Effect of convex surface splicing characteristics of mold on the machining error in milling process

Dongkai Jia,Shi Wu,Chunfeng Wang,Xian-li Liu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.1

Most of the molds of automobile panels are spliced with insert-type modules. Sudden variations in load and impact vibration can occur while processing splicing area, which affects the overall quality of this area. In this study, to improve the machining accuracy of the convex-surface splicing area, the influence of thermal deformation of tool, residual height, and impact vibrations on the machining error of this area is firstly analyzed. Subsequently, based on the motion path of the cutting edge of ball-end mill, a comprehensive error model for mill machine is established, which accounts for the tool error, residual height, and milling vibration. Finally, based on the milling experiment of convex-surface splicing die, the variation trend of machining error with machining inclination, spindle speed, and cutting depth is examined to verify comprehensive error algorithm MATLAB simulation results. The experimental results show that the prediction error of the proposed error model is between 4-8 % when the machining inclination is positive, and it is between 18-21 % when the machining inclination is negative, indicating that the proposed model is consistent with the experimental data. Novelty aspects, the present work: (i) proposes a mechanistic modeling approach to predicting machining error considering of thermal deformation, residual height, and impact vibrations for splicing mold; (ii) demonstrates that thermal deformation, residual height, and impact vibrations need to be taken into account for modeling the comprehensive machining error of splicing mold; (iii) contributes to practical industrial application of finishing machining technology of mold and die with splicing characteristics.

CT-Based Leiden Score Outperforms Confirm Score in Predicting Major Adverse Cardiovascular Events for Diabetic Patients with Suspected Coronary Artery Disease

Liu Zinuan,Ding Yipu,Dou Guanhua,Wang Xi,Shan Dongkai,He Bai,Jing Jing,Chen Yundai,Yang Junjie 대한영상의학회 2022 Korean Journal of Radiology Vol.23 No.10

Objective: Evidence supports the efficacy of coronary computed tomography angiography (CCTA)-based risk scores in cardiovascular risk stratification of patients with suspected coronary artery disease (CAD). We aimed to compare two CCTAbased risk score algorithms, Leiden and Confirm scores, in patients with diabetes mellitus (DM) and suspected CAD. Materials and Methods: This single-center prospective cohort study consecutively included 1241 DM patients (54.1% male, 60.2 ± 10.4 years) referred for CCTA for suspected CAD in 2015–2017. Leiden and Confirm scores were calculated and stratified as < 5 (reference), 5–20, and > 20 for Leiden and < 14.3 (reference), 14.3–19.5, and > 19.5 for Confirm. Major adverse cardiovascular events (MACE) were defined as the composite outcomes of cardiovascular death, nonfatal myocardial infarction (MI), stroke, and unstable angina requiring hospitalization. The Cox model and Kaplan–Meier method were used to evaluate the effect size of the risk scores on MACE. The area under the curve (AUC) at the median follow-up time was also compared between score algorithms. Results: During a median follow-up of 31 months (interquartile range, 27.6–37.3 months), 131 of MACE were recorded, including 17 cardiovascular deaths, 28 nonfatal MIs, 64 unstable anginas requiring hospitalization, and 22 strokes. An incremental incidence of MACE was observed in both Leiden and Confirm scores, with an increase in the scores (log-rank p < 0.001). In the multivariable analysis, compared with Leiden score < 5, the hazard ratios for Leiden scores of 5–20 and > 20 were 2.37 (95% confidence interval [CI]: 1.53–3.69; p < 0.001) and 4.39 (95% CI: 2.40–8.01; p < 0.001), respectively, while the Confirm score did not demonstrate a statistically significant association with the risk of MACE. The Leiden score showed a greater AUC of 0.840 compared to 0.777 for the Confirm score (p < 0.001). Conclusion: CCTA-based risk score algorithms could be used as reliable cardiovascular risk predictors in patients with DM and suspected CAD, among which the Leiden score outperformed the Confirm score in predicting MACE.

Role of silibinin in the management of diabetes mellitus and its complications

Chun Chu,Da-Hong Li,Shicheng Zhang,Takashi Ikejima,Ying Jia,Dongkai Wang,Fanxing Xu 대한약학회 2018 Archives of Pharmacal Research Vol.41 No.8

Diabetes mellitus is globally approaching epidemicproportions and acts as a major cause of a number ofserious health problems diagnosed as diabetic complications. The current oral drugs in the treatment of diabetesand its complications could meet some but not all of thepatients’ needs, and the development of novel drugs with ahypoglycemic effect is urgently required. Silibinin, aflavonolignan traditionally used for the treatment of gallbladderand hepatic diseases, was reported to improveglycemic homeostasis by improving the activity of pancreaticb-cells, increasing insulin sensitivity of liver andmuscle cells, and decreasing lipid deposition in adipocytes. Researches also indicated the effectiveness of silibinin incontrolling several diabetic complications including neuropathy,retinopathy, impaired healing, hepatopathy, cardiomyopathy,nephropathy, and osteoporosis. In thisreview, we summarize the recent anti-diabetes findings ofsilibinin and clarify the underlying pharmacologicalmechanisms, and update the knowledge in understandingthe role of silibinin in control of diabetic complications.

Involvement of Estrogen Receptor-α in the Activation of Nrf2-Antioxidative Signaling Pathways by Silibinin in Pancreatic β-Cells

( Chun Chu ),( Xiang Gao ),( Xiang Li ),( Xiaoying Zhang ),( Ruixin Ma ),( Ying Jia ),( Dahong Li ),( Dongkai Wang ),( Fanxing Xu ) 한국응용약물학회 2020 Biomolecules & Therapeutics(구 응용약물학회지) Vol.28 No.2

Silibinin exhibits antidiabetic potential by preserving the mass and function of pancreatic β-cells through up-regulation of estrogen receptor-α (ERα) expression. However, the underlying protective mechanism of silibinin in pancreatic β-cells is still unclear. In the current study, we sought to determine whether ERα acts as the target of silibinin for the modulation of antioxidative response in pancreatic β-cells under high glucose and high fat conditions. Our in vivo study revealed that a 4-week oral administration of silibinin (100 mg/kg/day) decreased fasting blood glucose with a concurrent increase in levels of serum insulin in high-fat diet/streptozotocin- induced type 2 diabetic rats. Moreover, expression of ERα, NF-E2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) in pancreatic β-cells in pancreatic islets was increased by silibinin treatment. Accordingly, silibinin (10 μM) elevated viability, insulin biosynthesis, and insulin secretion of high glucose/palmitate-treated INS-1 cells accompanied by increased expression of ERα, Nrf2, and HO-1 as well as decreased reactive oxygen species production in vitro. Treatment using an ERα antagonist (MPP) in INS-1 cells or silencing ERα expression in INS-1 and NIT-1 cells with siRNA abolished the protective effects of silibinin. Our study suggests that silibinin activates the Nrf2-antioxidative pathways in pancreatic β-cells through regulation of ERα expression.

The Removal of Benzene and Toluene in Natural Gas with Cryogenic Liquid Propane: Effects and a Cyclic Purification Process

Dong Kai,Rong Qianqian,Xiao Ruirui,Gao Yunfei,Wang Fuchen 한국화학공학회 2024 Korean Journal of Chemical Engineering Vol.41 No.4

Liquefi ed natural gas production plants usually suff er from line blockage, which causes economic, environmental, and safety issues. The blockage, mainly caused by the solidifi cation of heavy hydrocarbons, should be avoided or mitigated by removing the impurities as thoroughly as possible. In this work, we proposed a scheme taking cryogenic liquefi ed propane as absorbent to absorb heavy hydrocarbons in the liquefi ed natural gas production process. This paper fi rst investigated freeze-out profi les of liquefi ed natural gas combined with marginal benzene and toluene by the ThermoFAST simulator, which showed that the precipitated solid tended to form under a low temperature, which posed challenges in purifi cation. Subsequently, the feasibility of using liquefi ed propane as an absorbent to remove benzene and toluene was studied using Aspen Plus. A cryogenic absorption and regeneration process for liquefi ed natural gas purifi cation was proposed, and factors infl uencing the performance were investigated. The results showed that the hydrocarbon impurities are removed more thoroughly at a high fl owrate of the recycled absorbent stream. The absorption process exhibited an apparent cooling eff ect mainly caused by the vaporization of liquefi ed propane to the gas phase, and the higher operation temperature impedes the vaporization process. For a better purifi cation eff ect, the system should be operated under a lower pressure or with a higher recycled absorption solution fl owrate. Based on the design simulation results, utilizing liquefi ed propane as an absorbent to remove heavy hydrocarbons is novel and promising for LNG purifi cation.