Search results for "Radiation"
showing 10 items of 5298 documents
Stoichiometric and kinetic study of the 99Tc-DMSA complex obtained with stannous excess: A possible model for the physico-chemical behaviour of the r…
1982
A stoichiometric and kinetic study was made of the 99mTc-DMSA complex obtained in the presence of large amounts of Sn2+. It is demonstrated that the Tc oxidation state is 3+. It is established that the complex degrades to another one if there is an Sn2+ deficiency. These results were confirmed by spectroscopic and spectrophotometric methods.
Über eine bestimmung der energie und intensität komplexer photopeaks
1967
Zusammenfassung Zur Zerlegung komplexer Photopeaks werden einige Methoden beschrieben, deren Energie und Intensitat selbst unter ungunstigen Bedingungen uber eine graphische Auswertung zu bestimmen gestatten. Hierbei erfolgt die Ermittlung der Peaklage (Energie) uber eine graphische Differentiation des reinen bzw. logarithmierten Spektrumsverlaufes. Die zur Bestimmung der Peakintensitat abgeleiteten Verfahren basieren darauf, das alle Photopeaks in einem γ-Spektrum auf einen einzigen Standardpeak zuruckgefuhrt werden konnen, der durch zwei empirische, bezuglich der relativen Peakhole normierte Funktionen exakt beschrieben werden kann. Zur Zerlegung einiger typischer Beispiele einer Peakuber…
Stability of the radiopharmaceutical []DMSA: Study of the ligand exchange reaction with [99Tc]EDTA
1983
Abstract A kinetic study was made of the ligand exchange reaction between [ 99 m Tc]EDTA and DMSA. The results of this study indicate that this exchange reaction is closely related to temperature and pH. Kinetic and thermodynamic parameters demonstrate that both complexes—[ 99 m Tc]EDTA and [ 99 m Tc]DMSA—have a similar stability. Furthermore, the existence of an acid-basic catalysis for the global exchange reaction was established, and the catalytic parameters were calculated. These data were obtained by radiochromatography and visible spectrophotometry.
Gamma rays induced synthesis of graphene oxide/gold nanoparticle composites: structural and photothermal study
2022
Gamma irradiation provides an alternative pathway to conventional gold nanoparticle synthesis because it is simple, fast, and economical. Here, we employed gamma irradiation at low doses (1–20 kGy) to obtain gold nanoparticles (Au NPs) anchored onto graphene oxide (GO) sheets. GO was selected as a suitable platform for the nucleation and growth of Au NPs because of its large surface area and good dispersibility in water due to the presence of polar oxygen-containing functional groups in its structure. Gamma irradiation at all the applied doses led to the reduction of chloroauric acid and the formation of evenly distributed Au NPs at the GO surface, simultaneously causing the reduction of GO…
Neutron-induced defects in optical fibers
2014
We present a study on 0.8 MeV neutron-induced defects up to fluences of 1017 n/cm2 in fluorine doped optical fibers by using electron paramagnetic resonance, optical absorption and confocal micro-luminescence techniques. Our results allow to address the microscopic mechanisms leading to the generation of Silica-related point-defects such as E', H(I), POR and NBOH Centers.
Origin of the visible absorption in radiation-resistant optical fibers
2013
In this work we investigated the point defects at the origin of the degradation of radiation-tolerant optical fibers used in the visible part of the spectrum for plasma diagnostics in radiation environments. For this aim, the effects of γ -ray irradiation up to the dose of 10 MGy(SiO2) and post-irradiation thermal annealing at 550◦C were studied for a Fluorinedoped fiber. An absorption peaking around 2 eV is mainly responsible for the measured radiation-induced losses, its origin being currently debated in the literature. On the basis of the unchanging shape of this band with the radiation dose, its correlation with the 1.9 eV photoluminescent band and the thermal treatment results we assig…
Time-resolved luminescence and absorption in CdWO4
1998
Abstract The luminescence and short-lived absorption are studied in CdWO 4 single crystals under pulsed laser beam as well as pulsed electron beam excitation. The luminescence spectrum and decay kinetics for CdWO 4 powder are studied. The short-lived absorption in single crystals arises from electron transitions from the luminescence center excited state to the conduction band. From luminescence and short-lived absorption spectra the energy depths of luminescence center excited and ground states are estimated.
Thermally and optically stimulated radiative processes in LiBaF3 crystals
2004
Abstract In LiBaF3 crystals both valence–core transitions (5.4– 6.5 eV ) and so-called self-trapped exciton luminescence (about 4.3 eV ) are important for practical application. Here, we present a study of 4.3 eV luminescence under photo- and thermostimulation after X-irradiation of undoped LiBaF3 crystals at various temperatures. Optically stimulated luminescence as a result of electron recombination with both self-trapped holes and holes localized at some defects, were observed after X-irradiation below 130 K and that of electron recombination with defect-localized holes was observed after X-irradiation above 130 K . The spectra of thermo-stimulated luminescence (TSL) contain a broad band…
centers induced by γ irradiation in sol–gel synthesized oxygen deficient amorphous silicon dioxide
2007
The effects of room temperature γ-ray irradiation up to a dose of ∼1300 kGy are investigated by Electron paramagnetic resonance (EPR) measurements in amorphous silicon dioxide (a-SiO2) produced by a sol-gel synthesis method that introduces O{triple bond, long}Si{single bond}Si{triple bond, long}O oxygen deficiency. We have found that exposure to radiation generates the Eγ′ center with the same spectral features found in high purity commercial a-SiO2. The maximum concentration of defects induced in this sol-gel material indicates that its resistance to radiation is comparable to that of synthetic fused a-SiO2. The concentration of Eγ′ center increases with irradiation, featuring a sublinear …
Isolation and characterization of a photosystem I-associated antenna (LHC I) and a photosystem I—core complex from the chlorophyll c-containing alga …
1993
Abstract A photosystem (PS) I holocomplex was isolated from Pleurochloris meiringensis Vischer (Xanthophyceae) using sucrose density centrifugation. This complex exhibited a fluorescence emission maximum at 715 nm, which is in accordance with the long wavelength emission of whole cells. The complex was further dissociated into a core complex and a light-harvesting protein (LHC I). The core protein contains mainly Chl a and β-carotene, is 8.25 times enriched in P700 and has its main emission maximum at 715 nm. Therefore, the longest wavelength emission of P. meiringensis is due to the PS I core, which is in contrast to higher plants. The LHC I differs from LHC II with regard to its polypepti…