For the first time, the fact of excitation of stimulated emission of blue, green, and red in color in air was discovered when an air mixture was irradiated at atmospheric pressure with light in the ...visible wavelength range. This phenomenon is observed only under sufficiently intense irradiation inside the reactor with reflective walls and is presumably explained by the formation of O(
1
S)–N
2
, O
2
(A
3
Σ)–N
2
, and O
2
(
1
Δ)–O
2
(
1
Δ) exciplexes and their stimulated emission. Under the conditions described, laser generation of blue, green, and red colors was observed in the air. A mechanism for a chain photochemical reaction is proposed to explain the observed phenomena.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
3.
Allelotoxicity of Soils: A Review Gorepekin, I. V.; Fedotov, G. N.; Shoba, S. A.
Eurasian soil science,
12/2022, Volume:
55, Issue:
12
Journal Article
Peer reviewed
The review considers the basic terms characterizing the accumulation of allelotoxic compounds in soil and justifies the need to study soil allelotoxicity and approaches to reduce its negative impact ...on plants. As is shown, the main sources forming soil allelotoxicity are plant and microbial exudates and the substances released during the decomposition of plant residues. Different classes of allelotoxic substances and putative mechanisms underlying the transformation of allelotoxins in soil are considered as well as the capabilities and limitations of the available approaches to the assessment of soil allelotoxicity. The presence of allelotoxins is poorly detectable by chemical assays; correspondingly, bioassays are most likely to be the best method for this purpose. Analysis of the published data suggests the approaches to decrease the negative impact of soil allelotoxicity, which rely on a decrease in the concentration or activity of allelotoxins in soil or at the seed–soil interface utilizing fixation of allelotoxins on the applied sorbents or activation of the consumption of allelotoxins by microorganisms.
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4.
Precision measurement of the neutral pion lifetime Larin, I; Zhang, Y; Gasparian, A ...
Science (American Association for the Advancement of Science),
05/2020, Volume:
368, Issue:
6490
Journal Article
Peer reviewed
Open access
The explicit breaking of the axial symmetry by quantum fluctuations gives rise to the so-called axial anomaly. This phenomenon is solely responsible for the decay of the neutral pion π
into two ...photons (γγ), leading to its unusually short lifetime. We precisely measured the decay width Γ of the Formula: see text process. The differential cross sections for π
photoproduction at forward angles were measured on two targets, carbon-12 and silicon-28, yielding Formula: see text, where stat. denotes the statistical uncertainty and syst. the systematic uncertainty. We combined the results of this and an earlier experiment to generate a weighted average of Formula: see text Our final result has a total uncertainty of 1.50% and confirms the prediction based on the chiral anomaly in quantum chromodynamics.
The influence of the water content of soil pastes on their viscosity is studied using vibrational viscometry, and the variable viscosity is explained by the structural organization of soil humic ...substances (HSs). The viscosity of pastes prepared from sod-podzolic soil increases to 4000–4200 mPa s with a decreasing water content of <36% and further remains almost the same. This contradicts the current views on the viscosity of suspensions, which should continuously increase with decreasing water content. This situation is explained by the fact that, in addition to water soil particles (aggregates and microaggregates), the soil paste contains one more component of supramolecular formations (SFs) from soil HSs, which could separate from soil gels and transit to disperse conditions. According to the literature data, the HS SFs are present in soils as fractal clusters (F-clusters) of particles–molecules. Because of the high stability of F-clusters, we can suggest the presence of soil particles in pastes sliding along F-clusters, whereas the change in the thickness of a sliding F-cluster layer has a minor effect on the viscosity of soil pastes. Our data on the viscosity of soil pastes confirm the significance of F-clusters for the formation of soil properties.
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The influence of the contact of chernozem, soddy–podzolic, and gray forest soil aggregates with water on their water stability has been studied. An increase in the contact time of soil aggregates ...with water leads to a gradual decrease in their water stability. Based on the verified salt solution effect on the water stability of soil aggregates, the water stability of the loss of aggregates in contact with water is not directly proportional to the disjoining pressure. When soil aggregates come into contact with water, fractal clusters of humus particles (F-clusters) are isolated from them. It is suggested that the F-clusters that the soil gel is based on control the physical basis of the water stability of the soil.
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In modern soil physics soil stability as a concept is divided into two directions, namely water stability and mechanical resistance to compression and wedging. Both soil properties in water-saturated ...soil are based on the rupture of interaggregate interparticle bonds, however, no standard of physically based parameters have been proposed to characterize the aggregate stability. The purpose of the article is to substantiate the physical concept of stability of soil aggregates and to propose a single methodological method for quantifying stability as a normative soil characteristic. A high-performance method has been developed based on the dissection of linearly arranged water-saturated aggregates with blades under controlled load. The main stages of the technique are vacuuming of aggregates to eliminate the uncontrolled influence of trapped air, saturation of aggregates with water in vacuum, and subsequent determination of the aggregate stability to penetration of blades. Experimental stability values (mN/aggregate) were obtained for 17 soils, which made it possible to form normative ranges for arable loamy soils, namely 17–19, 27–29, and 34–37 mN/aggregate for soddy-podzolic, gray forest soils, and chernozem, respectively, and a number of other soils, which makes it possible to apply the obtained value as a soil characteristic of the aggregate stability. The possibility of using the stability values as a methodological basis for monitoring soil stability and degradation and for quantitative directions for assessing of physical characteristics of soil aggregates (firstly, their main parameter—stability) is discussed. Taking into account the highly correlative dependence of the proposed stability characteristic on the water stability values obtained by the Savvinov method (>85%) and the high performance of the stability determination method (the proposed method is about 20 times more productive than the Savvinov method), the possibilities of using the method and the obtained values of the stability of aggregates as a general physical characteristic and a separate one for quantifying water stability are discussed.
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The application of sorption preparations (SP) based on bentonite-humate mixtures for seed stimulating treatment upon sowing into the soddy-podzolic soil (Albic Retisols (Loamic, Aric, Cutanic, ...Ochric)) was studied. The correlation between seeds’ inhibition by soil and the efficiency of SP application was found. The SP treatment was not always efficient for spring wheat cultivars. For some of the cultivars, it caused inhibition of seed germination and seedlings development. The intake of essential biologically active substances (BAS) from soils to seeds was limited in these cases because of the firm fixation of these substances in SP. The brewer’s yeast autolysate (BYA) introduced to the SP mixture made it possible to fill the active centers of sorbents and to avoid the fixation of BAS from soil. The obtained preparation eliminated inhibition of seed development at the initial stage upon SP application. The efficiency of previously known individual stimulating substances sharply increased upon their combined application with SP and BYA mixture.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Changes in the properties of soil samples during drying or heating are known. However, the reasons for them have remained unclear up to this time. Our study aims to clarify the processes occurring ...during drying–wetting and heating of wet soils by the study of the changes in the soil properties. Soddy-podzolic soils were investigated. The influence of soil drying on the water-holding capacity in the capillary and hygroscopic water ranges of the water retention curve (WRC), hydraulic conductivity, water stability of soil aggregates, and allelotoxicity has been studied. The impact of heating of wet soils on the hydrophilic-hydrophobic properties, allelotoxicity, electrical conductivity of soil water extracts, and thermal diffusivity of wet soils has also been analyzed. It is shown that soil particles become hydrophobized during drying–wetting cycles and during autoclaving, which leads to an increase in the content of allelotoxins accessible to plants. To explain the obtained data, the concept of transformation of gel structures covering and binding soil particles during drying or heating has been used. The applied model includes an assumption that primary particles of humus substances having a diphilic surface and forming fractal clusters can interact with one another in the primary and secondary minima of aggregation.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
It is common to consider the experimental soil physics results from the standpoint of a three-phase soil model. Along with the three-phase model, a gel model of soils is used. These models are based ...on different principles: in the three-phase model, solid phase constancy and liquid mobility; in the gel model, the ability of soil gels to swell, harden, and reduce water mobility. The purpose of this work is to assess the applicability of three-phase and gel soil models to analyzing the study results of some physical properties of soils. The studies were carried out with the zonal soil series: sod–podzolic, gray forest, chernozem, and chestnut soils. The following methods were used in this work: vibration viscometry, laser diffractometry, and electrical resistivity of soils. Unexpected results were obtained in the study of the soil’s physical properties. Firstly, the curve of the relationship between the moisture content of soil samples and the viscosity of pastes prepared from them reached the maximum at the point of limited availability of water (PLAW). Secondly, under the increased mechanical action on soil pastes, the particle size increased rather than decreased in them. Thirdly, the soil electrical resistivity–moisture relationship maintains a uniform course in the PLAW area. Meanwhile, at this water content, the continuous liquid phase framework providing moisture and electrical conductivity disappears in the soils. Fourthly, moist soils dry out in a desiccator over water. It is not possible to explain these results from the standpoint of the three-phase soil model generally accepted in soil science. For this reason, the gel model of soils was used to analyze and explain all the results obtained.
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