Effect of cholesterol on the dipole potential of lipid membranes

The membrane dipole potential, ψd, is an electrical potential difference with a value typically in the range 150 – 350 mV (positive in the membrane interior) which is located in the lipid headgroup region of the membrane, between the linkage of the hydrocarbon chains to the phospholipid glycerol backbone and the adjacent aqueous solution. At its physiological level in animal plasma membranes (up to 50 mol%), cholesterol makes a significant contribution to ψd of approximately 65 mV; the rest arising from other lipid components of the membrane, in particular phospholipids. Via its effect on ψd, cholesterol may modulate the activity of membrane proteins. This could occur through preferential stabilization of protein conformational states. Based on its effect on ψd, cholesterol would be expected to favour protein conformations associated with a small local hydrophobic membrane thickness. Via its membrane condensing effect, which also produces an increase in ψd, cholesterol could further modulate interactions of polybasic cytoplasmic extensions of membrane proteins, in particular P-type ATPases, with anionic lipid headgroups on the membrane surface, thus leading to enhanced conformational stabilization effects and changes to ion pumping activity.Australian Research Counci

Study of influence parameters application layers TiO2 by ALD method on their adhesion to the mettalic substrate

W niniejszej pracy badano wpływ parametrów nanoszenia warstw TiO2 metodą ALD na ich adhezję do metalicznego podłoża. Warstwa TiO2została naniesiona na próbki wykonane ze stali nierdzewnej 316 LVM polerowane elektrochemicznie oraz mechanicznie. Warstwy nanoszono z wykorzystaniem różnych zespołów parametrów nanoszenia, jakimi były zmienna ilość cykli nanoszenia oraz zmienna temperatura procesu. W celu badania adhezji naniesionych warstw do podłoża wykorzystano metodę scratch test. Podsumowując, badania wykazały, że najkorzystniejszym zespołem własności mechanicznych charakteryzowały się warstwy TiO2naniesione na stal 316 LVM metodą ALD w temperaturze 300°C w czasie 500 cykli.In this study have been investigated influence of parameters applying layers of TiO2by ALD method on their adhesion to the metal substrate. TiO2 layers was applied on the samples made of stainless steel 316 LVM polished electrochemically and mechanically. To deposition layers was using different combination of parameters, which as first were a variable number of cycles of application and variable temperature of process. Next was tested adhesion to the substrate by use of scratch test. The results of studies shown that the best values of mechanical properties characterized samples with layer of TiO2 deposited on stainless steel by ALD method at temperature 300°C with 500 cycles