Aerodynamic admittances of bridge deck sections: Issues and wind field dependence

Zhang, Zhitian,Zhang, Weifeng,Ge, Yaojun Techno-Press 2017 Wind and Structures, An International Journal (WAS Vol.25 No.3

Two types of aerodynamic admittance function (AAF) that have been adopted in bridge aerodynamics are addressed. The first type is based on a group of supposed relations between flutter derivatives and AAFs. In so doing, the aero-elastic properties of a section could be used to determine AAFs. It is found that the supposed relations hold only for cases when the gust frequencies are within a very low range. Predominant frequencies of long-span bridges are, however, far away from this range. In this sense, the AAFs determined this way are of little practical significance. Another type of AAFs is based on the relation between the Theodorsen circulation function and the Sears function, which holds for thin airfoil theories. It is found, however, that an obvious illogicality exists in this methodology either. In this article, a viewpoint is put forward that AAFs of bluff bridge deck sections are inherently dependent on oncoming turbulent properties. This kind of dependence is investigated with a thin plate and a double-girder bluff section via computational fluid dynamics method. Two types of wind fluctuations are used for identification of AAFs. One is turbulent wind flow while the other is harmonic. The numerical results indicate that AAFs of the thin plate agree well with the Sears AAF, and show no obvious dependence on the oncoming wind fields. In contrast, for the case of bluff double-girder section, AAFs identified from the turbulent and harmonic flows of different amplitudes differ among each other, exhibiting obvious dependence on the oncoming wind field properties.

Cytosolic escape of mitochondrial DNA triggers cGAS-STING-NLRP3 axis-dependent nucleus pulposus cell pyroptosis

Zhang Weifeng,Li Gaocai,Luo Rongjin,Lei Jie,Song Yu,Wang Bingjin,Ma Liang,Liao Zhiwei,Ke Wencan,Liu Hui,Hua Wenbin,Zhao Kangcheng,Feng Xiaobo,Wu Xinghuo,Zhang Yukun,Wang Kun,Yang Cao 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-

Low back pain (LBP) is a major musculoskeletal disorder and the socioeconomic problem with a high prevalence that mainly involves intervertebral disc (IVD) degeneration, characterized by progressive nucleus pulposus (NP) cell death and the development of an inflammatory microenvironment in NP tissue. Excessively accumulated cytosolic DNA acts as a damage-associated molecular pattern (DAMP) that is monitored by the cGAS-STING axis to trigger the immune response in many degenerative diseases. NLRP3 inflammasome-dependent pyroptosis is a type of inflammatory programmed death that promotes a chronic inflammatory response and tissue degeneration. However, the relationship between the cGAS-STING axis and NLRP3 inflammasome-induced pyroptosis in the pathogenesis of IVD degeneration remains unclear. Here, we used magnetic resonance imaging (MRI) and histopathology to demonstrate that cGAS, STING, and NLRP3 are associated with the degree of IVD degeneration. Oxidative stress induced cGAS-STING axis activation and NLRP3 inflammasome-mediated pyroptosis in a STING-dependent manner in human NP cells. Interestingly, the canonical morphological and functional characteristics of mitochondrial permeability transition pore (mPTP) opening with the cytosolic escape of mitochondrial DNA (mtDNA) were observed in human NP cells under oxidative stress. Furthermore, the administration of a specific pharmacological inhibitor of mPTP and self-mtDNA cytosolic leakage effectively reduced NLRP3 inflammasome-mediated pyroptotic NP cell death and microenvironmental inflammation in vitro and degenerative progression in a rat disc needle puncture model. Collectively, these data highlight the critical roles of the cGAS-STING-NLRP3 axis and pyroptosis in the progression of IVD degeneration and provide promising therapeutic approaches for discogenic LBP.

Sensitivity and vibration reduction of buffeting induced resonance of hangers

Zhang, Zhitian,Zhang, Weifeng Techno-Press 2017 Wind and Structures, An International Journal (WAS Vol.25 No.1

Buffeting induced resonance (BIR) of hangers on long-suspension bridges is briefly reviewed, including mechanism and experimental verification. Taken the Xihoumen suspension bridge as a numerical example, sensitivities of the BIR of hangers to wind properties are investigated, including types of wind spectrum, turbulence intensity, and spacial coherence of wind fluctuations. Numerical simulations indicate that the BIR of hangers occur to both cases of different wind spectra, showing that it is insensitive to types of wind spectrum. On the other hand, it is found that the turbulence intensity affects buffeting of main cables almost in a linear manner, and so it does to the BIR of the hangers; however, the resonance factors, namely the ratio of the response of the hanger to that of the main cable, are little affected by the turbulence intensity. The spacial coherence of the wind fluctuations, although plays an important role on the buffeting responses of the main structure, has no substantial effects on the BIR of the hangers. Finally, replacement of steel strand with CFRP material has been verified as a very effective countermeasure against the BIR of hangers.

Aerodynamic admittances of bridge deck sections: Issues and wind field dependence

Zhitian Zhang,Weifeng Zhang,Yaojun Ge 한국풍공학회 2017 Wind and Structures, An International Journal (WAS Vol.25 No.3

Two types of aerodynamic admittance function (AAF) that have been adopted in bridge aerodynamics are addressed. The first type is based on a group of supposed relations between flutter derivatives and AAFs. In so doing, the aero-elastic properties of a section could be used to determine AAFs. It is found that the supposed relations hold only for cases when the gust frequencies are within a very low range. Predominant frequencies of long-span bridges are, however, far away from this range. In this sense, the AAFs determined this way are of little practical significance. Another type of AAFs is based on the relation between the Theodorsen circulation function and the Sears function, which holds for thin airfoil theories. It is found, however, that an obvious illogicality exists in this methodology either. In this article, a viewpoint is put forward that AAFs of bluff bridge deck sections are inherently dependent on oncoming turbulent properties. This kind of dependence is investigated with a thin plate and a double-girder bluff section via computational fluid dynamics method. Two types of wind fluctuations are used for identification of AAFs. One is turbulent wind flow while the other is harmonic. The numerical results indicate that AAFs of the thin plate agree well with the Sears AAF, and show no obvious dependence on the oncoming wind fields. In contrast, for the case of bluff double-girder section, AAFs identified from the turbulent and harmonic flows of different amplitudes differ among each other, exhibiting obvious dependence on the oncoming wind field properties.

Novel reassortant 2.3.4.4B H5N6 highly pathogenic avian influenza viruses circulating among wild, domestic birds in Xinjiang, Northwest China

Qian Zhang,Xindi Mei,Cheng Zhang,Juan Li,Nana Chang,Dilihuma Aji,Weifeng Shi,Yuhai Bi,Zhenghai Ma 대한수의학회 2021 Journal of Veterinary Science Vol.22 No.4

Background: The H5 avian influenza viruses (AIVs) of clade 2.3.4.4 circulate in wild and domestic birds worldwide. In 2017, nine strains of H5N6 AIVs were isolated from aquatic poultry in Xinjiang, Northwest China. Objectives: This study aimed to analyze the origin, reassortment, and mutations of the AIV isolates. Methods: AIVs were isolated from oropharyngeal and cloacal swabs of poultry. Identification was accomplished by inoculating isolates into embryonated chicken eggs and performing hemagglutination tests and reverse transcription polymerase chain reaction (RT-PCR). The viral genomes were amplified with RT-PCR and then sequenced. The sequence alignment, phylogenetic, and molecular characteristic analyses were performed by using bioinformatic software. Results: Nine isolates originated from the same ancestor. The viral HA gene belonged to clade 2.3.4.4B, while the NA gene had a close phylogenetic relationship with the 2.3.4.4C H5N6 highly pathogenic avian influenza viruses (HPAIVs) isolated from shoveler ducks in Ningxia in 2015. The NP gene was grouped into an independent subcluster within the 2.3.4.4B H5N8 AIVs, and the remaining six genes all had close phylogenetic relationships with the 2.3.4.4B H5N8 HPAIVs isolated from the wild birds in China, Egypt, Uganda, Cameroon, and India in 2016–2017, Multiple basic amino acid residues associated with HPAIVs were located adjacent to the cleavage site of the HA protein. The nine isolates comprised reassortant 2.3.4.4B HPAIVs originating from 2.3.4.4B H5N8 and 2.3.4.4C H5N6 viruses in wild birds. Conclusions: These results suggest that the Northern Tianshan Mountain wetlands in Xinjiang may have a key role in AIVs disseminating from Central China to the Eurasian continent and East African.

Sensitivity and vibration reduction of buffeting induced resonance of hangers

Zhitian Zhang,Weifeng Zhang 한국풍공학회 2017 Wind and Structures, An International Journal (WAS Vol.25 No.1

Buffeting induced resonance (BIR) of hangers on long-suspension bridges is briefly reviewed, including mechanism and experimental verification. Taken the Xihoumen suspension bridge as a numerical example, sensitivities of the BIR of hangers to wind properties are investigated, including types of wind spectrum, turbulence intensity, and spacial coherence of wind fluctuations. Numerical simulations indicate that the BIR of hangers occur to both cases of different wind spectra, showing that it is insensitive to types of wind spectrum. On the other hand, it is found that the turbulence intensity affects buffeting of main cables almost in a linear manner, and so it does to the BIR of the hangers; however, the resonance factors, namely the ratio of the response of the hanger to that of the main cable, are little affected by the turbulence intensity. The spacial coherence of the wind fluctuations, although plays an important role on the buffeting responses of the main structure, has no substantial effects on the BIR of the hangers. Finally, replacement of steel strand with CFRP material has been verified as a very effective countermeasure against the BIR of hangers.

Pharmacokinetics, tissue distribution and excretion of peimisine in rats assessed by liquid chromatography-tandem mass spectrometry

Lihua Chen,Dongxun Li,Guosong Zhang,Wei Zhang,Lihua Zhang,Yongmei Guan,Weifeng Zhu,Hongning Liu 대한약학회 2015 Archives of Pharmacal Research Vol.38 No.6

Peimisine, the common ingredient of ‘‘zhebeimu’’groups and ‘‘chuanbeimu’’ groups, is responsiblefor the expectorant and cough relieving effects. The aim ofthis study was to investigate the pharmacokinetics, tissuedistribution and excretion of peimisine in male and femaleSD (Sprague-Dawley) rats by a rapid and sensitive LC-MS/MS (liquid chromatography-tandem mass spectrometry)method used carbamazepine as the internal standard afteroral administration, carbamazepine was stated as an IS. The results showed that peimisine was slowly distributed,and eliminated from rat plasma and manifested lineardynamics in a dose range of 0.26–6.5 mg/kg. Tested byANOVA, there were gender differences in the pharmacokineticparameters of AUC0-t, AUC0-? among a singledose of 0.26, 1.3, 6.5 mg/kg (P\0.05). Drug blood andtissue levels in male rats were significantly higher than thefemale counterparts after oral administration, while boththe males and the females showed high drug levels inspleen, kidney, lung, liver and heart. On the other hand, thepeimisine levels that can be reached in uterus, ovary, testisand brain is low. The excretion study showed that littleadministered peimisine (\0.7 %) was recovered in themale and female bile. Approximately 13.46 and 15.05 %were recovered in female urine and feces, while 43.07 and7.49 % were recovered in male urine and feces, respectively,which indicated that the major elimination route ofmale rats was urine excretion. In addition, there was significantdifferences in total cumulative excretive ratio ofpeimisine in feces (P\0.05) and no significant differencesin the urine (P[0.05) at a dose of 1.3 mg/kg.

Influences of genetically perturbing synthesis of the typical yellow pigment on conidiation, cell wall integrity, stress tolerance, and cellulase production in Trichoderma reesei

Zhang Weixin,An Ning,Guo Junqi,Wang Zhixing,Meng Xiangfeng,Liu Weifeng 한국미생물학회 2021 The journal of microbiology Vol.59 No.4

The prominent protein producing workhorse Trichoderma reesei secretes a typical yellow pigment that is synthesized by a gene cluster including two polyketide synthase encoding genes sor1 and sor2. Two transcription factors (YPR1 and YPR2) that are encoded in the same cluster have been shown to regulate the expression of the sor genes. However, the physiological relevance of the yellow pigment synthesis in T. reesei is not completely clear. In this study, a yellow pigment hyper-producer OEypr1 and three yellow pigment non-producers, OEypr1-sor1, Δypr1, and OEypr2, were constructed. Their phenotypic features in mycelial growth, conidiation, cell wall integrity, stress tolerance, and cellulase production were determined. Whereas hyperproduction of the yellow pigment caused significant defects in all the physiological aspects tested, the non-producers showed similar colony growth, but improved conidiation, maintenance of cell wall integrity, and stress tolerance compared to the control strain. Moreover, in contrast to the severely compromised extracellular cellobiohydrolase production in the yellow pigment hyperproducer, loss of the yellow pigment hardly affected induced cellulase gene expression. Our results demonstrate that interfering with the yellow pigment synthesis constitutes an engineering strategy to endow T. reesei with preferred features for industrial application.

Protective effect of Insect tea primary leaf (Malus sieboldii (Regal) Rehd.) extract on H2O2‑induced oxidative damage in human embryonic kidney 293T cells

Zhang Jing,Wang Hong,Yi Sha,Guo Zemei,Huang Yue,Li Weifeng,Zhao Xin,Liu Huazhi 한국응용생명화학회 2020 Applied Biological Chemistry (Appl Biol Chem) Vol.63 No.3

In this study, Insect tea primary leaf (Malus sieboldii (Regal) Rehd.) was used as the research object to investigate the protective effect of Insect tea primary extract (ITPLE) on hydrogen peroxide (H2O2)-induced oxidative damage in human embryonic kidney 293T cells (HEK 293T cells) and the mechanism of action of the main active components. The 3-(4,5-dimethyl-2-thiazolyl)- 2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay was used to determine the toxicity of ITPLE to HEK 293T cells in vitro as well as its protective effect against (H2O2)-induced oxidative damage in HEK 293T cells. In addition, various assay kits were used to measure oxidation-related indicators in HEK 293T cells, and quantitative polymerase chain reaction (qPCR) analysis was used to determine the mRNA expression levels of oxidation-related genes in HEK 293T cells. High performance liquid chromatography (HPLC) analysis was used to characterize active components in ITPLE. The experimental results revealed that the ITPLE had no toxic effect on cells in the range of 0–200 μg/mL, and, in this range, exhibited a concentration-dependent protective effect against H2O2- induced oxidative damage in HEK 293T cells. It was also found that the ITPLE can reduce the malondialdehyde (MDA) level and increase the levels of superoxide dismutase (SOD), glutathione (GSH), glutathione peroxidase (GSH-Px), and catalase (CAT)in oxidative damage HEK 293T cells. The qPCR analysis results also showed that the ITPLE upregulated the mRNA expression levels of SOD, CAT , GSH and GSH-Px in HEK 293T cells damaged by H2O2- induced oxidative stress. The HPLC analysis identified 7 bioactive components in the ITPLE, including neochlorogenic acid, cryptochlorogenic acid, rutin, kaempferin, isochlorogenic acid B, isochlorogenic acid A and hesperidin. This study reveals that ITPLE is rich in active compounds and has good antioxidant effect in vitro, thus it has the potential to be developed into a traditional Chinese medicine and functional drinks.

A Novel PCCM Voltage-Fed Single-Stage Power Factor Correction Full-Bridge Battery Charger

Zhang, Taizhi,Lu, Zhipeng,Qian, Qinsong,Sun, Weifeng,Lu, Shengli The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.3

A novel pseudo-continuous conduction mode (PCCM) voltage-fed single-stage power factor correction (PFC) full-bridge battery charger is proposed in this paper. By connecting a freewheeling transistor in parallel with an input inductor, the PFC cell can operate in the PCCM with a constant duty ratio. Thus, the dc/dc stage can be designed using this constant duty ratio and the restriction on the duty ratio of the PFC cell is eliminated. As a result, the input current distortion is less and the dc bus voltage becomes controllable over the wide output power range of the battery charger. Moreover, the operation principle of the dc/dc stage is designed to be similar to that of a conventional phase-shifted full-bridge converter. Therefore, it is easy to implement. In this paper, the operation of the new converter is explained, and the design considerations of the controller and key parameters are presented. Simulation and experimental results obtained from a 1 kW prototype are given to confirm the operation of the proposed converter.