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The Global Climate Observing System and Global Terrestrial Observing Network have identified permafrost as an 'Essential Climate Variable,' for which ground temperature and active layer dynamics are key variables. This work presents long-term climate, and permafrost monitoring data at seven sites representative of diverse climatic and environmental conditions in the western Russian Arctic. The region of interest is experiencing some of the highest rates of permafrost degradation globally. Since 1970, mean annual air temperatures and precipitation have increased at rates from 0.05 to 0.07 °C yr−1 and 1 to 3 mm yr−1 respectively. In response to changing climate, all seven sites examined show evidence of rapid permafrost degradation. Mean annual ground temperatures increases from 0.03 to 0.06 °C yr−1 at 10-12 m depth were observed in continuous permafrost zone. The permafrost table at all sites has lowered, up to 8 m in the discontinuous permafrost zone. Three stages of permafrost degradation are characterized for the western Russian Arctic based on the observations reported.

There is a long time gap between the formulation of the basic theory of low-dimensional (low-D) magnetism as advanced by Ising, Heisenberg and Bethe and its experimental verification. The latter started not long before the discovery of high- T C superconductivity in cuprates and has been boosted by this discovery result in an impressive succession of newly observed physical phenomena. Milestones on this road were the compounds which reached their quantum ground states upon lowering the temperature either gradually or through different instabilities. The gapless and gapped ground states for spin excitations in these compounds are inherent for isolated half-integer spin and integer spin chains, respectively. The same is true for the compounds hosting odd and even leg spin ladders. Some complex oxides of transition metals reach gapped ground state by means of spin-Peierls transition, charge ordering or orbital ordering mechanisms. However, the overwhelming majority of low-dimensional systems arrive to a long-range ordered magnetic state, albeit quite exotic realizations. Under a magnetic field some frustrated magnets stabilize multipolar order, e.g., showing a spin-nematic state in the simplest quadropolar case. Finally, numerous square, triangular, kagome and honeycomb layered lattices, along with Shastry–Sutherland and Nersesyan–Tsvelik patterns constitute the playground to check the basic concepts of two-dimensional magnetism, including resonating valence bond state, Berezinskii–Kosterlitz–Thouless transition and Kitaev model.

Polar bears are of international conservation concern due to climate change but are difficult to study because of low densities and an expansive, circumpolar distribution. In a collaborative U.S.-Russian effort in spring of 2016, we used aerial surveys to detect and estimate the abundance of polar bears on sea ice in the Chukchi Sea. Our surveys used a combination of thermal imagery, digital photography, and human observations. Using spatio-temporal statistical models that related bear and track densities to physiographic and biological covariates (e.g., sea ice extent, resource selection functions derived from satellite tags), we predicted abundance and spatial distribution throughout our study area. Estimates of 2016 abundance ( N ^ * ) ranged from 3,435 (95% CI: 2,300-5,131) to 5,444 (95% CI: 3,636-8,152) depending on the proportion of bears assumed to be missed on the transect line during Russian surveys ( g (0)). Our point estimates are larger than, but of similar magnitude to, a recent estimate for the period 2008-2016 ( N ^ * = 2 , 937 ; 95% CI 1,522-5,944) derived from an integrated population model applied to a slightly smaller area. Although a number of factors (e.g., equipment issues, differing platforms, low sample sizes, size of the study area relative to sampling effort) required us to make a number of assumptions to generate estimates, it establishes a useful lower bound for abundance, and suggests high spring polar bear densities on sea ice in Russian waters south of Wrangell Island. With future improvements, we suggest that springtime aerial surveys may represent a plausible avenue for studying abundance and distribution of polar bears and their prey over large, remote areas.

Terbium tritelluride, TbTe3, orders antiferromagnetically in three steps at TN1 = 6.7 K, TN2 = 5.7 K, and TN3 = 5.4 K, preceded by a correlation hump in magnetic susceptibility at T* ~8 K. Combining thermodynamic, i.e., specific heat Cp and magnetization M, and transport, i.e., resistance R, measurements we established the boundaries of two commensurate and one charge density wave modulated phases in a magnetic field oriented along principal crystallographic axes. Based on these measurements, the magnetic phase diagrams of TbTe3 at H‖a, H‖b and H‖c were constructed.

We compare the upper critical field of bulk single-crystalline samples of the two intrinsic transition metal dichalcogenide superconductors, 2H-NbSe 2 and 2H-NbS 2 , in high magnetic fields where their layer structure is aligned strictly parallel and perpendicular to the field, using magnetic torque experiments and a high-precision piezo-rotary positioner. While both superconductors show that orbital effects still have a significant impact when the layer structure is aligned parallel to the field, the upper critical field of NbS 2 rises above the Pauli limiting field and forms a Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) state, while orbital effects suppress superconductivity in NbSe 2 just below the Pauli limit, which excludes the formation of the FFLO state. From the out-of-plane anisotropies, the coherence length perpendicular to the layers of 31 Å in NbSe 2 is much larger than the interlayer distance, leading to a significant orbital effect suppressing superconductivity before the Pauli limit is reached, in contrast to the more 2D NbS 2 .

The synthesis of bacterial cellulose (BC) by Komagataeibacter xylinus strain B-12068 was investigated on various C-substrates, under submerged conditions with stirring and in static surface cultures. We implemented the synthesis of BC on glycerol, glucose, beet molasses, sprat oil, and a mixture of glucose with sunflower oil. The most productive process was obtained during the production of inoculum in submerged culture and subsequent growth of large BC films (up to 0.2 m2 and more) in a static surface culture. The highest productivity of the BC synthesis process was obtained with the growth of bacteria on molasses and glycerol, 1.20 and 1.45 g/L per day, respectively. We obtained BC composites with silver nanoparticles (BC/AgNPs) and antibacterial drugs (chlorhexidine, baneocin, cefotaxime, and doripenem), and investigated the structure, physicochemical, and mechanical properties of composites. The disc-diffusion method showed pronounced antibacterial activity of BC composites against E. coli ATCC 25922 and S. aureus ATCC 25923.

Background Topical non-steroidal anti-inflammatory drugs have the potential to reduce treatment burden and improve outcomes of anti-VEGF therapy for a number of retinal disorders, including neovascular age-related macular degeneration, diabetic macular edema, and retinal vein occlusions. In this review, we focused on the advantages of topical bromfenac as an adjunct to intravitreal anti-VEGF therapy in VEGF-driven maculopathies. Methods Cochrane Library, PubMed, and EMBASE were systematically reviewed to identify the relevant studies of neovascular age-related macular degeneration, diabetic macular edema, macular edema associated with retinal vein occlusion, myopic choroidal neovascularization, and radiation maculopathy which reported changes in central retinal thickness, visual acuity, and the number of anti-VEGF injections needed when anti-VEGF therapy was combined with topical bromfenac. Results In total, ten studies evaluating bromfenac as an adjunct to anti-VEGF therapy were identified. Five studies were included in meta-analysis of the number of injections and five studies were included in the analysis of changes in central retinal thickness. A statistically significantly lower number of intravitreal injections ( p  = 0.005) was required when bromfenac was used as an adjunct to anti-VEGF therapy compared to anti-VEGF monotherapy with pro re nata regimen. At the same time, eyes receiving bromfenac as an adjunct to anti-VEGF therapy demonstrated non-inferior outcomes in central retinal thickness ( p  = 0.07). Except for one study which reported better visual outcomes with combined treatment, no difference in visual acuity or clinically significant adverse effects were reported. Conclusions This literature review and meta-analysis showed that topical bromfenac can be considered as a safe adjunct to anti-VEGF therapy with a potential to reduce the treatment burden with anti-VEGF drugs requiring frequent injections without compromising improvement of central retinal thickness or visual acuity.

Rapid Arctic warming is expected to result in widespread permafrost degradation. However, observations show that site-specific conditions (vegetation and soils) may offset the reaction of permafrost to climate change. This paper summarizes 43 years of interannual seasonal thaw observations from tundra landscapes surrounding the Marre-Sale on the west coast of the Yamal Peninsula, northwest Siberia. This robust dataset includes landscape-specific climate, active layer thickness, soil moisture, and vegetation observations at multiple scales. Long-term trends from these hierarchically scaled observations indicate that drained landscapes exhibit the most pronounced responses to changing climatic conditions, while moist and wet tundra landscapes exhibit decreasing active layer thickness, and river floodplain landscapes do not show changes in the active layer. The slow increase in seasonal thaw depth despite significant warming observed over the last four decades on the Yamal Peninsula can be explained by thickening moss covers and ground surface subsidence as the transient layer (ice-rich upper permafrost soil horizon) thaws and compacts. The uneven proliferation of specific vegetation communities, primarily mosses, is significantly contributing to spatial variability observed in active layer dynamics. Based on these findings, we recommend that regional permafrost assessments employ a mean landscape-scale active layer thickness that weights the proportions of different landscape types.

From 2015 to 2020, using the spectral gradient radiometric method, the possibility of the frozen/thawed (FT) state identification of tundra soil was investigated based on Soil Moisture Active Passive (SMAP) and Global Change Observation Mission – Water Satellite 1 (GCOM-W1) satellite observations of 10 test sites located in the Arctic regions of Canada, Finland, Russia, and the USA. It is shown that the spectral gradients of brightness temperature and reflectivity (measured in the frequency range from 1.4 to 36.5 GHz with horizontal polarization, a determination coefficient from 0.775 to 0.834, a root-mean-square error from 6.6 to 10.7 d and a bias from −3.4 to +6.5 d) make it possible to identify the FT state of the tundra topsoil. The spectral gradient method has a higher accuracy with respect to the identification of the FT state of tundra soils than single-frequency methods based on the calculation of polarization index.

A series of six seven-coordinate pentagonal-bipyramidal (PBP) erbium complexes, with acyclic pentadentate [N3O2] Schiff-base ligands, 2,6-diacetylpyridine bis-(4-methoxybenzoylhydrazone) [H2DAPMBH], or 2,6-diacethylpyridine bis(salicylhydrazone) [H4DAPS], and various apical ligands in different charge states were synthesized: [Er(DAPMBH)(C2H5OH)Cl] (1); [Er(DAPMBH)(H2O)Cl]·2C2H5OH (2); [Er(DAPMBH)(CH3OH)Cl] (3); [Er(DAPMBH)(CH3OH)(N3)] (4); [(Et3H)N]+[Er(H2DAPS)Cl2]− (5); and [(Et3H)N]+[Y0.95Er0.05(H2DAPS)Cl2]− (6). The physicochemical properties, crystal structures, and the DC and AC magnetic properties of 1–6 were studied. The AC magnetic measurements revealed that most of Compounds 1–6 are field-induced single-molecule magnets, with estimated magnetization energy barriers, Ueff ≈ 16–28 K. The experimental study of the magnetic properties was complemented by theoretical analysis based on ab initio and crystal field calculations. An experimental and theoretical study of the magnetism of 1–6 shows the subtle impact of the type and charge state of the axial ligands on the SMM properties of these complexes.