Photo induced hydrogen evolution from water in the presence of EDTA and a supported catalyst

A flow reaction system was developed to study the steady state kinetics of hydrogen evolution in the presence of Ru(bipy)²⁺, MV⁺², EDTA and a heterogeneous supported catalyst. Under the conditions used, steady state rates similar to those previously reported with colloidal Pt particles were attained. Furthermore, over much of the range of concentrations used, the reaction was zero order and it did not exhibit an Arrhenius behavior. Examination of the various rate determining steps involved led us to conclude that surface processes such as the recombination and desorption of hydrogen from the Pt surface might be rate determining.     

Heat transfer enhancement by oscillatory perturbation of a stable separated flow

Numerical and experimental results for laminar flow and forced convection in a grooved channel indicate that significant heat transfer enhancement is possible by appropriately-tuned modulation of a steady, separated flow. The frequency r response of the enhancement is strongly peaked around the frequency of the least stable (decaying) mode of the unmodulated flow, suggesting that a simple resonance phenomenon is responsible for the transport augmentation.     

General solution of one-dimensional,time dependent coupled heat flow systems

A new, powerful method of analysis, involving the combined use of finite integral transform and finite element techniques, is presented for the solution of time dependent heat flow systems composed of many one-dimensional elements connected through the nodes. This method leads to an eigenvalue problem which is not of the conventional Sturm-Liouville type. A procedure for the determination of the eigenvalues is described. The solution obtained is in the form of an infinite series and contains quasi-steady and transient terms. The general solution obtained can be applied in the mathematical modelling of many engineering applications such as the determination of the penetration of the daily temperature cycle into buildings, the analysis of heat transfer in array of extended surfaces in compact heat exchangers, and many others.     

Gamma-Irradiation of Frozen Kiwifruit Pulp

Frozen (–18°C) de-seeded kiwifruit pulp (Actinidia deliciosa) was irradiated at a dose of 100 krad and stored at -18°C. Irradiation resulted in a 2.11 log₁₀ reduction in aerobic plate count (APC) with bacteria being most susceptible. Molds were less susceptible than yeasts. Assessments carried out over 6 months storage showed no significant differences in physical, chemical and sensory properties between irradiated and nonirradiated pulps. The microbial populations of the pulps decreased in parallel throughout the storage period. Frozen storage without irradiation resulted in a 3 log₁₀ reduction in APC over the 6 months period, a 38% reduction in ascorbic acid, and a slight loss of color. Three days frozen storage (– 18°C) following irradiation resulted in an APC only 0.89 log₁₀ higher than 6 months frozen storage (- 18°C) without irradiation with potential savings in energy and holding times which could have economic benefits.     

Effect of vitamins A, E and K on the indices of the glutathione antiperoxide system in gingival tissues in periodontosis

Glutathione reductase is activated and the content of glutathione sulfhydryl groups is increased in the gingival tissue of patients afficted with parodontosis. The degree of alterations depends on the degree of the development and character of the disease. Application of antioxidant vitamin therapy (vitamins A, E and K) locally and per os normalizes the parameters under study and improves the status of the parodontium.     

Are guidelines for excision of melanoma pertinent?

BACKGROUND: The treatment of patients with unresectable liver tumours remains an unsolved clinical problem. Several methods of locoregional treatment have been developed. These methods rely mainly on direct thermal or chemical insults and consequently have their own inherent limitations in clinical usage. The 'ideal' treatment would combine the direct cytotoxic effects of chemical treatments with the relative predictability of thermal insults, without the associated complications. This study aims to investigate whether the direct chemical effect of electrolytic hepatic necrosis is associated with any heating effect, and if so, whether the temperature change is dose-dependent. METHODS: An electrolytic 'dose' sufficient to induce a localized zone of hepatic necrosis was delivered to the livers of rats and pigs via implanted platinum electrodes. RESULTS: The results showed that there was no significant temperature increase at low current levels (2-4 mA) in the rat liver. In the pig, there was a significant (P < 0.01) increase in temperature of 4.2 degrees C during electrolysis, when delivered at between 20 and 50 mA. However, such a small increase in temperature would have been insufficient to cause appreciable thermal necrosis. CONCLUSIONS: This study demonstrates that electrolysis-induced hepatic necrosis is produced without an increase in temperature; clearly cell death results from the direct effects of cytotoxic electrode products and an alteration of intracellular pH. Consequently, it is likely that as a method for ablating liver tumours, electrolysis should be associated with fewer complications than other forms of locoregional treatment.