Intense, broadband near-infrared (NIR) photoluminescence was found in Cu2+-doped LiAl5O8 cubic spinel-related phase. The luminescence intensity depends strongly on the stoichiometry of the LiAl5O8 crystal host. It reaches a maximum in lithium-deficient specimens with an atomic Al/Li ratio greater than 5, while being relatively weak in stoichiometric and lithium-rich (Al/Li < 5) samples. This phenomenon can be explained by the formation of different octahedrally-coordinated Cu2+ impurity centers, which depend on the exact LiAl5O8 stoichiometry. We propose that in the lithium-deficient phase, a Cu2+ ion preferentially substitutes for two Li (+) cations, creating a Cu2+ center adjacent to a Li (+) vacancy. This specific type of center is responsible for the intense NIR photoluminescence. In contrast, in lithium-rich LiAl5O8, impurity Cu2+ centers are formed by simultaneously substituting of two Cu2+ cations for an Al3+-Li+ pair (all in octahedral coordination). These centers do not exhibit NIR photoluminescence. The photoluminescence excitation spectra of copper-doped LiAl5O8 are typical for octahedrally coordinated Cu2+. Both the emission and excitation spectra show a vibronic structure and a zero-phonon line at 77 K. The luminescence decay kinetics is single-exponential with a characteristic time of 65.4 mu s at 293 K. We also observed NIR photoluminescence with similar spectral characteristics in Cu2+-doped MgAl2O4, ZnAl2O4, MgGa2O4, and ZnGa2O4 spinels. However, its intensity was significantly weaker than in Cu2+:LiAl5O8.

We report the observation of room-temperature near-infrared (NIR) photoluminescence (PL) of octahedrally coordinated Cu2+ impurity ions in the spinel-like cubic phase LiGa5O8. A comparative study of Cu2+ and Ni2+-doped LiGa5O8 with varied Li/Ga ratios reveals that the stoichiometry of the host matrix plays a decisive role in the formation of optically active impurity centers. In lithium-deficient samples, both Cu2+ and Ni2+ form a photoluminescent center associated with cation substitution at the 4b octahedral site, charge-compensated by a lithium vacancy. In lithium-excess samples, a different substitution mechanism involving both 4b and 12d octahedral sites leads to the formation of multiple emitting centers for Ni2+, whereas the Cu2+ PL is quenched. The Ni2+:LiGa5O8 phosphors exhibit a photoluminescence quantum yield approaching 100% at room temperature with temperature-independent decay kinetics up to 300 K, while Cu2+:LiGa5O8 exhibits strong non-radiative relaxation due to stronger electron-phonon coupling. The absence of excited-state absorption in the two-level d9 system of Cu2+ and the broad tunable NIR emission of Ni2+ impurities make doped LiGa5O8 a promising host for solid-state laser applications. Furthermore, the sensitivity of the photoluminescence properties to the Li/Ga ratio suggests that transition-metal ions can serve as luminescent probes in this recently discovered ultrawide-bandgap semiconductor.

The paper presents the results of comparing the atmospheric carbon dioxide reanalysis data and phenological phases of large freshwater areas located in the boreal and subarctic zone for 2012–2020. The data from the CAMS global greenhouse gas reanalysis, which are three-dimensional fields of aerosols and chemical constituents in the atmosphere, with full coverage of the globe, were used in this work. The data used in this study were the average CO2 content in the air column over the water areas. The phenological phases of freshwater bodies (water surface, ice cover, ice destruction) were determined using data from the MIRAS microwave radiometer of the SMOS satellite. The comparison and analysis showed that the CO2 concentration in the atmosphere over the studied water areas has a seasonal cyclic character. The minimum concentration corresponds to the summer period due to strong photosynthesis in water areas, as a result of which carbon dioxide is absorbed in the water column. The maximum concentration of CO2 over water areas corresponds to the period of destruction of the ice cover, leading to the release of carbon dioxide accumulated during the winter period, which is “sealed” in the ice and in the water column under the ice. In freezing lakes located in the boreal zone, in addition to the stable spring CO2 maximum, a strong short-term release of carbon dioxide is sometimes observed, also corresponding to the stage of ice cover destruction. This emission is explained by the higher bioproductivity of water bodies in the boreal zone compared to water areas in the subarctic zone.

Tubulins are among the most successful targets for cancer chemotherapy. However, the emergence of drug resistance stimulates the continuous search for novel chemotherapeutics. Here, we discover that coumarin-30, a widely available laser dye, binds to the colchicine site of tubulin and inhibits microtubule dynamics and cancer cell division at submicromolar concentrations. By combining coumarin-30 as a fluorescent probe with the microscale thermophoresis approach, we develop a versatile assay for detecting tubulin–ligand interactions and simultaneously sorting ligands into binders of the colchicine site versus other protein pockets. The assay’s performance is demonstrated on a wide panel of compounds. Using this methodology, we identify several potent tubulin polymerization inhibitors and determine their binding sites. The results are verified with studies of microtubule dynamics in vitro and the cell cycle in cancer cell culture. Thus, the coumarin-30-based assay is a fast, accurate, and cost-effective method for characterizing tubulin ligands with diverse binding pockets.

The paper presents a model of microwave emission from mouth regions of Arctic rivers taking into account radiometer pixel contamination by land. Modeling of seasonal and interannual dynamics of brightness temperature of different regions of the Yenisei Bay is performed on the example of MIRAS radiometer data from the SMOS satellite. The necessity of considering the coastal zone in brightness temperature modeling in the studied regions is shown. Comparison of the model calculations with SMOS L1C data has shown a good agreement. Analysis of model calculations and satellite data has allowed us to determine the location of the fresh and salt water mixing zone in the Yenisei Bay during the ice period, provided that the model takes into account the coastal zone captured by the radiometer pixel.

This study demonstrates the application of the strain-kinetic criterion of fatigue failure to describe the kinetics of damage accumulation and limit states in a material with a crack under low-cycle loading. The deformations of the crack faces are assumed to be the calculated deformation parameters. An experimental investigation was conducted to study the softening of TC steel at the stable crack propagation stage. The exhaustion of limit states in a material with a crack under both static and cyclic loading is considered the critical threshold. Additionally, the definition of the bearing capacity of a material with a crack, along with its depletion under static and cyclic loading, is presented.

The climatic changes taking place in Northern Eurasia, which have become especially aggravated in the past few decades, in combination with the anthropogenic impact on ecosystems, are causing noticeable changes in the hydrological characteristics of mineral lakes. Based on the results of daily measurements of brightness temperature Tb from the SMOS (Soil Moisture and Ocean Solution) satellite, the long-term seasonal dynamics of hydrological changes in some large mineral lakes of Northern Eurasia (Caspian Sea, Kara-Bogaz-Gol Bay, Aral Sea, lakes Sarykamyshskoe, Kulunda, Ubsu-Nur) from 2012 to 2022 was studied. The analysis of the seasonal and interannual dynamics of Tb and thermodynamic temperature of the underlying surface was performed on the basis of the SMOS L1C and MODIS MOD11A1 (Moderate Resolution Imaging Spectroradiometer) products, respectively. Four periods were identified with different behavior of the radiative characteristics of mineral lakes, associated with a decrease in temperature below the freezing point of salt water, the formation and melting of ice cover on the water surface, changes in the area of the water table, and salinity of water. In the northern Caspian Sea, the influence of the phenological phases of ice cover on the change in the microwave radiation of the underlying surface was noted. The features of microwave radiation of the western (deep water) and northern parts of the Aral Sea are studied. The seasonal dynamics of Tb is associated with the processes of formation of ice cover on the water surface. Judging by the changed seasonal dynamics of the Tb, the Sarykamysh Lake was transformed into a year-round ice-free lake. Peculiarities of the seasonal dynamics of Tb for Lake Ubsu-Nur are revealed that may be associated with rainfall in the winter–spring season, as well as with the early opening of rivers and flooding of the ice cover of the lake with river water.

The rubidium barium polyphosphate RbBa2(PO3)5 containing impurity bismuth monocations has been prepared via crystallization from a melt with the stoichiometric composition and melts containing excess of rubidium or barium. The samples thus obtained demonstrate broadband photoluminescence in the Near-IR. Analysis of their photoluminescence properties leads us to conclude that they contain two types of emission centers and that predominant formation of one of them depends on melt composition. Our results show that one of the emissive centers is a bismuth monocation substituting for a barium cation and that it forms mainly from barium-deficient melts. The other emissive center, a Bi+ monocation substituting on the rubidium site, results predominantly from crystallization of rubidium-deficient melts.

We were able to observe an intense, broadband photoluminescence in different crystal hosts, doped with $\mathrm {C u}^{2+}$. These matrices include corundum (alpha-Al 2 O 3 ), different spinels: $\mathrm {M g A l}_{2} \mathrm{O}_{4}, \mathrm{MgGa}_{2} \mathrm{O}_{4}, \mathrm{ZnAl}_{2} \mathrm{O}_{4}, \mathrm{ZnGa}_{2} \mathrm{O}_{4}$, spinel-like compounds $\mathrm{LiAl}_{5} \mathrm{O}_{8}, \mathrm{LiGa}_{5} \mathrm{O}_{8}$, perovskites $\mathrm{LaAlO}_{3}, \mathrm{GdAlO}_{3}$. The main common feature of these materials is the large magnitude of the crystal field, which contributes to the appearance of photoluminescence. Otherwise, the strong electron-phonon coupling in the ground state due to the manifestation of the Jahn-Teller effect can lead to photoluminescence quenching due to the high rate of non-radiative relaxation. It has also been demonstrated that codoping with divalent ions dramatically enhances the photoluminescence of copper in corundum and perovskites.

Copper‐doped corundum (α‐Al 2 O 3 ) possesses an intense broadband photoluminescence in the near infrared. This photoluminescence is originated from Cu 2+ ions, which substitute for Al 3+ ions in corundum lattice. Co‐doping with Ge is necessary to obtain the luminescent material. It seems, that simultaneous introduction of Ge is needed to provide the charge compensation for heterovalent Cu 2+ → Al 3+ substitution, in such a way that the whole process (Cu 2+ , Ge 4+ ) → 2Al 3+ is charge‐balanced. The broad photoluminescence spectrum matches well with transparency window of silica optical fibers and the quantum yield seems to be satisfactory, so copper‐doped corundum can become demanded as a new active media for solid state lasers and amplifiers. This is the first example of photoluminescence from octahedrally coordinated Cu 2+ ion in oxide materials.

— We have studied broadband (1000–1600 nm) IR photoluminescence of polycrystalline corundum (α-Al 2 O 3 ) samples containing copper impurity ions and additionally doped with ions of elements in the oxidation state 4+: Si 4+ , Ge 4+ , Ti 4+ , Zr 4+ , Hf 4+ , and Sn 4+ . The results demonstrate that the IR photoluminescence intensity in corundum singly doped with copper is rather low. Additional doping of corundum with some tetravalent cations sharply increases the luminescence intensity. The largest increase in Cu 2+ IR photoluminescence intensity is obtained in the case of additional doping with Ti 4+ , Ge 4+ , or Sn 4+ cations. It seems likely that these ions ensure charge compensation when incorporated into the corundum lattice together with Cu 2+ ions, so that the substitution process can be represented as 2Al 3+ → Cu 2+ + M 4+ (M 4+ = Ti 4+ , Ge 4+ , Sn 4+ ,…). In this way, the additional doping of corundum with tetravalent ions raises Cu 2+ solubility in α-Al 2 O 3 , leading to photoluminescence enhancement in the material.

Analysis of seasonal and interannual variations of the brightness temperature of the Yenisei, Pechora, and Khatanga estuaries is performed using the SMOS (Soil Moisture and Ocean Salinity) satellite MIRAS (Microwave Imaging Radiometer using Aperture Synthesis) data for the period 2012–2020. It is shown that during the freezing period, with low river flow, Khatanga and Pechora bays are strongly influenced by the salty waters of the Laptev Sea and the Pechora Sea, respectively. In Yenisei Bay, the analysis reveals two characteristic areas for the winter period, delimited by a narrow strait between Sopochnaya Karga and Oshmarin capes. In the southern part of the bay, the water remains fresh or slightly salty, while in the northern part (north of the Sopochnaya Karga post), the water is always brackish, as this is the mixing zone of the fresh water of the Yenisei River and the salty water of the Kara Sea. The sea areas adjacent to the Yenisei and Pechora estuaries (the Kara Sea and Pechora Sea, respectively) are dynamic zones with brackish or salty water and constantly breaking ice under the influence of hydrological and climatic factors. The results show that SMOS MIRAS data can be used to estimate water salinity and movement of the transition zone under the ice in large bays and estuaries; to analyze the stability and dynamics of the Arctic sea-ice cover; and to determine the beginning of ice melt in large sea and freshwater areas.

Specific emissivity features of swamps and wetlands of Western Siberia were studied for changing seasonal conditions with the use of daily data of satellite microwave sounding. The research technique involved the analysis of brightness temperatures of the underlying surface at the test sites. Variations in seasonal dynamics of brightness temperatures were mainly caused by different rates of seasonal freezing of the upper waterlogged layer of the underlying surface and dielectric characteristics of water containing natural media (water body, soil, vegetation). We analyzed long-term trends in seasonal and annual dynamics of brightness temperatures of the underlying surface and estimated hydrological changes in the Arctic and Subarctic. The findings open up new possibilities for using satellite data in the microwave range for studying natural seasonal dynamic processes and predicting hazardous hydrological phenomena.

Кристаллизацией из расплава получены образцы полифосфата рубидия-бария RbBa 2 (PO 3 ) 5 , содержащего примесные монокатионы висмута. Использовался расплав стехиометрического состава, а также расплавы с избытком рубидия или бария. Образцы демонстрируют широкополосную фотолюминесценцию в ближнем ИК-диапазоне. На основании анализа фотолюминесценции образцов сделан вывод о наличии в них двух типов излучающих центров, преимущественное образование которых зависит от состава расплава. Показано, что один из люминесцентных центров представляет собой монокатион висмута, замещающий катион бария, причем он в основном образуется из расплавов, обедненных барием. Второй люминесцентный центр, представляющий собой монокатион Bi + в положении рубидия, образуется преимущественно при кристаллизации расплавов, обедненных рубидием.

— The rubidium barium polyphosphate RbBa 2 (PO 3 ) 5 containing impurity bismuth monocations has been prepared via crystallization from a melt with the stoichiometric composition and melts containing excess of rubidium or barium. The samples thus obtained demonstrate broadband photoluminescence in the Near-IR. Analysis of their photoluminescence properties leads us to conclude that they contain two types of emission centers and that predominant formation of one of them depends on melt composition. Our results show that one of the emissive centers is a bismuth monocation substituting for a barium cation and that it forms mainly from barium-deficient melts. The other emissive center, a Bi + monocation substituting on the rubidium site, results predominantly from crystallization of rubidium-deficient melts.

Polycrystalline samples of the mixed cyclotriphosphates KMgP3O9, KCaP3O9, RbMgP3O9, RbCaP3O9, CsCaP3O9, and CsSrP3O9 containing Bi+ bismuth impurity monocations have been prepared via crystallization from a melt of appropriate composition. The presence of Bi+ is responsible for broadband bright near-IR luminescence in all of the materials. The shape of the photoluminescence and photoluminescence excitation spectra has been shown to be determined by the nature of the alkaline earth cation in the composition in the cyclotriphosphates and the symmetry of the local environment of the Bi+ ions under the assumption that they isomorphously substitute for alkali metal cations in the crystal lattice of the cyclotriphosphates. The characteristic photoluminescence decay time is also determined by the symmetry of the local environment of Bi+.