71 research outputs found
The calibers of the common femoral, popliteal, and posterior tibialis arteries: a statistical investigation in 100 healthy subjects by color Doppler ultrasonography.
The original calibre of the lower limbs arteries as a possible risk factor for complications of atherosclerosis: a statistical investigation in 90 subjects by echocolor-doppler.
Room Temperature CO Detection by Hybrid Porphyrin-ZnO Nanoparticles
AbstractPorphyrins are the natural candidates to the detection of carbon monoxide however the physical properties of solid-state layers of porphyrins limit their use as gas sensors mainly with mass and optical transducers. Recently we shown that the photonic properties of porphyrins, brilliantly exploited in organic solar cells, can lead to a new class of photo-activated sensors made by porphyrins coated metal oxides. Here we investigate the sensitivity to carbon monoxide of resistive sensors made by zinc oxide nanoparticles coated by a porphyrin layer. Sensors were prepared following two different routes and tested, at room temperature and in various light conditions, to CO and few volatile compounds. Results show a significant sensitivity and selectivity to CO
Collateral circulation in occlusion of lower limbs arteries: an anatomical study and statistical research in 35 old subjects.
Magnetic resonance angiographic evaluation of circulus arteriosus cerebri (circle of Willis): a morphologic study in 100 human healthy subjects.
Collateral circulation in distal occlusion of lower limb arteries: an anatomical study and statistical research in 40 elderly subjects by echo-color-Doppler method.
Optimization of gas sensors measurements by dynamic headspace analysis supported by simultaneous direct injection mass spectrometry
Dynamic headspace extraction is frequently used in gas sensors measurements. The procedure may introduce artefacts but its influence in sensor signals interpretation is rarely considered. In this paper, taking advantage of the on-line combination of a quartz microbalance gas sensor array with a proton transfer reaction mass spectrometer, we have been able to track the evolution of the concentration of volatile compounds along 75 s of extraction of the headspace of differently treated tomato pastes. Proton transfer reaction mass spectrometer signals show that VOCs are characterized by a large diversity of the evolution of the concentration. VOCs kinetics has been described by an electric equivalent circuit model. On the other hand, sensor signals continuously grow approaching a steady value. The contrasting behaviour between sensors signals and the concentration of most of VOCs is explained considering that water is the dominant component in the tomato paste sample and that water is one of those compounds whose concentration in the sensor cell steadily grows. Analysis of variance show that sensors signals achieve the largest separation between classes when the concentration of VOCs in the sensor cell reached its peak. Thus, although the sensor signals continue to rise their information content decays. This finding suggests that measurement protocols need to be adjusted according to the properties of the sample and that the actual measurement times could be much shorter than those predicted from the behaviour of sensor signal
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