bluuebunny/crossref_metadata_2025 huggingface dataset:
Discovery of the interstellar cyanoacetylene radical cation HC3N+
Authors: Cabezas C. , Agúndez M. , Endo Y. , Tercero B. , Marcelino N. , de Vicente P. , Cernicharo J.
Published: July 2024

We report the first identification in space of HC3N+, the simplest member of the family of cyanopolyyne cations. Three rotational transitions with half-integer quantum numbers from J = 7/2 to 11/2 have been observed with the Yebes 40 m radio telescope and assigned to HC3N+, which has an inverted 2Π ground electronic state. The three rotational transitions exhibit several hyperfine components due to the magnetic and nuclear quadrupole coupling effects of the H and N nuclei. We confidently assign the characteristic rotational spectrum pattern to HC3N+ based on the good agreement between the astronomical and theoretical spectroscopic parameters. We derived a column density of (6.0 ± 0.6)×1010 cm−2 and a rotational temperature of 4.5 ± 1 K. The abundance ratio between HC3N and HC3N+ is 3200 ± 320. As found for the larger members of the family of cyanopolyyne cations (HC5N+ and HC7N+), HC3N+ is mainly formed through the reactions of H2 and the cation C3N+ and by the reactions of H+ with HC3N. In the same manner than other cyanopolyyne cations, HC3N+ is mostly destroyed through a reaction with H2 and a dissociative recombination with electrons.
Messinian canyons morphology of the Rhône and Ardèche rivers (south-east France): new insights from seismic profiles
Authors: Do Couto Damien , Cushing Edward Marc , Mocochain Ludovic , Rubino Jean-Loup , Miquelis Florian , Hanot Franck , Froment Bérénice , Gélis Céline , Camus Hubert , Bagayoko Nanaba , Bellier Olivier
Published: July 2024

Twelve available two-way time high-resolution seismic reflection profiles located in the central part of the middle Rhône valley are interpreted. In addition, one of the profiles was reprocessed to determine the P-wave velocities of the main geological units and to convert this profile into a depth cross section. The Lower and Upper Cretaceous units are clearly identifiable on all the profiles, along with the Messinian Erosion Surface (MES) carved out during the Messinian Salinity Crisis (MSC) by the paleo-Rhône and its western tributaries, the Ardèche and Cèze paleo-canyons. The Plio-Quaternary fill of these paleo-canyons shows at least 4 main units with an overall transgression. The combination of geological data from geological maps, geological field surveys and borehole data made it possible to model the MES in 3D at the scale of the region, and to produce depth/elevation model. From a geological point of view, the interpretation of the seismic profiles enabled us to reconstruct the stages in the sub-aquatic filling of the Messinian-Pliocene aggradation of the paleo-river. Several Mass Transport Deposits (MTDs) were identified both during the drop and during the rise in the Mediterranean Sea level. From a geomorphological point of view, this study provides new insights in the route and longitudinal profile of paleo-rivers and, in particular, it deepens the profile of the Paleo-Rhône at the latitude of the Tricastin region (up to −700 m b.s.l.) and significantly modifies the course and depth of the Ardèche proposed in previous studies. The N-Ardèche river, known to develop a karstic system during the MSC, is connected to a deep canyon, most likely through a karstic pocket valley, as suggested by the very steep longitudinal profile of the MES. Finally, from a structural point of view, our interpretation of the seismic profiles shows a broad ENE-trending anticline structure associated with a normal fault which apparently did not affect the Mio-Pliocene fill. In the southern part of the area, near the Uchaux anticline, the imaged structures suggest the presence of a recent (syn- to post-Pliocene) fault propagation fold. In addition to all the new information on the geology, morphology and methods of excavation and filling of the Messinian paleo-canyon, the proposed topographic model of the paleo-canyon is crucial for modelling seismic movement in the context of a basin with a complex geometry and, in particular, for the numerical assessment of site effects in a context of low seismicity.
A simplified cyclic shear test for pore water pressure build-up of different soils
Authors: Baćić Božana , Herle Ivo
Published: July 2024

Pore water pressure (PWP) build-up essentially takes place in loose, water saturated, coarse-grained soils causing the reduction of effective stresses and soil stiffness (soil liquefaction). Considering the same internal structure (soil fabric), stress level, loading amplitude etc. the response of different soils to external disturbance is different. Therefore, the increase of PWP or tendency to soil liquefaction is dependent on the granulometric properties of soils. This paper reveals a simple cyclic shear test that enables the comparison of the sensitivity of PWP build-up to density changes for different sands. The presented test allows a fast installation of a soil specimen and a subsequent constant volume cyclic shearing within a short time period (ca. 30 minutes). The results successfully confirm the repeatability of the method as well as the dependence of the PWP build-up on the initial relative density and saturation degree. It is also shown that the soil fabric has an essential influence on the build-up of PWP. The method aims to allocate an index value to every tested sand and thus to quantify a sensitivity of different sands to density changes with respect to liquefaction.
Small-strain stiffness of liquefiable sands: A comparison between bender elements and resonant-column tests
Authors: Molina-Gomez Fausto , Viana da Fonseca Antonio , Ferreira Cristiana , Camacho-Tauta Javier
Published: July 2024

Soil stiffness can be estimated by geophysical and dynamic testing methods. In the laboratory, the most common methods to measure the small-strain stiffness are the bender elements (BE) and resonant-column (RC) tests. This paper focuses on the comparison between the results of the small-strain stiffness of sands by BE and RC tests. For this purpose, an experimental program involving three liquefiable sandy soils (i.e., NB, TP-Lisbon and Toyoura sands) was carried out. Such program covered the measurement of the small-strain stiffness of these soils by BE in triaxial and RC apparatuses for different mean effective stress conditions. All tests were carried out on saturated soil specimens, which were remoulded using the air pluviation method for various relative densities. The experimental results were interpreted in terms of shear-wave velocity (Vs) and maximum shear modulus (Gmax) to derive the stress-dependency laws of these parameters. The experimental results revealed differences between Vs obtained from BE and RC tests, evidencing a clear effect of relative density on the shear-wave propagation. However, such a variation may be significantly reduced when a normalisation of Gmax in terms of a void ratio function F(e) is applied. As a result, this study demonstrated and validated the importance of accounting for the soil state conditions, for adequate compatibility of BE and RC tests in the estimate of the small-strain stiffness of liquefiable sands.
Application and comparison of multistage triaxial compression test procedures on reconstituted Ankara clay
Authors: Vakilinezhad Amirahmad , Toker Nabi Kartal
Published: July 2024

The ability to conduct conventional triaxial compression tests on multiple identical specimens is restricted by available sample quantity, sample homogeneity, as well as testing duration. Multistage triaxial testing is an alternative method to tackle these issues by using a single specimen sheared under different confining stresses to attain the strength parameters. Although there are widely accepted procedures to decide when to stop each shearing stage and proceed to the next stress level, the applicability of these procedures on different soil types is still a question. This study examines the applicability of combinations of two multistage triaxial testing procedures (Rational Procedure and Minimum Slope) under two different deviator stress conditions (Sustained or Cyclic) during confining stress increase. The outcome is compared to conventional triaxial test results for undrained and drained shearing of reconstituted specimens of high-plasticity Ankara Clay. Out of the four options, the rational procedure with cyclic deviator loading and minimum slope with cyclic deviatoric loading conditions, are found to give the most accurate strength parameters in reference to single-stage test results. The maximum number of the shearing-reconsolidation sequences applicable before strength loss is also investigated for each multistage triaxial testing procedure.
High-precision and high-accuracy stereophotogrammetric image analysis for small to large strain deformation measurement in triaxial apparatus
Authors: Nishimura Satoshi
Published: July 2024

A deformation measurement system for laboratory soil testing based on stereophotogrammetric image analysis was developed with a purpose of characterising soil behaviour continuously from small to large strains. The system is applicable to triaxial tests with pressure chamber and confining fluid by correcting the refraction-induced distortion of images by ray tracing. In comparison to similar existing studies, the present study put priority in precision and accuracy in relative displacement tracking, which is the key feature in resolving small strain in soil specimen and characterising its stiffness. The displacement tracking is performed with a hybrid algorithm combining Particle Tracking Velocimetry (PTV) for primary target matching and subpixel Digital Image Correlation (DIC) for more precise image matching. The deformation of clay samples with and without end lubrication was compared by visualising the deformation at different levels of strain. This paper is basically a summary of Nishimura (2022). Another example of application in laboratory testing involving fine particle suffusion is also shown. Some notes on implementation of the technique for good practice and on future development are additionally described.
Transient phase in shear zone formation in sands
Authors: Rathore Sudhanshu , Hegde Abhijit , Murthy Tejas Gorur
Published: July 2024

An experimental study has been made to study the emergence of narrow shear zones (“shear bands”), in uniformly graded quartzitic sand under dry conditions using the model setup of orthogonal cutting. A fixed region of interest around the stationary tool is imaged using a high-resolution and high-speed camera and further analyzed using Particle Image Velocimetry (PIV) algorithm to obtain the flow (velocity) fields. The velocity field maps of the near tool tip region demonstrate sharp change in the motion of sand particles along with the formation of a “dead zone” – a region of material stagnation or no flow. This extent of the dead zone was found to fluctuate in time for a given cutting speed, and no significant effect of the cutting speed (or strain rate) is observed in the propagation of dead zone size. The dynamic repose angle of the evolving sand pile in front of the tool increases initially and then attains a steady value of around 40°. The regions of intense straining in the sands were revealed in the effective strain rate fields. The shear localization was seen to emerge from the tooltip and propagate toward the free surface. The inclination angle of these bands evolves periodically with time and showed a decreasing trend due to an increase in the surcharge. The oscillatory force signatures suggested that every undisturbed ensemble of sands, on reaching the tool vicinity, undergoes material softening (dilation) followed by hardening(compaction), which is also reflected in the periodic formation and destruction of shear bands.
Investigation of coated hydrophobic granular materials by means of computed tomography and environmental scanning electron microscopy
Authors: Toffoli Clara Magalhães , Milatz Marius , Grabe Jürgen
Published: July 2024

Hydrophobic materials in geotechnical engineering and soil science can have natural or artificial origin. They can be applied, e. g., to waterproof structures in the industry. In this contribution, hydrophobic granular material was manufactured through a cold plasma polymer coating procedure. The monomer used was C4F8 (octafluorocyclobutane) and the material to be coated was Hamburg sand, a coarse grained sand. In this context, computed microtomography and environmental scanning electron microscopy were used to investigate the materials in their unsaturated state. The tools are applied to visualize unsaturated phenomena on the microscale. The hydrophobic and untreated materials were imaged by both techniques at different saturation degrees in order to understand the influence of the coating on the sample’s hydraulic behaviour. The chosen environmental scanning electron microscope is able to provide relative humidity in the sample chamber, and so water drops were condensed on the grain surface, allowing to also observe the initial contact of water and the hydrophobic coating. It was observed how the capillary menisci, their geometry and contact properties evolve at different degrees of saturation. The measurements obtained and respective analyses state qualitatively the influence of the hydrophobic coatings on the pore water dynamics at different saturation degrees, which dictates the material’s hydraulic behaviour. Contact angles were also analysed were it was physically possible.
Simplified modelling of full-strain-range non-linearity of cyclically loaded undrained clays
Authors: Huang Maosong , Cui He , Shi Zhenhao , Yu Jian
Published: July 2024

Constitutive modelling of cyclically loaded undrained clay is of significant importance for various branches of geotechnical engineering exemplified by offshore wind turbine (OWT) foundation design and prevention and mitigation of earthquake hazards. Fine-grained soils can display non-linear stress-strain relations from small (10-5) to relatively large (10-1) strain levels. This full-strain-range non-linearity can remarkably affect the cyclic response. Effective stress-based constitutive models have achieved great success in modelling clayey soils, whereas they can be overly complex for practicing engineers, in particular, when considering non-monotonic loading and full-strain-range non-linearity. This paper explores the possibility of modelling, in simplified manner, the full-strain-range nonlinearity of cyclically loaded undrained clay, which can directly utilize outcomes of in situ site exploration and routine laboratory tests. For this purpose, we idealize soils under undrained conditions as single-phase materials governed by total stress. Considering that most current total stress-based models are proposed for metals and may be limited to capture the non-linear stress-strain relations of soil, a novel generalized non-linear (GNL) hardening law is proposed that can describe versatile stress-strain relations of undrained clays. Bounding surface and a mapping rule considering update of projection centre are introduced to reflect the influences of maximum past stress history and recent stress history, respectively, on the stress-strain nonlinearity. The simplified constitutive model is first validated at the element level by simulating monotonic and cyclic loading laboratory tests on undrained clays. Later, the proposed soil model is applied to the finite element analyses of OWT pile foundation subjected to cyclic lateral loading.
Performance evaluation of the Generalized Bounding Surface Model in the simulation of Cajicá clay subjected to monotonic loading
Authors: González-Olaya Ricardo , Camacho-Tauta Javier , Molina-Gómez Fausto
Published: July 2024

Different constitutive models, based on principles of mechanics and experimental evidence, have been developed over several decades to represent and predict the stress-strain behavior of soils subjected to various loading conditions. The Generalized Bounding Surface Model (GBSM) is one of them and is defined as a fully three-dimensional elastoplastic constitutive model for saturated cohesive soils that employ the bounding surface plasticity in conjunction with a nonassociative flow rule and a soil microfabric-inspired rotational hardening rule. The GBSM has been successfully validated on numerous laboratory reconstituted soils, but not on natural or undisturbed soil samples. Hence, in this paper the predictive capabilities of the GBSM are evaluated in the simulation of the monotonic behavior of an undisturbed cohesive soil called “Cajicá clay” from the high plain of Bogotá in Colombia. In the first instance, an isotropic consolidation test and a set of axisymmetric triaxial compression and extension tests are conducted using an automated triaxial equipment, to experimentally describe the response of the undisturbed soil. From experimental data, the parameters associated with the GBSM model are calibrated to finally evaluate its capabilities in the simulation of a cohesive natural soil. A comparison between experimental data and numerical simulations is presented to show both performance and advantages of the GBSM model.
Mesoscale FEM approach on cemented sands: Generating and testing the digital twin
Authors: Komodromos Michail , Stamati Olga , Grabe Jürgen
Published: July 2024

The mechanics of Cemented Granular Material (CGM) have been studied by means of geotechnical experimental testing, whose output consists the basis of mathematical models which approach the material response in various loading states. The information derived from standard experimental response curves is the basis of understanding and handling the material. Still, it is intuitive to analyse the CGM down to the mesoscale and dray conclusions over the interaction of the constituent material phases. Diverging from the practice of equivalent continuum, the alternative description of a three phase composite of sand particles, cement binder and void pores has been realised in this study. In order to implement the specific morphology of this multiphase, geomaterial, X-ray Computed Tomography is used to capture the internal structure and quantify it into a three dimensional greyvalue map (or a three dimensional image). The distinction of the material phases is made possible by the application of a developed filter, which corrects the artefacts caused by beam hardening phenomena and allows for the generation of a phase segmented equivalent image. An image adapted meshing algorithm has been utilized to transform the labelled image into a tetrahedral mesh, grouped into sets that correspond to the different materials. The tetrahedral domain was assigned boundary conditions and was numerically tested under uniaxial compression using the finite element method. The kinematics of the simulation proved that the mesoscale approach, which carries internal structure information of the granular fabric and the cement paste distribution, provides a output which captures the kinematics of the granular skeleton.
Dynamic shear modulus and damping ratio of recycled concrete aggregate—recycled tire waste mixture using resonant column apparatus
Authors: Gabrys Katarzyna , Sas Wojciech
Published: July 2024

The accumulation of waste tires is a global problem related to natural resources and the environment. The storage or burning of tires causes toxic chemicals to seep into the surrounding environment, which poses a serious ecological threat. Many previous studies have shown that waste tires can be used in geotechnical engineering. It was found that rubber reinforcement can increase the plasticity of sandy soil and improve its shear strength. It can control pore water pressure accumulation and improve dynamic properties. For cohesive soils, rubber additives can reduce dry density and improve compressive strength and soil stability. When mixed with soil with optimum content, waste tires can reduce various adverse effects of waste tire accumulation on the environment. The application of rubber has also a good impact on environmental protection and the promotion of “green design”. This paper presents the dynamic properties (shear modulus and damping ratio) of the RCARTW mixture for small, medium, and large ranges of shear strain levels (from about 1.510-4% to 1.310-2%). All specimens are constructed using different percentages of granulated tire rubber and concrete aggregate from curb crushing. A series of laboratory tests, resonant, and damping, are performed in the resonant column apparatus. The maximum shear modulus and minimum damping ratio are presented with the percentage of granulated rubber. The normalization is also applied to the Gmodulus and Dratio data set. Furthermore, a comparison is made between the results obtained for the tested geocomposites and a mixture of pure RCA.
Small-strain shear stiffness of sand-gravel mixtures
Authors: Pokhrel Abilash , Chiaro Gabriele
Published: July 2024

Small-strain shear stiffness (G0) is a key parameter for seismic ground response analysis and performance evaluation of various earth structures and foundations. To account for its pressure and density dependency, G0 has been conveniently correlated to mean effective stress (σm′) and void ratio (e). Such an approach is suitable for conventional uniform materials. However as found in this study, it is not always applicable to estimate the G0 of sand-gravel mixtures (SGMs), because it essentially fails to account for the combined effects of density and gravel content (GC). In this study, aimed at addressing this issue and developing a theoretical framework and empirical correlations suitable for estimating the G0 of SGMs, a series of bender element laboratory tests were carried out on selected SGMs. Specifically, SGMs were obtained by mixing two clean sands – namely New Brighton Sand (mean diameter, D50 = 0.2 mm) and Dalton River Washed Sand (D50 = 0.75 mm) – and rounded pea gravel (D50 = 5.5 mm). Shear wave velocity of specimens having GC = 0, 10, 25, 40 and 60% and prepared at a relative density (Dr) of 20, 30, 45 and 60% was measured at σm′ = 50, 100, 150 and 200 kPa. The laboratory results indicated that G0 of SGMs increases with increasing both the Dr and σm′, whereas the effect of GC would be marginal to significant depending on the limiting and threshold sand contents. To correlate G0 simultaneously with both GC and Dr, the equivalent void ratio (ef(eq)) was adopted. It is shown that the use of ef(eq) makes it possible to uniquely describe the G0 of SGMs for any combination of GC and Dr over the full range of σm′ level applied in this study.
Stiffness moduli in triaxial tests on a loess-sand mixture
Authors: Tankiewicz Matylda , Kowalska Magdalena
Published: July 2024

Stiffness is one of the most important characteristics of geomaterials, and at the same time one of the most difficult to evaluate. It can be described by means of various stress-strain moduli, whose values strongly depend on the strain range and on the method of determination. The aim of the article is to evaluate and compare selected stiffness parameters (Young’s modulus E and shear modulus G) of an anthropogenic soil on the basis of triaxial tests. The experiments were carried out on samples consisting of loess mixed with sand. Loess is a collapsible aeolian sediment with a high calcium carbonate content and so it is a very challenging material for geotechnical applications. The addition of sand improves its properties and increases its suitability for earthworks. The specimens were compacted with normal Proctor energy at the optimal water content, which ensured repeatability of the results. Standard triaxial tests (drained and undrained) were carried out at the effective confining stresses in the range of 50 – 350 kPa. The specimens’ deformation was measured by means of external and local displacement transducers. Additionally, bender elements were used to assess the initial soil stiffness. The applied research methods allowed determination of the deformation characteristics in the range from very small to large strains. The stiffness moduli were assessed using different definitions and methods. It was confirmed that the stiffness of loess is improved by its proper compaction and addition of sand, when compared to the results available in literature for natural loesses.
Undrained shear strength of soils with fine fraction content derived from compression and extension loading triaxial tests
Authors: Tymiński Wojciech , Kiełczewski Tomasz , Paweł Stefanek
Published: July 2024

In the stability analysis of dams or deep excavations a calculation scheme of soil response is assumed that considers the rotation of main stresses. In the case of tailings dams constructed of granular material with fine fraction content (FC <0.075 mm), an additional factor is to be considered i.e. liquefaction phenomenon. Soil response to undrained shearing in compression loading (increase of vertical stress) and extension loading (increase of horizontal stress) differs significantly, giving various strength values. The paper presents the results of triaxial tests carried out on soils with fine fraction content. The tests were performed under compression loading and extension loading conditions. The test results’analysis was performed, considering grain size impact and main stresses application method at the shearing stage.
Influence of initial compaction and confining pressure on the hydraulic conductivity of compacted iron ore tailings
Authors: dos Santos Roberto Aguiar , Delgado Bruno Guimarães , Rissoli Ana Luisa Cezar , Silva João Paulo de Sousa , Dal Toé Casagrande Michéle
Published: July 2024

The hydraulic conductivity of iron tailings is an important factor affecting the stability of tailings storage facilities. Stacking compacted filtered ore tailings is a promising alternative for safer tailings disposal. These tailings storage facilities’ internal drainage systems must be designed appropriately to avoid excessive seepage pressure, saturation, and slope failure. In this context, the factors that affect hydraulic conductivity must be adequately evaluated. Therefore, the hydraulic conductivity behavior of compacted iron ore tailings still needs to be investigated. In addition, the effect of high confining pressure on hydraulic conductivity needs to be evaluated. This study investigates the impact of the initial compaction and the confining pressure on hydraulic conductivity. For this, the flexible wall permeameter tests were carried out on filtered ore tailings compacted in three degrees of compaction: 77, 94, and 101% of optimum dry density as determined by the standard Proctor method. These specimens were saturated and then consolidated with different confining pressure. It is possible to affirm that the increased confining pressure decreases the hydraulic conductivity. The hydraulic conductivity decreases by less than one order of magnitude, regardless of the initial compaction. Moreover, the data suggest that hydraulic conductivity’s decay rate depends on initial compaction—the hydraulic conductivity of the loose specimen decays at a greater rate than that of the dense specimens. However, the reductions of the void ratio under the confining pressure of 1600 kPa and 2200 kPa were not enough to decrease the hydraulic conductivity. Thus, under high-stress confining, the hydraulic conductivity becomes practically constant.
Contractancy and shear behavior of extremely loose structure soils with particle breakage in saturated and unsaturated conditions
Authors: Sato Itsuki , Kuwano Reiko , Otsubo Masahide
Published: July 2024

Pumices with high pore voids of volcanic origin are distributed throughout Japan and are the causal layer of slope failures. In many cases of surface failures, it is difficult to assume that the resulting layers are fully saturated. The high waterholding capacity of the pumice suggests that they were deposited in an unsaturated state with a high degree of saturation. In this study, saturated triaxial compression tests and fully undrained unsaturated triaxial compression tests were conducted on artificially produced pumice and natural pumice while measuring the amount of crushing. This is to clarify the relationship between the crushing and mechanical properties of pumice with porous particles, which are often the cause of such disasters, and their behaviour under unsaturated conditions. The results showed that the pumice stones have an ultra-high pore structure. Moreover, pumice with porous particles reached a steady state under both saturated and highly saturated unsaturated conditions, and the amount of crushing increased under highly saturated unsaturated conditions.
Quality of reconstituted tailings samples based on their mechanical response
Authors: Oliveira João , Coelho Paulo , Araújo Santos Luís
Published: July 2024

With a growing global population and greater environmental awareness modern societies inevitably need more mineral resources. Thus, an increase in mining activity is expected through the reactivation of old mines and/or the licensing of new explorations. Increased mining operations will lead to the production of higher volumes of tailings that often endanger people and the environment.

To suitably assess the behaviour of tailings, it will be necessary to carry out a complete and exhaustive laboratory characterisation in order to determine the necessary parameters for the correct sizing of the tailings disposal structures. In this sense, for a successful laboratory work, it is necessary to obtain good quality intact or remoulded samples for testing and comparison. However, good quality intact samples of tailings are rarely available. Therefore, reconstituted samples assume an important role. Currently the most commonly used reconstitution methods for mine tailings are the moist tamping and slurry methods.

This paper aims to discuss the potential of the most commonly used sample reconstitution methods in mine tailings. Some mechanical characterisation studies of tailings are also presented, namely when subjected to monotonic and cyclic stresses, with the aid of triaxial and oedometer equipment. Complementary tests with unusual equipment, such as Hollow Cylinder Apparatus (HCA) and bender elements, are also presented. Finally, and in view of the research carried out, the main limitations in laboratory tests carried out on these materials are identified.
Monotonic and cyclic behaviour of sand-silt mixtures through the equivalent state parameter
Authors: Papadopoulou Anthi , Tika Theodora
Published: July 2024

This paper presents the results of a laboratory investigation into the effect of non-plastic fines on the monotonic and cyclic behaviour of sand-silt mixtures. For this purpose, drained and undrained triaxial monotonic and undrained stresscontrolled cyclic triaxial tests were performed on clean sand and its mixtures with non-plastic silt. The Critical State theory known as a characteristic state of soil behaviour and the equivalent state concept were used to the interpretation of the laboratory tests results. By estimating parameter b, which recognizes that different percentages of fines contribute differently to the strength of the sand and consequently the equivalent intergranular void ratio, (eg)eq, a single Critical State Line, CSL, is determined in the (eg)eq-log(p΄) plane, and a single liquefaction resistance curve at the CRR15-(eg)eq, independently of fines content, fc, based on the monotonic and cyclic tests results, respectively. It is shown that parameter b depends on the fines content, fc, and on the loading type of the laboratory test conducted, while (eg)eq proves to be a suitable parameter for the estimation of the monotonic behavior and undrained critical state strength as well as the liquefaction resistance of granular mixtures up to the threshold fines content value, fcth, independently of their fines content. The effectiveness of state parameter, ψ, and equivalent state parameter, (ψg)eq, in the estimation of the undrained critical state strength and liquefaction resistance of sand-silt mixtures is confirmed.
Frozen soil properties modification in the context of climate change
Authors: Jean Daniel Torche Jérémy , Howald Erika Prina
Published: July 2024

One of the expected effects of global warming is the gradual melting of permanently frozen ground, known as permafrost. The melting of permafrost will significantly impact soil material properties and (pore) fluid flow, potentially causing instability of infrastructures and triggering natural hazards such as landslides, rock falls, or debris flows. The overall objective of this research is to experimentally quantify the effect of thawing on the geomechanical strength of a reconstituted soil. More specifically, it is intended to qualify the initial frozen state and compare it to the state after thawing. The proposed experimental study was carried out in three steps. Firstly, soil samples were identified by the usual parameters such as water content, bulk density, solid particle density, triaxial test etc. Permafrost temperatures recorded by PERMOS and PermaFrance in the Alps (Swiss and French) are of the order of -3 to -4.5°C at a depth of -10m. This is why, for the second step, the shear tests were carried out at a slightly lower temperature than that recorded in situ. Artificial samples were sheared at a temperature of -5°C in our temperature controlled triaxial press in order to determine the soil’s strength parameters (cohesion and internal angle of friction). Thirdly, same tests were carried out at a temperature of +5°C in order to thaw the soil completely before the shearing. In total, three tests for each temperature were compared and discussed. The expected results aim at a better understanding and quantification of soil strength reduction after the thawing phase. As many infrastructures are now built on permafrost, such as roads, ski infrastructures, power lines or alpine chalets, they will be affected by this phenomenon in the near future. A better understanding of (geo)mechanical consequences might facilitate risk analysis, evaluation and mitigation.
Root-induced changes in the hydraulic properties of a fine slope cover
Authors: Tagarelli Vito , Stasi Nico , Cotecchia Federica , Cafaro Francesco
Published: July 2024

Recently, the soil-vegetation-atmosphere (SVA) interaction is becoming a topic of intense scientific research within the geotechnical community, because it was recognized to potentially induce significant pore pressure variations in slopes, at both shallow and larger depths, being then responsible for weather-induced landsliding.

The processes within such interaction are of different nature, and result in a chemo-thermo-hydro-mechanical transient boundary condition at the ground level, causing exchanges of liquid, gas and energy within the soil cover layer (from ground level to 3-4 metres depths). Hence, both the soil cover material and its thermo-hydro-mechanical constitutive properties, as well as the vegetation properties, become of key relevance within such processes.

In this study, with reference to a full scale in-situ test where deep-rooted crop spices were seeded and farmed, the hydraulic properties of rooted clayey soil were investigated in the laboratory as well as in-situ in terms of both saturated permeability and retention properties. As for the saturated permeability, both laboratory and in-situ tests were conducted, the latter being also back-analysed. The retention states of the material were investigated by means of the filter paper technique in the laboratory and were of use for the numerical back-analyses of the Guelph-induced wetting process in the soil cover. The measurements show that roots within the vegetated zone determine both an increase of the permeability and a reduction of the retention properties of the composite material if compared to the soil in bare conditions.
Multivariate probabilistic assessment of a regional database in Copenhagen
Authors: Panagiotis Efthymios , Rocchi Irene , Zania Varvara
Published: July 2024

Extensive research has been carried out to establish empirical equations between two geotechnical properties and in spite of the increase in correlation studies, a construction of a multivariate distribution function of more than two parameters is still rare. The objective of this study is to investigate the possibility of constructing two multivariate distribution functions, each consisting of 5 geotechnical parameters based on a) triaxial and soil classification tests and b) oedometer and soil classification tests in stiff over-consolidated clay till from Copenhagen. For this purpose, laboratory measurements from twenty-six sites in Copenhagen are utilized and two multivariate databases are constructed. The correlations among the ratio of deviatoric and mean effective stresses (q/p´), over-consolidation ratio (OCR), secant modulus at reference stress 100 kPa (E50ref), initial void ratio (eo) and liquid limit (LL) are investigated in multivariate model A, while multivariate model B demonstrates the correlations among oedometer modulus at 100 kPa reference stress (Eoed(ur)ref), over-consolidation ratio (OCR), permeability change index (Ck), initial void ratio (eo) and liquid limit (LL). The Nataf transformation model is used for the construction of the multivariate distributions, which are then used to simulate the correlations between geotechnical properties by generating artificial samples. Finally, the artificial samples are compared with the original database for an initial validation of the model. The constructed multivariate models obtained as a result of this study can act as prior for Bayesian updating in multivariate distribution functions when additional geotechnical tests are carried out.
Constrained modulus of fine-grained soils from in situ-based correlations and comparison with laboratory tests
Authors: Dhimitri Luisa , Powell John J.M.
Published: July 2024

The Constrained Modulus of soil is an important parameter to quantify compressibility of soils and calculate consolidation settlements, especially for clays. It is often expressed in terms of 1D constrained modulus, M or its inverse coefficient of volume change, mv. One method that has been suggested to assess M is from Cone Penetration Testing (CPTU) measurements through various correlations. Although, this is sometimes difficult, because of uncertainties regarding the appropriate stress, σ’v0, which are highly affected by the groundwater and bulk density γ, of soils. The usual method to measure M (or mv) is from oedometer tests in laboratory. Correlating in situ tests with laboratory tests results is crucial to increase the quality of soils strengths and stiffness information for design. However, most of the times it is a challenging process, which involves many uncertainties from different soils’ tests. This paper will look at comparison of CPTU derived M to oedometer tests taking into consideration various types of soils mostly from well-documented testbed sites where high quality in situ (CPTU for all sites and SDMT where available) and oedometer tests are carried out. The importance of CPTU measurements and site-specific correlations with laboratory tests to establish unique soil type coefficients for use in equations to derive CPTU-based M will be highlighted.
Evaluation of wet front under foundation at “El Chocón dam” using electrical tomography
Authors: Rinaldi Victor , Restelli Fabian , Rinaldi Jose Ignacio
Published: July 2024

El Chocón dam is located on Limay River in the province of Neuquén (Argentina) and is one of the most important in the country and in Latin America due its reservoir capacity. Currently, the dam is at full operation stage, while its structural health is monitored through a significant number of instruments installed in the dam body and its foundation. In the sector of the closure of the dam on its left margin, the measurements of some piezometers that monitor the deep rock foundation, showed some changes that gave rise to the hypothesis of the advance of wet front, despite fact that the work has practically 50 years from commissioning. To confirm or rule out this hypothesis, research work was started using the 2D electrical tomography method. The methodology was selected based on the good correlation that exists between the electrical resistivity and the volumetric content of water in a rock formation. Tomographic image obtained made it possible to determine different sectors in which wet front is detected and to define its extension, also evidencing a good correlation with what was recorded in the rock auscultation instruments, confirming the slow advance of wet front to downstream.
Detection of colorectal cancer and advanced neoplasia during first surveillance interval after detection of adenomas in fecal immunochemical test cancer screening: a nationwide study
Authors: Larsen Pernille T. , Jørgensen Susanne F. , Hagemann-Madsen Rikke , Rasmussen Morten , Andersen Berit , Njor Sisse H.
Published: July 2024

Background Adenoma surveillance guidelines are based on non-fecal immunochemical test (FIT)-based screening settings. However, colorectal cancer (CRC) risk may be different in FIT-positive screening populations. We evaluated the CRC and advanced adenoma risk within the recommended surveillance periods in the Danish FIT-based CRC screening program for participants with intermediate or high risk adenomas according to 2010 European guidelines. Furthermore, we estimated CRC risk for those who were not recommended surveillance according to European Society of Gastrointestinal Endoscopy (ESGE) 2020 guidelines.

Methods Using nationwide health registries, we identified 17 936 FIT-screening participants from 2014–2017 with adenomas undergoing surveillance (high risk 1 year, intermediate risk 3 years). Participants with a follow-up examination were included (N = 10 068). Relative risk (RR) of CRC and advance adenoma was compared between intermediate and high risk groups and between intermediates who were recommended surveillance (S) or no surveillance (NS) according to 2020 ESGE guidelines.

Results During surveillance, CRC occurred in 0.59% of the high risk group and 1.11% of the intermediate risk group (RR 0.53 [95%CI 0.34–0.84]). The high risk group had a 24% increased risk of advanced adenoma. CRC occurred in 1.69% of the intermediateNS group and 0.87% of the intermediateS group (RR 1.94 [95%CI 1.18–3.21]), and RR for advanced adenoma was 1.19 (95%CI 1.03–1.37).

Conclusion CRC detection was lower among participants rated at higher risk at initial CRC screening. Findings at first screen-derived colonoscopy might not be as good a predictor of CRC risk in a FIT-positive screening population.
Current Treatments and Future Directions for Facial Paralysis
Authors: Leckenby Jonathan , Sweitzer Keith , Olsen Timothy , Mayorga-Young Danielle , Milek David , Grobbelaar Adriaan
Published: July 2024

Facial palsy is a condition that affects the facial nerve, the seventh of the 12 cranial nerves. Its main function is to control the muscles of facial expression. This involves the ability to express emotion through controlling the position of the mouth, the eyebrow, nostrils, and eye closure. The facial nerve also plays a key role in maintaining the posture of the mouth and as such, people with facial paralysis often have problems with drooling, speech, and dental hygiene.

Due to the devastating effects on the quality of life of individuals with facial palsy, there are a multitude of various treatment options for the paralyzed face. This article reviews current management strategies and points towards promising future directions for research in the field of facial reanimation.
Necrotic Liver Lesion Resolution: Another Mode of Liver Regeneration
Authors: Chen Cheng , Feng Dechun , Wang Yang , Yao Tiantian , Mackowiak Bryan , Gao Bin
Published: July 2024

The liver has the great ability to regenerate after partial resection or injury, and the mechanisms underlying liver regeneration have been extensively investigated. Interestingly, acute liver injuries triggered by various etiologies are associated with the formation of necrotic lesions, and such necrotic lesions are also rapidly resolved. However, how necrotic liver lesions are repaired has not been carefully investigated until recently. In this review, we briefly summarize the spatiotemporal process of necrotic liver lesion resolution in several liver injury models including immune-mediated liver injury and drug-induced liver injury. The roles of liver nonparenchymal cells and infiltrating immune cells in controlling necrotic liver lesion resolution are discussed, which may help identify potential therapies for acute liver injury and failure.
A π-Stacked Highly Stable, Insensitive, Energy-Containing Material with a Useful Planar Structure
Authors: Zhang Peng-cheng , Lin Qiuhan , Liu Shuliang , Qi Yuan
Published: July 2024

π-Stacking is common in materials, but different π–π stacking modes remarkably affect the properties and performances of materials. In particular, weak interactions, π-stacking and hydrogen bonding often have a significant impact on the stability and sensitivity of high-energetic compounds. A fused [5,7,5]-tricyclic energetic compound with a conjugated structure has been designed and synthesized. 4H-[1,2,5]Oxadiazolo[3,4-e][1,2,4]triazolo[3,4-g][1,2,4]triazepin-8-amine is obtained in 48% yield from 3-amino-4-carboxy-1,2,5-oxadiazole through an efficient two-step reaction. Owing to its layered planar structure and weak π interactions between layers, 4H-[1,2,5]oxadiazolo[3,4-e][1,2,4]triazolo[3,4-g][1,2,4]triazepin-8-amine exhibits high thermal stability (T
d = 318 °C), low sensitivity (IS = 40 J, FS = 360 N), and relatively excellent detonation performance (D = 7059 ms–1, P = 20.2 GPa). This detonation performance is superior to that of the conventional explosive TNT. The developed procedure provides a new method for the synthesis of fused ring compounds.
Rate of Depression, Anxiety and Stress among Interns/House Officers in Nigeria
Authors: Muhammad Daha Garba , Gbonjubola Yusuff Tunde , Jamiu Monsur Olalekan , Abiodun Adesola Oyinkansola
Published: July 2024

Background Medical school is one of the most academically and emotionally demanding programs. The mandatory house job and internship year adds to the already high level of stress associated with medical school. The amount of time and effort invested is considerable. This dedication could be harmful to the young trainees' health, causing worry, despair, and stress. This study was undertaken to determine the rate of anxiety, depression, and stress among interns and house officers in Nigeria.

Materials and Methods This is a descriptive cross-sectional survey in which 138 participants were conveniently recruited. The study used a self-report questionnaire with two sections that took approximately 10 minutes to complete. The first section collected sociodemographic information of the participants and the Depression, Anxiety, and Stress Scale (DASS-21) was used in the second segment to assess depression, anxiety, and stress.

Results The rate of depression, anxiety, and stress among the participants in this study is 37.3, 42.5, and 15.7%, respectively. In this study, only duration of training has significant association with depression and stress (p < 0.05). However, all other sociodemographic variables showed no significant association with depression, anxiety, and stress (p > 0.05).

Conclusion The significantly high level of depression, anxiety, and stress found among the participants revealed that depression, anxiety, and stress are of public mental health concern. These may have negative effects on cognitive functioning, learning, and patient care.