Search results for "dam"
showing 10 items of 3828 documents
Thermal annealing of radiation damage produced by swift 132Xe ions in MgO single crystals
2020
Abstract The annealing kinetics of the electron-type F+ and F color centers in highly pure MgO single crystals irradiated by 0.23-GeV 132Xe ions with fluences covering three orders of magnitude (Φ = 5 × 1011 –3.3 × 1014 ions/cm2) are studied experimentally via dependence of the optical absorption on preheating temperature. The annealing data are analyzed in terms of the diffusion-controlled bimolecular reactions between F-type centers and complementary interstitial oxygen ions. The behavior of the main kinetic parameters – the migration energies and pre-exponential factors – for different irradiation fluences is discussed and compared with that for other wide-gap binary materials from previ…
The peculiarities of the radiation damage accumulation kinetics in the case of defect complex formation
2020
Abstract The kinetics of radiation defect accumulation under irradiation by heavy particles is theoretically analysed under the assumption of defect complex genesis, particularly, the ones of anion and cation vacancies. The obtained analytical mathematical model and revealed peculiarities of radiation dose dependencies can be used for analysis of the experimental results for different crystalline materials for solid-state electronics and photonics.
Structural Tuning and Conformational Stability of Aromatic Oligoamide Foldamers
2017
A series of aromatic oligoamide foldamers with two or three pyridine-2,6-dicarboxamide units as their main folding motifs and varying aromatic building blocks as linkers have been synthetized to study the effects of the structural variation on the folding properties and conformational stability. Crystallographic studies showed that in the solid state the central linker unit either elongates the helices and more open S-shaped conformations, compresses the helices to more compact conformations or acts as a rigid spacer separating the pyridine-2,6-dicarboxamide units, which for their part add the predictability of the conformational properties. Multidimensional NMR studies showed that, even in…
Formation of dibutyl carbonate and butylcarbamate via CO2 insertion in titanium(IV) butoxide and reaction with n-butylamine
2016
Abstract The species resulting from insertion of 12CO2 and 13CO2 into titanium(IV) butoxide is for the first time fully characterized by means of infrared and nuclear magnetic resonance spectroscopy. Results show formation of Ti-monobutylcarbonate, that easily undergoes nucleophilic attack by an aliphatic amine. The hydrolysis of the resulting species produces butylcarbamate and dibutylcarbonate as the only main products. Characterization results of the carbonate-like adduct, along with its reactivity with amine molecules open the route to new ways of CO2 utilization as building block for valuable organic compounds.
One-Pot, Clean Synthesis of Vanillic Acid from Ferulic Acid
2016
Ferulic acid dissolved in water is selectively oxidized to vanillic acid in high yield (≈60 %) under remarkably mild and green conditions, namely at room temperature with air as primary oxidant, over a catalytic amount of nanostructured Bi2WO6. The process is general and opens the route to the selective oxidation of natural substances into derivatives of significant applicative relevance.
Reactions in the presence of irradiated semiconductors: Are they simply photocatalytic?
2018
A generally accepted classification distinguishes semiconductor photocatalysis in type A and type B. The first class comprehends reactions where the primary redox products (radical anions and cations) further evolve giving rise to the final reduced and oxidized species. Type B reactions occur when the primary redox products undergo intermolecular bond formation to addition products. Recently, some photocatalytic reactions have been reported wherein the photocatalytically produced compounds are not the final products. In fact, they react in the solution bulk or catalytically on the surface of the semiconductor with other species thus producing the target compounds. These reactions, hereby re…
Study of a sample of faint Be stars in the exofield of CoRoT
2013
International audience; Context. Be stars are probably the most rapid rotators among stars in the main sequence (MS) and, as such, are excellent candidates to study the incidence of the rotation on the characteristics of their non-radial pulsations, as well as on their internal structure. Pulsations are also thought to be possible mechanisms that help the mass ejection needed to build up the circumstellar disks of Be stars.Aims. The purpose of this paper is to identify a number of faint Be stars observed with the CoRoT satellite and to determine their fundamental parameters, which will enable us to study their pulsation properties as a function of the location in the HR diagram and to searc…
Effects of natural radiation damage on back-scattered electron images of single crystals of minerals
2006
Generally, it has been assumed that signal intensity variations in back-scattered electron (BSE) images of minerals are mainly controlled by chemical heterogeneity. This is especially true for images of single crystals, where effects of different crystal orientations with respect to the incident beam on the observed BSE are excluded. In contrast, we show that local variations of the structural state within single-crystals (i.e., degree of lattice order or lattice imperfectness) may also have dramatic effects on the back-scattering of electrons. As an example, we present BSE images of single-crystals of natural zircon, ZrSiO 4 , whose intensity patterns are predominantly controlled by struct…
Toward a Comprehensive Dam Monitoring: On-Site and Remote-Retrieved Forcing Factors and Resulting Displacements (GNSS and PS–InSAR)
2021
Many factors can influence the displacements of a dam, including water level variability and environmental temperatures, in addition to the dam composition. In this work, optical-based classification, thermal diachronic analysis, and a quasi-PS (Persistent Scatter) Interferometric SAR technique have been applied to determine both forcing factors and resulting displacements of the crest of the Castello dam (South Italy) over a one-year time period. The dataset includes Sentinel-1A images acquired in Interferometric Wide swath mode using the Terrain Observation with Progressive Scans SAR (TOPSAR); Landsat 8 Thermal Infrared Sensor (TIRS) thermal images, and Global Navigation Satellite System …
Humusica 2, article 19: Techno humus systems and global change - Conservation agriculture and 4/1000 proposal
2018
International audience; Philosophy can overlap pedology. It is not casual that life begins and finishes in the soil. We separated the concepts of Humipedon, Copedon and Lithopedon. Some sections were dedicated to the founders of the movement for a new type of agriculture (agroecology). They simply proclaim to accompany the process of natural evolution instead of spending a lot of energy in hunting competitor organisms with pesticides or boosting the soil with mineral fertilisation and tillage. The core of the article is built on a biological concept of the soil and shows researches supporting this view. After pointing to the soil structure and illustrating its natural genesis, explaining wh…