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Tytuł:
Effect of microwave power on EPR spectra of thermally sterilized eucerinum anhydricum
Autorzy:
Ramos, P.
Pepliński, P.
Pilawa, B.
Powiązania:
https://bibliotekanauki.pl/articles/148715.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
EPR
microwave saturation
free radicals
eucerinum anhydricum
thermal sterilization
Opis:
Free radicals formed during thermal sterilization of eucerinum anhydricum – the pharmaceutical base were examined by an X-band (9.3 GHz) spectrometer. Eucerinum anhydricum was sterilized at different physical conditions according to the Polish Pharmacopeia norms. The samples were heated at temperatures: 160°C (120 min), 170°C (60 min), and 180°C (30 min). The aim of this study is to compare free radical concentration and effect of microwave power on EPR spectra of eucerinum anhydricum base thermally sterilized at different temperatures and periods of time. The effect of time storage on the free radicals in the heated samples was tested. Free radical concentrations in the sample stored 15 min strongly decreased with the increasing of sterilization temperature, probably as the result of recombination. Storage caused strong decrease of free radical concentrations in the samples, probably as the result of interactions with oxygen. It was observed to be independent of sterilization conditions from 2 days of storage and longer. Because of the lowest free radical concentration, for eucerinum anhydricum thermal sterilization at 180°C for 30 min is recommended. The sterilized samples should be stored at inert atmosphere without oxygen molecules. Fast spin-lattice relaxation processes existed in sterilized eucerinum anhydricum. The character of changes of amplitudes and linewidths of EPR lines with increasing of microwave power was the same for different storage times. The parameters of thermal sterilization and storage time influenced free radical concentration in eucerinum anhydricum, but magnetic spin-lattice interactions were unchanged. The usefulness of EPR spectroscopy in optimization of thermal sterilization process of eucerinum anhydricum was confirmed.
Źródło:
Nukleonika; 2015, 60, No. 3, part 1; 439-442
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of aerosol concentration and multivariate processing on the indication of radon progeny concentration in air
Autorzy:
Machaj, B.
Urbański, P.
Powiązania:
https://bibliotekanauki.pl/articles/147261.pdf
Data publikacji:
2004
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
radon progeny
measurement
data processing
Opis:
Measurements of radon progeny concentration in air by a radon progeny monitor are sensitive to the concentration of particles suspended in air. Minimum detectable concentration and accuracy of the measurement are determined by random errors of the monitor. Multivariate data processing can be used to decrease these random errors. Influence of aerosol concentration on the measured results of radon progeny concentration in air, by an RGR-30 mining radiometer, operating on the principle of alpha radiation detection from radon progeny deposited on an air filter, were determined in a radon chamber experiment. The air suspended particle concentration and the radon concentration in the radon chamber were controlled and the corresponding radon progeny concentration was measured by the radon progeny monitor. Additionally, count rate from the monitor detector, originating from the alpha activity deposited on the air filter, was measured at intervals of one minute and was then used for the three-interval, and Principal Component Regression (PCR) data processing. It was found that for the aerosol concentration in air from 40 p/cm3 to approximately 9,000 p/cm3 indications of the radon progeny monitor depends considerably on the aerosol concentration. Radon daughter concentration normalized to the radon concentration against aerosol concentration varied from 0.3 to 0.9. In mines, where the aerosol concentration generally is high, this phenomenon has little effect on the indication of the radon progeny monitor. At low aerosols concentration, appropriate correction of radon progeny concentration has to be taken. Comparison of random errors when measured signal of the monitor (count rate against time) was processed employing the three-interval method and PCR data processing shows that PCR ensures a lower random error.
Źródło:
Nukleonika; 2004, 49, 3; 123-129
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR examination of free radicals thermally formed in vaselinum flavum
Autorzy:
Ramos, P.
Pilawa, B.
Powiązania:
https://bibliotekanauki.pl/articles/148032.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
vaselinum flavum
thermal sterilization
free radicals
EPR spectroscopy
Opis:
The popular pharmaceutical base used in pharmacy – vaselinum flavum – was studied by an X-band (9.3 GHz) EPR spectrometer in the range of microwave power of 2.2–70 mW. The samples were sterilized in hot air oven at temperatures: 160°C (120 min), 170°C (60 min), and 180°C (30 min). The aim of this work was to determine properties and free radical concentrations in vaselinum flavum thermally sterilized at different conditions. The changes in free radical system in vaselinum flavum during storage were analyzed. Free radicals were found in all the heated samples. The lowest free radical concentration was obtained for vaselinum flavum heated at 180°C for 30 min; so these parameters are proposed for the thermal sterilization of this pharmaceutical base. Interactions with oxygen decreased free radical concentration in vaselinum flavum during storage. Strong quenching of free radicals in vaselinum flavum was observed after 2 days for the samples sterilized at temperatures 160 and 180°C. Such an effect for vaselinum flavum heated at temperature 170°C was observed later, 13 days after sterilization. Fast spin-lattice relaxation processes exist in thermally sterilized vaselinum flavum. The EPR lines of heated vaselinum flavum were homogeneously broadened. EPR spectroscopy and its use for examining the thermal sterilization process in pharmacy was confirmed.
Źródło:
Nukleonika; 2015, 60, No. 3, part 1; 443-447
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Principal component data processing in radon metrology
Autorzy:
Machaj, B.
Urbański, P.
Powiązania:
https://bibliotekanauki.pl/articles/147140.pdf
Data publikacji:
2002
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
principal component regression (PCR)
radon daughters measurement
radon measurement
Opis:
A gauge for the measurement of radon and radon daughters concentration was tested in a radon chamber. Count rate distribution in time at the output of radiation detectors was measured and registered. The count rate distribution in time was then processed employing Principal Component Analysis (PCA) and the Root Mean Square Error (RMSE) of the count rate was investigated. It was found that PCA processing removes great part of count rate random fluctuations originating from radiation statistics, which is resulting in a decrease of the count rate random error and in random error of concentration. The RMSE of radon daughters concentration is about 3 times lower when "raw" results are PCA processed. Such decrease of error, without PCA signal processing, would require 9 times higher air flow through the air filter on which the radon daughters are deposited. In case of the measurements of the radon concentration the drop of the error is 2-3 times higher in case of long counting time.
Źródło:
Nukleonika; 2002, 47, 1; 39-42
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of the fraction of paramagnetic centers not-fulfilling the Curie law in coal macerals by the two-temperature EPR measurement method
Autorzy:
Słowik, G. P.
Więckowski, A. B.
Powiązania:
https://bibliotekanauki.pl/articles/146892.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
electron paramagnetic resonance (EPR)
macerals
two-temperature EPR measurement
Opis:
Two-temperature electron paramagnetic resonance (EPR) measurements, applied to determine the relative contributions of paramagnetic centers – fulfilling and not-fulfilling the Curie law, were carried out. The measurements were made on the macerals – exinite and vitrinite, separated from clarain of the Polish medium- -rank coal (85.6 wt% C). The two-temperature EPR measurements, presented in this work, were performed respectively, at temperatures: T1 = 293 K and T2 = 173 K for exinite, and T1 = 293 K and T2 = 153 K for vitrinite. The relative contributions X of spins not-fulfilling the Curie law present in the studied macerals were calculated. A comparison of different methods of calculating the relative contributions of paramagnetic centers – fulfilling and not-fulfilling the Curie law, present in exinite and vitrinite studied by EPR was made.
Źródło:
Nukleonika; 2015, 60, No. 3, part 1; 389-393
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR studies of free radicals in thermally sterilized famotidine
Autorzy:
Ramos, P.
Pilawa, B.
Stroka, E.
Powiązania:
https://bibliotekanauki.pl/articles/148414.pdf
Data publikacji:
2013
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
free radicals
thermal sterilization
famotidine
electron paramagnetic resonance (EPR) spectroscopy
Opis:
Free radicals formation in thermally sterilized famotidine was studied by the use of an X-band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy. The influence of temperature and time of sterilization on free radicals generated in famotidine was determined. The best sterilization conditions for the tested drug were found. Sterilization was done according to the pharmaceutical norms at temperatures 160°C (120 min), 170°C (60 min), and 180°C (30 min). It was pointed out that the optimal temperature of thermal sterilization for famotidine was 170°C and time of heating 60 min in this conditions the lowest free radicals concentration was found. The highest free radicals concentration was measured in famotidine heated at 160°C during 120 min, the long time of sterilization is responsible for this effect. Free radicals concentration changes during storage of famotidine after thermal sterilization. Its value increased with storage time for the drug sterilized at both temperatures of 170°C and 180°C. Free radicals concentration decreases from 7 days after sterilization. Complex system of free radicals with the shape of EPR lines, dependent on microwave power exist in thermally sterilized famotidine. Slow spin-lattice relaxation processes, strong dipolar interactions characterize thermally sterilized famotidine. Microwave saturation indicates that EPR lines of famotidine are homogeneously broadened. The usefulness of EPR spectroscopy to examine of the sterilized drugs was evaluated.
Źródło:
Nukleonika; 2013, 58, 3; 413-418
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A gauge for measuring the dose rate and activity of ophthalmic applicators
Autorzy:
Machaj, B.
Awistowski, E.
Do, H.
Bilski, P.
Olko, P.
Powiązania:
https://bibliotekanauki.pl/articles/147042.pdf
Data publikacji:
2002
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
dose rate
measurements
106Ru ophthalmic applicators
Opis:
A gauge was developed for determining the dose rate distribution and surface activity of ophthalmic brachytherapy applicators, particularly for 106Ru applicators. A plastic fi 2×2 mm scintillator is used as the radiation detector, featuring a high pulse count rate, which results in a low 0.5% random error, due to good counting statistics. Automatic gain control of the photomultiplier tube (PMT) is achieved using a LED as the reference light source. The PMT operates in pulse mode. Long term gain variation due to fatigue of the PMT or ambient temperature variation is thus compensated for. The count rate error due to inaccurate setting of the high voltage supply of the PMT is 0.4%, and the instability error over 7 hours of continuous operation does not exceed 1-2%, peak-to-peak.
Źródło:
Nukleonika; 2002, 47, 3; 107-111
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurement of radon (222Rn) and thoron (220Rn) concentration with a single scintillation cell
Autorzy:
Machaj, B.
Urbański, P.
Bartak, J.
Powiązania:
https://bibliotekanauki.pl/articles/146829.pdf
Data publikacji:
2007
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
radon
thoron
measurement
scintillation cell
Opis:
. A single scintillation cell (ö 54 × 74 mm) is used for the measurement of radon and thoron. The radon and thoron laden air is filtered and forced to flow at 1 dm3/min through the scintillation cell in the period of 1 10 min. The count number from alpha radiation is registered in the periods of 3 10 min and 20 30 min. Two values of detection and deposition efficiency of alpha radiation are used for radon (at air flow and air at rest in the cell) and for thoron. Measurements of radon laden air and thoron laden air showed good agreement between the reference concentration and the measured concentration, not worse than 1% for radon and not worse than 2% for thoron. Combination of radon + thoron concentration showed also a small interference ("cross talk") not worse than 1%.
Źródło:
Nukleonika; 2007, 52, 4; 167-171
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of microwave power on EPR spectra of natural and synthetic dental biocompatible materials
Autorzy:
Adamczyk, J.
Ramos, P.
Pilawa, B.
Powiązania:
https://bibliotekanauki.pl/articles/147235.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
EPR
microwave saturation
paramagnetic centers
dental biocompatible materials
Opis:
Paramagnetic centers in the two exemplary synthetic and natural dental biocompatible materials applied in implantology were examined by the use of an X-band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy. The EPR spectra were measured in the range of microwave power 2.2–70 mW. The aims of this work were to compare paramagnetic centers concentrations in different dental biocompatible materials and to determine the effect of microwave power on parameters of their EPR spectra. It is the very fi rst and innovatory examination of paramagnetic centers in these materials. It was pointed out that paramagnetic centers existed in both natural (~1018 spin/g) and synthetic (~1019 spin/g) dental biocompatible materials, but the lower free radical concentration characterized the natural sample. Continuous microwave saturation of EPR spectra indicated that faster spin-lattice relaxation processes existed in synthetic dental biocompatible materials than in natural material. Linewidths (ΔBpp) of the EPR spectra of the natural dental material slightly increased for the higher microwave powers. Such effect was not observed for the synthetic material. The broad EPR lines (ΔBpp): 2.4 mT, 3.9 mT, were measured for the natural and synthetic dental materials, respectively. Probably strong dipolar interactions between paramagnetic centers in the studied samples may be responsible for their line broadening. EPR spectroscopy is the useful experimental method in the examination of paramagnetic centers in dental biocompatible materials.
Źródło:
Nukleonika; 2015, 60, No. 3, part 1; 449-453
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of hard processes on momentum correlations
Autorzy:
Paić, G.
Skowroński, P.
Tomašik, B.
Powiązania:
https://bibliotekanauki.pl/articles/147440.pdf
Data publikacji:
2004
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
hard processes
jets
momentum correlations
HBT
LHC
ALICE
Opis:
The effect of hard processes to be encountered in HBT studies at the Large Hadron Collider (LHC) have been studied. A simple simulation has allowed us to generate momentum correlations involving jet particles as well as particles originating from the kinetic freeze-out and to compare them to a simple theoretical model which has been developed. The first results on the effect of hard processes on the correlation function for the case of jet quenching are presented.
Źródło:
Nukleonika; 2004, 49,suppl.2; 89-94
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of Co and V substitution on structural properties of FINEMET-type alloys
Autorzy:
Szumiata, T.
Gawroński, M.
Brzózka, K.
Górka, B.
Sovák, P.
Pavlík, P.
Powiązania:
https://bibliotekanauki.pl/articles/148217.pdf
Data publikacji:
2007
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
magnetic texture
CEMS
polarized radiation
Opis:
The effect of addition of Co and V on the hyperfine parameters of amorphous as well as nanocrystalline Finemet-type alloys has been studied by means of transmission Mössbauer spectrometry. It was stated that these elements infiltrate into crystalline grains in the course of crystallization, what causes alteration in structure. Different evolution of magnetic hyperfine field is reported in both cases and analyzed. In the series of alloys substituted by vanadium, the substantial paramagnetic component attributed to iron-poor regions in the amorphous remainder was found.
Źródło:
Nukleonika; 2007, 52, supl. 1; 21-28
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of LiF : Mg,Cu,P (MCP-N) thermoluminescent detectors (TLD) for experimental verification of radial dose distribution models
Autorzy:
Gieszczyk, W.
Olko, P.
Bilski, P.
Grzanka, L.
Obryk, B.
Horwacik, T.
Powiązania:
https://bibliotekanauki.pl/articles/146734.pdf
Data publikacji:
2012
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
heavy charged particles
LiF:Mg,Cu,P (MCP-N)
radial dose distribution
thermoluminescence
unfolding
Opis:
In track structure theory, the radial distribution of dose, D(r), around an ion track plays a fundamental role in predicting the response of biological systems and physical detectors after a dose (or fluence) of ions. According to the formulations of D(r), the local dose at radial distances below 1 nm can reach values as high as 106 Gy. We propose a new method of verifying experimentally the radial dose distribution around alfa-particle tracks, using LiF:Mg,Cu,P (MCP-N) thermoluminescent detectors (TLD) which are able to measure gamma-ray doses in the kGy range via evaluation of their high-temperature TL glow peak structure over the temperature range of 350–550 centigrade. MCP-N detectors were irradiated with Am-241 alfa-particles at fluences ranging from 107 to 1011 particles/cm2, and by Co-60 gamma-ray doses ranging from several Gy up to the MGy. A number N of individual high-temperature TL peaks were analysed in the obtained glow curves by deconvolution, using the GlowFit code. For each of these peaks, an equation relating the intensity, A, of the TL signal obtained after alfa-particle irradiation and after gamma-ray doses, via the dose-frequency function, f alfa(D), was written in the form: A i alfa = integral A i gamma(D)x f alfa (D)dD, i 1,.., N. Using this set of N equations, where A alfa i and A gamma i(D) were known (measured), the single unknown function f alfa(D) was unfolded and converted to D(r). Parametric unfolding and the SAND-II iterative code were applied. While we were able to confirm the 1/r2 dependence of D(r) in agreement with D(r) expressions, we were unable to conclusively evaluate the dependence of D(r) at intermediate ranges of radial distance r. This preliminary result of our unique experimental approach to determine the radial dose distribution around the path of heavy charged particles in LiF detectors, requires further development.
Źródło:
Nukleonika; 2012, 57, 4; 507-512
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
X-ray diffraction, Mössbauer spectroscopy, and magnetoelectric effect studies of (BiFeO3)x-(BaTiO3)1-x solid solutions
Autorzy:
Kowal, K.
Jartych, E.
Guzdek, P.
Stoch, P.
Wodecka-Duś, B.
Lisińska-Czekaj, A.
Czekaj, D.
Powiązania:
https://bibliotekanauki.pl/articles/147352.pdf
Data publikacji:
2013
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
multiferroics
hyperfine interactions
Mössbauer spectroscopy
magnetoelectric effect
Opis:
In this work the hyperfine interactions in (BiFeO3)x-(BaTiO3)1-x solid solutions with relation to their structural properties have been investigated. X-ray diffraction, Mössbauer spectroscopy and magnetoelectric effect measurements have been used for studies of sintered (BiFeO3)x-(BaTiO3)1-x solid solutions with x = 0.9, 0.8 and 0.7. With increasing contents of BaTiO3, the structural transformation from rhombohedral to cubic was observed. The weakening of the hyperfine magnetic fields accompanied by this transformation. On the other hand, the increasing amount of BaTiO3 caused an increase of the magnetoelectric effect.
Źródło:
Nukleonika; 2013, 58, 1; 57-61
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A study of the photoneutron dose equivalent resulting from a Saturne 20 medical linac using Monte Carlo method
Autorzy:
Hashemi, F.
Hashemi-Malayeri, B.
Raisali, G.
Shokrani, P.
Sharafi, A.
Powiązania:
https://bibliotekanauki.pl/articles/148191.pdf
Data publikacji:
2007
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
photoneutron
linac
Monte Carlo method
MCNP4C
dose equivalent
Opis:
High energy linacs have several advantages including lower skin dose and higher dose rate at deep sighted tumors. But, at higher energies photonuclear reactions produce neutron contamination. Photoneutron contamination has been investigated from the early days of modern linacs. However, more studies have become possible using Monte Carlo codes developed in recent years. The aim of this study was to investigate the photoneutron spectrum and dose equivalent produced by an 18 MV Saturne linac at different points of a treatment room and its maze. The MCNP4C code was used to simulate the transport of photoneutrons produced by a typical 18 MV Saturne linac. The treatment room of a radiotherapy facility in which a Saturne 20 linac is installed was modeled. Neutron dose equivalent was calculated and its variations at various distances from the center of the X-ray beam was studied. It was noted that by increasing the distance from the center of the beam, fast neutrons decrease rapidly, but thermal neutrons do not change significantly. In addition, the photoneutron dose equivalent was lower for smaller fields. The fast photoneutrons were not recorded in the maze. It can be concluded that the fast photoneutrons are highly attenuated by concrete barrier, while the slow photoneutrons are increased. In addition, increasing the X-ray field size increases the photoneutron dose equivalent around the treatment room and maze. It seems that the walls play an effective role in increasing the photoneutron dose equivalent.
Źródło:
Nukleonika; 2007, 52, 1; 39-43
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The MAS NMR study of solid solutions based on the YAG crystal
Autorzy:
Padlyak, B. V.
Sergeev, N. A.
Olszewski, M.
Stępień, P.
Powiązania:
https://bibliotekanauki.pl/articles/971533.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
27Al MAS NMR
local structure
solid solutions
yttrium-aluminum garnet (YAG)
Opis:
An 27Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) study of nominally pure and Cr-doped yttrium-aluminum garnet (Y3Al5O12 and Y3Al5O12:Cr) crystals is reported. It has been shown that the doping by Cr of the Y3Al5O12 crystals leads to the variation of the occupation by Al atoms both octahedrally and tetrahedrally coordinated sites of the garnet lattice.
Źródło:
Nukleonika; 2015, 60, No. 3, part 1; 417-421
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł

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