http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Shifeng Wang (검색결과 15 건)
- 무료
- 기관 내 무료
- 유료
-
Jiayue Wang,Yuwen Zhu,Hui Li,Sheng Liu,Shengnan Shen,Lei Wang,Shifeng Wen 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.4
Laser-based powder bed fusion (L-PBF) is an additive manufacturing (AM) technology that uses a high-energy–density laser to scan through a powder bed and completely melts the metal powder. The environment inside the printer chamber, including the flow field of the shielding gas and the spatter particles induced by laser–powder interactions, is essential for product quality. For the first time, this work built a full-size model of printer chamber, and numerically investigated the interaction between the shielding argon flow and the laser induced spatter particles with considering laser temperature. A full-size geometric model of a commercial L-PBF printer with a Gaussian heat source was constructed, as well as a movable particle-release source model for particle injection. The distribution of the argon flow field, the temperature field, and the trajectory and deposition of spatter particles, particularly above the workbench during the L-PBF process were quantitatively analyzed. The results show that the gas flow within 30 mm above the workbench is uniform, and in the upper region of the printer chamber, the flow field is disorderly. The laser can only induce high temperature and upward gas flow in a small region close to the workbench (the height less than 1.6 mm), and the laser induced velocity disturbance in rest regions of the L-PBF printer is negligible. Particles injected towards the outlet (ID4) are mostly blown into the outlet, and in the other four injection directions, more than 90% of spatter particles are deposited inside the printer chamber, especially more than 50% deposited on the workbench. Increasing the laser power (from 100 to 200 W) has little effect on particle deposition on the workbench. Results will be helpful for improving the L-PBF product quality.
-
-
Wang, Lijuan,Che, Keke,Liu, Zhonghong,Huang, Xianlong,Xiang, Shifeng,Zhu, Fei,Yu, Yu The Korean Society of Pharmacology 2018 The Korean Journal of Physiology & Pharmacology Vol.22 No.3
The purpose of the present work is to establish an ultra-minimal invasive percutaneous puncture inoculation method for a VX2 orthotopic lung cancer rabbit model with fewer technical difficulties, lower mortality of rabbits, a higher success rate and a shorter operation time, to evaluate the growth, metastasis and apoptosis of tumor by CT scans, necropsy, histological examination, flow cytometry and immunohistochemistry. The average inoculation time was 10-15 min per rabbit. The tumorbearing rate was 100%. More than 90% of the tumor-bearing rabbits showed local solitary tumor with 2-10 mm diameters after two weeks post-inoculation, and the rate of chest seeding was only 8.3% (2/24). The tumors diameters increased to 4-16 mm, and irregularly short thorns were observed 3 weeks after inoculation. Five weeks post-inoculation, the liquefaction necrosis and a cavity developed, and the size of tumor grew further. Before natural death, the CT images showed that the tumors spread to the chest. The flow cytometry and immunohistochemistry indicated that there was less apoptosis in VX2 orthotopic lung cancer rabbit model compared to chemotherapy drug treatment group. Minimal invasive percutaneous puncture inoculation is an easy, fast and accurate method to establish the VX2 orthotopic lung cancer rabbit model, an ideal in situ tumor model similar to human malignant tumor growth.
-
Shifeng Wu,Tao Jiang,Xingang Wang,Weiwei Wu,Fan Zhang 한국분자세포생물학회 2016 Molecules and cells Vol.39 No.4
Wound healing is a complex physiological process necessitating the coordinated action of various cell types, signals and microRNAs (miRNAs). However, little is known regarding the role of miRNAs in mediating this process. In the present study, we show that let-7c miRNA is decreased in heat-denatured fibroblasts and that inhibiting let-7c expression leads to the increased proliferation and migration of dermal fibroblasts, whereas the overexpression of let-7c exerts an opposite effect. Further investigation has identified heat shock protein 70 as a direct target of let-7c and has demonstrated that the expression of HSP70 in fibroblasts is negatively correlated with let-7c levels. Moreover, down-regulation of let-7c expression is accompanied by up-regulation of Bcl-2 expression and down-regulation of Bax expression, both of which are the downstream genes of HSP70. Notably, the knockdown of HSP70 by HSP70 siRNA apparently abrogates the stimulatory effect of let-7c inhibitor on heat-denatured fibroblasts proliferation and migration. Overall, we have identified let-7c as a key regulator that inhibits fibroblasts proliferation and migration during wound healing.
-
Study on sloshing simulation in the independent tank for an ice-breaking LNG carrier
Ding, Shifeng,Wang, Gang,Luo, Qiuming The Society of Naval Architects of Korea 2020 International Journal of Naval Architecture and Oc Vol.12 No.1
As the LNG carrier operates in ice covered waters, it is key to ensure the overall safety, which is related to the coupling effect of ice-breaking process and internal liquid sloshing. This paper focuses on the sloshing simulation of the ice-breaking LNG carrier, and the numerical method is proposed using Circumferential Crack Method (CCM) and Volume of Vluid (VOF) with two main key factors (velocity νx and force Fx). The ship motion analysis is carried out by CCM when the ship navigates in the ice-covered waters with a constant propulsion power. The velocity νx is gained, which is the initial excitation condition for the calculation of internal sloshing force Fx. Then, the ship motion is modified based on iterative computations under the union action of ice-breaking force and liquid sloshing load. The sloshing simulation under the LNG tank is studied with the modified ship motion. Moreover, an ice-breaking LNG ship with three-leaf type tank is used for case study. The internal LNG sloshing is simulated with three different liquid heights, including free surface shape and sloshing pressure distribution at a given moment, pressure curves at monitoring points on the bulkhead. This present method is effective to solve the sloshing simulation during ice-breaking process, which could be a good reference for the design of the polar ice-breaking LNG carrier.
-
Study on sloshing simulation in the independent tank for an ice-breaking LNG carrier
Ding, Shifeng,Wang, Gang,Luo, Qiuming The Society of Naval Architects of Korea 2020 International Journal of Naval Architecture and Oc Vol.12 No.-
As the LNG carrier operates in ice covered waters, it is key to ensure the overall safety, which is related to the coupling effect of ice-breaking process and internal liquid sloshing. This paper focuses on the sloshing simulation of the ice-breaking LNG carrier, and the numerical method is proposed using Circumferential Crack Method (CCM) and Volume of Vluid (VOF) with two main key factors (velocity νx and force Fx). The ship motion analysis is carried out by CCM when the ship navigates in the ice-covered waters with a constant propulsion power. The velocity νx is gained, which is the initial excitation condition for the calculation of internal sloshing force Fx. Then, the ship motion is modified based on iterative computations under the union action of ice-breaking force and liquid sloshing load. The sloshing simulation under the LNG tank is studied with the modified ship motion. Moreover, an ice-breaking LNG ship with three-leaf type tank is used for case study. The internal LNG sloshing is simulated with three different liquid heights, including free surface shape and sloshing pressure distribution at a given moment, pressure curves at monitoring points on the bulkhead. This present method is effective to solve the sloshing simulation during ice-breaking process, which could be a good reference for the design of the polar ice-breaking LNG carrier.
-
Jiang, Tao,Wang, Xingang,Wu, Weiwei,Zhang, Fan,Wu, Shifeng Korean Society for Molecular and Cellular Biology 2016 Molecules and cells Vol.39 No.4
Wound healing is a complex physiological process necessitating the coordinated action of various cell types, signals and microRNAs (miRNAs). However, little is known regarding the role of miRNAs in mediating this process. In the present study, we show that let-7c miRNA is decreased in heat-denatured fibroblasts and that inhibiting let-7c expression leads to the increased proliferation and migration of dermal fibroblasts, whereas the overexpression of let-7c exerts an opposite effect. Further investigation has identified heat shock protein 70 as a direct target of let-7c and has demonstrated that the expression of HSP70 in fibroblasts is negatively correlated with let-7c levels. Moreover, down-regulation of let-7c expression is accompanied by up-regulation of Bcl-2 expression and down-regulation of Bax expression, both of which are the downstream genes of HSP70. Notably, the knockdown of HSP70 by HSP70 siRNA apparently abrogates the stimulatory effect of let-7c inhibitor on heat-denatured fibroblasts proliferation and migration. Overall, we have identified let-7c as a key regulator that inhibits fibroblasts proliferation and migration during wound healing.
-
An In situ Forming Hydrogel Based on Photo-Induced Hydrogen Bonding
Jingyan Zhang,Shifeng Wang,Zeren Zhao,Dong Si,Haiou Zhou,Mingdi Yang,Xianbiao Wang 한국고분자학회 2020 Macromolecular Research Vol.28 No.12
Stimulus-induced in situ forming hydrogels possess the characteristics of easy management and minimal invasiveness via simple injection at target sites with a liquid and easy forming bulk gels. In the present study, a photoreactive monomer, N'-(2-nitrobenzyl)-N-acryloyl glycinamide (NBNAGA) was introduced to modify polyacrylamide (PAM) hydrogel preparation with stimuli responsiveness. Firstly, poly(acrylamide-co-N'-(2-nitrobenzyl)-N-acryloyl glycinamide), P(AM-co-NBNAGA), copolymer solution was prepared via reversible addition fragmentation chain transfer (RAFT) polymerization using the monomers mixture of AM, NBNAGA, and N,N'- methylene bis-acrylamide (BIS). The obtained polymer solution with viscous, transparent, and flowable appearance contained weak single hydrogen bonding and slight chemical crosslinking in a microscopic perspective. Secondly, without further purification, after irradiation using UV light at 365 nm, poly(acrylamide-co-N-acryloyl glycinamide) (P(AM-co-NAGA)) hydrogel conveniently in situ formed due to the cleavage of o-nitrobenzyl groups and the corresponding emergency of dual hydrogen bonding among “uncaged” dual amide moieties. P(AM-co-NAGA) hydrogel depicted both favorable temperature sensitivity and self-healing properties, then the heating induced in vitro release profiles of doxorubicin (DOX) was analyzed.
-
Xiuju Du,Xuandong Wang,Yun Chen,Shuyu Tian,Shifeng Lu 한국고분자학회 2018 Macromolecular Research Vol.25 No.6
In our previous work, an acidic homogenous polysaccharide TAPA1 purified from Tremella aurantialba and its acetylated derivative TAPA1-ac, deacetylated derivative TAPA1-deac and sulfated fractions TAPA1-s were obtained by chemical modification and their partially chemical characterization were investigated. In present work, the antioxidant activities of various polysaccharides, including TAPA1, and its three derivative fractions, were determined in terms of scavenging of superoxide anion radicals and hydrogen peroxide (H2O2) by using chemiluminescence measurements, and their activities of oxidative injury rehabilitation were assessed by using PC12 oxidative injury model induced with H2O2. In general, compared with TAPA1, TAPA1-ac showed significant antioxidant activities and higher oxidative injury protection effects, whereas TAPA1-deac and TAPA1-s showed lower effects. These findings seemed to suggest that antioxidant effects and rehabilitation effect of oxidative injury, relate to not only different substituted group, but also the content and the degree of substitution (DS) of acetyl group, indicating that acetylation of TAPA1 was an effective means of enhancing its antioxidant activity and rehabilitation effect.
-
Xiuju Du,Xuandong Wang,Yun Chen,Shuyu Tian,Shifeng Lu 한국고분자학회 2018 Macromolecular Research Vol.26 No.6
In our previous work, an acidic homogenous polysaccharide TAPA1 purified from Tremella aurantialba and its acetylated derivative TAPA1-ac, deacetylated derivative TAPA1-deac and sulfated fractions TAPA1-s were obtained by chemical modification and their partially chemical characterization were investigated. In present work, the antioxidant activities of various polysaccharides, including TAPA1, and its three derivative fractions, were determined in terms of scavenging of superoxide anion radicals and hydrogen peroxide (H2O2) by using chemiluminescence measurements, and their activities of oxidative injury rehabilitation were assessed by using PC12 oxidative injury model induced with H2O2. In general, compared with TAPA1, TAPA1-ac showed significant antioxidant activities and higher oxidative injury protection effects, whereas TAPA1-deac and TAPA1-s showed lower effects. These findings seemed to suggest that antioxidant effects and rehabilitation effect of oxidative injury, relate to not only different substituted group, but also the content and the degree of substitution (DS) of acetyl group, indicating that acetylation of TAPA1 was an effective means of enhancing its antioxidant activity and rehabilitation effect.
ScienceON
스콜라연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
