Suitability of Soil Washed Sand as Fine Aggregates to Replace River Sand in the Concrete

This paper presents a study on suitability of replacing river sand with soil washed sand as fine aggregate in concrete. The study was based on a comparison of concrete performance produced from river sand and soil washed sand obtained from four locations in Sri Lanka; Homagama, Rathnapura, Anuradhapura and Bandarawela. Several standard tests including Sieve analysis, Slump test and Compressive strength were conducted in order to check the workability, particle size distribution and compressive strength of M25 grade concrete. From the test results, it was found that percentages of coarse sand, medium sand and fine sand present in soil washed sand are higher than that of river sand, while highly coarse sand percentage was higher for the soil samples extracted from Rathnapura and Bandarawela areas compared to river sand. Slump test results showed that the concrete produced from river sand has a lower slump value compared to that of concrete produced from soil washed sand, suggesting that washed soil sand could possess higher workability. Test results showed that specimen cubes have achieved the target strength of M25 grade concrete even though compressive strength of concrete produced from soil washed sand was about 10% lesser compared that of river sand at 7 days, 14 days and 28 days’ strength

Attenuated Inflammatory Response in Aged Mice Brains following Stroke

Background: Increased age is a major risk factor for stroke incidence, post-ischemic mortality, and severe and long-term disability. Stroke outcome is considerably influenced by post-ischemic mechanisms. We hypothesized that the inflammatory response following an ischemic injury is altered in aged organisms. Methods and Results: To that end, we analyzed the expression pattern of pro-inflammatory cytokines (TNF, IL-1a, IL-1b, IL-6), anti-inflammatory cytokines (IL-10, TGFb1), and chemokines (Mip-1a, MCP-1, RANTES) of adult (2 months) and aged (24 months) mice brains at different reperfusion times (6 h, 12 h, 24 h, 2 d, 7 d) following transient occlusion of the middle cerebral artery. The infarct size was assessed to monitor possible consequences of an altered inflammatory response in aged mice. Our data revealed an increased neuro-inflammation with age. Above all, we found profound age-related alterations in the reaction to stroke. The response of pro-inflammatory cytokines (TNF, and IL-1b) and the level of chemokines (Mip-1a, and MCP-1) were strongly diminished in the aged post-ischemic brain tissue. IL-6 showed the strongest age-dependent decrease in its post-ischemic expression profile. Anti-inflammatory cytokines (TGFb1, and IL-10) revealed no significant age dependency after ischemia. Aged mice brains tend to develop smaller infarcts. Conclusion: The attenuated inflammatory response to stroke in aged animals may contribute to their smaller infarcts. The results presented here highlight the importance of using aged animals to investigate age-associated diseases like stroke

Ischemic thresholds for gray and white matter: A diffusion and perfusion magnetic resonance study

Background and Purpose-Although gray matter (GM) and white matter (WM) have differing neurochemical responses to ischemia in animal models, it is unclear whether this translates into differing thresholds for infarction. We studied this issue in ischemic stroke patients using magnetic resonance (MR) techniques