Period tripling causes rotating spirals in agitated wet granular layers

Pattern formation of a thin layer of vertically agitated wet granular matter is investigated experimentally. Rotating spirals with three arms, which correspond to the kinks between regions with different colliding phases, are the dominating pattern. This preferred number of arms corresponds to period tripling of the agitated granular layer, unlike predominantly subharmonic Faraday crispations in dry granular matter. The chirality of the spatiotemporal pattern corresponds to the rotation direction of the spirals.Comment: 4 pages, 6 figures, to appear in Physical Review Letter

Copper radionuclides for theranostic applications: towards standardisation of their nuclear data. A mini-review

Copper has several clinically relevant radioisotopes and versatile coordination chemistry, allowing attachment of its radionuclides to biological molecules. This characteristic makes it suitable for applications in molecular imaging or radionuclide targeted therapy. Of particular interest in nuclear medicine today is the theranostic approach. This brief review considers five radionuclides of copper. These are Cu-60, Cu-61, Cu-62, Cu-64, and Cu-67. The first four are positron emitters for imaging, and the last one Cu-67 is a β–-emitting radionuclide suitable for targeted therapy. The emphasis here is on theory-aided evaluation of available experimental data with a view to establishing standardised cross-section database for production of the relevant radionuclide in high purity. Evaluated cross section data of the positron emitters have been already extensively reported; so here they are only briefly reviewed. More attention is given to the data of the 68Zn(p,2p)67Cu intermediate energy reaction which is rather commonly used for production of 67Cu

Radiochemical studies related to the development of new production routes of some diagnostic and therapeutic radionuclides

Nuclear reaction cross section measurements were done in connection with the development of new production routes of the therapeutic and diagnostic radionuclides $^{32}P, ^{71}As, ^{72}As, ^{73}As, ^{74}As, ^{82}Sr, ^{90}Y, ^{153}Sm and ^{169}$Yb. Investigations on the production of n.c.a. $^{73}$Se using novel targetry were also performed. Integral cross sections were measured for the $^{nat}$S(n,p)$^{32}$P, $^{nat}$Zr(n,p)$^{90}$Y and $^{nat}$Eu(n,p)$^{153}$Sm reactions using a 14 MeV d(Be) neutron field. The neutron spectrum was characterised using multiple foil activation and the code SULSA. Existing cross section data were validated within 10 - 15 %, thereby substantiating earlier evaluated and recommended excitation functions of the investigated reactions. It is inferred that for production of radionuclides via the (n,p) reaction, a fast neutron spectral source (e.g. spallation or fusion) would be better suited than a fission reactor. Proton and a-particle induced reactions were investigated in the high-mass area for the production of $^{153}$Sm and $^{169}$Yb via alternative routes. Measurements were done for the first time on the $^{nat}$Nd($\alpha$,n)$^{153}$Sm process over the energy range of 10 to 26.5 MeV and the possible production yield of $^{153}$Sm amounts to 2 GBq. The excitation function of the $^{169}$Tm(p,n)$^{169}$Yb reaction was determined over the energy range from threshold to 45 MeV and compared with the results of nuclear model calculation based on the ALICE-IPPE code. A good agreement was found. The calculated possible production yields are lower than those via the conventional (n,$\gamma$) production route, but the produced $^{153}$Sm and $^{169}$Yb are in no-carrier-added form. Cross sections were also measured with regard to the production of $^{71}As, ^{72}As, ^{73}As and ^{74}$As via the $^{nat}$Ge(p,xn) processes and the results were compared with those from the ALICE-IPPE calculations. Possible yields were calculated together with potential impurities. The various processes contributing to the formation of $^{71}$As in the irradiation of $^{nat}$Ge were analysed by performing some additional measurements on enriched $^{72}$Ge. For the standardisation and validation of data for the production of $^{82}$Sr via the $^{nat}$Rb(p,xn) process, cross section measurements on the formation of the long-lived impurity $^{85}$Sr were done over the energy range of 25 to 45 MeV, a range where a gap still existed. Integral yields were calculated, allowing for an evaluation of the best production conditions of $^{82}$Sr. Preliminary studies on the production of n.c.a. $^{73}$Se via the $^{75}$As(p,xn) reaction using AIAs as a novel target material were also carried out. Thick target yields were determined and first tests on the radiochemical separation of n.c.a. radioselenium from the target were performed

Development of novel radionuclides for medical applications

Medical radionuclide production technology is well established. There is, however, a constant need for further development of radionuclides. The present efforts are mainly devoted to non-standard positron emitters (e.g. 64Cu, 86Y, 124I, 73Se) and novel therapeutic radionuclides emitting low-range β- particles (e. g. 67Cu, 186Re), conversion or Auger electrons (e.g. 117mSn, 77Br) and α-particles (e.g. 225Ac). A brief account of various aspects of development work (i.e. nuclear data, targetry, chemical processing, quality control) is given. For each radionuclide under consideration the status of technology for clinical scale production is discussed. The increasing need of intermediate-energy multiple-particle accelerating cyclotrons is pointed out

Thermochromatographic separation of 45Ti and subsequent radiosynthesis of [45Ti]salan

Due to its favorable decay properties, the non-standard radionuclide 45Ti is a promising PET isotope for tumor imaging. Additionally, titanium complexes are widely used as anti-tumor agents and 45Ti could be used to study their in vivo distribution and metabolic fate. However, although 45Ti can be obtained using the 45Sc(p,n)45Ti nuclear reaction its facile production is offset by the high oxophilicity and hydrolytic instability of Ti4+ ions in aqueous solutions, which complicate recovery from the irradiated Sc matrix. Most available 45Ti recovery procedures rely on ion exchange chromatography or solvent extraction techniques which are time-consuming, produce large final elution volumes, or, in case of solvent extraction, cannot easily be automated. Thus a more widespread application of 45Ti for PET imaging has been hampered. Here, we describe a novel, solvent-free approach for recovery of 45Ti that involves formation of [45Ti]TiCl4 by heating of an irradiated Sc target in a gas stream of chlorine, followed by thermochromatographic separation of the volatile radiometal chloride from co-produced scandium chloride and trapping of [45Ti]TiCl4 in a glass vial at − 78 °C. The recovery of 45Ti amounted to 76 ± 5% (n = 5) and the radionuclidic purity was determined to be > 99%. After trapping, the [45Ti]TiCl4 could be directly used for 45Ti-radiolabeling, as demonstrated by the successful radiosynthesis of [45Ti][Ti(2,4-salan)]