Search results for "RADIOCHEMISTRY"
showing 10 items of 273 documents
Resonance ionization mass spectroscopy for trace determination of plutonium in environmental samples
1997
Resonance ionization mass spectroscopy (RIMS) is a sensitive and isotope selective method and well suited for trace analysis of plutonium in the environment. After the chemical isolation of plutonium from soil, air filters or urine, e.g., it is electrolytically deposited as hydroxide on a tantalum backing and covered with a thin titanium layer. By heating such a sandwich filament in the RIMS-apparatus under vacuum an atomic beam of plutonium is produced. The atoms are ionized by a three-step resonant excitation using pulsed dye lasers, and the ions are mass-selectively detected with a time-of-flight (TOF) spectrometer and a multi channel plate detector. RIMS yields a low detection limit of …
Synthesis of Polyfused Heterocycle Derivatives Containing the Dipyridoimidazole Core by Friedländer’s Reaction: Access to Analogs of Ellipticine
2005
Reaction of 3-amino-2-formylimidazo[l,2-a]pyridine with various aldehydes and ketones by Friedlander's methodology afforded an entry to dipyridoimidazole, tri(tetra)azacyclopenta[b]fluorene, tri(tetra)azabenzo[b]-fluorene and triazaindeno[2,1-b]phenanthrene derivatives. Intercalation with a synthetic oligodeoxynucleotide was examined.
Azide Binding Controlled by Steric Interactions in Second Sphere. Synthesis, Crystal Structure, and Magnetic Properties of [Ni II 2 (L)(μ 1,1 -N 3 )]…
2016
International audience; The dinuclear Ni-II complex [Ni-2(L-2)][ClO4](2) (3) supported by the 28-membered hexaaza-dithiophenolate macro-cycle (L-2)(2-) binds the N-3(-) ion specifically end-on yielding [Ni-2(L-2)(mu(1,1)-N-3)] [ClO4] (7) or [Ni-2(L-2)(mu(1,1)-N-3)][BPh4] (8), while the previously reported complex [Ni2L1(mu(1,3)-N-3)][ClO4] (2) of the 24-membered macrocycle (L-1)(2-) coordinates it in the end-to-end fashion. A comparison of the X-ray structures of 2, 3, and 7 reveals the form-selective binding of complex 3 to be a consequence of its preorganized, channel-like binding pocket, which accommodates the azide anion via repulsive CH center dot center dot center dot pi interactions …
Multifunctional platforms for cancer theranosis
2018
The objective of this thesis was to develop multifunctional tools for cancer theranosis, particularly based on nanotechnology. The work is based on the premise of monomolecular multimodal platform that aims to create the building blocks that can be used for the synthesis of functionalized nanoparticles, bioconjugates or targeted small molecular imaging probes.The initial work focused on the synthesis of the chelator based silane precursors. These novel precursors were employed for the functionalization of AGuIX nanoparticles and have also been implicated in a one pot AGuIX synthesis. Radiolabelling of these nanoparticles was performed with the aim to evaluate the stability of these nanopart…
An Approach on the Hydrogen Absorption in Carbon Black after Gamma Irradiation
2013
In this work, different samples of an industrial carbon black are used to study the hydrogen intake from an over pres-surized atmosphere and its changes due to alteration of its level of crystallinity produced by ¿-irradiation. The monitor-ing of the hydrogen adsorption was made by means of thermogravimetric analysis and by measurements of some elec-trical parameters as the Seebeck coefficient. X-ray diffraction shows that the irradiation diminishes the level of crystal-line perfection. These results show interesting possibilities to use carbon black as cheap hydrogen absorbers.
The response behaviour of LiF:Mg,Cu,P thermoluminescence dosimeters to high-energy electron beams used in radiotherapy
1995
To ensure the effectiveness of radiation-therapy treatments, both in-phantom and in-patient reliable dose measurements are required. Thermoluminescence dosimeters are used commonly for both applications. Among the various available materials, the relatively new LiF:Mg,Cu,P phosphor is a suitable candidate for quality control of in vivo dosimetry in electron-beam therapy. The response behaviour of LiF:Mg,Cu,P chips to 6-21 MeV electron beams used in radiotherapy was studied. Batch homogeneity, dose linearity, sensitivity change after use, dose and dose-rate response, energy dependence and fading characteristics were investigated. The contribution from each factor to the overall uncertainty i…
Self-Radiolysis of Tritiated Water Stored in Zeolites 4A: Production and Behavior of H 2 and O 2
2015
International audience; Radiolysis of confined water and self-radiolysis of tritiated water give rise to several unanswered questions. To take into account this double specificity, we studied systems of zeolites 4A containing tritiated water at different water loading ratios. Two tritiated waters were synthesized at the volumetric activities of 27 and 60 TBq L −1. For each one, five samples were prepared, differentiated by their water loading ratios, expressed in percentage, close to 4%, 7%, 11%, 14%, and 19%. The study of the radiolysis in those systems revealed a double role of zeolites 4A: first, they increase the decomposition of water. Then they enhance the recombination of the major s…
Determination of extremely low (236)U/(238)U isotope ratios in environmental samples by sector-field inductively coupled plasma mass spectrometry usi…
2005
A method by inductively coupled plasma mass spectrometry (ICP-MS) was developed which allows the measurement of (236)U at concentration ranges down to 3 x 10(-14)g g(-1) and extremely low (236)U/(238)U isotope ratios in soil samples of 10(-7). By using the high-efficiency solution introduction system APEX in connection with a sector-field ICP-MS a sensitivity of more than 5,000 counts fg(-1) uranium was achieved. The use of an aerosol desolvating unit reduced the formation rate of uranium hydride ions UH(+)/U(+) down to a level of 10(-6). An abundance sensitivity of 3 x 10(-7) was observed for (236)U/(238)U isotope ratio measurements at mass resolution 4000. The detection limit for (236)U a…
Separation of 90Nb from zirconium target for application in immuno-PET
2014
Abstract Fast progressing immuno-PET asks to explore new radionuclides. One of the promising candidates is 90Nb. It has a half-life of 14.6 h that allows visualizing and quantifying biological processes with medium and slow kinetics, such as tumor accumulation of antibodies and antibodies fragments or drug delivery systems and nanoparticles. 90Nb exhibits a positron branching of 53% and an average kinetic energy of emitted positrons of E mean =0.35 MeV. Currently, radionuclide production routes and Nb V labeling techniques are explored to turn this radionuclide into a useful imaging probe. However, efficient separation of 90Nb from irradiated targets remains in challenge. Ion exchange based…
Marquage de molécules biologiques par des complexes de radiométaux à base de polyamines macrocycliques
2012
This work conducted at the “Institut de Chimie Moléculaire de l’Université de Bourgogne” carries at first on the synthesis of bifunctional chelating agents suitable for the chelation of trivalent radiometals, including indium-111. The greater part of this work was then dedicated to the grafting of a DOTA derivative bifunctional chelating agent on different antibodies or fragments of monoclonal antibodies: trastuzumab (anti-HER2 treatment of breast cancer), cetuximab (anti EGFR, treatment of many cancers, including colorectal cancer) and abciximab (antiplatelet). Particular attention was paid to the characterization of various immunoconjugates. The critical step of this thesis consisted in t…