Reliability of a System Having Quasi-Redundancy

Reliability mathematical models of a certain type of system with a branching configuration, possessing quasi-redundant properties, are developed for the nonrepair environment. A simple system of this type is chosen as a vehicle to illustrate the method of approach when in a repair environment. To solve the simultaneous differential equations for such a system in a repair environment, analog computer simulation is found to be very suitable.     

Electron beam irradiation of zinc borate flame retardant containing acrylonite-butadiene-styrene (ABS) composites

The effects of electron beam radiation and zinc borate on the mechanico-physical properties and flame resistivity of magnesium hydroxide (MOH)- acrylonitrile butadiene styrene (ABS) composites have been investigated. The increasing of irradiation dosages has gradually improved the tensile strength and gel content of all samples by inducing the degree of crosslinking networks formed in ABS matrix. Analysis shows that higher amount of zinc borate is desirable to achieve promising tensile strength because zinc borate can attach into the interfaces between MOH particles and ABS matrix. Moreover, the addition of zinc borate could also retard the flammability of ABS as evidenced by LOI results. The crosslinking networks formed could improve fire resistance by reducing the melt dripping phenomenon. This is expected because the crosslinking networks can effectively minimize the oxygen gas to penetrate through the polymer structure to participate actively in the combustion activity.     

Electroconductive and catalytic performance of polypyrrole/montmorillonite/silver composites synthesized through in situ oxidative polymerization

The present study demonstrates a simple approach to the formation of polypyrrole/montmorillonite/silver (PPy/Mt/Ag) composites via in situ oxidative polymerization of pyrrole (Py) in the presence of AgNO₃ acting as a direct oxidant. The polymerization was performed in the presence of dodecylbenzenesulfonic acid, which acts as a stabilizing and doping agent. The morphological, structural, and thermal properties of PPy/Mt/Ag composites are discussed in detail and a possible formation mechanism is proposed. The electrical conductivities of the composites pressed at different pressing pressures were investigated using four‐probe analyzer. X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy results indicated the partially exfoliated structure of the composites and Fourier transforms infrared results suggested the strong interactions between Si? O? Si groups in Mt and N? H groups in PPy chains. The addition of Mt in the PPy polymer enhanced thermal property of the polymer. The conductivity of 1.08 S cm^?1 was observed in the sample with 20 wt % Mt loading and applied pressure of 5 MPa. The composites obtained in the present study catalyze the reduction of methylene blue by sodium borohydride, achieving 92% conversion of MB to colorless within a few minutes. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45986.     

Game theory‐based global optimization for inter‐WBAN interference mitigation

Researchers' attempts to monitor and collect environmental data have led to the emergence of Wireless Sensor Networks (WSNs). In light of WSN, the monitoring target has been changed recently from the environment to the human or animal body: sensor nodes are placed on, in, or around the body to gather biosignals, which will be stored by a wearable sink node. But, WSN has an important problem, that is, the coverage problem, which may generate interference signals and influence system reliability during data transmission. Some biosignals are very important. The reduction of system reliability due to high latency or packet loss may result in significant loss of important data and can be life‐threatening (A patient's heartbeat or breathing stops but no staff receives the medical alerts). For this reason, this study makes use of a cooperative non‐zero‐sum game model for controlling the transmit power of the system as well as reducing the obstructions between simultaneous transmissions and avoiding contention between messages. In our simulated scenario, every WBAN is a regarded as a node. To avoid the situation that any one of the sensors stops running, this study further includes a global optimization technique to cover all nodes in the game and improve the time difference of sensors' lifetime. Copyright © 2017 John Wiley & Sons, Ltd.     

强场物理中超热电子能量沉积特性的实验研究

报道了在100 Tw超短脉冲掺钛蓝宝石激光装置上,完成的飞秒激光-固体靶相互作用中超热电子的能量沉积实验,获得了靶后激光传播方向超热电子的能谱、产额、注量和总能量.结果表明,超热电子的注量和总能量随靶厚的增加而减少,超热电子约80%的能量主要沉积在靶内的前10μm,分析其原因是由于静电场的影响所致.     

Cholic Acid-Based Antimicrobial Peptide Mimics as Antibacterial Agents

There is a significant and urgent need for the development of novel antibacterial agents to tackle the increasing incidence of antibiotic resistance. Cholic acid-based small molecular antimicrobial peptide mimics are reported as potential new leads to treat bacterial infection. Here, we describe the design, synthesis and biological evaluation of cholic acid-based small molecular antimicrobial peptide mimics. The synthesis of cholic acid analogues involves the attachment of a hydrophobic moiety at the carboxyl terminal of the cholic acid scaffold, followed by the installation of one to three amino acid residues on the hydroxyl groups present on the cholic acid scaffold. Structure–activity relationship studies suggest that the tryptophan moiety is important for high antibacterial activity. Moreover, a minimum of +2 charge is also important for antimicrobial activity. In particular, analogues containing lysine-like residues showed the highest antibacterial potency against Gram-positive S. aureus. All di-substituted analogues possess high antimicrobial activity against both Gram-positive S. aureus as well as Gram-negative E. coli and P. aeruginosa. Analogues 17c and 17d with a combination of these features were found to be the most potent in this study. These compounds were able to depolarise the bacterial membrane, suggesting that they are potential antimicrobial pore forming agents.     

Sevoflurane Induces Neurotoxicity in the Animal Model with Alzheimer’s Disease Neuropathology via Modulating Glutamate Transporter and Neuronal Apoptosis

Perioperative neurocognitive disorders are frequently observed in postoperative patients and previous reports have shown that pre-existing mild cognitive impairment with accumulated neuropathology may be a risk factor. Sevoflurane is a general anesthetic agent which is commonly used in clinical practice. However, the effects of sevoflurane in postoperative subjects are still controversial, as both neurotoxic or neuroprotective effects were reported. The purpose of this study is to investigate the effects of sevoflurane in 3 × Tg mice, a specific animal model with pre-existing Alzheimer’s disease neuropathology. 3 × Tg mice and wild-type mice were exposed to 2 h of sevoflurane respectively. Cognitive function, glutamate transporter expression, MAPK kinase pathways, and neuronal apoptosis were accessed on day 7 post-exposure. Our findings indicate that sevoflurane-induced cognitive deterioration in 3 × Tg mice, which was accompanied with the modulation of glutamate transporter, MAPK signaling, and neuronal apoptosis in the cortical and hippocampal regions. Meanwhile, no significant impact was observed in wild-type mice. Our results demonstrated that prolonged inhaled sevoflurane results in the exacerbation of neuronal and cognitive dysfunction which depends on the neuropathology background.     

低品位氧化锑矿回收新工艺研究与应用

木利锑业有限公司下属选矿厂的尾矿含锑1．55％,其中硫化锑矿物占46．45％,对其进行详细的浮选条件试验,并对浮选尾矿进行重选回收锑试验研究,最终获得较好的指标。在试验基础上,根据选矿厂的实际进行了流程改造。将新工艺应用于生产,使选矿厂锑回收率提高8％,企业增加效益并使资源得到充分利用。     

Effect of Cr and Ni/Fe Ratio on the Microstructure and Mechanical Properties of γ′-Strengthened Ni–Fe-Based Alloys

Metallurgical and Materials Transactions A - To continue to meet the future materials’ requirements for advanced power generation systems, enhancing the mechanical properties and long-term...