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The study of multiple explosion resistance in offshore platform is important in the rescues of life and equipment. To evaluate residual anti-explosion performance of blast wall, numerical investigations are conducted suffering twice sequential blasts. Then comparison with analytical results under the single blast with the same impulse load is implemented. Results show that different from the single blast, the blast wall is bent as a fold after the second blast. There are three kinds of plastic hinge after the second blast due to the latent plastic hinge caused by the first blast. The prediction of residual ultimate resistance shows that additional plastic hinges strengthen the anti-explosion capability. The second blast evaluation is instructive to reinforce the structure and to set the passive plastic hinges

In this study, algae and microcystins (MC-LR and MC-RR) were studied in 6 reservoirs in the northeastern part of Haihe River Basin. The results indicate that the eutrophication degree of most reservoirs has been obviously improved, but Yuqiao reservoir and Yanghe reservoir are still in the state of eutrophication. The MC-LR and MC-RR were also detected in Yuqiao reservoir and Yanghe reservoir. In addition, cyanobacteria were dominant spices in the eutrophic reservoirs, and the concentration of microcystins was positively correlated with algae density. Although the concentration of MC-LR is lower than the concentration limits of sanitary standard for drinking water. It is suggested that it should be monitored during the outbreak of cyanobacteria, especially in the later stage of outbreak considering a risk for the health of the water supply population.

In this paper, the (TiB2+ZrB2)/AlSi9Cu1 composites were fabricated via in-situ reaction from Al-K2TiF6-K2ZrF6-KBF4 reaction system. The effects of rolling on microstructures and properties of the composites were investigated by XRD, SEM, TEM and mechanical tensile test. In addition, the influence mechanisms of plastic deformation on aluminum alloy composites were discussed in detail. The results show that the in-situ TiB2 and ZrB2 particle well distributed in the matrix with the size of 20~50 nm and the morphology is short-stick or plate. The rolling technology could obviously optimize the microstructure, enhance the properties of the composite especially, after 6 passes hot rolling and 4 passes cold rolling, the TiB2 and ZrB2 particles clusters with size range from 80 to 150 nm were uniformly distributed in the matrix, the Si phases were fractured into different small parts with the size of less than 1 μm and the grains size were further reduced. The ultimate tensile strength (UTS) and elongation (EL) of in-situ composite are 282MPa, 17.6%, respectively. Also, the Portevin-Le Chatelier (PLC) phenomenon found in the composite was discussed.

A non-intrusive method is proposed in this study with details showing the steps to convert rail pad into a load sensor for train wheel damage detection applications. The fabrication process is simple, requiring only the addition of a thin PVDF-based multilayered sensing device (approximately 0.7 mm) beneath the rail pad. An alternating-strip configuration is adopted in the multilayered sensing device, comprising active strips for sensing the vertical forces acting on the rail pad and dummy strips for resisting the potential lateral forces together with the baseplate shoulder. To validate the performance of the proposed rail pad sensor, both laboratory and field tests have been conducted. The tests results highlight the feasibility and potential of the rail pad sensor for train wheel condition monitoring. Unlike conventional strain gauge-based wheel load monitoring system, the rail pad sensor does not have blind zone problem.

The effects of crack defects on electronic and magnetic properties of zigzag MoS2 nanoribbons are investigated systematically by first-principles calculations based on spin-polarized density functional theory. We find that not only the electronic and spin transport ability of zigzag MoS2 nanoribbons can be enhanced significantly by the armchair crack defects, but also their magnetism could be modulated flexibly by crack defects. Our study suggests that the introduction of crack defect is a feasible way to modulate the electronic and magnetic properties of zigzag MoS2 nanoribbons. We further propose that the crack defects may also provide a useful tool for improving the performance of devices.

Several samples collected from lakes, rivers and reservoirs in Haihe river basin of China were analyzed for 8 sulfonamide antibiotics by using solid-phase extraction and liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). All water samples were enriched with HLB extraction cartridges. The antibiotics were separated by gradient elution with methanol as the mobile phase adding 0.1% formic acid. The eluate was then analyzed by the mode of multiple reaction monitoring (MRM). The limits of detection (LOD) and quantification (LOQ) were 0.4-1.0 ng/L and 1.0-3.0 ng/L respectively. The method was used for the analysis of 13 samples from Haihe river basin in China. The results showed that sulfamethoxazole was present in all water samples with maximum concentration of 107.59 ng/L. Sulfadiazine was also frequently detected, concentrations ranging from 2.81 ng/L to 85.35 ng/L. Other sulfonamide antibiotics were not detected in most water samples, especially for those samples from drinking water resources.

The temporal and spatial distribution of PAHs in surface-water from the typical rivers of North China was investigated. PAHs in typical rivers ranged from n.d. to 1.98 ng/L. LMW PAHs (2 and 3-ring) were abundant in surface water with high detection frequencies in Beisanhe River, while HMW PAHs (4 and 6-ring) were abundant in Luanhe River. Specific PAHs with its ratios were measured in order to deduce the possible sources of PAHs contaminant. The results indicate that the PAHs were from combustion processes in Beisanhe River, while PAHs were from petroleum products in Luanhe River.

Using first-principles density functional theory calculations, we investigate the structure, stability, optical modes and electronic band gap of a distorted tetragonal MoS$_2$ monolayer (T'-MoS$_2$). Our simulated scanning tunnel microscopy (STM) images of T'-MoS$_2$ are dramatically similar with those STM images which were identified as K$_{x}$(H$_{2}$O)$_{y}$MoS$_{2}$ from a previous experimental study. This similarity suggests that T'-MoS$_2$ might have already been observed in experiment but was unexpectedly misidentified. Furthermore, we verify the stability of T'-MoS$_2$ from thermal, mechanical and dynamic aspects, by \emph{ab initio} molecular dynamics simulation, elastic constants evaluation and phonon band structure calculation based on density functional perturbation theory, respectively. In addition, we calculate the eigenfrequencies and eigenvectors of the optical modes of T'-MoS$_2$ at $\Gamma$ point and distinguish their Raman and infrared activity by pointing out their irreducible representations using group theory; at the same time, we compare the Raman modes of T'-MoS$_2$ with those of H-MoS$_2$ and T-MoS$_2$. Our results provide a useful guidance for further experimental identification and characterization of T'-MoS$_2$., Comment: 10 pages, 12 figures, 3 tables

We present electronic band structure, Gibbs free energy of formation, and electric field modulation calculations for silicane nanoribbons (NRs), i.e., completely hydrogenated or fluorinated silicene NRs, using density functional theory. We find that although the completely hydrogenated silicene (H-silicane) sheet in the chair-like configuration is an indirect-band-gap semiconductor, a direct band gap can be achieved in the zigzag H-silicane NRs by using Brillouin-zone folding. Compared to H-silicane NRs, the band gaps of completely fluorinated silicene (F-silicane) NRs reduce at least by half. For all silicane NRs considered here, the Gibbs free energy of formation is negative but shows different trends by changing the ribbon width for H-silicane NRs and F-silicane NRs. Furthermore, by analyzing the effect of transverse electric fields on the electronic properties of silicane NRs, we show that an external electric field can make the electrons and holes states spatially separated and even render silicane NRs self-doped. The tunable electronic properties of silicane NRs make them suitable for nanotechnology application.

We formulate the law of conversion between spin current and charge current in several classes of materials including ferromagnetic, paramagnetic and spin-orbit coupled systems. We find that the interpretation of spin current is highly non-trivial, and we have identified pure and composite spin currents. For an interfacial Rashba spin-orbit coupled Hamiltonian, we show that the spin transport is much closer to that in ferromagnets than in non-magnetic materials. In particular, we show that an in-plane charge current in layered structures will generate a pure spin current flowing perpendicular to the Rashba spin-orbit coupled interface, and vice versa. Application of the spin-charge current conversion in several experimental realizations is discussed.

This paper describes a proof-of-concept work on implementing a polycrystalline p+-SixGe1-x gate electrode in both n- and p-channel metal-oxide semiconductor field-effect-transistors (MOSFETs). The process utilised for the fabrication of the MOSFETs only involved the use of two photo-lithographic masks. The device metallisation was realised using a self-aligned silicide process. The SixGe1-x film, deposited by the in situ B doping technique with 45?at.% of Si and 55?at.% of Ge, was found to be degenerately doped with a resistivity of 1?m?cm. It has been shown that the p+-Si0.45Ge0.55 gate controlled both types (n- and p-channel) of well functioning transistors at about the same threshold voltages (absolute values). This symmetrically controlled transistor characteristics was anticipated, since the work function of the p+-Si0.45Ge0.55 film is known to be close to the mid-bandgap value of Si.