Data Fitting and Scenario Analysis of Vaccination in the 2014 Ebola Outbreak in Liberia

Zhifu Xie 질병관리본부 2019 Osong Public Health and Research Persptectives Vol.10 No.3

Objectives: This study aimed to extend an epidemiological model (SEIHFR) to analyze epidemic trends, and evaluate intervention efficacy. Methods: SEIHFR was modified to examine disease transmission dynamics after vaccination for the Ebola outbreak. Using existing data from Liberia, sensitivity analysis of various epidemic scenarios was used to inform the model structure, estimate the basic reproduction number ℜ0 and investigate how the vaccination could effectively change the course of the epidemic. Results: If a randomized mass vaccination strategy was adopted, vaccines would be administered prophylactically or as early as possible (depending on the availability of vaccines). An effective vaccination rate threshold for Liberia was estimated as 48.74% among susceptible individuals. If a ring vaccination strategy was adopted to control the spread of the Ebola virus, vaccines would be given to reduce the transmission rate improving the tracing rate of the contact persons of an infected individual. Conclusion: The extended SEIHFR model predicted the total number of infected cases, number of deaths, number of recoveries, and duration of outbreaks among others with different levels of interventions such as vaccination rate. This model may be used to better understand the spread of Ebola and develop strategies that may achieve a disease-free state.

Substructure-based model updating using residual flexibility mixed-boundary method

Zhifu Cao,Qingguo Fei,Dong Jiang,Shaoqing Wu 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.2

Substructure method has been widely applied in dynamic analysis of complex structures due to high computational efficiency. On the basis of Residual flexibility mixed-boundary (RFMB) substructure method, a model updating approach is proposed in this paper. Four major steps of the RFMB model updating method are summarized as: 1) Substructuring: Dividing the whole structure into residual part and reduced part according to the junction surface; 2) reduction: Using the RFMB component mode synthesis approach to reduce the order of each substructures; 3) assembly: Residual structure analysis by using the reduced assemble matrix; 4) updating: Model updating by solving the optimization problem. Numerical simulation is conducted to verify the effectiveness by adopting a cantilever plate in case I. In case II, the proposed method is applied to identify the elastic parameter of interface of a bolted joint structure using experimental data. After parameter identification, the maximum error between numerical results and the experimental data decreases to 2.44 %. And three component mode synthesis model updating methods: Craig-Bampton (CB), Mixed-boundary (MB) without considering residual flexibility and RFMB model updating approach, are applied to update the same bolted joint structure for comparing the accuracy. For comparing the computational efficiency, the RFMB model updating approach is applied to the complicated aero-engine casing structure. In case III, the average time-consuming of the Whole finite element model (WFEM) is 5.15 times to the Residual finite element model (RFEM) in the single updating iteration. Results show that the proposed approach has better performance in the finite element model updating.

Impact Mechanical Properties of Fiber Reinforced Concrete Slab with Alkali-Resistant Glass Fiber of High Zirconium

Zhifu Dong,Zongcai Deng,Junsuo Yao 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.6

This paper studied the impact resistance of high zirconium alkali-resistant glass fiber reinforced full-scale concrete slabs from the perspective of dynamics by the drop hammer test, and compared with macro-polypropylene and steel fiber. The effects of fiber type and fiber volume fractions on the impact resistance of concrete slabs were investigated, the concrete slab acceleration and the support reaction force time-history curve were measured, and the dynamic test results and failure mode of specimens were comparative analysis. All fiber reinforced concrete slabs show ductility failure, as the increase in fiber volume fractions, the impact resistance of specimens was improved more significantly, and the impact resistance of slabs exhibits secondary strengthening properties and experienced elastic-plastic phase. When the volume fraction was 0.45%, the first impact resistance of macro-polypropylene fiber and glass fiber reinforced concrete slab was similar, while when the volume fraction was 0.75%, the impact resistance of macropolypropylene fiber reinforced concrete slab was better. With the same volume fraction, the second impact resistance of macropolypropylene fiber reinforced concrete slab was better than that of glass fiber. Although the impact toughness and energy dissipation performance of high zirconium alkali-resistant glass fiber reinforced concrete compared with other fiber is not outstanding, but the comprehensive analysis shows that it has advantages in the use of the corrosion environment.

Validation of the Thyrotoxicosis-associated Insomnia Model Induced by Thyroxine through Sympathetic Stimulation: Face, Construct and Predictive Perspectives

Zhifu Ai,Hongwei He,Tingting Wang,Liling Chen,Chunhua Huang,Changlian Chen,Pengfei Xu,Genhua Zhu,Ming Yang,Yonggui Song,Dan Su 한국뇌신경과학회 2021 Experimental Neurobiology Vol.30 No.6

Insomnia has become a common central nervous system disease. At present, the pathogenesis of insomnia is not clear. Animal models can help us understand the pathogenesis of the disease and can be used in transformational medicine. Therefore, it is very necessary to establish an appropriate model of insomnia. Clinical data show that insomnia patients with high levels of thyroxine and often accompanied by cardiovascular problems, a common mechanism underlying all of these physiological disruptions is the sympathetic nervous system. Combined with the characteristics of chronic onset of clinical insomnia, an insomnia model induced by long-term intraperitoneal injection of thyroid hormone has been created in our laboratory. In this paper, the insomnia-like state of the model was evaluated based on three validity criteria. Face validity has been demonstrated in metabolism, the Morris water maze, electrocardiogram (ECG) and electroencephalogram (EEG). Structure validity has been proved by the results of targeted metabolomics. After treatment with diazepam, a commonly used clinical anti-insomnia drug, the above physiological and pathological disorders were reversed. The results of comprehensive analysis show that the established thyrotoxicosis-associated insomnia model meets the validity requirement to establish an appropriate animal model of insomnia. The model presented in this article might help to study pathogenetic mechanisms of clinical insomnia, as well as to test promising methods of insomnia treatment.

Fluoxetine Protects against Big Endothelin-1 Induced Anti-Apoptosis by Rescuing Kv1.5 Channels in Human Pulmonary Arterial Smooth Muscle Cells

FeiFeng Dai,ZhiFu Mao,Jun Xia,ShaoPing Zhu,ZhiYong Wu 연세대학교의과대학 2012 Yonsei medical journal Vol.53 No.4

Purpose: Pulmonary Kv channels are thought to play a crucial role in the regulation of cell proliferation and apoptosis. Previous studies have shown that fluoxetine upregulated the expression of Kv1.5 and prevented pulmonary arterial hypertension in monocrotaline-induced or hypoxia-induced rats and mice. The current study was designed to test how fluoxetine regulates Kv1.5 channels, subsequently promoting apoptosis in human PASMCs cultured in vitro. Materials and Methods: Human PASMCs were incubated with low-serum DMEM, ET-1, and fluoxetine with and without ET-1 separately for 72 h. Then the proliferation, apoptosis, and expression of TRPC1 and Kv1.5 were detected. Results: In the ET-1 induced group, the upregulation of TRPC1 and down regulation of Kv1.5 enhanced proliferation and anti-apoptosis,which was reversed when treated with fluoxetine. The decreased expression of TRPC1 increased the expression of Kv1.5, subsequently inhibiting proliferation while promoting apoptosis. Conclusion: The results from the present study suggested that fluoxetine protects against big endothelin-1 induced anti-apoptosis and rescues Kv1.5 channels in human pulmonary arterial smooth muscle cells, potentially by decreasing intracellular concentrations of Ca2+.

Flow-pattern identification around two rectangular cylinders with aspect ratio of 0.5 in tandem arrangement

Letian Yang,Zhifu Gu,Xuejun Zhao,Weimin Zhang 한국풍공학회 2013 Wind and Structures, An International Journal (WAS Vol.16 No.2

The flow around two rectangular cylinders with aspect ratio of 0.5 in a tandem arrangement, was investigated using pressure measurements (in a wind tunnel) and flow visualizations (in a water tunnel) in the range of P/h from 0.6 to 4.0. Four flow patterns were identified, and processes of shear layers wrapping around, the shear layer reattachment, vortices wrapping around and vortices impingement, were observed. Mean and rms pressure distributions, flow visualizations and Strouhal numbers were presented and discussed. The paper revealed that the variations of Strouhal numbers were associated with the shear layers or vortex interference around two cylinders.

Thermal Treatment and Decontamination of PCBs- or Dioxins-laden materials

( Alfons Buekens ),( Zhifu Qi ),( Tong Chen ),( Shengyong Lu ),( Xiaodong Li ),( J. H. Yan ),( Kefa Cen ) 한국폐기물자원순환학회 2023 I-CIPEC Vol.2012 No.0

Damage evaluation and prediction of steel box structures under internal blast

Shujian Yao,Zhifu Wang,Duo Zhang,Fangyun Lu,Nan Zhao,Yanjing Wang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.10

In this study, a rapid prediction method for the damage range evaluation of steel box structures under internal blast load was proposed. First, we carried out a dimensional analysis of the damage range, determined the main influencing factors, and built a predictive model. Then, a large number of numerical simulations were conducted with consideration of different steel grades, structural dimensions, plate thicknesses, and explosive weights. After that, according to the damage range data for all the working conditions obtained with the simulation, the failure mode diagrams were drawn on a dimensionless coordinate axis and a twodimensional dimensionless number coordinate system. Based on this, the damage range for different working conditions was observed, and empirical equations were proposed to quickly predict the damage range of the steel box structure during a blast load. Finally, the correctness of the proposed quick prediction method was verified through field blast experiments result.

Triptolide inhibits ovarian cancer cell invasion by repression of matrix metalloproteinase 7 and 19 and upregulation of E-cadherin

Hongxi Zhao,Zhifu Yang,Xiaohong Wang,Xianzhi Zhang,Meng Wang,Yukun Wang,Qibing Mei,Zhipeng Wang 생화학분자생물학회 2012 Experimental and molecular medicine Vol.44 No.11

Triptolide, a compound extracted from the traditional Chinese medicine preparation of Tripterygium wilfordii Hook F., has been reported to have anti-inflammatory and anti-cancer activities. However, its effect on ovarian cancer invasion is unknown. We observed that MMP7 and MMP19 expression increased in ovarian cancer tissue. Triptolide treatment inhibited the migration and invasion of ovarian cancer cells SKOV3 and A2780 at the concentration of 15 nM. We also observed that triptolide suppressed MMP7 and MMP19 promoter activity in a dose-dependent manner,down-regulating the expressions of these promoters on mRNA and protein level. Moreover, triptolide enhanced E-cadherin expression in ovarian cancer cells. In vivo, triptolide inhibited tumor formation and metastasis in nude mice, and suppressed MMP7 and MMP19 expression; it also enhanced E-cadherin expression in tumor in a dose-dependent manner. Over expression of MMP7 and MMP19, or suppression of E-cadherin expression partially abolished the inhibitory effect of triptolide on invasion of ovarian cancer cells. To summarize, triptolide significantly inhibited the migration and invasion of ovarian cancer cells by suppression of MMP7 and MMP19 and up-regulation of E-cadherin expression. This study shows that triptolide is a good candidate for the treatment of ovarian cancer and reduction of metastasis.

Low Cost and Simple PMMA Nozzle Fabrication by Laser Cutting and PDMS Curing Bonding

E. Cheng,Xue Yang,Zhifu Yin,Wei Hu,Lu Li 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.1

Electrohydrodynamic (EHD) printing can rapidly fabricate micro- or nano-scale lines without employment of any mask, which is suitable for small volume production in industrial applications. However, it is required that the nozzles should be disposable since they can easily be blocked by the un-cleaned ink. CO 2 laser is an excellent tool for fabrication of microtrenches in most of polymers with low-cost and high-speed. This paper presented a low-cost PMMA (Polymethyl methacrylate) nozzle fabrication method based on laser cutting and PDMS (Polydimethylsiloxane) curing bonding. The influence of thickness on the maximum stress and deformation rate of PMMA substrate was investigated to decrease the deformation of PMMA nozzle after laser cutting. To avoid stress concentration in PMMA nozzle after thermal bonding, PDMS curing bonding method was proposed. The effect of spin-coating speed on PDMS thickness was studied. The O 2 plasma conditions were optimized based on contact angle to improve the bonding strength of PMMA nozzle. The EHD printing experiments demonstrated the practicability of proposed nozzle fabrication method.