Physical Basis Research Articles

Theoretical model of the temperature-dependent ultimate tensile strength from the viewpoint of dislocation kinetics approach for FCC metals

In this work, based on the force-heat equivalence energy density principle and the theory of dislocation kinetics, a dislocation-based theoretical model of temperature-dependent ultimate tensile strength without fitting parameters is developed. The novelty of this model is that the theoretical characterization of the temperature-dependent dislocation annihilation energy barrier is implemented, and the new temperature-dependent expressions of the dislocation annihilation term and the dislocation storage term in the dislocation kinetics approach are derived. The model is well validated by comparing against available experimental results of pure face-centered cubic metals in a wide temperature range with the lowest temperature close to absolute temperature 0 K and the highest temperature close to melting point. Furthermore, the analysis results of the model show that increasing the dislocation storage coefficient and reducing the dislocation annihilation coefficient are effective measures to improve the ultimate tensile strength of metal materials, particularly at lower temperatures. The theoretical model provides a clear and profound physical basis for understanding the evolution of ultimate tensile strength at different temperatures.

Study on the mechanical properties and energy dissipation characteristics of concrete subjected to high strain rate and sulfate attack

Marine structures, such as cross-sea bridges, port constructions, and offshore drilling platforms, are not only subjected to sulfate erosion, but also to various dynamic loads. Analyzing the damage evolution process of concrete under sulfate erosion and impact loads is the key to improving the lifespan of concrete. In order to study the damage evolution process of eroded concrete under high strain rates, the energy dissipation characteristics, basic physics and mechanical properties, and micro-fracture mechanism of sulfate-eroded concrete at different sulfate concentrations (C=0, 3%, 6%, and 9%) under high strain rate ranging from 70/s to 85/s are systematically studied by using the split Hopkinson pressure bar (SHPB) test system, X-ray diffractometer and SEM scanning electron microscope. The research results indicate that an increase in sulfate concentration leads to a decrease in Ca(OH)2 content and an increase in Ettringite (AFt) content in concrete specimens; As the sulfate concentration increases, the dynamic peak strength and dynamic elastic modulus of concrete specimens gradually decrease, while the dynamic peak strain of concrete specimens gradually increases; The degree of macroscopic fragmentation in concrete specimens subjected to impact compression becomes increasingly severe with rising sulfate concentrations; As the sulfate concentration increases, the proportion of reflected energy and dissipated energy gradually increases, while that of transmitted energy gradually decreases, and the energy absorption capacity of the sample is significantly improved; The results of the SEM test shows that with the increase of sulfate concentration, a large amount of AFt is generated at the joint fissures and the interface of cement aggregates, the expansion of AFt and the crack development of concrete reduce the integrity and stability of concrete. This study holds significant guidance for the application of concrete in impact situations under a sulfate attack environment.

Multi-year hyperspectral remote sensing of a comprehensive set of crop foliar nutrients in cranberries

Hyperspectral remote sensing has emerged as an efficient tool to quantify the spatial and temporal variations in crop foliar nutrients, thus reducing the burden on in-situ tissue sampling and traditional chemical assays. However, the physical mechanism of hyperspectral remote sensing of foliar nutrients is under-explored, especially for those lacking absorption features. Using four-year data collected from a cranberry farm, we demonstrate the capacity of leaf and imaging spectroscopy to quantify a comprehensive set of crop foliar nutrients, including seven macronutrients (N, P, K, Mg, Ca, S, Na) and five micronutrients (Fe, Mn, B, Cu, Zn). Specifically, we: 1) compared the performance of four data-driven approaches to estimate foliar nutrients at both leaf and canopy scales, including partial least square regression (PLSR), support vector regression (SVR), Gaussian process regression (GPR) and random forest regression (RFR); and 2) explored the physical basis of hyperspectral remote sensing of foliar nutrients. Our results showed that: 1) at leaf scales linear approaches PLSR and SVR performed best for nine nutrients (P, Mg, Ca, S, Na, Fe, B, Cu and Zn), whereas nonlinear approaches GPR and RFR performed best only for three nutrients (N, K and Mn); 2) at canopy scales no data-driven approach significantly outperformed others; 3) the best modelling accuracy varied with foliar nutrients (leaf scales: R2 from 0.30 to 0.93 and RRMSE from 9 to 51%; canopy scales: R2 from 0.15 to 0.81 and RRMSE from 7 to 37%). The physical basis of hyperspectral remote sensing of foliar nutrients was mainly attributed to their strong correlations with leaf compounds that have apparent absorption features. More specifically, at leaf scales the correlation between foliar nutrients and LMA (leaf mass per area) was leveraged by models to predict foliar nutrients from leaf spectra; at canopy scales the correlation of foliar nutrients with leaf chlorophyll and canopy LAI (Leaf area index) was leveraged by models to predict foliar nutrients from canopy spectra. This study revealed the importance of trait correlations in predicting foliar nutrients, and improved our understanding of the physical mechanisms in hyperspectral remotes sensing of foliar nutrients.

Student Responses to Video Media Tutorial Basic Physics Practicum on Series and Parallel Circuits Material

This research aims to determine student responses to the development of basic physics practical video tutorial media on series and parallel circuits. This research is quantitative descriptive research. The samples used in this research were twenty-five students from the physics education study program in the odd semester of the academic year: 2022/2023 at one of the universities in Sumba who took Basic Physics courses. Data collection in this research used a questionnaire containing statements using a Likert scale. The data obtained is analyzed for each indicator in the questionnaire, then the percentage score obtained will be calculated. Based on the results of data analysis, it was found that the student response to the basic physics practical video tutorial media on series and parallel circuit material was very positive (91.3%) meaning that the use of practical video tutorial media in basic physics practicum activities on series and parallel circuit material received a response good thing from students. The percentage of each aspect measured obtained the following values: (1) the attractiveness of the practical tutorial video media was 92% (very positive category); (2) ease of use of practical video tutorial media by 94% (very positive category); and (3) the role of practical video tutorial media in series and parallel series practicum was 88% (very positive category). The results obtained show that the practical video tutorial media is highly accepted by students as a medium that can assist in basic physics practical activities, especially in series and parallel circuit material. The implication of the results of this research is that it is easier for students to understand the steps when carrying out practicum activities because there are practicum video tutorials that help students learn material related to the practicum that will be carried out, especially for practicum material regarding series and parallel circuits.

FUNDAMENTALS OF SCALING OF OVERALL COOLING EFFECTIVENESS WITH TEMPERATURE RATIO

Abstract In this paper we study the relationship between overall cooling effectiveness (or so-called metal effectiveness) and mainstream-to-coolant total temperature ratio (TR), for typical high-pressure nozzle guide vane (HPNGV) cooling systems. The temperature ratio range studied is that between typical experimental conditions (TR ≅ 1.2) and typical engine conditions (TR ≅ 2.0). The purpose is twofold: firstly, to quantify the difference in overall cooling effectiveness between experimental and engine conditions of temperature ratio; and—secondly—to understand the physical bases for the difference, separated in terms of changes in five local surface boundary conditions. We do this using a bespoke conjugate thermal model which includes models of both the internal cooling and the external film cooling layer. Three typical cooling architectures are studied. The results allow comparison and scaling between situations at different conditions of temperature ratio.

Real-time observation of magnetization and magnon dynamics in a two-dimensional topological antiferromagnet MnBi2Te4

Atomically thin van der Waals magnetic materials have not only provided a fertile playground to explore basic physics in the two-dimensional (2D) limit but also created vast opportunities for novel ultrafast functional devices. Here we systematically investigate ultrafast magnetization dynamics and spin wave dynamics in few-layer topological antiferromagnetic MnBi2Te4 crystals as a function of layer number, temperature, and magnetic field. We find laser-induced (de)magnetization processes can be used to accurately track the distinct magnetic states in different magnetic field regimes, including showing clear odd–even layer number effects. In addition, strongly field-dependent AFM magnon modes with tens of gigahertz frequencies are optically generated and directly observed in the time domain. Remarkably, we find that magnetization and magnon dynamics can be observed in not only the time-resolved magneto-optical Kerr effect but also the time resolved reflectivity, indicating strong correlation between the magnetic state and electronic structure. These measurements present the first comprehensive overview of ultrafast spin dynamics in this novel 2D antiferromagnet, paving the way for potential applications in 2D antiferromagnetic spintronics and magnonics as well as further studies of ultrafast control of both magnetization and topological quantum states.

Analysis of Momentum and Impulse Misconceptions of College Students Using Four-Tier Diagnostic Tests

This research aims to discover misconceptions about momentum and impulse concepts. The research method used in this research is a mixed method. The subjects of this research were students majoring in physics from the classes of 2019, 2020, and 2021 who had taken the basic physics course I, with a total sample of 44 students. The instrument used was 15 four-level multiple diagnostic tests. Research data was obtained based on student answer patterns on a four-level multiple-choice test. The results of the research show that students' conceptual understanding of momentum and impulse material using the four-level diagnostic test is still relatively low, as seen from the percentage of students who partially understand the concept at 46%, understand the concept at 30%, negative misconceptions at 10%, positive misconceptions at 9%, and positive misconceptions at 5%. Some of the misconceptions experienced by students regarding the concepts of momentum and impulse include: first, students assume that only mass influences the amount of momentum; second, they assume that the total momentum of a system of isolated objects is not constant; third, assume that the total momentum of a system of isolated objects is not constant, the fourth assumes that two objects of the same mass have different speeds, the sixth assumes that changes in the speed of a particle are only influenced by force and time and the last, namely the seventh, assumes that the process of collisions on smooth surfaces will move all objects.

RETRACTED: Modeling a unified slug liquid holdup correlation based on a comprehensive analysis of entering bubble sharpness

Liquid-gas two-phase slug flow is the most complex flow pattern encountered in pipelines, wellbores, and cooling systems in various energy systems. Accurately predicting the slug liquid holdup (HLLS) is vital for the system design and operation because it is a crucial characteristic of slug flow that is closely related to the average liquid holdup and pressure drop. Most existing HLLS models have limited applicability due to a lack of a physical basis for slug aeration mechanisms. This study proposes a new dimensionless number SP to estimate the sharpness of entering bubbles at the liquid slug front and semi-empirically correlates SP to HLLS data, leading to the development of a unified HLLS correlation. We formulate this dimensionless number and its relations using 880 experimental HLLS data points, and the validity of the unified HLLS correlation is tested using 1050 independent data points. The developed semi-empirical model closely agrees with experimental data obtained by varying the fluid properties (0.03 mPa·s ≤ µL ≤ 966 mPa·s, 0.027 N/m ≤ σ ≤ 0.07 N/m) and operating conditions, such as the pipe geometry (1 in. ≤ pipe internal diameter ≤ 3 in., –10° ≤ θ ≤ +90°).

Domestic cat larynges can produce purring frequencies without neural input

Most mammals produce vocal sounds according to the myoelastic-aerodynamic (MEAD) principle, through self-sustaining oscillation of laryngeal tissues.1,2 In contrast, cats have long been believed to produce their low-frequency purr vocalizations through a radically different mechanism involving active muscle contractions (AMC), where neurally driven electromyographic burst patterns (typically at 20-30Hz) cause the intrinsic laryngeal muscles to actively modulate the respiratory airflow. Direct empirical evidence for this AMC mechanism is sparse.3 Here, the fundamental frequency (fo) ranges of eight domestic cats (Felis silvestris catus) were investigated in an excised larynx setup, to test the prediction of the AMC hypothesis that vibration should be impossible without neuromuscular activity, and thus unattainable in excised larynx setups, which are based on MEAD principles. Surprisingly, all eight excised larynges produced self-sustained oscillations at typical cat purring rates. Histological analysis of cat larynges revealed the presence of connective tissue masses, up to 4mm in diameter, embedded in the vocal fold.4 This vocal fold specialization appears to allow the unusually low fo values observed in purring. While our data do not fully reject the AMC hypothesis for purring, they show that cat larynges can easily produce sounds in the purr regime with fundamental frequencies of 25 to 30Hz without neural input or muscular contraction. This strongly suggests that the physical and physiological basis of cat purring involves the same MEAD-based mechanisms as other cat vocalizations (e.g., meows) and most other vertebrate vocalizations but is potentially augmented by AMC.

The physical basis of osmosis.

Osmosis is an important force in all living organisms, yet the molecular basis of osmosis is widely misunderstood as arising from diffusion of water across a membrane separating solutions of differing osmolarities, and hence different water concentrations. In 1923, Peter Debye proposed a physical model for a semipermeable membrane emphasizing the repulsive forces between solute molecules and membrane that prevent the solute from entering the membrane. His work was hardly noticed at the time and slipped out of view. We show that Debye's analysis of van 't Hoff's law for osmotic equilibrium also provides a consistent and plausible mechanism for osmotic flow. A difference in osmolyte concentrations in solutions separated by a semipermeable membrane leads to different pressures at the two water-membrane interfaces because the total repulsive force between solute molecules and the membrane is different at the two interfaces. Water is therefore driven through the membrane for exactly the same reason that pure water flows in response to an imposed hydrostatic pressure difference. In this paper, we present the Debye model in both equilibrium and flow conditions. We point out its applicability regardless of the nature of the membrane with examples ranging from the predominantly convective flow of water through synthetic membranes and capillary walls to the purely diffusive flow of independent water molecules through a lipid bilayer and the flow of a single-file column of water molecules in narrow protein channels.

Improved yellowness index (YI) control in ABS compounding process through virtual control using an RNN-based neural network soft-sensor model

Soft sensors have gained widespread acceptance due to their ability to handle highly complex systems. However, their application in process control remains limited, primarily due to the lack of interpretability associated with most soft sensors, which are often black-box models without a clear physical basis. In an effort to address this issue, this study proposes a novel approach to soft-sensor construction by integrating the eXtreme Gradient Boosting (XGBoost) technique with the Gated Recurrent Unit (GRU) in chemical engineering. The approach is applied to a real-world industrial ABS (Acrylonitrile-Butadiene-Styrene) resin compounding process. After the predictive performance and physical correctness of the soft sensor are validated, a virtual fuzzy control system is constructed using data from the soft-sensor prediction. The results show that the proposed method with superior predictive performance and physical correctness, and its use in the control system improves the stability of the product quality and decreases grade transition times.

Measurement of Specific Heat of Organic Materials Using Non-Isolating Container and Arduino

<p>This study reports a novel method for specific heat measurements of organic materials namely potaoes, quinces and radishes. The method proposed in this work is novel in the sense that it employs a non-isolated container and an Arduino microprocessors. The actual measurements are simply managed by placing the organic materials within hot water in a non-isolating container and by monitoring the temperature and time by means of Arduino UNO microprocessor. The heat leakage due to the non-isolated container is determined by using the heat versus time graph of the system and by mathematically modeling the temperature decrease by the time due to the heat exchange between the hot water and the environment. The measurements have revealed that the relative errors for the measurements are approximately % 4.75 for potatoes, % 21.50 for radishes and % 1.30 for quinces. The approach described in this work is inexpensive, very easy to apply and can potentially be beneficial for basic physics, science and engineering research activities.</p>

High-Temperature Compression Behaviors and Constitutive Models of a 7046-Aluminum Alloy.

High-temperature forming behaviors of a 7046-aluminum alloy were investigated by hot compression experiments. The microstructural evolution features with the changes in deformation parameters were dissected. Results indicated the formation of massive dislocation clusters/cells and subgrains through the intense DRV mechanism at low compression temperature. With an increase in deformation temperature, the annihilation of dislocations and the coarsening of subgrains/DRX grains became prominent, due to the collaborative effects of the DRV and DRX mechanisms. However, the growth of subgrains and DRX grains displayed the weakening trend at high strain rates. Moreover, two constitutive models involving a physically based (PB) model and a gate recurrent unit (GRU) model were proposed for predicting the hot compression features. By validation analysis, the predicted values of true stress perfectly fit with the experimental data, indicating that both the proposed PB model and the GRU model can accurately predict the hot compression behaviors of 7046-aluminum alloys.

Origin and Mechanism of Piezoelectric and Photovoltaic Effects in (111) Polar Orientated NiO Films.

Based on the current piezoelectric theory, NiO with the centrosymmetric structure is not piezoelectric. However, herein, this study shows the first observation of piezoelectric generation, rectifyingand bulk photovoltaic behaviors in NiO films with [111] orientation and the change in NiO crystal structure in piezoelectric process. The piezoelectric generation, rectifying, and bulk photovoltaic performances are enhanced by increasing (111) orientation, and attenuated and eliminated by applying a persistent stress on the NiO film. The NiO [111] is polar direction, and thus a spontaneous electric field (ES ) is in the NiO film with [111] orientation. The existence of Es in (111) oriented NiO film is found to be the physical basis of the piezoelectric generators and photovoltaic and rectifying effects. Thus, NiO piezoelectric, rectifying, and bulk photovoltaic mechanism are presented at the atomic level. The mechanism may rewrite the current piezoelectric theory, and establish a unified theory of polar structure with wide implications. The polar-orientated films can be used to fabricate piezoelectric generators and other optoelectronic devices with high performances.

Impact of Basic Physics E-Module Using Problem Oriented on Critical Thinking Skilss of Physics Teacher Candidate Student

The aim of this work was to investigate the effect of problem-oriented basic physics modules on improving the critical thinking skills of physics teacher candidate students. The type of research used was semi-experimental in two different classes. The next target of this research was the students of Samudra University's FKIP Physics Graduate Program. The data collection tools and techniques used in this study are basic physics questions that enhance critical thinking through problem-based basic physic e-modules. The results of this study, namely the hypothesis test results, were obtained sig (2-tailed) = 0.000 < 0.05, when testing the hypothesis that H0 is rejected and Ha is accepted. Therefore, it can be concluded that the e-module of basic physics has a problem-based effect on the critical thinking skills of physics teacher candidate students. Effect size value is d = 2.90 > 0.08, so it can be considered high. Therefore, it can be concluded that there is an influence of the electronic module of basic physics using a problem-oriented approach on the critical thinking skills of prospective physics teacher students. This research shows how effective E-modules are in fostering critical thinking abilities.

SmeftFR v3 – Feynman rules generator for the Standard Model Effective Field Theory

We present version 3 of SmeftFR, a Mathematica package designed to generate the Feynman rules for the Standard Model Effective Field Theory (SMEFT) including the complete set of gauge invariant operators up to dimension-6 and the complete set of bosonic operators of dimension-8. Feynman rules are generated with the use of FeynRules package, directly in the physical (mass eigenstates) basis for all fields. The complete set of interaction vertices can be derived, including all or any chosen subset of SMEFT operators. As an option, the user can also choose preferred gauge fixing, generating Feynman rules in unitary or Rξ-gauges. The novel feature in version-3 of SmeftFR is its ability to calculate SMEFT interactions consistently up to dimension-8 in EFT expansion (including quadratic dimension-6 terms) and express the vertices directly in terms of user-defined set of input-parameters. The derived Lagrangian in the mass basis can be exported in various formats supported by FeynRules, such as UFO, FeynArts, etc. Initialisation of numerical values of Wilson coefficients of higher dimension operators is interfaced to WCxf format. The package also includes a dedicated Latex generator allowing to print the result in clear human-readable form. The SmeftFR v3 is publicly available at http://www.fuw.edu.pl/smeft. Program summaryProgram Title:SmeftFR v3.0CPC Library link to program files:https://doi.org/10.17632/h4787mfvfz.1Licensing provisions: GPLv3Programming language: Mathematica 12.1 or later (earlier versions were reported to have problems running this code)External routines/libraries: Wolfram Mathematica programSubprograms used:FeynRules v2.3.49 or later packageNature of problem: Automatised generation of Feynman rules in physical (mass) basis for the Standard Model Effective Field Theory with user defined operator subset, gauge fixing and input-parameters scheme selection.Solution method: Expansion of SmeftFR v2 Mathematica package [1]: implementation of the results of Ref. [2] in the FeynRules package [3], including dynamic “model files” generation.

Multirepresentation-Based Physics E-Module Development

This research is a research and development with the final result of developing a multi-representation-based Physics E-Module. The development of the Physics E-Module aims to produce innovations in teaching materials that can be applied to the learning process and to support independent or student-centred learning. The Physics E-Module was developed on a multi-representational basis. Multirepresentation aims for students to get various representations of a material. The development research method used is the ADDIE design development method. This method was chosen because it is one of the basic development methods and is easy to implement. The ADDIE design development stages include Analyze, Development, Implementation, and Evaluate. The product feasibility test was carried out by involving 16 Tadris IPA Biologi UIN Mataram students. The Flip PDF Corporate supports the appearance of the multi-representation-based Physics E-Module so that the appearance of the Physics E-Module has an effect like opening a printed book. The multi-representation used in the Physics E-Module is verbal, graphic image, and audio-visual representations. Expert validators in the media and material carry out the feasibility test. The feasibility test results in the media sector are 90%, with a very feasible category. The feasibility test results in the material sector are 94.6%, with a very feasible category. The scores of the student's responses to the development of multi-representation-based Physics E-Modules range from 3.5 to 4, with a maximum score of 4. The results of this study have implications for the provision of valid and feasible Basic Physics teaching material for use in learning, especially online learning.

The C-terminus of α-Synuclein regulates its dynamic cellular internalization by Neurexin 1β.

The aggregation of the disordered neuronal protein, α-Synuclein (αS), is the primary pathological feature of Parkinson's disease. Current hypotheses favor cell-to-cell spread of αS species as underlying disease progression, driving interest in identifying the molecular species and cellular processes involved in cellular internalization of αS. Prior work from our lab identified the chemically specific interaction between αS and the pre-synaptic adhesion protein neurexin 1β (N1β) to be capable of driving cellular internalization of both monomer and aggregated forms of αS. Here we explore the physical basis of N1β-driven internalization of αS. Specifically, we show that spontaneous internalization of αS by SH-SY5Y and HEK293 cells expressing N1β requires essentially all of the membrane-binding domain of αS; αS constructs truncated beyond residue 90 bind to N1β in the plasma membrane of HEK cells, but are not internalized. Interestingly, prior to internalization, αS and N1β co-diffuse rapidly in the plasma membrane. αS constructs that are not internalized show very slow mobility themselves, as well as slow N1β diffusion. Finally, we find that truncated αS is capable of blocking internalization of full-length αS. Our results draw attention to the potential therapeutic value of blocking αS-N1β interactions.

Physics basis for the Wisconsin HTS Axisymmetric Mirror (WHAM)

The Wisconsin high-temperature superconductor axisymmetric mirror experiment (WHAM) will be a high-field platform for prototyping technologies, validating interchange stabilization techniques and benchmarking numerical code performance, enabling the next step up to reactor parameters. A detailed overview of the experimental apparatus and its various subsystems is presented. WHAM will use electron cyclotron heating to ionize and build a dense target plasma for neutral beam injection of fast ions, stabilized by edge-biased sheared flow. At 25 keV injection energies, charge exchange dominates over impact ionization and limits the effectiveness of neutral beam injection fuelling. This paper outlines an iterative technique for self-consistently predicting the neutral beam driven anisotropic ion distribution and its role in the finite beta equilibrium. Beginning with recent work by Egedalet al.(Nucl. Fusion, vol. 62, no. 12, 2022, p. 126053) on the WHAM geometry, we detail how the FIDASIM code is used to model the charge exchange sources and sinks in the distribution function, and both are combined with an anisotropic magnetohydrodynamic equilibrium solver method to self-consistently reach an equilibrium. We compare this with recent results using the CQL3D code adapted for the mirror geometry, which includes the high-harmonic fast wave heating of fast ions.

Stress granule-mediated RNA regulatory mechanism in Alzheimer's disease.

Living organisms experience a range of stresses. To cope effectively with these stresses, eukaryotic cells have evolved a sophisticated mechanism involving the formation of stress granules (SGs), which play a crucial role in protecting various types of RNA species under stress, such as mRNAs and long non-coding RNAs (lncRNAs). SGs are non-membranous cytoplasmic ribonucleoprotein (RNP) granules, and the RNAs they contain are translationally stalled. Importantly, SGs have been thought to contribute to the pathophysiology of neurodegenerative diseases, including Alzheimer's disease (AD). SGs also contain multiple RNA-binding proteins (RBPs), several of which have been implicated in AD progression. SGs are transient structures that dissipate after stress relief. However, the chronic stresses associated with aging lead to the persistent formation of SGs and subsequently to solid-like pathological SGs, which could impair cellular RNA metabolism and also act as a nidus for the aberrant aggregation of AD-associated proteins. In this paper, we provide a comprehensive summary of the physical basis of SG-enriched RNAs and SG-resident RBPs. We then review the characteristics of AD-associated gene transcripts and their similarity to the SG-enriched RNAs. Furthermore, we summarize and discuss the functional implications of SGs in neuronal RNA metabolism and the aberrant aggregation of AD-associated proteins mediated by SG-resident RBPs in the context of AD pathogenesis. Geriatr Gerontol Int 2024; 24: 7-14.