Combinatorial molecular optimization of cement hydrates.

Despite its ubiquitous presence in the built environment, concrete's molecular-level properties are only recently being explored using experimental and simulation studies. Increasing societal concerns about concrete's environmental footprint have provided strong motivation to develop new concrete with greater specific stiffness or strength (for structures with less material). Herein, a combinatorial approach is described to optimize properties of cement hydrates. The method entails screening a computationally generated database of atomic structures of calcium-silicate-hydrate, the binding phase of concrete, against a set of three defect attributes: calcium-to-silicon ratio as compositional index and two correlation distances describing medium-range silicon-oxygen and calcium-oxygen environments. Although structural and mechanical properties correlate well with calcium-to-silicon ratio, the cross-correlation between all three defect attributes reveals an indentation modulus-to-hardness ratio extremum, analogous to identifying optimum network connectivity in glass rheology. We also comment on implications of the present findings for a novel route to optimize the nanoscale mechanical properties of cement hydrate.

Plasma glucose lowering effect of the wild Satureja khuzestanica Jamzad essential oil in diabetic rats: role of decreased gluconeogenesis.

This study was to evaluate the effect of the wild SKEO on activities and genes expression of hepatic Glycogen Phosphorylase (GP) and phosphoenolpyruvate carboxykinase (PEPCK) in normal and diabetic rats. The wild SKEO was orally administered at different doses (50 and 100 mg/kg/day) to normal as well as diabetic rats for 21 days. The levels of mRNA were determined using the quantitative real-time RT-PCR technique. The plasma glucose concentrations of diabetic rats receiving SKEO (100 mg kg(-1)) compared with diabetic control were significantly decreased. Hepatic GP activity and its mRNA levels of diabetic rats treated with SKEO moderately increased. The activity of hepatic PEPCK and its mRNA levels were significantly decreased in normal rats treated with SKEO (100 mg kg(-1)). The enhancement of PEPCK activity and its mRNA levels of diabetic treated rats with SEKO (100 mg kg(-1)) was significantly decreased compared with diabetic control. In conclusion, an excessive inhibition of PEPCK in liver of diabetic rats treated with the wild SKEO may contribute to the plasma glucose lowering action of SKEO that seems to be in relation with antioxidant properties of SKEO.