Water Corrodes Copper

According to a current concept, copper canisters of thickness 0.05 m will be safe for nuclear waste containment for 100,000 years. We show that more than 1 m copper thickness might be required for 100,000 years durability based on water exposures of copper for 20 h, 7 weeks, 15 years, and 333 years. An observed evolution of hydrogen which involves heterogeneous catalysis of molecular hydrogen, first principles simulations, thermodynamic considerations and corrosion product characterization provide further evidence that water corrodes copper resulting in the formation of a copper hydroxide. These findings cast additional doubt on copper for nuclear waste containment and other important applications.     

Removing the Active‐Site Flap in Lipase A from Candida antarctica Produces a Functional Enzyme without Interfacial Activation

A mobile region is proposed to be a flap that covers the active site of Candida antarctica lipase A. Removal of the mobile region retains the functional properties of the enzyme. Interestingly interfacial activation, required for the wild‐type enzyme, was not observed for the truncated variant, although stability, activity, and stereoselectivity were very similar for the wild‐type and variant enzymes. The variant followed classical Michaelis–Menten kinetics, unlike the wild type. Both gave the same relative specificity in the transacylation of a primary and a secondary alcohol in organic solvent. Furthermore, both showed the same enantioselectivity in transacylation of alcohols and the hydrolysis of alcohol esters, as well as in the hydrolysis of esters chiral at the acid part.     

Maturation of spatial delayed responses to auditory cues in kittens.

Tested 40 mongrel cage-reared kittens in 4 age groups (45, 60, 120, or 180 days) for locomotor delayed responses to auditory cues in a 2-choice situation. Each S was trained for 15 days (300 trials); delays of 5 different durations (0-27 sec) were randomly given in each session. Performance did not improve as a function of age. All groups showed some immediate capacity for the task, all improved with training, and in all ages more errors were made after longer than after shorter delays. The ability to remember the locus of a brief sound over short periods of time appears to be mature before weaning in kittens. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)