Physical properties of surfactant bilayer membranes: thermal transitions, elasticity, rigidity, cohesion and colloidal interactions

1987 ◽  
Vol 91 (16) ◽  
pp. 4219-4228 ◽  
Author(s):  
Evan. Evans ◽  
David. Needham
Keyword(s):  
Physical Properties ◽  
Thermal Transitions ◽  
Bilayer Membranes ◽  
Colloidal Interactions

Physical properties and surface interactions of bilayer membranes containing N-methylated phosphatidylethanolamines

Biochemistry ◽  
1985 ◽  
Vol 24 (16) ◽  
pp. 4400-4408 ◽  
Author(s):  
Jeannine Gagne ◽  
Leonidas Stamatatos ◽  
Thomas Diacovo ◽  
Sek Wen Hui ◽  
Philip L. Yeagle ◽  
...  
Keyword(s):  
Physical Properties ◽  
Surface Interactions ◽  
Bilayer Membranes

scholarly journals Preliminary Studies of Chemical and Physical Properties of Two Varieties of Avocado Seeds Grown in Chile

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Marcos Flores ◽  
Jaime Ortiz-Viedma ◽  
Ayelen Curaqueo ◽  
Alicia Rodriguez ◽  
Gretel Dovale-Rosabal ◽  
...  
Keyword(s):  
Physical Properties ◽  
Fast Food ◽  
Antiradical Activity ◽  
Color Change ◽  
Ethanol Extract ◽  
Nutritional Composition ◽  
Mechanical Resistance ◽  
Thermal Transitions ◽  
Avocado Oil ◽  
Cut Resistance

In Chile, the most cultivated avocado varieties are Hass and Negra de la Cruz. The increase in the production of fast food preparations, salads, and avocado oil has generated large amounts of seeds and husks as waste, which may constitute a possible new source of bioactive compounds, of great interest to the food and pharmaceutical industry. Therefore, the objective of this study was to determine different nutritional, biochemical, antimicrobial, and physical properties of the SH and SNC seeds grown in Chile. In SH and SNC, their nutritional composition, lipophilic components, and total phenols (PTs) were determined. The antioxidant and antibacterial activity of extracts were measured in different solvent combinations. In addition, the color change of seeds (ΔE) during the browning, the mechanical resistance to the cut, and their thermal transitions by differential calorimetry (DSC) were determined. The results indicated that SH has a higher protein content and lipophilic components. In the ethanol extract, SNC showed greater antiradical activity and is an inhibitor of Gram (+) bacteria. The SNC browning given by ΔE was greater and adjusted well to kinetic and enzymatic models. The physical analyses of the seeds indicated that SNC presented higher cut resistance and lower transition temperature (Tg) with a lower thermal fusion of its lipids, which would be due to its higher unsaturated composition. These properties of SH and SNC can be useful for the agrifood, pharmaceutical, and chemical industries.

Physical properties of bilayer membranes formed from a synthetic saturated phospholipid in n-decane

1971 ◽  
Vol 233 (1) ◽  
pp. 1-6 ◽  
Author(s):  
W.R. Redwood ◽  
F.R. Pfeiffer ◽  
J.A. Weisbach ◽  
T.E. Thompson
Keyword(s):  
Physical Properties ◽  
Bilayer Membranes

scholarly journals Membrane solubility of chlorpromazine. Hygroscopic desorption and centrifugation methods yield comparable results

1984 ◽  
Vol 224 (3) ◽  
pp. 1023-1026 ◽  
Author(s):  
M Luxnat ◽  
H J Müller ◽  
H J Galla
Keyword(s):  
Partition Coefficient ◽  
Physical Properties ◽  
Partition Coefficients ◽  
Biological Membranes ◽  
Membrane Composition ◽  
Bilayer Membranes ◽  
Filtration Method ◽  
Centrifugation Method ◽  
Positively Charged

Binding of the positively charged drug chlorpromazine to artificial and erythrocyte bilayer membranes was investigated by the filtration method called hygroscopic desorption [Conrad & Singer (1979) Proc. Natl. Acad. Sci. U.S.A. 76, 5202-5206] and by the conventional centrifugation method. Only minor differences in the partition coefficients were observed using the two methods. Our finding is not consistent with the observation of Conrad & Singer that amphipaths are completely excluded from biological membranes. However, the partition coefficient is dependent on membrane composition, which means dependent on the physical properties of a membrane.

scholarly journals Physical properties of lipid bilayer membranes: relevance to membrane biological functions.

2000 ◽  
Vol 47 (3) ◽  
pp. 613-625 ◽  
Author(s):  
W K Subczynski ◽  
A Wisniewska
Keyword(s):  
Physical Properties ◽  
Lipid Bilayer ◽  
Plasma Membranes ◽  
Translational Motion ◽  
Biological Membranes ◽  
Fluid Phase ◽  
Spin Labeling ◽  
Lipid Bilayer Membranes ◽  
Bilayer Membranes ◽  
Labeling Method

Over the last 25 years one of us (WKS) has been investigating physical properties of lipid bilayer membranes. In 1991 a group led by WKS was organized into the Laboratory of Structure and Dynamics of Biological Membranes, the effective member of which is AW. Using mainly the electron paramagnetic resonance (EPR) spin-labeling method, we obtained unexpected results, which are significant for the better understanding of the functioning of biological membranes. We have developed a new pulse EPR spin-labeling method for the detection of membrane domains and evaluation of lipid exchange rates. This review will be focused on our main results which can be summarized as follows: (1) Unsaturation of alkyl chains greatly reduces the ordering and rigidifying effects of cholesterol although the unsaturation alone gives only minor fluidizing effects, as observed by order and reorientational motion, and rather significant rigidifying effects, as observed by translational motion of probe molecules; (2) Fluid-phase model membranes and cell plasma membranes are not barriers to oxygen and nitric oxide transport; (3) Polar carotenoids can regulate membrane fluidity in a way similar to cholesterol; (4) Formation of effective hydrophobic barriers to the permeation of small polar molecules across membranes requires alkyl chain unsaturation and/or the presence of cholesterol; (5) Fluid-phase micro-immiscibility takes place in cis-unsaturated phosphatidylcholine-cholesterol membranes and induces the formation of cholesterol-rich domains; (6) In membranes containing high concentrations of transmembrane proteins a new lipid domain is formed, with lipids trapped within aggregates of proteins, in which the lipid dynamics is diminished to the level of gel-phase.

The Photometric Properties of the Ap Stars

1976 ◽  
Vol 32 ◽  
pp. 365-377 ◽  
Author(s):  
B. Hauck
Keyword(s):  
Physical Properties ◽  
Ap Stars

The Ap stars are numerous - the photometric systems tool It would be very tedious to review in detail all that which is in the literature concerning the photometry of the Ap stars. In my opinion it is necessary to examine the problem of the photometric properties of the Ap stars by considering first of all the possibility of deriving some physical properties for the Ap stars, or of detecting new ones. My talk today is prepared in this spirit. The classification by means of photoelectric photometric systems is at the present time very well established for many systems, such as UBV, uvbyβ, Vilnius, Geneva and DDO systems. Details and methods of classification can be found in Golay (1974) or in the proceedings of the Albany Colloquium edited by Philip and Hayes (1975).

The Infection of Cells by Bullet-Shaped Viruses

1969 ◽  
Vol 27 ◽  
pp. 372-373
Author(s):  
Frederick A. Murphy ◽  
Alyne K. Harrison ◽  
Sylvia G. Whitfield
Keyword(s):  
Electron Microscopy ◽  
Physical Properties ◽  
Host Cell ◽  
Thin Section ◽  
Cultured Cells ◽  
Cell Infection ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Section Electron Microscopy

The bullet-shaped viruses are currently classified together on the basis of similarities in virion morphology and physical properties. Biologically and ecologically the member viruses are extremely diverse. In searching for further bases for making comparisons of these agents, the nature of host cell infection, both in vivo and in cultured cells, has been explored by thin-section electron microscopy.

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