The results of the study of the thermodynamical parameters and the magnetic field in the solar photosphere during the solar microflare on 2009 July 4 in the active region NOAA 11024 are presented. ...The analysis is based on the observations with the French-Italian telescope THEMIS (Heliographic Telescope for the Study of the Magnetism and Instabilities on the Sun), operated on the island of Tenerife in the Spanish Observatorio del Teide of the Instituto de Astrofisica de Canarias in the multiline spectropolarimetric mode. The high-resolution Stokes I, Q, U and V profiles of 10 photospheric lines are used for the modelling. Semi-empirical models are derived from the inversion with Stokes Inversion based on Response functions code, developed by Ruiz Cobo and del Toro Iniesta. The models include two components: a thin magnetic flux tube and its non-magnetic surroundings. The temporal variations in all photospheric parameters are revealed during the microflare. The magnetic field strength increased from 800 to 1200 G during the onset phase of the microflare. The inferred flux tube models show the temperature enhancement in the photospheric layers relative to the quiet-Sun model atmosphere at the onset of the flare. The temperature inhomogeneities are found in the inferred atmosphere at the end of the microflare.
We studied the geochemistry of Paleoproterozoic siliceous rocks (lydites) from the North Onega synclinorium (Karelia). The study objects are represented by 16 lydite samples taken from one ...stratigraphic level in the geological sections of two sites–Tetyugino and Shunga. Their structural characteristics and mineral composition were studied using a scanning electron microscope equipped with an energy-dispersion microanalyzer. The trace element composition was determined by the inductively coupled plasma mass spectrometry (ICP-MS). The contents of most trace elements are below the Clarke concentrations. The Tetyugino lydites contain mainly biophile elements (P, Co, Cu, Mo, V, Ba), while the Shunga lydites are dominated by lithophile elements (Li, Rb, Cs). The trace element composition of lydites indicates that their formation took place on the periphery of the hydrothermal system, whereas the Tetyugino site was closer to the hydrothermal discharge zone than the Shunga site. The chemical peculiarities of the lydites allow us to consider them as a raw material for very pure quartz.
An actual problem today is the search for observed evidence of the existence of deep small-scale magnetic fields of the Sun. In this regard, the authors analyzed the theoretical criterion for ...separating the contributions to the solar surface magnetism of two qualitatively different mechanisms of a small-scale dynamo, the action of which is hidden in the depths of the solar convection zone (SCZ), proposed by Sokoloff and Khlystova Astron. Nachr. 2010. 331. P. 82–87. The first mechanism ensures the generation of small-scale magnetic fields due to the interaction of turbulent motions with the mean magnetic field (small-scale dynamo-1 of macroscopic MHD), while the second mechanism causes self-excitation of magnetic fluctuations due to turbulent pulsations of highly conductive plasma ( diffusive small-scale dynamo-2 of classical MHD). The essence of the proposed criterion is that deep small-scale magnetic fields can lead under certain conditions to violations of Hale’s and Joy’s laws of observed magnetism on the surface of the Sun. Statistical analysis of these disturbances allows one to identify the differences in the evolution of the observed manifestations of two sources of small-scale fields since the contribution of two deep dynamo mechanisms to surface magnetism varies with the phase of the solar cycle in different ways. Such an important feature is the behavior of the percentage of anti-Hail groups of sunspots (in relation to the total number of sunspots) during the cycles. In the case of small-scale dynamo-1, the percentage of anti-Hale groups is independent of cycle phase, whereas the percentage of anti-Hale groups associated with diffusive small-scale dynamo-2 should reach its maximum value at solar minima. Therefore, the variations of magnetic anomalies make it possible to separate the meager contributions of two small-scale dynamo mechanisms to surface magnetism. In this connection, the task of identifying the markers of a small-scale dynamo in the solar depths from observations becomes relevant. With this in mind, we conducted an analysis of literature data of statistical studies of long series of observed violations of Hale’s and Joy’s laws, which can be caused by the presence of deep small-scale magnetic fluctuations of various origins. In particular, it was demonstrated in the work of Sokoloff, Khlystova, and Abramenko Mon. Notic. Roy. Astron. Soc. 2015. 451. P. 1522–1527 on the basis of processing the data of different catalogs for the period 1917–2004 that the percentage of anti-Hale groups of spots increases during the minima of solar cycles. This testifies to the operation of a diffusive small-scale turbulent dynamo-2 within the SCZ, the efficiency of which becomes noticeable near the minima of the cycles, when the global toroidal magnetic field weakens. As a result of the authors' analysis of six magnetic active regions observed near the minima of the 24th and 25th solar cycles, characteristic violations of Hale’s and Joy’s laws were revealed, which may indicate the influence of a diffusive small-scale dynamo-2 on the evolution of these regions since it is this source that gives the most noticeable contribution in surface magnetism near cycles minima.
AgI-SiO
2
hybrid powders (HPs) based on SBA-15, MCM-41, and MCM-48 have been prepared by template co-condensation of silica and silver iodide under hydrothermal conditions. The effect of the Ag/Si ...ratio and the type of silica matrix on the textural, structural, morphological, and rheological properties of the HPs has been studied. The formation of the target phase of iodargyrite (β-AgI) is dependent both on the ratio of the main components Ag/Si and on the pore arrangement in the silica matrix, as detected by XRD. The small-angle XRD and low-temperature nitrogen adsorption data have shown the textural and structural properties of AgI-SiO
2
hybrid powders to be similar to the porous structure of the initial silica matrices—SBA-15, MCM-41, or MCM-48. A uniform distribution of silver iodide in all silica matrices, SBA-15, MCM-41 and MCM-48, has been demonstrated by energy dispersive microanalysis (EDAX). For AgI-SiO
2
powders with various types of pore arrangement, a high fluidity degree has been demonstrated using the data on the natural angle of repose. It has been shown that MCM-48 based β-AgI-SiO
2
powders are characterized by the smallest crystallite sizes (~6 nm), and average size of particles (50 nm) and average size of particle aggregates (13 μm), the highest specific surface area (up to 860 m
2
/g) and the best fluidity.
Graphical Abstract
Highlights
The formation of the target β-AgI phase, iodargyrite, in AgI-SiO
2
hybrid powders (HP) depends both on the component Ag/Si ratio and on the pore arrangement type of the silica matrix.
Crystal phase, corresponding to iodargyrite, was detected in HPs samples prepared using the Ag/Si ratios within the range from 0.04 to 0.08.
In AgI-SiO
2
powders prepared by hydrothermal template synthesis via а co-condensation route, the ordered pore arrangement was found to be similar to that of the initial silica matrices—SBA-15, MCM-41 or MCM-48.
The smallest crystallites (~6 nm), average size of particles (50 nm) and average size of particle aggregates (13 μm), the highest specific surface area (up to 860 m
2
/g), and the best fluidity was found in the case of β-AgI-SiO
2
powders based on the MCM-48 matrix.
The results of the analysis of the full Stokes profiles of the photospheric lines Fe I λ 630.15 nm and Fe I λ 630.25 nm in a region of chromospheric dual flows appearance in the vicinity of a small ...pore are presented. The analysis is based on the spectropolarimetric observations of the active region NOAA 11024 with the THEMIS French–Italian telescope (Tenerife Island, Spain). The temporal variations in the high-resolution Stokes parameters
I, Q, U
, and
V
were considered for each pixel. It was found that the dual chromospheric flows appeared in the region of the abnormal Stokes profiles of the photospheric lines. Most of the Stokes profiles
Q, U
, and
V
have a complex shape and vary greatly from pixel to pixel, which indicates strong inhomogeneities in the structure of the magnetic field in that region. The amplitude and shape of the Stokes profiles were rapidly changing during the observations. A change in the polarity of the photospheric magnetic field took place during the observations in the region of a bright chromospheric point. The evidence of the emergence of a new small-scale magnetic flux of the opposite polarity is obtained; this could lead to magnetic reconnections, appearance of dual chromospheric flows, and occurrence of a microflare.
The thermodynamic parameters and parameters of the photospheric magnetic field in the region of chromospheric dual flows in the vicinity of a small pore in the active region NOAA 11024 are presented. ...The dual chromospheric flows that appeared in the region of abnormal Stokes
V
profiles of the photospheric lines were associated with the emergence of a new small-scale magnetic flux of positive polarity. Semiempirical photospheric models were obtained by inversion using the SIR program (Stokes Inversion based on Response functions) 42. Each model contains two components: two thin magnetic flux tubes of different polarity. The magnetic flux has a negative polarity in the first component and positive in the second. The Stokes profiles of the photospheric lines Fe I λ 630.15, 630.25, and 630.35 nm and Ti I λ 630.38 nm from the spectropolarimetric observations with the French–Italian telescope THEMIS (Tenerife, Spain) were used for modeling. The altitudinal dependences of the temperature, line of sight velocity, inclination angle of the magnetic field vector, and azimuth angle in the tubes, as well as the values of the magnetic field strength and macroturbulent velocity, are obtained. The time variations in all parameters of the photosphere are revealed. The new magnetic flux emerged in the region of mixed polarities and was accompanied by the heating of the photosphere and chromosphere. The inferred flux tube models show the temperature enhancement by 400 K in the upper photospheric layers relative to the quiet-Sun model temperature. They indicate a complex, inhomogeneous small-scale structure of the magnetic field and the velocity field. The magnetic field strength in the tubes varies from 0.03 to 0.13 T during the period under consideration. The inclination angles of the magnetic field vector and the azimuth angles strongly differ in magnetic flux tubes and vary in time. The line-of-sight velocity does not exceed 2 km/s. The downflows in the lower layers of the photosphere and the upflows in the upper layers dominate in the first component of the models. In the second component of the model, the material in the upper photosphere is lifted. The macroturbulent velocity in most cases exceeds its value for the unperturbed photosphere. The velocity is greater in the second component of the models. The emergence of the new magnetic flux could lead to the magnetic reconnection and occurrence of a microflare.
—
We have synthesized silica-based sorbents with MCM-41 and MCM-48 pore structures, modified with hydrazide groups based on
tret
-carboxylic acids of Versatic 10 and Versatic 1519 fractions, and ...investigated textural and structural properties of the silicas. Conditions for tungsten(VI) sorption from acid solutions by the silicas have been studied in relation to the pH of the medium and grafting density, and conditions have been found for tungsten(VI) and molybdenum(VI) separation from hydrochloric acid solutions using MCM-41 modified silica.
—
We have studied the effect of the nature of the alkaline agent (NH
4
OH, NaOH, (NH
4
)
2
CO
3
, and Na
2
CO
3
) on the specific surface area, size, and shape of zinc oxide particles prepared via ...zinc nitrate precipitation from aqueous and polymer media, followed by thermal decomposition of the precipitates. The precipitation process with the use of NH
4
OH and NaOH in polyacrylamides has been shown to be favorable for the formation of large hexagon particles, which were larger (up to 1500 nm in size) in the case of NH
4
OH. The largest specific surface area (up to 98 m
2
/g) and the smallest particle size (~20 nm) were offered by the sample prepared via thermal decomposition of the products of reaction between zinc nitrate and ammonium carbonate.
The variations of the chromospheric line-of-sight velocity in the active region NOAA 11024 are studied before, during, and after a solar microflare on 2009 July 4. At the day of the observations the ...main emergence phase was in this active region. The new emerging flux has interacted with the pre-existing magnetic field.
The spectropolarimetric observations were carried out with the French–Italian THEMIS telescope (Spain, Tenerife). We used Hα spectra of the high resolution obtained over 21min. The spatial resolution was ∼1 arcsec. The time interval between the spectra was 2.84s. Doppler velocities were measured in the microflare location and its surroundings. We have revealed strong temporal variations of the line-of-sight velocity in the chromosphere. The velocities changed in the range −33–10km/s. We revealed the velocity oscillations with the amplitude of 4–5km/s. 12–14min before the microflare both upward and downward motions with velocity values reaching about 20km/s are found on the outer edge of the region studied. The amplitude of the oscillations increased. It may be the signature of the magnetic reconnection.
The rheological characteristics of struvite-based fire extinguishing powder mixtures are comparatively analyzed when using hydrophobic silicon dioxide as a functional filler, obtained during a ...single-stage synthesis by various methods. Infrared spectroscopy, scanning electron microscopy, low-temperature nitrogen sorption–desorption, and other methods are used to investigate the influence of the synthesis method on the textural and structural properties of hydrophobic functional fillers of fire extinguishing powder mixtures. It is revealed that the key factor affecting the rheological properties of such mixtures is the uniform distribution of the functional filler over the surface of the particles of a fire extinguishing component (struvite). It is proven that the struvite-based powder composition and the developed functional filler are highly effective for fire extinguishment.
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