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Objective: To realize the full automation of shrimp deep processing. Methods: Based on analysis of physical characteristics of northern and southern American shrimps, according to the feature of the center of gravity located between the thickest part of the shrimp body and the tail of the shrimp, an automatic orientation and grading device of shrimp head and tail was designed. Taking the clip angle between directional roller shaft line and horizontal line and the speed of directional roller as testing factors, the directional components were tested. Results: When the directional roller speed was 60 r/min, and the angle between axis line and horizontal line was 15°, the falling speed of shrimp was even and stable with high directional rate, which was benefit for subsequent grading transportation. Conclusion: The device realizes the shrimp head and tail positioning and classification, which is conducive to the full automation of shrimp processing.

Students' informal science learning experiences are believed to strongly influence their attitudes toward science and their abilities in the subject. Factors associated with students' informal science learning experiences include family socioeconomic status and perceived family support. However, little is known about whether perceived family support for children's formal and informal science learning differs significantly. The present study filled this gap by exploring how students' perceived family support for formal/ informal science learning affected the link between their socioeconomic status and their experiences of informal science learning. Survey data were collected from 486 Chinese grade 4-6 primary school students. Structural equation modeling demonstrated that the students' socioeconomic status and their informal science learning experiences were significantly and positively correlated. This association was chain-mediated through two categories of perceived family support. Specifically, students' socioeconomic status affected their informal science learning experiences through the separate mediating role of family support for formal science learning and the sequential mediation of perceived family support for formal and informal science learning. These results uncover the role that family support plays in students' science education; accordingly, parents are encouraged to help their children learn science both formally and informally.

Alclad and unclad 2E12 aerospace aluminum alloy were treated by sulfuric acid anodic oxidation. The effects of alclad layer and anodizing time on the anodization behaviour and corrosion resistance of anodic oxide layer on 2E12 aluminum alloy were studied. Surface and cross-section morphology of anodic oxide films were observed by scanning electron microscopy. The electrochemical properties of anodic oxide films were analyzed by potentiodynamic polarization curve and electrochemical impedance spectroscopy. The results show that the protective anodic oxide layers are formed on alclad and unclad 2E12 aluminum alloy. The film thickness increases with anodizing time extending. The copper rich second phase particles lead to more cavity defects and even micro cracks on anodic oxide films of unclad 2E12 aluminum alloy. The anodic oxide films on alclad 2E12 aluminum alloy are thicker and have fewer cavity defects, resulting in better corrosion resistance. The films obtained after 30min and 45min anodic oxidation treatment exhibit lower corrosion current and higher impedance of the porous layer than other anodizing time.

A series of bending fretting fatigue tests of 18CrNiMo7-6 alloy steel were carried out, the bending fretting fatigue S-N curve was built up, and an analysis was made on the test results. The results show that, the S-N curve of 18CrNiMo7-6 alloy steel presents a shape of "ε" curve, which is different from the medium carbon steel, and also different from the plain bending fatigue. With the increase of the bending fatigue stress, the fretting regime transforms from partial slip regime to mixed regime and slip regime. The wear mechanisms of fretting damage zones mainly are delaminated, abrasive wear and oxidative wear. In the mixed regime, the cracks are easy to initiate and propagate, and the cracks all originate from the subsurface of contact zone. Due to the different influence levels of the contact stress and bending fatigue stress, the initiation and propagation of the bending fretting fatigue cracks can be divided into three stages. Firstly, the cracks initiate from subsurface under the control of contact stress; then propagate to a larger angle direction under the joint control of contact stress and bending fatigue stress; lastly the cracks propagate vertically to contact surface until fracture failure under the control of bending fatigue stress.

The paper proposed a control scheme of three-level active power filter based on ip-iq harmonic current detection, fuzzy PI current control and space vector pulse width modulation. It established a mathematical model of the three-level active power filter, and introduced concrete realization of control method of DC-side voltage stabilization and neutral-point potential balancing of the three-level active power filter. The simulation and experimental results show that the three-level active power filter controlled by the scheme has good effect of harmonic compensation, and can stabilize DC-side voltage and capacitance neutral-point potential well.

Abstract Background More than 70% of patients with depression who see their doctors experience insomnia. Insomnia treatment is a very important link for depression treatment. Furthermore, antidepression treatment is also important for depression insomnia. In acupuncture, LU-7 (Lie Que) and KID-6 (Zhao Hai), which are two of the eight confluence points in meridian theory, are used as main points. An embedded needle technique is used, alternately, at two groups of points to consolidate the treatment effect. These two groups of points are BL-15 (Xin Shu) with BL-23 (Shen Shu) and BL-19 (Dan Shu) with N-HN-54 (An Mian). The effectiveness of these optimized acupuncture formulas is well proven in the practice by our senior acupuncturists in Guangdong Provincial Hospital of TCM. This study has been designed to examine whether this set of optimized clinical formulas is able to increase the clinical efficacy of depression insomnia treatment. Methods/design In this randomized controlled multicenter trial, all the eligible participants are diagnosed with depression insomnia. All participants are randomly assigned to one of two groups in a ratio of 1:1 and receive either conventional acupuncture treatment or optimized acupuncture treatment. Patients are evaluated using the Pittsburgh Sleep Quality Index(PSQI)and the Hamilton rating scale(HAMD) for depression. The use of antidepression and hypnotics drugs is also considered. Results are obtained at the start of treatment, 1 and 2 months after treatment has begun, and at the end of treatment. The entire duration of the study will be approximately 36 months. Discussion A high quality of trial methodologies is utilized in the study, and the results may provide better evidence for the effectiveness of acupuncture as a treatment for depression insomnia. The optimized acupuncture formula has potential benefits in increasing the efficacy of treating depression insomnia. Trial registration The trial was registered in Chinese Clinical Trial Register (ChiCR-TRC-00000481) on 12 August 2009.

Objectives To characterize bla NDM-carrying Salmonella recovered from a pig slaughterhouse. Methods In this study, 46 environment samples were collected from a slaughterhouse in China, and screened for carbapenem-resistant Enterobacterales. WGS, antimicrobial susceptibility testing and conjugation experiments were carried out to identify the isolates' resistance phenotypes and genetic characteristics. The phylogenetic relatedness of the Salmonella isolates obtained in this study and Salmonella (ST34 and ST29) in GenBank was determined. Results Two ST34 Salmonella Typhimurium and one ST29 Salmonella Stanley, recovered from three environmental samples (6.52%), were positive for bla NDM-1 and bla NDM-5, respectively. The two ST34 S. Typhimurium strains exhibited a close relationship (10–36 SNPs) with two human-derived bla NDM-1-bearing isolates from China (Hong Kong and Guangxi Province) and two bla NDM-negative ST34 Salmonella strains from the UK. The bla NDM-1 genes were located on IncHI2/ST3 plasmids. The capture of bla NDM-1 by the IncHI2/ST3 plasmid seems to be due to homologous recombination mediated by circular structures, as the genetic arrangements of the bla NDM-1 gene contain two IS 26 elements of the same orientation. The bla NDM-5 gene was also carried by the IncHI2/ST3 plasmid, which shares highly similar structures with other bla NDM-5-bearing IncHI2/ST3 plasmids from other sources (fish, chicken, duck, human). Conclusions This is the first report of a bla NDM-5-carrying IncHI2/ST3 plasmid in Salmonella. The clonal spread of NDM-1-producing ST34 S. Typhimurium across human and animal-associated environments, and the widespread dissemination of epidemic bla NDM-5-carrying IncHI2/ST3 plasmids among Enterobacteriaceae in China indicate the potential of further dissemination of bla NDM among Salmonella , which poses a threat to public health. [ABSTRACT FROM AUTHOR]