Experimental Techniques Research Articles

A Comparative Study of the Rheological Properties of a Fly Ash-Based Geopolymer Reinforced with PP Fiber for 3D Printing: An Experimental and Numerical Approach

The present study investigates the flow characteristics of fly ash-based (FA) geopolymers reinforced with polypropylene (PP) fibers during the extrusion process in three-dimensional printing. By applying the Herschel–Bulkley rheological model, this research provides a sound theoretical basis to understand the flow behavior of these materials under various conditions. The Herschel–Bulkley model describes the relationship between shear stress and the shear rate in non-Newtonian fluids, capturing yield stress and flow consistency. A combination of experimental and numerical techniques based on the Finite-Element Method (FEM) in COMSOL has been used in this study. The results of both experimental and simulation approaches are compared to examine the material behavior during extrusion. The experimental results indicate that PP fiber content significantly affects the rheological properties. Mixtures with high fiber content encountered issues such as high static yield. However, mixtures with moderate fiber content showed smoother extrusion processes, suggesting an optimal fiber addition range that balances mechanical properties and extrudability. The numerical simulations generally agreed with the experimental data up to a certain fiber content level, beyond which more complex interactions necessitate further model refinements. The investigation identified a 0.25% to 0.5% fiber content range that enhances performance without complicating the extrusion process, facilitating the production of properly printed structures.

Unraveling the complex interplay between elastic recovery, contact pressure, and friction on the flank face of the micro tools via plunging-type testing

A good understanding of the interplay between the cutting tool edge radius, elastic recovery, friction, and contact pressure is essential for better modeling of ploughing forces during micro-scale cutting. This study conducts plunging tests on an ultra-precision CNC with engineered tungsten carbide cutting tools on commercially pure titanium alloy. The cutting tool edge radius is prepared to be around 3.5–4 μm, which resembles those cutting tools used in micro scale machining. During plunging tests, the micro cutting tool is given a sinusoidal movement with an amplitude close to edge radius of the tool as the work material is rotated at a constant speed. The residual depth profiles of the webs corresponding to the commanded depths were investigated in detail to identify elastic recovery rate. The cutting and thrust force measurements during plunging experiments together with identified elastic recovery rate was employed in an analytical model of micro scale machining to obtain the variations of contact pressure and coefficient of friction as a function of commanded depth. Due to the scale of the experiments that were performed, the effects of surface topography of the cutting tool and possible alignment errors are also considered in the analytical model. A linear relationship between the contact pressure and elastic recovery has been identified during ploughing-dominated machining conditions for the work material and the cutting tool pair considered in this study. The proposed experimental technique is shown to be promising in terms of modeling ploughing forces during micro-scale cutting.

Seeing is believing – The application of Three-Dimensional modelling technologies to reconstruct the final hours in the life of an ancient Egyptian Crocodile

The application of non-invasive radiography (X-ray and CT) to an ancient Egyptian crocodile mummy demonstrated a high level of corporeal preservation achieved through artificial embalming. Analysis revealed numerous anomalies within the abdomen of the crocodile which merited further investigation using digital three-dimensional modelling technologies. Improving the clarity of the CT scan data enabled the authors to identify the anomalies which included a metal fish hook and a small fish. Segmentation of the CT scan data enabled the virtual extraction of the hook from within the confines of the mummy and its replication, firstly in plastic and then in its original material, bronze.Through the scientific analysis of the mummy, the authors reconstruct the biological biography and life history attributes of the animal, and consider the human-animal relationships and religious beliefs behind its post-mortem preservation. The study explores the application of the 3D technologies applied to archaeological materials and the novel implementation of experimental techniques to reproduce the anomaly. The investigation provided the ability to enhance the study, interpretation and display of the mummy; a matter of particular relevance in the case of mummified remains where anomalies are not directly visible. The authors consider the improved accessibility to cultural artefacts made possible through the application of enhanced visualisation techniques in the heritage sector.

Dynamics of thermal plumes for large spaces: A comparative study of in-situ smoke test and a CFD model

This study focuses on natural convection heat transfer in building heating and ventilation. Amid advancements in natural ventilation and a changing energy landscape, innovative heating methods are crucial. Thermal radiators play a key role in enhancing heat convection and understanding thermal plumes to optimize heating efficiency.This study investigates the use of coloured smoke sources to visualize thermal plume flow fields in real-scale (in-situ), naturally ventilated large spaces, distinguishing itself from most studies that prioritize enhancing thermal efficiency radiator. It offers a way for both qualitative and quantitative validation of a CFD model using passive scalars and experimental images to illustrate thermal plume propagation. This novel approach provides an effective way to visualize and understand thermal plumes in spaces where other experimental techniques are challenging to implement.Experimental results showed high consistency between measured and CFD values for velocity, temperature, and heat exchange, with differences below 10 %. The study unveiled a low impact of initial smoke source velocities on plume visualization. Using coloured smoke images to validate the CFD model yielded errors from 2.3 % to 14.5 %, proving the method’s reliability for both qualitative and quantitative analysis of plume propagation, offering valuable insights into air propagation in naturally ventilated spaces.

Comment on Martínez-Delgado et al. Using Absorption Models for Insulin and Carbohydrates and Deep Leaning to Improve Glucose Level Predictions. Sensors 2021, 21, 5273.

The paper "Using Absorption Models for Insulin and Carbohydrates and Deep Leaning to Improve Glucose Level Predictions" (Sensors2021, 21, 5273) proposes a novel approach to predicting blood glucose levels for people with type 1 diabetes mellitus (T1DM). By building exponential models from raw carbohydrate and insulin data to simulate the absorption in the body, the authors reported a reduction in their model's root-mean-square error (RMSE) from 15.5 mg/dL (raw) to 9.2 mg/dL (exponential) when predicting blood glucose levels one hour into the future. In this comment, we demonstrate that the experimental techniques used in that paper are flawed, which invalidates its results and conclusions. Specifically, after reviewing the authors' code, we found that the model validation scheme was malformed, namely, the training and test data from the same time intervals were mixed. This means that the reported RMSE numbers in the referenced paper did not accurately measure the predictive capabilities of the approaches that were presented. We repaired the measurement technique by appropriately isolating the training and test data, and we discovered that their models actually performed dramatically worse than was reported in the paper. In fact, the models presented in the that paper do not appear to perform any better than a naive model that predicts future glucose levels to be the same as the current ones.

Nanoarchitectonics of molecular self assembled monolayers by transition metal ion intercalation for enhancement of molecular junction conductivity.

This research delves into the role of metal ions in enhancing the electronic properties of 5,5'-bis(mercaptomethyl)-2,2'-bipyridine (BPD) self-assembled monolayers (SAMs). It combines experimental techniques and numerical simulations to understand the impact of these ions on the structural, electronic, and transport properties of BPD SAMs. Key findings include the varied bonding preferences of metal ions and their significant role in modifying the electronic structure of BPD molecules, leading to enhanced electron delocalization and migration. The study highlights the potential of metal ions in advancing molecular electronics, particularly in the development of high-performance electronic and energy devices.

Cardiac magnetic resonance findings in cardiac amyloidosis.

The purpose of this review is to highlight the increasing importance of cardiac magnetic resonance (CMR) imaging in diagnosing and managing cardiac amyloidosis, especially given the recent advancements in treatment options. This review emphasizes the crucial role of late gadolinium enhancement (LGE) with phase-sensitive inversion recovery (PSIR) techniques in both diagnosing and predicting patient outcomes in cardiac amyloidosis. The review also explores promising new techniques for diagnosing early-stage disease, such as native T1 mapping and ECV quantification. Additionally, it delves into experimental techniques like diffusion tensor imaging, MR elastography, and spectroscopy. This review underscores CMR as a powerful tool for diagnosing cardiac amyloidosis, assessing risk factors, and monitoring treatment response. While LGE imaging remains the current best practice for diagnosis, emerging techniques such as T1 mapping and ECV quantification offer promise for improved detection, particularly in early stages of the disease. This has significant implications for patient management as newer therapeutic options become available for cardiac amyloidosis.

Photophysical mechanism study of photophysical properties of new red BODIPY chromophores with or without methyl substitution

The relationship between the photophysical properties and structure of BODIPY derivatives always has attracted much attention. Two new BODIPY derivative chromophores with phenyl group substitutions at meso-/6- positions, with or without methyl substitutions at 1/3/5/7 positions were investigated by ways of combination of multiple experimental techniques and theoretical methods. The chromophore without methyl substitutions has a larger Stokes shift and better viscosity sensitivity compared to the other one. The intrinsic reason is that considerable charge transfer between the BODIPY core and the 6- position group is achieved in chromophore. However, this charge transfer process is severely weakened, if 1-/3-/5-/7- methyl substitutions existing, via restricting rotation between the core and side groups. At the same time, the non-radiative process is amplified significantly in chromophore without methyl substitution and the fluorescence efficiency decrease from 51.7% (with methyl substitutions) to 1.84% (without methyl substitutions) in DMSO. Quantum calculations indicate the presence or absence of methyl substitution can change both the shape and height of the torsional potential energy curve of the side groups, thereby affecting the fluorescence quantum yield and viscosity response performance of chromophores. Our work can provide foundation and ideas for designing and optimizing BODIPY derivatives with objective photophysical properties.

Fake views removal and popularity on YouTube

This paper analyses how YouTube authenticates engagement metrics and, more specifically, how the platform corrects view counts by removing “fake views” (i.e., views considered artificial or illegitimate by the platform). Working with one and a half years of data extracted from a thousand French YouTube channels, we show the massive extent of the corrections done by YouTube, which concern the large majority of the channels and over 78% of the videos in our corpus. Our analysis shows that corrections are not done continuously as videos collect new views, but instead occur in batches, generally around 5 p.m. every day. More significantly, most corrections occur relatively late in the life of the videos, after they have reached most of their audience, and the delay in correction is not independent of the final popularity of videos: videos corrected later in their life are more popular on average than those corrected earlier. We discuss the probable causes of this phenomenon and its possible negative consequences on content diffusion. By inflating view counts, fake views could make videos appear more popular than they are and unwarrantedly encourage their recommendation, thus potentially altering the public debate on the platform. This could have implications on the spread of online misinformation, but their in-depth exploration requires first-hand information on view corrections, which YouTube does not provide through its API. This paper presents a series of experimental techniques to work around this limitation, offering a practical contribution to the study of online attention cycles (as described in the “Data and methods” section). At the same time, this paper is also a call for greater transparency by YouTube and other online platforms about information with crucial implications for the quality of online debate.

Is the TCA cycle malate dehydrogenase-citrate synthase metabolon an illusion?

This review discusses the intriguing yet controversial concept of metabolons, focusing on the malate dehydrogenase-citrate synthase (MDH-CISY) metabolon as a model. Metabolons are multienzyme complexes composed of enzymes that catalyze sequential reactions in metabolic pathways. Metabolons have been proposed to enhance metabolic pathway efficiency by facilitating substrate channeling. However, there is skepticism about the presence of metabolons and their functionality in physiological conditions in vivo. We address the skepticism by reviewing compelling evidence supporting the existence of the MDH-CISY metabolon and highlighting its potential functions in cellular metabolism. The electrostatic interaction between MDH and CISY and the intermediate oxaloacetate, channeled within the metabolon, has been demonstrated using various experimental techniques, including protein-protein interaction assays, isotope dilution studies, and enzyme coupling assays. Regardless of the wealth of in vitro evidence, further validation is required to elucidate the functionality of MDH-CISY metabolons in living systems using advanced structural and spatial analysis techniques.

Multilayered Computational Framework for Designing Peptide Inhibitors of HVEM-LIGHT Interaction.

The herpesvirus entry mediator (HVEM) and its ligand LIGHT play crucial roles in immune system regulation, including T-cell proliferation, B-cell differentiation, and immunoglobulin secretion. However, excessive T-cell activation can lead to chronic inflammation and autoimmune diseases. Thus, inhibiting the HVEM-LIGHT interaction emerges as a promising therapeutic strategy for these conditions and in preventing adverse reactions in organ transplantation. This study focused on designing peptide inhibitors, targeting the HVEM-LIGHT interaction, using molecular dynamics (MD) simulations of 65 peptides derived from HVEM. These peptides varied in length and disulfide-bond configurations, crucial for their interaction with the LIGHT trimer. By simulating 31 HVEM domain variants, including the full-length protein, we assessed conformational changes upon LIGHT binding to understand the influence of HVEM segments and disulfide bonds on the binding mechanism. Employing multitrajectory microsecond-scale, all-atom MD simulations and molecular mechanics with generalized Born and surface area (MM-GBSA) binding energy estimation, we identified promising CRD2 domain variants with high LIGHT affinity. Notably, point mutations in these variants led to a peptide with a single disulfide bond (C58-C73) and a K54E substitution, exhibiting the highest binding affinity. The importance of the CRD2 domain and Cys58-Cys73 disulfide bond for interrupting HVEM-LIGHT interaction was further supported by analyzing truncated CRD2 variants, demonstrating similar binding strengths and mechanisms. Further investigations into the binding mechanism utilized steered MD simulations at various pulling speeds and umbrella sampling to estimate the energy profile of HVEM-based inhibitors with LIGHT. These comprehensive analyses revealed key interactions and different binding mechanisms, highlighting the increased binding affinity of selected peptide variants. Experimental circular dichroism techniques confirmed the structural properties of these variants. This study not only advances our understanding of the molecular basis of HVEM-LIGHT interactions but also provides a foundation for developing novel therapeutic strategies for immune-related disorders. Furthermore, it sets a gold standard for peptide inhibitor design in drug development due to its systematic approach.

APEAch: Automated Pipeline for End-to-End Analysis of Epigenomic and Transcriptomic Data.

With the advent of next-generation sequencing (NGS), experimental techniques that capture the biological significance of DNA loci or RNA molecules have emerged as fundamental tools for studying the epigenome and transcriptional regulation on a genome-wide scale. The volume of the generated data and the underlying complexity regarding their analysis highlight the need for robust and easy-to-use computational analytic methods that can streamline the process and provide valuable biological insights. Our solution, aPEAch, is an automated pipeline that facilitates the end-to-end analysis of both DNA- and RNA-sequencing assays, including small RNA sequencing, from assessing the quality of the input sample files to answering meaningful biological questions by exploiting the rich information embedded in biological data. Our method is implemented in Python, based on a modular approach that enables users to choose the path and extent of the analysis and the representations of the results. The pipeline can process samples with single or multiple replicates in batches, allowing the ease of use and reproducibility of the analysis across all samples. aPEAch provides a variety of sample metrics such as quality control reports, fragment size distribution plots, and all intermediate output files, enabling the pipeline to be re-executed with different parameters or algorithms, along with the publication-ready visualization of the results. Furthermore, aPEAch seamlessly incorporates advanced unsupervised learning analyses by automating clustering optimization and visualization, thus providing invaluable insight into the underlying biological mechanisms.

Wind Tunnel Tests of a Thick Wind Turbine Airfoil

ABSTRACTThis article reports about a wind‐tunnel experiment carried out in the ONERA F2 low‐speed wind tunnel on a model of the DU 97‐W‐300Mod airfoil designed for wind turbine application. The wind tunnel, the airfoil model, and experimental techniques used are presented, with special emphasis on the data processing and corrections required to derive airfoil forces and pressure distribution. To better document the flow physics at play, the results are illustrated by infrared thermography and surface oil flow visualization. The test allowed investigating Reynolds number effects between 1 and 3.8 millions. To ameliorate the understanding of the benefits and limitations of such airfoil testing, one section is devoted to the comparison of present results with previous experiments in other wind tunnels. Some of the difficulties arising in airfoil testing are evidenced and discussed to contribute to the improvement of test methods.

تأثير استخدام طريقة السماع و المحافظة على استيعاب المفردات في الفصلالسابع المتوسطة بالمدرسة الإسلامية أولو النهى ميدان جوهور

The formulation of the problem in this research is, (1) what is the ability of first grade students at Ulun Nuha Islamic Middle School in Medan to master mufrodath using imitation and memorization methods, (2) what is the ability of first grade students at Ulun Nuha Islamic Middle School in Medan to master mufrodath without using the method imitating and memorizing, (3) what is the influence of the use of imitating and memorizing methods on the mastery of mufrodath in the first grade of Ulun Nuha Islamic Middle School, Medan. The research method used is quantitative research in the form of an experimental research method and data analysis techniques using statistics with a True Experimental research design with a posttest-only control design. And the female students' scores have been obtained: (1) By using the method of imitating and memorizing the mastery of mufrodath in the experimental class using the formula with the achievement "Jayyid" with an average score of 79.9, (2) Meanwhile the level of ability of female students without using the method of imitating and memorizing mastery of mufrodath in the control class using a formula with the achievement "Jayyid Murtafi'" with an average score of 51.8, (3) Then there is the influence of using imitation and memorization methods on mastery of mufrodath by referring to the value of the t-test using the formula, namely the value t0 is greater than the tt value, 9.52 > 2.76. And this explanation shows that the alternative hypothesis is accepted. So it can be concluded that there is an influence of the use of imitation and memorization methods on mastery of mufrodat.

Photochemical Initiation and Reactions of Thiyl Radicals Studied with SH2' Radical Traps.

A radical trapping method based on an SH2' homolytic substitution reaction was applied to study the mechanism of a photochemical spirocyclisation of indole-ynones in the presence of thiols. Starting material, products and a range of trapped radical intermediates were simultaneously detected in reaction mixtures by mass spectrometry (MS). The trapped intermediates included both initiating and main chain propagating radicals. These data made it possible to propose a self-initiation mechanism consistent with the originally postulated photoexcitation of an intramolecular electron donor-acceptor complex of the substrate. The effect of thiol structure on the MS peak intensity of the reaction components was rationalised in terms of the relative stability of the radical intermediates. The results were compared to a simpler related reaction, a photochemical thiol-ene addition where reagents, products and trapped intermediate radicals were also detected by MS. Relative MS peak intensities were again explained by a combination of electronic and steric effects on the stability of intermediate radicals. Overall, SH2' radical trapping was demonstrated to be a powerful experimental technique for providing mechanistic evidence on photochemical and other organic radical reactions.

On Experimental Determination of Poisson’s Ratio for Rock-like Materials using Digital Image Correlation

This article compares the two most used strain determination experimental techniques, the strain gauges and the digital image correlation (DIC), which are used here to determine the static Poisson's ratio of rock-like materials under a compressive loading. While the strain gauge technique measures the strains on the small patch of the underlying material on the spot, where the strain gauge is applied, DIC is a novel optical full-field technique that can measure the strains over the entire region of interest of the specimen. The key research question presented in this paper and research significance is to what extent the measurement of Poisson’s ratio is improved by leveraging the richness of the full-field measurements compared to the conventional strain gauge technique. To this purpose, the hypothesis was tested through virtual experiments in which a numerical simulation of a uniaxial compression test with a cylindrical, rock-like sample was created to mimic the strain gauge and DIC measurement techniques, as well as by conducting an actual compression test on a sandstone material. In contrast to conventional strain gauges, novel optical techniques such as stereo DIC proved to be able to capture the macroscopic Poisson coefficient with higher precision, thus reducing the margin of error.

Unsupervised modeling of mutational landscapes of adeno-associated viruses viability

Adeno-associated viruses 2 (AAV2) are minute viruses renowned for their capacity to infect human cells and akin organisms. They have recently emerged as prominent candidates in the field of gene therapy, primarily attributed to their inherent non-pathogenic nature in humans and the safety associated with their manipulation. The efficacy of AAV2 as gene therapy vectors hinges on their ability to infiltrate host cells, a phenomenon reliant on their competence to construct a capsid capable of breaching the nucleus of the target cell. To enhance their infection potential, researchers have extensively scrutinized various combinatorial libraries by introducing mutations into the capsid, aiming to boost their effectiveness. The emergence of high-throughput experimental techniques, like deep mutational scanning (DMS), has made it feasible to experimentally assess the fitness of these libraries for their intended purpose. Notably, machine learning is starting to demonstrate its potential in addressing predictions within the mutational landscape from sequence data. In this context, we introduce a biophysically-inspired model designed to predict the viability of genetic variants in DMS experiments. This model is tailored to a specific segment of the CAP region within AAV2’s capsid protein. To evaluate its effectiveness, we conduct model training with diverse datasets, each tailored to explore different aspects of the mutational landscape influenced by the selection process. Our assessment of the biophysical model centers on two primary objectives: (i) providing quantitative forecasts for the log-selectivity of variants and (ii) deploying it as a binary classifier to categorize sequences into viable and non-viable classes.

Scleral collagen crosslinking as a promising direction of sclera-strengthening treatment of progressive myopia

The review presents recent research works on new technologies of scleral collagen crosslinking, a promising approach to sclerastrengthening treatment of progressive myopia. We assess the advantages and limitations of a number of experimental techniques of photochemical and medicinal crosslinking of the sclera, as well as donor tissue crosslinking aimed at optimizing the plastic material for sclera-strengthening surgery. Successful experiments and effective first clinical implementation results of the approach can be viewed as the basis for its further improvement and wider introduction of the technology into ophthalmological practice.

Impact of CuO on physical, structural and optical properties of sodium-phosphate glasses

The present work is involved in the synthesize, characterization and evaluating the role of CuO on physical, structural and optical properties of 45P2O5-(55-x)Na2O-xCuO (x=0, 1.0, 3.0 and 5.0 mol%) compositions. The as-synthesized samples are characterized by various experimental techniques such as XRD, FTIR, Raman and UV visible spectroscopy to study their suitability for laser and non-linear optical applications. The density of glasses increases whereas molar volume decreases from with the doping of CuO in place of Na2O. The amorphous nature of the prepared samples is confirmed by X-ray pattern. FTIR and Raman spectra confirm the presence of metaphosphate (Q2) and orthophosphate (Q0) structural units in the prepared glass samples which confirms that the glass network become more polymerised with the addition of CuO in place of Na2O. The optical band gap increases from 1.94 to 4.11 eV whereas refractive index decreases from 2.76 to 2.14 with increasing doping of CuO. The molar refraction decreases while metallization criteria increase with CuO doping. This glass material demonstrates promising potential for applications in non-linear optics.

Shaping Closed-Loop supply chain Dynamics: Mitigating the bullwhip effect and improving customer satisfactionin production systems with material reuse

Modern societies are currently transitioning towards more circular economic models to reduce environmental impacts and leverage economic opportunities. Managing the emerging supply chains, more complex and uncertain, poses a considerable challenge for many organisations. This work examines the dynamic behaviour of these closed-loop systems under different replenishment policies and varying levels of product returns and lead times. We model a generalised multi-level, closed-loop supply chain of a production system with material reuse, drawing inspiration from the real-world operations of cider makers in Spain. We investigate its ability to effectively and efficiently satisfy the consumer through four performance metrics: fill rate, bullwhip ratio, inventory cover, and reuse demand share. Through experimentation techniques, we observe that the highest performance is generally obtained when the retailer applies a pure pull policy while the manufacturer adopts a level scheduling policy. This strategy, built on lean principles, can achieve much lower operational costs while providing similar, or even better, service levels compared to more popular and complex alternatives. Based on our findings, we provide a set of actionable managerial implications that would help supply chain professionals successfully implement and manage these supply chains.