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In the present study, we use direct numerical simulation to investigate the density-driven convection in a two-dimensional anisotropic heterogeneous porous media associated with significant laminated formation. At first, the heterogeneous porous media are randomly generated to represent laminated structure, in which the horizontal correlation length of permeability field is much longer than the vertical counterpart. Then, a highly accurate pseudo-spectral method and compact finite difference scheme with higher order of accuracy are employed to numerically reproduce the convection flow in the laminated porous media. The results show that the laminated structures restrict interactions among the downward plumes of heavier fluid. The plumes tend to descend more straightly in a laminated porous medium associated with a slower growth rate. As a result, the laminated distribution of permeability is considered having an inhibiting effect on the convection flow.
Distinguished by a marked combination of high strength and high fracture toughness, 18Ni-300 maraging steel (MS) is widely used for intricate tool and die applications. MS is also amenable to the powder bed fusion additive manufacturing process, providing unique opportunities to make small features and incorporate cooling channels in molds. In this study, tensile test samples were fabricated using selective laser melting to investigate the effects of built height and orientations on the evolution of the microstructure and the mechanical properties of the samples. The microstructure of the as-fabricated samples consists of the primary α-martensite phase and fine cellular microstructure (~0.66–0.83 μm) with the retained austenite γ-phase aggregated at the boundaries of the cells, resulting in an enhanced mechanical performance compared with traditional counterparts under the same condition (without post-heat treatments). Random grain orientations with weak textures are revealed in all samples. The XY-built samples display better tensile performance when compared to the Z-built samples due to the fine grain sizes and the retained γ phase. The bottom of the Z-built sample exhibits a higher hardness than other parts of the sample, which could be attributed to its finer cellular structure.
Cigarette smoking is strongly associated with major depressive disorder (MDD). However, any genetic etiology of such comorbidity and causal relations is poorly understood, especially at the genome-wide level.
In the present in silico research, we analyzed summary data from the genome-wide association study of the Psychiatric Genetic Consortium for MDD (n = 191 005) and UK Biobank for smoking (n = 337 030) by using various biostatistical methods including Bayesian colocalization analysis, LD score regression, variant effect size correlation analysis, and Mendelian randomization (MR).
By adopting a gene prioritization approach, we identified 43 genes shared by MDD and smoking, which were significantly enriched in membrane potential, gamma-aminobutyric acid receptor activity, and retrograde endocannabinoid signaling pathways, indicating that the comorbid mechanisms are involved in the neurotransmitter system. According to linkage disequilibrium score regression, we found a strong positive correlation between MDD and current smoking (rg = 0.365; p = 7.23 × 10−25) and a negative correlation between MDD and former smoking (rg = −0.298; p = 1.59 × 10−24). MR analysis suggested that genetic liability for depression increased smoking.
These findings inform the concomitant conditions of MDD and smoking and support the use of self-medication with smoking to counteract depression.
The family Tephritidae (order: Diptera), commonly known as fruit flies, comprises a widely distributed group of agricultural pests. The tephritid pests infest multiple species of fruits and vegetables, resulting in huge crop losses. Here, we summarize the composition and diversity of tephritid gut-associated bacteria communities and host intrinsic and environmental factors that influence the microbiome structures. Diverse members of Enterobacteriaceae, most commonly Klebsiella and Enterobacter bacteria, are prevalent in fruit flies guts. Roles played by gut bacteria in host nutrition, development, physiology and resistance to insecticides and pathogens are also addressed. This review provides an overview of fruit fly microbiome structure and points to diverse roles that it can play in fly physiology and survival. It also considers potential use of this knowledge for the control of economically important fruit flies, including the sterile insect technique and cue-lure baiting.
Some amino acids (AA) act through several signalling pathways and mechanisms to mediate the control of gene expression at the translation level, and the regulation occurs, specifically, on the initiation and the signalling pathways for translation. The translation of mRNA to protein synthesis proceeds through the steps of initiation and elongation, and AA act as important feed-forward activators that are involved in many pathways, such as the sensing and the transportation of AA by cells, in these steps in many tissues of mammals. For the translation, phosphorylation of eukaryotic translation initiation factor 2α (eIF2α) is a critical molecule that controls the translation initiation and its functions can be regulated by some AA. Another control point in the mRNA binding step in the translation initiation is at the regulation by mammalian target of rapamycin, which requires a change of phosphorylation status of ribosomal protein S6. In fact, the change of phosphorylation status of ribosomal protein S6 might be involved in global protein synthesis. The present review summarises recent work on the molecular mechanisms of the regulation of protein synthesis by AA and highlights new findings.
Starch digestion in the small intestines of the dairy cow is low, to a large extent, due to a shortage of syntheses of α-amylase. One strategy to improve the situation is to enhance the synthesis of α-amylase. The mammalian target of rapamycin (mTOR) signalling pathway, which acts as a central regulator of protein synthesis, can be activated by leucine. Our objectives were to investigate the effects of leucine on the mTOR signalling pathway and to define the associations between these signalling activities and the synthesis of pancreatic enzymes using an in vitro model of cultured Holstein dairy calf pancreatic tissue. The pancreatic tissue was incubated in culture medium containing l-leucine for 3 h, and samples were collected hourly, with the control being included but not containing l-leucine. The leucine supplementation increased α-amylase and trypsin activities and the messenger RNA expression of their coding genes (P <0.05), and it enhanced the mTOR synthesis and the phosphorylation of mTOR, ribosomal protein S6 kinase 1 and eukaryotic initiation factor 4E-binding protein 1 (P <0.05). In addition, rapamycin inhibited the mTOR signal pathway factors during leucine treatment. In sum, the leucine regulates α-amylase and trypsin synthesis in dairy calves through the regulation of the mTOR signal pathways.
The development of advanced fuel fabrication technologies is important for developing accident-tolerant fuels and engineering fuels for safer and more effective nuclear energy systems. In this work, commercial-size uranium dioxide (UO2) fuel pellets with a theoretical density of 95% were consolidated by spark plasma sintering (SPS) at 1600°C for 5 min. Systematic investigations suggest uniform densification and stoichiometric UO2 with an ideal fluorite structure across the commercial-size fuel pellet, but with a distributed grain structure because of non-uniform distribution of temperature during sintering. This work demonstrates a great potential of using SPS for fabricating nuclear fuels at a cost-effective manner.
The experiments reported in this research communication aimed to plot the expression pattern of Sirt3, a master regulator of energy metabolism and antioxidation defence, in the liver of dairy goats during perinatal period. Ten healthy dairy goats in late pregnancy were chosen, and needle biopsy was applied to collect liver samples at 1-week intervals. Protein levels of hepatic Sirt3 were analysed by western-blotting. Serum enzyme activities of manganese superoxide dismutase (Mn-SOD) and non-esterified fatty acids (NEFA) levels were measured, and their correlation with Sirt3 mRNA levels was also estimated. Compared with >3-week before parturition (BP), Sirt3 proteins were significantly reduced at 1-week after parturition (AP) and 2-week AP (P < 0·05), but increased on the day of parturition (P < 0·01). Correlation analysis revealed a positive association between hepatic Sirt3 mRNA levels and serum enzyme activity of Mn-SOD (r = 0·46), but a negative association between that and serum NEFA levels (r = −0·41). These data indicate that the decreased hepatic expression of Sirt3 might be one of the reasons that dairy goats undergo oxidative stress after parturition.
Facilitated by recent establishment of terrestrial networks and satellite constellations of Automatic Identification System (AIS) receivers, ship trajectories are becoming increasingly available and the size of recorded trajectories is getting larger. Large sets of trajectories create problems of storing, transmitting and processing data. Using appropriate methods, an accurate representation of the original trajectories can be obtained by compressing redundant information, while maintaining the main characteristic elements. In this paper, a new scheme and the implementation of the Douglas-Peucker (DP) algorithm are presented, which can simplify AIS trajectories by extracting characteristic points. As for the simplification threshold, the solo parameter of the DP algorithm, a new AIS-based minimum ship domain evaluation method is proposed and acts as criteria for simplification threshold determination. Finally, a validation is made to examine the effectiveness of the DP simplification algorithm and the rationality of the simplification threshold. The result indicates that the DP algorithm can simplify AIS trajectories effectively; the simplification threshold is scientific and reasonable.
This work developed a phase congruency algorithm combined with texture analysis to quantitatively characterize collagen morphology in second-harmonic generation (SHG) images from human scars. The extracted phase and texture parameters of the SHG images quantified collagen directionality, homogeneity, and coarseness in scars and varied with scar duration. Phase parameters showed an increasing tendency of the mean of phase congruency with scar duration, indicating that collagen fibers are better oriented over time. Texture parameters calculated from local difference local binary pattern (LD-LBP) and Haar wavelet transform, demonstrated that the LD-LBP variance decreased and the energy of all subimages increased with scar duration. It implied that collagen has a more regular pattern and becomes coarser with scar duration. In addition, the random forest regression was used to predict scar duration, demonstrating reliable performance of the extracted phase and texture parameters in characterizing collagen morphology in scar SHG images. Results indicate that the extracted parameters using the proposed method can be used as quantitative indicators to monitor scar progression with time and can help understand the mechanism of scar progression.
Spherical robot is a special kind of nonholonomic system that cannot be converted to chained form, which means most of the well-known control methodologies are not suitable for this system. For the trajectory tracking of BHQ-1, a spherical robot designed by our lab, a two-state trajectory tracking controller is proposed in this paper. First, the kinematic model of the robot is built using screw theory and exponential method and the controllability is proved based on the differential geometric control theory. Then to solve the two-state trajectory tracking problem of BHQ-1, a shunting model of neurodynamics and Lyapunov's direct method are combined to design a two-state trajectory tracking controller, of which the Lyapunov stability is validated. Finally, typical simulation examples, such as tracking linear, circular, and sinusoidal trajectories, are introduced to verify the effectiveness of the proposed controller. In this paper the proposed method can also be applied to the control of other spherical robots.
Marine traffic survey is a fundamental part of marine traffic engineering. In the assessment of the safety or effectiveness in particular water areas, the distribution of ship tracks is always included as one of the most significant results of a marine traffic survey. In this paper, methods of marine traffic survey are discussed and an appropriate method is selected to obtain the traffic data considering the available research circumstances in China. A semi-automatic artificial way of plotting a distribution diagram of ship tracks is presented with illustrations. Details of the diagram plotted by using the collected traffic data are described for reference.
Successful production of cloned animals derived from somatic cells has been achieved in sheep, cattle, goats, mice, pigs, rabbits, etc. But the efficiency of nuclear transfer is very low in all species. The present study was conducted to examine somatic nucleus remodelling and developmental ability in vitro of rabbit embryos by transferring somatic cells into enucleated germinal vesicle (GV), metaphase I (MI) or metaphase II (MII) oocytes. Microtubules were organized around condensed chromosomes after the nucleus had been transferred into any of the three types of cytoplasm. A bipolar spindle was formed in enucleated MII cytoplasm. Most of the nuclei failed to form a normal spindle within GV and MI cytoplasm. Some chromosomes scattered throughout the cytoplasm and some formed a monopolar spindle. Pseudopronucleus formation was observed in all three types of cytoplasm. Reconstructed embryos with MI and MII cytoplasm could develop to blastcysts. Nuclei in GV cytoplasm could develop only to the 4-cell stage. These results suggest that (1) GV material is important for nucleus remodelling after nuclear transfer, and (2) oocyte cytoplasm has the capacity to dedifferentiate somatic cells during oocyte maturation.
Nano-AgI arrays were synthesized by electrochemical double liquor deposition in ordered porous alumina membrane. On the basis of the analysis of x-ray diffraction patterns, the assembly of nano-AgI/Al2O3 is a mixture of a cubic zinc blende type γ–AgI and a hexagonal wurtzite type β–AgI. The visible–ultraviolet optical absorption measuring showed that the assembly only had an absorption edge at 2.82 eV and exhibited the optical features of a semiconductor with a direct band gap. The absorption edge of the assembly was shifted to a shorter wavelength compared with pure γ–AgI and a longer wavelength compared with pure β–AgI. We believed that the change of the absorption edge of the assembly is due to the mixture of γ–AgI and β–AgI.
We prepared Ce3+-doped silica by the sol-gel method and studied the effect of annealing on fluorescence of these samples. Different fluorescence was observed for samples annealed at different temperatures, changing gradually from solution like fluorescence to fluorescence similar to that observed in the Ce3+-doped silica prepared by chemical vapor deposition. It was found that the emission intensity first decreased with increasing annealing temperature until 500 °C, and then increased with the temperature ranging from 500 to 950 °C. Meanwhile, the emission peak showed a large red shift and an obvious broadening. These changes were attributed to the annealing-induced structural evolution in silica: Ce3+ ions changed from coordinating with water and terminal OH-groups to embedding in silica network.
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