Experimental Approach Research Articles

Accurate prediction of aging effects on microstructure evolution and related mechanical strength of Mg-Zn alloys via multiscale simulations

Age strengthening is a common method to achieve superior mechanical properties employed in magnesium (Mg) alloys. However, the experimental approaches to examine the aging effects on mechanical properties are primarily based on trial and error, posing challenges for the design and development of high-strength Mg alloys. A promising solution to address this challenge is to establish an accurate prediction model for the aging effects on Mg alloys, covering the evolution of microstructure and corresponding mechanical properties. This paper introduces a multiscale simulation approach to accurately predict the aging effects on the Mg-2.3Zn (at.%) alloy. To begin, we establish a phase field model to simulate the microstructure evolution at 150 ℃, demonstrating precipitate growth during aging in alignment with experimental observations. Secondly, based on the microstructures obtained from phase field simulations, the corresponding yield strength is determined through finite element method simulations. The simulation successfully captures the peak-aged behavior of yield strength during aging, resulting in a yield strength of 167 MPa at the peak-aged state, with a deviation of less than 5 % from experimental results. In-depth analysis indicates that the peak value of total yield strength arises from the interplay between solid solution strengthening and precipitate strengthening. Furthermore, precipitate strengthening reaches a peak value at a specific aging time, deviating from the total yield strength. This deviation is primarily attributed to the effect of precipitate size on shear strengthening during aging. This study presents a general method for predicting the microstructure evolution and corresponding mechanical properties of alloys through multiscale simulations, offering valuable insights for designing and predicting the performance of metallic alloys.

Differential responses to academic stress during the COVID-19 pandemic, transition, and the new normal period

This study aimed to investigate decreasing student academic stress in distance learning during the COVID-19 pandemic, transition period, and new normal era by giving a self-help module to students. This research employed an experimental approach with a group pre-test post-test design with quantitative analytics. The perceived academic stress scale (PASS) and module evaluation scale were utilized to assess students' academic stress levels and their understanding of the module. The subjects consisted of one male student and thirty-seven female students, as the school was dominated by female students. This study indicated that students' academic stress levels during the pandemic and the new normal were in the medium range (18.82 - 19.97). The results showed that there was no significant difference in academic stress between the pandemic and the transition period (t = 1.322, p 0.05) and the data between the pandemic and the new normal (t = -1.426, p 0.05), while between the transition period and the new normal, it showed a significant difference (t = -4.189, p 0.05). The study recommends that schools develop future guidance and counseling programs to help students cope with stress and build resilience. This study's findings can inform policy decisions and academic interventions to support students' mental health and academic success during challenging times.

Computational and experimental identification of keystone interactions in Ebola virus matrix protein VP40 dimer formation.

The Ebola virus (EBOV) is a lipid-enveloped virus with a negative sense RNA genome that can cause severe and often fatal viral hemorrhagic fever. The assembly and budding of EBOV is regulated by the matrix protein, VP40, which is a peripheral protein that associates with anionic lipids at the inner leaflet of the plasma membrane. VP40 is sufficient to form virus-like particles (VLPs) from cells, which are nearly indistinguishable from authentic virions. Due to the restrictions of studying EBOV in BSL-4 facilities, VP40 has served as a surrogate in cellular studies to examine the EBOV assembly and budding process from the host cell plasma membrane. VP40 is a dimer where inhibition of dimer formation halts budding and formation of new VLPs as well as VP40 localization to the plasma membrane inner leaflet. To better understand VP40 dimer stability and critical amino acids to VP40 dimer formation, we integrated computational approaches with experimental validation. Site saturation/alanine scanning calculation, combined with molecular mechanics-based generalized Born with Poisson-Boltzmann surface area (MM-GB/PBSA) method and molecular dynamics simulations were used to predict the energetic contribution of amino acids to VP40 dimer stability and the hydrogen bonding network across the dimer interface. These studies revealed several previously unknown interactions and critical residues predicted to impact VP40 dimer formation. In vitro and cellular studies were then pursued for a subset of VP40 mutations demonstrating reduction in dimer formation (in vitro) or plasma membrane localization (in cells). Together, the computational and experimental approaches revealed critical residues for VP40 dimer stability in an alpha-helical interface (between residues 106-117) as well as in a loop region (between residues 52-61) below this alpha-helical region. This study sheds light on the structural origins of VP40 dimer formation and may inform the design of a small molecule that can disrupt VP40 dimer stability.

Comprehensive Distortion Analysis of a Laser Direct Metal Deposition (DMD)-Manufactured Large Prototype Made of Soft Martensitic Steel 1.4313

Additive manufacturing (AM) by using direct metal deposition (DMD) often causes erratic distortion patterns, especially on large parts. This study presents a systematic distortion analysis by employing numerical approaches using transient–thermal and structural simulations, experimental approaches using tomography, X-ray diffraction (XRD), and an analytical approach calculating the buckling distortion of a piston. The most essential geometrical features are thin walls situated between massive rings. An eigenvalue buckling analysis, a DMD process, and heat treatment simulation are presented. The eigenvalue buckling simulation shows that it is highly dependent on the mesh size. The computational effort of the DMD and heat treatment simulation was reduced through simplifications. Moreover, artificial imperfections were imposed in the heat treatment simulation, which moved the part into the buckling state inspired by the experiment. Although the numerical results of both simulations are successful, the eigenvalue and DMD simulation cannot be validated through tomography and XRD. This is because tomography is unable to measure small elastic strain fields, the simulated residual stresses were overestimated, and the part removal disturbed the residual stress equilibrium. Nevertheless, the heat treatment simulation can predict the distortion pattern caused by an inhomogeneous temperature field during ambient cooling in an oven. The massive piston skirt cools down and shrinks faster than the massive core. The reduced yield strength at elevated temperatures and critical buckling load leads to plastic deformation of the thin walls.

Molecular-Scale Visualization of Steric Effects of Ligand Binding to Reconstructed Au(111) Surfaces.

Direct imaging of single molecules at nanostructured interfaces is a grand challenge with potential to enable new, precise material architectures and technologies. Of particular interest are the structural morphology and spectroscopic signatures of the adsorbed molecule, where modern probes are only now being developed with the necessary spatial and energetic resolution to provide detailed information at the molecule-surface interface. Here, we directly characterize the adsorption of individual m-terphenyl isocyanide ligands on a reconstructed Au(111) surface through scanning tunneling microscopy and inelastic electron tunneling spectroscopy. The site-dependent steric pressure of the various surface features alters the vibrational fingerprints of the m-terphenyl isocyanides, which are characterized with single-molecule precision through joint experimental and theoretical approaches. This study provides molecular-level insights into the steric-pressure-enabled surface binding selectivity as well as its effect on the chemical properties of individual surface-binding ligands.

Inclusiveness of Public Space: Experimental Approaches for the Revitalisation of Smaller Historic Urban Centres

In recent decades, many small Italian historic centers—particularly those situated inland—have witnessed a population decline due to inadequate access to public services and facilities. However, this depopulation has also allowed many centers to retain their distinctive features, now conferring upon them great cultural–historical and landscape value. New quality-of-life-centered economic models present the development of accessible public services as a necessity. Such a process could catalyze the recovery and growth of these centers, which continue to be deserted, regardless of their value. This paper considers combined solutions, including sustainable mobility, digital accessibility, networked services, and technological devices by applying them to trans-scalar studies with the goal of achieving sustainable outcomes. Some of the proposed solutions are the resolution of irregular ground levels, the use of electric vehicles, the creation of sharing models, the physical overhaul of routes, and the retrofitting of minor buildings for inclusive use in a comprehensive human-centered approach toward regeneration. This study is in line with the European guidelines for sustainable and intelligent mobility, whose goal is for at least one hundred European cities to become accessible to all and shifted to zero-emission mobility. Here, sustainable and smart mobility is understood not only as an improvement of environmental and social conditions, but also as a catalyst for environmental and social improvements and as an opportunity to enhance the livability of smaller, geographically isolated historic centers, moving toward a new economy of urban reclamation.

An experimental approach to the study of amber processing in the Neolithic: technical analysis of the Siliņupe amber assemblage, 4 th mill. BC, Latvia

Abstract Amber appears in the archaeological material of the Eastern Baltic region in the Middle Neolithic and continues in intensive use until the end of the Neolithic. Four major amber-working centres are known in the Eastern Baltic, the least studied of which is the settlement of Siliņupe (4th mill. BC). Not yet widely applied in research on Stone Age amber technologies, but very promising, is an analytical approach combining experimental archaeology and traceology to study processing choices made in specific production stages (i. e., individual technological elements), revealing that fine-grained sandstone was favoured for surface grinding, while flint tools were most widely used for shaping and surface treatment, distinguishing three techniques, namely shaving, scraping and pressure flaking, each identifiable by characteristic features. The study suggests that amber and flint processing were largely intertwined, as pressure flaking along with indirect percussion (used for splitting amber) derive from flint processing, and in the case of pressure flaking, required specific know-how.

Navigating the Green Transition: The Influence of Low-Carbon City Policies on Employment in China’s Listed Firms

This study explores the impact of China’s low-carbon city policy on employment using a quasi-natural experiment approach based on microdata from A-share listed companies (2007–2021). The findings indicate a statistically significant positive effect on employment levels, with an average increase of 7.27% in pilot compared to non-pilot cities. This boost in employment is primarily linked to green innovation, improved financing conditions, and increased sales activities. The policy disproportionately benefits high-skilled workers and positively affects employment in sales, research and development, and management while having a lesser impact on low-skilled and production workers. The employment gains are particularly significant in non-polluting sectors, regions with high marketization, and in the eastern areas of China. This study underscores the complex interplay between environmental policies and labor markets, emphasizing the need for skill differentiation in policy frameworks.

Tackling assay interference associated with small molecules.

Biochemical and cell-based assays are essential to discovering and optimizing efficacious and safe drugs, agrochemicals and cosmetics. However, false assay readouts stemming from colloidal aggregation, chemical reactivity, chelation, light signal attenuation and emission, membrane disruption, and other interference mechanisms remain a considerable challenge in screening synthetic compounds and natural products. To address assay interference, a range of powerful experimental approaches are available and in silico methods are now gaining traction. This Review begins with an overview of the scope and limitations of experimental approaches for tackling assay interference. It then focuses on theoretical methods, discusses strategies for their integration with experimental approaches, and provides recommendations for best practices. The Review closes with a summary of the critical facts and an outlook on potential future developments.

Trap-assisted tunneling in type II Ag2O/β-Ga2O3 self-powered solar blind photodetector

This study investigates a high-performance Ag2O/β-Ga2O3 self-powered photodiode through experimental and modeling approaches. Initially, a p-type Ag2O film, with a bandgap close to 4 eV and a hole density of approximately 6.35×1018 cm−3, was fabricated using faced two-target sputtering. The conduction and valence band offsets between Ag2O and β-Ga2O3 were determined via X-ray photoelectron spectroscopy, confirming a type II heterojunction. The device had a low on-voltage of 1.50 V and a low on-resistance of 5.40 mΩ.cm² in the dark. Subsequent illumination at 254 nm resulted in a notably high photocurrent, responsivity, and detectivity. To confirm the role of trap-assisted tunneling in the type II Ag2O/β-Ga2O3 heterojunction, Silvaco simulations were employed to model both the dark current and photocurrent. These simulations confirmed the prevalence of the trap-assisted tunneling mechanism, particularly through energy levels situated above the equilibrium Fermi level at the Ag2O/β-Ga2O3 interface, as described by the Danielsson model. Understanding the transport mechanism is paramount for the development of high-performance photodetectors. By comprehending how charge carriers navigate through the device and the influence of traps on their behavior, researchers can optimize device design and fabrication processes to enhance performance.

Competitive Video Game Exposure Increases Aggression Through Impulsivity in Chinese Adolescents: Evidence From a Multi-Method Study.

It is widely known controversies about the results of violent video game increase aggression. However, the role of competitive video games, has received less research attention, and the underlying mechanisms of their influence are unknown. This study aimed to expand the existing literature by systematically exploring the effects of competitive video game exposure on adolescent aggression and the mediating role of impulsivity. In so doing, three types of studies (collectively N = 2919, mean age varied from 13.75 to 15.44 years, with a balanced gender) combining cross-sectional, experimental, and longitudinal approaches, were conducted. The findings consistently show that competitive video game exposure increased adolescents' aggression and impulsivity. Also, impulsivity mediated the correlation and long-term effect of competitive video game exposure on aggression. However, the experimental study did not confirm the short-term mediating effect of impulsivity, which may be related to the type of aggression measured in the study. The results indicate that competitive video game exposure is an important antecedent factor for adolescent aggression, and impulsivity is the key underlying mechanism.

Electronic and Structural Disorder of the Epitaxial La0.67Sr0.33MnO3 Surface.

Understanding and tuning epitaxial complex oxide films are crucial in controlling the behavior of devices and catalytic processes. Substrate-induced strain, doping, and layer growth are known to influence the electronic and magnetic properties of the bulk of the film. In this study, we demonstrate a clear distinction between the bulk and surface of thin films of La0.67Sr0.33MnO3 in terms of chemical composition, electronic disorder, and surface morphology. We use a combined experimental approach of X-ray-based characterization methods and scanning probe microscopy. Using X-ray diffraction and resonant X-ray reflectivity, we uncover surface nonstoichiometry in the strontium and lanthanum alongside an accumulation of oxygen vacancies. With scanning tunneling microscopy, we observed an electronic phase separation (EPS) on the surface related to this nonstoichiometry. The EPS is likely driving the temperature-dependent resistivity transition and is a cause of proposed mixed-phase ferromagnetic and paramagnetic states near room temperature in these thin films.

Enhancing Corrosion Resistance of Mild Steel in 1M HCl: Investigation of New Benzoxazepine Derivatives Through Synthesis, Electrochemical Analysis, Surface Analysis, XPS, DFT, and Molecular Dynamics Simulation

AbstractThis research delineates the corrosion inhibitory efficiency of two newly synthesized benzoxazepine derivatives – [3,3‐dimethyl‐11‐phenyl‐3,4,5,11‐tetrahydrodibenzo[b,e] [1,4]oxazepine‐1(2 H)‐one (S1)] and [11‐(4‐chlorophenyl)‐3,3‐dimethyl‐3,4,5,11‐tetrahydrodibenzo[b,e][1,4]oxazepine‐1(2 H)‐one (S2)] – on mild steel in 1M HCl milieu. These derivatives were characterized by proton (1H NMR) and carbon (13C NMR) nuclear magnetic resonance spectroscopy. The experimental approach encompassed potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques. The corrosion inhibition efficacy of S1 and S2 was concentration‐dependent, with their efficiencies peaking at 92.0 % and 92.1 %, respectively, at a 10−3 M concentration. Surface characterization, conducted using scanning electron microscopy (SEM), energy‐dispersive X‐ray analysis (EDS), X‐ray diffraction (XRD), contact angle measurements, and X‐ray photoelectron spectroscopy (XPS), corroborated the formation of a protective barrier layer on the mild steel surface. Additionally, using an inductive approach, UV‐visible spectrometry was employed to elucidate the adsorption behaviors of these inhibitors on the steel surface. Density functional theory (DFT) and molecular dynamics (MD) simulations were utilized to decipher the interaction mechanisms and adsorption modalities, unveiling critical insights into the interactions of S1 and S2 with the mild steel surface. This comprehensive analysis highlights the robust corrosion inhibition potential of the newly synthesized benzoxazepine derivatives and illuminates their prospective utility as effective inhibitors for mild steel in corrosive environments.

Gouy phase effects on photocurrents in plasmonic nanogaps driven by single-cycle pulses

Abstract The investigation of optical phenomena in the strong-field regime requires few-cycle laser pulses at field strengths exceeding gigavolts per meter (GV/m). Surprisingly, such conditions can be reached by tightly focusing pJ-level pulses with nearly octave spanning optical bandwidth onto plasmonic nanostructures, exploiting the field-enhancement effect. In this situation, the Gouy phase of the focused beam can deviate significantly from the monochromatic scenario. Here, we study the effect of the Gouy phase of a pulse exploited to drive coherent strong-field photocurrents within a plasmonic gap nanoantenna. While the influence of the specific Gouy phase profile in the experiment approaches the monochromatic case closely, this scheme may be utilized to identify more intricate phase profiles at sub-diffraction scale. Our results pave the way for Gouy phase engineering at picojoule (pJ) pulse energy levels, enabling the optimization of strong-field optical phenomena.

Silvia De Marchi (1929) on numerical estimation: A translation and commentary.

Vittorio Benussi (1878-1927) is known for numerous studies on optical illusions, visual and haptic perception, spatial and time perception. In Padova, he had a brilliant student who carefully worked on the topic of how people estimate numerosity, Silvia De Marchi (1897-1936). Her writings have never been translated into English before. Here we comment on her work and life, characterized also by the challenges faced by women in academia. The studies on perception of numerosity from her thesis were published as an article in 1929. We provide a translation from Italian, a redrawing of its 23 illustrations and of the graphs. It shows an original experimental approach and an anticipation of what later became known as magnitude estimation.

Enhancement of Dielectric Properties of Echo-Friendly Cottonseed Oil-based Nanofluids for High Voltages

This study investigates the performance of nanofluid-based vegetable oil (VO) as an advanced dielectric medium for high-voltage equipment, with a specific focus on AC breakdown voltage (AC BDV). Nanofluids, comprising carefully selected nanoparticles (including Al2O3, TiO2, Fe2O3, SiO2, and Graphene) dispersed in cottonseed oil (CSO), offer a unique opportunity to enhance the dielectric properties of insulating fluids. Through a systematic experimental approach, AC BDV tests were conducted in Khwaja Fareed UEIT High Voltage Laboratory, and the results were compared to with traditional mineral oil (MO) for high-voltage equipment’s. The findings reveal significant improvements in the AC BDV of the nanofluid, demonstrating its enhanced electrical insulation capabilities. This study displays nanofluids based on VO as a promising alternative for enhancing high-voltage equipment's electrical performance while considering the environment. Implementing nanofluids effectively improves the dielectric properties of insulating fluids, contributing to advancements in high voltage equipment technology.

Predictive Modeling and Experimental Validation for Assessing the Mechanical Properties of Cementitious Composites Made with Silica Fume and Ground Granulated Blast Furnace Slag

Using sustainable cement-based alternatives, such as secondary cementitious raw materials (SCMs), could be a viable option to decrease CO2 emissions resulting from cement production. Previously conducted studies to determine the optimal mix designs of concrete primarily focused on either experimental approaches or empirical modeling techniques. However, in these experimental approaches, few tests could be performed for optimization due to time restrictions and lack of resources, and empirical modeling methods cannot be relied on without external validation. The machine learning-based approaches are further characterized by certain shortcomings, including a smaller number of data points, a less robust connection among the controlling factors, and a lack of comparative analyses among machine learning models. Furthermore, the literature on predicting the performance of concrete utilizing binary SCMs (silica fume (SF) and ground granulated blast furnace slag (GGBS)) is not available. Therefore, to address these drawbacks, this research aimed to integrate ML-based models with experimental validations for accurate predictions of the compressive strength (CS) and tensile strength (TS) of concrete that includes SF and GGBS as SCMs. Three soft computing techniques, namely the ANN, ANFIS, and GEP methods, were used for prediction purposes. Eight major input parameters, including the W/B ratio, cement, GGBS, SF, coarse aggregates, fine aggregates, superplasticizer, and the age of the specimens, were considered for modeling. The validity of the established models was assessed by using external experimental validation criteria, statistical metrics, and performance measures. In addition, sensitivity and parametric analyses were performed. Based on statistical measures, the ANFIS models outperformed other models with higher correlation and lower statistical error values. However, the GEP models exhibited superior performance compared to ANFIS and ANN with respect to the closeness of the RMSE, MAE, RSE, and R2 values between the training, validation, and testing sets for both the CS and TS models. Experimental validation showed strong evidence for the applicability of the proposed models with an R2 of 0.88 and error percentages of less than 10%. Sensitivity and parametric investigations demonstrated that the input variables exhibited the patterns described in the experimental dataset and the available literature. Hence, the proposed models are accurate, have better prediction performance, and can be used for design purposes.

Age-dependent deflection analysis of reinforced concrete beams incorporating high volume fly ash: experimental and ANN modeling approach

The research examines the influence of high-volume fly ash (HVFA) on reinforced concrete (RC) beam deflections over 180 days of continuous loading. The study comprises eight fly ash-based concrete mixes with varying fly ash ratios (0-60%). Experimental assessments are conducted on two load levels, corresponding to 25% and 50% of the initial cracking load. Thirty-two full-scale RC beams, each measuring (100×150×1800) mm, are fabricated for both load levels. Long-term deflections are monitored for all concrete mixes through sustained four-point bending tests at ages ranging from 1 to 180 days. A comparative analysis of the overall mid-span deflection between conventional and fly ash concrete RC beams is carried out against established design codes. It has been determined that high volume fly ash RC beams exhibited lesser contribution to creep and shrinkage deflection compared with conventional RC beams. Moreover, ANN modeling has also been carried out to propose a significant model helpful in predicting the total deflection of RC beams containing any fly ash content and at any age of concrete. The present study offers valuable insights for engineers and designers, facilitating the evaluation of age-dependent deflection patterns in RC beams constructed with reinforced high-volume fly ash concrete.

Flow dynamics and heat transfer analysis of a sweeping air jet – An experimental approach

Technological and environmental constraints are driving the development of enhanced heat transfer alternatives. In this context, the scope of this study encompasses sweeping jets generated by fluidic oscillators, which offer considerable potential for enhancing heat transfer. Initially, an experimental setup was developed to measure the flow velocity using a Laser Doppler Anemometer (LDA) and the heat transfer onto a target surface using a flux sensor. Moreover, videos capturing the free jet under various flow regimes were recorded using a Nikon® D850 camera. Concerning the flow dynamics of the sweeping jet, an upward trend in the estimated deflection angle of the jet and its oscillation frequency was noted at higher air flow rates. Heat transfer measurements on a surface indicated that an increase in air flow rate leads to improved heat transfer effectiveness of the jet. Finally, a comparison between the sweeping jet and the industry standard jet for surface cooling was carried out. This comparison revealed that the sweeping jet is highly sensitive to the flow regime at a distance from the plate of H/D= 6. In laminar flow, the sweeping jet outperforms the impinging jet in heat transfer performance. However, as the jet transitions to turbulent flow, the impinging jet exhibits superior thermal characteristics for enhancing heat transfer.

Carboxymethylated Rhizoma alismatis polysaccharides reduces the risk of calcium oxalate stone formation by reducing cellular inflammation and oxidative stress.

This study aims to elucidate the mechanism and potential of Rhizoma alismatis polysaccharides (RAPs) in preventing oxidative damage to human renal proximal tubule epithelial cells. The experimental approach involved incubating HK-2 cells with 100nm calcium oxalate monohydrate for 24h to establish a cellular injury model. Protection was provided by RAPs with varying carboxyl group contents: 3.57%, 7.79%, 10.84%, and 15.33%. The safeguarding effect of RAPs was evaluated by analyzing relevant cellular biochemical indicators.Findings demonstrate that RAPs exhibit notable antioxidative properties. They effectively diminish the release of reactive oxygen species, lactate dehydrogenase, and malondialdehyde, a lipid oxidation byproduct. Moreover, RAPs enhance superoxide dismutase activity and mitochondrial membrane potential while attenuating the permeability of the mitochondrial permeability transition pore. Additionally, RAPs significantly reduce levels of inflammatory factors, including NLRP3, TNF-α, IL-6, and NO. This reduction corresponds to the inhibition of overproduced pro-inflammatory mediator nitric oxide and the caspase 3 enzyme, leading to a reduction in cellular apoptosis. RAPs also display the ability to suppress the expression of the HK-2 cell surface adhesion molecule CD44.The observed results collectively underscore the substantial anti-inflammatory and anti-apoptotic potential of all four RAPs. Moreover, their capacity to modulate the expression of cell surface adhesion molecules highlights their potential in inhibiting the formation of kidney stones. Notably, RAP3, boasting the highest carboxyl group content, emerges as the most potent agent in this regard.