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.
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.
The homogeneous high-entropy wolframite-type solid solution (Mn
Co
Ni
Cu
Cd
)WO
was prepared by solid-state reaction at 1000 °C. Elongated "crystals" were grown from the Na
WO
flux, but their ...strongly broadened powder X-ray diffraction patterns indicated partial dissolution. Nevertheless, successive annealing of the homogeneous solid solution for 3-4 h at 800, 700, and 600 °C did not bring any sign of dissolution. Thus, the material is kinetically stable at low temperatures although thermodynamically unstable. The long-range antiferromagnetic order was established at
∼ 24.8 K. Based on magnetization and specific heat measurements, a magnetic phase diagram was built, demonstrating the presence of an additional field-induced phase. In contrast to the parent MnWO
, no dielectric anomaly has been found down to 2 K.
The homogeneous high-entropy wolframite-type solid solution (Mn1/5Co1/5Ni1/5Cu1/5Cd1/5)WO4 was prepared by solid-state reaction at 1000 °C. Elongated “crystals” were grown from the Na2WO4 flux, but ...their strongly broadened powder X-ray diffraction patterns indicated partial dissolution. Nevertheless, successive annealing of the homogeneous solid solution for 3–4 h at 800, 700, and 600 °C did not bring any sign of dissolution. Thus, the material is kinetically stable at low temperatures although thermodynamically unstable. The long-range antiferromagnetic order was established at T N ∼ 24.8 K. Based on magnetization and specific heat measurements, a magnetic phase diagram was built, demonstrating the presence of an additional field-induced phase. In contrast to the parent MnWO4, no dielectric anomaly has been found down to 2 K.
We report the first highly conducting single-molecule magnet, (BEDO)4ReF6·6H2O 1; BEDO = bis(ethylenedioxo)tetrathiafulvalene, whose conductivity and single-molecule magnetism coexist in the same ...temperature range. The compound was synthesized by BEDO electrocrystallization in the presence of (Ph4P)2ReF6·2H2O and characterized by crystallography and measurements of the conductivity and alternating-current magnetic susceptibility.
Submarine permafrost is perennially cryotic earth material that lies offshore. Most submarine permafrost is relict terrestrial permafrost beneath the Arctic shelf seas, was inundated after the last ...glaciation, and has been warming and thawing ever since. As a reservoir and confining layer for gas hydrates, it has the potential to release greenhouse gasses and impact coastal infrastructure, but its distribution and rate of thaw are poorly constrained by observational data. Lengthening summers, reduced sea ice extent and increased solar heating will increase water temperatures and thaw rates. Observations of gas release from the East Siberian shelf and high methane concentrations in the water column and air above it have been attributed to flowpaths created in thawing permafrost. In this context, it is important to understand the distribution and state of submarine permafrost and how they are changing. We assemble recent and historical drilling data on regional submarine permafrost degradation rates and review recent studies that use modelling, geophysical mapping and geomorphology to characterize submarine permafrost. Implications for submarine permafrost thawing are discussed within the context of methane cycling in the Arctic Ocean and global climate change.
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.
The distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs) in soils has been shown to correlate with pH and mean annual air temperature. Because of this dependence brGDGTs have ...found an application as palaeoclimate proxies in coastal marine sediments, based on the assumption that their distribution is not altered during the transport from soils to marine systems by rivers. To study the processes acting on the brGDGT distributions, we analysed the full suite of brGDGTs, including the recently described 6-Me brGDGTs, in both the suspended particulate matter (SPM) of the Siberian Yenisei River and the SPM and sediments of its outflow in the Kara Sea. The brGDGT distribution in the SPM of the Yenisei River was fairly constant and characterized by high abundances of the 6-Me brGDGTs, reflecting their production at the neutral pH of the river water. However, the brGDGT distribution showed marked shifts in the marine system. Firstly, in the Yenisei River Mouth, the fractional abundance of the 6-Me brGDGTs decreases sharply. The brGDGT signature in the Yenisei River Mouth possibly reflects brGDGTs delivered during the spring floods that may carry a different distribution. Also, coastal cliffs were shown to contain brGDGTs and to influence especially those sites without major river inputs (e.g. Khalmyer Bay). Further removed from the river mouth, in-situ production of brGDGTs in the marine system influences the distribution. However, also the fractional abundance of the tetramethylated brGDGT Ia increases, resulting in a distribution that is distinct from in-situ produced signals at similar latitudes (Svalbard). We suggest that this shift may be caused by preferential degradation of labile (riverine in-situ produced) brGDGTs and the subsequent enrichment in less labile (soil) material. The offshore distribution indeed agrees with the brGDGT distribution encountered in a lowland peat. This implies that the offshore Kara Sea sediments possibly carry a soil-dominated signal, indicating potential for palaeoclimate reconstructions at this site.
Both in the river system and coastal cliffs, brGDGTs were much more abundant than crenarchaeol, an archaeal isoprenoid GDGT, resulting in high (>0.93) Branched and Isoprenoid Tetraether (BIT) index values. Moving downstream in the marine sediments, a decrease in brGDGT concentrations, coeval with an increase in crenarchaeol, resulted in decreasing BIT index values. This decrease correlates with changes in bulk proxies for terrigenous input (δ13Corg, C/N), confirming the use of the BIT index to trace the delivery of river-transported and coastal cliff-derived terrigenous organic matter.
A series of reactions of Cp(CO)
2
Mn&z.dbd;C&z.dbd;CHPh with different gold(
i
) complexes of Au-C&z.tbd;C-R
n
(R = 4-C
5
H
4
N, C
6
H
5
) and (tht)AuCl yielded one novel trinuclear MnAuMn cluster. ...The structure of this cluster can be rationalized as being formed of a vinylidene Mn-Au binuclear and Mn-acetylide fragments, and the binding between those is achieved mainly through the sharing of the electron pair of the single Mn-C σ-bond of an acetylide unit with the gold center.
Several reactions of Cp(CO)
2
Mn&z.dbd;C&z.dbd;CHPh with gold(
i
) complexes resulted in the formation of one trinuclear MnAuMn cluster, which basically can be represented as the complex of Au with two Mn-containing metalloligands.
The recessive form of dystrophic epidermolysis bullosa (RDEB) is a debilitating disease caused by impairments in the junctions of the dermis and the basement membrane of the epidermis. Mutations in ...the COL7A1 gene induce multiple abnormalities, including chronic inflammation and profibrotic changes in the skin. However, the correlations between the specific mutations in COL7A1 and their phenotypic output remain largely unexplored. The mutations in the COL7A1 gene, described here, were found in the DEB register. Among them, two homozygous mutations and two cases of compound heterozygous mutations were identified. We created the panel of primary patient-specific RDEB fibroblast lines (FEB) and compared it with control fibroblasts from healthy donors (FHC). The set of morphological features and the contraction capacity of the cells distinguished FEB from FHC. We also report the relationships between the mutations and several phenotypic traits of the FEB. Based on the analysis of the available RNA-seq data of RDEB fibroblasts, we performed an RT-qPCR gene expression analysis of our cell lines, confirming the differential status of multiple genes while uncovering the new ones. We anticipate that our panels of cell lines will be useful not only for studying RDEB signatures but also for investigating the overall mechanisms involved in disease progression.
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