Fatigue Life Evaluation of Welded Joints Considering the Local Multiaxial Stress/Strain States and Numerically Determined Residual Stresses/Strains

Wei Shen,Renjun Yan,Xiaoxing Wang,Enqian Liu,Lin Xu 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.1

This paper puts forward a kind of calculation method of estimating fatigue crack initiation life by considering welding residual stresses as initial stresses. The numerical method could be used to quantitatively analyze the influence of residual stresses on the cumulative fatigue damage. In order to gain the distribution of weld-induced residual stresses, the FE analyses as well as measurements were carried out. Based on critical plane approach, analysis of damage parameters was performed considering both welding residual stress and biaxial loads. Subsequently, validity of the proposed numerical method is verified by analyzing fatigue test results for several typical welded joints. It is concluded that the result of the present method is closer to the experimental value than that obtained with empirical formula method in the estimation of fatigue crack initiation life of welded structures.

Genome-wide identification and expression analysis of the BTB domain-containing protein gene family in tomato

Jinhua Li,Xiaoxing Su,Yinlei Wang,Wei Yang,Yu Pan,Chenggang Su,Xingguo Zhang 한국유전학회 2018 Genes & Genomics Vol.40 No.1

BTB (broad-complex, tramtrack, and bric-abrac) family proteins are characterized by the presence of a protein–protein interaction BTB domain. BTB proteins have diverse functions, including transcriptional regulation, protein degradation, chromatin remodeling, and cytoskeletal regulation. However, little is known about this gene family in tomato (Solanum lycopersicum), the most important model plant for crop species. In this study, 38 BTB genes were identified based on tomato whole-genome sequence. Phylogenetic analysis of BTB proteins in tomato revealed that SlBTB proteins could be divided into at least 4 subfamilies. The SlBTB proteins contains 1–3 BTB domains, and several other types of functional domains, including KCTD (Potassium channel tetramerization domain-containing), the MATH (meprin and TRAF homology), ANK (Ankyrin repeats), NPR1 (nonexpressor of pathogenesis-related proteins1), NPH3 (Nonphototropic Hypocotyl 3), TAZ zinc finger, C-terminal Kelch, Skp1 and Arm (Armadillo/betacatenin- like repeat) domains are also found in some tomato BTB proteins. Moreover, their expression patterns in tissues/ stages, in response to different abiotic stress treatments and hormones were also investigated. This study provides the first comprehensive analysis of BTB gene family in the tomato genome. The data will undoubtedly be useful for better understanding the potential functions of BTB genes, and their possible roles in mediating hormone cross-talk and abiotic stress in tomato as well as in some other relative species.

RhGLP-1 (7-36) protects diabetic rats against cerebral ischemia-reperfusion injury via up-regulating expression of Nrf2/HO-1 and increasing the activities of SOD

Yi Fang,Xiaofang Liu,Libo Zhao,Zhongna Wei,Daoli Jiang,Hua Shao,Yannan Zang,Jia Xu,Qian Wang,Yang Liu,Ye Peng,Xiaoxing Yin 대한약리학회 2017 The Korean Journal of Physiology & Pharmacology Vol.21 No.5

The present study aimed to explore the neuroprotective effect and possible mechanisms of rhGLP-1 (7-36) against transient ischemia/reperfusion injuries induced by middle cerebral artery occlusion (MCAO) in type 2 diabetic rats. First, diabetic rats were established by a combination of a high-fat diet and low-dose streptozotocin (STZ) (30 mg/kg, intraperitoneally). Second, they were subjected to MCAO for 2 h, then treated with rhGLP-1 (7-36) (10, 20, 40 μg/kg i.p.) at the same time of reperfusion. In the following 3 days, they were injected with rhGLP-1 (7- 36) at the same dose and route for three times each day. After 72 h, hypoglycemic effects were assessed by blood glucose changes, and neuroprotective effects were evaluated by neurological deficits, infarct volume and histomorphology. Mechanisms were investigated by detecting the distribution and expression of the nuclear factor erythroid-derived factor 2 related factor 2 (Nrf2) in ischemic brain tissue, the levels of phospho-PI3 kinase (PI3K)/PI3K ratio and heme-oxygenase-1 (HO-l), as well as the activities of superoxide dismutase (SOD) and the contents of malondialdehyde (MDA). Our results showed that rhGLP-1 (7-36) significantly reduced blood glucose and infarction volume, alleviated neurological deficits, enhanced the density of surviving neurons and vascular proliferation. The nuclear positive cells ratio and expression of Nrf2, the levels of P-PI3K/PI3K ratio and HO-l increased, the activities of SOD increased and the contents of MDA decreased. The current results indicated the protective effect of rhGLP-1 (7-36) in diabetic rats following MCAO/R that may be concerned with reducing blood glucose, up-regulating expression of Nrf2/HO-1 and increasing the activities of SOD.

RhGLP-1 (7-36) protects diabetic rats against cerebral ischemia-reperfusion injury via up-regulating expression of Nrf2/HO-1 and increasing the activities of SOD

Fang, Yi,Liu, Xiaofang,Zhao, Libo,Wei, Zhongna,Jiang, Daoli,Shao, Hua,Zang, Yannan,Xu, Jia,Wang, Qian,Liu, Yang,Peng, Ye,Yin, Xiaoxing The Korean Society of Pharmacology 2017 The Korean Journal of Physiology & Pharmacology Vol.21 No.5

The present study aimed to explore the neuroprotective effect and possible mechanisms of rhGLP-1 (7-36) against transient ischemia/reperfusion injuries induced by middle cerebral artery occlusion (MCAO) in type 2 diabetic rats. First, diabetic rats were established by a combination of a high-fat diet and low-dose streptozotocin (STZ) (30 mg/kg, intraperitoneally). Second, they were subjected to MCAO for 2 h, then treated with rhGLP-1 (7-36) (10, 20, $40{\mu}g/kg$ i.p.) at the same time of reperfusion. In the following 3 days, they were injected with rhGLP-1 (7-36) at the same dose and route for three times each day. After 72 h, hypoglycemic effects were assessed by blood glucose changes, and neuroprotective effects were evaluated by neurological deficits, infarct volume and histomorphology. Mechanisms were investigated by detecting the distribution and expression of the nuclear factor erythroid-derived factor 2 related factor 2 (Nrf2) in ischemic brain tissue, the levels of phospho-PI3 kinase (PI3K)/PI3K ratio and heme-oxygenase-1 (HO-l), as well as the activities of superoxide dismutase (SOD) and the contents of malondialdehyde (MDA). Our results showed that rhGLP-1 (7-36) significantly reduced blood glucose and infarction volume, alleviated neurological deficits, enhanced the density of surviving neurons and vascular proliferation. The nuclear positive cells ratio and expression of Nrf2, the levels of P-PI3K/PI3K ratio and HO-l increased, the activities of SOD increased and the contents of MDA decreased. The current results indicated the protective effect of rhGLP-1 (7-36) in diabetic rats following MCAO/R that may be concerned with reducing blood glucose, up-regulating expression of Nrf2/HO-1 and increasing the activities of SOD.

Identification and Characterization of Ectoine Biosynthesis Genes and Heterologous Expression of the ectABC Gene Cluster from Halomonas sp. QHL1, a Moderately Halophilic Bacterium Isolated from Qinghai Lake

Derui Zhu,Jian Liu,Rui Han,Guoping Shen,Qifu Long,Xiaoxing Wei,Deli Liu 한국미생물학회 2014 The journal of microbiology Vol.52 No.2

The moderately halophilic bacterium Halomonas sp. QHL1was identified as a member of the genus Halomonas by 16SrRNA gene sequencing. HPLC analysis showed that strainQHL1 synthesizes ectoine in its cytoplasm. The genes involvedin the ectoine biosynthesis pathway were identifiedon the chromosome in the order ectABC. Subsequently, theectB gene from this strain was amplified by PCR, and theentire ectABC gene cluster (3,580 bp) was cloned using genomewalking. Analysis showed that the ectA (579 bp), ectB(1269 bp), and ectC (390 bp) genes were organized in a singletranscriptional unit and were predicted to encode threepeptides of 21.2 kDa, 46.4 kDa, and 14.7 kDa, respectively. Two putative promoters, a δ70-dependent promoter and aδ38-controlled promoter, as well as several conserved motifswith unknown function were identified. Individual ectA, ectB,and ectC genes, and the entire ectABC gene cluster were insertedinto the expression plasmid pET-28a(+) to generatethe recombinant plasmids pET-28a(+)-ectA, pET-28a(+)-ectB, pET-28a(+)-ectC and pET-28a(+)-ectABC, respectively. Heterologous expression of these proteins in Escherichiacoli BL21 (DE3) was confirmed by SDS-PAGE. The recombinantE. coli strain BL21 (pET-28a (+)-ectABC) displayeda higher salt tolerance than native E. coli cells but producedfar less ectoine than the wild-type QHL1 strain.