Standardizing catch per unit effort by machine learning techniques in longline fisheries: a case study of bigeye tuna in the Atlantic Ocean

Support vector machine (SVM) is shown to have better performance in catch per unit of effort (CPUE) standardization than other methods. The SVM performance highly relates to its parameters selection and has not been discussed in CPUE standardization. Analyzing the influence of parameter selection on SVM performance for CPUE standardization could improve model construction and performance, and thus provide useful information to stock assessment and management. We applied SVM to standardize longline catch per unit fishing effort of fishery data for bigeye tuna (Thunnus obesus) in the tropical fishing area of Atlantic Ocean and evaluated three parameters optimization methods: a Grid Search method, and two improved hybrid algorithms, namely SVMs in combination with the particle swarm optimization (PSO-SVM), and genetic algorithms (GA-SVM), in order to increase the strength of SVM. The mean absolute error (MAE), mean square error (MSE), three types of correlation coefficients and the normalized mean square error (NMSE) were computed to compare the algorithm performances. The PSO-SVM and GA-SVM algorithms had particularly high performances of indicative values in the training data and dataset, and the performances of PSO-SVM were marginally better than GA-SVM. The Grid search algorithm had best performances of indicative values in testing data. In general, PSO was appropriate to optimize the SVM parameters in CPUE standardization. The standardized CPUE was unstable and low from 2007 to 2011, increased during 2011- 2013, then decreased from 2015 to 2017. The abundance index was lower compared with before 2000 and showed a decreasing trend in recent years

Microstructure and Mechanical Property of Aluminum Alloy Plate AA 7055

Through-thickness microstructure and mechanical property of AA 7055-T7751 aluminum alloy plate were investigated by using electron backscattered diffraction (EBSD), transmission electron microscope (TEM) and small angle X-ray scattering(SAXS). The results indicate an inhomogeneous distribution of microstructure through the thickness. The degree of recrystallization decreases gradually from 69% to 19.1%, as deepening from the surface to the center of the plate. The size of subgrains decreases from 10 μm at the surface to around 2 μm at the center. Strong texture of rolling type is observed near the center but the intensity decreases gradually as nearing the surface and the shear texture becomes the dominant. High density of plate-like η' phases are observed in the alloy, indicating the sufficient precipitation. η' precipitates of this condition are around 3.7 nm in radius, 1-3 nm in thickness and are found coherent with the Al matrix with a coherent strain of 0.0133, showing a strong strengthening effect. The heterogeneity in grain scale does not influence the distribution and the morphology of precipitates. The yield strength (L direction) varies linearly along the thickness direction of the plate, fitting an equation of σy=-38.7S+604.8 (0≤S≤1). The variation of yield strength is related to the heterogeneity of grain structure

Properties of graphene oxide modified epoxy resin and its composites

Graphene oxide (GO) modified epoxy resin (GH81) was prepared by mechanical grinding, and the dispersion of GO in the epoxy resin (H81) was analyzed by optical microscope, while the melting performances and curing behaviors of H81 and GH81 were researched through rheometer and differential scanning calorimeter respectively. The results show that GO is uniformly dispersed into the matrix resin，and the addition of GO hardly affects the melt viscosity and curing condition of the matrix resin at all. In addition, the 0° tensile strength, bending strength and compression strength of GH81 based carbon fiber reinforced composite (GH81-300) are 2270 MPa, 2239 MPa and 1529 MPa respectively, which is increased by 6.4%, 7.2% and 7.1% respectively, as compared with that of composite without GO

Research progress of alloy materials' application in lithium metal anode

Lithiumis are considered as an ideal anode material for the next generation high energy density secondary batteries owing to its extremely low reduction potential and high specific capacity. However, its commercial application in lithium metal batteries is hindered by the problems of lithium dendritic growth, volume expansion effect and interface instability. To solve this problems, effective strategies including alloy anode, interface protection, structured anode design and solid electrolyte have been developed. Alloy materials play an important role in above strategies with its superior specific capacity, high Li+ conductivity and good lithium affinity. The electrochemical properties of alloy were reviewed and the recent research development of alloy materials' application in lithium metal anode was futher discussed. Last, the main existing problems of alloy materials' application in lithium metal anode were summarized and it was pointed out that the basic theoretical research should be strengthened

Regulation and Molecular Mechanism of TLR5 on Resistance to Escherichia coli F18 in Weaned Piglets

Toll-like receptor 5 (TLR5) plays an important role in immune system. In this study, we performed transcriptome analysis of the duodenum in E. coli F18-resistant and -sensitive Sutai weaned piglets and analyzed the differential expression of TLR5. The cellular localization of TLR5 was investigated, and the effect of TLR5 expression on E. coli invasion was evaluated after pig small intestinal epithelial cell lines (IPEC-J2) were stimulated by E. coli. The results showed that TLR5 expression level in duodenum and jejunum were significantly higher in E. coli F18-sensitive than in E. coli F18-resistant piglets. TLR5 protein was mainly expressed in the cytoplasm and cell membrane. The expression of genes associated with the TLR5 signaling pathway were significantly higher in TLR5-overexpressed cells than in control cells. Bacterial adhesion was higher in TLR5-overexpressed cells than in blank cells and lower in TLR5 interference than in blank cells. The core promoter region of TLR5 included two CpG islands and 16 acting elements. The methylation of the mC-6 site in the second CpG island of the promoter region had a regulatory effect on TLR5 expression. Therefore, TLR5 plays an important regulatory role on E. coli invasion. Low expression of TLR5 inhibited the immune response and decreased cell damage, which was conducive to the resistance to E. coli stimulation. In conclusion, this study preliminarily revealed the molecular mechanism of TLR5 gene regulating the resistance of piglets to Escherichia coli, and provided a new candidate gene for screening Escherichia coli resistance markers in pigs

Effects of porcine MyD88 knockdown on the expression of TLR4 pathway-related genes and proinflammatory cytokines

Synopsis As a critical adapter protein in Toll-like receptor (TLR)/Interleukin (IL)-1R signalling pathway, myeloid differentiation protein 88 (MyD88) plays an important role in immune responses and host defence against pathogens. The present study was designed to provide a foundation and an important reagent for the mechanistic study of MyD88 and its role TLR/IL-1R signalling pathways in porcine immunity. Lentivirus-mediated RNAi was used to generate a porcine PK15 cell line with a silenced MyD88 gene and quantitative real-time PCR (qPCR) and Western blotting were used to detect changes in the expression of critical genes in the Toll-like receptor 4 (TLR4) signalling pathway. ELISA was used to measure the levels of seven proinflammatory cytokines -interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α), IL-6, IL-8, IL-12, macrophage inflammatory protein (MIP)-1α and MIP-1β -in cell culture supernatants after MyD88 silencing. We successfully obtained a PK15 cell line with 61% MyD88 mRNA transcript down-regulated. In PK15 cells with MyD88 silencing, the transcript levels of TLR4 and IL-1β were significantly reduced, whereas there were no significant changes in the expression levels of cluster of differentiation antigen 14 (CD14), interferon-α (IFN-α) or TNF-α. The ELISA results showed that the levels of most cytokines were not significantly changed apart from IL-8 without stimulation, which was significantly up-regulated. When cells were induced by lipopolysaccharide (LPS) (0.1 μg/ml) for 6 h, the global level of seven proinflammatory cytokines up-regulated and the level of IL-1β, TNF-α, IL-6, IL-8 and IL-12 of Blank and negative control (NC) group up-regulated more significantly than RNAi group (P < 0.05), which revealed that the MyD88 silencing could reduce the TLR4 signal transduction which inhibited the release of proinflammatory cytokines and finally leaded to immunosuppression

Effect of the Pre-Shot Peening and Nitrogen Ion Implantation Combined Surface Treatments on the Surface Structure and Properties of Gear Steel 16Cr3NiWMoVNbE

Transmission engineering components need to fulfill requirements for adequate wear resistance and fatigue resistance, which are related to their surface properties. In this paper, we combined shot peening and nitrogen ion implantation to improve the surface properties of 16Cr3NiWMoVNbE gear steel. The average surface roughness decreased slightly after the ion implantation because of the high-speed impact of implanted ions having the surface etching role. The maximum compressive residual stress of the near-surface layer after the surface treatment increased by more than 11.8–15.9% compared with shot peening. The nitrogen ions diffused through the peening deformation channel, and the deformation degree and the implantation temperature were positively correlated with the diffusion process. The surface nano-hardness obtained by ion implantation after shot peening was increased by 124.4% compared to the AR state

Properties of ABS/Organic-Attapulgite Nanocomposites Parts Fabricated by Fused Deposition Modeling

The paper discusses the mechanical and thermal performance manifested in natural nanorods attapulgite (ATP) reinforced Acrylonitrile butadiene styrene (ABS) nanocomposites in the process of fused deposition modeling (FDM). Molten extrusion technique was taken to manufacture the filaments of ABS/ organic-attapulgite ( OAT) nanocomposites with different mass fraction and the printing operation was made by one commercial FDM three-dimensional (3D) printer. Results indicate that the mechanical performance of these FDM 3D printed specimens are improved obviously via the introduction of OAT, and tensile strength of the ABS/OAT nanocomposites parts with only 2 wt% OAT addition is enhanced by 48.1%. At the same time, the addition OAT can reduce the linear expansion coefficient and creep flexibility, and improve the thermal stability and dimensional accuracy of these FDM 3D printed parts

New Insight into the Molecular Mechanism of the <i>FUT2</i> Regulating <i>Escherichia coli</i> F18 Resistance in Weaned Piglets

Escherichia coli (E. coli) F18 is the main pathogen responsible for post-weaning diarrhea (PWD) in piglets. Resistance to E. coli F18 depends on the expression of the cognate receptors in the intestinal epithelial cells. However, the molecular mechanism of E. coli F18 resistance in weaned piglets remains unclear. Here, we performed a comparative transcriptome study of the duodenal tissue from Sutai E. coli F18 sensitive and resistant pigs by RNA-seq, and pig &#945;(1,2) fucosyltransferase 2 (FUT2) was identified as a host differentially expressed gene controlling the E. coli F18 infection. Function analysis showed that the FUT2 expression was high in the duodenum and jejunum, with higher levels detected in sensitive individuals than in resistant individuals (p &lt; 0.01). Expression levels of FUT2 were upregulated in IPEC-J2 cells after lipopolysaccharide (LPS)-induction or E. coli stimulation. FUT2 knockdown decreased the adhesion of E. coli F18 to IPEC-J2 cells (p &lt; 0.05). FUT2 overexpression markedly increased the adhesion of E. coli F18 to IPEC-J2 cells (p &lt; 0.05 or p &lt; 0.01). Furthermore, the FUT2 mRNA levels correlated with methylation levels of the mC-22 site in the specificity protein 1 (Sp1) transcription factor (p &lt; 0.05). Electrophoretic mobility shift assays (EMSA) showed that Sp1 interacts with the wild-type FUT2 promoter DNA, but not with methylated DNA. Our data suggested that FUT2 methylation at the mC-22 site inhibits Sp1 binding to the FUT2 promoter, thereby reducing FUT2 expression and enhancing E. coli F18 resistance in weaned piglets. These observations highlight FUT2 as a promising new target for combating E. coli F18 susceptibility in weaned piglets