Search

KR crack growth resistance curve can be used to predict crack propagation behavior, estimate the crack component bearing capacity after the crack, so KR curve research occupies very important position in the fracture mechanics. Based on crack growth resistance KR test curve of 2060 - T8E30 lithium aluminum alloy under the same thickness for different width, studies have shown that under the same thickness, the influence of the width on the resistance curve of crack propagation can be neglected. Empirical equation of resistance curve of crack extension of the smaller width specimen is given. Extending the fitting equation to that of larger width, it can be found that it is highly coincided with the experimental results.

The concentration of trace and rare earth elements in 22 crude oil and five oilfield water samples, collected from Triassic Yanchang Formation and Jurassic Yanan Formation reservoirs in the Jiyuan Area of Ordos Basin, N China, was determined using inductively coupled plasma mass spectrometry (ICP‐MS) for the first time. The oil samples were analysed to classify the oils into family and to determine the origin and depositional environment of organic matter that yield the oils using trace elements. The REE chondrite‐normalized distribution patterns of the crude oils show light rare earth element (LREE) enrichment and right‐oblique curves. These patterns could be divided into two distinct types that were consistent with that of the upper continental crust (UCC) and lower continental crust (LCC) characterizing by negative Eu anomalies and positive Eu anomalies, respectively. The REE concentrations in coexisting water samples are less than those in crude oils by a factor of ten. Cluster analysis also classified the oil samples from the Ordos Basin into two main groups. Integrated analysis of Co/Ni, V/Ni and V/ (V + Ni) values suggests that the organic matter have more terrigenous source input and the palaeoenvironment was anoxic and slightly oxic conditions. This study differs from previous studies by using trace element analyses of crude oils to constrain oil‐source rock correlation. The results show that most of the crude oils in north Jiyuan area were derived from Chang 7 mudstones while those from Hongde area may be contributed by Chang 7 oil shales. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Previously, VpPR-10.1 was isolated and characterized from a cDNA library of a fungus-resistant accession of Chinese wild grape (Vitis pseudoreticulata). We found that expression of VpPR-10.1 is affected by the fungal pathogen Erysiphe necator. To investigate the biochemical basis of the nuclease activity of VpPR-10.1 and its role in antifungal resistance, we generated recombinant VpPR-10.1 as well as site-directed mutations targeting three conserved amino acid residues among plant PR-10 s: Lys55, Glu149, and Tyr151. We showed that wild-type recombinant VpPR-10.1 exhibits both RNase and DNase activities. Mutant VpPR10.1-Y151H essentially retained all these activities. In contrast, VpPR10.1-K55N, where Lys55 in the P-loop region is mutated to Asn, and VpPR10.1-E149G, where Glu149 is mutated to Gly, lost their nuclease activity, indicating that both residues play a critical role in catalyzing RNA and DNA degradation. Furthermore, VpPR10.1 and VpPR10.1-Y151H inhibited the growth of the cultured fungal pathogen Alternaria alternate. Through transient expression in grapevine, we also demonstrated that VpPR10.1-K55N and VpPR10.1-E149G compromised resistance to E. necator. Finally, we further found that VpPR-10.1 can lead to programmed cell death and DNA degradation when incubated with tobacco BY-2 suspension cells. We show here that Lys55 and Glu149, but not Tyr151, are required for the RNase, DNase and antifungal activities of VpPR-10.1. The strong correlation between the level of VpPR-10.1 nuclease activity and its antifungal property indicates that the former is the biochemical basis for the latter. Taken together, our experiments revealed that VpPR-10.1 is critical in mediating fungal resistance in grape, potentially playing a dual role by degrading pathogen RNA and inducing programmed death of host cells. [ABSTRACT FROM AUTHOR]

Aim: To determine the regulatory effects of recombinant human growth hormone (rhGH) on dipeptide transport (PepT1) in normal and severe scald rats., Methods: Male Sprague-Dawley rats with 30% total body surface area (TBSA) III degree scald were employed as the model. In this study rhGH was used at the dose of 2 IU/kg(-1)d(-1). An everted sleeve of intestine 4 cm long obtained from mid-jejunum was securely incubated in Kreb's solution with radioactive dipeptide (3H-glycylsarcosine, 3H-Gly-Sar, 10 microCi/ml) at 37 degrees C for 15 min to measure the effects of uptake and transport of PepT1 of small intestinal epithelial cells in normal and severe scald rats., Results: Abundant blood supply to intestine and mesentery was observed in normal and scald rats administered rhGH, while less supply of blood to intestine and mesentery was observed in rats without rhGH. Compared with controls, the transport of dipeptide in normal rats with injection of rhGH was not significantly increased (P=0.1926), while the uptake was significantly increased (P=0.0253). The effects of transport and uptake of PepT1 in scald rats with injection of rhGH were significantly increased (P=0.0082, 0.0391)., Conclusion: Blood supply to intestine and mesentery of rats was increased following injection of rhGH. The effects of uptake and transport of dipeptide transporters in small intestinal epithelial cells of rats with severe scald were markedly up-regulated by rhGH.

Aim: To determine the regulation effects of recombinant human growth hormone (rhGH) on dipeptide transporter(PepT1) in Caco-2 cells with normal culture and anoxia/reoxygenation injury., Methods: A human intestinal cell monolayer (Caco-2) was used as the in vitro model of human small intestine and cephalexin as the model substrate for dipeptide transporter (PepT1). Caco-2 cells grown on Transwell membrane filters were preincubated in the presence of rhGH in the culture medium for 4 d, serum was withdrawn from monolayers for 24 h before each experiment. The transport experiments of cephalexin across apical membromes were then conducted; Caco-2 cells grown on multiple well dishes (24 pore) with normal culture or anoxia/reoxygenation injury were preincubated with rhGH as above and uptake of cephalexin was then measured., Results: The transport and uptake of cephelaxin across apical membranes of Caco-2 cells after preincubation with rhGH were significantly increased compared with controls (P=0.045, 0.0223). Also, addition of rhGH at physiological concentration (34 nM) to incubation medium greatly stimulates cephalexin uptake by anoxia/reoxygenation injuried Caco-2 cells (P=0.0116), while the biological functions of PepT1 in injured Caco-2 cells without rhGH were markedly downregulated. Northern blot analysis showed that the level of PepT1 mRNA of rhGH-treated injured Caco-2 cells was greatly increased compared to controls., Conclusion: The present results of rhGH stimulating the uptake and transport of cephalexin indicated that rhGH greatly upregulates the physiological effects of dipeptide transporters of Caco-2 cells. The alteration in the gene expression may be a mechanism of regulation of PepT1. In addition, Caco-2 cells take up cephalexin by the Proton-dependent dipeptide transporters that closely resembles the transporters present in the intestine. Caco-2 cells represent an ideal cellular model for future studies of the dipeptide transporter.

Aim: To investigate the expression of human erythropoietin (hEpo) in 293 cell line using adeno-associated virus (AAV) vector, and provide information for its potential application in human gene therapy., Methods: The human Epo cDNA was inserted into the AAV cassettes, and recombinant adeno-associated virus (rAAV-EPO) vectors were generated by cotransfection methods without helper virus. The expression of hEpo was detected by RT-PCR and ELISA methods., Results: A recombinant adeno-associated virus expressing hEpo was constructed and generated successfully. Positive signal of mRNA was detected from 293 cells transduced with rAAV-EPO, and the hEpo level in supernatant reached 500 U/L., Conclusion: rAAV-EPO expressed biologically active hEpo effectively, suggesting that it is a suitable gene expression tool for further study in vivo experiments.