Influence of pass spacing on the spinning process of nickel-based alloy conical casing

High temperature nickel-based alloys are prone to forming defects due to serious work hardening, and the pass spacing is an important parameter in multi-pass drawing and spinning. Using GH4169 superalloy as the material, a Finite Element Model (FEM) was established based on the Simufact platform, and the influence of the pass spacing on the spinning process was explored by using the concave curve and circular arc trajectory. The results show that the stress-strain increases with the increase of the pass spacing. Obtain the optimal pass spacing under specific conditions: blank wall thickness t = 2,5 mm, blank diameter d = 250 mm, feed ratio f = 1,2 mm/rad, mandrel speed n = 300 r/min, pass spacing p = 14 mm

Influence of pass spacing on the spinning process of nickel-based alloy conical casing

High temperature nickel-based alloys are prone to forming defects due to serious work hardening, and the pass spacing is an important parameter in multi-pass drawing and spinning. Using GH4169 superalloy as the material, a Finite Element Model (FEM) was established based on the Simufact platform, and the influence of the pass spacing on the spinning process was explored by using the concave curve and circular arc trajectory. The results show that the stress-strain increases with the increase of the pass spacing. Obtain the optimal pass spacing under specific conditions: blank wall thickness t = 2,5 mm, blank diameter d = 250 mm, feed ratio f = 1,2 mm/rad, mandrel speed n = 300 r/min, pass spacing p = 14 mm

The effects of dog management on Echinococcus spp. prevalence in villages on the eastern Tibetan Plateau, China

Background The pastoral area of the eastern Tibetan plateau is a very important human echinococcosis endemic region. Domestic dogs are the main definitive host for the transmission of Echinococcus granulosus sensu lato (s.1.) and E. multilocularis to humans. To control the infection risks, a national-level canine echinococcosis prevention and control program has been implemented since 2015 in Shiqu County, Sichuan, China, The objective of this investigation was to evaluate its effect on Echinococcus spp. prevalence in dogs. Methods We surveyed 69 households with 84 owned dogs, for dog keeping information in the villages of Rizha and Eduoma. A total of 105 dog fecal samples, consisting of 75 from owned dogs and 30 unknown dog fecal samples were collected between 2015 and 2017 to determine Echinococcus spp. prevalence using copro-PCR. Eight variables based on household surveys were included into a logistic regression model for significantly relevant factors to canine echinococcosis prevalence in dogs. Results The overall Echinococcus spp. copro-DNA prevalence decreased significantly in dogs from 51.2% (2015) to 20.0% (2017) in Rizha, and insignificantly from 11.5% (2016) to 4.3% (2017) in Eduoma. Echinococcus multilocularis was the most prevalent species continually detected during the entire research period, while E. granulosus was rare and not detected in 2017. Echinococcus shiquicus prevalence was as high as E. multilocularis , although only detected in 2015 in Rizha. Unleashed dog feces were mainly collected in Rizha Village in 2015. Although 93.2% of owned dogs were leashed, and the monthly praziquantel dosing rate reached 97%, E. multilocularis infection could still be detected in 11.1% of owned dogs in 2017. Monthly deworming, leashing dogs 24h per day, and the avoidance of dogs feeding on livestock viscera are significant measures to prevent canine echinococcosis infection in owned dogs. Conclusion Carrying out a canine echinococcosis prevention and control program can significantly decrease the Echinococcus prevalence. The potential contact between leashed dogs and wild small mammals is still a risk to re-infect owned dogs. This study shows that the long term application of regular dog dosing in the vast remote echinococcosis endemic areas of west China is still challenging

Effect of process parameters on microstructure of 42CrMo steel ball hot skew rolling

Microstructure grain refinement is an effective way to improve the quality of 42CrMo steel ball. A three-dimensional thermal-mechanical-microstructure coupled Finite element model (FEM) of steel ball skew rolling is established in the finite element simulation software. Simufact software was used to simulate the effects of process parameters on the microstructure of steel balls, and the effects of roll Angle, roll temperature and roll speed on the average grain size of rolled pieces were analyzed by single factor variable method. The research results provide some reference for the improvement of 42CrMo steel ball quality

Ectopic expression of a vesicle trafficking gene, OsRab7, from Oryza sativa, confers tolerance to several abiotic stresses in Escherichia coli

Rab7 is a small GTP-binding protein involved in intracellular vesicle trafficking from late endosome to the vacuole. In this study, the gene OsRab7 was isolated from Oryza sativa. Over-expression of OsRab7 gene in Escherichia coli increased the resistance to heat, cold and salt stress. In addition, subcellular localization of OsRab7 protein in E. coli and onion cells all revealed that OsRab7 protein is specifically present in the cytoplasm. These results showed that OsRab7 plays an important role in stress tolerance and probably develop abiotic stress tolerance in E. coli and planta with similar mechanism.Key words: Vesicle trafficking, rice, OsRab7, Escherichia coli, abiotic stresses

Molecular Dynamics Study of Bamboo-like Carbon Nanotube Nucleation

MD simulations based on an empirical potential energy surface were used to study the nucleation of bamboo-like carbon nanotubes (BCNTs). The simulations reveal that inner walls of the bamboo structure start to nucleate at the junction between the outer nanotube wall and the catalyst particle. In agreement with experimental results, the simulations show that BCNTs nucleate at higher dissolved carbon concentrations (i.e., feedstock pressures) than those where non-bamboolike carbon nanotubes are nucleated