Influence of membrane physical state on the proton permeability of isolated lysosomes was assessed by measuring the membrane potential with 3,3'-dipropylthiadicarbocyanine iodide and monitoring their proton leakage with p-nitrophenol. Changes in the membrane order were examined by the steady-state fluorescence anisotropy of 1, 6-diphenyl-1,3,5-hexatriene. Both the membrane potential and proton leakage increased with fluidizing the lysosomal membranes by benzyl alcohol and decreased with rigidifying the membranes by cholesteryl hemisuccinate. The proton permeability increased to the maximum of 42% by the benzyl alcohol treatment and decreased to the minimum of 38.1% by the cholesteryl hemisuccinate treatment. Treating the lysosomes with protonophore CCCP increased the proton permeability by 58%. The effects of the membrane fluidization and rigidification can be reversed by rigidifying the fluidized membranes and fluidizing the rigidified membranes, respectively. The results indicate that the proton permeability of lysosomes increased and decreased with increasing and decreasing their membrane fluidity, respectively. Moreover, the lysosomal proton permeability did not alter further if the changes, either an increase or a decrease, in the fluidity exceeded some amount. The results suggest that the proton permeability of lysosomes can be modulated finitely by the alterations in their membrane physical state.
Sintered molybdenum is widely used in the industry as an electrode for smelting furnace of glass and refractory, the crucible of rare earth metallurgy, and the thimbles for producing seamless steel tube and so on because of its strength at elevated temperature, good thermal properties, low sputtering yields and resistance to swelling. These unique properties of molybdenum make it a good candidate as a refractory metal. However, its further applications were limited by the brittleness characteristic and therefore many new molybdenum alloys were developed for improving ductility, among which the oxide dispersion strengthened molybdenum alloy (ODS Mo) is especially of interest. The ODS Mo, prepared by adding a proper amount of rare earth oxides (La 2 O 3 , Y 2 O 3 etc.) and by deforming to a large amount, exhibits a much higher recrystallization temperature than commercial pure molybdenum, [1±6] which makes ODS Mo show not only superior non-sag property and creep resistance at high temperatures but also superior strength and ductility at low temperatures as compared with the pure molybdenum. [7±9] Many explanations have been suggested on the strengthen mechanism of oxide dispersion strengthened molybdenum alloy. Hiraoka et al. attributed the improvement of low-temperature brittleness to the elongated coarse grain structure, [7] Deng shiqiang et al. thought that rare earth could decrease the density of C, N, O on the grain boundaries, [8] whereas
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