Effect of Relief-hole Diameter on Die Elastic Deformation during Cold Precision Forging of Helical Gears

During cold precision forging of helical gears, the die experiences high forming pressure resulting in elastic deformation of the die, a main factor affecting dimensional accuracy of a formed gear. The divided flow method in material plastic deformation is an effective way to reduce the forming force and the die pressure during cold precision forging of helical gears. In this study, by utilizing the flow-relief-hole method, a billet design with different initial diameters of the relief-hole is developed to improve the dimensional accuracy of cold forging gears. Three-dimensional Finite Element (FE) models are established to simulate the plastic deformation process of billet during cold precision forging of a helical gear and to determine the forming force acting on the die. Further models of die stress analysis are developed to examine the die elastic deformation and distribution of the displacement. Effects of the relief-hole diameters on die elastic deformation are studied. The results show that the elastic deformation of the die is different in the addendum, dedendum, and involute parts of forging gear using different relief-hole diameters. The die elastic deformation increases firstly and then decreases when the relief-hole diameter increases. The tooth portions are of larger elastic deformation and the peak value locates in the addendum. It shows the importance of optimizing the relief-hole diameter to minimize the dimensional inaccuracy of forging gears caused by the die elastic deformation

catena-Poly[[(1,10-phenanthroline-κ2 N,N′)cadmium(II)]-μ-oxalato-κ4 O 1,O 2:O 1′,O 2′]

In the title complex, [Cd(C2O4)(C12H8N2)]n, the CdII atom has a distorted octa­hedral coordination, defined by four O atoms from two symmetry-related oxalate ligands and by two N atoms from a bidentate 1,10-phenanthroline ligand. Each oxalate ligand bridges two CdII atoms, generating a zigzag chain structure propagating along [100]. The packing of the structure is consolidated by non-classical C—H⋯O hydrogen-bonding inter­actions

Role of adiponectin/phosphatidylinositol 3-kinase/protein kinase B signaling pathway on limb ischemic preconditioning on myocardial protection

The adiponectin/phosphatidylinositol 3-kinase/protein kinase B (ADP/PI3k/Akt) signal transduction  pathway has an important role in promoting cell survival. This study was designed to determine if the  ADP/PI3K/Akt signaling pathway has a role in the mechanism of ischemia–reperfusion injury in vivo.  Sprague–Dawley rats were divided into five groups of six: Group A was the sham group, group B was the  myocardial ischemia–reperfusion injury (MIRI) group; the left anterior descending coronary artery (LAD)  was ligated and, after 30 min of ischemia, reperfusion was conducted for 120 min, group C was the limb  ischemia preconditioning (LIPC) group; the femoral artery was blocked continuously for 5 min, and  sustainable reperfusion was carried out for 5 min, and this procedure was repeated thrice. The MIRI experiment was carried out on the fourth day after consecutive preconditioning for 3 days. The surgical  procedure was the same as with the MIRI model. Group D was the LY294002 pretreatment group: 15 min before reperfusion, ischemic rats underwent pretreatment with LY294002. The final group was the  LIPC+LY294002 group; after limb ischemia preconditioning, rats underwent LY294002 pretreatment 15  min before reperfusion. Expression of ADP and adiponectin receptor 1 (ADPR1) messenger ribonucleic acid (mRNA), PI3k and p-Akt protein increased significantly in the myocardial tissue of the LIPC group in  comparison with that in the sham group. This finding suggests that limb ischemic preconditioning  increased the expression of ADP in the myocardial tissue of rats with myocardial ischemia–reperfusion  injury. It also demonstrated that ADP activated PI3k by the ADP/PI3k/Akt signaling pathway to increase the phosphorylation of the effector protein Akt.Key words: Limb ischemic preconditioning, ischemia–reperfusion injury, phosphatidylinositol 3-kinase  (PI3k), protein kinase (p-Akt), signal transduction

Use of low-dose computed tomography to assess pulmonary tuberculosis among healthcare workers in a tuberculosis hospital

BACKGROUND: According to the World Health Organization, China is one of 22 countries with serious tuberculosis (TB) infections and one of the 27 countries with serious multidrug-resistant TB strains. Despite the decline of tuberculosis in the overall population, healthcare workers (HCWs) are still at a high risk of infection. Compared with high-income countries, the TB prevalence among HCWs is higher in low- and middle-income countries. Low-dose computed tomography (LDCT) is becoming more popular due to its superior sensitivity and lower radiation dose. However, there have been no reports about active pulmonary tuberculosis (PTB) among HCWs as assessed with LDCT. The purposes of this study were to examine PTB statuses in HCWs in hospitals specializing in TB treatment and explore the significance of the application of LDCT to these workers. METHODS: This study retrospectively analysed the physical examination data of healthcare workers in the Beijing Chest Hospital from September 2012 to December 2015. Low-dose lung CT examinations were performed in all cases. The comparisons between active and inactive PTB according to the CT findings were made using the Pearson chi-square test or the Fisher’s exact test. Comparisons between the incidences of active PTB in high-risk areas and non-high-risk areas were performed using the Pearson chi-square test. Analyses of active PTB were performed according to different ages, numbers of years on the job, and the risks of the working areas. Active PTB as diagnosed by the LDCT examinations alone was compared with the final comprehensive diagnoses, and the sensitivity and positive predictive value were calculated. RESULTS: A total of 1 012 participants were included in this study. During the 4-year period of medical examinations, active PTB was found in 19 cases, and inactive PTB was found in 109 cases. The prevalence of active PTB in the participants was 1.24%, 0.67%, 0.81%, and 0.53% for years 2012 to 2015. The corresponding incidences of active PTB among the tuberculosis hospital participants were 0.86%, 0.41%, 0.54%, and 0.26%. Most HCWs with active TB (78.9%, 15/19) worked in the high-risk areas of the hospital. There was a significant difference in the incidences of active PTB between the HCWs who worked in the high-risk and non-high-risk areas (odds ratio [OR], 14.415; 95% confidence interval (CI): 4.733 – 43.896). Comparisons of the CT signs between the active and inactive groups via chi-square tests revealed that the tree-in-bud, cavity, fibrous shadow, and calcification signs exhibited significant differences (P = 0.000, 0.021, 0.001, and 0.024, respectively). Tree-in-bud and cavity opacities suggest active pulmonary tuberculosis, whereas fibrous shadow and calcification opacities are the main features of inactive pulmonary tuberculosis. Comparison with the final comprehensive diagnoses revealed that the sensitivity and positive predictive value of the diagnoses of active PTB based on LDCT alone were 100% and 86.4%, respectively. CONCLUSIONS: Healthcare workers in tuberculosis hospitals are a high-risk group for active PTB. Yearly LDCT examinations of such high-risk groups are feasible and necessary. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s40249-017-0274-6) contains supplementary material, which is available to authorized users

Movable Fiber-Integrated Hybrid Plasmonic Waveguide on Metal Film

A waveguide structure consisting of a tapered nanofiber on a metal film is proposed and analyzed to support highly localized hybrid plasmonic modes. The hybrid plasmonic mode can be efficiently excited through the in-line tapered fiber based on adiabatic conversion and collected by the same fiber, which is very convenient in the experiment. Due to the ultrasmall mode area of plasmonic mode, the local electromagnetic field is greatly enhanced in this movable waveguide, which is potential for enhanced coherence light emitter interactions, such as waveguide quantum electrodynamics, single emitter spectrum and nonlinear optics

Adaptations to climate-mediated selective pressures in sheep

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