Manganese reductive dissolution coupled to Sb mobilization in contaminated shooting range soil.

A "redox-stat" R bioreactor was employed to simulate moderately reducing conditions (+ 420 mV) in Sb-contaminated shooting range soils for approximately 3 months, thermodynamically favoring Mn(IV) reduction. The impact of moderately reducing conditions on elemental mobilization (Mn, Sb, Fe) and speciation [Sb(III) versus Sb(V); Fe/Fe] was compared to a control bioreactor R without a fixed redox potential. In both bioreactors, reducing conditions were accompanied by an increase in effluent Sb(V) and Mn(II) concentrations, suggesting that Sb(V) was released through microbial reduction of Mn oxyhydroxide minerals.

Are foetal ultrasonographic and maternal blood progesterone measurements near parturition reliable predictors of the time of birth in the domestic cat?

In cats, accuracy of parturition day prediction by ultrasonographic measurement of foetal structures is decreasing towards the end of gestation. Foetal measurements during the last days of pregnancy are scarce. We determined foetal biparietal, abdominal and eye diameter (BPD, AD and ED, respectively) by ultrasonography as well as maternal blood progesterone (P4) within five days of delivery to predict parturition date and calculate accuracy of prediction.

Meshless Animation of Fracturing Solids.

We present a new meshless animation framework for elastic and plastic materials that fracture. Central to our method is a highly dynamic surface and volume sampling method that supports arbitrary crack initiation, propagation, and termination, while avoiding many of the stability problems of traditional mesh-based techniques. We explicitly model advancing crack fronts and associated fracture surfaces embedded in the simulation volume.

Weakening of the interface between adjacent catalytic chains promotes domain closure in Escherichia coli aspartate transcarbamoylase.

Aspartate transcarbamoylase from Escherichia coli is a dodecameric enzyme consisting of two trimeric catalytic subunits and three dimeric regulatory subunits. Asp-100, from one catalytic chain, is involved in stabilizing the C1-C2 interface by means of its interaction with Arg-65 from an adjacent catalytic chain. Replacement of Asp-100 by Ala has been shown previously to result in increases in the maximal specific activity, homotropic cooperativity, and the affinity for aspartate (Baker DP, Kantrowitz ER, 1993, Biochemistry 32:10150-10158).