Energy Gap Induced by Impurity Scattering: New Phase Transition in Anisotropic Superconductors

It is shown that layered superconductors are subjected to a phase transition at zero temperature provided the order parameter (OP) reverses its sign on the Fermi-surface but its angular average is finite. The transition is regulated by an elastic impurity scattering rate $1/\tau$. The excitation energy spectrum, being gapless at the low level of scattering, develops a gap as soon as the scattering rate exceeds some critical value of $1/\tau_\star$.Comment: Revtex, 11 page

Thermodynamics of Two - Band Superconductors: The Case of MgB2_{2}

Thermodynamic properties of the multiband superconductor MgB$_{2}$ have often been described using a simple sum of the standard BCS expressions corresponding to $\sigma$- and $\pi$-bands. Although, it is \textit{a priori} not clear if this approach is working always adequately, in particular in cases of strong interband scattering. Here we compare the often used approach of a sum of two independent bands using BCS-like $\alpha$-model expressions for the specific heat, entropy and free energy to the solution of the full Eliashberg equations. The superconducting energy gaps, the free energy, the entropy and the heat capacity for varying interband scattering rates are calculated within the framework of two-band Eliashberg theory. We obtain good agreement between the phenomenological two-band $\alpha$-model with the Eliashberg results, which delivers for the first time the theoretical verification to use the $\alpha$-model as a useful tool for a reliable analysis of heat capacity data. For the thermodynamic potential and the entropy we demonstrate that only the sum over the contributions of the two bands has physical meaning.Comment: 27 pages, 10 figures, 1 table, submitted to Phys. Rev.

The gas of elastic quantum strings in 2+1 dimensions: finite temperatures

The finite temperature physics of the gas of elastic quantum strings as introduced in J. Zaanen, Phys. Rev. Lett. 84, 753 is investigated. This model is inspired on the stripes in the high Tc superconductors. We analyze in detail how the kinetic interactions of the zero temperature quantum problem crossover into the entropic interactions of the high temperature limit.Comment: 14 pages, 2 figure

Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire : an expert assessment

As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%-85% of permafrost carbon release can still be avoided if human emissions are actively reduced.Peer reviewe

Modeling of permafrost and gas hydrate stability zone within Alaskan Arctic shelves and continental margins

Thesis (M.S.) University of Alaska Fairbanks, 2003A mathematical model was used to determine the behavior of the thermal regime and temperature and pressure conditions due to climate and sea level variations of the gas hydrate stability zone formation at four sites within the Alaskan Arctic Shelf. Two soil types, coarse-grained and fine-grained, and three types of programs were used. The programs were distinguished by whether or not they took unfrozen water and latent heat into account. Simulations suggest the presence of subsea permafrost in a vast area of shelf near Prudhoe Bay. Near Barrow and Lonely subsea permafrost extends up to several tens of kilometers offshore, while subsea permafrost near Cape Thompson almost completely disappeared during the last marine transgression. Distribution of subsea permafrost varies with soil type, thermal properties and geothermal heat flow. The possible presence of methane gases in a pore space of the material influences the thermal regime and permafrost distribution. Simulations indicate that a Gas Hydrate Stability Zone can exist at depths from 220 m to 1100 m. Possible formation and presence of gas hydrates in the sediments changes the thermal regime significantly; therefore the shape of subsea permafrost depends on whether or not gases are present in the sediments

Matrix Metalloproteinase 9 as a Predictor of Coronary Atherosclerotic Plaque Instability in Stable Coronary Heart Disease Patients with Elevated Lipoprotein(a) Levels

We sought to investigate whether levels of matrix metalloproteinases (MMPs) and their inhibitors predict coronary atherosclerotic plaque instability, as assessed by intravascular ultrasound (IVUS) virtual histology during coronary angiography. Blood samples were collected before angiography in 32 subjects (mean age 56 ± 8 years) with stable coronary heart disease (CHD) and elevated lipoprotein(a) (Lp(a), 94 ± 35 mg/dL). Levels of high-sensitivity C-reactive protein (hsCRP), apolipoprotein B100 (apoB100), MMP-7, MMP-9, tissue inhibitor of metalloproteinases (TIMP)-1, and TIMP-2 were determined using commercially available enzyme-linked immunosorbent assay kits. Results. The morphology of a total of sixty coronary lesions was assessed by virtual histology IVUS imaging. Eleven (18%) plaques in nine (28%) patients were classified as plaques with an unstable phenotype or a thin-cap fibroatheroma. Age, low-density lipoprotein cholesterol, apoB100, MMP-7, and MMP-9 levels were positively associated with necrotic core volume. Conversely, there was a negative relationship between MMP-7 and -9 levels and fibrous and fibro-fatty tissue volume. Multivariate regression analysis revealed that MMP-9 is a strong independent predictor of atherosclerotic plaque instability in stable CHD patients. In stable CHD patients with elevated Lp(a), MMP-9 levels are positively associated with the size of the necrotic core of coronary atherosclerotic plaques

PHOTOCHEMICAL TRANSFORMATION OF DISSOLVED ORGANIC MATTER AND BEHAVIOR OF METALS IN THE WATERS OF THE SOUTHERN TAIGA BOG COMPLEX, WESTERN SIBERIA

Link for citation: Raudina T.V., Smirnov S.V., Istigechev G.I., Pokrovsky O.S. Photochemical transformation of dissolved organic matter and behavior of metals in the waters of the southern taiga bog complex, Western Siberia. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 9, рр. 182-193. In Rus. The relevance. Dissolved organic matter is one of the largest biologically available sources of carbon in terrestrial and aquatic ecosystems, and its dynamics are critical to local and global carbon cycles. Destruction of organic matter during migration determines the biological cycle of elements and their stability. Important processes that lead to the transformation or removal of the dissolved organic matter are bio- and photodegradation. To date, enough research has been carried out to study the composition of humic substances, forms of metals, and the processes of migration of organo-mineral compounds in natural waters of the taiga zone, Western Siberia. Work is underway to study the dissolved organic carbon bioavailability, but the mechanisms of its photochemical transformations in different seasons of the year have not been studied. At the same time, photochemical mineralization of dissolved organic compounds largely regulates the biogeochemical cycles of elements by changing their bioavailability, the intensity of carbon dioxide emission from surface waters into the atmosphere, and the removal of dissolved trace elements through precipitation and coagulation. The main aim is to assess changes in the chemical composition and the rate of the dissolved organic matter and dissolved metals removal in the waters of the southern taiga bog complex (Western Siberia) under the sunlight exposure on a spatio-temporal scale. Objects: soil waters within different bog landscapes (open sedge-sphagnum fen, tall ryam (pine-shrub-sphagnum phytocenosis with high pine trees), and waterlogged mixed forest) of the Bakchar bog complex located in the southeastern part of the Ob-Irtysh interfluves, the Vasyugan plain. The waters were taken at a depth by digging a pit (40´40 cm area, 40 cm depth), which allowed the surrounding gravitational water to fill it up to the depth of 10–20 cm. The sampling took place during two field period in 2020 (June and October). Methods. pH, water temperature, specific conductivity (Cond) and dissolved oxygen were measured using a multiparameter instrument (WTW MULTI 3430 SET). The dissolved organic carbon was measured by a high-temperature thermic oxidation method using a Shimadzu TOC-LCPN analyzer, with an uncertainty of 2 %. The absorbance was measured at wavelengths up to 800 nm, 1 nm step using quartz 10 mm cuvette on a Cary-50 spectrophotometer. Major cations (Ca, Mg, Na, K), Si, and trace metals were determined with an ICP-MS Agilent CE 7500 with In and Re as internal standards and three various external ones. In the photodegradation experimental design, we followed the methodology which is sunlight exposure of sterile filtered (0,2 μm) samples in quartz reactors in the outdoor pool. Results. The authors revealed the influence of photodegradation on the qualitative and quantitative composition of dissolved organic substances and the behavior of metals in water samples of bog landscapes of the taiga zone of Western Siberia on spatiotemporal scales. It was established that from 3 to 30 % of the dissolved organic carbon can be removed from soil water under the influence of sunlight with maximum values in early June. At the same time, in autumn, despite the decrease in the amount of solar radiation, the photodegradable DOC can also reach 10–12 %. In general, there is a decrease in the percentage of the dissolved organic carbon loss in the waters in the row fen>ryam>forest. The dissolved organic carbon removal can be associated both with the transition of a part into an inorganic form, and with the destruction of high-molecular organic substances. A significant change (p<0.05) in the optical parameters is noted, which is consistent with the behavior of the dissolved organic matter during photolysis. In addition, under the influence of insolation, the transformation of organo-mineral compounds occurs, which leads to a change in the forms of metals. The greatest losses relative to control were observed for rare earth elements (Y, La, Ce, Pr, Nd), as well as Ti, V, which in some cases reach 70 % (more significant in fen waters). These trace elements show behavior similar to dissolved organic carbon,  Al and Fe, which confirms the importance of organic and organo-Fe-Al-colloids determining the behavior of most elements in acidic waters with a high content of organic matter

Lipoprotein(a) and Cardiovascular Outcomes after Revascularization of Carotid and Lower Limbs Arteries

Background: Despite high-intensity lipid-lowering therapy, there is a residual risk of cardiovascular events that could be associated with lipoprotein(a) (Lp(a)). It has been shown that there is an association between elevated Lp(a) level and cardiovascular outcomes in patients with coronary heart disease. Data about the role of Lp(a) in the development of cardiovascular events after peripheral revascularization are scarce. Purpose: To evaluate the relationship of Lp(a) level with cardiovascular outcomes after revascularization of carotid and lower limbs arteries. Methods: The study included 258 patients (209 men, mean age 67 years) with severe carotid and/or lower extremity artery disease, who underwent successful elective peripheral revascularization. The primary endpoint was the composite of nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death. The secondary endpoint was the composite of primary endpoint and repeated revascularization. Results: For 36-month follow-up, 29 (11%) primary and 128 (50%) secondary endpoints were registered. There was a greater risk of primary (21 (8%) vs. 8 (3%); hazard ratio (HR), 3.0; 95% confidence interval (CI) 1.5–6.3; p &lt; 0.01) and secondary endpoints (83 (32%) vs. 45 (17%), HR, 2.8; 95% CI 2.0–4.0; p &lt; 0.01) in patients with elevated Lp(a) level (≥30 mg/dL) compared to patients with Lp(a) &lt; 30 mg/dL. Multivariable-adjusted Cox regression analysis revealed that Lp(a) was independently associated with the incidence of cardiovascular outcomes. Conclusions: Patients with peripheral artery diseases have a high risk of cardiovascular events. Lp(a) level above 30 mg/dL is significantly and independently associated with cardiovascular events during 3-year follow-up after revascularization of carotid and lower limbs arteries