The taxonomic composition, abundance, and diversity of bacterial and fungal communities in the rhizosphere loci and bulk mass of the gray forest soil (Eutric Retisol (Loamic, Aric, Cutanic, Humic)) ...under potatoes, maize, and white mustard grown with the application of mineral and organic fertilizers were compared. Among bacteria,
Bacillus megaterium
and
Paenibacillus polymyxa
species predominated in all the experimental variants. The micromycete community was represented by 39 species belonging to 19 genera. Under the impact of organic fertilizers, the abundance of
Trichoderma harzianum—
an antagonist of many phytopathogens—increased. A decrease in the abundance of representatives of
Fusarium
genus was observed both in the rhizosphere and in the bulk soil. Fertilization was the most significant factor determining the structure and diversity of micromycete communities both in the soil and rhizosphere. The application of mineral fertilizers reduced the diversity of micromycetes in soil, whereas the use of organic fertilizers increased it. In general, organic fertilizers proved to be more favorable for the rhizosphere and bulk soil mycobiomes and for the total soil suppressiveness than the mineral fertilizers.
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Context.
Clouds are ubiquitous in exoplanet atmospheres and they represent a challenge for the model interpretation of their spectra. When generating a large number of model spectra, complex cloud ...models often prove too costly numerically, whereas more efficient models may be overly simplified.
Aims.
We aim to constrain the atmospheric properties of the directly imaged planet HR 8799e with a free retrieval approach.
Methods.
We used our radiative transfer code petitRADTRANS for generating the spectra, which we coupled to the PyMultiNest tool. We added the effect of multiple scattering which is important for treating clouds. Two cloud model parameterizations are tested: the first incorporates the mixing and settling of condensates, the second simply parameterizes the functional form of the opacity.
Results.
In mock retrievals, using an inadequate cloud model may result in atmospheres that are more isothermal and less cloudy than the input. Applying our framework on observations of HR 8799e made with the GPI, SPHERE, and GRAVITY, we find a cloudy atmosphere governed by disequilibrium chemistry, confirming previous analyses. We retrieve that C/O = 0.60
−0.08
+0.07
. Other models have not yet produced a well constrained C/O value for this planet. The retrieved C/O values of both cloud models are consistent, while leading to different atmospheric structures: either cloudy or more isothermal and less cloudy. Fitting the observations with the self-consistent Exo-REM model leads to comparable results, without constraining C/O.
Conclusions.
With data from the most sensitive instruments, retrieval analyses of directly imaged planets are possible. The inferred C/O ratio of HR 8799e is independent of the cloud model and thus appears to be a robust. This C/O is consistent with stellar, which could indicate that the HR 8799e formed outside the CO
2
or CO iceline. As it is the innermost planet of the system, this constraint could apply to all HR 8799 planets.
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•The M(H) magnetization curves of NiO nanoparticles (NPs) measured in pulsed fields of up to 250 kOe have been studied.•A model of NiO NP obtained from analysis of M(H) data have been ...proposed.•Surface and size effects as well as the origin and the magnitude of uncompensated magnetic moment have been revealed.
-The analysis of the M(H) magnetization curves of antiferromagnetic nanoparticles yields information about magnetic subsystems formed in these objects, which are characterized by a large fraction of surface atoms. However, in the conventionally investigated experimental magnetic field range of up to 60–90 kOe, this analysis often faces the ambiguity of distinguishing the Langevin function-simulated contribution of uncompensated magnetic moments μun of particles against the background of a linear-in-field dependence (the antiferromagnetic susceptibility and other contributions). Here, this problem has been solved using a pulsed technique, which makes it possible to significantly broaden the range of external fields in which the μun contribution approaches the saturation. Nanoparticles of a typical NiO antiferromagnet with an average size of ~ 4.5 nm have been investigated. Based on the thorough examination of the M(H) magnetization curves measured in pulsed fields of up to 250 kOe, a model of the magnetic state of NiO nanoparticles of such a small size has been proposed. The average moment is ~130 μB (μB is the Bohr magneton) per particle, which corresponds to 60–70 decompensated spins of nickel atoms localized, according to the Néel hypothesis (μun~ 3/2), both on the surface and in the bulk of a particle. A part of the surface spins unrelated to the antiferromagnetic core form another subsystem, which behaves as free paramagnetic atoms. Along with the antiferromagnetic core, an additional linear-in-field contribution has been detected, which is apparently related to superantiferromagnetism, i.e., the size effect inherent to small antiferromagnetic particles.
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The review summarizes the most relevant microbiological characteristics that can serve as indicators of soil ecological functions: bioresource, phytosanitary, as well as the functions of carbon ...transformation and plant nutrition. The indices of diversity and taxonomic structure of microbial communities as well as abundance of certain groups of microorganisms are estimated to characterize the bioresource function of soils. The main microbiological indicators of carbon transformation are microbial biomass carbon, the ratio of bacterial to fungal biomasses, soil respiration, enzyme activities, and the rate of soil organic matter decomposition. The appropriate microbiological indicators of the plant nutrition function of soil are the enzyme activities associated with the nitrogen and phosphorus cycles, as well as molecular species-specific markers of arbuscular mycorrhiza. Gene abundances of phytopathogens and their antagonists can serve as indicators of soil phytosanitary function. Since a high variation of some characteristics and certain difficulties in their interpretation are currently the relevant problems in microbiological indication of soil functions, the key goal is a careful selection of the parameters with the best applicability as indicators of soil ecological functions.
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Agrogenic eutrophication implies the artificial enrichment of soil with organic carbon and nutrients as a result of applying mineral and organic fertilizers to increase soil fertility and plant ...productivity. Eutrophication of gray forest soil, Luvic Retic Greyzemic Phaeozems (Loamic), has been created by annual application of increasing doses of mineral (N 90–360 kg/ha N, 75–300 kg/ha P
2
O
5
, and 100–400 kg/ha K
2
O) and organic (fresh cattle farmyard manure, 25–100 t/ha) fertilizers under plants of a five-field crop rotation for 9 years in a microplot experiment. The NPK amounts applied with manure are approximately equal to the corresponding doses of mineral fertilizers. In the systems of mineral and organic fertilization, the rates of soil enrichment with C
org
are 0.29–0.38 and 0.76–1.56 g/kg per year, respectively; with N
tot
, 0.04–0.06 and 0.06–0.09 g/kg per year; with available P
2
O
5
, 4–57 and 11–55 mg/kg per year; and with available K
2
O, 5–44 and 6–31 mg/kg per year, respectively. The doses of fertilizers in both systems are the most significant factor in the accumulation of nitrate nitrogen and available forms of phosphorus and potassium in soil, while the N
tot
content depends on the fertilization duration. The C
org
content in the soil with organic and mineral fertilizers depends on the dose of manure and the duration of NPK application, respectively. Soil eutrophication with mineral fertilizers is accompanied by a decrease in soil pH and eutrophication with organic fertilizers, on the contrary, leads to an increase in pH. It is emphasized that overfertilization and a long-term use of fertilizers are the main factors in the development of soil eutrophication and the concomitant change in soil pH.
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We present the results of a search for dark matter weakly interacting massive particles (WIMPs) in the mass range below 20 GeV/c^{2} using a target of low-radioactivity argon with a 6786.0 kg d ...exposure. The data were obtained using the DarkSide-50 apparatus at Laboratori Nazionali del Gran Sasso. The analysis is based on the ionization signal, for which the DarkSide-50 time projection chamber is fully efficient at 0.1 keVee. The observed rate in the detector at 0.5 keVee is about 1.5 event/keVee/kg/d and is almost entirely accounted for by known background sources. We obtain a 90% C.L. exclusion limit above 1.8 GeV/c^{2} for the spin-independent cross section of dark matter WIMPs on nucleons, extending the exclusion region for dark matter below previous limits in the range 1.8-6 GeV/c^{2}.
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We report on the effect of interparticle magnetic interactions in an ensemble of superparamagnetic magnetite particles with an average size of ~8.4nm dispersed in the diamagnetic matrix on the ...blocking of this ensemble in external magnetic field. The two limit cases are investigated: the case of strongly interacting particles, when the value of magnetic dipole-dipole interaction between particles is comparable with the energy of other interactions in the ensemble (the interparticle distance is similar to the nanoparticle diameter) and the case of almost noninteracting particles distant from each other by about ten particle diameters. We demonstrate that the experimental dependence of the blocking temperature on external field is described well within the model 1, in which the density of particles in a nonmagnetic medium is taken into account and the correlation value depends on external magnetic field. The model for describing the magnetic properties of a disperse nanoparticle ensemble is proposed, which makes corrections related to the particle size and mean dipole-dipole interaction energy for the anisotropy constant. The surface magnetic anisotropy of Fe3O4 particles and parameters of the interparticle coupling are estimated.
•The interparticle interactions affect superparamagnetic behavior of nanoparticles;•Effective magnetic anisotropy constant depends on interparticle interaction energy;•Modified random anisotropy model was used for 3-D dispersed nanoparticles ensemble.
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Temperature and moisture are the main external factors controlling organic matter decomposition and mineralization in soil. The effect of temperature (8 and 22°C) and moisture (15, 30, and 45 mass %) ...of gray forest soil (Luvic Retic Greyzemic Phaeozems (Loamic)) on decomposition of tree residues (leaves, small twigs, thin roots) and agricultural plants (clover aboveground mass and roots, barley straw and roots) has been studied in two long-term experiments. Coarsely crushed (10–2 mm) plant residues were added to the soil in dry form in an amount of 1% of the soil mass. The decomposition of soil organic matter and plant residues were assessed by the quantification of C–CO
2
emitted from the soil. The efficiency and rate of decomposition of soil organic matter and plant residues depended on the type of decomposed material rather than on the temperature and moisture levels. The predominant decomposition of easily decomposable components hid the temperature response of stable compounds and low-quality plant residues. The slowly decomposable plant residues were more sensitive to soil wetting. Temperature coefficients
Q
10
of mineralization of soil organic matter and plant residues were on average 1.66 ± 0.41 and 1.39 ± 0.06, respectively. Moisture coefficients
W
10
in the gravimetric moisture intervals of 15–30 and 30–45% were 1.22 ± 0.09 and 1.21 ± 0.05 for soil and 1.29 ± 0.20 and 1.25 ± 0.13 for plant residues respectively.
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•Nickel oxide nanoparticles with an average size of ~8 nm were synthesized by thermal decomposition of nickel oxalate.•New magnetic subsystems are formed in these nanoscale antiferromagnetic ...particles.•Magnetic hysteresis in NiO nanoparticles was studied using both standard quasi-static (VSM) measurements and strong pulsed magnetic fields of up to 130 kOe.•Interaction between magnetic subsystems causes complex character of magnetization switching.
We report on the investigations of a system of 8-nm NiO particles representing antiferromagnetic (AFM) materials, which are weak magnetic in the form of submicron particles, but can be considered to be magnetoactive in the form of nanoparticles due to the formation of the uncompensated magnetic moment in them. The regularities of the behavior of magnetization switching in AFM nanoparticles are established by studying the magnetic hysteresis loops under standard quasi-static conditions and in a quasi-sinusoidal pulsed field of up to 130 kOe with pulse lengths of 4–16 ms. The magnetic hysteresis loops are characterized by the strong fields of the irreversible magnetization behavior, which is especially pronounced upon pulsed field-induced magnetization switching. Under the pulsed field-induced magnetization switching conditions, which are analogous to the dynamic magnetic hysteresis, the coercivity increases with an increase in the maximum applied field H0 and a decrease in the pulse length. This behavior is explained by considering the flipping of magnetic moments of particles in an external ac magnetic field; however, in contrast to the case of single-domain ferro- and ferrimagnetic particles, the external field variation rate dH/dt is not a universal parameter uniquely determining the coercivity. At the dynamic magnetization switching in AFM nanoparticles, the H0 value plays a much more important role. The results obtained are indicative of the complex dynamics of the interaction between magnetic subsystems formed in AFM nanoparticles.
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We report on the search for dark matter weakly interacting massive particles (WIMPs) in the mass range below 10 GeV=c2 from the analysis of the entire dataset acquired with a low-radioactivity argon ...target by the DarkSide-50 experiment at Laboratori Nazionali del Gran Sasso. The new analysis benefits from more accurate calibration of the detector response, improved background model, and better determination of systematic uncertainties, allowing us to accurately model the background rate and spectra down to 0.06 keVer. A 90% C.L. exclusion limit for the spin-independent cross section of 3 GeV=c2 mass WIMP on nucleons is set at 6 × 10-43 cm2, about a factor 10 better than the previous DarkSide-50 limit. This analysis extends the exclusion region for spin-independent dark matter interactions below the current experimental constraints in the 1.2, 3.6 GeV=c2 WIMP mass range.
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