Experimental Modeling Approach Research Articles

Deciphering the CO2 hydrates formation dynamics in brine-saturated oceanic sediments using experimental and machine learning modelling approach

One of the potential strategies for limiting global warming is capturing excess amounts of industry CO2 emissions and sequestrating it inside the oceanic sediments as CO2 hydrates. The seabed consists of sediments with different porosity and sizes, which can significantly impede the kinetics of CO2 hydrates. To address these challenges, in this novel work the CO2 hydrate kinetics and morphologies have been investigated in brine-rich [3.5 wt% NaCl] coarse sediments [porosity = 0.28, Ø =0.5-1.5 mm], granule sediments [porosity = 0.43, Ø =1.5-3 mm] and dual sediments [coarse + granules] inside a high-pressure reactor [3.5 MPa, 1-2 oC] with artificial seabed. According to the key experimental results, the water-to-hydrate conversion [%] was estimated to be 67.24 (± 3.02) % for coarse sediments, 49.58 (± 4.97) % for dual sediments (coarse + granules), and 27.68 (± 5.21) % for granules. In-situ Raman spectroscopy was used to evaluate the real-time solubility of CO2 [0.023 mol/mol], and image processing thresholding was used to identify CO2 hydrate distribution patterns. A mathematical model was proposed as a major contribution to predict CO2 hydrates kinetics in sediments, using 94,203 data points. The model was trained via a supervised machine-learning [ML] algorithm and can predict CO2 hydrate kinetics with an AARD of 7.54-8.47%.

Nonlinear flutter in a wind-excited double-deck truss girder bridge: experimental investigation and modeling approach

Nonlinear flutter in a wind-excited double-deck truss girder bridge: experimental investigation and modeling approach

Thermodynamics of Polymer Drug Interactions: An Influential Factor for the Development of a Stable Drug Delivery System

Polymer-drug interactions play a pivotal role in the design and optimization of drug delivery systems. Thermodynamic principles, such as enthalpy, entropy and free energy, govern these interactions and significantly influence the stability, efficacy and release profiles of the drug-polymer complexes. In this review we explore the role of thermodynamics in drug-polymer binding, focusing on non-covalent interactions, including van der Waals forces, hydrogen bonding, ionic interactions and hydrophobic effects. These interactions affect the drug encapsulation efficiency, release kinetics and the overall stability of the delivery system. Understanding the balance between the various thermodynamic forces helps in the rational design of advanced drug delivery platforms, such as nanoparticles, micelles and hydrogels, which rely on optimized drug-polymer affinity. Our review further delves into the experimental techniques and modeling approaches used to characterize these interactions, such as isothermal titration calorimetry (ITC), molecular dynamics (MD) simulations and surface plasmon resonance (SPR). By examining these thermodynamic foundations, we believe this article provides insights into developing more efficient and stable drug delivery systems that ensure targeted release, enhanced bioavailability and reduced side effects.

Experimental and molecular modeling approach on the corrosion behavior of mild steel in HCl solution with quinoxaline inhibitors

Two new quinoxaline derivatives namely (E)-3-(2-chlorostyryl)quinoxalin-2(1H)-one (CSQO) & (E)-3-(2-(thiophen-2-yl)vinyl)quinoxaline-2(1H)one (TVQO) were synthesized and identified through the following methods like infrared (IR) analysis, mass spectrometry,1H NMR and 13C NMR. Weight loss, electrochemical techniques [PDP&SIE], surface analytical techniques [SEM&UV-Visible], quantum chemical calculations [DFT], and MD simulations have all been used to examine the effectiveness of CSQO and TVQO in preventing the corrosion of mild steel. According to the findings of the experiments, the inhibitors CSQO and TVQO effectively suppress the corrosion of mild steel in 1 M HCl solution, with maximum corrosion inhibition of 97.0 and 95.5% at 10−3 M for CSQO and TVQO, respectively. Based on PDP investigations, CSQO and TVQO function as mixed-type inhibitors, and their adsorption on the MS surface follows the Langmuir adsorption isotherm and the mode of adsorption is chemisorption. Both surface investigations (SEM and UV-Visible) have validated the protective layer that developed on the metal surface. DFT calculations and MD simulations were used to study the association between inhibitor molecular structure [CSQO and TVQO] and inhibitory efficacy, and they closely match the experimental findings.

Research progress on single-cell expression quantitative trait loci.

Expression quantitative trait loci (eQTL) represent genetic variants that regulate gene expression levels. eQTL analysis has become a crucial method for identifying the functional roles of disease-associated genetic variants in the post-genome-wide association study (GWAS) era, yielding numerous significant discoveries. Traditional eQTL analysis relies on whole-genome sequencing combined with bulk RNA-seq, which obscures gene expression differences between cells and thus fails to identify cell type- or state-dependent eQTL. This limitation makes it challenging to elucidate the roles of disease-associated genetic variants under specific conditions. In recent years, with the development and widespread application of single-cell RNA sequencing (scRNA-seq) technology, scRNA-seq-based eQTL (sc-eQTL) research has emerged as a focal point. The advantage of this approach lies in its ability to leverage the resolution and granularity of single-cell sequencing to uncover eQTL that are dependent on cell type, cell state, and cellular dynamics. This significantly enhances our ability to analyze genetic variants associated with gene expression. Consequently, it holds substantial significance for advancing our understanding of the formation of complex organs and the mechanisms underlying disease onset, progression, intervention, and treatment. This review comprehensively examines the recent advancements in sc-eQTL studies, focusing on their development, experimental design strategies, modeling approaches, and current challenges. The aim is to offer researchers novel perspectives for identifying disease-associated loci and elucidating gene regulatory mechanisms.

Evaluating the impact of rail surface roughness post-grinding: An experimental and elastoplastic modelling approach

Grinding is regularly conducted on railway tracks to prevent crack propagation and surface deterioration. However, grinding can introduce roughness on rail surfaces, potentially leading to stress and strain concentration that increase the likelihood of crack initiation. This paper proposes the utilization of surface roughness obtained by replicating the ground rail surface to assess its impact on train wheel-rail interactions. A novel approach which integrates the replicated roughness into an elastoplastic contact model, allows for a detailed assessment of its effects on contact pressure, and residual strain and stress distributions. The findings highlight the importance of considering surface roughness in predictive maintenance planning for railway infrastructure, as it can significantly influence the structural integrity and long-term performance of the track system.

An integrated experimental-modeling approach to identify key processes for carbon mineralization in fractured mafic and ultramafic rocks.

Controlling atmospheric warming requires immediate reduction of carbon dioxide (CO2) emissions, as well as the active removal and sequestration of CO2 from current point sources. One promising proposed strategy to reduce atmospheric CO2 levels is geologic carbon sequestration (GCS), where CO2 is injected into the subsurface and reacts with the formation to precipitate carbonate minerals. Rapid mineralization has recently been reported for field tests in mafic and ultramafic rocks. However, unlike saline aquifers and depleted oil and gas reservoirs historically considered for GCS, these formations can have extremely low porosities and permeabilities, limiting storage volumes and reactive mineral surfaces to the preexisting fracture network. As a result, coupling between geochemical interactions and the fracture network evolution is a critical component of long-term, sustainable carbon storage. In this paper, we summarize recent advances in integrating experimental and modeling approaches to determine the first-order processes for carbon mineralization in a fractured mafic/ultramafic rock system. We observe the critical role of fracture aperture, flow, and surface characteristics in controlling the quantity, identity, and morphology of secondary precipitates and present where the influence of these factors can be reflected in newly developed thermo-hydro-mechanical-chemical models. Our findings provide a roadmap for future work on carbon mineralization, as we present the most important system components and key challenges that we are overcoming to enable GCS in mafic and ultramafic rocks.

The archaeal family 3 polyphosphate kinase reveals a function of polyphosphate as energy buffer under low energy charge.

Inorganic polyphosphate, a linear polymer of orthophosphate residues linked by phosphoanhydride bonds, occurs in all three domains of life and plays a diverse and prominent role in metabolism and cellular regulation. While the polyphosphate metabolism and its physiological significance have been well studied in bacteria and eukaryotes including human, there are only few studies in archaea available so far. In Crenarchaeota including members of Sulfolobaceae , the presence of polyphosphate and degradation via exopolyphosphatase has been reported and there is some evidence for a functional role in metal ion chelation, biofilm formation, adhesion and motility, however, the nature of the crenarchaeal polyphosphate kinase is still unknown. Here we used the crenarchaeal model organism Sulfolobus acidocaldarius to study the enzymes involved in polyphosphate synthesis. The two genes annotated as thymidylate kinase ( saci_2019 and saci_2020 ), localized downstream of the exopolyphosphatase, were identified as the missing polyphosphate kinase in S. acidocaldarius ( Sa PPK3). Thymidylate kinase activity was confirmed for Saci_0893. Notably Saci_2020 showed no polyphosphate kinase activity on its own but served as regulatory subunit (rPPK3) and was able to enhance polyphosphate kinase activity of the catalytically active subunit Saci_2019 (cPPK3). Heteromeric polyphosphate kinase activity is reversible and shows a clear preference for polyP-dependent nucleotide kinase activity, i.e. polyP-dependent formation of ATP from ADP (12.4 U/mg) and to a lower extent of GDP to GTP whereas AMP does not serve as substrate. PPK activity in the direction of ATP-dependent polyP synthesis is rather low (0.25 U/mg); GTP was not used as phosphoryl donor. A combined experimental modelling approach using quantitative 31 P NMR allowed to follow the reversible enzyme reaction for both ATP and polyP synthesis. PolyP synthesis was only observed when the ATP/ADP ratio was kept high, using an ATP recycling system. In absence of such a recycling system, all incubations with polyP and PPK would reach an equilibrium state with an ATP/ADP ratio between 3 and 4, independent of the initial conditions. Structural and sequence comparisons as well as phylogenetic analysis reveal that the S. acidocaldarius PPK is a member of a new PPK family, named PPK3, within the thymidylate kinase family of the P-loop kinase superfamily, clearly separated from PPK2. Our studies show that polyP, in addition to its function as phosphate storage, has a special importance for the energy homeostasis of S. acidocaldarius and due to its reversibility serves as energy buffer under low energy charge enabling a quick response to changes in cellular demand.

Motivation and Play Activities for Children's Basic Movements

Delays in basic movements during early childhood represent a challenge that must be addressed by sports professionals. This research aims to describe how play and motivation relate to children's basic movements, implementing an experimental model approach. The sample participants were children who were still in primary school, with an average age of 11.09 ± 0.73 years. Data were collected using a training motivation questionnaire and the Scott motor ability test, which consisted of basketball throw, 4-second run, wall pass, and long jump. Data were analyzed using a two-way factorial ANOVA test. The research results show that the kasiti ball training model is more effective than fortification training. Furthermore, there is an interaction between the form of training and motivation: the basic movements performed in the kasiti ball training are superior to the strengthening ones for children with high training motivation, while the baseball training is better than the of strength for those with low motivation. This finding is important as it informs children's basic movement skills through specific exercises. Keywords: Children, basic movements, motivation, forms of play.

Impact of viscoelasticity on the stiffness of polymer nanocomposites: Insights from experimental and micromechanical model approaches

The mechanical properties of BaTiO3 filled HDPE nanocomposites are studied by experimental and numerical approaches. First, the viscoelastic behavior of neat HDPE is highlighted experimentally in tensile and relaxation tests. A method is then proposed to define a constitutive viscoelastic law representative of this behavior at different tensile crosshead speeds at room temperature. Afterward, this law is implemented in a finite-element-based micromechanical model representing the BaTiO3 filled HDPE nanocomposites with different filler amounts. The experimental and numerical results are further compared. Both the experiments and numerical simulations confirm the viscoelastic behavior of the polymer nanocomposite. For nanocomposites with filler concentrations up to 20 %, the error between the experimental and numerical findings remains less than 8 %, confirming that the model represents well the composite behavior for low and moderate filler amounts. The proposed strategy can be applied to other polymer composites in order to predict the complete mechanical behavior of viscoelastic composite materials.

Thermal response of freshwater ciliates: Can they survive at elevated lake temperatures?

Abstract Ciliates are a well‐defined, species‐rich, versatile group of heterotrophic and mixotrophic protists. Their response to increased temperature during global warming is critical for the structure and functioning of freshwater food webs. I conducted a meta‐analysis of the literature from field studies and experimental evidence to assess the parameters characterising the thermal response of freshwater ciliates. The shape of the thermal performance curve predicts the ciliates' survival at supraoptimal temperatures (i.e., the width of the thermal safety margin). The ciliates' typical thermal safety margin is c. 5°C. More than two‐thirds of the freshwater ciliates dwelling permanently or occasionally in the pelagial cannot survive at temperatures exceeding 30°C. Likewise, cold‐stenothermic species, which represent a significant fraction of euplanktonic ciliates, cannot survive by evolutionary adaptation to rapidly warming environments. The statistical analysis revealed that the ciliates' thermal performance is affected by their planktonic lifestyle (euplanktonic vs. tychoplanktonic), ability to form cysts and nutritional ecology. Bactivorous ciliates have the widest temperature niche, and algivorous ciliates have the narrowest temperature niche. Phenotypic plasticity and genetic variation, favouring the selection of pre‐adapted species in a new environment, are widespread among freshwater ciliates. However, the lack of evidence for the temperature optima and imprecisely defined tolerance limits of most species hampers the present analysis. The extent of acclimation and adaptation requires further research with more ciliate species than the few chosen thus far. Recent eco‐evolutionary experimental work and modelling approaches have demonstrated that the ciliates' thermal responses follow general trends predicted by the metabolic theory of ecology and mechanistic functions inherent in enzyme kinetics. The present analysis identified current knowledge gaps and avenues for future research that may serve as a model study for other biota. Thermal adaptation may conflict with adaptation to other stressors (predators, food availability, pH), making general predictions on the future role of freshwater ciliates in a warmer environment difficult, if not impossible, at present.

Antioxidant Potential of Tisochrysis lutea through Urea-Based Nanonutrient Enrichment: Experimental Modeling and Computational Approach

Antioxidant Potential of Tisochrysis lutea through Urea-Based Nanonutrient Enrichment: Experimental Modeling and Computational Approach

Dynamics of Saltwater Intrusion in a Heterogeneous Coastal Environment: Experimental, DC Resistivity, and Numerical Modeling Approaches

Saltwater intrusion (SWI) is a critical concern affecting coastal groundwater sources due to natural and anthropogenic activities. The health of coastal aquifers is deteriorated by excessive SWI, mainly caused by the disturbance of the freshwater–saltwater equilibrium due to the escalating population, climate change, and the rising demand for freshwater resources for human activities. Therefore, gaining insight into the dynamics of SWI is crucial, particularly concerning the various factors that influence the intrusion mechanism. The present study focuses on the experimental simulation of saltwater in freshwater aquifers, considering boundary conditions and density-dependent effects. Two geological scenarios within coastal environments were investigated: First, a uniform, homogeneous case consisting of only sand, and second, a heterogeneous case in which layers of sand, clay, and sand mixed with pebbles are used. During the experiment, DC resistivity sounding data, as part of a widely recognized geophysical method, were collected and subsequently inverted to determine the depth of the freshwater–saltwater interface (FSWI). A finite element analysis was employed to generate numerical models based on experimental feedback. Further, for validation purposes, electrical resistivity tomography (ERT) data were collected from two distinct locations: near the seacoast and an aquaculture area. The ERT results show the presence of salinity intrusion in the study area, attributed mainly to groundwater overpumping and fish farming practices. The experimental findings indicate that the advancement of saltwater is affected by the geological properties of the media they traverse. The porosity (ϕ) and permeability (k) of the geological layer play a crucial role during the passage of saltwater flux into freshwater aquifers. The FSWI deviated along the clay boundary and hindered the easy passage of saltwater into surrounding layers. The alignment of experimental, numerical, and geophysical data suggests that this integrated approach could be valuable for studying SWI and can be applied in different geological settings, including tidal flats and alluvial plains.

The spatial planning of housing and urban green space: A combined stated choice experiment and land-use modeling approach

Urban green space (UGS) is receiving increasing attention as a means to make cities better adapted to climate change and to create high-quality living environments for citizens. The spatial planning of UGS generally asks a trade-off between optimizing land-use and accessibility characteristics which may differ between housing types. In this paper, we use a stated choice experiment to estimate residential location preferences related to neighborhood land-use, UGS and accessibility characteristics in the framework of a land-use model. A national sample of 394 Dutch homeowners participated in the experiments and mixed logit models were estimated by housing type distinguishing detached, row houses and apartments. The estimation results show that trade-offs made between a green neighborhood and accessibility to urban amenities tend to differ between the housing types. The estimates are used as parameters in a housing land-use allocation model. An application of the model to a residential area development problem shows that creating green buffers along road infrastructure is the most beneficial way of allocating UGS considering the housing value for residents. The application further shows that apartments benefit more strongly from UGS in the neighborhood than from high accessibility of urban amenities compared to detached and row houses. Finally, we find that the optimal spatial allocation of UGS depends on whether maximizing housing market-value or residents’ utility is the prime objective.

Evaluating the effect of different diaphragm wall cracking scenarios on seepage and slope stability in Earth dams using experimental and numerical modeling approaches

BackgroundSeepage control measures are essential in earth dams to enhance their safety against seepage and slope failures. A diaphragm is a thin impervious wall that is used in the core area of the dam to prevent the seepage of water. Any crack in the diaphragm can reduce its efficiency and threaten the safety and stability of the dam. Extensive evaluation of the influence of diaphragm fracturing on dam safety is required to establish a safe design and offer the appropriate measures. This study investigates the effect of diaphragm cracking on the safety of the dam for seepage and slope stability. A permeability tank is first used to validate the numerical model; then, different scenarios for cracked diaphragm walls are studied numerically. The crack’s height, width, direction, and number are all investigated. The effect of having a downstream horizontal blanket drain with cracked internal diaphragms is also evaluated.ResultsThe results showed that the internal diaphragm enhances the safety of earth dams as it reduced the seepage discharge by 98% and increased the downstream slope safety by 34%. Considering the development of a crack in the internal diaphragm, the most critical location was at the base of the dam, wider cracks were more destructive, and the most critical direction was the horizontal crack. The fracturing of the diaphragm at multiple locations proved to be detrimental to the safety of the dam. Having three cracks caused the seepage discharge to reach 74% of its value for no diaphragm, the pore water pressure to raise drastically, and the downstream critical factor of safety to be higher than the case of no diaphragm by 8% only.ConclusionsAccording to the findings, it is advised to continuously monitor the components of diaphragm-type earth dams and perform the necessary maintenance works whenever any sign of damage or water seepage appears. Furthermore, using a well-graded horizontal drain of sufficient length and high permeability with the internal diaphragm is highly recommended as a mitigation measure if diaphragm fracturing occurs. This helps to quickly release the seeping water and keep the phreatic line away from the downstream slope.Graphical abstract

Correlating mechanical properties of Al/Al bimetal composite and its constituents using combined experiment and microstructure-based multiscale modeling approach

A combined experiment and multiscale modeling approach was presented to correlate the mechanical properties of a roll-bonded AA1050/AA3004 bimetal clad sheet and constituents. The mechanical responses of the 2-ply AA1050/AA3004 and constituents were measured under various loading conditions. For the measurements, each constituent was separated from the clad sheet using electrical discharge machining and uniaxial tensile tests. Continuum-scale yield functions such as isotropic von Mises and anisotropic/non-quadratic Yld2000-2d were developed for the two constituents and the bimetal clad sheet. A grain-scale crystal plasticity finite element (CPFE) simulations were also performed incorporated with newly developed representative volume element considering measured microstructural attributes. These CPFE predictions were used to identify the anisotropy coefficients for Yld2000-2d. Using the identified yield functions, finite element modeling was followed in which the mechanical properties of each constituent sheet were addressed separately. This is a new approach developed in the current work and it enables a fundamental correlation between multilayered material and its constituents. The mechanical properties of the bimetal clad sheet under the uniaxial tensions were predicted using those of the constituents and compared with calculations based on known rule of mixture (ROM) approach. The two approaches well reproduced stress–strain curves and r–value evolutions. The two FE modeling approaches were also applied to an independent test (i.e., the limiting dome height). The predictions were in good agreement with the experimental data. Finally, the mechanical properties of the bimetal clad sheet and constituents were correlated, and proper modeling scheme for multilayered materials is proposed.

Repurposing plastic waste: Experimental study and predictive analysis using machine learning in bricks

The construction industry significantly contributes to environmental degradation and resource depletion. This paper investigates the use of waste plastic from post-consumer and post-industrial sources as a sustainable alternative in brick manufacturing. By substituting plastic waste for traditional materials like clay or cement, the ecological footprint of brick production is reduced, and plastic pollution is mitigated by diverting waste from landfills and oceans. This study employs dual approach of experimentation as well as machine learning for assessing the strength behaviour of bricks enhanced with plastic, emphasising compressive strength, durability, thermal insulation, and moisture resistance. Utilization of Chlorinated Polyvinyl Chloride (CPVC) for Waste plastic bricks (WPB) was done by replacing cement and sand in different proportions i.e. 10 %, 20 %, 30 %, 40 %, and 50 % of fly ash bricks The best performance was observed at 30 % replacement of sand with waste CPVC. A Deep Neural Network (DNN) model also predicted compressive strength and water absorption, identifying key material components influencing brick properties through SHAP value analysis. This combined experimental and predictive modelling approach demonstrates the potential of waste plastic in creating lightweight, sustainable building materials for structural applications, contributing to sustainable construction practices.

Assessment of flexural performance of reinforced mud sandwich panels: experimental and numerical modeling approach

Assessment of flexural performance of reinforced mud sandwich panels: experimental and numerical modeling approach

Multidimensional hybrid software-in-the-loop modeling approach for experimental analysis of a floating offshore wind turbine in wave tank experiments

A hybrid experimental modeling approach for floating offshore wind turbines (FOWTs) in a wave tank is presented. The method called real-time hybrid method (RTHM) or software-in-the-loop (SIL) includes physically reproduced hydrodynamic loads in the wave tank, with a Froude-scaled model while aerodynamic loads are reproduced on the model by an actuator. The force is applied on the tower top and calculated by a numerical simulation running in real-time as a function of the measured velocity and position of the physical model. Couplings between the platform motion, the aerodynamic loads and the wind turbine controller are hence accounted for. A new SIL actuator enabling the reproduction of a multi-component force at the tower top of an experimental scaled wind turbine model is developed, and the quantification of the accuracy of the replicated forces is studied. The test case includes a floating spar platform carrying a 10 MW horizontal axis wind turbine. The results show that this SIL actuator can accurately replicate the low and wave-frequency aerodynamic loads, which are essential for wave tank testing. Lastly, a case study of the wind turbine model in colinear and misaligned wind and wave conditions is presented, showing 3D forces and induced motions.

Retention of 226Ra in the sandy Opalinus Clay facies from the Mont Terri rock laboratory, Switzerland

The safety assessment of deep geological disposal of nuclear waste requires a sound understanding of radionuclide retention in the repository host rocks. Here, we investigate the retention behaviour of the safety relevant radionuclide 226Ra in the heterogeneous sandy facies of the Opalinus Clay (OPA-SF) at the Mont Terri underground rock laboratory. Various rock samples were selected from a drill core (BAD-1) located in the lower sandy facies, which were representative for its textural and mineralogical heterogeneity. The samples were carefully characterized with respect to mineralogy and chemistry using X-Ray diffraction and electron microscopy. The amounts of quartz, carbonates and clay minerals in the samples ranged between 58 wt.% – 65 wt.%, 13 wt.% – 35 wt.% and 5 wt.% – 25 wt.%, respectively, underpinning the mineralogical heterogeneity. Rare (Ba,Sr)-sulphate precipitates were identified in the clay matrix by electron microscopy. The uptake behaviour of Ra was evaluated using batch sorption experiments. Corresponding to the mineralogical variability of the rock samples, the measured distribution ratios Rd for the 226Ra retention varied between 20 L kg−1 and 260 L kg−1 after 120 days. The experimental results and thermodynamic modelling approaches suggest that various processes contribute to the uptake of 226Ra on different time scales: fast cation exchange and surface complexation reactions by clay minerals and the (slower) formation of solid solutions during recrystallisation of (Ba,Sr)-sulphates as well as retention by carbonate minerals; the latter mechanism still requiring further investigation.