Research on Brownout Characteristics of Helicopter Approach Flight Based on the Unsteady Momentum Source Model Coupled with DEM

Qing Li,Yong-jie Shi,Guohua Xu,Linbo Wu 한국항공우주학회 2023 International Journal of Aeronautical and Space Sc Vol.24 No.2

In order to numerically simulate the brownout phenomenon encountered by helicopters in a sandy environment, a new coupled method is established that takes into account the accuracy and efficiency of calculation. In this method, the computational fluid dynamics (CFD) method based on the unsteady momentum source model and the discrete-element method (DEM) based on discrete dynamics are coupled to deal with this two-phase flow problem. In order to verify the validity of the calculation method, the results were compared with available real aircraft brownout flight test results, the results of the RANS method based on overset grids, and the results of the viscous vortex particle method (VVPM). Then, by applying the established method, a numerical simulation of the brownout phenomenon of a typical helicopter approach maneuver was carried out. The results show that after maneuvering descent changes into near-ground forward flight, the sand cloud that is generated is widely distributed and has a lower concentration near the fuselage, and the overall particle saltation characteristics are similar to those at higher forward flight speeds. This means that the phenomenon of brownout is reduced for a certain period of time in the approach chosen in this paper.

Expression and Regulation of Transcription Factor FoxA2 in Chronic Rhinosinusitis With and Without Nasal Polyps

Qing Luo,Jia Zhang,Hongtian Wang,Fenghong Chen,Xi Luo,Beiping Miao,Xingmei Wu,Renqiang Ma,Xiangqian Luo,Geng Xu,Jianbo Shi,Huabin Li 대한천식알레르기학회 2015 Allergy, Asthma & Immunology Research Vol.7 No.5

Purpose: Chronic rhinosinusitis (CRS) is characterized by the excessive production of mucus. However, the molecular mechanism underlying mucin overproduction in CRS with or without nasal polyps (CRSwNP and CRSsNP, respectively) is poorly understood. This study was conducted to assess the importance of the transcription factor FoxA2 in mucin production and to investigate the targeting of FoxA2 as a potential therapeutic strategy for mucus hypersecretion in CRS patients. Methods: We enrolled 15 CRSwNP patients, 15 CRSsNP patients, and 10 normal controls in this study. The expression levels of FoxA2, MUC5AC, and MUC5B in inflamed and healthy nasal tissues were examined via immunohistochemistry and quantitative reverse transcription-polymerase chain reaction, and the levels of several proinflammatory cytokines in nasal secretions were measured via FlowCytomix analysis. In addition, the expression of MUC5AC and FoxA2 was determined in polyp-derived epithelial cells and NCI-H292 cells after in vitro stimulation. Results: FoxA2 was significantly down-regulated, and MUC5AC and MUC5B were significantly up-regulated in both the CRSwNP and CRSsNP patients compared to the controls (P<0.05), and the protein level of FoxA2 was negatively associated with the IL-6 level in the CRS patients (P<0.05). IL-6 significantly increased MUC5AC expression but inhibited FoxA2 expression in vitro (P<0.05). Transfection with a FoxA2 expression plasmid significantly decreased MUC5AC promoter activity (P<0.05) and inhibited IL-6-induced MUC5AC production (P<0.05). In addition, clarithromycin significantly alleviated IL-6-induced FoxA2 suppression and decreased MUC5AC expression in vitro (P<0.05). Conclusions: Our findings suggest that FoxA2 may be considered a therapeutic target for the modulation of mucus hypersecretion in CRS patients.

Fibulin2: a negative regulator of BMSC osteogenic differentiation in infected bone fracture healing

Li Shi-Dan,Xing Wei,Wang Shao-Chuan,Li You-Bin,Jiang Hao,Zheng Han-Xuan,Li Xiao-Ming,Yang Jing,Guo De-Bin,Xie Xiao-Yu,Jiang Ren-Qing,Fan Chao,Li Lei,Xu Xiang,Fei Jun 생화학분자생물학회 2023 Experimental and molecular medicine Vol.55 No.-

Bone fracture remains a common occurrence, with a population-weighted incidence of approximately 3.21 per 1000. In addition, approximately 2% to 50% of patients with skeletal fractures will develop an infection, one of the causes of disordered bone healing. Dysfunction of bone marrow mesenchymal stem cells (BMSCs) plays a key role in disordered bone repair. However, the specific mechanisms underlying BMSC dysfunction caused by bone infection are largely unknown. In this study, we discovered that Fibulin2 expression was upregulated in infected bone tissues and that BMSCs were the source of infection-induced Fibulin2. Importantly, Fibulin2 knockout accelerated mineralized bone formation during skeletal development and inhibited inflammatory bone resorption. We demonstrated that Fibulin2 suppressed BMSC osteogenic differentiation by binding to Notch2 and inactivating the Notch2 signaling pathway. Moreover, Fibulin2 knockdown restored Notch2 pathway activation and promoted BMSC osteogenesis; these outcomes were abolished by DAPT, a Notch inhibitor. Furthermore, transplanted Fibulin2 knockdown BMSCs displayed better bone repair potential in vivo. Altogether, Fibulin2 is a negative regulator of BMSC osteogenic differentiation that inhibits osteogenesis by inactivating the Notch2 signaling pathway in infected bone.

Fishbone Oscillations in the Experimental Advanced Superconductivity Tokamak

Liqing Xu,Liqun Hu,Yi Yuan,Yingying Li,Guo-Qiang Zhong,Hai-Qing Liu,Kaiyun Chen,Tong-Hui Shi,Yan-Min Duan 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.6

A fishbone oscillation was observed in the neutral beam injection plasma at Experimental Ad- vanced Superconductivity Tokamak (EAST). This m = 1/n = 1 (m, n: poloidal, toroidal mode numbers, respectively) typical internal kink mode travels in the ion-diamagnetism direction in the poloidal section with a rotation speed close to the ion diamagnetic drift frequency. A high thermal plasma beta and high amounts of energetic ions are necessary for the mode to develop. Fishbone oscillations can expel heavy impurities in the core, which favors sustaining a high-performance plasma. The born frequency of the fishbone oscillation is the ion diamagnetic drift frequency and the chirping down of the frequency during the initial growth phase is the result of a drop in ion- diamagnetic drift frequency. The excitation energy is thought to be due to the thermal plasma pressure gradient; however, the development of a fishbone oscillation is related to energetic ions. A fishbone oscillation was observed in the neutral beam injection plasma at Experimental Advanced Superconductivity Tokamak (EAST). This m = 1/n = 1 (m, n: poloidal, toroidal mode numbers, respectively) typical internal kink mode travels in the ion-diamagnetism direction in the poloidal section with a rotation speed close to the ion diamagnetic drift frequency. A high thermal plasma beta and high amounts of energetic ions are necessary for the mode to develop. Fishbone oscillations can expel heavy impurities in the core, which favors sustaining a high-performance plasma. The born frequency of the fishbone oscillation is the ion diamagnetic drift frequency and the chirping down of the frequency during the initial growth phase is the result of a drop in ion- diamagnetic drift frequency. The excitation energy is thought to be due to the thermal plasma pressure gradient; however, the development of a fishbone oscillation is related to energetic ions.

Some Observations of the Influence Factors on the Response of Pile Groups

Qian-qing Zhang,Shi-min Zhang,Fayun Liang,Qian Zhang,Fei Xu 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.6

A simplified approach for nonlinear analysis of the load-displacement response of pile groups embedded in multilayered soils is presented in this work. A hyperbolic model is used to capture the relationship between unit skin friction and pile-soil relative displacement developed along the pile-soil interface and the stress-displacement relationship developed at the pile end. Considering interactive effect among piles, the parameters related to the hyperbolic model of an individual pile in a group can be computed. As to the analysis of the response of pile groups, a highly effective iterative computer program is developed using the hyperbolic model of an individual pile in a group. The efficiency and accuracy of the present method is verified using a well-documented field test. Furthermore, a parametric study is conducted to capture the influence of pile spacing and number of piles on the load-settlement response of the pile groups connected to a rigid cap. The pile-group settlement ratio and the pile-group resistance ratio are analyzed to assess the interaction effect among individual piles.

Antinociceptive Effects of Prim-O-Glucosylcimifugin in Inflammatory Nociception via Reducing Spinal COX-2

( Liu Qing Wu ),( Yu Li ),( Yuan Yan Li ),( Shi Hao Xu ),( Zong Yong Yang ),( Zheng Lin ),( Jun Li ) 한국응용약물학회 2016 Biomolecules & Therapeutics(구 응용약물학회지) Vol.24 No.4

We measured anti-nociceptive activity of prim-o-glucosylcimifugin (POG), a molecule from Saposhnikovia divaricate (Turcz) Schischk. Anti-nociceptive or anti-inflammatory effects of POG on a formalin-induced tonic nociceptive response and a complete Freund``s adjuvant (CFA) inoculation-induced rat arthritis pain model were studied. Single subcutaneous injections of POG produced potent anti-nociception in both models that was comparable to indomethacin analgesia. Anti-nociceptive activity of POG was dose-dependent, maximally reducing pain 56.6% with an ED50 of 1.6 mg. Rats given POG over time did not develop tolerance. POG also time-dependently reduced serum TNFα, IL-1β and IL-6 in arthritic rats and both POG and indomethacin reduced spinal prostaglandin E2 (PGE2). Like indomethacin which inhibits cyclooxygenase-2 (COX-2) activity, POG dose-dependently decreased spinal COX-2 content in arthritic rats. Additionally, POG, and its metabolite cimifugin, downregulated COX-2 expression in vitro. Thus, POG produced potent anti-nociception by downregulating spinal COX-2 expression.

Transcription changes of a putative trehalose-6-phosphate synthase gene in response to hormone stimulation in Leptinotarsa decemlineata (Say)

Ji-Feng Shi,Qing-Yu Xu,Wen-Chao Guo,Guo-Qing Li 한국응용곤충학회 2016 Journal of Asia-Pacific Entomology Vol.19 No.3

Trehalosemetabolism is critical for production of ATP, provision of carbon source, and facilitation of carbohydrate absorption. Trehalose-6-phosphate synthase (TPS) is a rate-limiting enzyme in trehalose biosynthesis. In the present paper, a TPS gene (LdTPS)was cloned inLeptinotarsa decemlineata. At young larval instars, the expression levels of LdTPS were high just before and right after ecdysis, and were low at the mid instar stages. In the fourthinstar larvae, two peaks occurred at 24 h after ecdysis and at the wandering stage. In vitro midgut culture and an in vivo bioassay revealed that 20E stimulated LdTPS transcription. Conversely, a reduction of 20E by RNA interference (RNAi) of a prothoracicotropic hormone receptor gene LdTorso and an ecdysteroidogenesis gene LdSHD repressed LdTPS expression. Moreover, disruption of 20E signaling by knockdown of LdEcR, LdE75 and LdFTZ-F1 reduced LdTPS transcript levels. Similarly, in vitro culture and an in vivo bioassay showed that exogenous JH or JH analog methoprene and pyriproxyfen activated LdTPS expression. An increase in endogenous JH by RNAi of an allatostatin gene LdAS-C enhanced the transcription. In contrast, a decrease in JH by silencing of a JH biosynthesis gene LdJHAMT downregulated LdTPS expression. Moreover, knockdown of LdILP2 repressed LdTPS transcription. Therefore, LdTPS transcription is tuned by 20E, JH and ILP signaling pathways in L. decemlineata.

Correlation between Intravoxel Incoherent Motion Magnetic Resonance Imaging Derived Metrics and Serum Soluble CD40 Ligand Level in an Embolic Canine Stroke Model

Xiao-Quan Xu,Chen-Jiang Wu,Shan-Shan Lu,Qian-Qian Gao,Qing-Quan Zu,Xing-Long Liu,Hai-Bin Shi,Sheng Liu 대한영상의학회 2017 Korean Journal of Radiology Vol.18 No.5

Objective: To determine the relationship between intravoxel incoherent motion (IVIM) imaging derived quantitative metrics and serum soluble CD40 ligand (sCD40L) level in an embolic canine stroke model. Materials and Methods: A middle cerebral artery occlusion model was established in 24 beagle dogs. Experimental dogs were divided into low- and high-sCD40L group according to serum sCD40L level at 4.5 hours after establishing the model. IVIM imaging was scanned at 4.5 hours after model establishment using 10 b values ranging from 0 to 900 s/mm2. Quantitative metrics diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (f) of ischemic lesions were calculated. Quantitative metrics of ischemic lesions were normalized by contralateral hemisphere using the following formula: normalized D = Dstroke / Dcontralateral. Differences in IVIM metrics between the low- and high-sCD40L groups were compared using t test. Pearson’s correlation analyses were performed to determine the relationship between IVIM metrics and serum sCD40L level. Results: The high-sCD40L group showed significantly lower f and normalized f values than the low-sCD40L group (f, p < 0.001; normalized f, p < 0.001). There was no significant difference in D*, normalized D*, D, or normalized D value between the two groups (All p > 0.05). Both f and normalized f values were negatively correlated with serum sCD40L level (f, r = -0.789, p < 0.001; normalized f, r = -0.823, p < 0.001). However, serum sCD40L level had no significant correlation with D*, normalized D*, D, or normalized D (All p > 0.05). Conclusion: The f value derived from IVIM imaging was negatively correlated with serum sCD40L level. f value might serve as a potential imaging biomarker to assess the formation of microvascular thrombosis in hyperacute period of ischemic stroke.

Bombyx mori used as a fast detection model of liver melanization after a clinical drug – Acetaminophen exposure

Yue He,Xu Xu,Jianfeng Qiu,Weimin Yin,Yang-Hu Sima,Shi-Qing Xu 한국응용곤충학회 2020 Journal of Asia-Pacific Entomology Vol.23 No.1

Acetaminophen (APAP) is an effective and widely used analgesic. However, APAP overdose is the principal cause of acute liver failure (ALF) in many countries. Here, we report the phenomenon of liver melanization which occurred before APAP-induced ALF in mice. A melanic surface induced by APAP which was time- and dosedependent in the silkworm invertebrate model was observed. In addition, an APAP-induced acute tissue failure model (ATF) was established using a metabolic detoxification tissue fat body which simulated mouse liver. An investigation of the anabolic mechanism of melanin in experimental animals showed that dopaquinone and dopamine which were synthesized from tyrosine via dopa in silkworms were further metabolized to melanin, while in mice, epinephrine was synthesized via the dopamine branch and melanin was only synthesized via the dopaquinone branch. On this basis, it is proposed that melanin-metabolic levels in plasma could be used as an early diagnostic marker of APAP overdose and the black spots on insect epidermis could be used as a fast detection model of toxicity.

Follow-Up of 58 Traumatic Carotid-Cavernous Fistulas after Endovascular Detachable-Balloon Embolization at a Single Center

Xiao-Quan Xu,Sheng Liu,Qing-Quan Zu,Lin-Bo Zhao,Jin-Guo Xia,Chun-Gao Zhou,Wei-Zhong Zhou,Hai-Bin Shi 대한신경과학회 2013 Journal of Clinical Neurology Vol.9 No.2

Background and Purpose This study evaluated the clinical value of detachable-balloon embolization for traumatic carotid-cavernous fistula (TCCF), focusing on the frequency, risk factors, and retreatment of recurrence. Methods Fifty-eight patients with TCCF underwent transarterial detachable-balloon embolization between October 2004 and March 2011. The clinical follow-up was performed every 3months until up to 3 years postprocedure. Each patient was placed in either the recurrence group or the nonrecurrence group according to whether a recurrence developed after the first procedure. The relevant factors including gender, fistula location, interval between trauma and the interventional procedure, blood flow in the carotid-cavernous fistula, number of balloons, and whether the internal carotid artery (ICA) was sacrificed were evaluated. Results All 58 TCCFs were successfully treated with transarterial balloon embolization, including 7 patients with ICA sacrifice. Recurrent fistulas occurred in seven patients during the follow-up period. Univariate analysis indicated that the interval between trauma and the interventional procedure (p=0.006) might be the main factor related to the recurrence of TCCF. The second treatments involved ICA sacrifice in two patients, fistula embolization with balloons in four patients, and placement of a covered stent in one patient. Conclusions Detachable balloons can still serve as the first-line treatment for TCCFs and recurrent TCCFs despite having a nonnegligible recurrence rate. Shortening the interval between trauma and the interventional procedure may reduce the risk of recurrence.