Epidemiological risk factors for adult dengue in Singapore: an 8-year nested test negative case control study

10.1186/s12879-016-1662-4BMC Infectious Diseases16132

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Relationship of cytotoxic activity of natural killer cells to growth rates and serum zinc levels of female RIII mice fed zinc

This study examined a) the dietary zinc (Zn) requirement of RIII female weanling mice and b) the cytotoxicity of murine natural killer (NK) cells obtained from spleens of these mice fed varying levels of Zn. Zn was fed in a biotin-enriched egg albumen diet in amounts ranging from 0.9 to 40.4 μg/g diet. During a 28-day growth assay, maximum carcass growth was obtained with a diet containing 5.4 μg Zn/g diet. Maximal serum levels of Zn, however, were observed in mice fed diets containing 3.4 μg Zn/g diet. The cytotoxic activity of NK cells obtained from spleens of selected treatment groups was maximal at 40.4 μg Zn/g diet and was significantly higher (p ≤ 0.05) than that observed in spleens from mice fed diets that maximized carcass growth rates and serum Zn concentrations. It is concluded that female RIII mice have a dietary Zn requirement for growth similar to that observed for other murine strains but considerably lower than that reported for the rat. Our findings also suggest that RIII NK cells are particularly sensitive to dietary Zn intake: the optimal functional activity of these cells may result from intake of Zn higher than that necessary to maximize carcass growth and serum Zn concentrations

Use of Solid Wastes As Construction Materials

© 2014 by World Scientific Publishing Co. Pte. Ltd. All rights reserved. The use of solid wastes as construction materials is one way to address the global issue of sustainability and climate change. Many researchers and scientists have made significant contribution to turn wastes into useful resources. This chapter summarizes the publications of researchers who spent years of intensive effort to investigate certain important aspects of solid wastes utilization in construction. The solidwastes include, fly ash, timber industrial ash (TIA), palm oil fuel ash, expanded coal slag (ECS), foamed aggregate, waste styrofoam, and ground granulated blast furnace slag. The chemical composition, physical and engineering properties of the solid wastes and their effect on the performance of concrete, the most widely used construction material is briefly covered. Sustainable and viable options for infrastructure development are explored and discussed. The controlled density pervious lightweight concrete with high porosity allows water from precipitation and other sources to pass through it, thereby reducing the surface runofffrom going straight into the drain. The recharging of water into designated retention ponds are designed to minimize the fluctuation of groundwater levels. The study is to establish an economical method for construction on problematic soils especially on peat. The pervious low-carbon media with TIA has been studied on its potential for harvested rainwater treatment. The compressive strength development and water absorption of ECS concrete were presented in the ECS mix design nomograph that can be used to predict the dry density, compressive strength, and water absorption of various percentages of ECS concrete. The structural performance of reinforced concrete beams containing recycled crushed foamed concrete fine aggregate (RFA) is briefly covered. The cement industry contributes about 5% to global CO2 emissions from the calcination process of limestone and combustion of fuels in the kiln.A model of CO2 uptake by biomass silica foamed concrete is proposed as a potential mitigation strategy against CO2 emission. The proposed foamed concrete absorbs CO2 42.7% faster than the normal concrete. Successful deployment could contribute toward sustainable development while benefiting from the carbon credits