Wyniki wyszukiwania - Biblioteka Nauki

1

PALS investigation of resorcinol under high pressure

100%

Tydda M. , Jasińska B. , Pieniążek A.

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2013

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tom Vol. 58, No. 1

195-198

EN

Two kinds of measurements were conducted with resorcinol at high pressure : the first one with the use of a mechanical press and the second one with the use of a gaseous compressor. In the second case, due to some gas penetrating the material structure, the lifetime spectra obtained were difficult to analyze. The free volumes in resorcinol were influenced both by high pressure and the gas coming into the crystallographic structure.

2

Positrons in naphthalene : critical remarks on the relation between o-Ps lifetime and void size

100%

Goworek T. , Zgardzińska B. , Wawryszczuk J.

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2013

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tom Vol. 58, No. 1

183-187

EN

Lowering the temperature or applying high pressure leads to elimination of positronium component in the e+ lifetime spectrum in solid naphthalene. Disappearance of positronium means reaching the free volume size limit at which there is no energy level in the potential well. It allows to estimate that size, which is found inconsistent with predictions of the popular Tao-Eldrup model. The range of applicability of that model is discussed. The dependence of the free e+ decay constant on pressure indicates that positronium is formed not only in the blob processes, but during the whole free positron life. The lifetime of free positrons begins to rise with temperature earlier than Ps intensity.

3

Acoustic and Volu,E Effects Of Self-Association Of 3-Methylpyrazole In Cyclohexane

75%

Bebek K. , Filosek G. , Ernst S.

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tom Vol. 25

23-28

EN

The speeds of ultrasound in and densities of 3-methylopyrazole with cyclohexane mixtures were measured in the whole concetration range at 293.15 and 313.15 K. The Excess molar volumes, free volumes excess volumes and diabatic copressibilty coefficients, as well as the free intermolecular lenghts were determinated for the binaries. The dependance of the excess molar volumes and excess free volumes on the mixture composition were compared and discussed in terms of the free intermolecular lenght and other factors affecting the self-association of 3-methylopyrazole and structural changes of the non-polar solvent. Search Site

4

Ultrasonic and Volumetric Effects of Self-Association of Aliphatic Alcohols in Cyclohexane

75%

Bebek K.

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2003

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tom Vol. 24

17-22

EN

The speed of ulrtasound in and densities of binary solutions of ethanol, propan-2-ol and 2-methylopropan-2-ol in cyclohexane were measured on the whole concentration range at 293.15K. The excess molar volumes, free volumies, excess free volumes and adiabatic cmpressibility coeffcients, as well as the free intermolecular lenghts were determined for binaries. The dependance of the excess molar volumes and excess free volumes on the mixture composition were compared and discussed in terms of the intermolecular lenght and other factors afecting the self-association of alcohols and structural changes od the solvent.

5

Influence of the free volume and chain flexibility on transport properties of membranes

63%

Danch A. , Osoba W.

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2002

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tom z. 47

19-28

EN

The results of positron annihilation lifetime spectroscopy, calorimetric measurements and mechanical spectroscopy are presented for the chosen membranes. The concept of the two amorphous fractions in the semicrystalline system is applied, as the first attempt, in order to better explain the transport phenomenon. New formula, for the relaxation time evaluation (tau), is proposed. Some correlation between the transport parameters and the tau values was found.

PL

Przedstawiono wyniki badań objętości swobodnych metodą anihilacji pozytonów oraz ruchliwości segmentów łańcucha polimerowego w wybranych membranach. W celu wyjaśnienia transportu, dla procesu dyfuzji przez membranę substancji lotnych, poddaje się pod dyskusję możliwość zastosowania koncepcji zakładającej istnienie dwóch obszarów amorficznych. Zaproponowanie nowego równania dla czasu relaksacji (tau) pozwoliło określić korelację pomiędzy parametrami transportowymi, a strukturą nadcząsteczkową membrany.

6

Analiza porównawcza struktury wewnętrznej implantów hydrofilowych oraz hydrofobowych stosowanych w chirurgii okulistycznej metodą spektroskopii czasów życia pozytonów

51%

Chamerski K.

Technical Issues

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2015

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tom nr 3

3--10

EN

In presented work internal structures of intraocular lenses were analyzed in terms of defectiveness degree. Studies were conducted by means of positron annihilation lifetime spectroscopy method PALS. The aim of the work was determination of basic parameters describing annihilation centers in research materials, such as positron lifetime in bulk material, mean positron lifetime in the internal structure, positron trapping rate by trapping centers as well as free volumes dimensions. In obtained results differences in free volumes and positron traps concentrations between hydrophilic and hydrophobic materials were noted. Furthermore, comparison of materials with and without blue light chromophores revealed differences in positron trapping rate by multivacancy-like free spaces. Achieved results were referenced for mechanical properties of the studied materials.