PubMed · 368861
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H Meiners. 1978. [Basic technological principles of metallocramics (II)].. https://pubmed.ncbi.nlm.nih.gov/368861/
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An immobilized enzyme (pancreatic ribonuclease bound to porous titania) was investigated for the degradation of purified yeast ribonucleic acid as a substrate. The immobilized enzyme is active and stable in the pH range 4--8. Dependence of enzymatic activity on ionic strength, pH, temperature, fluid flow rate, and substrate concentration were investigated. A cumulative fluid residence time of 6 sec is sufficient for 50% substrate conversion at 25 degrees C and pH 7.0. The critical flow rate (i.e., the fluid flow rate necessary to remove film diffusion resistance) approximately doubles with each 10 degree C rise in reaction temperature. The critical flow rates obtained in this study are about 40 times greater than those obtained for a similar study on immobilized glucose oxidase. Arrhenius plots gave activation energies of -9.6 and -7.1 kcal/g mol at pH 4.6 and 7.0, respectively. The work reported herein is a bench-scale investigation of an immobilized enzyme with primary emphasis on the mass transfer and kinetic characteristics of the system. The rapid reaction rates obtainable at relatively low temperatures offer a potential alternative method of purifying yeast single cell protein (SCP) with miminum loss of desired protein. The key questions are how such a system would react in a yeast homogenate, what conditions in such a system must be controlled, and what type of immobilized reactor should be utilized, if such further work continued to show promise.
The amount of lead leached from various glazed ceramic was determined by extraction with 5% acetic acid for one hour at 85 degrees C. All commercial ceramic items, both domestic and imported, were below the FDA standard of 7 mg/liter lead in the extractant. On the other hand, almost 60% of the domestic homemade ceramic items exceeded FDA standards. Comparison with previous studies show significant reduction in lead leaching from commercial ceramic containers. However, homemade ceramic items continue to pose a potential hazard of excessive lead release.