Positron Annihilation Lifetime Spectroscopy (PALS) for Interdiffusion Studies in Disperse Blends of Compatible Polymers:  A Quantitative Analysis

2002 ◽  
Vol 35 (16) ◽  
pp. 6313-6323 ◽  
Author(s):  
G. Dlubek ◽  
J. Pionteck ◽  
V. Bondarenko ◽  
G. Pompe ◽  
Ch. Taesler ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Positron Annihilation ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Positron Annihilation Lifetime

Preliminary Positron Lifetime Results on Free Volumes in Cyclodextrins

2010 ◽  
Vol 666 ◽  
pp. 99-102 ◽  
Author(s):  
Maria Fatima Ferreira Marques ◽  
A.M.G. Moreira Da Silva ◽  
P.M. Gordo ◽  
Z. Kajcsos
Keyword(s):  
Positron Annihilation ◽  
Free Volume ◽  
Positron Lifetime ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Positron Source ◽  
Lifetime Component ◽  
Positron Annihilation Lifetime ◽  
Long Lifetime

Positron annihilation lifetime spectroscopy was used to study the free-volume parameters in various pure -, - and -cyclodextrins samples and, in the case of β-cyclodextrin, with inclusion of S-carvone and thymoquinone. The results clearly indicate the presence of long lifetime components related to Ps-formation. The data show that the addition of S-carvone to β-cyclodextrin results in a decrease of o-Ps lifetime that we ascribe to a reduction of free volume holes from 81.8 to 63.7 Å3. The long lifetime component disappears when thymoquinone is added to -cyclodextrin, indicating this substance acts as an o-Ps quencher. For all samples studied, a decrease in the long lifetime component values was observed with increasing source in situ time, a result that might be attributed to the irradiation of the sample by the 22Na positron source.

Ceramide increases free volume voids in DPPC membranes

RSC Advances ◽  
2015 ◽  
Vol 5 (55) ◽  
pp. 44282-44290 ◽  
Author(s):  
E. Axpe ◽  
A. B. García-Arribas ◽  
J. I. Mujika ◽  
D. Mérida ◽  
A. Alonso ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Free Volume ◽  
Lipid Membranes ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Positron Annihilation Lifetime

We have measured by positron annihilation lifetime spectroscopy (PALS) that ceramide increases the size of the free volume holes in DPPC lipid membranes.

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