The paper introduces two reverse-tandem schemes of the 140 Ba → 140 La radionuclide generator which allow obtaining the daughter radionuclide 140 La for different applications in nuclear spectroscopy and as a tracer for radiochemical separations. The tandem generator system includes two stages: a chromatographic separation of parent and daughter radionuclides based on the main reverse column (cation-exchange column), and purification based on tandem column (extraction column). The main chromatographic separation is carried out in acetic acid media. Use of 140 La preparation with high specific activity in the perturbed angular γγ-correlation method is discussed.

Targeted Alpha Therapy (TAT) holds significant promise as a localized treatment for cancer. Encouraging clinical results from using peptides and antibodies labeled with alpha emitters to treat patients with metastatic cancers, particularly those who have not responded to other therapies, provide compelling evidence of TAT's potential. To fully realize the benefits of TAT, it is essential to carefully select appropriate radionuclides and targeting delivery systems to maximize therapeutic efficacy while minimizing nonspecific toxicity to healthy tissues. This review explores key radiochemical, radiopharmaceutical, and radiation-biological considerations for current TAT candidates, and proposes additional potential candidates, establishing a foundation and criteria for the ongoing development of TAT radiopharmaceuticals.

In recent years, radiopharmaceuticals have been increasingly used for diagnostics and treatment of cancer. In addition to a biological vector, a modern radiopharmaceutical includes a chelator that binds the radionuclide, as well as a linker for connecting the vector and the chelator. The development of such an approach requires the improvement of methods for obtaining and purifying radionuclides, and the development of methods for the synthesis of radiopharmaceuticals, i.e., preparative direction. It is also necessary to search for new vectors and chelators. This implies the development of methods for analyzing the properties of radiopharmaceuticals in general, as well as their precursors, i.e., analytical direction. In this review, we describe the prerequisites for successfully solving a wide range of challenges in these two areas of nuclear medicine at the Scientific and Experimental Department of Nuclear Spectroscopy and Radiochemistry of the Laboratory of Nuclear Problems of the Joint Institute for Nuclear Research (LNP JINR). These prerequisites are due to rich experience in obtaining the widest range of radionuclides and their application for various spectrometric studies. Both the past and present works on radiopharmaceutical topics carried out in the department are described, and ways of future development are outlined.

The geometry of dendritic spines has a major impact on signal transmission at excitatory synapses. To study it in detail we raised transgenic mice expressing an intrinsic green fluorescent protein-based plasma membrane marker that directly visualizes the cell surface of living neurons throughout the brain. Confocal imaging of developing hippocampal slices showed that as dendrites mature they switch from producing labile filopodia and polymorphic spine precursors to dendritic spines with morphologies similar to those reported from studies of adult brain. In images of live dendrites these mature spines are fundamentally stable structures, but retain morphological plasticity in the form of actin-rich lamellipodia at the tips of spine heads. In live mature dendrites up to 50% of spines had cup-shaped heads with prominent terminal lamellipodia whose motility produced constant alterations in the detailed geometry of the synaptic contact zone. The partial enveloping of presynaptic terminals by these cup-shaped spines coupled with rapid actin-driven changes in their shape may operate to fine-tune receptor distribution and neurotransmitter cross-talk at excitatory synapses.

To find a high purity flux for low background experiments is one of the most challenging problems. In this work, we report the production process of a highly purified ammonium acetate flux solution for low background experiments. A sub-distilled method has been used to purify initial precursors from contamination for the syntheses of final product. As a result, a high purity ammonium acetate solution was synthesized with a minimum content of elements which collectively represent the main source of background radiation (K  < 2.3 × 10–8 g/g, Th  < 2.6 × 10–11 g/g and U  < 1 × 10–11 g/g). An Estimation of the impurity content of the product has been performed with Instrumental neutron activation analysis, inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry.

Radiochemical separation and purification play an important role in the production and synthesis of radiopharmaceuticals in modern nuclear medicine. Several important criteria that need to be considered when choosing appropriate radiochemical separation methods are discussed in the present work. This review is designed to give an overview of important aspects of radiochemical separation for medical radionuclides and to bridge it with their production and chelation. Several important parameters, such as radionuclidic and radiochemical purity, specific activity are discussed. With this review, the authors would like to stress the importance of radiochemistry for radiopharmaceutical science, as it is very often underestimated.

Ammonium chloride is a widely available non-corrosive and non-toxic chemical. When in contact with protein NH4Cl is non-destructive and allows softer conditions for labeling of organic substances. These properties make NH4Cl appropriate for use in multiple areas such as pharmaceutical production, low-background research, etc. For such purposes, a multitude of pure elements could be applied. In order to obtain pure elements their separation (purification) is necessary. One of the most successful methods of elements separation is ion exchange. In this work, we study the distribution coefficient of 60 elements on anion exchange (Dowex 1-x8) and cation exchange (Dowex 50w-x8) resins with NH4Cl solutions with varying concentrations via ICP-MS.

Solvent extraction of U(VI), Th(IV), Am(III) and lanthanides(III) from aqueous nitric acid solutions with 1,2,3-triazole-modified carbamoylmethylphosphine oxide (L) and [C(4)mim][Tf2N] ionic liquid dissolved in 1,2-dichloroethane was studied. A considerable synergistic effect in this system was observed. This effect is associated with the high hydrophobicity of the IL anions which participate in the formation of metal extracted ion species. The influence of aqueous and organic phases on the extraction efficiency was elucidated and stoichiometry of the complexes extracted was determined. The synergistic effect for metal ion extraction from aqueous nitric acid solutions with compound L and [C(4)mim][Tf2N] in 1,2-dichloroethane becomes weaker when the acidity of the aqueous phase increases. The partition of Tf2N- anions between the organic and aqueous phases is the major factor governing the extractability of metal ions in the L-IL synergistic system. The interaction of L with HTf2N and HNO3 also substantially affects the efficiency of metal ion extraction.

The distribution coefficients of Hf(IV) and Lu(III) between Dowex 50W×8 cation exchanger or Dowex 1×8 anion exchanger and mixed HCl–H 2 C 2 O 4 solutions and between Dowex 50W×8 cation exchanger or Dowex 1×8 anion exchanger and citric acid solutions were determined. A number of modifications of the 172 Hf → 172 Lu generator, based on reverse separation schemes, were examined. Systems consisting of an anion-exchange resin and a solution of appropriate organic acid were taken as a chemical basis of the generator. Irreversible sorption of 172 Lu in generator columns was studied. The optimum operation mode of the 172 Hf → 172 Lu generator based on the reverse-tandem scheme with periodic transfer of the parent radionuclide into the liquid phase was determined.

68Ga (T1/2 = 68 min) in complexes with peptides is used in positron emission tomography for diagnostics of neuroendocrine tumors. The most promising strategy for 68Ga production is usage of the radionuclide generator 68Ge → 68Ga. In this research, the sorption behavior of Ge(IV) and Ga (III) has been studied. The distribution coefficients (Kd) of Ge(IV) on the anion exchange (Dowex 1×8) and cation exchange (Dowex 50×8) resins in various ethanedioic and hydrochloric acid solutions were determined. For each ion exchange resin, four series of measurements were carried out, in which the concentration of oxalic acid was fixed (0.001 M, 0.003 M, 0.005 M, 0.01 M), and the concentrations of hydrochloric acid ranged from 0 to 3 M. Based on the distribution coefficients, the chemical scheme of the radionuclide generator 68Ge → 68Ga has been developed. The chemical system is based on the anion exchange resin Dowex 1×8 and mixture of 0.005 M C2H2O4 / 0.33 M HCl. Several types of the generators with direct and reverse mode of elution were tested and the optimal scheme was determined. Elution of the generators was performed once a day with 8 ml of 0.005 M C2H2O4 / 0.33 M HCl solution. The 68Ga yield and the 68Ge breakthrough are comparable for all the systems.

Utilization of (p, 4n) reaction channel for the production of medical radionuclides became very attractive with commercial availability of medium energy cyclotrons. Significantly higher yields and radionuclidic purity may open new perspectives for several novel and some of the radionuclides previously have not been considered due to production difficulties. In present work, we show the proof-of-principle study on the production of 86Y for Positron Emission Tomography imaging via radionuclide generator 86Zr → 86Y. Production suitability of 86Zr from natural yttrium target and radiochemical separation strategies were tested. In addition, two generator systems were proposed and evaluated.

The KLM+KLN Auger electron spectrum of rubidium (Z=37) emitted in the electron capture decay of radioactive 83 Sr in a polycrystalline platinum matrix and also 85 Sr in polycrystalline platinum and carbon matrices as well as in an evaporated layer onto a carbon backing was experimentally studied in detail for the first time using a combined electrostatic electron spectrometer.Energies, relative intensities, and natural widths of fifteen basic spectrum components were determined and compared with both theoretical predictions and experimental data for krypton (Z=36).Relative spectrum line energies obtained from the semi-empirical calculations in intermediate coupling scheme were found to agree within 3σ with the measured values while disagreement with experiment exceeding 3σ was often observed for values obtained from our multiconfiguration Dirac-Hartree-Fock calculations.The absolute energy of the dominant spectrum component given by the semi-empirical approach agrees within 1σ with the measured value.Shifts of + (0.2±0.2) and -(1.9±0.2) eV were measured for the dominant KLM spectrum components between the 85 Sr sources prepared by vacuum evaporation on and implanted into the carbon foil, respectively, relative to 85 Sr implanted into the platinum foil.A value of (713±2) eV was determined for the energy difference of the dominant components of the KLM+KLN Auger electron spectra of rubidium and krypton generated in the polycrystalline platinum matrix.From the detailed analysis of the measured data and available theoretical results, the general conclusion can be drawn that the proper description of the KLM+KLN Auger electron spectrum for Z around 37 should still be based on intermediate coupling of angular momenta taking into account relativistic effects.

(90)Nbhas an intermediate half-life of 14.6h, a high positron branching of 53% and optimal beta(+) emission energy of only E-mean 0.35MeV per decay. These favorable characteristics suggest it may be a potential candidate for application in immuno-PET. Our recent aim was to conduct studies on distribution coefficients for Zr-IV and Nb-V in mixtures of HCl/H2O2 and HCl/oxalic acid for anion exchange resin (AG 1x8) and UTEVA resin to develop a "direct flow" separation strategy for Nb-90. The direct flow concept refers to a separation accomplished using a single eluent on multiple columns, effectively streamlining the separation process and increasing the time efficiency. Finally, we also demonstrated that this separation strategy is applicable to the production of the positron emitter Nb-90 via the irradiation of molybdenum targets and isolation of Nb-90 from the irradiated molybdenum target.

The article describes the results of experiments conducted on pigs to determine the effect of plutonium, which is the most radiotoxic and highly active element in the range of mixed fuel (U0.8Pu0.2)O2 fission products, on living organisms. The results will allow empirical prediction of the emergency plutonium radiation dose for various organs and tissues of humans in case of an accident in a reactor running on mixed fuel (U0.8Pu0.2)O2.

Using internal conversion electron spectroscopy, improved energy 21 541.5±0.5 eV was determined for the 21.5keV M1 + E2 nuclear transition in 151Eu populated in the electron capture decay of 151Gd . This value was found to agree well with the present adopted value but is much more accurate. A value of 0.0305±0.0011 derived for the E2 admixture parameter \( \vert\delta(E2/M1)\vert\) from the measured conversion electron line intensities corresponds to the present adopted value. A possible effect of nuclear structure on the multipolarity of the 21.5 keV transition was also investigated.