Results 1 - 10 of 13596
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[en] One of the methods used to treat different cancer diseases is the employment of therapeutic radioisotopes. Therefore, many clinical, theoretical and experimental studies are being carried out on those radioisotopes. In this study, the effects of level density models and gamma ray strength functions on the theoretical production cross-section calculations for the therapeutic radioisotopes Y, Sm, Er, Lu and Re in the (n,γ) route have been investigated. TALYS 1.9 code has been used by employing different level density models and gamma ray strength functions. The theoretically obtained data were compared with the experimental data taken from the literature. The results are presented graphically for better interpretation.
[en] Highly radioactive Pu-doped and non-radioactive samples of borosilicate glass with chemical compositions and synthesis routine similar to SON68 glass were studied under static saturated leaching conditions in distilled water at 90 °C. Dramatic differences in behavior of the radioactive and model glasses were observed. On time scale of 4 months the radioactive glass is fully covered by mechanically unstable alteration layer, possibly consisting of aluminum hydroxides with small fraction of a separate secondary Pu bearing phase. The model glass remains virtually pristine. Addition of Eu into the glass allowed examination of the glass radio- and photoluminescence and to assess changes or REE impurity local environment during self-irradiation and leaching. Photoluminescence spectra suggest more ordered local environment of europium ions in the alteration "gel" than in the bulk glass. Peculiar behavior of the photoluminescence spectra excited at different laser power is observed for the alteration layer and is ascribed to optical bleaching of color centers.
[en] Polonium is rapidly emerging as an international environmental health concern primarily because of the recent rise in hydraulic fracturing (fracking). Recovery of unconventional oil and gas generates produced water containing natural radioactivity, which is increasing the radiological impact of 210Po. In this context, accurate measurements of 210Po in environmental samples is crucial because 210Po is the main contributor to the natural radiation dose received by all living organisms. However, the analytical chemistry of polonium is complicated, primarily due to its volatility. This review highlights recent analytical progress and challenges in determination of 210Po in the environmental and biological samples. (author)
[en] Complete sets of reaction mechanisms are proposed in the acidic and reductive dissolution of magnetite, nickel ferrite, and chromite using the HyBRID (Hydrazine Based Reductive metal Ion Decontamination) process for the decontamination of a primary coolant system of nuclear power plant. Hydrazine participated in the reaction pathway of reducing ferric ions to ferrous ions and simultaneously regenerating oxidized cupric ions into cuprous ions. The data of the heat capacity, the heat of formation, the entropy of formation, and the Gibbs energy of formation for all chemical species and ions were collected from the HSC Chemistry 9 database. The enthalpy, entropy, and Gibbs energy changes of reactions were calculated in the temperature range of 298.15–373.15 K for individual reactions. The degree of spontaneity decreased with the increase of the temperature. The reaction spontaneity was significantly enhanced by addition of hydrazine and slightly increased by further addition of copper sulfate. (author)
[en] The radioactivity of cesium in the water and sediments of two major rivers was measured along with airborne radioactivity in Namie Town, after the recent partial lift on the evacuation order in 2017. The observed concentrations were up to 384 ± 11 mBq/L for 137Cs in unfiltered water and 1.28 ± 0.09 mBq m-3 for 137Cs in air, while the sediment had a maximum of 44,900 ± 23 Bq kg-1 for 137Cs. The potential yearly committed effective dose was estimated based on the data. (author)
[en] The main structure of polystyrene-divinylbenzene (PSD) was synthesized by suspension method, and chlorinated resin (PSD-Cl) obtained by chloromethylation,then an alkylimide was grafted onto the resin skeleton to obtain the new type alkylimides chelating resin (PSD-AI). The chelating resin was characterized by scanning electron microscopy, thermogravimetric analysis, infrared spectroscopy, etc. Batch experiments were conducted and effects of different factors on adsorption of uranium(VI) were studied. Results showed that surface of the novel chelating resin was distributed with a large number of pores which could provide more active sites during the adsorption process. At pH = 5.0, reaction temperature 298 K, adsorbent dosage 50.0 mg, initial concentration of U(VI) solution 100.0 mg/L and reaction time 42 h, maximum adsorption capacity of PSD-AI was 75.6 mg/g. (author)
[en] We operated a PbMoO scintillating cryogenic detector of 570 g, produced with archaeological lead. This compound features excellent low temperature characteristics in terms of light yield, 12 keV/MeV for β/γ interactions, and FWHM energy resolution, 11.7 keV at 2.6 MeV. Furthermore, the detector allows for an effective particle identification by means of pulse shape analysis on the heat read-out channel. The implementation of innovative techniques and procedures for the purification of raw materials used for the crystal growth, and the highly-pure archaeological Pb, allowed for the production of large volume high-quality crystal. The overall characteristics of the detector operated at cryogenic temperatures makes PbMoO an excellent compound for neutrino physics applications, especially neutrinoless double-beta studies.
[en] The reach of ab initio many-body theories is rapidly extending over the nuclear chart. However, dealing fully with three-nucleon, possibly four-nucleon, interactions makes the solving of the A-body Schrödinger equation particularly cumbersome, if not impossible beyond a certain nuclear mass. Consequently, ab initio calculations of mid-mass nuclei are typically performed on the basis of the so-called normal-ordered two-body (NO2B) approximation that captures dominant effects of three-nucleon forces while effectively working with two-nucleon operators. A powerful idea currently employed to extend ab initio calculations to open-shell nuclei consists of expanding the exact solution of the A-body Schrödinger equation while authorizing the approximate solution to break symmetries of the Hamiltonian. In this context, operators are normal ordered with respect to a symmetry-breaking reference state such that proceeding to a naive truncation may lead to symmetry-breaking approximate operators. The purpose of the present work is to design a normal-ordering approximation of operators that is consistent with the symmetries of the Hamiltonian while working in the context of symmetry broken (and potentially restored) methods. Focusing on many-body formalisms in which U(1) global-gauge symmetry associated with particle-number conservation is broken (and potentially restored), a particle-number-conserving normal-ordered k-body (PNOkB) approximation of an arbitrary N-body operator is designed on the basis of Bogolyubov reference states. A numerical test based on particle-number-projected Hartree-Fock-Bogolyubov calculations permits to check the particle-number conserving/violating character of a given approximation to a particle-number conserving operator. The PNOkB approximation of an arbitrary N-body operator is formulated. Based on this systematic approach, it is demonstrated that naive extensions of the normal-ordered two-body (NO2B) approximation employed so far on the basis of symmetry-conserving reference states lead to particle non-conserving operators. Alternatively, the PNOkB procedure is now available to generate particle-number-conserving approximate operators. The formal analysis is validated numerically. Using the presently proposed PNOkB approximation, ab initio calculations based on symmetry-breaking and restored formalisms can be safely performed. The future formulation of an angular-momentum-conserving normal-ordered k-body approximation based on deformed Slater determinant or Bogolyubov reference states is envisioned.
[en] Through C+Au collisions at = 200GeV using a multiphase transport (AMPT) model, the azimuthal angle dependences of the Hanbury Brown-Twiss (HBT) radii relative to the second- and third-order participant plane from π-π correlations are discussed. Three initial geometric configurations of C, namely three--cluster triangle, three--cluster chain and Woods-Saxon distribution of nucleons, are taken into account, and their effects on the correlations are investigated. The ratio of the third- to the second-order HBT radii R/R is shown to be a clear probe for three configurations. In addition, this work presents the hadronic rescattering time evolution of the azimuthally dependent HBT radii. From the present study, one can learn that the HBT correlation from identical particles at freeze-out is able to provide the information of different initial configurations as collective flow proposed before.
[en] Carbohydrate based radiotracers have been in routine use as a potential PET imaging agent for tumor targeting, worldwide. The aim of our study was to develop a cost effective and more accessible SPECT based tumor targeted molecular imaging probe. A 1-D-deoxyglucose conjugate was proposed and evaluated as a tumor imaging agent. DTPA-bis(DG) was synthesized by conjugating two molecules of glucose employing a click chemistry approach. It involved a facile methodology, characterization and subsequent radiolabelling with 99mTc with high radiochemical purity and specific activity (187 ± 17 MBq μmol-1) followed by in vitro and in vivo evaluation to prove its potency as an imaging agent. In vitro cytotoxicity studies in the A549 and HEK cell lines showed no substantial toxicity. A cell uptake study revealed that the transportation of [99mTc]DTPA-bis(DG) was GLUT1 independent. In vivo blood kinetic studies in New Zealand rabbits showed fast clearance with a Td1/2 of 28.12 ± 0.63 min and Te1/2 = 101.25 ± 0.34. A significant tumor uptake of 3.88 ± 0.05% ID per g was observed in A549 tumor bearing mice at 4 h p.i. The tumor-to-muscle and tumor-to-blood ratios at 4 h p.i. were 20.46 ± 0.07 and 3.59 ± 0.03 respectively. No significant persistence in any other organs was observed. The tumor (A549) grafted in athymic mice was clearly distinguishable in the gamma-scintigraphy image. The results suggested that this [99mTc]glyco-conjugate would be a promising candidate for cancer targeted imaging. (authors)