Surface -OH Profile from Reaction of a Heavy-Metal Fluoride Glass with Atmospheric Water

The surface -OH profile in a 15BaF₂-28.3ZnF₂-28.3YbF₂-28.3ThF₄ (mol%) glass resulting from reaction with atmospheric water for 22.5 h at 344°C was determined by monitoring the 2.9-pm absorption band as material was removed from the surface by polishing. The -OH penetrated -10 pm into the surface. The-OH concentration profile agreed with that predicted from a diffusional analysis, allowing determination of the surface -OH concentration; this corresponded to replacement of one of seven F⁻ ions with OH⁻.     

X-Ray Scattering Studies of Glasses in the System ZrF4-BaF2

A Fourier analysis of X-ray scattering by glasses in the system ZrF₄-BaF₂ is presented. The first peak in the radial distribution functions occurs in the range 0.209 to 0.211 nm; the average coordination numbers estimated for the zirconium atom are in the range 7.08 to 8.35, depending on the chemical composition. The second peak has been broken down into two components attributed to two kinds of Ba-F distances, 0.261 to 0.266 and 0.307 to 0.319 nm, with a corresponding coordination number of barium with respect to fluorine atoms ranging from 8.70 to 10.68. Interpretation of the cation-cation region is suggested; the average angle values of the Zr-F-Zr bridge bond, varying from 150° to 160° prevent two neighboring zirconium atoms from being bonded through two fluorine atoms. Comparative discussions with crystalline structures of fluorozirconates are presented.     

Protein Recovery from Veal Bones by Enzymatic Hydrolysis

Enzymatic hydrolysis (commercial enzyme) was applied to crushed bones in a batch reactor. The extraction was modeled using a Doehlert design. The effects of temperature (five levels ranging from 40 to 60°C), pH (seven levels from 5.7 to 7.5), enzyme concentration (seven levels from 20 to 80 g.kg^-1 protein), hydrolysis time (seven levels from 30 to 180 mn) and protein concentration (three levels from 60 to 90 g.kg^-1 mixture) were studied. Response surface methodology (RSM) predicted changes in protein yield and hydrolysis degree. Duration and enzyme concentration were the most important parameters, whereas pH and temperature exhibited no significant effects. Inhibition was observed over 80 g.kg^-1 of protein concentration.