Extending the Boundaries of Mechanical Properties of Ti-Nb Low-Carbon Steel via Combination of Ultrafast Cooling and Deformation During Austenite-to-Ferrite Transformation

Xiangtao Deng,Tianliang Fu,Zhaodong Wang,Guohuai Liu,Guodong Wang,R. D. K. Misra 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.1

We underscore here a novel approach to extend the boundaries of mechanical properties of Ti-Nb low-carbon steel via combination of ultrafast cooling and deformation during austenite-to-ferrite transformation. The proposed approach yields a refined microstructure and high density nano-sized precipitates, with consequent increase in strength. Steels subjected to ultra-fast cooling during austenite-to-ferrite transformation led to 145 MPa increase in yield strength, while the small deformation after ultra-fast cooling process led to increase in strength of 275 MPa. The ultra-fast cooling refined the ferrite and pearlite constituents and enabled uniform dispersion, while the deformation after ultra-fast cooling promoted precipitation and broke the lamellar pearlite to spherical cementite and long thin strips of FexC. The contribution of nano-sized precipitates to yield strength was estimated to be ~247.9 MPa and ~358.3 MPa for ultrafast cooling and deformation plus ultrafast cooling processes. The nano precipitates carbides were identified to be (Ti, Nb)C and had a NaCl-type crystal structure, and obeyed the Baker-Nutting orientation relationship with the ferrite matrix.

Callus induction and plant regeneration from leaves of peony

Xiangtao Zhu,Xueqin Li,Wenjie Ding,Songheng Jin,Yan Wang 한국원예학회 2018 Horticulture, Environment, and Biotechnology Vol.59 No.4

Tree peony (Paeonia suffruticosa Andr.) is a valued ornamental plant. This study reports on peony callus induction, shoot organogenesis and plant regeneration using young peony leaves as explants. Various media containing diverse plant growth regulators were assessed for their potency in peony propagation. After exposure of dark-adapted leaf discs to 30 μmol m−2 s−1 of light, inoculation in Murashige and Skoog (MS) + 0.2 mg L−1 2,4-dichlorophenoxyacetic acid (2,4-D) + 0.2 mg L−1 a-naphthaleneacetic acid (NAA) + 3.0 mg L−1 thidiazuron (TDZ) medium resulted to the highest callus induction rate with values reaching up to 87.8%. We identified that MS + 0.2 mg L−1 NAA + 2.0 mg L−1 6-benzyladenine (6-BA) + 2.0 mg L−1 kinetin (KT), with a multiplication coefficient of 3.025, to be the optimal medium for further callus proliferation under light. Inoculation in MS + 2.0 mg L−16-BA + 0.2 mg L−1 NAA + 0.3 mg L−1 TDZ medium allowed 22.22% of callus cultures to differentiate into adventitious shoots, whereas a similar rate of root formation was detected when 1/2 MS + 0.1 mg L−1 NAA + 0.05 mg L−1 IBA + 30 g L−1 sucrose medium was used. Our findings provide important information on peony regeneration and present a new method for peony tissue culture that will potentially facilitate mass propagation and genetic engineering of peony plants.

Molecular Cloning, Characterization, and Expression Analysis of Chicken Δ-6 Desaturase

Kang, Xiangtao,Bai, Yichun,Sun, Guirong,Huang, Yanqun,Chen, Qixin,Han, Ruili,Li, Guoxi,Li, Fadi Asian Australasian Association of Animal Productio 2010 Animal Bioscience Vol.23 No.1

Long-chain polyunsaturated fatty acids (LC-PUFA) promote the development of brain and vision of the fetus, relieve inflammation, inhibit oral dysplasia of rumor cell, decrease the incidence of cardiovascular disease and regulate arrhythmia. ${\Delta}-6$ desaturase is the rate-limited enzyme in the desaturation process. This study reports the cloning, characterization and tissue expression of a ${\Delta}-6$ desaturase gene in the chicken. PCR primers were designed based on the predicted sequence of chicken ${\Delta}-6$ desaturase (accession number: XM421053) and used to isolate a cDNA fragment of 1,323 bp from chicken liver. Based on the 1,323 bp fragment an EST (BI390105) was obtained by BLAST. The EST and 5'nd of the 1,323 bp fragment were partially overlapped. Gene specific primers derived from the EST were used for amplification of the 5'nd. Another gene-specific primer derived from the 1,323 bp fragment was used for amplification of the 3'nd by 3'ACE. Then the three overlapping cDNA sequences obtained were assembled with DNAMAN software and a full-length ${\Delta}-6$ desaturase of 2,153 bp was obtained. The full-length cDNA contained an ORF of 1,335 bp with a 5'ntranslated region of 147 nucleotides followed by an ATG initiation codon. Stop codon TGA was at position 1,481-1,483 bp. The deduced amino acids shared an homology above 77% with bovine, mice, orangutan, rat and human. The protein sequence had three histidine-rich regions HDFGH (HisI region), HFQHH (HisII region) and HH (HisIII region), a cytochrome $b_{5}$-like domain containing a heme-binding motif and two transmembrane domains. Sequence analysis of the chicken genomic DNA revealed that the coding sequence of chicken ${\Delta}-6$ desaturase included 12 exons and 11 introns. Semi-quantitative RT-PCR showed that the ${\Delta}-6$ desaturase expression levels were in turn liver, spleen, pancreas, lung, breast muscle, heart, and abdominal fat. The expression of ${\Delta}-6$ desaturase in liver was significantly higher than that in breast muscle (p<0.01). The expression of ${\Delta}-6$ desaturase in lung was significantly higher than that in abdominal fat (p<0.01). This is the first clone of chicken ${\Delta}-6$ desaturase.

Predictor Variables’ Influence on Classification Outcome in Insurance Fraud Detection

Saliu Adam Muhammad,Xiangtao Chen,Liao Bo 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.5

In fraud detection paradigms, the role of predictor variables cannot be overemphasized particularly when analytical tools – such as statistical, machine learning and artificial intelligent tools are employed. These variables or attributes are used to organize records of data in database tables. The combination of the values of these attributes usually affects which class of a target variable a record or an observation would belong. In this paper, we propose an algorithm and employ spreadsheet ‘count’ ‘count if’ and ‘filtering’ functionalities (techniques) to take toll on how the individual attribute may affect the prediction of the class of an observation in an insurance dataset of 5000 observations. The analysis showed that indeed, the individual predictor attribute affects the outcome of the target variable (legal or fraudulent) differently.

Homicidal Poisoning of Heroin and Estazolam : Autopsy and Pathological Findings, Toxicological Analysis

Dan Liu,Shangxun Li,Xiangtao Ma,Jinxue Gao,Liang Xu,Jun He,Yuhong Li,Dan Yan,Yiwu Zhou,Qingming Wu 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.4

We reported an unusual homicidal case in which a 40-year-old woman was deceived into drinking a cup of milk that had 72 tablets of estazolam (2mg/tablet) dissolved in, and then being injected heroin aqueous solution on the right deltoid region by the criminal. At autopsy, pinpoint pupils and a new injection site on the right deltoid region were found. The pathologic pictures showed multiple patchy hemorrhages and considerable amounts of foreign amorphous substance with yellow appearance at the injection site. Some double refracting crystals with the forms of Maltese cross, acicular, rhomb or irregular were found by polarizing microscope, which may result from the diluent in heroin such as starch. Toxicological qualitative analysis by gas chromatography mass spectrometry (GC-MS) demonstrated the presence of benzodiazepine and morphine in blood and urine, and heroin in the injector left at scene. Quantitative analysis was also performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), providing the data on distribution of 6-monoacetylmorphine, morphine and estazolam in the woman’s body. And the cause of death was determined to polydrug heroin-related deaths due to the combined poisoning of heroin and estazolam. It taught a lesson that the determination of other drugs, particularly central nervous system depressants in heroin poisoning were quite important in forensic expertise.

Parallel numerical analysis of the failure characteristics of earthquake-induced landslides

Zhenzhen Yan,Xiaoping Du,Xiangtao Fan 한국지질과학협의회 2016 Geosciences Journal Vol.20 No.4

Earthquake-induced landslides are serious natural hazards that shocked us with tremendous casualties and great economic losses in many mountainous areas around the world. However, predicting and preventing the earthquake-induced landslides is very difficult due to the complicated relationship between seismic dynamics and coseismic landsliding. Comprehensive understanding of earthquake-induced landslides from the perspective of seismic dynamic mechanism remains inadequate at present. This study employs an elastoplastic spectral element method incorporating parallel computing and represents a realistic three-dimensional slope model via a semi-structured hexahedral mesh to investigate the dynamic failure characteristics of earthquake-induced landslides. Dynamic behaviours of slopes are simulated using a continuumbased approach with a Mohr-Coulomb yield criterion. Displacement fields are calculated using the shear strength reduction technique. Pseudo-static seismic loading is performed to assess the slope stability quantitatively and complex topography is taken into consideration. The Xinzhong landslide that occurred in Beichuan Country is one of destructively collapsing landslides triggered by the Wenchuan earthquake and is therefore selected as a case study for discussion. Three-dimensional visualization of the calculated results quantitatively demonstrated that the three-dimensional numerical model well reproduced the coseismic landsliding response and its essential dynamic failure pattern, which could not be purely captured by Geographic Information Systems (GIS) and Remote Sensing (RS) technologies and calculated using simply two-dimensional numerical model. The numerical results also showed that tensile and shear fractures had significant influences on the nature of the failed surface development. In addition, the presence of seismic loading in the slope could cause obvious disturbances for the slope stability. Comparative analysis indicated that the shear surface of the earthquake-induced slope was shorter and the tension crack surface was deeper than that of the normal gravity condition. Moreover, the landslide mainly occurred in the transition from the upper to lower part of the slope, indicating that the slope topography was one of the crucial factors resulting in slope failure. Although the model was constructed without the presence of a pre-existing failure surface, comparative analysis addressed that the failure surface obtained by the numerical simulation was in close agreement with that by the post-failure investigations. The results could provide insight into better understanding of the relationship between landslide and seismic dynamic mechanism. The study has practical significance for the effective prevention and mitigation of earthquake-induced landslide hazards.

Effect of Cr Doping on Oxidation Resistance and Oxidation Mechanism of TiC Reinforced Steel Matrix Composites: Experiments and First-Principles Calculations

Chengru Li,Xiaolin Li,Yanmei Li,Xiangtao Deng,Zhaodong Wang 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.11

Oxidation is an inevitable problem and accelerates the wear of materials under high temperature wear conditions. To enhancethe oxidation resistance of TiC particle–reinforced steel matrix composites (TiC-SMCs), the role of Cr on the oxidationmechanism of TiC-SMCs at 600 °C was investigated through experimentation and first-principles calculations in this work. The results indicated that the addition of 3 wt% Cr could induce a transformation from internal oxidation to external oxidationbecause the diffusion energy barrier of O atoms was increased from 0.66 to 0.91 eV. Furthermore, The adsorption ofthe Fe and O atoms was reduced via Cr addition. Consequently, the oxidation resistance of TiC-SMCs was improved andinternal oxidation was inhibited with increasing Cr content, where the oxidation rate coefficients of TiC-SMCs with 3 wt%and 0.3 wt% Cr content were 3.79 × 10−4 and 4.84 × 10−1 mg2cm−4 h−1, respectively. The present study would not onlyprovide the basic understanding for the role of Cr on oxidation behavior, but also contribute to the design of TiC reinforcedsteel matrix composites with excellent oxidation resistance.

Establishment and evaluation of a murine anb3-integrinexpressing cell line with increased susceptibility to Foot-and-mouth disease virus

Wei Zhang,Kaiqi Lian,Fan Yang,Yang Yang,Zhijian Zhu,Zixiang Zhu,Weijun Cao,Ruoqing Mao,Ye Jin,Jijun He,Jianhong Guo,Xiangtao Liu,Haixue Zheng 대한수의학회 2015 Journal of Veterinary Science Vol.16 No.3

Integrin anb3 plays a major role in various signaling pathways, cell apoptosis, and tumor angiogenesis. To examine the functions and rolesof anb3 integrin, a stable CHO-677 cell line expressing the murine anb3 heterodimer (designated as “CHO-677-manb3” cells) wasestablished using a highly efficient lentiviral-mediated gene transfer technique. Integrin subunits an and b3 were detected at the gene andprotein levels by polymerase chain reaction (PCR) and indirect immunofluorescent assay (IFA), respectively, in the CHO-677-manb3 cellline at the 20th passage, implying that these genes were successfully introduced into the CHO-677 cells and expressed stably. A plaque-formingassay, 50% tissue culture infective dose (TCID50), real-time quantitative reverse transcription-PCR, and IFA were used to detect the replicationlevels of Foot-and-mouth disease virus (FMDV) in the CHO-677-manb3 cell line. After infection with FMDV/O/ZK/93, the cell line showeda significant increase in viral RNA and protein compared with CHO-677 cells. These findings suggest that we successfully established a stableanb3-receptor-expressing cell line with increased susceptibility to FMDV. This cell line will be very useful for further investigation of anb3integrin, and as a cell model for FMDV research.

Study on the role of gga-miRNA-200a in regulating cell differentiation and proliferation of chicken breast muscle by targeting Grb2

Keren Jiang,Fengbin Yan,Meng Zhang,Fang Li,Donghua Li,Guirong Sun,Xiaojun Liu,Hong Li,Ruili Han,Ruirui Jiang,Zhuanjian Li,Xiangtao Kang 한국통합생물학회 2017 Animal cells and systems Vol.21 No.6

Growth factor receptor-bound protein 2 (Grb2) have been proved by a lot of studies playing a major role in cell proliferation and cell differentiation. However, the regulation of Grb2 expression by microRNAs (miRNAs) in chicken breast muscle still remains unknown. The expression profile of Grb2 was checked based on our previous RNA sequencing data and the Grb2 relative expression level in breast muscle of aged hens (55-week-old) was validated significantly higher than juvenile hens (20-week-old) using qRT-PCR. miRNAs that interact with Grb2 have been predicted in chicken and the relationship between the potential miRNA and Grb2 was verified using dual luciferase reporter assay in chicken DF1 cells. Dual-luciferase reporter assays results demonstrated that the expression of luciferase reporter gene linked with part sequence of the 3′UTR of chicken Grb2 gene was down-regulated by the overexpression of gga (Gallus Gallus)- miR-200a-3p in the DF1 cells, and the down-regulation behavior was abolished when the ggamiR- 200a-3p binding site in 3′UTR of Grb2 was mutated, indicating that gga-miR-200a can suppress the expression level of its target gene Grb2. Therefore, we concluded that the significantly increased expression level of Grb2 in the breast muscle of aged chicken can (at least partly can) be explained by the decreased expression of miR-200a, which reduced the inhibitory effect on Grb2. Taken together, these findings suggest that gga-miR-200a can suppress the expression level of its target gene Grb2 and might be involved in the cell differentiation and proliferation of chicken breast muscle through binding with the 3’UTR of Grb2.