1,020 research outputs found

    Application of 137 Cs for measuring soil erosion/deposition rates in Romania

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    Two methods of monitoring soil redistribution along agroterraces were explored in Tarina basin of the Moldavian Plateau: the classical method of annual or periodic field measurements and the 137C technique. Results obtained by both methods indicate that the aggradation rate of the agroterrace edge averages 5.0-6.0 cm/yr, but the 137C technique is more efficient because it requires only one field visit. Much of the dow n ward movement of soil in these agroterraces can be related to contour ploughing, although some erosion/deposition undoubtedly occurs. The future of using 137C as a tracer of erosion and sedimentation within discontinuous gullies is promising. Some results obtained in the Moldavian Plateau near Barlad support this assumption. A field study, based on a depth - incremental sampling method, was undertaken in two small basins, Roscani and Timbru. Depth distribution of 137Cs from recent sediments deposited along the floor of dis-continuous gullies allowed the establishment of a mean sedimentation rate of 4.4 cm/yr over the period 1963-1996, and 2.5 cm/yr after 1986 for short gullies. In the case of long gullies, after the Chernobyl nuclear accident this value is to 4.9 cm/year. Furthermore, it was possible to estimate: the age of the gullies (23-48 years), the mean gully head advance (0.9 m/yr), the mean total mass of sediment deposited/ eroded within the gully system (up to 124 t/yr) and the main sediment source (the active gully head and banks). Conservation practices and tillage were first implemented during 1982-1983 in the upper Racatau basin of 3,912 hectares. Significant changes in land management practices resulted from the application of the Landed Property Law no.18/1991. The marked shifting from contour to up and down hill farming created a doubling in the amount of soil erosion and deposition. Depth distribution of 137Cs in recent sediments of the Bibiresti reservoir indicates a mean sedimentation rate of 5.0 cm/yr over the period 1986-1992 and 10.0 cm/yr for the period 1993-1996

    Assessment of the reservoir sedimentation rates from 137 Cs measurements in the Moldavian Plateau

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    Reservoir sedimentation has been recognized as an important environmental threat in the Moldavian Plateau of Eastern Romania. Measurements of the 137Cs content of reservoir and, sometimes, floodplain sediments have been used to estimate the rate of sedimentation over the past 13-36 years . The estimated mean sediment accumulation rates in the reservoirs from three geomorphological subunits vary between 2.6 and 7.9 cm/year with an average rate of 4.6 cm/year after April 1986. Strong relationships were established between the individual sedimentation rates and the drainage area within the southern and central part of the Moldavian Plateau. The shape of the 137Cs depth profile was used as the main approach. Taking into account that the standard pattern is in the form of a cantilever and based on burial magnitude of 137Cs peak derived from Chernobyl two chief patterns of reservoir sedimentation were identified, shallow and deep buried cantilever, respectively

    Assessment of the reservoir sedimentation rates from 137 Cs measurements in the Moldavian Plateau

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    Reservoir sedimentation has been recognized as an important environmental threat in the Moldavian Plateau of Eastern Romania. Measurements of the 137Cs content of reservoir and, sometimes, floodplain sediments have been used to estimate the rate of sedimentation over the past 13-36 years . The estimated mean sediment accumulation rates in the reservoirs from three geomorphological subunits vary between 2.6 and 7.9 cm/year with an average rate of 4.6 cm/year after April 1986. Strong relationships were established between the individual sedimentation rates and the drainage area within the southern and central part of the Moldavian Plateau. The shape of the 137Cs depth profile was used as the main approach. Taking into account that the standard pattern is in the form of a cantilever and based on burial magnitude of 137Cs peak derived from Chernobyl two chief patterns of reservoir sedimentation were identified, shallow and deep buried cantilever, respectively

    Elaboration and characterization of the electrodeposited phosphates masses doped with various ions on stainless steel

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    The present paper is focused on elaboration of phosphate masses with good molar ratios on SS 316L, with fluoride, Zn2+ and Cu2+ as dopant ions, using an electrochemical procedure and also the attempt to select the best conditions for stainless steel. The surface was characterized using X-ray difraction, AFM and contact angle measurements. X-ray has evidenced crystaline phases, contact angle measurements has established the balance hydrophyl-hydrophob and AFM established roughness values. The inductively coupled spectrometry (ICP-MS) has quantified the amount of cooper and zinc ions released. In order to be used in biomedical applications hemolysis and antibacterial tests have been performed.Fil: Totea, G.. Faculty of Applied Chemistry and Materials Science; RumaniaFil: Ionita, D.. Faculty of Applied Chemistry and Materials Science; RumaniaFil: Katunar, Maria Rosa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación En Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: Cere, Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación En Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: Demetrescu, I.. Faculty of Applied Chemistry and Materials Science; Rumani

    Strongly interacting 2D electron systems: Evidence for enhanced 1D edge-channel coupling

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    We observe nearly vanishing Hall resistances for integer filling factors in a counterflow (CF) experiment on a density balanced 2D bilayer system. Filling factor dependent equilibration lengths demonstrate enhanced 1D coupling via edge-channels. Due to the narrow barrier the edge-modes of the two 2DEGs are in close proximity allowing for 1D excitonic correlations. Electron drag measurements confirm the observed quantum state selective coupling between the layers

    Ferritin is secreted via 2 distinct nonclassical vesicular pathways

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    Ferritin turnover plays a major role in tissue iron homeostasis, and ferritin malfunction is associated with impaired iron homeostasis and neurodegenerative diseases. In most eukaryotes, ferritin is considered an intracellular protein that stores iron in a nontoxic and bioavailable form. In insects, ferritin is a classically secreted protein and plays a major role in systemic iron distribution. Mammalian ferritin lacks the signal peptide for classical endoplasmic reticulum–Golgi secretion but is found in serum and is secreted via a nonclassical lysosomal secretion pathway. This study applied bioinformatics and biochemical tools, alongside a protein trafficking mouse models, to characterize the mechanisms of ferritin secretion. Ferritin trafficking via the classical secretion pathway was ruled out, and a 2:1 distribution of intracellular ferritin between membrane-bound compartments and the cytosol was observed, suggesting a role for ferritin in the vesicular compartments of the cell. Focusing on nonclassical secretion, we analyzed mouse models of impaired endolysosomal trafficking and found that ferritin secretion was decreased by a BLOC-1 mutation but increased by BLOC-2, BLOC-3, and Rab27A mutations of the cellular trafficking machinery, suggesting multiple export routes. A 13-amino-acid motif unique to ferritins that lack the secretion signal peptide was identified on the BC-loop of both subunits and plays a role in the regulation of ferritin secretion. Finally, we provide evidence that secretion of iron-rich ferritin was mediated via the multivesicular body–exosome pathway. These results enhance our understanding of the mechanism of ferritin secretion, which is an important piece in the puzzle of tissue iron homeostasis

    Evaluation of a Second-Generation Self- Expanding Variable-Porosity Flow Diverter in a Rabbit Elastase Aneurysm Model

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    BACKGROUND AND PURPOSE: The self-expanding V-POD is a second-generation flow-diverting device with a low-porosity PTFE patch on a self-expanding microstent. The authors evaluated this device for the treatment of elastase-induced aneurysms in rabbits
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