•An amorphous pure Ni films have been fabricated by using DC magnetron sputtering.•An amorphous Ni films are not ferromagnetically ordered at least at T>78K.•Optical conductivity spectrum of ...amorphous Ni films does not show absorption peaks.
The effect of the structural disorder in Ni films on their magnetic, magneto-optical (MO), transport, optical properties, and the spin polarization degree of conduction electrons as well as the electronic structure has been investigated. Room temperature (RT) DC magnetron sputtered onto glass substrates Ni films have been found to be amorphous. It was experimentally shown that an amorphous Ni films (i) are not ferromagnetically ordered at least for T>78K temperature range, (ii) do not show any MO response at RT, (iii) have 10 times larger resistivity than crystalline phase which nearly does not depend on temperature, (iv) exhibit the optical conductivity (OC) spectrum without interband absorption peaks typical for crystalline Ni, (v) have spin polarization degree of conduction electrons close to zero. Annealing of amorphous Ni films at T = 600 K causes their crystallization with the formation of the face-centered-cubic phase and restores the physical properties typical for crystalline Ni. The experimental OC spectrum of crystalline Ni film exhibits an intense interband absorption peaks located at E = 1.4 and 4.55 eV; it is in reasonable correspondence with the calculated interband OC spectrum of Ni. Main absorption peaks in the experimental OC spectrum were put in correspondence with the electron excitations between definite electronic states of the E(k) structure of Ni. The experimentally determined spin polarization degree of conduction electrons of crystalline Ni films was found to be close to that for bulk Ni and consists of P≈40%.
An algorithm for retrieving the fraction of the sea surface covered by whitecaps (W) from Landsat-8 satellite optical reflectance measurements in the near-infrared channel is described. The ...distribution of W derived from approximately 100 Landsat-8 scenes was compared with quasi-synchronous scatterometer measurements of wind speed (u10), which allowed us to obtain the W(u10) relation for large whitecaps from high-resolution satellite optical measurements. Further, we demonstrate the impact of various phenomena, including- internal waves, river plumes, bottom topography, atmospheric stability, ocean fronts, and mesoscale currents on whitecap coverage and its spatial variation in different areas of the ocean. These data are analysed using theoretical models, suggesting that whitecap coverage is a proxy of wave energy dissipation and reflects disturbances in the wind-wave energy balance caused by wave-current interactions and variable wind forcing due to changes in atmospheric stratification over ocean temperature fronts and the movement of wind-waves by surface currents relative to the atmospheric boundary layer.
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•Algorithm for retrieval of whitecaps coverage (W) from Landsat-8 is presented.•Scatterometry wind velocity (u10) and W are used to parameterize W(u10).•Various example of the impact of ocean and atmosphere dynamics on W is presented.•They include internal waves, river plumes, bottom topography, ocean fronts e.t.c.
The impact of ocean spray on the dynamics of the marine near-surface air boundary layer (MABL) in conditions of very high (hurricane) wind speeds is investigated. Toward this end, a model of the MABL ...in the presence of sea-spume droplets is developed. The model is based on the classical theory of the motion of suspended particles in a turbulent flow, where the mass concentration of droplets is not mandatory small. Description of the spume-droplet generation assumes that they, being torn off from breaking waves, are injected in the form of a jet of spray into the airflow at the altitude of breaking wave crests. The droplets affect the boundary-layer dynamics in two ways: via the direct impact of droplets on the airflow momentum forming the so-called spray force, and via the impact of droplets on the turbulent mixing through stratification. The latter is parametrized applying the Monin–Obukhov similarity theory. It is found that the dominant impact of droplets on the MABL dynamics appears through the action of the ‘spray force’ originated from the interaction of the ‘rain of spray’ with the wind velocity shear, while the efficiency of the stratification mechanism is weaker. The effect of spray leads to an increase in the wind velocity and suppression of the turbulent wind stress in the MABL. The key issue of the model is a proper description of the spume-droplet generation. It is shown that, after the spume-droplet generation is fitted to the observations, the MABL model is capable of reproducing the fundamental experimental finding—the suppression of the surface drag at very high wind speeds. We found that, at very high wind speeds, a thin part of the surface layer adjacent to the surface turns into regime of limited saturation with the spume droplets, resulting in the levelling off of the friction velocity and decrease of the drag coefficient as
being the wind speed at 10-m height.
Endothelial cells (ECs) line the blood vessels and lymphatic vessels, as well as heart chambers, forming the border between the tissues, on the one hand, and blood or lymph, on the other. Such a ...strategic position of the endothelium determines its most important functional role in the regulation of vascular tone, hemostasis, and inflammatory processes. The damaged endothelium can be both a cause and a consequence of many diseases. The state of the endothelium is indicated by the phenotype of these cells, represented mainly by (trans)membrane markers (surface antigens). This review defines endothelial markers, provides a list of them, and considers the mechanisms of their expression and the role of the endothelium in certain pathological conditions.
The radioactive element astatine exists only in trace amounts in nature. Its properties can therefore only be explored by study of the minute quantities of artificially produced isotopes or by ...performing theoretical calculations. One of the most important properties influencing the chemical behaviour is the energy required to remove one electron from the valence shell, referred to as the ionization potential. Here we use laser spectroscopy to probe the optical spectrum of astatine near the ionization threshold. The observed series of Rydberg states enabled the first determination of the ionization potential of the astatine atom, 9.31751(8) eV. New ab initio calculations are performed to support the experimental result. The measured value serves as a benchmark for quantum chemistry calculations of the properties of astatine as well as for the theoretical prediction of the ionization potential of superheavy element 117, the heaviest homologue of astatine.
The impact of new parametrizations for drag and air–sea enthalpy exchange on modelling the intensity of tropical cyclones with a numerical weather prediction (NWP) model is examined. These ...parametrizations follow from a model for the marine atmospheric boundary layer for high wind-speed conditions in the presence of spray droplets that originate from breaking wave crests. This model accounts for the direct impact of these droplets on the air–sea momentum flux through action of a
spray force
, which originates from the interaction of the ‘rain’ of spray droplets with the vertical wind shear and is expressed in terms of the spray generation function (SGF). The SGF is cubic in the wind speed up to 50 m s
-
1
beyond which its value increases less strongly. The drag coefficient (
C
D
) decreases from a wind speed of approximately 30 m s
-
1
, in agreement with the available measurements in these conditions. The enthalpy exchange coefficient (
C
k
) increases with increasing wind speed and slowly decreases beyond a wind speed of about 40 m s
-
1
due to the strong decrease in
C
D
. The value for
C
k
/
C
D
is in agreement with observational data for wind speeds up to 30 m s
-
1
; for higher wind speeds the value is in the range 1.2–1.5 in agreement with a well-established theory. The parametrization is tested in an NWP model. The tropical cyclones Ivan (2004) and Katrina (2005) in the Gulf of Mexico are simulated. To the sea surface temperatures (SSTs) from the European Centre archive that were prescribed to the NWP model, a parametrized cooling (based on estimations from theoretical studies and measurements) was applied during the model forecasts, as the NWP model does not resolve locally rather strong induced reductions in SSTs. The simulations show that realistic tropical cyclone wind speeds and central pressure can be obtained with the proposed drag and enthalpy parametrizations. The results indicate that the value for
C
k
/
C
D
at very high wind speeds is in the correct range. Moreover, the results motivate the application of the parametrizations in atmosphere–ocean coupled models.
We studied the effect of different doses of ammonium chloride (ACl) and ammonium carbonate (ACr) on immunological parameters of the peripheral blood in rats during high-intensity exercise. Changes in ...the absolute and relative numbers of granulocytes, lymphocytes, natural killers, naive and mature effector cells one day after the end of the forced swimming cycle were found by using a hematological analyzer and a flow cytometer. Immunological indicators were analyzed relative to swimming duration on the last day of ultimate load. The revealed changes indicate the onset of the effector phase of the development of the inflammatory processes in the positive control group (physiological saline) and in rats receiving a higher dose of ACr (20 mg/kg), while administration of ACl prevented the development of inflammatory processes and shifts in the physiological balance of lymphocyte subpopulations. Immunological profiling indicates that ACl in a dose of 20 mg/kg most effectively improved physical performance in our forced swimming model.
Satellite monitoring systems in forestry Zhichkina, L N; Nosov, V V; Zhichkin, K A ...
Journal of physics. Conference series,
04/2020, Volume:
1515, Issue:
3
Journal Article
Peer reviewed
Open access
Space technologies in Earth remote sensing are among the most relevant technologies for monitoring forestry. Difficulties of controlling tree felling and other activities by forestry employees ...constitute an objective problem which can only be solved by application of space monitoring instruments. The article shows that using the LandViewer Software would provide regional forestry a wealth of information needed for ongoing work and detection of violations. The considered examples demonstrate that space monitoring provides a more accurate determination of the size of forest blocks and the felling volume.
A measurement is presented of the neutron production rate in lead by high energy cosmic-ray muons at a depth of 2850m water equivalent (w.e.) and a mean muon energy of 260GeV. The measurement ...exploits the delayed coincidences between muons and the radiative capture of induced neutrons in a highly segmented tonne scale plastic scintillator detector. Detailed Monte Carlo simulations reproduce well the measured capture times and multiplicities and, within the dynamic range of the instrumentation, the spectrum of energy deposits. By comparing measurements with simulations of neutron capture rates a neutron yield in lead of (5.78-0.28+0.21) ×10-3neutrons/muon/(g/cm2) has been obtained. Absolute agreement between simulation and data is of order 25%. Consequences for deep underground rare event searches are discussed.
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