[en] Highlights: • No work on heat treatment have been discussed for hot-hydrostatically extruded alloy. • Precipitations have been discussed in detail for the alloy by TEM. • Main strengthening mechanisms have been analyzed. - Abstract: Microstructure, mechanical properties and strengthening mechanisms of tungsten heavy alloys consolidated by liquid-phase sintered, hot-hydrostatic extrusion and heat treatment were investigated. The results showed that ultimate tensile strength σ_b of 93W-4.9Ni-2.1Fe alloy with area reduction 75% extruded at 1200 °C could reach as high as about 1540 MPa and elongation could also reach 9.2%. Meanwhile, ultimate tensile strength and elongation by heat treatment remain 1487 MPa and 13.4%, respectively. Transmission electron microscopy observation revealed that as-extruded alloys were characterized by fine subgrains in elongated tungsten grains and dynamically re-crystallized grains in Ni-Fe-W matrix phase. Tungsten subgrains subsequently grew up a bit and nanocrystalline W with most of them being less than 100 nm in length showing a needle precipitated in Ni-Fe-W matrix phase after heat treatment at 1000 °C for 1 h. Results indicate that one of the strengthening mechanisms is interface strengthening between tungsten and matrix phase due to severe plastic deformation, which can be explained via aspect ratio correlated with deformed tungsten particles. The other strengthening mechanism can be attributed to precipitated nanocrystalline W during heat treatment in Ni-Fe-W matrix phase of the as-extruded alloy with area reduction 75%

[en] Highlights: • UV-B radiation showed higher inhibition to non-toxin producing than toxin-producing strains on growth and photosynthetic activity. • Both intracellular and extracellular MC contents decreased markedly under UV-B radiation. • Higher resistance to UV-B radiation helped toxin-producing M. aeruginosa to predominate in the competition. - Abstract: Microcystins (MCs) produced by toxic cyanobacteria pose a health hazard to humans and animals. Some environmental factors can alter the MC concentrations by affecting the abundance of toxin-producing strains in a cyanobacteria population and/or their toxin production. In this study, we designed a monoculture and competition experiment to investigate the impacts of UV-B radiation on MC production and the competition between toxin and non-toxin producing strains of Microcystis aeruginosa. UV-B radiation resulted in higher inhibition of the growth and photosynthetic activity of the non-toxin producing strain relative to that observed for the toxin-producing strain. Both intracellular and extracellular MC contents decreased markedly when the toxin-producing strain was exposed to UV-B radiation. In addition, a quantitative real-time PCR assay revealed that the ratio of toxin-producing M. aeruginosa under UV-B exposure was higher than that under PAR alone at an early stage of the experiment. However, its abundance under UV-B exposure was lower compared with the PAR alone treatment after day 12. Our study demonstrated that UV-B radiation has a great impact on the abundance of the toxin-producing strain in the Microcystis population and their toxin production, which suggests that the fluctuation of UV-B radiation affects the MC level of cyanobacteria blooms

[en] Some specific gene mutation plays an important role in the pathogenesis of human familial pheochromocytoma (FPCC) , however little is known about the possible role of molecular mutation patterns in FPCC development. We report the cancer and inherited diseases associated gene panels analysis of FPCC (isolated pheochromocytoma, confirmed by clinical examination), aiming to identify gene mutations specific to FPCC which may contribute to the disease development. The Ion AmpliSeq™Cancer Hotspot Panel v2 (designed to amplify 207 amplicons covering approximately 2,800 COSMIC mutations from 50 oncogenes and tumor suppressor genes) and Inherited Disease Panel (designed to amplify 10500 amplicons covering mutations for over 300 genes in over 700 unique inherited diseases, according to NCBI ClinVar database) analysis was performed using Ion Torrent PGM on peripheral blood DNA extracted from FPCC subjects (n=2, two patients of isolated pheochromocytoma from one family, father and his son), subjects with pheochromocytoma accompanying thyroid carcinoma (PCC-TC, n=2, from different family) and normal subjects (n=2, from different family). Gene mutations analysis was performed using Ion Reporter software. During the next generation sequencing work flow, strict quality control was carried out in DNA purification, library construction, template preparation and sequencing. All candidate gene mutation sites were confirmed by sanger sequencing. Comparison of FPCC with PCCTC and normal subjects identified 45 significant gene mutation positions, including 1 site of cancer associated gene and 44 sites of inherited diseases associated genes. 30 genes were found to have differential mutation patterns in FPCC compared with PCC-TC and normal subjects, including ABCA4, ACTA2, ANK2, CDH23, CFTR, CHAT, CLCN1, COL1A1, COL4A1, COL5A1, DNAH11, DNAH5, DNAH9, DSP, EYS, FANCF, FBN1, GJB3, IDUA, IKBKAP, JAG1, MYLK, PCDH15, PTCH1, RPGRIP1, SPG7, TBX5, USH2A, VCL and VHL. Above all, VHL 10183815 C>G heter mutation (codon 51, 284C>G, Pro95Arg, COSMIC 17699) has been confirmed in von Hippel-Lindau disease. This study is the comprehensive analysis of molecular mutation patterns of FPCC and identifies dozens of gene mutation positions as a potential novel biomarker during FPCC development. (author)

[en] Acryl amide (AAm) was grafted onto poly (vinylidene fluoride) (PVDF) powder by a γ-rays pre-irradiation induced graft polymerization technique. The DG values of the PVDF-g-PAM powder were determined by fluorine elemental analysis. Effects of grafting time on DG of PVDF-g-PAM powder at the same monomer concentration were studied. And modified powder was dissolved in NMP and added PVP as pre-forming agent. The microfiltration (MF) membranes were cast using a phase inversion method. The contact angle, degree of swelling, water flux and antifouling properties of those modified MF membranes were investigated. The results indicated that the hydrophilicity of modified MF membranes was improved obviously and the antifouling property of modified MF membranes (DG of 13%) was better than that of the pristine membrane. (authors)

[en] Quasi-classical trajectory calculations are performed to study the stereodynamics of the reaction based on the first excited state NH_2(1"2A′) potential energy surface reported by Li et al. [Li Y Q and Varandas A J C 2010 J. Phys. Chem. A 114 9644] for the first time. We observe the changes of differential cross-sections at different collision energies and different initial reagent rotational excitations. The influence of collision energy on the k–k′ distribution can be attributed to a purely impulsive effect. Initial reagent rotational excitation transforms the reaction mechanism from insertion to abstraction. The effect of initial reagent rotational excitations on k–k′ distribution can be explained by the rotational excitation enlarging the rotational rate of reagent NH in the entrance channel to reduce the probability of collision between incidence H atom and H atom of target molecular. We also investigate the changes of vector correlations and find that the rotational angular momentum vector j′ of the product H_2 is not only aligned, but also oriented along the y axis. The alignment parameter, the disposal of total angular momentum and the reaction mechanism are all analyzed carefully to explain the polarization behavior of the product rotational angular moment. (paper)

[en] We investigate atomic and electronic structures of boron nanotubes (BNTs) by using the density functional theory (DFT). The transport properties of BNTs with different diameters and chiralities are studied by the Keldysh nonequilibrium Green function (NEGF) method. It is found that the cohesive energies and conductances of BNTs decrease as their diameters decrease. It is more difficult to form (N, 0) tubes than (M, M) tubes when the diameters of the two kinds of tubes are comparable. However, the (N, 0) tubes have a higher conductance than the (M, M) tubes. When the BNTs are connected to gold electrodes, the coupling between the BNTs and the electrodes will affect the transport properties of tubes significantly

[en] The tensile mechanical properties and fracture behavior of 90W–7Ni–3Fe alloy have been investigated in the temperature range from 298 K to 1473 K. The results showed that the mechanical properties of the alloy were highly sensitive to temperature and decreased with increasing temperature in most cases. The maximum Rockwell hardness and higher ultimate tensile strength at 673 K explicated better work hardening ability. In addition, it was most likely that W grains refinement resulted in a significant increase of Vickers micro hardness at 1073–1473 K. Scanning Electron Microscopy (SEM) was used to observe the tensile fracture morphology. It was found that the fracture mechanisms of the alloy gradually evolved from a mixture of W cleavage fracture and matrix phase dimples at room temperature to a mixture of the interface separation of W/W particles and W/matrix at higher temperature. Additionally, when the temperature rose to 1473 K, the phenomenon of coarse matrix occurred. Suspiciously, the deteriorating mechanical properties at elevated temperatures was caused by the influence of the precipitation phase.

[en] In this study, compound plastic deformation technologies including canned extrusion and rotary swaging were developed to produce W-40 wt.% Cu composite. The relative density increases from 98.4% of as-extruded composite to 99.1% after swaging at 1223 K. The as-extruded composites have conductance of 67% IACS and hardness of 155 HV. But the as-extruded composites swaged at 1173 K ∼ 1323 K have higher hardness and lower specific conductance with accumulated deformation amount ∼72.30%. After heat treatment at 973 K ∼ 1273 K, the deformed material obtained a better match between the hardness and the conductivity. After compound plastic deformation, homogeneous microstructure of W and Cu phases for W-40 wt.% Cu composite can be acquired. All results indicate that W-40 wt.% Cu composite with high performance can be fabricated by compound plastic deformation technologies. (paper)

[en] The atomic and electronic structures of a graphene monolayer on a Ru(0001) surface under compressive strain are investigated by using first-principles calculations. Three models of graphene monolayers with different carbon periodicities due to the lattice mismatch are proposed in the presence and the absence of the Ru(0001) substrate separately. Considering the strain induced by the lattice mismatch, we optimize the atomic structures and investigate the electronic properties of the graphene. Our calculation results show that the graphene layers turn into periodic corrugations and there exist strong chemical bonds in the interface between the graphene N × N superlattice and the substrate. The strain does not induce significant changes in electronic structure. Furthermore, the results calculated in the local density approximation (LDA) are compared with those obtained in the generalized gradient approximation (GGA), showing that the LDA results are more reasonable than the GGA results when only two substrate layers are used in calculation. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

[en] High-resolution (sub-microsecond to nanosecond) time-resolved measurements of the dynamics of superconducting electronic devices, such as Josephson tunnel junctions and SQUIDs, are indispensable for fundamental physics research, such as quantum mechanics of macroscopic variables. We describe the development of a time-resolved measurement technique that enables direct measurements, in the time domain, of the temporal evolution of Josephson junctions with a nanosecond resolution. The technique was applied to study escape dynamics of Josephson junctions, as macroscopic quantum systems, in the quantum tunnelling regime. The measured probability of junctions remaining in the initial metastable state - the survival probability - as a function of time decayed exponentially, agrees very well with the theoretical prediction of the incoherent tunnelling process. (author)