The article summarizes the results of long-term studies of microbial biomass in buried soils of archaeological sites and recent reference soils. Geographically, the objects of study are located in ...the southeast of the East-European Plain, the Caspian Lowland, the Western Caucasus, and the Crimea. A very representative data have been accumulated on the chronogeographic patterns of changes in microbial biomass in chernozems (Chernozem), chestnut soils (Haplic Kastanozems), light chestnut soils (Salic Cambisols), and solonetzes (Humic Solonetzes). Chronological framework is from the Latest Neolithic (Eneolithic) to the recent time (5700–300 years ago). The biomass of soil microbial communities has been assessed for the content of phospholipids in soil. It was found that the microbial biomass in buried soils does not depend on the soil as well as on the time of soil burial. The average content of phospholipids in buried soils was two times lower than that in modern ones, but no correlation of microbial biomass with the duration of soil buried state was found. To a greater extent, the content of phospholipids in buried soils depended on the content of silt; when it was less than 10%, the microbial biomass was minimal. Geomorphological position was a significant factor influencing the microbial biomass. Thus, the maximum values of microbial biomass are typical for soils of local watersheds and slopes of northern aspect. In solonetzes, an inverse correlation was noted between the microbial biomass and the thickness of the SEL horizon. In the cultural layers of ancient settlements, the microbial biomass exceeded the that in recent soils, and depended on land use and the volume of incoming anthropogenic substrates.
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The article considers the ways to adapt fiscal rules in the postpandemic period in the Republic of Armenia, taking into account the new challenges associated with the geopolitical situation. The ...effectiveness of existing fiscal rules during the crisis is assessed, taking into account their impact on economic recovery, fiscal sustainability, and overall economic well-being. Through a comprehensive analysis of different configurations of fiscal rules, the authors attempt to determine the balance between flexibility and discipline in fiscal policy in the postcrisis period. The study examines the trade-offs between easing fiscal rules to achieve short-term recovery growth goals and maintaining stricter rules to ensure long-term fiscal stability.
Rhombic
153
Eu
2+
and
151
Eu
2+
centers are studied in specially grown single crystals of yttrium–aluminum garnet. The parameters of the hyperfine and quadrupole interactions describing the hyperfine ...structure of the EPR spectra of both isotopes have been determined.
An edge-coloring of a graph
G
with colors
1
,
2
,
…
,
t
is called an
interval t-coloring if for each
i
∈
{
1
,
2
,
…
,
t
}
there is at least one edge of
G
colored by
i
, and the colors of edges ...incident to any vertex of
G
are distinct and form an interval of integers. In this paper we show that if
n
=
p
2
q
, where
p
is odd,
q
is nonnegative, and
2
n
−
1
≤
t
≤
4
n
−
2
−
p
−
q
, then the complete graph
K
2
n
has an interval
t
-coloring. We also prove that if
n
≤
t
≤
n
(
n
+
1
)
2
, then the
n
-dimensional cube
Q
n
has an interval
t
-coloring.
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► Crystals of L-tryptophan picrate were grown and reinvestigated. ► The structure comprises L-tryptophan L-tryptophanium dimeric cation. ► The presence of the dimeric cation is ...reflected in the IR spectrum. ► Crystals grown from water and ethanol differ from those grown from acetone.
A crystal structure redetermination of the L-tryptophan picrate crystal previously studied by Ishida et al. (Chem. Pharm. Bull. 41 (1993) 433–438) showed that it comprises L-tryptophan L-tryptophanium dimeric cation, one picrate anion and picric acid. The O⋯O distance of the O–H⋯O hydrogen bond in the dimeric cation is equal to 2.470(6)Å. The infrared spectrum of the crystal was registered and analyzed. The infrared spectrum of the crystals contains a broad absorption band centered at ca. 1170cm−1, which is assigned to the stretching vibration of the O–H bond.
The SiO
2
/ZnO nanocomposite with a core-shell structure for photocatalysis from water-soluble zinc salts and sodium silicate was synthesized using the hydrothermal-microwave method. The ...physicochemical properties of the synthesized SiO
2
/ZnO were studied and its photocatalytic activity was tested. The band gaps of the heat-treated composite
and
are 3.35 and 3.32 eV, respectively. The photocatalytic activity of the resulting SiO
2
/ZnO was determined by the decomposition reaction of methylene blue under UV irradiation. The conversion of methylene blue was determined by optical method. The resulting SiO
2
/ZnO has high photocatalytic activity. The conducted studies showed the effectiveness of microwave synthesis of SiO
2
/ZnO with a core-shell structure in comparison with traditional methods.
► A new (β-alaninium picrate) salt with β-alanine β-alaninium dimeric cation is discovered. ► Two groups of dimeric cations with short and relatively long (O⋯O) distances exist. ► There are four ...different types of A+⋯A+ dimeric cations according to conformation and symmetry. ► The title salt belongs to the group with centrosymmetrical pairs and short (O⋯O) distances.
β-Alaninium picrate crystallizes in the form of yellow columns, in the triclinic system (space group P1¯, Z=2). The asymmetric unit contains one β-alaninium cation and one picrate anion. Nevertheless, the unit cell comprises a dimeric centrosymmetric β-Ala+⋯β-Ala+ cation and two picrate anions. The O⋯O distance (2.636(2)Å) in the dimeric cation is among the shortest distances of known salts with A+⋯A+ type dimeric cations. The infrared and Raman spectra are shown and discussed. A comparison of known crystals with β-Ala+⋯β-Ala+ cations is presented, which shows that four different types can be distinguished.
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The article provides calculations of economic losses in 2020 and total losses for 2020–2021 due to the COVID-19 pandemic, as well as an econometric assessment of the impact of various indicators on ...their value in different countries of the world. Three groups of factors have been studied: macroeconomic indicators, macroeconomic policy factors, and factors describing the degree of institutional development of countries. As a result of the study, it was found that in 2020 macroeconomic policy measures did not play a significant role in mitigating the economic consequences of the crisis caused by the COVID-19 pandemic, however, fiscal policy measures contributed to the recovery process of national economies and reduced the amount of cumulative losses. Institutional factors had a similar impact.
Single crystals of YAlO
3
-Er (YAP:Er) are grown by the Bridgman method from melts with different Y/Al ratio. The structural defects and color centers are compared for Y/Al = 1 and Y/Al > 1, as well ...as formed in the processes of gamma-irradiation and thermal treatment. Based on the obtained data, the growth conditions of YAP:Er crystals free of color centers and twins are determined. Spectral-luminescent properties of crystals are investigated: the absorption and luminescent spectra are registered in the polarized light, the luminescence kinetics is investigated and the lifetime of the
4
I
13/2
level of Er
3+
ion is determined.
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