Investigation of climate change and history of lead deposition using soil archives

Our study focused on the investigation of climate change and the fate of lead in soils from the Low Volga region of Russia over 3500 years. We used a comparative analysis of the modern soils and palaeosols preserved under burial mounds, which date back to the Middle Ages and the Early Iron and Bronze Ages. A climate reconstruction showed periodic changes, with the most humid climate conditions occurring during Golden Horde period. However, we could not find any consistent changes in Pb concentration and profile distribution following the climate change. We observed a clear difference in Pb isotopic ratios between the lower and upper horizons both for the modern and buried profiles, reflecting the influence of atmospheric lead depositions. However, there is no statistically significant difference in Pb isotopic ratios between the upper horizons of buried and modern soils (except modern soils collected in the vicinity of a motorway). This means that either anthropogenic input due to long range air transport was insignificant, or that airborne anthropogenic lead and natural airborne lead have similar isotopic composition

Spectroscopic investigation of the spatiotemporal dynamics of an electric field in plasma of a beam-type high-voltage discharge in helium

In the present work, a method of determining the spatiotemporal characteristics of the electric field strength in an accelerating gap and a plasma flare of a beam-type high-voltage pulsed discharge in He at moderate pressure is presented. The method is based on spectroscopic data on the Stark splitting of π-components of He 2P–4Q transitions; Q = D(4921.93 Å), F(4920.35 Å) in the near-cathode region of the discharge and on the spatiotemporal characteristics of intensities of He(2s1S–3p1P0) spectral lines with λ = 5015 Å and He+(3d–4f) spectral lines with λ = 4685 Å measured experimentally and calculated from the data of statistical simulation of the electron kinetics by the Monte Carlo method. The shape and strength of the electric field of the space charge in the interelectrode gap and the drift region of the discharge are estimated. It is demonstrated that the electric field created by the current pulse of uncompensated space charge in the near-anode region changes the discharge regime and causes degradation of the electron beam in the plasma flare. It is established that the flux of secondary electrons from the drift region to the anode has significant effect on the radiation intensity distribution in this region of the discharge

Generating low-temperature glow discharge plasma in the atmospheric pressure helium after spark breakdown: Modelling plasma with the prescribed properties for biomedical applications

This paper concerns computational modelling of the low-temperature glow discharge plasma in the atmospheric pressure helium after spark breakdown and research on the dependence of a spatial distribution of plasma on the initial conditions of discharge and parameters of the external electric circuit. This study analysed the influence of the initial distribution of a space charge on the generation of the glow discharge plasma after the spark breakdown between flat electrodes by means of a 2D-axial symmetric model of the atmospheric pressure helium plasma in the drift-diffusion approximation. With the discharge current of 1–12 mA, the solution for a quasi-steady state of plasma is obtained. The dependence of a type of this discharge mode on the parameters of the external electric circuit and coefficient of the secondary cathode emission is studied

TO THE QUESTION OF FLUORINE REGENERATION FROM GAS-CLEANING SOLUTIONS OF ALUMINUM PRODUCTION

The paper presents a new approach to the processing of gas cleaning solutions of aluminum production. The technology of electrochemical purification of solutions was developed and proposed for consideration in order to reduce the environmental impact, regenerate cryolite, and obtain commercial sodium sulfate.В работе изложен новый подход к переработке растворов газоочистки алюминиевого производства. Разработана и предложена к рассмотрению технология электрохимической очистки растворов с целью снижения воздействия на окружающую среду, регенерации криолита, получения товарного сульфата натрия

MORPHOGENESIS OF KNEE HYALINE CARTILAGE DURING INTRAARTICULAR INJECTION OF PLATELET-RICH AUTOLOGOUS PLASMA AND/OR HYALURONIC ACID PREPARATION IN RATS WITH EXPERIMENTAL OSTEOARTHRITIS

According to current concepts, the influence of autologous platelet-rich plasma (PRP) and high molecular hyaluronates (HA) on the repair of hyaline cartilage during its inflammatory and degenerative changes has been insufficiently studied yet. The objective of the work was to evaluate the morphological changes in the structure of hyaline cartilage in experimental osteoarthritis after intra-articular injection of PRP and/or HA. Material and methods. The authors used 50 adult rats of Wistar line, weighing 250±2,2 g., distributed into five groups of 10 animals (two control and three experimental groups). An experimental gonarthosis was simulated on four groups of animals. Animals of the first experimental group received intra-articular injection of PRP, the second group – HA, the third – both PRP and HA. Results. No morphological signs of degenerative and inflammatory changes in the first control group were identified. Following osteoarthritis simulation the articular cartilage thinned to 121±20,4 microns (p<0,05) and the volume fraction of chondrocyte decreased to 1,2±0,6% (p<0,05). The authors observed an uneven coloration of collagen fibers with severe tinctorial properties disorder of the articular cartilage matrix. After the RPR introduction the authors observed tickening of the articular cartilage up to 275±18,9 micron (p<0,05) and the volume fraction of chondrocytes up to 18,4±2,0% (p<0,05). The contour of the cartilage surface became smoother with the formation of a cell-free zone. Collagen fibers demonstrated a uniform distribution, tinctorial properties of cartilage matrix in all areas were preserved, no signs of inflammation were noted. After HA introduction the authors observed thickening of the cartilage plate up to 264±21,3 microns (p<0,05) and the volume fraction of chondrocytes up to 11,6±1,2% (p<0,05). The surface of the cartilage featured uneven contours due to multiple areas of pulping. Uneven tinctorial properties of cartilage matrix, thickness and orientation of collagen fibres were retained. No signes of inflammation were observed. After the combined consecutive application of PRP and HA cartilage thickness increased up to 268±15,3 microns (p<0,05) and the volume fraction of chondrocytes increased up to 12,7±0,9% (p<0,05). Individual portions of pulping on the cartilage surface were observed. Tinctorial properties of the cartilage matrix were preserved; the focal uneven staining of collagen fibers in the basal zone was observed. No signs of inflammation were noted. Conclusion. During osteoarthritis simulation in knee joints of experimental Wistar line rats the authors observed severe structural changes in articular hyaline cartilage including complete destruction accompanied by vascular proliferation and granulomatous inflammation. Intraarticular injections of PRP, HA as well as PRP in combination with HA during the simulation of osteoarthrosis were accompanied by a decrease in the severity of degenerative and dystrophic processes and improval of tinctorial properties of articular cartilage matrix. Sole application of PRP or consecutive application of PRP followed by HA were observed as having the more significant reparative effect on articular cartilage as compared to HA

Supersymmetry of Tensionless Rotating Strings in AdS_5 x S^5, and Nearly-BPS Operators

It is shown that a class of rotating strings in AdS_5 x S^5 with SO(6) angular momenta (J,J',J') preserve 1/8-supersymmetry for large J,J', in which limit they are effectively tensionless; when J=0, supersymmetry is enhanced to 1/4. These results imply that recent checks of the AdS/CFT correspondence actually test a nearly-BPS sector.Comment: 12 pages, no figures; v2: new section on CFT operators and new references added, discussion section and acknowledgements modified, abstract rephrashe

Lead content and isotopic composition in submound and recent soils of the Volga upland

Literature data on the historical reconstructions of the atmospheric lead deposition in Europe and the isotopic composition of the ores that are potential sources of the anthropogenic lead in the atmospheric deposition in the lower Volga steppes during different time periods have been compiled. The effect of the increasing anthropogenic lead deposition recorded since the Bronze Age on the level of soil contamination has been investigated. For the first time paleosol buried under a burial mound of the Bronze Age has been used as a reference point to assess of the current contamination level. The contents and isotopic compositions of the mobile and total lead have been determined in submound paleosols of different ages and their recent remote and roadside analogues. An increase in the content and fraction of the mobile lead and a shift of its isotopic composition toward less radiogenic values (typical for lead from the recent anthropogenic sources) has been revealed when going from a Bronze-Age paleosol to a recent soil. In the Bronze-Age soil, the isotopic composition of the mobile lead is inherited from the parent rock to a greater extent than in the modern soils, where the lead is enriched with the less radiogenic component. The effect of the anthropogenic component is traced in the analysis of the mobile lead, but it is barely visible for the total lead. An exception is provided by the recent roadside soils characterized by increased contents and the significantly less radiogenic isotopic composition of the mobile and total lead

IMPLEMENTATION OF A HIGH-EFFICIENT ELEMENTARY HEATER IN THE CIRCUIT OF AN EXISTING EVAPORATOR WITH THE PURPOSE OF SAVING HEATING STEAM

he paper gives a brief description of the method for producing alumina (Al2O3) by the Bayer method.This work was supported by the Russian Foundation for Basic Research (grant # 19-53-55002)