Lost-in-Translation of Metabolic Effects of Inorganic Nitrate in Type 2 Diabetes: Is Ascorbic Acid the Answer?

Beneficial metabolic effects of inorganic nitrate (NO₃⁻) and nitrite (NO₂⁻) in type 2 diabetes mellitus (T2DM) have been documented in animal experiments; however, this is not the case for humans. Although it has remained an open question, the redox environment affecting the conversion of NO₃⁻ to NO₂⁻ and then to NO is suggested as a potential reason for this lost-in-translation. Ascorbic acid (AA) has a critical role in the gastric conversion of NO₂⁻ to NO following ingestion of NO₃⁻. In contrast to AA-synthesizing species like rats, the lack of ability to synthesize AA and a lower AA body pool and plasma concentrations may partly explain why humans with T2DM do not benefit from NO₃⁻/NO₂⁻ supplementation. Rats also have higher AA concentrations in their stomach tissue and gastric juice that can significantly potentiate gastric NO₂⁻-to-NO conversion. Here, we hypothesized that the lack of beneficial metabolic effects of inorganic NO₃⁻ in patients with T2DM may be at least in part attributed to species differences in AA metabolism and also abnormal metabolism of AA in patients with T2DM. If this hypothesis is proved to be correct, then patients with T2DM may need supplementation of AA to attain the beneficial metabolic effects of inorganic NO₃⁻ therapy.     

The oil film in elastohydrodynamic elliptical contacts

The effect of speed, load and geometry on the oil film thickness and shape, in a roller bearing with barrelled rollers, is demonstrated experimentally by means of optical interferometry. At fairly high dimensionless roller speeds, film thickness increase becomes inhibited. This observation is attributed to a truncated inlet oil meniscus, a similar condition having been observed elsewhere in a ball and plate machine.     

Investigating the Exchange-Coupling Interactionin Nanostructure Composite Particles of SrFe12O19and ZnFe2O4

Ferromagnetic SrFe₁₂O₁₉–ZnFe₂O₄ nanostructure composite particles were synthesized by co-precipitation of chloride salts, in different stoichiometric ratios, by addition of sodium hydroxide solution. The resulting precursors were heat treated at temperatures in the range 800–1200°C for 4 h. Exchange interactions of the nanostructure composite particles were studied by use of exchange-coupling theory and plots of magnetic hysteresis. On the basis of exchange-coupling theory, the exchange interaction can be improved by increasing the soft phase content within the hard matrix. As temperature and soft phase ratio increase, the exchange interaction increases because of exchange length enhancement. The modified Brown’s equation was also used to analyze the effects of exchange coupling on coercivity.