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Jian-Xin Shen,Xue-Fei Qin,Wei-Zhong Fei,Yun-Chong Wang 한국자기학회 2019 Journal of Magnetics Vol.24 No.2
Pulse width modulation (PWM) of voltage source inverter (VSI) is common for speed regulation of permanent magnet (PM) brushless direct-current (BLDC) motor drives. However, when the motor runs at high speed, the conventional PWM technique may become unfeasible due to the low carrier ratio of inverter, which makes the motor current distorted and the motor core loss increased significantly. In this paper, two control strategies, namely single pulse variable width (SPVW) and dual pulses variable width (DPVW), are introduced for the high-speed PM BLDC motor drives, and are comprehensively investigated. Finite element method (FEM) is employed to evaluate and compare the drive system performance when using the conventional PWM, and the proposed SPVW and DPVW, respectively. Influence of the control techniques, especially on the loss distribution, is revealed.
Jian-Feng Chen,Ming-Qi Chen,Yong-Kang Shen,Jian-Hua Shao,Xin-Xin Yang 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.3
In this paper, the axial compressive properties of cold-formed steel lipped channel stub columns strengthened by rebars or steel strips are experimentally studied. The experiment included two sections. A kind of columns with local buckling is reinforced longitudinally by steel strips at the web. The other is the columns with distorted buckling, which is reinforced longitudinally by steel bars at the curling edge. The failure mode, deformation characteristics, ultimate bearing capacity and load displacement curve of the specimen are obtained through the experiment. On the basis of the experiment, the calculation results of theoretical axial bearing capacity of cold-formed steel lipped channel stub columns in Chinese, North American and Australian code are compared and analyzed. Research indicates: First, the cold-formed steel lipped channel stub columns strengthened by steel bars or steel strips can effectively improve the compressive bearing capacity of the specimen. Secondly, when the initial stress ratio of specimen is less than 0.3, the reinforcement effect is ideal. Thirdly, the three standards don’t stipulate the calculation of theoretical bearing capacity of the specimen strengthened after loading, so there is a large deviation between the theoretical calculation value and the test value.
CXCL12-CXCR4 Promotes Proliferation and Invasion of Pancreatic Cancer Cells
Shen, Bo,Zheng, Ma-Qing,Lu, Jian-Wei,Jiang, Qian,Wang, Tai-Hong,Huang, Xin-En Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.9
Objective: CXCL12 exerts a wide variety of chemotactic effects on cells. Evidence indicates that CXCL12, in conjunction with its receptor, CXCR4, promotes invasion and metastasis of tumor cells. Our objective was to explore whether the CXCL12-CXCR4 biological axis might influence biological behavior of pancreatic cancer cells. Methods: Miapaca-2 human pancreatic cancer cells were cultured under three different conditions: normal medium (control), medium + recombinant CXCL12 (CXCL12 group), or medium + CXCR4-inhibitor AMD3100 (AMD3100 group). RT-PCR was applied to detect mRNA expression levels of CXCL12, CXCR4, matrix metalloproteinase 2 (MMP-2), MMP-9, and human urokinase plasminogen activator (uPA). Additionally, cell proliferation and invasion were performed using CCK-8 colorimetry and transwell invasion assays, respectively. Results: CXCL12 was not expressed in Miapaca-2 cells, but CXCR4 was detected, indicating that these cells are capable of receiving signals from CXCL12. Expression of extracellular matrix-degrading enzymes MMP-2, MMP-9, and uPA was upregulated in cells exposed to exogenous CXCL12 (P<0.05). Additionally, both proliferation and invasion of pancreatic cancer cells were enhanced in the presence of exogenous CXCL12, but AMD3100 intervention effectively inhibited these processes (P<0.05). Conclusions: The CXCL12-CXCR4 biological axis plays an important role in promoting proliferation and invasion of pancreatic cancer cells.
Lijian Shen,Chenglin Liu,Jian-xin Zhao,Yuexing Feng,Licheng Wang 한국지질과학협의회 2021 Geosciences Journal Vol.25 No.5
Two types of potash ores were sampled from the Mengyejing potash deposit (the MPD) which is the only ancient potash deposit ever found in China. Geochemical analyses, including Br, K, Mg and some heavy metals, were performed on those samples. The relatively consistent Br contents (141.42 to 763.67 ppm) in both bedded potash and veined potash ores show that the potashforming brine was likely derived from seawater. K contents and Br/Cl ratios of the veined potash ores are relatively high in contrast to bedded potash ores. The K/Br ratios of veined potash ores exhibit a positive correlation with Br contents, which is opposite to that of the bedded potash ore of the MPD and potassium-salts from the evaporation of modern seawater. The contents of heavy metals in veined potash ores are much higher than those of bedded potash ores in the MPD and potash in other evaporite basins of the world. Sr and S isotopic compositions of these two types of potash ores suggest that the brines for precipitating veined potash were formed by mixing of connate waters (seawater or/and continental freshwater) and hydrothermal fluids. The geochemical and petrological characteristics of the veined potash ores indicate that the brine for forming veined potash orebodies caused by dissolution of previous bedded potash orebodies by hydrothermal fluids. The veined potash orebodies were formed through a cooling process by which sylvite precipitated first prior to halite.
The Role of Short Chain Fatty Acids in Irritable Bowel Syndrome
Wenxi Jian,Jiali Wu,Shefeng Zhu,Linying Xin,Chaohui Yu,Zhe Shen 대한소화기 기능성질환∙운동학회 2022 Journal of Neurogastroenterology and Motility (JNM Vol.28 No.4
Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder that is characterized by abdominal pain and disordered bowel habits. The etiology of IBS is multifactorial, including abnormal gut-brain interactions, visceral hypersensitivity, altered colon motility, and psychological factors. Recent studies have shown that the intestinal microbiota and its metabolites short chain fatty acids (SCFAs) may be involved in the pathogenesis of IBS. SCFAs play an important role in the pathophysiology of IBS. We discuss the underlying mechanisms of action of SCFAs in intestinal inflammation and immunity, intestinal barrier integrity, motility, and the microbiota-gut-brain axis. Limited to previous studies, further studies are required to investigate the mechanisms of action of SCFAs in IBS and provide more precise therapeutic strategies for IBS.
Yu Du,Jian Guan,Ruijun Xu,Xin Liu,Weijie Shen,Yafeng Ma,Yuan He,Songdong Shen 한국조류학회I 2017 ALGAE Vol.32 No.4
Pyropia haitanensis (T. J. Chang et B. F. Zheng) N. Kikuchi et M. Miyata is one of the most commercially usefulmacroalgae cultivated in southeastern China. In red algae, the biosynthesis of terpenoids through 2-C-methyl-Derythritol4-phosphate (MEP) pathway can produce a direct influence on the synthesis of many biologically importantmetabolites. In this study, two genes of cDNAs, 1-deoxy-D-xylulose-5-phosphate synthase (DXS) and 1-deoxy-Dxylulose-5-phosphatereductase (DXR), which encoding the first two rate-limiting enzymes among MEP pathway werecloned from P. haitanensis. The cDNAs of P. haitanensis DXS (PhDXS) and DXR (PhDXR) both contained complete openreading frames encoding polypeptides of 764 and 426 amino acids residues, separately. The expression analysis showedthat PhDXS was significant differently expressed between leafy thallus and conchocelis as PhDXR been non-significant. Additionally, expression of PhDXR and its downstream gene geranylgeranyl diphosphate synthase were both inhibitedby fosmidomycin significantly. Meanwhile, we constructed types of phylogenetic trees through different algae and higherplants DXS and DXR encoding amino acid sequences, as a result we found tree clustering consequences basically in linewith the "Cavalier-Smith endosymbiotic theory." Whereupon, we speculated that in red algae, there existed only completeMEP pathway to meet needs of terpenoids synthesis for themselves; Terpenoids synthesis of red algae derivativesthrough mevalonate pathway came from two or more times endosymbiosis of heterotrophic eukaryotic parasitifer. Thisstudy demonstrated that PhDXS and PhDXR could play significant roles in terpenoids biosynthesis at molecular levels. Meanwhile, as nuclear genes among MEP pathway, PhDXS and PhDXR could provide a new way of thinking to researchthe problem of chromalveolata biological evolution.
Haiquan Liu,Jianing Rong,Yao Song,Guoqiong Shen,Wen Gu,Xin Liu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.6
We prepared a series of Gd2O3:Yb,Er,Ca (3/1/x mol.%, x represents the nominal concentration of Ca element including 0, 2, 3, 4, 5, 7, 10) upconversion nanoparticles (UCNPs) with regular morphology via a wet-chemical route. We observed a simultaneous enhancement of upconversion luminescence (UCL) emission of Gd2O3:Yb,Er after Ca2+ ions were doped. When the doping level of Ca2+ reaches its optimal concentrate at 5 mol.%, the red and green emissions increased by 6.3 and 11 times, respectively. The potential application of Gd2O3:Yb,Er,Ca material as a noninvasion optical thermometry based on FIR technique was investigated. The sensing of temperature at both high and room temperatures was realized by choosing different parameters. The absolute temperature sensitivity (S'a) of Gd2O3:Yb,Er nanoparticles at 293K reached 0.0875 K-1, whereas Gd2O3:Yb,Er, 5 mol.%Ca was chosen as sensor of high temperature due to its considerable Sa of 0.0060 K-1 at 573 K. The resultant UCNPs provided a new way for sensitive thermal detection at various target temperatures.
Xiang-Dang Du,Xin-Sheng Li,Gui-Qin Wang,Bao-An Cui,Su-Mei Zhang,Jian-Zhong Shen 대한수의학회 2007 JOURNAL OF VETERINARY SCIENCE Vol.8 No.3
Seventy Escherichia coli isolates recovered from diseased chickens diagnosed with colibacillosis in Henan Province, China, between 2004 and 2005 were characterized for antimicrobial susceptibility profiles via a broth doubling dilution method. Overall, the isolates displayed resistance to trimethoprim-sulfamethoxazole (100%), oxytetracycline (100%), ampicillin (83%), enrofloxacin (83%), and ciprofloxacin (81%), respectively. Among the phenicols, resistance was approximately 79% and 29% for chloramphenicol and florfenicol, respectively. Molecular detection revealed that the incidence rates of the floR, cmlA, cat1, cat2 and cat3 were 29, 31, 16, 13, and 0%, respectively. Additionally, 10% of the isolates were positive for both floR and cmlA. As these antimicrobial agents may potentially induce cross-resistance between animal and human bacterial pathogens, their prudent use in veterinary medicine is highly recommended.