No abstract

The aim was to examine the role of exogenous hydrogen sulfide (H2S) on cardiac remodeling in post-myocardial infarction (MI) rats. MI was induced in rats by ligation of coronary artery. After treatment with sodium hydrosulfide (NaHS, an exogenous H2S donor, 56 μM/kg·day) for 42 days, the effects of NaHS on left ventricular morphometric features, echocardiographic parameters, heme oxygenase-1 (HO-1), matrix metalloproteinases-9 (MMP-9), type I and type III collagen, vascular endothelial growth factor (VEGF), CD34, and α-smooth muscle actin (α-SMA) in the border zone of infarct area were analyzed to elucidate the protective mechanisms of exogenous H2S on cardiac function and fibrosis. Forty-two days post MI, NaHS-treatment resulted in a decrease in myocardial fibrotic area in association with decreased levels of type I, type III collagen and MMP-9 and improved cardiac function. Meanwhile, NaHS administration significantly increased cystathionine γ-lyase (CSE), HO-1, α-SMA, and VEGF expression. This effect was accompanied by an increase in vascular density in the border zone of infarcted myocardium. Our results provided the strong evidences that exogenous H2S prevented cardiac remodeling, at least in part, through inhibition of extracellular matrix accumulation and increase in vascular density.

Magnesium cement-based straw board is made of chloride-oxy-magnesium concrete as gel phase, a new building material with straw as reinforcing phase. The effects of molar ratio of MgO and MgCl2on the static bending strength, softening coefficient and start time back to halogen moisture absorption of magnesium cement-based straw board are analyzed in detail. The result showed that,when n(MgO)/n(MgCl2)=7(molar ratio),the mechanical properties and water resistance are the best, hydration products at this time is dominated by 518 phase.

The reinforcement in concrete alters the pathway for chloride transporting and in turn causes the chloride concentration to accumulate faster near the reinforcement closest to the exposed surface. A mass conservation matrix equation under the non-stable diffusion based on the Fick’s second law was derived. Hereby, a numerical simulation method for predicting chloride concentration in concrete was established utilizing the compiled module based on FEA. The validity of the method was verified by the comparison with the analytical results. The proposed method has a wider applicability for predicting the service life of RC structures. And it can be applied flexibly to any complicated section shape of RC members with multi-boundary attacked by chloride and the reinforcement considered simultaneously.

According to the phenomenon of pavement cracking in low temperature in Northeast China, AC-13I and AK-13I of the two gradations, SBS, Methyl Cellulose fiber and steel fiber are adopted to research the mechanics parameters of reinforced asphalt mixture by Indirect tension test at minus 10 degrees centigrade entering on pavement material. Improvement of the low-temperature indirect tensile strength, stiffness and deformation capacity of asphalt mixture is analyzed and mechanisms are revealed. The results indicate that low-temperature crack resistance of steel fiber-reinforced AC-13I asphalt mixture is improved significantly, it is better for the cold area in Northeast.