Ultrahydrophobicity of Polydimethylsiloxanes-Based Multilayered Thin Films

The formation of polydimethylsiloxanes (PDMSs)-based layer-by-layer multilayer ultrathin films on charged surfaces prepared from water and phosphate buffer solutions has been investigated. The multilayer films prepared under these conditions showed different surface roughness. Nanoscale islands and network structures were observed homogeneously on the multilayer film prepared from pure water solutions, which is attributing to the ultrahydrobic property of the multilayer film. The formation of nanoscale islands and network structures was due to the aggregation of PDMS-based polyelectrolytes in water. This work provides a facile approach for generating ultrahydrophobic thin films on any charged surfaces by PDMS polyelectrolytes

Myrica rubra Extracts Protect the Liver from CCl4-Induced Damage

The relationship between the expression of mitochondrial voltage-dependent anion channels (VDACs) and the protective effects of Myrica rubra Sieb. Et Zucc fruit extract (MCE) against carbon tetrachloride (CCl4)-induced liver damage was investigated. Pretreatment with 50 mg kg−1, 150 mg kg−1 or 450 mg kg−1 MCE significantly blocked the CCl4-induced increase in both serum aspartate aminotransferase (sAST) and serum alanine aminotransferase (sALT) levels in mice (P < .05 or .01 versus CCl4 group). Ultrastructural observations of decreased nuclear condensation, ameliorated mitochondrial fragmentation of the cristae and less lipid deposition by an electron microscope confirmed the hepatoprotection. The mitochondrial membrane potential dropped from −191.94 ± 8.84 mV to −132.06 ± 12.26 mV (P < .01) after the mice had been treated with CCl4. MCE attenuated CCl4-induced mitochondrial membrane potential dissipation in a dose-dependent manner. At a dose of 150 or 450 mg kg−1 of MCE, the mitochondrial membrane potentials were restored (P < .05). Pretreatment with MCE also prevented the elevation of intra-mitochondrial free calcium as observed in the liver of the CCl4-insulted mice (P < .01 versus CCl4 group). In addition, MCE treatment (50–450 mg kg−1) significantly increased both transcription and translation of VDAC inhibited by CCl4. The above data suggest that MCE mitigates the damage to liver mitochondria induced by CCl4, possibly through the regulation of mitochondrial VDAC, one of the most important proteins in the mitochondrial outer membrane

A Method for Generation Phage Cocktail with Great Therapeutic Potential

Background: Bacteriophage could be an alternative to conventional antibiotic therapy against multidrug-resistant bacteria. However, the emergence of resistant variants after phage treatment limited its therapeutic application. Methodology/Principal Findings: In this study, an approach, named ‘‘Step-by-Step’ ’ (SBS), has been established. This method takes advantage of the occurrence of phage-resistant bacteria variants and ensures that phages lytic for wild-type strain and its phage-resistant variants are selected. A phage cocktail lytic for Klebsiella pneumoniae was established by the SBS method. This phage cocktail consisted of three phages (GH-K1, GH-K2 and GH-K3) which have different but overlapping host strains. Several phage-resistant variants of Klebsiella pneumoniae were isolated after different phages treatments. The virulence of these variants was much weaker [minimal lethal doses (MLD).1.3610 9 cfu/mouse] than that of wild-type K7 countpart (MLD = 2.5610 3 cfu/mouse). Compared with any single phage, the phage cocktail significantly reduced the mutation frequency of Klebsiella pneumoniae and effectively rescued Klebsiella pneumoniae bacteremia in a murine K7 strain challenge model. The minimal protective dose (MPD) of the phage cocktail which was sufficient to protect bacteremic mice from lethal K7 infection was only 3.0610 4 pfu, significantly smaller (p,0.01) than that of single monophage. Moreover, a delayed administration of this phage cocktail was still effective in protection against K7 challenge. Conclusions/Significance: Our data showed that the phage cocktail was more effective in reducing bacterial mutatio

Research on the in-situ stress inversion method of mine based on GA-BP algorithm

In-situ stress is the basis for designing mine roadway supports. Firstly, based on the GA-BP algorithm, establish a numerical analysis model, apply orthogonal tests, to establish the relationships between in-situ stress and lateral pressure coefficient, different rock parameters. Then, the optimization model is built by setting the sum of squares difference between measured and calculated in-situ stresses as optimization targets. Finally, using the model to solve the in-situ stress. Results show that the relative error between GABP algorithm inversion results and measured values is 2.9% averagely, while the relative error between BP algorithm inversion results and measured values is 4.4% averagely. Inversion methods can provide reference for similar mine in-situ stress inversion

Mechanical response of kerogen at high strain rates

As the main organic component of shale, the kerogen has a direct impact on the shale reservoirs. A molecular aggregate is used to study mechanical behaviour of kerogen, of which the molecular weight distribution is rational conforming to the Gaussian distribution. The mechanical response of kerogen is obtained with different strain rates by using molecular dynamics simulations. The results show that kerogen shows material hardening and fracture strain decrease with the strain rate. In the plastic range, we analyse the causes of stress oscillation at the microscopic level, and obtain the relationship between the stress oscillation and hydrogen bond. A compressible hyper-viscoelastic constitutive model of kerogen is established, which describes the mechanical behaviour of kerogen with different strain rates. Our research provides a valuable insight in the kerogen properties, and helps to understand the mechanical behaviour of shale reservoirs from a micro-perspective

Dual-polarized antenna design integrated with metasurface and partially reflective surface for 5G communication

A design of electrical down-tilt dual-polarized base station antenna array (BSAA) for 5G communication applications is presented in this paper, which is realized by integrating with reconfigurable reflective metasurface and partially reflective surface (PRS). By controlling the varactor diodes which are inserted into the reflective elements, we can adjust the mainlobe direction of BSAA. Moreover, the PRS over the array is utilized to construct Fabry-Perot (FP) cavity with reflective metasurface and ground plane. Based on this design approach, a 1 × 6 dual-polarized BSAA operating from 3.4 GHz to 3.6 GHz is designed and fabricated. Simulated and measured results show that the gain is enhanced about 2.56 dB by PRS while side lobe level (SLL) is less than −20 dB. The mainlobe of the antenna array can be adjusted accurately within ±5° for beam down-tilt. The cross polarization discrimination (XPD) is less than −40 dB

Spontaneous Motion and Rotation of Acid Droplets on the Surface of a Liquid Metal

Self-propulsion of droplets is of great significance in many fields. The spontaneous horizontal motion and self-jumping of droplets have been well realized in various ways. However, there is still a lack of an effective method to enable a droplet to rotate spontaneously and steadily. In this paper, by employing an acid droplet and a liquid metal, the spontaneous and steady rotation of droplets is achieved. For an acid droplet, it may spontaneously move when it is deposited on the surface of the liquid metal. By adjusting experimental parameters to the proper range, the self-rotation of droplet happens. This phenomenon originates from the fluctuation of the droplet boundary and the collective movement of bubbles that are generated by the chemical reactions between the acid droplet and liquid metal. This rotation has a simpler implementation method and more steady rotation state. Its angular velocity is much higher than that driven by other mechanisms. Moreover, the movements of acid droplets on the liquid metal are classified according to experimental conditions. The internal flow fields, the movements and distribution of bubbles, and the fluctuation of the droplet boundary are also explored and discussed. The theoretical model describing the rotational droplet is given. Our work may deepen the understanding of the physical system transition affected by chemical reactions and provide a new way for the design of potential applications, e.g., micro- and nanodevices

Swelling Mechanism of Core-Shell Polymeric Nanoparticles and Their Application in Enhanced Oil Recovery for Low-Permeability Reservoirs

Nanotechnology provides potential benefits for enhanced oil recovery (EOR) in low-permeability reservoirs. In this paper, SiO2/P(MBAAm-co-AM) composite nanoparticles were prepared using the distillation precipitation polymerization method. Scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis were employed to characterize the morphology and microstructure of nanoparticles. The swelling behavior of polymeric nanoparticles in brine was investigated to evaluate the effect of salinity and temperature. Kinetic and thermodynamic analyses were employed to reveal the swelling mechanism. Displacement experiments were performed to investigate their performance in EOR in low-permeability reservoirs. The results show that the swelling ratio of SiO2/P(MBAAm-co-AM) composite nanoparticles is higher at low salinity and high temperature, which can be explained by the Flory theory. The swelling process is spontaneous and endothermic, being controlled by physical adsorption involving the diffusion of water molecules, which complies with the first-order kinetics model. The suspension of SiO2/P(MBAAm-co-AM) composite nanoparticles can improve incremental oil recovery from 10.28 to 21.97% with an increase of the swelled particle size from 580 to 1160 nm. It is feasible that core-shell polymeric nanoparticles can be used for EOR in low-permeability reservoirs

Static and Dynamic Analysis of Conductor Rail with Large Cross-Sectional Moment of Inertia in Rigid Catenary Systems

The rigid catenary system is widely used in tunnels to power electric trains via contact with a pantograph. Due to gravity, the contact wire normally has a sag that may affect the dynamic interaction performance with a pantograph. To reduce the contact wire sag, the most efficient measure is to improve the moment of inertia of the conductor rail, which is used to clamp the contact wire. Six new types of conductor rail with large moments of inertia are developed based on a conventional conductor rail. Then both the static and dynamic analyses are conducted to investigate the performance of the new types of conductor rail with a big moment of inertia. The conductor rail’s 3D solid finite element model is built using a finite element approach. The vertical deflection and the stress distribution are comparatively analyzed among different types of conductor rail. The analysis results indicate that the vertical deflection and maximum stress are significantly reduced when using the conductor rail with a large moment of inertia. The best performance is observed when the conductor rail of case 1 is used. The maximum sag is reduced by 28.37%, and the maximum stress is decreased by 27.76% compared with the conventional conductor. Finally, a pantograph model is included to evaluate the dynamic performance of the conductor rail with large moments of inertia. The results indicate that contact force fluctuation is significantly reduced after the conductor rails with large moments of inertia are presented. The conductor rail of case 1 shows the best performance, which can reduce the contact force standard deviation by 32% and 27% at speeds of 160 km/h and 200 km/h