Radiochemistry最新文献

¹⁰⁵Rh is one of the promising beta-emitters for therapeutic purposes in nuclear medicine, but its use is limited, due to in part its low availability, which dictates the search for new effective ways to produce it. In this work, the radionuclide composition of a PdCl₂ target irradiated by bremsstrahlung photons is determined and a method is proposed for recovery carrier free ¹⁰⁵Rh from it using a commercial DGA sorbent, which ensures a high degree of purification of the target isotope. In future, the studies carried out may contribute to the practical application of ¹⁰⁵Rh to nuclear medicine.

The properties of H₂O₂ and its reactions with lanthanide and actinide ions are considered. The potential values of pairs involving H₂O₂ in acidic and alkaline solutions are given. Depending on the oxidative potential of the f-element ion and pH, H₂O₂ exhibits oxidizing or reducing properties. The kinetics and mechanisms of reactions of H₂O₂ with lanthanides(II–IV) and with actinides(III–VII) in acidic, carbonate, and alkaline media have been analyzed. Ions of f-elements(III–VI) form peroxide complexes. The peroxo group occupies either one (OOH) or two (OO) coordination sites. U(VI), Np(IV) binds up to 3 peroxo groups. Oxidation or reduction reactions proceed intramolecularly. In the case of Yb²⁺, Sm²⁺, U³⁺, Ce⁴⁺ (in an acid solution), Pr(IV) and Am(IV) (in a weakly acidic medium), the bimolecular rate constants are 10⁵–n × 10⁶ L/(mol s), which exceeds the rate of ligand exchange in the coordination sphere of the f-element ion. Therefore, charge transfer occurs in the outer sphere. Coordination spheres of Ce(IV) oxalate, Tb(IV) with P₂W₁₇O₆₁^10–, and Np(VI) with NO₃^– slow down the charge transfer between H₂O₂ and the f-element ion. H₂O₂ arising during the radiolysis of aqueous solutions is in an excited state and is more active than H₂O₂ introduced from the outside. Of particular interest are the reactions of H₂O₂ with ions of f-elements in strongly complexing or nonaqueous (organic) media, as well as structural studies of solid compounds of peroxides of f-elements.

[³H]Hyaluronic acid with a molecular weight of 2.37 MDa and a specific radioactivity of 35 GBq/g was obtained using the tritium thermal activation method. Tritium labeled hyaluronic acid (HA) with a molecular weight of 2.37, 0.20, and 0.10 MDa were used to study their adsorption on hydroxyapatite (HAP) in two textural modifications: aqueous suspension and powder. Differences in adsorption kinetics and adsorption isotherms were observed due to variations in the interaction between polysaccharide molecules and the sorbent forms under consideration. The adsorption isotherms of HA on HAP were proven linear. It is shown that strong HA–HAP complexes are formed, and no desorption of HA into water and 0.9% NaCl solution were detected in 2 days.

Atherosclerosis is one of the most important problems of modern medicine. It involves changes in the structure and inner lining of the arteries. Studying chemical elements directly in vascular tissues allows understanding the mechanisms of evolvement of cardiovascular diseases, in particular, atherosclerosis. This study is aimed at developing the neutron activation technique for the analysis of atherosclerotic plaques formed at various stages of the atherosclerosis and studying their composition. The content of 13 elements in lipid, fibrous, ulcerated, and calcific plaques was determined using the developed method. It was established that upon evolving atherosclerosis, the content of a number of essential elements changes, the content of calcium, strontium, selenium, zinc and iron increases, and the bromine content decreases. Also, it was suggested that iron plays a role in the evolution of atherosclerotic vascular lesions.

The kinetics of disproportionation of Pu(V) in EDTA solutions with pH 2.5–4.8 at a temperature of 45°C was studied using the spectrophotometric method. Pu(V) was obtained by reduction of Pu(VI) with EDTA ions. The rate of disproportionation in the pH range 2.9–4.8 is described by the equation d[Pu(V)]/dt = 2k[Pu(V)]². With increasing pH the value of 2k decreases. In a solution of 28 mM EDTA at pH 2.91, 45°С, and an ionic strength of 0.09 and 1.0 M, 2k is 0.064 and 0.040 M^–1 s^–1, respectively. A dimer formed from PuO₂⁺·5H₂O and the PuO₂HY^2–·nH₂O complex becomes an activated complex. Its decomposition leads to the appearance of Pu(IV) and Pu(VI). The latter, being bound to Y, is reduced intramolecularly to Pu(V). The activation energy is 86 kJ/mol (25–45°C).

Various methods of introducing deuterium into dopamine using isotope exchange are considered. The best result is achieved by isotope exchange with deuterated water at 190°C for 30 min using (a) trifluoroacetic acid as a catalyst and (b) 5% Pd/Al₂O₃ catalyst presaturated with deuterium gas. In the first case, the yield of deuterated dopamine was 65–70%, and the average deuterium content was 2.4–2.5 at./molecule. In the second case, the yield decreased to 35–40%, but the deuterium content increased to 3.50–3.60 at./molecule. The obtained result highlights the effectiveness of an integrated approach to introducing hydrogen isotopes into organic molecules, when activated hydrogen isotope species are formed on the catalyst and the substance deposited on it, which contribute to increasing the efficiency of isotope exchange with deuterated water at heating.

The conditions for introducing deuterium into Trp-Pro-Pro-Trp and Boc-Trp-Pro-Pro-Trp by isotope exchange with D₂O in the presence of a 5% Pd/Al₂O₃ catalyst were developed. The thermal stability of Trp-Pro-Pro-Trp upon introduction of deuterium was significantly lower than that of the Boc-protected peptide. The yield of deuterated Trp-Pro-Pro-Trp did not exceed 10–15%, and the inclusion of deuterium was about 0.9–1.1 at./molecule at 125°C. The introduction of deuterium into Boc-Trp-Pro-Pro-Trp was possible at 150°C, which increased the deuterium content to 3.75 at./molecule. It was found that the tryptophan fragment of the molecule contains approximately 2 times more deuterium than the proline fragment. It was found that pretreatment of Boc-Trp-Pro-Pro-Trp with deuterium gas not only activates isotope exchange, but also promotes the removal of Boc protection. The data obtained indicate that the reason for this phenomenon is associated with the generation of deuterium cations on Boc-Trp-Pro-Pro-Trp molecules by the catalyst.

The effect of irradiation of a strongly basic vinylpyridine anion exchange resin of the VP-1AP grade in nitrate form on the onset temperatures of exothermic reactions, thermal effects and the composition of gaseous thermolysis products of VP-1AP was studied. It was established that the onset temperatures of exothermic reactions for an irradiated anion exchange resin are reduced by 59–100°C. The total thermal effect of thermolysis of the irradiated sorbent is 67% less than that of the non-irradiated one. An analysis of the composition of the gaseous thermolysis products of the VP-1AP irradiated anion exchange resin showed that at the first stage of thermolysis, the functional groups of the sorbent are predominantly decomposed. At higher temperatures, the process of degradation of the styrene-divinylbenzene anion exchange resin matrix was ​detected. The significant influence of irradiation on the conditions for the safe use of anion exchange resins during separation of radionuclides from nitric acid solutions was demonstrated.

This study was aimed to prepare immunoradiometric (IRMA) system using solid-phase magnetizable cellulose particles coupled with luteinizing hormone (LH) to determine LH in human serum. The LH-IRMA system was designed through preparation of LH polyclonal antibody (anti-LH), ¹²⁵I-LH tracer, and LH standards. Production of anti-LH was carried out through immunization of three Balb/C mice with LH-BSA immunogen. Magnetizable cellulose particles were activated using 1,1’-carbonyldiimidazole (CDI) and coupled with purified anti-LH. Optimization and validation of LH-IRMA were undertaken. The results obtained show that the local solid-phase magnetic particle LH-IRMA is a sensitive, specific, precise, and accurate method for measuring the LH concentration in human serum and can be used as a diagnostic tool for some disorders such as infertility in females and impotence in males.