The experimental E1 strength distribution below 4 MeV in rare-earth nuclei suggests a local breaking of isospin symmetry. In addition to the octupole states, additional J^{π}=1^{-} states with ...enhanced E1 strength have been observed in rare-earth nuclei by means of (γ,γ') experiments. By reproducing the experimental results, the spdf interacting boson model calculations provide further evidence for the formation of an α cluster in medium-mass nuclei and might provide a new understanding of the origin of low-lying E1 strength.
We discuss hereby the Zirconium(IV) aqueous chemistry for radioimaging and aspects of bioconjugation of the 89Zirconium-labelled chelators to monoclonal antibodies and targeting peptides for their ...use in the targeted imaging of prostate cancer at the pre-clinical level. Selected nanomaterials for the preparation of 89Zr(IV)-tagged nanoprobes are also highlighted.
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•Zirconium(IV) aqueous chemistry for radioimaging.•Bioconjugation of the 89Zirconium-labelled chelators.•Applications of 89Zr-labelled biomolecules in the targeted imaging of prostate cancer.•Selected nanomaterials for the preparation of 89Zr(IV) tagged nanoprobes.
In recent years, the use of metallic isotopes for nuclear imaging techniques such as single photon emission computed tomography (SPECT) and positron emission tomography (PET) has become an area of much interest. In particular, PET is a molecular imaging modality that relies on the detection of two antiparallel, co-linear gamma rays (511 keV) emitted when a positron undergoes annihilation with an electron. PET isotopes of interest in medical practice are numerous and their use depends on their half-lives and introduction in the compounds of interest. These include: nitrogen-13 (t1/2 = 10 min), carbon-11 (t1/2 = 20 min), fluorine-18 (t1/2 = 110 min) and metallic isotopes such as gallium-68 (t1/2 = 68 min), titanium-45 (t1/2 = 3.08 h), copper-64 (t1/2 = 12.7 h), manganese-52 (t1/2 = 5.59 d) or zirconium-89 (t1/2 = 3.3 d). 89Zr has emerged as a promising isotope for radiotracer design and in vivo delivery, on basis of its ideal half-life matching the biological half-life of antibodies, antibody fragments and nanomedicines leading to high-resolution PET images for the pre-clinical and clinical investigations of a number of conditions including the prospective use in prostate cancers in the search of new diagnostic biomarkers. The availability of a plethora of chelators satisfying the coordination number of 8 such as siderophore-like chelators and recently nanoparticles conferring high kinetic and thermodynamic stabilities provides various designs and versatility in chemistry and radiochemistry. The aqueous chemistry of 89Zr is certainly of high importance for antibody-based imaging due to the match between the physical half- life of the nuclide and the biological half-life of the targeting vector, but mostly if there are no small molecules with more rapid pharmacokinetics available. This mini-review highlights some of the recently accounted advantages and disadvantages of current biomolecule-tagging techniques and proposes subtle radiotracer design changes that may be introduced in order to obtain a highly efficient targeted imaging with zirconium-labelled chemical entities and nanoconstructs. These may be of relevance to preclinical and clinical research towards the diagnosis of cancer in general, whilst highlighting some of the prostate cancer targeting approaches from the recent 89Zr-focused radiochemistry literature.
The generation of the collective nuclear E1 response is intimately connected to the breaking of proton-neutron symmetry. In this contribution, we present our recent results on a possible α-cluster ...dipole mode, which were obtained in the framework of the spdf interacting boson model. These extended studies of the low-lying E1 response support the general occurence of α-cluster dipole states in atomic nuclei.
Half-lives of the low-lying yrast states of 212Po have been measured using the delayed coincidence fast-timing method. We report on the first measurement of the 41+ half-life, as well as a new ...measurement of the 61+ half-life with improved accuracy compared to previous studies. The extracted lifetime of the 41+ and 61+ state have been determined to be 100(14) ps and 1.66(28) ns respectively. With these measurements, precise values are now available for the reduced transition strengths B(E2) of all ground state band levels in 212Po up to the first 8+ state, in particular B(E2; 41+→21+) = 9.4(13) W.u. and B(E2;61+→41+) = 8.7(15) W.u. Comparison of the new available data with an α-clustering model calculation provides evidence that the inclusion of the α-cluster degree of freedom significantly improves agreement with experimental data compared to earlier shell model calculations.
We report on the first (p,p′γ) experiments at Ep=80 MeV to investigate the Pygmy Dipole Resonance (PDR) in the semi-magic nucleus 140Ce. This experiment is the latest in a series of experiments to ...investigate the PDR with different complementary probes to provide a multi-messenger data set on the properties of the PDR in 140Ce. In addition, calculations within the Quasi-particle Phonon Model (QPM) have been performed. Cross sections have been calculated for proton- as well as α-scattering reactions based on the transition densities obtained from the QPM, not only at the RPA level, but including the full model space of up to 3p–3h configurations. This allows for the first time to compare the calculations to the experimental results on an absolute scale for single excitations. Agreement between QPM and experiment is observed, which proves the high accuracy of the calculated transition densities for individual PDR states.
The aim of this investigation is to reveal the structure of 150Sm by measuring for the first time a rather complete set of energy levels of this nucleus up to 4 MeV and determine the total angular ...momentum of the states. The study was carried out at the 14 MV Tandem Accelerator of the Munich universities by measuring complete angular distributions for states up to 4 MeV excited in the direct two-neutron transfer reaction 152Sm(p,t)150Sm at an incident energy of 22 MeV. Emphasis was put on determining the 0+ excited states, which are some of the most important excitations in the rare-earth region. Up to now only three 0+ levels are known in 150Sm, and investigating the distribution of energy and intensity of these excited states also at higher excitation energy might reveal the main contributions in the wave functions of this nucleus.
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A fast-timing method to determine lifetimes of nuclear states in the sub-nanosecond domain is presented. It is based on in-beam measurements of triple-gamma coincidences in heavy-ion ...fusion-evaporation reactions, performed with an array of HPGe and LaBr
3
:Ce detectors. The high-energy resolution HPGe detectors are used to define de-exciting cascades, while the fast LaBr
3
:Ce detectors are used to determine the decay time spectra of selected levels fed by these cascades. A special method to treat the time information of an array of fast detectors is employed in order to fully use the efficiency of the array. Two measurements are presented to illustrate the method: a re-determination of the known half-life
ns of the
keV,
level in
107
Cd (test experiment), and the determination of a half-life
ps for the
keV,
state of
199
Tl .
Since their advent, various 3D printing technologies have been developed, out of which the Fused Filament Fabrication, FFF has completely revolutionized the industry in the last years. Classical FFF ...printers are using a thermoplastic filament, which is heated to its melting point and then extruded layer by layer to materialize a three dimensional part. One of the most important subassemblies of the 3D printer which is the most representative is the extrusion sub-assembly system and the thermal demands to which is subjected. In this article, one original constructive variant of the extruding sub-assembly system has been conceived and thermal analyses of the variant was performed by using the finite element method so as to be used not only for printing parts made of plastic materials in filament form, but also plastic materials in the powder state form at the Technical University of Cluj-Napoca, Romania.
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