Changes in the macro-, meso-, and micromorphological properties of plowed migration-mycelial chernozems (Haplic Chernozems) after their conversion into permanent unmanaged fallow state are discussed. ...The research objects are located in Kursk oblast. The results of the study indicate that changes in the soil morphology are most pronounced in the plow and carbonate-accumulative horizons. As a result of self-restoration processes, the structure of plow horizons improves, and their color becomes darker. Cracks formed as a result of seasonal soil drying disappear, and the structural degradation of plowed soils is stopped. Hard carbonate nodules formed in deep horizons of plowed soils due to seepage and stagnation of moisture in cracks in the periods of bare land disappear over 25–50 years of fallowing. Transitional forms—relatively soft calcareous nodules (beloglazka, white eyes) with a hard core—may be formed. Upon the uptake of soil solutions by roots, the accumulation of carbonates in the form of fibrous calcite takes place in the humus-containing material around the roots. Carbonate incrustations consisting of fibrous calcite are seen along cracks in plowed soils and in young fallows and are thin and fragmentary in the soils of old fallows and in virgin chernozem. The results of the studies of chronosequences of fallowed soils in Belgorod, Rostov, Lipetsk, and Kursk oblasts are generalized. The main features of transformation of the carbonate status of fallow soils are specified: (a) disappearance of hard carbonate pedofeatures in the lower soil horizons, (b) lowering of the lines of effervescence, and (c) a general decrease in the content and total pool of carbonate carbon. The change in the humus state of fallowed soils after the end of plowing are differently directed: the content of stock of humus decrease in gray soils (Phaeozems) and increase in chernozems and dark gray soils.
The postagrogenic dynamics of organic carbon (C
org
), total nitrogen (N
tot
), and density fractions of organic matter (OM) in the dark gray soil (Haplic Phaeozem, Belgorod oblast, Les na Vorskle ...(Forest on Vorskla) Reserve) and migrational–mycellary Chernozem (Haplic Chernozem, Kursk oblast, Streletskaya Steppe Reserve) were examined. The most significant postagrogenic changes in all the studied soil properties were observed in the top 0–5 cm layer. The contents of C
org
and N
tot
in this layer of the Phaeozem chronosequence increased by 1.2–1.3 times over 45 years after cessation of farming. The contents of C
org
and N
tot
in the top 0–5 cm layer of Chernozem chronosequence increased by 1.9–2.0 times over 60 years of the postagrogenic development. The accumulation of C
org
took place in all density fractions. In both chronosequences, the free fraction of organic matter (density <1.6 g cm
–3
) increased, while the occluded fraction (density <2.0 g cm
–3
) virtually did not change. In 60 years after the cessation of farming on Chernozem, all the studied parameters became close to those in the Chernozem under natural steppe. In the Phaeozem, these parameters recovered by no more than 60% of the level typical for the natural soil over 45 years after the cessation of farming. Thus, the postagrogenic restoration of organic matter and all its fractions in the forest-steppe zone was much faster in the Chernozem in comparison with the Phaeozem.
The Skyline of Paleopedology Makeev, A.O.; Rusakov, A. V.
Moscow University soil science bulletin,
2023/12, Letnik:
78, Številka:
4
Journal Article
Recenzirano
Paleopedology is a booming scientific discipline that studies the soils of the past geological epochs in order to assess the paleoenvironmental evolution. The scope of paleosol studies embraces not ...only soils themselves, but also the products of their involvement in biogeosphere cycles. This ensures the planetary role of pedogenesis, which includes the transformation of the upper layers of the lithosphere leading to the increase in fine earth, formation of new minerals, and residual or accumulative concentration of elements. In the geological history of the Earth, pedogenesis is realized within the framework of exogenesis, which includes weathering, soil formation, sedimentation, diagenesis, and geochemical migration. The pedolithosphere records the critical points in the landscape evolution of the Earth from the very onset of the geological record, including the oxygenation of the atmosphere, the emergence of the higher plants and herbaceous biomes, the dynamics of Interglacial–Glacial cycles, etc. Paleosols are the base for paleogeographic reconstructions and predictive models of the future climate change. Paleopedology expands the horizons of soil science within the system of biogeosphere sciences and determines the development of new scientific disciplines—bacterial paleontology, paleogeochemistry, biogeomorphology, astropedology, geoarchaeology, ecological paleopedology, soil paleocryogenesis and cryobiosphere studies. The historical dimension granted by paleopedology makes pedology a mature historical science.
To present modern aspects of improving surgical techniques in tracheal resection developed in recent years.
The authors have the most extensive experience in tracheal surgery (>2.000 patients over ...the past 50 years). Diagnostic capabilities, perioperative management and surgical techniques have changed over such a long period. This concerns the proposed classification of cicatricial tracheal stenosis, features of endoscopic and X-ray diagnostics, indications for various surgeries, choice of surgical approach, technique of tracheal tube mobilization and anastomosis after tracheal excision. Preventive measures for severe postoperative complications are described.
Such an extensive experience allowed the authors to develop an algorithm for the treatment of patients with tracheal stenosis. This significantly reduced the incidence of postoperative complications and mortality. Replication of such equipment is associated with technical support of hospitals and professional level of specialists consisting of endoscopist, anesthesiologist, intensive care specialist and thoracic surgeon.
Introduction
.
The article is devoted to the issues of non-destructive testing of mechanical characteristics of metal structural elements of cranes. The reliability of cranes largely determines their ...safety. The main manifestations of operational failures of floating cranes are analyzed on the example of the UMK-2 crane. It is noted that 27% of failures occur due to the loss of metal strength of their structural elements. Determination of the causes of such failures is possible by conducting non-destructive testing of the mechanical characteristics of the failing structural elements metal. The paper provides the principle of one of the methods of non-destructive strength control based on the impact insertion of a conical indenter into the metal under study with the subsequent analysis of the intermediate parameters of this insertion. The results of measurements of the mechanical characteristics of the metal deformed during the operation of the boom strut of a floating crane are given. The current measured values of the mechanical characteristics of the metal obtained at various points of the strut are processed for compliance with the three-parameter Weibull law to obtain the minimum values of these characteristics. As a result of such processing, it is stated that the minimum values of yield strength, strength and elongation are lower than those claimed by the design documentation for the crane. This may be one of the reasons for the deformation of the structural element during operation.
Problem Statement
.
The application of the method of non-destructive testing of the metal of the boom strut is considered in order to assess the mechanical characteristics and establish possible causes of its deformation when analyzing the operational reliability of the crane.
Theoretical Part
.
When identifying possible causes of deformation or destruction of steel elements of crane structures, it is proposed to apply a method of non-destructive testing of mechanical characteristics based on the impact insertion of a conical indenter into the test surface. Further, it is proposed to process the obtained sample of values of the measured characteristic for compliance with the three-parameter Weibull law to estimate the shift parameter or the minimum value of this characteristic.
Conclusions
.
The minimum values of the tensile strength, yield strength and relative elongation of the metal of the deformed boom strut of the UMK-2 crane were obtained on the basis of the application of the method of non-destructive testing with subsequent approximation of statistical information by the Weibull distribution law. A conclusion was made about the reduced strength characteristics of the metal relative to those stated in the technical documentation, which could cause deformation of the crane boom element.
The selection of rootstocks is one of the first and most important stages in the establishment of grape plantations under grafted conditions, which determines the productivity of rootstock-scion ...combinations and the further chain of design solutions: spatial placement of rows on the land plot, accompanying the production process of agronomic and agrochemical methods. Given the high importance of terroir factors for viticulture and winemaking, we were aware of the need to consider them in detail at this design stage. The aim was to create an algorithm for selecting varieties based on local terroir factors and apply it to the design of vineyards. Based on the analysis of literary sources and the agronomic experience of viticulture and winemaking specialists, we have identified key stress factors that in general, should be taken into account when selecting varieties of rootstocks. Based on the results of a comprehensive study of terroir and analytical diagnostics of soil samples taken on a land plot located in the Bakhchisaray district of the Republic of Crimea, local stress factors representing risks were clarified and prioritized neo-medially at the site of testing the landscape-adapted approach to the selection of rootstocks: carbonate condition, risk of phylloxera infestation, high content of fine fractions in granulometric composition, short-term droughts, risk of local overwatering, phosphorus deficiency. In total 20 the most common commercial varieties of rootstocks were considered for each selected soil area. The sample reduction scenario, based on the prioritization of the above stressors, reduced the number of varieties considered to three variants: 1103 Paulsen, 140 Ruggeri, and Fercal, which were scored against each other and considering the local terroir conditions of the plot, for further comparison in terms of market and logistics in making the final design decision.
We have studied manganese-containing calcium phosphates differing in manganese content and phase composition. At a manganese content of 0.15 wt %, the whitlockite content is ~90 wt % and the calcium ...pyrophosphate content is ~10 wt %. Increasing the manganese content to 1.49 wt % reduces the whitlockite content to ~70 wt % and increases the calcium pyrophosphate content to ~30 wt %. IR spectroscopy results show that the samples calcined at 400°C have the apatite structure, whereas raising the calcination temperature to 900°C leads to the formation of the whitlockite structure and calcium pyrophosphate. Active sintering begins in the range 920–1050°C. Raising the firing temperature to 1200°C leads to the formation of a densely sintered structure, with melted regions and an average grain size from 15 to 25 μm. With increasing manganese content, the grain size of the ceramics decreases. Our results on cytotoxic properties demonstrate that the samples are not cytotoxic and maintain cell proliferation and spreading. The cytotoxicity of the samples is insensitive to the calcium pyrophosphate and manganese concentrations. The powders and ceramics prepared in this study can be used as key components of novel materials for bone tissue engineering.
Over the last 30-40 years, climate changes have resulted in environmental changes within the Upper Volga basin. In this study, an attempt to analyze the soil record of recent climate changes was ...made. An example of soil evolution induced by climate change was studied on hydromorphic saline soils in the nature reserve of the Varnicy Saline Spring. In a humid climate, soil salinization occurring in discharge areas can quickly change in response to the changed hydrothermal regime because of close relationships between climatic conditions and groundwater systems. In a poorly drained depression, we could observe an increasing soil salinity and developing hydrogenic accumulation of salts, whereas the groundwater salinity was stable.
The soils buried under the early medieval mounds of the 9th and early 11th centuries AD were studied. The reconstruction of environmental trendу and their influence on soils was carried out on the ...basis of a comparative analysis of the properties of soils buried under mounds of different ages, surface soils, and newly formed soil on mound structures supplemented with data on the time of soil formation on sandy parent rocks in the taiga zone. The study area belongs to the Baltic province of soddy-podzolic soils of the southern taiga subzone. Soils buried under mound structures characterize periods with different climatic conditions. Soils that developed before burial in the cool and humid climate of the 8th–9th centuries AD are specified by the mobility of iron compounds in the profile and a morphologically pronounced accumulation of bleached quartz grains in its upper part. The influence of relatively warm and dry climate of the 10th century AD on the processes of soil formation is manifested in the lower mobility of iron compounds, more active humus accumulation, and less pronounced bleaching of mineral grains. The time of formation of the profile of soddy podbur in the material of mound structures was estimated at 1000 years. The construction of the mound structures consisted in successive filling of the mound from the edges to the center of the site, so that the material of middle horizons of the initial natural soil turned out to be in the upper part of the mound.
Rock freezing affects soil complexes with maximum temperature gradients and forms a set of the specific cryotrasologic features in a solid matrix of soils. Remaining unchanged, these features serve ...as direct and indirect indicators of the past cryogenic settings. Transformation of the soil mass at the macro- and micromorphological levels is related to the direct indicators. Soil gleyzation in the drained positions is conditioned by the occurrence of frozen aquicludes in past settings; it is related to indirect indicators. We revealed the complex of such features in paleosols to the north of the European and Western Siberian Loess Belt and used them to estimate the cryogenic settings of the Late Pleistocene.
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