Long-term radiocarbon variation studies in the air and tree rings of Slovakia.

Fifty-five years of radiocarbon variation studies are reviewed with an emphasis on a better understanding of the impacts of the Bohunice nuclear power plant and fossil fuel CO2 on the atmosphere and biosphere of Slovakia. The maximum Δ14C levels in the air up to about 1200‰ were observed during the 1970s at the Zlkovce monitoring station, which after 2005 decreased to <30‰. A relative decrease in the atmospheric Δ14C levels due to increasing levels of fossil CO2 in the atmosphere has also been significant, for example, in Bratislava down to about -330‰, but after 2005 they were only <50‰ below the Jungfraujoch European clean-air level. The tree-ring data, averaging the annual Δ14C levels for several stations in Slovakia, have been in agreement with the atmospheric data, as well as with the newly established clean-air station at Jasná in central Slovakia. Future 14C levels will depend strongly on fossil CO2 levels in the atmosphere, which will change the bomb 14C era to the fossil CO2 era. New investigations of 14C variations in the atmosphere-biosphere-hydrosphere compartments represent a great challenge for radiocarbon science, important for better understanding of environmental processes, climate change, and impacts of human activities on the total environment. This new era of radiocarbon research will also need new developments in radiocarbon analytical technologies, as further progress in accuracy and precision of results (<1‰) will be needed to meet the new radiocarbon challenges.

Tritium and radiocarbon in the water column of the Red Sea.

Despite being the busiest transient sea in the world due to the Suez Canal, radionuclide distribution studies in seawater and sediment of the Red Sea remain rare. A sampling expedition in the Red Sea was conducted from June 9 to July 6, 2021, visiting a transect of several deep sampling stations located along the central axis of the basin from the Gulf of Aqaba to the southern Red Sea (near Farasan Island, Saudi Arabia). The collected seawater profile samples were analyzed for tritium, radiocarbon and oxygen-18. The observed tritium levels in surface waters of the Red Sea peaked at 0.3-0.4 TU, similar to the values observed in the western Arabian Sea (decay corrected). The values observed at waters below 150 m were around 0.2 TU, however, at depths of 450 and 750 m, tritium minima (<0.2 TU) were observed, which could be associated with a partial return flow of bottom waters from the southern to the northern Red Sea. At two stations at the depth of about 550 m, deep Δ14C minima were observed as well (-4‰ and -10‰), documenting ongoing transport of carbon in the water column, important for sink of anthropogenic carbon.

Geant4-based electromagnetic background model for the CRESST dark matter experiment.

The CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) dark matter search experiment aims for the detection of dark matter particles via elastic scattering off nuclei in CaWO 4 crystals. To understand the CRESST electromagnetic background due to the bulk contamination in the employed materials, a model based on Monte Carlo simulations was developed using the Geant4 simulation toolkit. The results of the simulation are applied to the TUM40 detector module of CRESST-II phase 2. We are able to explain up to ( 68 ± 16 ) % of the electromagnetic background in the energy range between 1 and 40 keV .

Carbon and Pu isotopes in Baltic Sea sediments.

Distributions of 137Cs, 239,240Pu, Δ14C and δ13C measured in sediments indicated low 137Cs and 239,240Pu activities in the Curonian Lagoon and higher levels in the open Baltic Sea. Depleted δ13CTOC values were found in the Curonian Lagoon as compared with the open Baltic Sea, while the most depleted Δ14CTOC values were found in the Gotland Deep. The global fallout Pu dominated in the deeper zones of the Baltic Sea, while higher 240Pu/239Pu atom ratios were characteristic of the coastal regions.

Radiocarbon concentration in tree-ring samples collected in the south-west Slovakia (1974-2013).

Radiocarbon measurements of tree-ring samples collected in Vysoká pri Morave were compared with tree-ring data of the Zlkovce monitoring station situated 5km south-east from the Jaslovské Bohunice Nuclear Power Plant (NPP). Radiocarbon concentrations in Vysoká pri Morave and in Zlkovce tree rings were decreasing exponentially with decay constants of 14.48±1.23 y and 17.96±1.97 y, respectively, in agreement with similar results obtained at other radiocarbon stations. The Suess effect, represented by a dilution in 14C levels by fossil fuel CO2 emissions, was observed in both tree-ring data sets. The Vysoká pri Morave 14C data were during 1974-1995 systematically lower by about 50‰ than the Schauinsland (Germany) clean air reference values due to a regional fossil-fuel impact. However, after 1996 the Vysoká pri Morave 14C data were closer to the Schauinsland data due to lower CO2 emissions as a result of closing some of the heavy industry technologies in the region.

Impact of the Fukushima accident on tritium, radiocarbon and radiocesium levels in seawater of the western North Pacific Ocean: A comparison with pre-Fukushima situation.

Tritium, radiocarbon and radiocesium concentrations in water column samples in coastal waters offshore Fukushima and in the western North Pacific Ocean collected in 2011-2012 during the Ka'imikai-o-Kanaloa (KoK) cruise are compared with other published results. The highest levels in surface seawater were observed for 134Cs and 137Cs in seawater samples collected offshore Fukushima (up to 1.1 Bq L-1), which represent an increase by about three orders of magnitude when compared with the pre-Fukushima concentration. Tritium levels were much lower (up to 0.15 Bq L-1), representing an increase by about a factor of 6. The impact on the radiocarbon distribution was measurable, but the observed levels were only by about 9% above the global fallout background. The 137Cs (and similarly 134Cs) inventory in the water column of the investigated western North Pacific region was (2.7 ± 0.4) PBq, while for 3H it was only (0.3 ± 0.2) PBq. Direct releases of highly contaminated water from the damaged Fukushima NPP, as well as dry and wet depositions of these radionuclides over the western North Pacific considerably changed their distribution patterns in seawater. Presently we can distinguish Fukushima labeled waters from global fallout background thanks to short-lived 134Cs. However, in the long-term perspective when 134Cs will decay, new distribution patterns of 3H, 14C and 137Cs in the Pacific Ocean should be established for future oceanographic and climate change studies in the Pacific Ocean.

Kinetics and mechanism of the oxygenation of potassium flavonolate. Evidence for an electron transfer mechanism.

The oxygenation of the potassium salt of flavonol (flaH) in absolute DMF leads to potassium O-benzoylsalicylate and carbon monoxide in 95% yield at 40 degrees C. Kinetic measurements resulted in the rate law -d[flaK]/dt = k(2)[flaK][O(2)]. The rate constant, activation enthalpy, and entropy at 313.16 K are as follows: k(2)/M(-)(1) s(-1) = (3.28 +/- 0.10) x 10(-1), DeltaH()/kJ mol(-1) = 29 +/- 2, DeltaS/J mol(-1) K(-1) = -161 +/- 6. The reaction fits a Hammett linear free energy relationship for 4'-substituted flavonols, and electron-releasing groups make the oxygenation reaction faster. The anodic oxidation wave potentials E(a) of the 4'-substituted flavonolates correlate well with reaction rates. At more negative E(a) values faster reaction rates were observed. EPR spectrum of the reaction mixture (g = 2.0038, dH = 1.8 G, a(H) = 0.9 G) showed the presence of flavonoxyl radical as a result of a SET from the flavonolate to dioxygen.

Preparation and oxygenation of (flavonolato)copper isoindoline complexes with relevance to quercetin dioxygenase.

Mesitylcopper reacts with flavonol (flaH) in the presence of 1,3-bis(2-pyridylimino)isoindoline (indH) to yield the diamagnetic complex CuI(fla)(indH), which on reaction with molecular oxygen undergoes oxidative splitting of the C2-C3 bond of the pyranone ring of the flavonolate ligand to give CuI(indH)(O-bs) (O-bs = O-benzoylsalicylate) (orthorhombic, P1, a = 8.048(7) A, b = 8.969(9) A, c = 19.240(2) A, alpha = 85.69 degrees, beta = 80.24(7) degrees, gamma = 77.87(7) degrees, V = 1337(2) A3, Z = 2) and carbon monoxide. The reaction of [CuI(CH3CN)4]ClO4, flaH, and indH with dioxygen at room temperature affords the paramagnetic complex [CuII(fla)(indH)]ClO4 (mu = 2.10 mu B), and after elimination of HClO4, CuII(fla)(ind) (orthorhombic, Pbca, a = 8.888(2) A, b = 19.169(7) A, c = 33.614(10) A, alpha = beta = gamma = 90 degrees, V = 5727(3) A3, Z = 8) with mu = 1.86 mu B is formed. The latter undergoes cleavage of the pyranone ring on oxygenation at 80 degrees C to give CuII(ind)(O-bs) (mu = 1.87 mu B, nu(CO) = 1742 cm-1, and nu(CO2) = 1581, 1387 cm-1) and carbon monoxide. CuII(fla)(ind) and [CuII(fla)(indH)]ClO4 serve as good catalysts for the oxygenation of flavonol to O-benzoylsalicyclic acid.

Initial treatment of patients with acute ischemic heart disease hospitalized in a community hospital.

During the 1980s, tremendous advances occurred in understanding the pathophysiology of ischemic heart disease. Numerous clinical trials were performed to help clinicians formulate treatment plans and diagnostic schemes to care for patients with coronary artery disease. To see how these studies affect the evaluation and treatment of patients with acute coronary syndromes today, we reviewed the hospital records of patients admitted to our community hospital during September 1990. We found that such patients generally have a good short-term prognosis. Most can be stabilized using modern medical means, and in-hospital mortality is low. Antithrombotic and antianginal therapies are used liberally. Thrombolytic therapy is administered commonly, even to elderly patients. Invasive and noninvasive diagnostic testing procedures are both used frequently, and most acute myocardial infarction and unstable angina patients undergo revascularization.

Coronary angioplasty using new 6 French guiding catheters.

Coronary angioplasty (PTCA) was performed with specially constructed 6-French guiding catheters with an internal lumen of 0.051 inches. In 154 patients these guiding catheters were used in a variety of configurations in conjunction with miniature balloon-on-a-wire dilatation catheters in 1.5 to 3.5 mm sizes to perform PTCA. Overall patient success was 94%. PTCA was attempted in 24 totally occluded arteries with a success rate of 83% and 174 stenoses with a success rate of 97%. 6 French guiding catheters can be used to successfully perform PTCA.

Randomized comparison of over-the-wire and fixed-wire balloon devices for coronary angioplasty.

One hundred and fifteen consecutive patients undergoing coronary angioplasty (PTCA) were randomized to low profile over-the-wire (OTW, e.g., Mini, Sulp II) or fixed-wire (FW, e.g., Ace, Orion, Probe) PTCA balloon wire devices. Overall success, ability to begin and finish with the same balloon device, fluoroscopy time, physician time, and amount of contrast media used were prospectively assessed. Overall final success rate was excellent regardless of which type of system was used first (OTW 92%; FW 96%). In 6 patients no wire would cross, in another, the stenosis would not dilate despite high pressure ( greater than 18 atm). When an OTW device was used first, it was initially successful in 69% of patients and was changed with success to a second OTW balloon in 4 (cumulative 76%). An OTW balloon was changed to FW in 11 patients (success 9 patients, 82%). This was because of inability to cross with balloon of the OTW system after a steerable wire had crossed in 9 of the patients. When a FW device was used first, it was initially successful in 89%. A change to another FW device led to success in 4 additional patients (cumulative 96%). In no patient was a FW changed to an OTW device. Thus, a FW device was more likely to be successful (either 54 of 56 patients initially randomized to FW, or 63 of 67 total patient number in whom a FW device was used) than an OTW device (45 of 59 patients) p less than .05.(ABSTRACT TRUNCATED AT 250 WORDS)