Authors:Zs. Kajcsos, L. Liszkay, L. Varga, K. Lázár and L. Lohonyai
Positron annihilation (PA) investigations were performed on zeolites (X, Y and ZSM-5) and on microcrystalline MgO, Al2O3 and SiO2, providing long lifetime components attributed to o-Ps atoms. In addition to the positron lifetime (LT) measurement, the energy distribution (ED) of the annihilation gamma radiation spectrum was recorded in the 30 keV–1.5 MeV range for different samples and was compared to reference distributions for Si and GaAs samples, where no long-living Ps states are formed. Apart from the strong correlation with the water content in the samples, the positron data collected testify much more pronounced positronium hosting features for powders of the mentioned oxides than for zeolites. Positron LT spectroscopy combined with recording of the ED of the annihilation radiation provides reliable information on the formation of long living 3 states.
Authors:G. Duplâtre, Zs. Kajcsos, T. Goworek, L. Varga, L. Liszkay, I. Billard and K. Lázár
Positron annihilatioin data collected for zeosil (a zeoilite-type solid allowing abundant Psformation) are discussed, with particular attention payed to the longest-lived positronium states as observed in lifetime spectroscopy experiments. To unravel the nature of these components, additional information was sought by applying an extermal magnetic field and by reecording the total energy distributioin of the annihilation radiation. From both the lifetime and the extended Doppler spectra, it is shown that positronium presents a very long-lived component with a relative intensity of ca. 30% and a lifetime close to the intrinsic tripler lifetime (140ns), therefore undergoing almost no pick-off annihilation. From the magnetic field experiments, the contact density parameter has a value of essentially 1, which is characteristic of an unpoerturbed triplet Ps state in vacuo. This positronium state therefore does not appear to interact with the medium.
Authors:L. Varga, L. Liszkay, Zs. Kajcsos, K. Lázár, H. Beyer, G. Onestyák, E. Kótai and L. Lohonyai
In many sorts of zeolites long-living positron components are manifested, connected presumably with Ps-formation in various kinds of free space in the zeolite structure. Literature values demonstrate, however, a broad scasttr of data obtained for assumedly on the same composition of zeolite indicating the possible influence of tehnology, adsorbates, impurities, water content, etc. In the present work spectral changes of the 511 keV annihilation peak and its vicinity are evaluated, applying for the first time a combination of theS and W parameters and the 3-specific left plateau region measured in zeolites. To ensure reproducible experimental conditions, evaluated samples were measured. The data show individual temperature behaviours of the annihilation parameters in the studied temperature range of 90–450 K for each kind of samples. The temperature dependence becomes reproducible after the first heating run. The results are discussed with respect to the evolution of long-living positron and positronium components.
Authors:David Tarnoki, A.D. Tarnoki, Zs. Lazar, Cs. Korom, V. Berczi, I. Horvath and K. Karlinger
Genetic effects that contribute to the risk of developing chronic obstructive pulmonary disease (COPD) have been reported. Our purpose was to estimate the possible genetic influence on CT features related to COPD in twins.
Authors:A. Bikov, Zs Lazar, K. Schandl, B. Antus, G. Losonczy and Ildiko Horvath
Exercise-caused metabolic changes can be followed by monitoring exhaled volatiles; however it has not been previously reported if a spectrum of exhaled gases is modified after physical challenge. We have hypothesized that changes in volatile molecules assessed by an electronic nose may be the reason for the alkalization of the exhaled breath condensate (EBC) fluid following physical exercise.Ten healthy young subjects performed a 6-minute running test. Exhaled breath samples pre-exercise and post-exercise (0 min, 15 min, 30 min and 60 min) were collected for volatile pattern (“smellprint”) determination and pH measurements (at 5.33 kPa CO2), respectively. Exhaled breath smellprints were analyzed using principal component analysis and were related to EBC pH.Smellprints (p=0.04) and EBC pH (p=0.01) were altered during exercise challenge. Compared to pre-exercise values, smellprints and pH differed at 15 min, 30 min and 60 min following exercise (p<0.05), while no difference was found at 0 min post-exercise. In addition, a significant correlation was found between volatile pattern of exhaled breath and EBC pH (p=0.01, r=−0.34).Physical exercise changes the pattern of exhaled volatiles together with an increase in pH of breath. Changes in volatiles may be responsible for increase in EBC pH.