Publications by authors named "Shashkov M"

Background: Earthworms are one of the most important components of temperate ecosystems and groups of soil animals globally, but data on their distribution around the world are still incomplete and uneven. Northern Eurasia is a region for which available data on earthworm distribution is extremely poor. At the same time, generations of Soviet and Russian researchers have performed extensive research and accumulated a large amount of data on the distribution of earthworms in this vast region.

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Article Synopsis
  • Fiber mode-locked lasers produce ultrashort pulses and can have varying optical outputs based on cavity adjustments, leading to challenges due to their multistability.
  • The study showcases the use of the Soft Actor-Critic algorithm to generate a harmonic mode-locked regime in a fiber laser, utilizing an ion-gated nanotube saturable absorber.
  • This research presents a machine-learning approach to effectively manage pumping power and absorber transmission, enabling automatic adjustments to overcome the complexities of nonlinear optical systems.
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The Zr-monosubstituted Keggin-type dimeric phosphotungstate (BuN)[{PWOZr(μ-OH)(HO)}] () efficiently catalyzes epoxidation of C═C bonds in various kinds of alkenes, including terminal ones, with aqueous HO as oxidant. Less sterically hindered double bonds are preferably epoxidized despite their lower nucleophilicity. Basic additives (BuNOH) in the amount of 1 equiv per dimer suppress HO unproductive decomposition, increase substrate conversion, improve yield of heterolytic oxidation products and oxidant utilization efficiency, and also affect regioselectivity of epoxidation, enhancing oxygen transfer to sterically hindered electron-rich C═C bonds.

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Optical waveguides covered with thin films, which transmittance can be controlled by external action, are widely used in various applications from optical modulators to saturable absorbers. It is natural to suggest that the losses through such a waveguide will be proportional to the absorption coefficient of the covering material. In this letter, we demonstrate that under certain conditions, this simple assumption fails.

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The study demonstrates the possibility of using ionic liquids (IL) as a stationary liquid phase (SLP) for gas chromatographic (GC) multicapillary columns (MCC). Three types of IL of three classes were employed as SLP: Imidazolium, Pyridinium and Quinolinium. Dependences of the MCCs efficiency on the carrier gas flow rate were obtained.

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Direct oxygenation of nonactivated aliphatic C(sp)-H groups with peroxycarboxylic acids in the presence of palladium tris(pyridylmethyl)amine complex (0.6 mol %) is reported, providing the corresponding hydroxylated derivatives in up to 94% yields. The oxidation of 3° C-H groups occurs stereospecifically, with the catalyst system demonstrating extremely high sensitivity to electronic effects (adamantane oxidation: 3°:2° up to >300).

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Herein, we report the direct selective C-H lactonization of fatty acids (C5-C16), catalyzed by manganese(II) complexes bearing bis-amino-bis-pyridine ligands. The catalyst system uses the environmentally benign hydrogen peroxide as oxidant and exhibits high efficiency (100-200 TON), providing under optimized conditions γ-lactones in 60-90% yields. Remarkably, by changing the reaction conditions, the oxidation of hexanoic acid can be diverted toward formation of δ-caprolactone in up to 67% yield.

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Background: Ground beetles (Carabidae, Coleoptera) are one of the most species-rich and well-studied insect families. However, the number of published datasets is disproportionately low against the biodiversity of this group. According to GBIF, only a fifth of the percentage of all published data covers ground beetles.

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Article Synopsis
  • - This dataset focuses on earthworm species diversity, age structure, biomass, density, and seasonal activity, collected from old-growth and young forests in two protected areas in Kaluga Oblast, Russia.
  • - The study provides fresh insights into earthworm communities in European Russia, highlighting their ecological importance.
  • - A new standardization schema based on Darwin Core is proposed for soil invertebrate survey data, aiming to improve future data collection and analysis.
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Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties.

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Background: This sampling-event dataset provides primary data about species diversity, population and seasonal activity of ground beetles (Carabidae, Coleoptera). The study was carried out in broad-leaved forests of protected ("Kaluzhskiye Zaseki" Nature Reserve and Ugra National Park) and urban areas (the Kaluga City) of the Kaluga Oblast. Carabids were collected from April to October during 1995-1998 by pitfall traps.

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Article Synopsis
  • - Species rely on environmental cues, like degree-days, to time their phenological events and exhibit varying responses based on their location and the season.
  • - The study analyzed data from 91 taxa across 472 sites in the former Soviet Union, finding that spring phenological events advance more consistently with temperature cues (cogradient variation), while autumn events are less responsive (countergradient variation).
  • - Despite some local adaptations, phenological events generally do not keep pace with environmental cues, particularly lagging further in earlier years, suggesting differing impacts of climate change on spring and autumn species responses.
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We present an extensive, large-scale, long-term and multitaxon database on phenological and climatic variation, involving 506,186 observation dates acquired in 471 localities in Russian Federation, Ukraine, Uzbekistan, Belarus and Kyrgyzstan. The data cover the period 1890-2018, with 96% of the data being from 1960 onwards. The database is rich in plants, birds and climatic events, but also includes insects, amphibians, reptiles and fungi.

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Soil organisms, including earthworms, are a key component of terrestrial ecosystems. However, little is known about their diversity, their distribution, and the threats affecting them. We compiled a global dataset of sampled earthworm communities from 6928 sites in 57 countries as a basis for predicting patterns in earthworm diversity, abundance, and biomass.

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This work addresses the supramolecular self-organization in the xerogels of formose reaction products. The UV-induced formose reaction was held in over-saturated formaldehyde solutions at 70C without a catalyst. The solutions of the obtained carbohydrates were dried on a glass slide, and the obtained xerogels demonstrated a prominent optical activity, while the initial solutions were optically inactive.

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New strains of green microalgae were isolated and screened for growth and the production of lipids from municipal wastewater. It was shown that the strain Micractinium sp. IC-76 has a biomass productivity of 37.

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We describe the application of columns with highly polar stationary liquid phases based on pyridinium ionic liquids for the two-dimensional chromatography separation of bio-oil and product of coal pyrolysis. By using inverse combination columns-a first ionic liquid column and a second nonpolar column-good separation results have been obtained. In the analysis of coal pyrolysis products, the suggested approach provides a much better resolution between components in comparison with a less polar first-dimension column (based on polyethylene glycol).

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The effect of intra- and interspecific competition on the spatial distribution of the biomass and mortmass of woody plant roots in mixed tree stands has been studied. It has been found that the mass of roots in the samples from tree pairs of different species is higher than in the samples from monospecific pairs. Species-specific differences in the vertical distribution of roots and the effect of intra- and interspecific competition on the spatial structure of biomass have been shown.

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Recent advances in the development of new liquid phases (ILs) made it possible to use some classes of ILs as polar stationary liquid phases (SLP). In our days only alkylimidazolium- and alkylphosphonium-based ILs are widely used as polar SLP. In present work some other types of ILs - pyridinium and cyanopropyl/hydroxypropyl imidazolium were investigated as SLP.

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Mass spectra were obtained to evaluate the use of numerous single-cation and dicationic ionic liquids as stationary liquid phases in GC/MS at high temperature. Background mass spectra and product ion mass spectra of several ions in the background spectrum were obtained. Fragmentation mechanisms were propounded, including the detailed fragmentation pathway of the 1,2-dimethyl-3-propylimidazole cation.

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