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The Effect of Mild Rehydration on Freeze-Dried Dipalmitoylphosphatidylcholine (DPPC) Multilamellar Membranes as Observed by Proton NMR and Sorption Isotherm

100%

Harańczyk H., Leja A., Nowak P., Baran E., Strzałka K.

Acta Physica Polonica A

2016

vol. 129

issue 2

179-184

Between neighbouring bilayers of lyophilized dipalmitoylphosphatidylcholine (DPPC) multilamellar vesicles the total number of water molecules equals 9 H₂O molecules/1 DPPC molecule. One of these molecules is very tightly bound to the lipid molecule, seven are in immobilized (tightly bound) water fraction whereas the last one belongs to mobile water fraction. The rehydration from the gaseous phase of the DPPC model membranes was investigated using hydration kinetics, sorption isotherm, and high power proton relaxometry. The obtained data for DPPC were compared with these obtained for wheat photosynthetic membranes. Rehydrated photosynthetic membranes differ from DPPC model membranes in hydration kinetics. The average hydration time has a similar value: (22.0 ± 2.8) h (photosynthetic membrane) and (19.8 ± 1.6) h (DPPC), however hydration kinetics was described by one-exponential function for photosynthetic membrane, while for model membrane it shows fine double exponential form. The sigmoidal form of sorption isotherm is better fitted using Dent model than by the Brunauer-Emmett-Teller formula. The Brunauer-Emmett-Teller/Dent deviation parameter b =0.93 either for photosynthetic or for model membranes. The mass of water saturating primary water binding sites equals ΔM/m₀= 0.017 (wheat photosynthetic membranes) and 0.027 (DPPC). The detected by NMR-isotherm study mass of water "sealed" in model membrane structures was about ΔMₛ/m₀=0.182 (about 7-8 H₂O molecules/1 DPPC molecule), and ΔMₛ/m₀= 0.066 for photosynthetic membrane.

Low Temperature Processing of Nanostructures Based on II-VI Semiconductors Quantum Wells

86%

Majewicz M., Śnieżek D., Wojciechowski T., Baran E., Nowicki P., Wojtowicz T., Wróbel J.

Acta Physica Polonica A

2014

vol. 126

issue 5

1174-1176

We report the first results of electron beam lithography processes performed on polymethyl methacrylate (PMMA) and hydrogen silsesquioxane (HSQ) resists, which have been pre-backed in vacuum at T ≤ 90°C. For such low temperature processing the lithographical resolution is reduced as compared to standard procedures, however, the exposure contrast and adhesion to CdTe and HgTe substrates have been sufficient for the fabrication of sub-μ m quantum devices. Furthermore, the new method of electrical microcontact forming is proposed, based on the local melting and annealing of an indium metal layer, performed with the application of accelerated electron beam. The method has been tested for CdTe/CdMgTe quantum wells using the lithography techniques, the exposure parameters have been optimized by inspecting the morphology of annealed metal film via the in situ imaging.

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2 Acta Physica Polonica A

1 2016

1 2014

2 Baran E.

1 Harańczyk H.

1 Leja A.

1 Majewicz M.

1 Nowak P.

1 Nowicki P.

1 Strzałka K.

1 Wojciechowski T.

1 Wojtowicz T.

1 Wróbel J.

1 Śnieżek D.

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The Effect of Mild Rehydration on Freeze-Dried Dipalmitoylphosphatidylcholine (DPPC) Multilamellar Membranes as Observed by Proton NMR and Sorption Isotherm

Low Temperature Processing of Nanostructures Based on II-VI Semiconductors Quantum Wells