Chemistry has arrived on the shore of the Island of Stability with the first chemical investigation of the superheavy elements Cn, 113, and 114. The results of three experimental series leading to ...first measured thermodynamic data and qualitatively evaluated chemical properties for these elements are described. An interesting volatile compound class has been observed in the on-line experiments for the elements Bi and Po. Hence, an exciting chemical study of their heavier transactinide homologues, elements 115 and 116 is suggested.
Snake envenomation is a common but neglected disease that affects millions of people around the world annually. Among venomous snake species in Brazil, the tropical rattlesnake (Crotalus durissus ...terrificus) accounts for the highest number of fatal envenomations and is responsible for the second highest number of bites. Snake venoms are complex secretions which, upon injection, trigger diverse physiological effects that can cause significant injury or death. The components of C. d. terrificus venom exhibit neurotoxic, myotoxic, hemotoxic, nephrotoxic, and cardiotoxic properties which present clinically as alteration of central nervous system function, motor paralysis, seizures, eyelid ptosis, ophthalmoplesia, blurred vision, coagulation disorders, rhabdomyolysis, myoglobinuria, and cardiorespiratory arrest. In this study, we focused on proteomic characterization of the cardiotoxic effects of C. d. terrificus venom in mouse models. We injected venom at half the lethal dose (LD50) into the gastrocnemius muscle. Mouse hearts were removed at set time points after venom injection (1 h, 6 h, 12 h, or 24 h) and subjected to trypsin digestion prior to high-resolution mass spectrometry. We analyzed the proteomic profiles of >1300 proteins and observed that several proteins showed noteworthy changes in their quantitative profiles, likely reflecting the toxic activity of venom components. Among the affected proteins were several associated with cellular deregulation and tissue damage. Changes in heart protein abundance offer insights into how they may work synergistically upon envenomation.
Venom of the tropical rattlesnake (Crotalus durissus terririficus) is known to be neurotoxic, myotoxic, nephrotoxic and cardiotoxic. Although there are several studies describing the biochemical effects of this venom, no work has yet described its proteomic effects in the cardiac tissue of mice. In this work, we describe the changes in several mouse cardiac proteins upon venom treatment. Our data shed new light on the clinical outcome of the envenomation by C. d. terrificus, as well as candidate proteins that could be investigated in efforts to improve current treatment approaches or in the development of novel therapeutic interventions in order to reduce mortality and morbidity resulting from envenomation.
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•C. d. terrificus rattlesnake venom treatment of mice showed changes in cardiac protein profile•C. d. terrificus venom modulated proteins involved in biological and cellular process - C. d. terrificus venom modulated proteins related to molecular function and phenotypic profiles•C. d. terrificus venom modulated Gene Ontology categories related to cardiac cardiac tissue damage•Network analysis showed disturbances of proteins related to cardiac tissue damage
Terbium-149 (T
= 4.1 h, E
= 3.98 MeV (16.7%), 28 µm range in tissue) is a radionuclide with potential for targeted alpha therapy. Due to the negligible emission of α-emitting daughter nuclides, ...toxicity to healthy tissue may be reduced in comparison with other α-particle emitters. In this study, terbium-149 was produced via 1.4 GeV proton irradiation of a tantalum target at the CERN-ISOLDE facility. The spallation products were mass separated and implanted on zinc-coated foils and, later, radiochemically processed. Terbium-149 was separated from the co-produced isobaric radioisotopes and the zinc coating from the implantation foil, using cation-exchange and extraction chromatographic techniques, respectively. At the end of separation, up to 260 MBq terbium-149 were obtained with > 99% radionuclidic purity. Radiolabeling experiments were performed with DOTATATE, achieving 50 MBq/nmol apparent molar activity with radiochemical purity > 99%. The chemical purity was determined by inductively coupled plasma-mass spectrometry measurements, which showed lead, copper, iron and zinc only at ppb level. The radiolabeling of the somatostatin analogue DOTATATE with
TbTbCl
and the subsequent in vivo PET/CT scans conducted in xenografted mice, showing good tumor uptake, further demonstrated product quality and its ability to be used in a preclinical setting.
Experimental investigations of transactinoide elements provide benchmark results for chemical theory and probe the predictive power of trends in the periodic table. So far, in gas-phase chemical ...reactions, simple inorganic compounds with the transactinoide in its highest oxidation state have been synthesized. Single-atom production rates, short half-lives, and harsh experimental conditions limited the number of experimentally accessible compounds. We applied a gas-phase carbonylation technique previously tested on short-lived molybdenum (Mo) and tungsten (W) isotopes to the preparation of a carbonyl complex of seaborgium, the 106th element. The volatile seaborgium complex showed the same volatility and reactivity with a silicon dioxide surface as those of the hexacarbonyl complexes of the lighter homologs Mo and W. Comparison of the product’s adsorption enthalpy with theoretical predictions and data for the lighter congeners supported a Sg(CO)₆ formulation.
Development of interfaces for sample introduction from high pressures is important for real-time online hyphenation of chromatographic and other separation devices with mass spectrometry (MS) or ...accelerator mass spectrometry (AMS). Momentum separators can reduce unwanted low-density gases and introduce the analyte into the vacuum. In this work, the axial jet separator, a new momentum interface, is characterized by theory and empirical optimization. The mathematical model describes the different axial penetration of the components of a jet-gas mixture and explains the empirical results for injections of CO2 in helium into MS and AMS instruments. We show that the performance of the new interface is sensitive to the nozzle size, showing good qualitative agreement with the mathematical model. Smaller nozzle sizes are more preferable due to their higher inflow capacity. The CO2 transmission efficiency of the interface into a MS instrument is ∼14% (CO2/helium separation factor of 2.7). The interface receives and delivers flows of ∼17.5 mL/min and ∼0.9 mL/min, respectively. For the interfaced AMS instrument, the ionization and overall efficiencies are 0.7–3% and 0.1–0.4%, respectively, for CO2 amounts of 4–0.6 μg C, which is only slightly lower compared to conventional systems using intermediate trapping. The ionization efficiency depends on to the carbon mass flow in the injected pulse and is suppressed at high CO2 flows. Relative to a conventional jet separator, the transmission efficiency of the axial jet separator is lower, but its performance is less sensitive to misalignments.
Radionuclide production and development has a long history at the Paul Scherrer Institute (PSI) and dates back to the founding times of its forerunner institutions: the Federal Institute for Reactor ...Research and the Swiss Institute for Nuclear Research. The facilities used for this purpose have evolved substantially over the last five decades. Many radiometals in use today, as radiopharmaceuticals, are for the diagnosis and treatment of disease, with the most popular means of detection being Positron Emission Tomography. These positron emitters are easily produced at low proton energies using medical cyclotrons, however, developments at these facilities are lacking. Currently, the fixed 72 MeV proton beam at PSI is degraded at IP2 irradiation station to provide the desired energy to irradiate targets to produce the likes of
Sc,
Sc and
Cu as a proof of principle, which are of great interest to the nuclear medicine community. This development work can then be implemented at facilities containing medical cyclotrons. A history of the development of radionuclides at PSI, along with current development and projects with partner institutions, is described.
The heaviest elements to have been chemically characterized are seaborgium (element 106), bohrium (element 107) and hassium (element 108). All three behave according to their respective positions in ...groups 6, 7 and 8 of the periodic table, which arranges elements according to their outermost electrons and hence their chemical properties. However, the chemical characterization results are not trivial: relativistic effects on the electronic structure of the heaviest elements can strongly influence chemical properties. The next heavy element targeted for chemical characterization is element 112; its closed-shell electronic structure with a filled outer s orbital suggests that it may be particularly susceptible to strong deviations from the chemical property trends expected within group 12. Indeed, first experiments concluded that element 112 does not behave like its lighter homologue mercury. However, the production and identification methods used cast doubt on the validity of this result. Here we report a more reliable chemical characterization of element 112, involving the production of two atoms of 283112 through the alpha decay of the short-lived 287114 (which itself forms in the nuclear fusion reaction of 48Ca with 242Pu) and the adsorption of the two atoms on a gold surface. By directly comparing the adsorption characteristics of 283112 to that of mercury and the noble gas radon, we find that element 112 is very volatile and, unlike radon, reveals a metallic interaction with the gold surface. These adsorption characteristics establish element 112 as a typical element of group 12, and its successful production unambiguously establishes the approach to the island of stability of superheavy elements through 48Ca-induced nuclear fusion reactions with actinides.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Muonic atom spectroscopy–the measurement of the x rays emitted during the formation process of a muonic atom–has a long standing history in probing the shape and size of nuclei. In fact, almost all ...stable elements have been subject to muonic atom spectroscopy measurements and the absolute charge radii extracted from these measurements typically offer the highest accuracy available. However, so far only targets of at least a few hundred milligram could be used as it required to stop a muon beam directly in the target to form the muonic atom. We have developed a new method relying on repeated transfer reactions taking place inside a 100 bar hydrogen gas cell with an admixture of 0.25% deuterium that allows us to drastically reduce the amount of target material needed while still offering an adequate efficiency. Detailed simulations of the transfer reactions match the measured data, suggesting good understanding of the processes taking place inside the gas mixture. As a proof of principle we demonstrate the method with a measurement of the 2
p
-1
s
muonic x rays from a 5
μ
g
gold target.
A correlation is established between thermodynamic data for hypothetical macroscopic amounts of elements and experimentally accessible data on gold surfaces. The correlation between the ...experimentally determined standard adsorption enthalpies of elements on gold surfaces and their standard sublimation enthalpies is shown to be valid over a broad data range for various elements from light noble gases (Kr) up to heavy metals (Pb, Bi). This type of correlation is indispensable to derive thermodynamic data for macroscopic amounts of elements from results of adsorption chromatographic experiments with single atom amounts. It is also necessary to predict the behavior of single atoms from given or estimated thermochemical data. The conditions under which this correlation is valid are elaborated. Finally, predicted data for the elements 112 and 114 are used to link them to the corresponding sublimation or adsorption data. The obtained prediction intervals are of exceptional importance for the design of sophisticated experimental setups for the chemical investigation of transactinide elements on a single atom scale.
The adsorption properties of Rn on polycrystalline surfaces of the transition metals Cu, Ag, Au, Ni, and Pd are investigated experimentally by vacuum thermochromatography. This experimental approach ...provides a fast separation of short-lived nuclides of volatile elements on clean metal surfaces. The adsorption enthalpies of Rn are quantified from the experimental results using a thermodynamic equilibrium model and a Monte Carlo based kinetic model of mobile adsorption, developed in this work. The experimentally observed strength of Rn adsorption is given by the sequence: Ni > Pd ≈ Cu > Au > Ag. The obtained adsorption data are compared with results from empirical calculations of the weak interaction of closed shell atoms with metallic surfaces. An empirical model, which was developed on the basis of experimental adsorption data of Ne, Ar, Kr, and Xe, is extended in order to calculate the adsorption enthalpies of Rn. An excellent agreement is found between model results and the experimental data for the adsorption of Rn on Ag, Au, Ni, and Pd. Extending the model furthermore to the hypothetically noble-gas such as super heavy elements 112 and 114, their adsorption enthalpies on Cu, Ag, Au, Ni, and Pd are predicted. The results and the experimental approach are discussed in view of the experimental investigation of gas-phase chemical properties of the transactinide elements 112 and 114.
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