bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolution of the soil water retention curve based on plastic volumetric strain
Authors: Kodikara J. , Jayasundara C.
Published: October 2020

The water retention behaviour of soil can be defined as the relationship between the degree of saturation (or water content) and suction at a constant temperature, which characterises the hydraulic behaviour of unsaturated soils, normally represented as the soil water retention curve (SWRC). The SWRC is commonly measured at nominal net stress by initially saturating a soil specimen and then subjecting it to drying and wetting paths, resulting in major drying and wetting curves. However, there is evidence that during these major drying and wetting paths and initial saturation, soil can undergo volumetric deformation with changes in void ratio, sometimes plastically. Therefore, for coupling the SWRC with mechanical behaviour, the dependency of SWRC on other state variables such as void ratio has been proposed. In this paper, an approach to defining SWRC for a particular plastic volumetric strain is presented within the generalised MPK model. The SWRC evolves as soil is subjected to wet/dry cycles, eventually approaching drying and wetting curves relevant to an environmentally-stabilised state. The performance of this model is demonstrated by the simulation of the loading/unloading/drying/wetting paths followed in a laboratory experiment. In addition, the evolution of the commonly-considered major drying and wetting curves is simulated, highlighting key features of the environmentally-stabilised line..
A frost heave model of unsaturated coarse-grained soil considering vapour transfer
Authors: Liu Jianlong , Teng Jidong , Zhang Sheng , Sheng Daichao
Published: October 2020

Substantial frost heave has been observed in coarse fills in high-speed railway embankments. These coarse fills have low fine contents and very low water content. The groundwater table is located below the coarse fills. The coarse fills were considered not susceptible to frost heave. Recent experimental results in the literature showed that vapour transfer has a considerable influence on the frost heaving of unsaturated coarse-grained soil. But vapour transfer has been rarely considered in the modelling of frost heave. This study presents a new frost heave model with considering vapour transfer and its contribution to ice formation. The rigid ice theory is applied to initiate an ice lens formation in the frozen fringe. An updated computer programme PCHeave is developed by considering the vapour transfer. The results of the proposed model are compared with laboratory test results, which show reasonable agreement. The prediction of the model agrees well with the measured frost heave and frost depth, which indicates that the proposed model can reasonably reflects the process of frost heave in unsaturated coarse soil.
A semi-empirical model to predict excess pore pressure generation in partially saturated sand
Authors: Sayedmasoud Mousavi , Ghayoomi Majid
Published: October 2020

Past studies revealed that excess pore pressure generation due to cyclic loading is highly governed by induced strains, volumetric deformation potential of soil, number of cycles, and bulk stiffness of pore fluid. It is well established that partial saturation can significantly reduce bulk stiffness of pore fluid and consequently excess pore pressure generation during seismic loading. On the basis of that, a number of researchers have investigated induced partial saturation as an effective soil improvement technique to increase the liquefaction resistance of fully saturated soils. This paper focuses on development of a semi- empirical model to interpret the effects of partial saturation on the excess pore pressure generation in sands. In this regard, an existing strain based excess pore pressure ratio (ru) prediction model originally developed for fully saturated soils was modified to incorporate the effect of partial saturation on the excess pore pressure generation. The literature data as well as data from a series of strain-controlled direct simple shear test were used to evaluate the reliability of the proposed equation in predicting the excess pore pressure ratio in partial saturation condition.
Water-entry pressure in water repellent soils: a review
Authors: Xing Xin , Lourenço Sérgio D.N.
Published: October 2020

Water repellent soils can be naturally promoted (e.g. after wildfires) or synthetically induced by mixing with hydrophobic compounds (e.g. polydimethylsiloxane). The study of soil water repellency has lasted for over one century which implied the significant effect of soil water repellency on water infiltration, evaporation, soil strength, and soil stability. Water repellent soils can also be exploited by geotechnical engineers to offer novel and economical solutions for ground infrastructure. This paper synthesizes different methods for assessing soil water repellency based on varied indexes (e.g. contact angle, time for a drop to infiltrate) and with a focus on water entry pressure. Measurements of these parameters in synthetic water- repellent sands were taken, some results of which are summarized with discussion of key factors affecting water repellency. A comparison of these methods shows that water entry pressure can be more representative for assessing the water repellency of bulk samples.
Water retention and shrinkage curves of weathered pyroclastic soil
Authors: Dias Ana Sofia , Kamath Abhijith , Pirone Marianna , Urciuoli Gianfranco
Published: October 2020

The modelling of the triggering mechanism of rainfall-induced landslides in slopes covered by pyroclastic soil (as the area surrounding Mount Vesuvius in Campania, Italy) requires the hydraulic characterization of soil in unsaturated conditions in order to analyse the slope response to rainfalls. In previous studies carried out on Campanian pyroclastic soils, the volumetric soil changes due to suction changes have been disregarded, being them negligible in soils characterized by low plasticity and low clay contents. However, a more accurate determination of the water retention curve (WRC) in terms of volumetric water content requires a correct estimation of the total soil volume, which is affected by the soil stress-state. The proper approach would require the estimation of both WRC in terms of gravimetric water content and the shrinkage curve (SC). In the present study, a relation between void ratio and suction was determined for a pyroclastic soil sampled at Mount Faito in Southern Italy. Therefore, a correction of the volumetric water content was carried out resulting in updated water retention curves. Here, the matric suction was the only factor affecting the stress-state of the soil.
The influence of rates of drying and wetting on measurements of soil water retention curves
Authors: Azizi Arash , Kumar Ashutosh , Lingwanda Mwajuma Ibrahim , Toll David Geoffrey
Published: October 2020

The water retention curve is fundamental for a comprehensive description of the hydro-mechanical behaviour of unsaturated soils. The water retention testing system developed at Durham University allows direct and continuous measurement of suction using a high capacity tensiometer, water content determined from mass readings of a digital balance and measurements of volume change. The system was modified to accommodate an additional tensiometer to measure suction at the top besides the existing one at the bottom of the soil specimen. Soil specimens were subjected to drying and wetting following two procedures: discrete measurements carried out in stages to ensure equalisation and continuous measurement at different rates. All suctions measured during continuous and discrete measurements were very close at high saturation degrees. At lower saturation degrees, the suction values from the top and bottom of the specimen deviated from suctions observed in discrete measurements. This deviation in suction values was more evident in accelerated drying and wetting patterns. This can be explained by the fact that water permeability reduces with the decrease in saturation levels.
An estimation of the soil water characteristics curves of Trinidad's expansive clays
Authors: V A Alexander Damian , Ho Park Kyung , Anthony Gay Derek
Published: October 2020

Volume change behaviour of expansive clays has been one of the leading causes of damage to civil infrastructures worldwide. Contributing factors that lead to failures relate to changes in water content within the soil. Variations of water content can vary significantly based on an area’s climate regime. Trinidad has two seasons, the dry season (January to June) and the wet season (July to December). This variation leads to volume changes of expansive clay, where they exist mainly within the central and south regions of Trinidad. These areas are densely populated by residential and commercial buildings, which can be susceptible to damages from unsaturated expansive clays. The Soil Water Characteristic Curve (SWCC) for expansive clays is critical to estimate their unsaturated properties for the analysis of water flow movement. This study investigates the SWCCs for two expansive clay soil types in Trinidad. A WP4-T (Water Potential Measurement) is used to measure soil suction. The shrinkage curve (SC) test is conducted to consider the volume change of soil. The Fredlund and Xing (1994) SWCC equation and Fredlund and Zhang (2013) SC equation are used to fit the measured data. The SWCCs in terms of gravimetric and volumetric water contents and degree of saturation are compared. It is found that the normalised degree of saturation SWCC can provide a better display of the SWCC and estimation of the air-entry value.
Measurement of xylem water pressure using High-Capacity Tensiometer and benchmarking against Pressure Chamber and Thermocouple Psychrometer
Authors: Dainese Roberta , Tedeschi Giuseppe , Fourcaud Thierry , Tarantino Alessandro
Published: October 2020

The response of the shallow portion of the ground (vadose zone) and of earth structures is affected by the interaction with the atmosphere. Rainwater infiltration and evapotranspiration affect the stability of man-made and natural slopes and cause shallow foundations and embankments to settle and heave. Very frequently, the ground surface is covered by vegetation and, as a result, transpiration plays a major role in ground-atmosphere interaction. The soil, the plant, and the atmosphere form a continuous hydraulic system, which is referred to as Soil-Plant-Atmosphere Continuum (SPAC). The SPAC actually represents the ‘boundary condition’ of the geotechnical water flow problem. Water flow in soil and plant takes place because of gradients in hydraulic head triggered by the negative water pressure (water tension) generated in the leaf stomata. To study the response of the SPAC, (negative) water pressure needs to be measured not only in the soil but also in the plant. The paper presents a novel technique to measure the xylem water pressure based on the use of the High-Capacity Tensiometer (HCT), which is benchmarked against conventional techniques for xylem water pressure measurements, i.e. the Pressure Chamber (PC) and the Thermocouple Psychrometer (TP).
Capillary Rise Determination Using Simplified Image Analysis Method
Authors: Ramli Harris , Lee Zheng Xian , Azmi Mastura , Ahmad Fauziah
Published: October 2020

Capillary rise underestimation can reduce the long-term performance of civil engineering projects, especially those concerned with ground moisture, such as basements, roads, dams, and soil barrier liners. According to Peck et al. [1], the grain shape constant in empirical capillary rise estimation relationships varies between 10 and 50 mm2 and can be difficult to assume. Furthermore, the measurement of capillary rise in laboratory settings is also quite challenging because it occurs in the transition zone between saturated and unsaturated soils. This study focused on the application of the simplified image analysis method (SIAM) to capillary rise determination for the assessment of the grain shape constant as proposed by Peck et al. [1]. SIAM is a non-intrusive, non-destructive laboratory technique used to measure the temporal and spatial distribution of water saturation in whole domains. In this study, six one-dimensional tests were conducted using a 35 mm × 35 mm × 550 mm column to simulate capillary rise at fixed groundwater levels. The results show that values smaller than 25 mm2 should be used for coarser sand, whereas values greater than 25 mm2 should be used for finer sand. This study demonstrates that SIAM can be further utilized in studies of unsaturated soil, especially to assess soil saturation changes.
Developing a high capacity axis translation apparatus for gas shale testing
Authors: Kim Jinwoo , Ferrari Alessio , Ewy Russ , Laloui Lyesse
Published: October 2020

Gas shales are usually partially saturated due to hydrocarbon generation and often have a low in-situ degree of saturation less than 40 %. During stimulation, substantial fluid imbibition into the formation occurs due to high suction. Recent research on these shales showed that changes in saturation strongly affect the strength and elastic properties, as well as their hysteretic behavior. To date, most experimental methodologies were based on total suction control by the vapor equilibrium technique. We postulate that the more representative in-situ conditions can be reproduced by capillary pressure control using the axis translation technique. The main challenge, however, is that the capillary pressure range is limited and far from sufficient to bring gas shales to partially saturated conditions. This paper introduces our recent progress in developing a high capacity axis translation apparatus for gas shales testing. Four high air entry value (HAEV) filter candidates were tested and evaluated for their performances and suitability
Wetting-induced collapse behaviour of a natural and vegetated coarse pyroclastic soil
Authors: Capobianco Vittoria , Cascini Leonardo , Cuomo Sabatino , Foresta Vito
Published: October 2020

Unsaturated pyroclastic soils originated by Vesuvius volcano show a collapsible behaviour upon wetting with a significant reduction in volume and rearrangement of solid skeleton. The paper investigates the role played by vegetation on wetting-induced collapse behaviour (namely, collapsibility) of reconstituted unsaturated soil specimens through two series of wetting tests in a standard oedometer. The first series of tests was performed on bare soil specimens, as to resemble the site conditions. The second group of tests was conducted on the same soil previously vegetated for 20 weeks with perennial graminae species, which are frequently used as a nature-based solution for contrasting surface erosion along slopes in different geo-environmental contexts. First, an initial small vertical net stress was applied on partially saturated specimens having similar initial saturation degree, then collapse was induced by flooding the specimens with distilled water and final vertical displacements were measured. As main outcome, soil porosity is highly reduced by the growth of grass roots. Consequently, the potential wetting collapse in the rooted soils is inhibited by low values of porosity. For similar initial soil porosity, in both bare and vegetated specimens (after root growth), a further reduction of the volumetric collapse magnitude is observed.
Frost heave and thaw settlement of initially saturated-slurried and compacted-saturated materials
Authors: Tripathy Snehasis , Al-Hussaini Osama Mahdi , Cleall Peter John , Rees Stephen William , Wang Han-Lin
Published: October 2020

Soils and industrial waste in various geotechnical engineering applications are expected to experience freezing and thawing processes in various regions of the world where the winter and summer temperatures fluctuate between sub-zero and positive ambient temperatures. In this study laboratory tests were undertaken on three materials (Speswhite kaolin, Pegwell Bay soil and a cement kiln dust). A custom-made test set up was used to carry out the laboratory tests involving freezing and thawing processes. Initially saturated-slurried and compacted-saturated samples of the selected materials were subjected to one cycle of freezing and thawing to study the influence of material type and initial conditions on the one-dimensional frost heave and thaw settlement. The test results showed that the type of material and the initial conditions of the materials prior to the freezing process influenced the frost heave, frost heave rate, velocity of water flow, segregation potential, and thaw settlement. Compacted-saturated materials showed a tendency to exhibit a greater magnitude of frost heave as compared to their saturated-slurried counterparts.
Hydrophobisation of clays and nano silica for ground engineering
Authors: Saulick Yunesh , Lourenço Sergio
Published: October 2020

Altering the hydrophobicity of particles allows their use as functional construction materials in ground engineering (e.g. in barriers). This study examines the hydrophobisation of nano to micro particles by using two clays (kaolin and halloysite) and nano silica. To induce hydrophobicity, dimethyldichlorosilane (DMDCS) was used in concentrations varying from 0.25% to 20%. The sessile drop method was used to measure the contact angle (CA) of the particles. Kaolin was initially hydrophobic with a CA of 93 5◦ while the other two materials were hydrophilic. The addition of DMDCS to the materials increased CAs of all materials investigated. The maximum CAs recorded at 20% for the halloysite, kaolin and nano silica were respectively: 116 5◦, 143 3◦ and 144 6◦. The difference in CAs attained by the clays was attributed to their different structure. Scanning electron microscope-energy dispersive spectroscopy analysis showed increases in carbon content with only halloysite and nano silica after hydrophobisation. The results demonstrate that hydrophobising clays and nano silica can effectively improve their resistance to water infiltration.
A coupled hydro – mechanical approach for modelling the volume change behaviour of compacted bentonite
Authors: Bosch Jose A. , Ferrari Alessio , Laloui Lyesse
Published: October 2020

The volumetric response of compacted bentonites against environmental actions is a key aspect in most designs of nuclear waste repositories. The safety assessment of such repositories must account for robust and reliable models of stress–strain for bentonites. While many models for unsaturated low activity clays take advantage from the use of a generalized effective stress, its application to expansive soils has not found the same degree of success. One of the possible reasons is the complex water retention behaviour of these materials, which only recently has been successfully reproduced by numerical models. Here, by adopting an appropriate water retention model, a coupled hydro-mechanical approach to simulate the volume change behaviour of compacted bentonites is suggested. An explicit distinction between interlayer adsorbed water and capillary water is used to simulate the water retention behaviour. It is then shown that by using a precise water retention formulation, the volumetric behaviour can be interpreted within an effective stress–degree of saturation based framework. Some interesting results derived from the use of the effective stress include the shrinkage limit, the increase in stiffness of the elastic regime and the use of a single elastic coefficient for both wetting–swelling and reloading stress paths.
Swelling behavior of unsaturated claystone/ bentonite mixtures
Authors: Middelhoff Marvin , Cuisinier Olivier , Masrouri Farimah , Talandier Jean , Conil Nathalie
Published: October 2020

This laboratory experimental program investigated the impact of variations in the expansive mineral content, the grain size distribution of employed bentonite, the initial dry density and the selected hydration path on the water retention characteristics and swelling properties of processed Callovo-Oxfordian claystone and its mixtures with MX80 bentonite. The French reference concept for the disposal of nuclear waste in deep sedimentary rock formations envisages the reemployment of excavated material as backfill material, which is installed in situ by means of conventional compaction techniques. The investigations were of special interest as the major issues involving in situ compacted backfill materials were portrayed. Experiments showed that the impact of variations in the dry density on the water retention characteristics of all materials vanished as suctions exceeded 100 MPa. The negligible impact of variations in the initial dry density on the collapse behavior of claystone/ bentonite mixtures remained questionable.
BOREAL, Bio-reinforcement of embankments by biocalcification
Authors: Esnault Filet Annette , Gutjahr Ira , Garandet Aurélie , Viglino Amandine , Béguin Rémi , Monier Jean-Michel , Oxarango Laurent , Emeriault Fabrice , Castanier Perthuisot Sabine
Published: October 2020

Biocalcification is a recent in-situ soil consolidation solution. It is obtained by calcite precipitation under controlled biogeochemical conditions. The industrial process, for whose implementation Soletanche Bachy holds several patents, has been validated by several experiments, initially on laboratory scale and later in situ on industrial scale under static groundwater conditions. However, it was necessary to adjust the process to make it effective for use in embankments due to the potentially high ground water flows that may be present. This is one of the main aspects addressed by the BOREAL project (Bio-reinforcement of backfilled hydraulic structures), a 4-year research and development program. Injection tests performed on a 1:1 scale in a physical model allowed for the validation of the process’ feasibility in various soil types and configurations as well as under several hydraulic flow conditions. The prime objective of the process is to help mitigate erosion and liquefaction risks. The project’s results are applicable to saturated and non-saturated soils. The areas of application of the process and its objectives in terms of treatment are also discussed in the article.
Physical and geotechnical properties of a silty sand soil treated with calcium carbonate fixing bacteria
Authors: Garzón E. , Morales L. , Reca J. , Romero E. , Sánchez-Soto P.J.
Published: October 2020

The objective of the present study is to develop a biotechnological tool for a new application of silty sand soil as stabilized materials in linear works replacing chemical stabilizer (e.g. cement and lime) by natural cement, formed by precipitated calcium carbonate generated by microorganisms of the Sporosarcina family. For this purpose, it is conducted a chemical and mineralogical characterization and an examination of physical and geotechnical properties, being very important from the engineering standpoint. The results of different tests are presented here. The data show that the effects of bacteria are reducing the soil specific surface and increasing its plasticity. The reason for this result could be the addition of a plastic component to the natural soil, or the result of the more aggregated structure promoted during the treatment. The pore size distribution of the soil changes in an approximate range 3 - 30 µm, where the pore mode tends to disappear. The change in the pore density function is reflected in the mechanical behaviour of the treated soil, which presents typical features of a less dense soil with respect to the natural untreated one. The friction angle of the treated soil is slightly higher, and its compressibility is consistently lower than that of the natural soil. As the bacteria do not seem to produce any cementation effect on the soil skeleton, collapse upon wetting does not seem to be significantly affected by the treatment. On the contrary, comparison of collapse data shows that occurrence and amount of collapse are ruled by the as-compacted dry density. The tests performed seem to suggest that the microbiological technique may be effective to improve the mechanical characteristics of the compacted soil. For that, it is necessary to provide more energy in compacting the treated soil that it will be stabilized, so as to achieve a high initial dry density. From this viewpoint, it seems that higher compaction effort is even more effective than increasing the amount of bacteria introduced to stabilize the soil.
The effect of microbial calcite precipitation on the retention properties of unsaturated fine-grained soils: discussion of the governing factors
Authors: Saffari R. , Nikooee E. , Habibagahi G.
Published: October 2020

In recent years, biogeotechnology has been introduced as a novel and environmentally friendly technique for soil improvement. The need to address global warming and the adverse environmental effects of the chemical additives have led to the emergence and development of the techniques which use calcite producing microorganisms in order to improve soil mechanical properties. While the effects of microbial induced calcite precipitation (MICP) on the hydraulics and mechanics of saturated coarse-grained soils have been well examined and studied, there is not yet much information on the effects these microorganisms would have on the unsaturated soil mechanical behaviour. The first step, in this regard, is to understand the effect of the processes involved in the MICP on the soil retention properties. Soil water suction is a key factor controlling soil hydraulic and mechanical behaviour. In this study, the influence of MICP on the soil total suction in an unsaturated fine-grained soil sample has been explored using filter paper experiment. The results of this study revealed that by increasing the amount of bacterial solution, the soil saturation-total suction curves are significantly affected. The soil water retention changes are attributed to the change in double layer thickness as well as the precipitation of calcite crystals.
Amelioration of permeable soil with green liquor dregs for the construction of sealing layers for mine waste storage facilities
Authors: Kronsell Ida , Nigéus Susanne , Virolainen Anna , Jia Yu , Pabst Thomas , Marurice Christian
Published: October 2020

Mining of sulfidic ore generates acidic waste which often leads to the generation of acid rock drainage (ARD) having an adverse impact on aquatic flora and fauna. Engineered multilayer cover is one of the commonly used methods to prevent oxygen from being transported to mine waste. The sealing layer has a key function in the cover, thanks to its high water retention capacity and a low hydraulic conductivity, which enable the layer to remain near water saturation, effectively hindering oxygen diffusion. When adequate material is not available improvement of local soil material with a sealing agent is principally the only option to produce sealing layer material. Apart from bentonite clay, Green Liquor Dregs (GLD), a waste from the pulp and paper industry, have the ability to reduce the oxygen diffusion when mixed to granular soil, improving the water retention capacity of the blend. Experience from the development of Till/GLD-blends for the construction of sealing layers is compiled to address issue related to soil amelioration using waste with focus on material variation and quality control. The presentation focuses on the opportunities and challenges for the establishment of a circular system based on reutilization of a waste, herein GLD for improvement of soil’s geotechnical property.
Mechanical properties and microstructure of soils treated with a vinyl-based copolymer
Authors: Cuisinier Olivier , Sezer Alper , Graziano Sossio Fabio , Russo Giacomo
Published: October 2020

In soil stabilisation, the use of alternative products to lime or cement has been proposed. However, the effects of these additives, of various origins, on soil behaviour and stabilizing mechanisms are not well understood. Thus, the aim of this paper is to characterize the modification of the mechanical behaviour and microstructure of two soils after treatment with one of those product, a vinyl based copolymer. After treatment, both materials were compacted up to their maximum dry density. The mechanical behaviour of the materials as a function of the curing conditions, suction and water content was first determined. In a second step, the alteration of the microstructure by the treatment product was assessed. The results showed that the treatment permitted to significantly improve the strength of the tested soils. Moreover, the efficiency of the product increases when the soil is dried. However, the Young modulus is not significantly modified by the treatment. Microstructural reorganization after co-polymer addition has been detected by SEM technique for kaolin samples, whereas no modification have been observed for silt samples.
Estimation of the state of the cosmic ray flux based on neural networks
Authors: Mandrikova Bogdana , Dmitriev Alexei
Published: October 2020

An automated method is proposed for assessing the state of the cosmic ray flux on the base of neural networks. The method allows using the data of neutron monitors to determine the state of the cosmic ray flux in accordance with the a priori specified states of the neural network. The paper evaluates the method and presents the results of its application during periods of increased solar activity and magnetic storms. The possibility of realizing the method on-line is demonstrated.
Analysis of the data of IMF Bz and AE index for the period 1999-2018
Authors: Polozov Yuryi
Published: October 2020

Solar-terrestrial relations are a part of space weather and they make significant impact on technosphere functioning. Interplanetary Magnetic Field (IMF) parameters measured at Lagrange point L1 show the beginning of possible changes in geophysical fields. The paper analyzes statistically IMF Bz component (shows the level of impact on the Earth magnetic field) and AE index (used to estimate the energy contribution into magnetosphere and ionosphere). Using the apparatus of regression analysis and wavelet transform, time series were estimated. Regression models of IMF parameters and AE index were developed for the period 1999-2018.
Investigation of the process of strong acoustic signal propagation in a layered environment of ice-water-bottom
Authors: Korochentsev Vladimir , Tszyan’tszyun’ Chzhu , Chernenko Vasiliy , Lobova Tat’yana , Gubko Mikhail
Published: October 2020

A mathematical model was developed to calculate acoustic wave in a shallow sea under an ice layer for low frequency signals of 40-150 Hz. An experimental unit was developed by the authors on the basis of a low-frequency piston-type electrodynamic radiator which is capable of making experiments in layered environment. The experiments show satisfactory agreement with theoretical investigations. The peculiarities of wave propagation at water-ice boundary are under investigation. The developed models may be applied for new engineering systems for earthquake forecast when installing receiving systems in an ice layer.
Research of the process of radon accumulation in the accumulating chamber taking into account the nonlinearity of its entrance
Authors: Tverdyi Dmitriy , Parovik Roman , Makarov Evgeniy , Firstov Pavel
Published: October 2020

The paper presents a mathematical model of radon accumulation in a chamber, which takes into account the hereditary properties of the environment in which radon migrates, and also uses a nonlinear function that is responsible for the mechanisms of radon entering the chamber. The simulation of accumulation is performed in comparison with real data. It is shown that the model presented in this work gives a better agreement between the model and real curves of radon accumulation and can be used for a more accurate description of the processes occurring in the chamber.
Temporal regularities of changing magnetic field generation modes in the model of the αΩ-dynamo
Authors: Sheremetyeva Olga , Godomskaya Anna
Published: October 2020

In the dynamic model aΩ-dynamo the change in the intensity of the a-generator under the action of external forces is considered as a result of synchroniza-tion of higher modes of the velocity field and the magnetic field and is regulated by the function Z(t) with an exponential-power kernel J(t). Depending on the choice of the exponent and the scale factor of the kernel determine its temporal characteristics: delay time and waiting time. The question of changing the modes of magnetic field generation depending on the temporal characteristics of the function’s kernel is investigating. In the dynamic model aΩ-dynamo the change of the a-generator intensity under the action of external forces is considered as a result of synchronization of higher modes of the velocity field and the magnetic field and is regulated by the function Z(t) with an exponential-power kernel J(t). Depending on the choice of the exponent and the scale factor of the kernel J(t) determine its temporal characteristics: delay time and waiting time. The question of changing the modes of magnetic field generation depending on the temporal characteristics of the function’s kernel is investigating.
Two-mode dynamo as a oscillator with memory
Authors: Vodinchar Gleb
Published: October 2020

The hereditary two-mode model of the aw-dynamo proposed earlier by the author is studied from the point of view of the theory of oscillators. It is shown that this approach allows one to perform a qualitative analysis of the model’s behavior and predict possible dynamic regimes without numerical simulation. Examples of comparison of the results of qualitative analysis and modeling are given.
Applying general markup knowledge to analyze ionograms of various ionosondes
Authors: Mochalov Vladimir , Mochalova Anastasia
Published: October 2020

In order to improve the quality of recognition of ionograms, the use of general knowledge about the reference marking of ionograms at various points of installation of ionosondes of the same type is considered. On the basis of reference markings from two ionosondes, deep neural networks were trained to highlight reflection traces from different layers of the ionosphere. The resulting deep neural networks have been successfully applied to recognize ionograms of another type of ionosonde. The results of recognition are presented.
Features of the manifestation of lunar-solar tides in the electromagnetic parameters of the active fault zones of the Tien Shan
Authors: Bataleva Elena
Published: October 2020

The results of monitoring studies of the electromagnetic parameters of active fault structures on the territory of the Bishkek geodynamic proving ground are shown. The temporal variations of the electromagnetic field on several active faults of the Earth’s crust, characterized by different tectonic activity, are analyzed in comparison with the variations of lunar-solar tides. It was found that in the overwhelming majority of cases, the correlation dependences are most clearly manifested in changes in the real and imaginary parts of additional impedances than the main ones. Analysis of the cross-correlation function indicates that the reason for the change in the parameters of the electromagnetic field can be lunar-solar tides.
Responses to the preparation of strong Kamchatka earth-quakes in the lithosphere–atmosphere–ionosphere system, based on new data from integrated ground and iono-spheric monitoring
Authors: Bogdanov Vadim , Gavrilov Valerey , Pulinets Sergey , Ouzounov Dimitar
Published: October 2020

The experience of short-term forecasting of Kamchatka earthquakes based on complex well measurements at the Petropavlovsk-Kamchatsky geody-namic polygon (PGP) shows that, as a rule, the preparation of strong Kamchatka earthquakes is fairly reliable in the medium-term time scale (months or years be-fore the earthquake). However the determination of the stage beginning imme-diately preceding an earthquake (weeks or days before the main event) is a very difficult task. At present time, the solution of this problem is largely associated with the involvement in the preparation of forecast conclusions of data from continuous monitoring of the ionosphere, carried out by ground-based means of vertical radiosonding and measurements of total electronic content (TEC) using the global navigation satellite system GLONASS and GPS. This is due to the fact that significant changes in a number of ionospheric parameters occur mainly 1-5 days before the Kamchatka earthquakes. The results of the compar-ison of the data of daily monitoring of the ionosphere, including information on TEC, with the data integrated downhole measurements showed a rather high correlation of occurrence of anomalies in the ionosphere before strong earth-quakes with changes in the complex parameters in borehole measurements. As one example, the report presents the results of ionospheric and borehole monitoring obtained in the time neighborhood of the strong (MW= 7.5) the earth-quake that occurred on March 25, 2020 in the area of the Northern Kurils. The results show a high correlation between changes in the specific electrical resis-tivity of the Geospace in the area of the PGP with variations in the TEC and the formation of a number of other anomalies in the ionosphere a few days be-fore the earthquake. These results indicate that it is possible to determine fairly reliably the beginning of the final stage of preparation for a strong earthquake. Currently, methods based on atmospheric parameters monitoring are used quite successfully for predictive estimates of the epicenter and magnitude of an earth-quake: the method of chemical potential corrections for measurements at an altitude of ∼ 100 m, as well as data from measurements of outgoing long-wave infrared radiation (OLR) at the level of the upper edge of clouds (heights of 10 -15 km).
Lipoedema and Pain: What is the role of the psyche? – Results of a pilot study with 150 patients with Lipoedema
Authors: Erbacher Gabriele , Bertsch Tobias
Published: October 2020

Introduction The present exploratory study is the first so far to investigate the psychological stress in the period before the development of pain symptoms typical for lipoedema.

Methods 150 patients diagnosed with lipoedema syndrome were questioned in semi-structured interviews about psychological stress and were diagnosed with psychological disorders according to ICD-10 criteria. The development of the symptoms typical for lipoedema was recorded in a second interview. Both interviews were blended together in collaboration with the patients, this means Lipoedema-associated pain and psychological stress were related to time.

Result Exactly 80 % of the patients diagnosed with lipedema show a high level of psychological distress immediately before the onset of lipedema-associated symptoms! In this study, mental distress was defined as the presence of a manifest mental disorder (ICD 10 F diagnosis) such as Depression, eating disorder or post-traumatic stress disorder and/or serious psychological distress such as burnout syndrome or chronic stress.

Summary These results contradict a widespread statement that all psychological problems of patients with the diagnosis lipoedema syndrome are caused solely by lipoedema, that lipoedema even causes the patient’s mental disorder.

Moreover, depression and posttraumatic stress disorders are significantly related to the maximum pain intensity estimated by patients in everyday life. This demonstrates that it is imperative to rethink lipoedema therapy and to implement a psychosocial pillar in an overall therapy concept.
Multiple Sklerose in Deutschland: aktualisierte Auswertungen des MS-Registers der DMSG 2014–2018
Authors: Flachenecker Peter , Eichstädt Kerstin , Berger Klaus , Ellenberger David , Friede Tim , Haas Judith , Kleinschnitz Christoph , Pöhlau Dieter , Rienhoff Otto , Stahmann Alexander , Zettl Uwe K.
Published: October 2020

Einleitung Unter Federführung der Deutschen Multiple Sklerose Gesellschaft (DMSG), Bundesverband e. V. wurde 2001 ein bundesweites MS-Register initiiert, um epidemiologische Daten zur MS, deren Verlaufsformen und der Versorgungssituation in Deutschland zu erheben. Das Ziel der vorliegenden Auswertung war es, die Daten der letzten Auswertung von vor 10 Jahren zu aktualisieren.

Methodik Zum Stichtag 28. Februar 2018 nahmen 168 Zentren verschiedener Versorgungsbereiche (Universitätskliniken, Akutkliniken, Rehabilitationskliniken und neurologische Praxen) teil. Von 2014 bis 2016 wurde der Wechsel der Dokumentationsplattform zu einem internetbasierten elektronischen Datenerfassungssysstem (EDC) vorgenommen, das eine umfassende Datenerhebung und die Integration verschiedener Dokumentationssysteme erlaubt. Eine Reihe von Qualitätssicherungsmaßnahmen sichert eine valide und representative Datenerhebung. Um eine möglichst aktuelle Beschreibung der Versorgungssituation zu gewährleisten, wurde die Querschnittsanalyse auf Patientendaten der aktuellsten Visite aus den letzten 4 Jahren beschränkt.

Ergebnisse Daten von 18.030 MS-Betroffenen konnten ausgewertet werden. Das mittlere (± Standardabweichung) Alter betrug 46,3 ± 12,2 Jahre, 72 % der Patienten waren weiblich, im Mittel waren die Patienten 10,6 ± 8,7 Jahre erkrankt, der mediane EDSS lag bei 3,0. Die Mehrzahl der Patienten litt an einem schubförmigen Verlauf (74,2 %), 16,1 % hatten einen sekundär und 5,5 % einen primär progredienten Verlauf. Eine Immuntherapie wurde bei 75,2 % durchgeführt, am häufigsten mit Interferonen, gefolgt von Fingolimod, Glatirameracetat, Dimethylfumarat, Natalizumab und Teriflunomid. Symptomatische Therapiemaßnahmen erhielten zwischen 28,3 % (kognitive Störungen) und 86,0 % (Spastik) der Patienten, die an diesen Symptomen litten. Voll berufstätig waren nur noch 37,5 % der Betroffenen; 22,5 % waren vorzeitig berentet. Die berufliche Leistungsfähigkeit war negativ mit dem Alter und dem Behinderungsgrad assoziiert.

Diskussion Die vorliegende Auswertung des deutschen MS-Registers gibt einen aktuellen Überblick zur MS und deren Versorgungssituation in Deutschland. Die Ergebnisse sprechen für einen günstigeren Verlauf der MS im Lauf der letzten 10 Jahre. Während die Mehrzahl der Patienten mit immunmodulatorischen Substanzen therapiert wird, sind nach wie vor einige Symptome der MS wie Fatigue und kognitive Störungen unzureichend behandelt. Zwar hat die Beschäftigungsrate im Vergleich zu früheren Auswertungen zugenommen; dennoch erfordert der hohe Anteil der vorzeitig Berenteten effektive Maßnahmen, um die funktionellen Einschränkungen der Betroffenen zu verringern und ihnen die Teilhabe am gesellschaftlichen und beruflichen Leben möglichst lange zu ermöglichen.
Misteltherapie in der Onkologie – Update der aktuellen Forschungsergebnisse
Authors: Schad Friedemann
Published: October 2020

Mistelpräparate finden seit über 100 Jahren Anwendung in der Tumortherapie und sind im deutschsprachigen Raum nach wie vor die am häufigsten eingesetzten Arzneimittel in der integrativen Onkologie. Sie werden sowohl adjuvant als auch palliativ, meist in Kombination mit konventionellen Therapieverfahren angewandt und dienen in erster Linie zur Verminderung der durch diese Therapien bedingten Nebenwirkungen, der Verbesserung der Lebensqualität sowie der Reduktion tumorbedingter Symptome. In manchen Fällen kann auch eine direkte Tumorhemmung oder Tumorreduktion beobachtet werden. Einige Studien weisen auch auf eine Verlängerung des Gesamtüberlebens durch die Misteltherapie hin.

Zur Misteltherapie liegt eine Vielzahl an präklinischen und klinischen Studien vor. In dieser Übersicht wird die klinische Wirksamkeit anhand der aktuellen Studienlage und systematischen Reviews bzw. Metaanalysen besprochen. Außerdem werden Möglichkeiten einer Kombination mit gängigen Onkologika aufgezeigt.
Comparison of Clinical and Demographic Features of FMF with
Sacroiliitis Patients with FMF and Axial Spondyloarthritis Patients
Authors: Bayrak Esra Dilşat , Erten Sukran , Kucuksahin Orhan , Ersoy Osman
Published: October 2020

Objectives Familial Mediterranean fever (FMF) is the most common
autoinflammatory disease, characterised by recurrent fever and serositis
attacks lasting 1–3 days. Musculoskeletal involvement is the second
most common manifestation in FMF patients. Sacroiliitis is another
musculoskeletal involvement; as there is no spinal involvement, this is
called FMF with sacroiliitis. This study was designed to investigate the
clinical, demographic and genetic features of FMF in sacroiliitis patients
and to compare them with axial SpA and FMF patients.

Materials and Methods Forty-two FMF with sacroiliitis patients, 100
axial SpA patients and 100 FMF patients were recruited, and their
demographic characteristics were recorded. Evidence of sacroiliitis was
confirmed by sacroiliac joint MRI, and patients were examined for arthritis
and enthesitis. MEFV gene mutations, HLA B27 positivity and ESR and CRP
results were compared.

Results In the FMF with sacroiliitis group, the M694V mutation was
detected in 59.5% of patients. FMF with sacroiliitis patients were
largely (83.3%) negative for HLA B27. The frequency of enthesitis
was similar between FMF with sacroiliitis and axial SpA, and the frequency
of arthritis was higher in axial SpA patients. Inflammatory markers (ESR and
CRP) were statistically higher in FMF with sacroiliitis patients compared
with axial SpA and FMF patients.

Conclusion When all three groups were compared, the M694V mutation
was more common, HLA B27 was largely negative and inflammatory markers were
higher in the FMF with sacroiliitis group. FMF should be included in the
differential diagnosis of sacroiliitis for managing treatment correctly and
preventing complications.
An in silico study on the effect of the radionuclide half-life on PET/CT imaging with PSMA-targeting radioligands
Authors: Begum Nusrat Jihan , Glatting Gerhard , Eiber Matthias , Beer Ambros J. , Kletting Peter
Published: October 2020

Aim The aim of this work was to systematically investigate the influence of the radionuclide half-life and affinity of prostate-specific membrane antigen (PSMA)-targeting ligands on the activity concentration for PET/CT imaging.

Methods A whole-body physiologically-based pharmacokinetic (PBPK) model with individually estimated parameters of 13 patients with metastatic castration-resistant prostate cancer (mCRPC) was used to simulate the pharmacokinetics of PSMA-targeting radioligands. The simulations were performed with 68Ga (T1/2 = 1.13 h), 18F (T1/2 = 1.83 h), 64Cu (T1/2 = 12.7 h) and for different affinities (dissociation constants KD
of 1–0.01 nM) and a commonly used ligand amount of 3 nmol. The activity concentrations were calculated at 1, 2, 3, 4, 8, 12, and 16 h after injection.

Results The highest tumor uptake was achieved 1 h p. i. for 68Ga-PSMA. For 18F-PSMA, the highest tumor uptake was at 1 h p. i. and 2 h p.i for dissociation constants KD
 = 1 nM and KD
 = 0.1–0.01 nM, respectively. For 64Cu-PSMA, the highest tumor uptake was at 4 h p. i. for dissociation constant KD
 = 1 nM and at 4 h p. i. (9 patients) and 8 h p. i. (4 patients) for higher affinities. Compared to 68Ga-PSMA (1 h p. i.), the activity concentrations in the tumor for 18F-PSMA (2 h p. i.) increased maximum 1.3-fold with minor differences for all affinities. For 64Cu-PSMA (4 h p. i.), the improvements were in the range of 2.8 to 3.2-fold for all affinities.

Conclusions The simulations indicate that the highest tumor-to-background ratio can be achieved after 4 hours in PET/CT using high-affinity 64Cu-PSMA.
A Palladium-Free Sonogashira Coupling Protocol Employing an In Situ Prepared Copper/Chelating 1,2,3-Triazolylidene System
Authors: Sarkar Biprajit , Vougioukalakis Georgios C. , Tonis Efstathios , Stein Felix , Stamatopoulos Ioannis K. , Stubbe Jessica , Zarkadoulas Athanasios
Published: October 2020

A new, palladium-free Sonogashira coupling reaction protocol using a catalytic system that comprises a simple, cheap, widely available copper salt and a chelating 1,2,3-triazolylidene ligand precursor is reported. This protocol provides the desired coupling products in moderate to very good yields.