Free Volume Determination of Azobenzene−PMMA Copolymer by a Pulsed Low-Energy Positron Lifetime Beam with in-Situ UV Illumination

2004 ◽  
Vol 37 (21) ◽  
pp. 8035-8042 ◽  
Author(s):  
John Algers ◽  
Peter Sperr ◽  
Werner Egger ◽  
Laszlo Liszkay ◽  
Gottfried Kögel ◽  
...  
Keyword(s):  
Free Volume ◽  
Positron Lifetime ◽  
Low Energy ◽  
Volume Determination ◽  
Uv Illumination

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.

Free Volume and Density Gradients of Amorphous Polymer Surfaces As Determined by Use of a Pulsed Low-Energy Positron Lifetime Beam and PVT Data

2004 ◽  
Vol 37 (11) ◽  
pp. 4201-4210 ◽  
Author(s):  
John Algers ◽  
Ryoichi Suzuki ◽  
Toshiyuki Ohdaira ◽  
Frans H. J. Maurer
Keyword(s):  
Free Volume ◽  
Positron Lifetime ◽  
Amorphous Polymer ◽  
Low Energy ◽  
Polymer Surfaces ◽  
Density Gradients ◽  
Pvt Data

Effect of Water on the Size Distribution of Free-Volume Holes in Nafion Membrane

2012 ◽  
Vol 733 ◽  
pp. 49-52 ◽  
Author(s):  
Jakub Čížek ◽  
Zuzana Barnovská ◽  
Michal Šourek ◽  
Ivan Procházka
Keyword(s):  
Size Distribution ◽  
Free Volume ◽  
Water Uptake ◽  
Positron Lifetime ◽  
Ionic Clusters ◽  
Mean Size ◽  
Positron Lifetime Spectroscopy ◽  
The Mean ◽  
Kinetics Of

Positron lifetime spectroscopy was employed for investigation of the size distribution of free volume holes in Nafion N-1110 membrane. Size distribution of free volume holes was determined in the as-received and dried membrane and in the membrane immersed in water at various temperatures. It was found that absorbed water causes reduction of the mean size of free volume holes and increase of their dispersion and concentration. This indicates that free volumes are split by swollen ionic clusters absorbing water. The kinetics of water uptake and the amount of absorbed solvent was determined by in-situ measurement of the weight increase.

Characterization of free volume and density gradients of polystyrene surfaces by low-energy positron lifetime measurements

Polymer ◽  
2004 ◽  
Vol 45 (13) ◽  
pp. 4533-4539 ◽  
Author(s):  
John Algers ◽  
Ryoichi Suzuki ◽  
Toshiyuki Ohdaira ◽  
Frans H.J. Maurer
Keyword(s):  
Free Volume ◽  
Positron Lifetime ◽  
Low Energy ◽  
Density Gradients ◽  
Lifetime Measurements

scholarly journals Study of interfaces in polymer-metal oxide films and free-volume hole using low-energy positron lifetime measurements

2019 ◽  
Vol 4 (3) ◽  
pp. 413-419 ◽  
Author(s):  
Aman Deep Acharya ◽  
Bhawna Sarwan ◽  
Ratnesh Sharma ◽  
S.B. Shrivastava ◽  
Manoj Kumar Rathore
Keyword(s):  
Metal Oxide ◽  
Free Volume ◽  
Positron Lifetime ◽  
Oxide Films ◽  
Low Energy ◽  
Metal Oxide Films ◽  
Lifetime Measurements ◽  
Polymer Metal ◽  
Free Volume Hole

scholarly journals Principles of positron porosimetry

Nukleonika ◽  
2015 ◽  
Vol 60 (4) ◽  
pp. 795-800 ◽  
Author(s):  
Radosław Zaleski
Keyword(s):  
Numerical Analysis ◽  
Pore Size ◽  
Pore Volume ◽  
Unique Feature ◽  
Positron Lifetime ◽  
Review Article ◽  
Empirical Parameter ◽  
Positron Annihilation Lifetime

Abstract The paper deals with positron porosimetry (PP), which is based on positron annihilation lifetime spectroscopy (PALS). The numerical analysis of positron lifetime spectra for PP is more demanding than in most of other applications of PALS. The resulting intensity distributions of ortho-positronium (o-Ps) lifetimes are interpreted in terms of the extended Tao-Eldrup (ETE) model, which provides the dependence between the o-Ps lifetime and pore size. Additionally, the relation between the intensity of an o-Ps component and the pore volume allows obtaining pore size distribution (PSD). The value of the empirical parameter Δ, which is dependent on material, can be estimated from the temperature dependence of an o-Ps lifetime. The most unique feature of PP among other techniques that allow determination of PSDs is its ability to perform measurements in almost any conditions. This makes this method suitable for various in situ studies. In this review article, both the capabilities and the limitations of PP are discussed. The methods to overcome some of the limitations are presented.

INDIREKTE PAPIERCHROMATOGRAPHISCHE METHODE ZUR BESTIMMUNG DER HARNOESTROGENE

1961 ◽  
Vol 38 (4) ◽  
pp. 545-562 ◽  
Author(s):  
L. Kecskés ◽  
F. Mutschler ◽  
I. Glós ◽  
E. Thán ◽  
I. Farkas ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Granulosa Cell ◽  
Iron Content ◽  
List Type ◽  
Granulosa Cell Tumour ◽  
Hydrolysis Of ◽  
Phenol Fraction ◽  
Qualitative Determination

ABSTRACT 1. An indirect paperchromatographic method is described for separating urinary oestrogens; this consists of the following steps: acidic hydrolysis, extraction with ether, dissociation of phenol-fractions with partition between the solvents. Previous purification of phenol fraction with the aid of paperchromatography. The elution of oestrogen containing fractions is followed by acetylation. Oestrogen acetate is isolated by re-chromatography. The chromatogram was developed after hydrolysis of the oestrogens 'in situ' on the paper. The quantity of oestrogens was determined indirectly, by means of an iron-reaction, after the elution of the iron content of the oestrogen spot, which was developed by the Jellinek-reaction. 2. The method described above is satisfactory for determining urinary oestrogen, 17β-oestradiol and oestriol, but could include 16-epioestriol and other oestrogenic metabolites. 3. The sensitivity of the method is 1.3–1.6 μg/24 hours. 4. The quantitative and qualitative determination of urinary oestrogens with the above mentioned method was performed in 50 pregnant and 9 non pregnant women, and also in 2 patients with granulosa cell tumour.

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