[en] The works made during Sept 21 to Oct 05, 1989 for carrying out the topography, geophysical, geologic, radiometric and hydrological surveys are presented, allowing the characterization of a succession of parameters that are useful for geotechnical and hydrology works of the candidate sites for depositing the radioactive wastes. (C.G.C.)

[en] Ischemically injured reperfused myocardium is characterized by increased 18F-fluorodeoxyglucose uptake as demonstrated by positron emission tomography. To elucidate the metabolic fate of exogenous glucose entering reperfused myocardium, D-[6-14C] glucose and L-[U-13C] lactate were used to determine glucose uptake, glucose oxidation and the contribution of exogenous glucose to lactate production. The pathologic model under investigation consisted of a 3 h balloon occlusion of the left anterior descending coronary artery followed by 24 h of reperfusion in canine myocardium. The extent and severity of myocardial injury after the ischemia and reperfusion were assessed by histochemical evaluation (triphenyltetrazolium chloride and periodic acid-Schiff stains). Thirteen intervention and four control dogs were studied. The glucose uptake in the occluded/reperfused area was significantly enhanced compared with that in control dogs (0.40 +/- 0.14 versus 0.15 +/- 0.10 mumol/ml, respectively). In addition, a significantly greater portion of the glucose extracted immediately entered glycolysis in the intervention group (75%) than in the control dogs (33%). The activity of the nonoxidative glycolytic pathway was markedly increased in the ischemically injured reperfused area, as evidenced by the four times greater lactate release in this area compared with the control value. The dual carbon-labeled isotopes showed that 57% of the exogenous glucose entering glycolysis was being converted to lactate. Exogenous glucose contributed to greater than 90% of the observed lactate production. This finding was confirmed by the histochemical finding of sustained glycogen depletion in the occlusion/reperfusion area. The average area of glycogen depletion (37%) significantly exceeded the average area of necrosis

No abstract available

[en] Quantification of regional myocardial blood flow (MBF) with rubidium-82 (⁸²Rb) and positron emission tomography (PET) requires the validation of a tracer kinetic model that adequately describes the kinetics of ⁸²Rb in tissue. We performed 134 ⁸²Rb kinetic experiments in 24 isolated, arterially perfused rabbit interventricular septa at different flow rates (0.5-4.5 ml.min-1.g-1) and under the following conditions: varied concentrations of glucose (2.8-11 mM), insulin (0-5 mU/ml), and potassium (5-8 mM); varied pH (7.2-7.8); varied workload; and the addition of acetylstrophanthidin (1.0 microM). The measured ⁸²Rb tissue time-activity curves consisted of two exponential components, with half times inversely related to MBF. The size of the slow component decreased as MBF increased (from 70% at 0.3 ml.min-1.g-1 to 30% at 2.0 ml. min-1.g-1). The kinetics were not strongly dependent on the conditions studied and were consistent with a compartmental model containing two communicating compartments. The volume of the fast exchangeable compartment and the transport rate constant from the fast to the slow compartment were found to be independent of MBF. Values of MBF were estimated with the compartmental model from ⁸²Rb kinetics, and they correlated well with the directly measured MBF (r = 0.91; slope = 1.03)

[en] Au and Cu Nanocrystals (NCs) were fabricated using ion implantation into SiO2 and subsequent thermal annealing. Vibrational properties were studied using extended x-ray absorption fine structure (EXAFS) spectroscopy at measurement temperatures between 15 and 300 K. Einstein temperatures were extracted and show a significant decrease for 3.3 nm Cu NCs as compared to bulk Cu. Au NCs, however, show no significant change in the Einstein temperature even at a size of 2.5 nm. The influence of the competing processes of softening of the vibrational density of states due to under-coordinated surface atoms and stiffening of the NC core atoms due to surface tension effects are discussed

No abstract available

[en] The application and incorporation of residues as a precursor material for use as alkaline activated binders has been found in literature, for instance, coal ash, mining, ceramic, demolition and agro-industry wastes. The objective of this work is to present preliminary results obtained from experiments using ashes obtained from the calcination of sewage sludge to synthesize a geopolymer material for immobilization of radwastes. (author)

[en] Regional myocardial perfusion and glucose uptake were assessed with rubidium 82 (Rb), F-18-deoxyglucose (FDG) and positron emission tomography (PET) in patients with coronary artery disease and stable (SA) or unstable (UA) angina pectoris and in a group of normal subjects. In SA patients at rest, myocardial perfusion and glucose uptake were comparable to those in normal subjects. However, a regionally increased FDG uptake was observed in the SA patients during recovery from an episode of exercise-induced ischaemia, in the same regions as showed abnormal perfusion during the stress test. In UA patients, regional myocardial perfusion at rest was not significantly different from that in SA patients and normal subjects. Conversely, in all UA patients myocardial glucose utilization was significantly greater than in SA patients and normal subjects. This occurred in the absence of symptoms and electrocardiographic signs of acute ischaemia at the time of the study. A significant reduction of myocardial glucose utilization - which, however, remained higher than in SA patients and normal subjects - was observed in the UA patients who were restudied during i.v. infusion of nitrates. (orig.)

[en] Positron emission tomography was used to image blood flow and metabolic tracers in risk zone myocardium after left anterior descending coronary artery occlusion during synchronized coronary venous retroperfusion. Six control and seven intervention open chest dogs had occlusion of the mid left anterior descending coronary artery. Synchronized retroperfusion commenced 25 min later. Flow tracers (rubidium-82 and nitrogen-13 ammonia) were injected retrogradely. Three hours after coronary occlusion, fluorine-18 (F-18) deoxyglucose uptake in the control and treatment groups was compared. At 200 min of occlusion, infarct size was assessed. Retrograde flow tracer uptake was observed in the risk zone in the seven intervention dogs. Fluorine-18 deoxyglucose uptake in the risk zone was increased in five of the six intervention dogs but was reduced in five of the six control dogs. The risk zone to normal zone F-18 deoxyglucose count ratio was higher in the intervention than the control group (1.13 ± 0.39 vs. 0.59 ± 0.51; p less than 0.05). The endocardial subsegment risk zone to normal zone F-18 deoxyglucose count ratio was also significantly higher in the intervention group. Percent infarction in the risk zone was 70% lower in the group treated with synchronized retroperfusion than in the control group (18.4 ± 22.6% vs. 61.2 ± 25.4%; p less than 0.02). Thus, positron emission tomography revealed that retroperfusion could deliver oxygenated blood and maintain metabolism in risk zone myocardium. Infarct size was limited to 30% of that of control. In acute closure of the left anterior descending coronary artery, synchronized retroperfusion might be considered for maintaining viability of the jeopardized myocardium if the artery cannot be reopened rapidly

[en] The magnetization of the nanocomposite (Fe_1-xCo_x)_y(MnO)_1-y was investigated in the temperature (T) range 5-300 K and for applied magnetic fields (H) up to 2 T. The measurements were carried out in samples prepared by mechanical alloying with x = 0.4 and 0.6, and y = 0.35, 0.65 and 1. Room temperature Henkel plots indicated that the Fe_1-xCo_x nanoparticles interacts among each other predominantly through dipolar interaction. Furthermore, exchange-bias effect was observed for temperatures below the MnO Neel temperature (T_N = 117.7 K) with the corresponding exchange-bias field showing a significant increase with decreasing T. This trend was also followed by the coercive field. It was also observed below T_N an irreversible behaviour in the zero-field- and field-cooled magnetizations.