Study on Improving Cavitation Performance of Centrifugal Pump by Perforation at the Front Cover Plate

Wang Dongwei,Liu Zailun,Han Wei 한국유체기계학회 2020 International journal of fluid machinery and syste Vol.13 No.4

To improve the cavitation performance of a centrifugal pump, the high-pressure liquid in the front pump cavity is introduced into the cavitation area on the back of the blade by perforated holes at the front cover of the impeller. Based on the RNG k-ε turbulence model and Zwart-Gerber-be1amri cavitation model, the numerical calculation and analysis of the cavitation flow field in the model before and after perforation under different cavitation numbers is carried out by FLUENT. The results show that: The perforation at the front cover plate can effectively improve the pressure value of the cavitation area on the back of the blade. To some extent, the change of pressure gradient restrains the development of cavitation. The perforation at the front cover plate can effectively reduce the integral value of the cavitation bubble in the passage, improve the flow passage conditions in the impeller passage, and reduce the blockage degree of the cavitation to the passage. At the same time, the fluctuation range of the cavitation volume in the impeller is small in a rotation cycle after the perforation. It can be seen that the way of perforation at the front cover plate can effectively improve the cavitation performance of the centrifugal pump.

Deformation performance analysis of thin plates based on a deformation decomposition method

Dongwei Wang,Kaixuan Liang,Panxu Sun 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.84 No.4

Thin plates are the most common spatially stressed members in engineering structures that bear out-of-plane loads. Therefore, it is of great significance to study the deformation performance characteristics of thin plates for structural design. By constructing 12 basic displacement and deformation basis vectors of the four-node square thin plate element, a deformation decomposition method based on the complete orthogonal mechanical basis matrix is proposed in this paper. Based on the deformation decomposition method, the deformation properties of the thin plate can be quantitatively analyzed, and the areas dominated by each basic deformation can be visualized. In addition, the method can not only obtain more deformation information of the structure, but also identify macroscopic basic deformations, such as bending, shear and warping deformations. Finally, the deformation properties of the bidirectional thin plates with different sizes of central holes are analyzed, and the changing rules are obtained.

Effect of Adjusting Balance Hole to Cavitation Area on Cavitation Performance of a Centrifugal Pump

Wang Dongwei,Liu Zailun,Han Wei,Fu You 한국유체기계학회 2021 International journal of fluid machinery and syste Vol.14 No.3

In this study, the cavitation flow field of a centrifugal pump with four different positions of balance holes was studied by experiment and simulation. The results show that: the critical cavitation number decreases first and then increases with the position, the critical cavitation numbers of positions 2, 3 and 4 are smaller than the original model, and the effect of improving cavitation performance is obvious. The input of the high-pressure liquid from the balance cavity increases the absolute pressure of the cavitation area, and changes the pressure gradient in the cavitation area, then the cavitation suppressed. The position of the balance hole has obvious influence on the axial force, positions 2 and 3 reduce the axial force and improve the stress condition of the centrifugal pump, while positions 1 and 4 increase the axial force. It can be concluded that the positions o 2, 3 and 4 can improve the cavitation performance, so the cavitation performance of the centrifugal pump can be significantly improved by setting balance holes along the 2, 3 and 4 lines, also the balance hole should be avoided at position 1.

Numerical investigation of the influence of structures in bogie area on the wake of a high-speed train

Dongwei Wang,Chunjun Chen,Zhiying He 한국풍공학회 2022 Wind and Structures, An International Journal (WAS Vol.34 No.5

The flow around a high-speed train with three underbody structures in the bogie area is numerically investigated using the improved delayed detached eddy simulation method. The vortex structure, pressure distribution, flow field structure, and unsteady velocity of the wake are analyzed by vortex identification criteria Q, frequency spectral analysis, empirical mode decomposition (EMD), and Hilbert spectral analysis. The results show that the structures of the bogie and its installation cabin reduce the momentum of fluid near the tail car, thus it is easy to induce flow separation and make the fluid no longer adhere to the side surface of the train, then forming vortices. Under the action of the vortices on the side of the tail car, the wake vortices have a trend of spanwise motion. But the deflector structure can prevent the separation on the side of the tail car. Besides, the bogie fairings do not affect the formation process and mechanism of the wake vortices, but the fairings prevent the low-speed fluid in the bogie installation cabin from flowing to the side of the train and reduce the number of the vortices in the wake region.

Ceramide kinase-mediated C1P metabolism attenuates acute liver injury by inhibiting the interaction between KEAP1 and NRF2

Dongwei Yuan,Li Qing,Lu Xing,Lan Jianfeng,Qiu Zhidong,Wang Xuehong,Wang Junnan,Zheng Xiaojiao,Chen Sifan,Zhang Chong,Jin Junfei 생화학분자생물학회 2024 Experimental and molecular medicine Vol.56 No.-

Acute liver injury is the basis of the pathogenesis of diverse liver diseases. However, the mechanism underlying liver injury is complex and not completely understood. In our study, we revealed that CERK, which phosphorylates ceramide to produce ceramide-1-phosphate (C1P), was the sphingolipid pathway-related protein that had the most significantly upregulated expression during acute liver injury. A functional study confirmed that CERK and C1P attenuate hepatic injury both in vitro and in vivo through antioxidant effects. Mechanistic studies have shown that CERK and C1P positively regulate the protein expression of NRF2, which is a crucial protein that helps maintain redox homeostasis. Furthermore, our results indicated that C1P disrupted the interaction between NRF2 and KEAP1 by competitively binding to KEAP1, which allowed for the nuclear translocation of NRF2. In addition, pull-down assays and molecular docking analyses revealed that C1P binds to the DGR domain of KEAP1, which allows it to maintain its interaction with NRF2. Importantly, these findings were verified in human primary hepatocytes and a mouse model of hepatic ischemia‒reperfusion injury. Taken together, our findings demonstrated that CERK-mediated C1P metabolism attenuates acute liver injury via the binding of C1P to the DGR domain of KEAP1 and subsequently the release and nuclear translocation of NRF2, which activates the transcription of cytoprotective and antioxidant genes. Our study suggested that the upregulation of CERK and C1P expression may serve as a potential antioxidant strategy to alleviate acute liver injury.

大学创业教育支持与导师制度对大学生创业意图影响关系中 :自我效能感的中介效果研究

Wang Zhicheng,Kang Dongwei,Yang Mi lin 부산대학교 중국연구소 2017 Journal of China Studies Vol.20 No.3

In the field of Chinese university students’ entrepreneurial intention, there is little previous studies concerns about the university educational support and entrepreneurial intention. In thi s research, we focus on whether the mentoring and university educational support have the positve effect to the sutdents’ entrepreneurial or not, the statistical population for the study includes the students from 4 universities in China. Among the 263 surveys distributed, 245 surveys were completed and usable. The relationship among the mentoring, university educational support, self-efficacy, and entrepreneurial intention are examined by the SPSS, AMOS, and Bootstrapping. Under the situation of mass entrepreneurship and innovation, the government and university should encourage their mind and good idea to become reality. So, how to develop their entrepreneurial intention is necessary to considered. In this research, the purpose of this study is to empirically investigate the effect of mentoring, university educational support on entrepreneurial intention in Chinese universities. The mediating role of self-efficacy in the relationship between mentoring, university educational support and entrepreneurial intention is analysed. The research results reveal that: firstly, mentoring, as well as university educational support has a positive significant relationship to self-efficacy. Secondly, Self-efficacy also positively relates to entrepreneurial intention. Thirdly, Self-efficacy mediated the relationship between mentoring, university educational support and entrepreneurial intention. Finally, Some practical recommendations to develop the entrepreneurial intention for Chinese university students were suggested. Since today’s youth are the potential entrepreneurs of the future, understanding their self-efficacy and entrepreneurial intention about contextual factors can be a contribution to the development for the literature, and an important step in designing a more effective policy mechanism in universities. Nowadays, reinforce the mentor system and university educational support for the graduates who have entrepreneurial intention is very necessary.

Discovery of the Early Paleozoic Akechukesai high-Mg diorites in the western segment of East Kunlun Orogenic Belt and its constraints on the mechanism of break-off from Proto-Tethys oceanic subducted slab

Chao Wang,Fengyue Sun,Dongwei Liu,Lei Zuo,Tuofei Zhao,Jiaming Yan 한국지질과학협의회 2022 Geosciences Journal Vol.26 No.1

High-Mg andesites (HMAs) and their cognate intrusive rocks constitute volumetrically very small proportions of the total earth, and are mainly distributed along the edges of convergent plates. Petrogenetic studies can provide possible solutions for discrepancies in the geodynamics and subduction zone evolution. This paper presents the first ever reports of the newly discovered high-Mg diorite in Akechukesai area, the western part of the East Kunlun Orogenic Belt, and provides a reference for the evolutionary history and subduction mechanism of the Proto-Tethys Ocean. Akechukesai high-Mg diorites yielded a weighted mean zircon U-Pb dating age of 427.3 ± 2.3Ma (Middle Silurian). Results of the geochemical analyses show that the high-Mg diorites were high-K calc-alkaline series with the SiO2 content ranging 50.40 to 55.41 wt%. They are characterized by high values of Mg# (67–77), high MgO (6.92–10.58 wt%), TiO2 (0.53–0.87 wt%), Cr (286–615 ppm), Ni (61–124 ppm), Ba (570–927 ppm) contents, and low FeOtotal/MgO ratios (0.54–0.89). Furthermore, they exhibit nearly flat right-declined rare-earth element (REE) patterns with slight LREE enrichment. The samples are enriched in large ion lithophile elements (e.g., Ba, Rb, and Th) and depleted in high field strength elements (e.g., Ta, Nb, and Ti). These geochemical features are analogous to the sanukitic high-Mg andesites. The mean value of the initial εHf(t) is –1.3, indicating that the source is enriched mantle. The values of Rb/Cs, Ba/La, and La/Sm ratios suggest that subducting sediments formed an important component of the magmatic source. The presence of water-bearing minerals such as amphibole and biotite indicate a water-rich and oxygen-rich primitive magma system. Petrogenetic analysis indicates that the Akechukesai high-Mg diorites probably formed by melts and aqueous fluids produced from partial melting of the subducting sediments interacting with mantle peridotites. We hypothesize that, after the closure of the Proto-Tethys Ocean Basin in the Middle Silurian, the deep subducted slab broke-off and formed a slab window, asthenospheric material upwelled heating the subducting sediments and causing them to melt. Thus, we suggest that the emplacement of the Akechukesai high-Mg diorites mark the commencement of post-collisional magmatism.

Acupuncture for Osteoporosis: a Review of Its Clinical and Preclinical Studies

Tian Yimiao,Wang Lili,Xu Tianshu,Li Rui,Zhu Ruyuan,Chen Beibei,Zhang Hao,Xia Bingke,Che Yiwen,Zhao Dandan,Zhang Dongwei 사단법인약침학회 2022 Journal of Acupuncture & Meridian Studies Vol.15 No.5

Acupuncture has gained growing attention in the management of osteoporosis (OP). However, a comprehensive review has not yet been conducted on the efficacy and challenges of acupuncture in preliminary research and clinical trials. Therefore, an extensive literature search was conducted using electronic databases, including PubMed (www.ncbi.nlm.nih.gov/pubmed), CNKI (www.cnki.net), and Web of Science, for studies published from the beginning of 2000 to the end of May 2022. Combinations of synonyms for OP, acupuncture, traditional Chinese medicine, clinical trial, preclinical study, and animal experiments were searched. A total of 290 papers were consulted, including 115 reviews, 109 clinical observations, and 66 preclinical studies. There is accumulating evidence to support the beneficial role of acupuncture in preserving bone quality and relieving clinical symptoms based on clinical and preclinical investigations. The top ten most commonly used acupoints are BL23, ST36, BL20, BL11, CV4, GV4, SP 6, KI3, BL18, and GB39. The underlying mechanisms behind the benefits of acupuncture may be linked with the regulation of the hypothalamic-pituitary-gonadal (adrenal) axis and activation of the Wnt/β-catenin and OPG/RANKL/RANK signaling pathways. In summary, strong evidence may still come from prospective and well-designed clinical trials to shed light on the potential role of acupuncture in preserving bone loss. Future investigations are needed to explore the potential underlying mechanisms, long-term clinical efficacy, and compliance of acupuncture in OP management.

Involvement of DJ-1 in the pathogenesis of intervertebral disc degeneration via hexokinase 2-mediated mitophagy

Lin Jialiang,Wang Longjie,Wu Yuhao,Xiang Qian,Zhao Yongzhao,Zheng Xuanqi,Jiang Shuai,Sun Zhuoran,Fan Dongwei,Li Weishi 생화학분자생물학회 2024 Experimental and molecular medicine Vol.56 No.-

Intervertebral disc degeneration (IDD) is an important pathological basis for degenerative spinal diseases and is involved in mitophagy dysfunction. However, the molecular mechanisms underlying mitophagy regulation in IDD remain unclear. This study aimed to clarify the role of DJ-1 in regulating mitophagy during IDD pathogenesis. Here, we showed that the mitochondrial localization of DJ-1 in nucleus pulposus cells (NPCs) first increased and then decreased in response to oxidative stress. Subsequently, loss- and gain-of-function experiments revealed that overexpression of DJ-1 in NPCs inhibited oxidative stress-induced mitochondrial dysfunction and mitochondria-dependent apoptosis, whereas knockdown of DJ-1 had the opposite effect. Mechanistically, mitochondrial translocation of DJ-1 promoted the recruitment of hexokinase 2 (HK2) to damaged mitochondria by activating Akt and subsequently Parkin-dependent mitophagy to inhibit oxidative stress-induced apoptosis in NPCs. However, silencing Parkin, reducing mitochondrial recruitment of HK2, or inhibiting Akt activation suppressed DJ-1-mediated mitophagy. Furthermore, overexpression of DJ-1 ameliorated IDD in rats through HK2-mediated mitophagy. Taken together, these findings indicate that DJ-1 promotes HK2-mediated mitophagy under oxidative stress conditions to inhibit mitochondria-dependent apoptosis in NPCs and could be a therapeutic target for IDD.

Isolation, Purification, and Identification of Taxol and Related Taxanes from Taxol-Producing Fungus Aspergillus niger subsp. taxi

( Dan Li ),( Dongwei Fu ),( Yue Zhang ),( Xueling Ma ),( Liguo Gao ),( Xiaohua Wang ),( Dongpo Zhou ),( Kai Zhao ) 한국미생물생명공학회(구 한국산업미생물학회) 2017 Journal of microbiology and biotechnology Vol.27 No.8

The content of taxol in the bark of yews is very low, and this is not affordable from the environmental point of view. Thus, it is a necessity to look for alternative sources of taxol production to solve its supply. Currently, a large portion of the taxol in the market comes from chemical semi-synthesis, but the semi-synthetic precursors such as baccatin III and 10- deacetyl-baccatin III are extracted from needles and twigs of yew trees. Taxol-producing fungi as a renewable resource is a very promising way to increase the scale of taxol production. Our group has obtained a taxol-producing endophytic fungus, Aspergillus niger subsp. taxi HD86-9, to examine if A. niger can produce the taxanes. Six compounds from the fermentation broth of strain HD86-9 were isolated and identified by ¹H NMR, ¹³C NMR, and ESI-MS. The results showed that the six compounds included four taxane diterpenoids (taxol, cephalomannine, baccatin III, and 10-deacetyl-baccatin III) and two non-taxane compounds (β-sitosterol and flavonoid isovitexin). The study verified that the taxanes can be produced by the A. niger, which is very important to taxol production via chemical semi-synthesis. Additionally, the finding is potentially very significant to solve the taxol semi-synthetic precursors extracted from needles and twigs of yew trees, and the precursor production can be easily increased through the culture condition optimization, genetic breeding, and metabolic engineering of the A. niger.