550 research outputs found

    On the boundary value problems of piecewise differential equations with left-right fractional derivatives and delay

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    In this paper, we study the multi-point boundary value problems for a new kind of piecewise differential equations with left and right fractional derivatives and delay. In this system, the state variables satisfy the different equations in different time intervals, and they interact with each other through positive and negative delay. Some new results on the existence, no-existence and multiplicity for the positive solutions of the boundary value problems are obtained by using Guo–Krasnoselskii’s fixed point theorem and Leggett–Williams fixed point theorem. The results for existence highlight the influence of perturbation parameters. Finally, an example is given out to illustrate our main results

    Isolation and characterization of cDNA encoding stilbene synthases from Chinese wild Vitis pseudoreticulata

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    mRNA differential display was employed to study powdery mildew disease resistance gene expression in Chinese wild Vitis pseudoreticulata 'Baihe-35-1' inoculated with Erysiphe necator (syn. Uncinula necator) under natural field conditions. A cDNA fragment T11AC/B0320-723 showing homology to stilbene synthase (STS) gene expressed more strongly at 1, 3, 5, 7 and 9 days after inoculation of leaves than in controls was found. The full cDNA length was cloned by rapid amplification of cDNA ends (RACE). Sequencing of the full length cDNA revealed cDNA sequences, sized 1288, 1411, 1468, 1492, 1506 and 1556 base pairs encoding 6 homologous polypeptides with 392 amino acid residues each, that were designated as VpSTS1, VpSTS2, VpSTS3, VpSTS4, VpSTS5 and VpSTS6 respectively. The deduced amino acid sequences shared identity of 65 %, 77 % and more than 94 % with Pinus strobus STS, Vitis vinifera chalcone synthase (CHS), and Vitis riparia, Vitis labrusca, Parthenocissus henryana, Cissus rhombifolia, Parthenocissus quinquefolia and Vitis vinifera STS, respectively.

    Protective Effects of Salvia miltiorrhizae on Multiple Organs of Rats with Obstructive Jaundice

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    Purpose. we aim to explore the protective effects of Salvia miltiorrhizae injection on multiple organs of obstructive jaundice (OJ) rats through observing the impact of this injection on the pathological alterations in these organs and the contents of endotoxin, PLA2, and TNF-α in the blood. Methods. A total of 90 mice were randomly divided into sham-operated group, model-control group, and Salvia miltiorrhizae-treated group (n = 30). According to the duration of postoperative administration, each group was further divided into two subgroups, namely, 21 d subgroup (consecutive administration for 21 d, n = 15) and 28 d subgroup (consecutive administration for 28 d, n = 15). After administration, the pathological alterations in multiple organs were observed and the contents of endotoxin, PLA2, and TNF-α in the blood were determined. Results. Compared to model control group, the number of dead rats in treated group decreased though there was no statistical difference between the two groups. The pathological alterations in the liver, kidney, and spleen in treated group showed varying degrees of mitigation. At all time points, the contents of plasma endotoxin declined significantly. On day 28, plasma PLA2 content in treated group was significantly lower than that in model-control group. Conclusion. Salvia miltiorrhizae injection is able to obviously reduce the contents of inflammatory mediators in the blood of OJ rats and exert some protective effects on multiple organs of these rats

    Effects of Hf, B, Cr and Zr alloying on mechanical properties and oxidation resistance of Nb-Si based ultrahigh temperature alloy

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    Multi-component Nb-Si based ultrahigh temperature alloys were prepared by vacuum non-consumable arc melting. The effects of Hf, B, Zr and Cr alloying on the phase selection, phase stability, both non-equilibrium and equilibrium microstructure, room-temperature fracture toughness, hardness and oxidation resistance at 1250 oC of the alloys have been investigated and estimated systematically. The results show that the addition of B or Cr promotes the formation of hypereutectic structures. The alloying with both Hf and B suppresses the formation of β(Nb,X)5Si3 and promotes the formation of α(Nb,X)5Si3 and γ(Nb,X)5Si3, while the alloying with Cr has no effect on the crystal structures of 5-3 silicides. The room-temperature fracture toughness of the alloys is always degraded by the addition of Cr but almost not influenced by the combined additions of Hf and B. The hardness of 5-3 silicides exhibits a tendency of γ \u3e α \u3e β. The macrohardness of the alloys increases with Cr addition, and it obviously reduces in the presence of Hf after 1450 oC/50 h heat-treatment. The best oxidation-resistant performance has been obtained for the alloy with both B and Cr additions. However, in the presence of B and/or Cr, the oxidation resistance of the alloys has been degraded by further addition of Hf. Both sizes and amounts of primary γ-(Nb, X)5Si3 increase with Zr contents in the alloy. Both adhesion and compactness of the scales are improved effectively by increase in Zr content. The mass gain and thickness of the scale decrease with increase in Zr contents, indicating that Zr addition can improve the oxidation resistance of the alloys significantly. Please click Additional Files below to see the full abstract

    Protection of Salvia miltiorrhizae to the Spleen and Thymus of Rats with Severe Acute Pancreatitis or Obstructive Jaundice

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    Objective. To investigate the therapeutic effects and mechanism of Salvia miltiorrhizae in the treatment of SAP and OJ. Methods. A total of 288 rats were used for SAP- and OJ-associated experiments. The rats were randomly divided into sham-operated group, model control group and treated group. The mortality rates of rats, contents of endotoxin and PLA2 in blood, patholodgical changes of different indexes in spleen and thymus were observed. Results. The contents of endotoxin and PLA2 in treated group were significantly lower than those in model control group.The pathological severity scores of spleen and thymus of SAP rats as well as that of spleen of OJ rats in treated groups were significantly lower than those in model control groups (P < .05). The staining intensity as well as the product of the staining intensity and positive rate of Bax protein of spleen in model control group were significantly higher than those in treated groups (P < .01) , and the apoptosis index of spleen in treated group was significantly lower than that in model control group (P < .01). Conclusion. Salvia miltiorrhizae exerts protective effects on the spleen and thymus of SAP rats and spleen of OJ rats
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