.5 µg g(-1) FBW is enough to provoke high titer antibodies (average 3 fold higher than that of negative control) with strong neutralizing antibody titer as early as 1 week post immunization. Furthermore, quantitative PCR analysis revealed that eleven genes associated with humoral, cellular and innate immunities were up-regulated in the liver, spleen and head kidney at 12h post immunization, correlating with the early antibody response. In conclusion, we demonstrated that VLP vaccination induced humoral immune responses and activated genes associated with cellular and innate immunity against betanodavirus infection in orange-spotted grouper.

Genome-wide analyses of proliferation-important genes of Iridovirus-tiger frog virus by RNAi.

Tiger frog virus (TFV), a species of genus Ranavirus in the family Iridoviridae, is a nuclear cytoplasmic large DNA virus that infects aquatic vertebrates such as tiger frog (Rana tigrina rugulosa) and Chinese soft-shelled turtle (Trionyx sinensis). Based on the available genome sequences of TFV, the well-developed RNA interference (RNAi) technique, and the reliable cell line for infection model, we decided to analyze the functional importance of all predicted genes. Firstly, a relative quantitative cytopathogenic effect (Q-CPE) assay was established to monitor the viral proliferation in fish cells. Then, genome-wide RNAi screens of 95 small interference (si) RNAs against TFV were performed to characterize the functional importance of nearly all (95%) predicted TFV genes by Q-CPE scaling system. We identified 32 (33.7%) genes as essential, 50 (52.6%) genes as semi-essential and 13 (13.7%) genes as nonessential for TFV proliferation. Quantitative RT-PCR and titer assays of selected genes were performed to verify the screen results. Furthermore, the screened essential genes were analyzed for their genome distribution and conservative comparison within Ranavirus. Such a systematic screen for viral functional genes by cell phenotypes should provide further insights into understanding of the information in antiviral targets, and in viral replication and pathogenesis of iridovirus.

The viral TRAF protein (ORF111L) from infectious spleen and kidney necrosis virus interacts with TRADD and induces caspase 8-mediated apoptosis.

Infectious spleen and kidney necrosis virus (ISKNV) is the type species of the Megalocytivirus genus of the Iridoviridae family. It causes a serious and potentially pandemic disease in wild and cultured fishes. ISKNV infection induces evident apoptosis in mandarin fish (Siniperca chuatsi) and zebrafish (Danio renio). However, the mechanism is still unknown. After a genome-wide bioinformatics analysis of ISKNV-encoded proteins, the ISKNV open reading frame 111L (ORF111L) shows a high similarity to the tumour necrosis factor receptor-associated factor (TRAF) encoded by fish, mice and mammals, which is essential for apoptotic signal transduction. Moreover, ORF111L was verified to directly interact with the zebrafish TNF receptor type 1 associated death domain protein (TRADD). A recombinant plasmid containing the DNA sequence of ORF111L was constructed and microinjected into zebrafish embryos at the 1-2 cell stage to investigate its biological function in vivo. ORF111L overexpression in the embryos resulted in increased apoptosis. ORF111L-induced apoptosis was clearly associated with significant caspase 8 upregulation and activation. The knockdown of zebrafish caspase 8 expression effectively blocked the apoptosis induced by ORF111L overexpression. Significantly, ORF111L overexpression resulted in much stronger effect on caspase 8 and caspase 3 upregulation compared to zebrafish TRAF2. This is the first report of a viral protein similar to TRAF that interacts with TRADD and induces caspase 8-mediated apoptosis, which may provide novel insights into the pathogenesis of ISKNV infection.

Two Litopenaeus vannamei HMGB proteins interact with transcription factors LvSTAT and LvDorsal to activate the promoter of white spot syndrome virus immediate-early gene ie1.

White spot syndrome virus (WSSV) has caused great economic damage to shrimp aquaculture. Previous studies have shown that WSSV successfully usurps the immunity system of the host for its own gene regulation. To investigate the role of shrimp high mobility group box (HMGB) proteins in WSSV gene regulation, two Litopenaeus vannamei HMGB genes, LvHMGBa and LvHMGBb, were isolated by rapid amplification of cDNA ends (RACE). Recombinant LvHMGBa/b proteins were present in the nucleus of transfected Drosophila Schneider 2 (S2) cells. Luciferase reporter assays revealed that LvHMGBa/b upregulated the WSSV immediate-early (IE) gene (ie1) in a NF-κB and STAT binding site-dependent manner. GST pull-down assays demonstrated that LvHMGBa/b interacted with L. vannamei Dorsal (LvDorsal) and L. vannamei STAT (LvSTAT), respectively. LvHMGBa was highly expressed in hepatopancreas while HMGBb was highly expressed in stomach, intestine, heart, antennal gland, and epidermis. Moreover, an immune challenge assay demonstrated that the expression of LvHMGBa/b was upregulated by WSSV infection and that both mRNAs reached peak values at 24 h post-infection. To our knowledge, this is the first report that invertebrate HMGB proteins participates in viral gene regulation.

[The expression of Aeromonas hydrophila ompTS gene and the immunogenicity of recombinant OmpTS].

Primers were designed based on ompTS gene reported recently. With the specific primers, one target fragment about 1024 bp lacking the signal sequence of ompTS gene was amplified from A. hydrophila genomic DNA via PCR. The ompTS gene was hyperexpressed using gene fusion expression vector pRSET system, and the recombinant OMP exhibited a size of 39.9 kD with SDS-PAGE and Western blot analysis, which showed about 51% of total lysate proteins. Antibody to the purified recombinant OMP reacted not only to the recombinant OMP but also to the purified OMPs from A. hydrophila in ELISA and the 36.9 kD OMP in Western blot. The result indicates that the recombinant OMP has the same epitope with the nature one.