Prediction of tensile strength degradation of corroded steel based on in-situ pitting evolution

Yun Zhao,Qi Guo,Zizhong Zhao,Xian Wu,Ying Xing 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.3

Steel is becoming increasingly popular due to its high strength, excellent ductility, great assembly performance, and recyclability. In reality, steel structures serving for a long time in atmospheric, industrial, and marine environments inevitably suffer from corrosion, which significantly decreases the durability and the service life with the exposure time. For the mechanical properties of corroded steel, experimental studies are mainly conducted. The existing numerical analyses only evaluate the mechanical properties based on corroded morphology at the isolated time-in-point, ignoring that this morphology varies continuously with corrosion time. To solve this problem, the relationships between pit depth expectation, standard deviation, and corrosion time are initially constructed based on a large amount of wet-dry cyclic accelerated test data. Successively, based on that, an in-situ pitting evolution method for evaluating the residual tensile strength of corroded steel is proposed. To verify the method, 20 repeated simulations of mass loss rates and mechanical properties are adopted against the test results. Then, numerical analyses are conducted on 135 models of corrosion pits with different aspect ratios and uneven corrosion degree on two corroded surfaces. Results show that the power function with exponents of 1.483 and 1.091 can well describe the increase in pit depth expectation and standard deviation with corrosion time, respectively. The effect of the commonly used pit aspect ratios of 0.10–0.25 on yield strength and ultimate strength is negligible. Besides, pit number ratio α equating to 0.6 is the critical value for the strength degradation. When α is less than 0.6, the pit number increases with α, accelerating the degradation of strength. Otherwise, the strength degradation is weakened. In addition, a power function model is adopted to characterize the degradation of yield strength and ultimate strength with corrosion time, which is revised by initial steel plate thickness.

Static behavior of bolt connected steel-concrete composite beam without post-cast zone

Ying Xing,Yun Zhao,Qi Guo,Jin-feng Jiao,Qing-wei Chen,Ben-zhao Fu 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.38 No.4

Although traditional steel-concrete composite beams have excellent structural characteristics, it cannot meet the requirement of quick assembly and repair in the engineering. This paper presents a study on static behavior of bolt connected steel-concrete composite beam without post-cast zone. A three-dimensional finite element model was developed with its accuracy and reliability validated by available experimental results. The analysis results show that in the normal service stage, the bolt is basically in the state of unidirectional stress with the loss of pretightening can be ignored. Parametric studies are presented to quantify the effects of the post-cast zone, size and position of splicing gap on the behavior of the beam. Based on the studies, suggested size of gap and installation order were proposed. It is also confirmed that optimized concrete slab in mid-span can reduce the requirement of construction accuracy.

Enhancement of Virus-induced Gene Silencing in Tomato by Low Temperature and Low Humidity

Da-Qi Fu,Ben-Zhong Zhu,Hong-Liang Zhu,Hong-Xing Zhang,Yuan-Hong Xie,Wei-Bo Jiang,Xiao-Dan Zhao,Yun-Bo Luo 한국분자세포생물학회 2006 Molecules and cells Vol.21 No.1

Virus-induced gene silencing (VIGS) is an attractive reverse-genetics tool for studying gene function in plants. We showed that silencing of a phytoene desaturase (PDS) gene is maintained throughout TRV-PDSinoculated tomato plants as well as in their flowers and fruit and is enhanced by low temperature (15°C) and low humidity (30%). RT-PCR analysis of the PDS gene revealed a dramatic reduction in the level of PDS mRNA in leaves, flowers and fruits. Silencing of PDS results in the accumulation of phytoene, the desaturase substrate. In addition, the content of chlorophyll a, chlorophyll b and total chlorophyll in the leaves of PDS-silenced plants was reduced by more than 90%. We also silenced the LeEIN2 gene by infecting seedlings, and this suppressed fruit ripenning. We conclude that this VIGS approach should facilitate large-scale functional analysis of genes involved in the development and ripening of tomato.

Low-Temperature Scanning Near-Field Optical Microscope and Spectroscopy: Application in Quantum Well Device

Gengzhao XU,Xing ZHU,Hu Liang,Kay May Lau,Weihua ZHANG,Yun-Dong Qi 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.47 No.1

We have constructed a versatile low-temperature scanning near-field optical microscope (LTSNOM) with the capability of near-field imaging and spectroscopy, operating at liquid nitrogen (LN) temperature. A sample is illuminated either electronically or optically by introducing a laser beam through specially designed coaxial double lenses and an optical fiber. The detected optical signal is transmitted via a fiber tip to a photoelectric multiplier tube (PMT) or a spectrometer. Shear-force detection by using a tuning-fork technique is applied to maintain the tip-sample distance. A shearforce topographic image, an optical image and a local spectrum can be obtained simultaneously. The whole scanning head is enclosed inside a container which is immersed in liquid nitrogen in a storage Dewar during the measurement. We have used this LT-SNOM to study the electroluminescence (EL) properties of InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs), at both room temperature and liquid nitrogen temperature. Low-temperature experiments with the LT-SNOM show the stability of our construction and stable image acquisition at LN temperature. The results show that at room temperature the EL intensity distribution is quite inhomogeneous with islands like bright spots, and at LN temperature the EL intensity increased dramatically and the inhomogeneity reduced greatly. Furthermore, the near-field spectra show a peak at a higher photon energy at around 2.95 eV at low temperature, in addition to the 2.7 eV peak observed by far field at room temperature. The results indicate that the self-organized In rich regions play a key role in the EL properties of these LEDs, which act as radiation recombination centers. In conjunction with nearfield spectroscopy, the possible mechanism of this phenomenon is explained in terms of irradiative recombination in the MQWs, as well as the quantum-confined Starks effect.

Overexpression of miR-155-5p Inhibits the Proliferation and Migration of IL-13-Induced Human Bronchial Smooth Muscle Cells by Suppressing TGF-β-Activated Kinase 1/MAP3K7-Binding Protein 2

Yujia Shi,Xingli Fu,Qi Cao,Zhengdao Mao,Yi Chen,Yun Sun,Zhiguang Liu,Qian Zhang 대한천식알레르기학회 2018 Allergy, Asthma & Immunology Research Vol.10 No.3

Purpose: Molecular mechanisms leading to asthma is still ill-defined. Though the function of microRNAs (miRNAs) in asthma was previously reported, the involvement of miR-155 in important features of this disease remains unknown. The present study was designed to uncover the probable involvement of miR-155-5p in the proliferation and migration of IL-13-induced human bronchial smooth muscle cells (BSMCs) and the intrinsic regulatory mechanism. Methods: The effects of different concentrations of IL-13 on the proliferation and migration of BSMCs as well as the expression of miR-155-5p and its predicted target transforming growth factor (TGF)-β-activated kinase 1/MAP3K7-binding protein 2 (TAB2) were investigated. The effects of miR-155-5p on the proliferation and migration of interleukin (IL)-13-induced BSMCs was determined in vitro using BSMCs transfected with miR-155 mimic/inhibitor and induced by a high concentration of IL-13. The quantitative real-time polymerase chain reaction (qRT-PCR) was employed for determining the expression of miR-155-5p and TAB2. Western blotting was applied to analyze the expression of TAB2 at the protein level. Cell proliferation and migration were assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Transwell assays, respectively. Results: The proliferation and migration of BSMCs were dose-dependently increased with IL-13 treatment. Contrariwise, IL-13 dose-dependently inhibited the expression of miR-155-5p in BSMCs. Mechanistic studies showed that inhibition of miR-155-5p further promoted the stimulatory effects of IL-13, whereas overexpression of miR-155 significantly inhibited these effects. In silico studies and luciferase reporter assays indicated that TAB2 was a negatively regulated miR-155-5p target. Conclusions: These results suggested that miR-155-5p-inhibit the IL-13-induced proliferation and migration of BSMCs by targeting TAB2 and that the IL-13/miR-155/TAB2 pathway could serve as a therapeutic target for pulmonary diseases, especially asthma.

Higher-level Production of Ascomycin (FK520) by Streptomyces hygroscopicus var. Ascomyceticus Irradiated by Femtosecond Laser

Hai-shan Qi,Xing Xin,Shan-shan Li,Jian-ping Wen,Yun-lin Chen,Xiao-qiang Jia 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.4

Femtosecond laser irradiation technology was employed for the first time to improve the ascomycin (FK520)yield of Streptomyces hygroscopicus var. ascomyceticus NT2-11, which is an N-methyl-N-nitro-N-nitrosoguanidine (NTG)-induced strain derived from S. hygroscopicus (ATCC14891). The mutant FS35 with high and stable FK520 production capacity was then obtained in the optimal irradiation conditions (25 mW for 6 min) by the Titanium sapphire laser system (810 nm, 76 MHz, 150 fs). The FK520 production capacity of FS35 was 45% higher than that of the parental strain NT2-11. Moreover, under the optimal fermentation conditions, FK520 fermentation titer of FS35 reached 300 mg/L and the intrinsic kinetics of FS35 and NT2-11 were investigated comparatively in 3phases. The mathematical models provided a good description of FK520 fermentation process for both strains and valuable information for optimizing operation and pilotplant enlargement research. The comparative studies on parameters of the models confirmed the advantages in production and the decrease of substrate inhibition through femtosecond laser irradiation. Therefore, femtosecond laser irradiation provides a promising way to enhance the production of FK520 in S. hygroscopicus. Femtosecond laser irradiation technology was employed for the first time to improve the ascomycin (FK520)yield of Streptomyces hygroscopicus var. ascomyceticus NT2-11, which is an N-methyl-N-nitro-N-nitrosoguanidine (NTG)-induced strain derived from S. hygroscopicus (ATCC14891). The mutant FS35 with high and stable FK520 production capacity was then obtained in the optimal irradiation conditions (25 mW for 6 min) by the Titanium sapphire laser system (810 nm, 76 MHz, 150 fs). The FK520 production capacity of FS35 was 45% higher than that of the parental strain NT2-11. Moreover, under the optimal fermentation conditions, FK520 fermentation titer of FS35 reached 300 mg/L and the intrinsic kinetics of FS35 and NT2-11 were investigated comparatively in 3phases. The mathematical models provided a good description of FK520 fermentation process for both strains and valuable information for optimizing operation and pilotplant enlargement research. The comparative studies on parameters of the models confirmed the advantages in production and the decrease of substrate inhibition through femtosecond laser irradiation. Therefore, femtosecond laser irradiation provides a promising way to enhance the production of FK520 in S. hygroscopicus.

Metformin Attenuates Liver Fat Content: Finding from Schizophrenia Patients with Olanzapine-induced Weight Gain

Li Wang,Yu Chen,Yun-chuan Sui,Xing-qi Tan,Zhi Zhou,Ning Li,Le-ping Xu 대한정신약물학회 2020 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.18 No.1

Objective: This study was performed to evaluate the efficacy of metformin on liver fat content (LFC) in first episode schizophrenia patients with olanzapine-induced weight gain, and the relationship between the change of LFC and the other metabolic indices. Methods: In a double-blind study, the clinically stable inpatients with first-episode schizophrenia under olanzapine monotherapy who gained more than 7% of their baseline weight were randomly assigned to two groups; one with olanzapine plus metformin (1,000 mg/day) (metformin group) and the other with olanzapine plus placebo (placebo group) for 16 weeks. All patients continued to maintain the original olanzapine dosage. LFC was measured by magnetic resonance imaging at baseline and at the end of 16 weeks, respectively. At the same time, glucose and lipid metabolism, homeostasis model assessment of insulin resistance index (HOMA-IR) were measured respectively, analyzing the correlation between the change value of LFC and other indicators. Results: Over the 16-week study period, LFC value in metformin group decreased compared with baseline. LFC change across the 16-week treatment period was −2.91% for the metformin group and 0.59% for the placebo group, with a between-group difference of −3.5% (95% confidence interval, −6.08 to −0.93; p = 0.009). Compared to baseline, in the metformin group, triglyceride and HOMA-IR reduced significantly, while high density lipoprotein cholesterol increased significantly at weeks 16. There was positive correlation between LFC changes and triglycerides, HOMA-IR changes significantly. Conclusion: Metformin can significantly attenuate LFC in schizophrenia patients with olanzapine-induced weight gain. It may be related to the improvement of the part of the glucolipid metabolic indices

Overexpression of a Thellungiella halophila CBL9 Homolog, ThCBL9, Confers Salt and Osmotic Tolerances in Transgenic Arabidopsis thaliana

( Zhi Bin Sun ),( Xing Yun Qi ),( Ping Hua Li ),( Chun Xia Wu ),( Yan Xiu Zhao ),( Hui Zhang ),( Zeng Lan Wang ) 한국식물학회 2008 Journal of Plant Biology Vol.51 No.1

Effects of Ho, Mn Co-Doping on Ferroelectric Fatigue of BiFeO3 Thin Films

Shifeng Zhao,Jieyu Chen,Wenyu Xing,Qi Yun,Wei Gao,Chenghong Nie 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.4

Ho, Mn, and Ho, Mn co-doped BiFeO3 thin films were deposited on Pt (100)/Ti/SiO2/Si substrates using solution gelation. The ferroelectric fatigue properties were clearly improved after doping with Ho and Mn. The doped BiFeO3 thin film displayed more strongly increased ferroelectric, leakage current, and fatigue properties compared with the pure BiFeO3 thin film. Thus, the improved performance of the BiFeO3 thin films depends on the structural transformation and reduced oxygen vacancy concentration. The present work provides a feasible approach to enhance the ferroelectric and fatigue properties of BiFeO3-based thin films.

Efficacy and Safety of Bevacizumab in Chinese Patients with Metastatic Colorectal Cancer

Zhu, Li-Ming,Zhao, Ya-Zhen,Ju, Hai-Xing,Liu, Lu-Ying,Chen, Lei,Liu, Bi-Xia,Xu, Qi,Luo, Cong,Ying, Jie-Er,Yang, Yun-Shan,Zhong, Hai-Jun Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.16

Objective: To evaluate the efficacy and safety of bevacizumab in the treatment of patients with metastatic colorectal cancer (mCRC). Methods: In a single-center, observational study of 91 Chinese patients with mCRC who received bevacizumab in combination with chemotherapy was conducted. Objective response rates (ORRs), progression-free survival (PFS), overall survival (OS) and adverse events were recorded, and the relationships between various clinical factors and PFS or OS were evaluated by Cox proportional hazards models. Results: Treatment with bevacizumab and chemotherapy was effective and tolerable. Univariate analysis showed that PFS and OS were significantly associated with the Eastern Cooperative Oncology Group performance status (ECOG-PS) score, duration of bevacizumab exposure, and whether chemotherapy was continued after discontinuation of bevacizumab treatment. A multivariate analysis showed that the duration of bevacizumab exposure and whether chemotherapy was continued after discontinuation of bevacizumab were independent prognostic factors for PFS and OS. Conclusion: In Chinese mCRC population, the shorter the duration of exposure to bevacizumab and chemotherapy, the worse the prognosis is.