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Coarse-graining of fluids is challenging because fluid particles are unbound and diffuse long distances in time. One approach creates coarse-grain variables that group all particles within a region centered on specific points in space and accounts for the movement of particles among such regions. In our previous work, we showed that in many cases, potential interactions for such a scheme adopted a generalized quadratic form, whose parameters depend on means, variances, and correlation coefficients among the coarse-grain variables. In this work, we use statistical mechanics to derive analytic expressions for these parameters, using properties of the fluid, including pair distribution functions. These expressions are compared against simulation-derived values and shown to be in good agreement. This approach can be used to calculate a priori the potential for any homogeneous, simple fluid, without the need for fitting procedures or matching, thus increasing the ease of use of this coarse-grain scheme and creating a foundation for large-scale bottom-up simulations. Furthermore, these expressions provide a quantitative way of studying the boundary between discrete (atomic) and continuum models of fluids. [ABSTRACT FROM AUTHOR]

The New Austrian Tunneling Method (NATM) essentially rests on observational information concerning displacements measured in selected positions at the inner surface of shotcrete tunnel shells. The combination of these measurements with advanced material and structural mechanics, in the course of so-called hybrid methods, have successfully delivered, for more than 20 years, practically relevant estimations of internal and external forces and corresponding degrees of utilization. The reliability of the latter, however, may crucially depend on the used material model. Based on a recently proposed analytical structural mechanics model [Acta Mech 233, 2989–3019 (2022)], and focusing on the benchmark example of measurement cross section MC1452 of the Sieberg tunnel, driven in the 1990s in Miocene clay marl, the present paper compares the estimations of forces and degrees of utilization arising from differently refined constitutive concepts, namely (i) aging elasticity, (ii) aging linear viscoelasticity, and (iii) aging nonlinear viscoelasticity. It turns out that only the consideration of aging nonlinear viscoelastic material behavior provides access to realistic values for the degree of utilization, being lower than one. Simpler material models would indicate local material failure, which was not observed in situ. [ABSTRACT FROM AUTHOR]

Definition: This entry first provides an overview of the historical, cultural and epistemological background that is key for Hamilton's positions on mechanics. We consider the investigations on geometrical optics in the 17th and 18th centuries, Euler's and Lagrange's foundations of variational calculus in the 18th century to find extrema of physical quantities expressed as infinite sums of infinitesimals (today, we would say 'definite integrals'), and Lagrange's introduction of a revolutionary analytical mechanics, all of which are all fertile grounds for Hamilton's steps—first, in what we could call analytical optics, then in an advanced form of analytical mechanics. Having provided such an overview, we run through some of Hamilton's original papers to highlight how he posed his principle(s) in the wake of his forerunners and how his principles are linked with the search for a unitary view of physics. [ABSTRACT FROM AUTHOR]

We analyse the stability of the de Sitter equilibria in multi-resonant planetary systems. The de Sitter equilibrium is the dynamical state of the Laplace resonance in which all resonant arguments are librating. The sequence of equilibria exists all along the possible states balancing resonance offsets and forced eccentricities. Possible additional new de Sitter equilibria may exist when at least one of the forced eccentricities is large (the paradigmatic case is Gliese 876). In the present work, these families of equilibria are traced up to crossing exact commensurability, where approximate first-order solutions diverge. Explicit exact location of the equilibria is determined allowing us to verify the Lyapunov stability of the standard de Sitter equilibrium and of the stable branches of the additional ones. [ABSTRACT FROM AUTHOR]

We follow the Boltzmann-Clausius-Maxwell (BCM) proposal to establish the generalized second law (GSL) that is applicable to a system of any size, including a single particle system as our example establishes, and that supercedes the celebrated second law (SL) of increase of entropy of an isolated system. It is merely a consequence of the mechanical equilibrium (stable or unstable) principle (Mec-EQ-P) of analytical mechanics and the first law. We justify an irreversibility priciple that covers all processes, spontaneous or not, and having both positive and negative nonequilibrium temperatures temperatures T defined by (d Q / d S) E . Our novel approach to establish GSL/SL is the inverse of the one used in classical thermodynamics and clarifies the concept of spontaneous processes so that d S ≥ 0 for T > 0 and d S < 0 for T < 0 . Nonspontaneous processes such as creation of internal constraints are not covered by GSL/SL. Our demonstration establishes that Mec-EQ-P controls spontaneous processes, and that temperature (positive and negative) must be considered an integral part of dissipation. [ABSTRACT FROM AUTHOR]

In this paper, the fatigue resistance of a full-scale Steel Catenary Riser (SCR) girth weld is investigated using the Strength–Number of cycles (S–N) curve method based on weld formation quality and fracture mechanics approaches. The test results, presented in the form of S–N curves, are superior to the design curve E in BS 7608. Compared with the S–N curve determined by a resonant bending rig, the analytical fracture mechanics, i.e., engineering critical assessment (ECA) based on BS 7910, can provide a rational estimation of full-scale girth welds. For the numerical methods, the short crack growth phase is crucial to improving the accuracy and reliability of the assessment. For the girth weld with a concave root, the geometries of the weld cap are the predominant factors for fatigue life. Although the crack initiation site is always located at the outer surface regardless of the flushed or welded caps, the weld grinding treatment is still effective in promoting fatigue life. [ABSTRACT FROM AUTHOR]

The asphalt aging model is a crucial module in the Mechanistic-Empirical (ME) pavement design programme for asphalt pavement performance prediction. In this study, an analytical aging model that couples diffusion and kinetics aging model (CDKAM) is improved to analyze and predict the field aging of asphalt pavements. The complex modulus (E*) of field cores was used as the aging property to illustrate the derivation of explicit expressions of time-averaged thermal source term ( $ \overline {TST} (t) $ TST ¯ (t)) and time-averaged diffusion coefficient ( $ \bar{D}(t) $ D ¯ (t)). The value of the material-related parameter (M) in $ \overline {TST} (t) $ TST ¯ (t) model differs among different mixtures, which could assess the mixture's susceptibility to thermal oxidation. The CDKAM with $ \overline {TST} (t) $ TST ¯ (t) and $ \bar{D}(t) $ D ¯ (t) was used to predict E* of field aging for asphalt pavements in Texas after 22-month service life. The calibrated CDKAM could reasonably quantify the aging extent over time and the aging gradient over depth for studied asphalt pavements. [ABSTRACT FROM AUTHOR]

The article focuses on the development of controlled-release nanoliposomes to enhance the drug delivery of glatiramer acetate for multiple sclerosis treatment. Topics include the formulation and characterization of nanoliposomes, the evaluation of drug release kinetics and biosafety, and the potential therapeutic benefits of this delivery system.

Planning of a microtunneling project requires prediction of microtunnel boring machine (MTBM) performance. One of the main performance indicators of MTBMs is the penetration rate. The prediction of MTBM penetration rate is difficult due to the complex interaction between the cutterhead and soft ground. Although the engagement of the cutterhead with the ground highly influences the penetration rate, this phenomenon has not yet been thoroughly investigated from a mechanistic perspective. Hence, this research aims to analyze this phenomenon and develop a mechanistic model of MTBM penetration rate that considers the influence of cutterhead engagement with the ground. To study this interaction and evaluate its influence on MTBM penetration rate, this research proposes a novel approach based on the theory of contact mechanics and develops an analytical model that takes into consideration the area of engagement between the cutterhead and ground at the tunnel face. Through analytical analysis of MTBM engagement areas and in consideration of the largest and smallest engagement areas between the cutterhead and ground, upper and lower boundary models for MTBM penetration rate prediction are developed. Mechanistic modeling of engagement of the cutterhead with ground provides insight into its influence on the penetration rate of MTBMs and defines a relationship between the cutterhead engagement factor with other penetration rate influential factors (namely operational loads and soil properties), which enables engineers to improve the performance of MTBM excavation. Moreover, the development of penetration rate boundaries based on the amount of cutterhead engagement area can assist practitioners in reducing the uncertainty of penetration rate prediction. Analysis of a microtunneling project case study shows that the actual MTBM penetration rate lies between the upper and lower boundaries for the penetration rate as determined by the mechanistic model. [ABSTRACT FROM AUTHOR]

In human gait, leg progression into the swing phase involves two primary strategies: ankle plantar flexion and hip flexion. These strategies are believed to exhibit a trade-off relationship; however, it is unclear whether this relationship holds for normal gait and the role of the medial longitudinal arch (MLA) in shaping these strategies. Does a trade-off relationship exist between ankle plantar flexion and hip flexion strategies during normal gait in young healthy adults? Do the kinematics of MLA during gait influence the strategies during leg progression into the swing phase? Data from 36 young healthy adults were analyzed. Gait speed and peak moment, angular impulse, peak power and joint work at ankle plantar flexion and hip flexion were assessed within the context of the normal gait task. The parameters were also assessed using ankle-to-hip joint ratios (ankle/hip indices). Kinematics of MLA, including peak MLA angle, amount of descent, and amount of elevation during gait, were also measured. To exclude the effect of gait speed, partial correlation coefficients were employed to explore the relationship between ankle and hip variables as well as the ratio of ankle/hip indices and MLA kinematics. A significant negative correlation between ankle plantar flexion work and hip flexion work was detected. Moreover, a positive correlation between the ankle plantar flexion work to hip flexion work ratio and MLA elevation was detected. A trade-off relationship between ankle plantar flexion and hip flexion strategies during normal gait in young healthy adults was confirmed, suggesting that these parameters are fundamental to normal gait. Additionally, the MLA elevation during late stance may influence the establishment of ankle plantar flexion and hip flexion strategies. These findings enhance our understanding of gait mechanisms and highlight the role of MLA kinematics in shaping gait strategies. • The relationship between ankle and hip movement strategies in gait was examined. • The role of the medial longitudinal arch (MLA) in gait strategies was investigated. • Ankle plantar flexion work negatively correlated with hip flexion work. • MLA elevation was associated with gait strategies. • Ankle-hip trade-off is fundamental to gait and may be affected by MLA elevation. [ABSTRACT FROM AUTHOR]

We follow the Boltzmann-Clausius-Maxwell (BCM) proposal to establish the generalized second law (GSL) that is applicable to a system of any size, including a single particle system as our example establishes, and that supercedes the celebrated second law (SL) of increase of entropy of an isolated system. It is merely a consequence of the mechanical equilibrium (stable or unstable) principle (Mec-EQ-P) of analytical mechanics and the first law. We justify an irreversibility priciple that covers all processes, spontaneous or not, and having both positive and negative nonequilibrium temperatures temperatures T defined by (dQ/dS)E. Our novel approach to establish GSL/SL is the inverse of the one used in classical thermodynamics and clarifies the concept of spontaneous processes so that dS≥0 for T>0 and dS<0 for T<0. Nonspontaneous processes such as creation of internal constraints are not covered by GSL/SL. Our demonstration establishes that Mec-EQ-P controls spontaneous processes, and that temperature (positive and negative) must be considered an integral part of dissipation.

AbstractWe here introduce an analytical model for a preclinical femur-implant compound structure. This model extends standard Euler-Bernoulli-Saint-Venant theory by closed-form expressions for such shear stresses in thin-walled components, which arise from elastic material properties changing at the interfaces between bone and implant materials. Particularly noteworthy are stress singularities occurring at the generators of the cylindrical implants, which intersect the long axis of the bone shaft. This is fully consistent with observed major reorientations of bone fibrils following the implantation event, so that our novel mechanical model clearly indicates a case of micro-mechanobiology. [ABSTRACT FROM AUTHOR]

Introduction: Gastroesophageal reflux disease (GERD) is a chronic disease of the esophagus characterized by the regurgitation of stomach contents into the esophagus, causing troublesome symptoms and/or complications. Among patients with GERD, around 30% of patients have visible mucosal damage, while 70% have normal esophageal mucosa. Accordingly, the optimal pharmacological treatment of GERD should address different disease manifestations, including symptoms, the mucosal damage when present, and possible chronic complications, including strictures, Barrett's esophagus, and esophageal adenocarcinoma. Areas covered: Available medical treatments for GERD include proton pump inhibitors (PPIs), potassium-competitive acid blockers (PCABs), histamine receptor antagonists (H2-RAs), prokinetics, and mucosal protectants, such as alginates, hyaluronic acid/chondroitin-sulfate, and poliprotect. Each compound has its own advantages and disadvantages, and knowledge of expected benefits and tips for their use is paramount for the success of treatment. In addition, the appropriateness of indications for initiating treatment is also crucial to achieve positive results when managing GERD patients. Expert opinion: PPIs, PCABs, H2-RAs, prokinetics, and mucosal protectants can all be used in patients with GERD, but careful assessment of patients' characteristics as well as advantages and disadvantages of each therapeutic compound is essential to ensure successful treatment of GERD. [ABSTRACT FROM AUTHOR]

The D'Alembert–Lagrange principle is a fundamental concept in analytical mechanics that simplifies the analysis of multi-degree-of-freedom mechanical systems, facilitates the dynamic response prediction of structures under various loads, and enhances the control algorithms in robotics. It is essential for solving complex problems in engineering and robotics. This theoretical study aims to highlight the advantages of using acceleration energy to obtain the differential equations of motion and the generalized driving forces, compared to the classical approach based on the Lagrange equations of the second kind. It was considered a mechanical structure with two degrees of freedom (DOF), namely, a planar robot consisting of two homogeneous rods connected by rotational joints. Both the classical Lagrange approach and the acceleration energy model were applied. It was noticed that while both approaches yielded the same results, using acceleration energy requires only a single differentiation operation, whereas the classical approach involves three such operations to achieve the same results. Thus, applying the acceleration energy method involves fewer mathematical steps and simplifies the calculations. This demonstrates the efficiency and effectiveness of using acceleration energy in dynamic system analysis. By incorporating acceleration energy into the model, enhanced robustness and accuracy in predicting system behavior are achieved. [ABSTRACT FROM AUTHOR]

Most manual wheelchair users with pediatric-onset spinal cord injury (SCI) will experience shoulder pain or pathology at some point in their life. However, guidelines for preservation of the upper limb in children with SCI are limited. What are the relationships between manual wheelchair handrim kinetics and quantitative ultrasound parameters related to subacromial impingement in individuals with pediatric-onset SCI? Subacromial impingement risk factors including supraspinatus tendon thickness (SST), acromiohumeral distance (AHD), and occupation ratio (OR; SST/AHD) were measured with ultrasound in 11 manual wheelchair users with pediatric-onset SCI. Handrim kinetics were acquired during the stroke cycle, including peak resultant force (F R), peak rate of rise of resultant force (ROR) and fractional effective force (FEF). Variability of handrim kinetics was computed using the coefficient of variation and linear regression was performed to assess correlations between handrim metrics and quantitative ultrasound parameters. Peak resultant force significantly increased 1.4 % and variability of FEF significantly decreased 8.0 % for every 0.1 cm increase in AHD. FEF decreased 3.5 % for every 0.1 cm increase in SST. Variability of peak resultant force significantly increased 3.6 % and variability of peak ROR of resultant force significantly increased 7.3 % for every 0.1 cm increase in SST. FEF variability significantly decreased 11.6 % for every 0.1 cm increase in SST. Peak ROR significantly decreased 1.54 % with every 10 % increase in OR. FEF variability significantly decreased 1.5 % with every 10 % increase in OR. This is the first study to investigate relationships among handrim kinetics and shoulder structure in manual wheelchair users with pediatric-onset SCI. Associations were identified between subacromial impingement risk factors and magnitude and variability of wheelchair handrim kinetics. These results indicate the critical need to further explore the relationships among wheelchair handrim kinetics, shoulder joint dynamics, and shoulder pathology in manual wheelchair users with pediatric-onset SCI. • Wheelchair handrim kinetics are associated with risk of subacromial impingement. • Subacromial impingement risk decreases with increasing variability of handrim force. • Ultrasound can quantify risk factors of shoulder impingement in wheelchair users. • Supraspinatus tendon size correlates with handrim force variability and magnitude. • Subacromial occupation ratio decreases with increasing rate of force application. [ABSTRACT FROM AUTHOR]

Chronic ankle instability (CAI) has been associated with lower limb deficits that can lead to altered biomechanics during dynamic tasks. There have been contradictory findings in terms of ankle and hip joint biomechanics to date, influenced by the variety of movement tasks and varying definitions of the CAI condition. How do biomechanical variables of the lower extremity differ during walking, running, and jump-landing in individuals with CAI compared with those without CAI? Thirty-two individuals (17 CAI and 15 controls) participated in this retrospective case-control study. Sagittal and frontal plane ankle and hip joint angles and moments, and mediolateral foot balance (MLFB) were calculated during the tasks. Statistical parametric mapping (SPM) was used for the whole trajectory analysis to detect group differences. Discrete variables, including initial contact (IC) and peak angles and moments, were additionally compared. No differences were found between groups during walking. During running, the CAI group exhibited a lower plantar flexor moment (p < 0.001) and more laterally deviated MLFB (p = 0.014) during mid-stance when compared to controls. Additionally, participants with CAI had a significantly greater peak plantar flexion angle in early stance (p = 0.022) and a reduced peak plantar flexor moment (p = 0.002). In the jump-landing, the CAI group demonstrated an increased hip extensor moment (p = 0.008), and a greater peak hip adduction angle (p = 0.039) shortly after ground contact compared to the control group. Differences in ankle and hip biomechanics were observed between groups during running and jump landing, but not during walking. These differences may be indicative of impairments in the sensorimotor system or of learnt strategies adopted to try to minimise instability and injury risk and can help to inform future intervention design. • Individuals with CAI display different ankle joint biomechanics than controls during running. • Individuals with CAI display different hip joint biomechanics than controls during jump-landing. • The level of demand for the task may influence the biomechanical strategy adopted. [ABSTRACT FROM AUTHOR]

The Rossiter–McLaughlin effect measures the misalignment between a planet's orbital plane and its host star's rotation plane. Around 10 per cent of planets exhibit misalignments in the approximate range 80°–125°, with their origin remaining a mystery. On the other hand, large misalignments may be common in eccentric circumbinary systems due to misaligned discs undergoing polar alignment. If the binary subsequently merges, a polar circumbinary disc – along with any planets that form within it – may remain inclined near 90 |$^{\circ }$| to the merged star's rotation. To test this hypothesis, we present N -body simulations of the evolution of a polar circumbinary debris disc comprised of test particles around an eccentric binary during a binary merger that is induced by tidal dissipation. After the merger, the disc particles remain on near-polar orbits. Interaction of the binary with the polar-aligned gas disc may be required to bring the binary to the small separations that trigger the merger by tides. Our findings imply that planets forming in discs that are polar-aligned to the orbit of a high-eccentricity binary may, following the merger of the binary, provide a possible origin for the population of near-polar planets around single stars. [ABSTRACT FROM AUTHOR]

Managing novelty in perception-based human activity recognition (HAR) is critical in realistic settings to improve task performance over time and ensure solution generalization outside of prior seen samples. Novelty manifests in HAR as unseen samples, activities, objects, environments, and sensor changes, among other ways. Novelty may be task-relevant, such as a new class or new features, or task-irrelevant resulting in nuisance novelty, such as never before seen noise, blur, or distorted video recordings. To perform HAR optimally, algorithmic solutions must be tolerant to nuisance novelty, and learn over time in the face of novelty. This paper 1) formalizes the definition of novelty in HAR building upon the prior definition of novelty in classification tasks, 2) proposes an incremental open world learning (OWL) protocol and applies it to the Kinetics datasets to generate a new benchmark KOWL-718, 3) analyzes the performance of current stateof-the-art HAR models when novelty is introduced over time, 4) provides a containerized and packaged pipeline for reproducing the OWL protocol and for modifying for any future updates to Kinetics. The experimental analysis includes an ablation study of how the different models perform under various conditions as annotated by Kinetics-AVA. The code may be used to analyze different annotations and subsets of the Kinetics datasets in an incremental open world fashion, as well as be extended as further updates to Kinetics are released. [ABSTRACT FROM AUTHOR]

In this study, the removal of Malachite green (MG) dye, which has a toxic effect on the aquatic ecosystem, was carried out with kaolin clay, a natural and inexpensive material. In batch adsorption tests, the effects of pH, adsorbent dose, initial dye concentration and contact time were determined. Also, Pseudo first order and Pseudo second order kinetic models and Freundlich, Langmuir and Temkin isotherm models were tested. On the other hand, Scanning Electron Microscope (SEM) and Fourier Transform Infrared spectroscopy (FTIR) analyzes of raw and MG-loaded kaolin clay were performed. According to the results obtained, the removal efficiency was over 99% at 23±2 0C, pH 7.0 (±0.5), initial MG concentration of 4 mg/L and kaolin dosage of 1.75 g/L. Also, the most suitable kinetic and isotherm models were determined as Pseudo second order (R2: 0.999) and Freundlich (R2: 0.960), respectively. Additionally, the amount of MG dye removed per unit kaolin (qmax) was calculated as 16.36 mgMG/gkaolin. This study reveals the suitability of using kaolin clay in the adsorption of MG dye. [ABSTRACT FROM AUTHOR]

In this paper, we consider the long-term behavior of some special solutions to the Wave Kinetic Equation. This equation provides a mesoscopic description of wave systems interacting nonlinearly via the cubic NLS equation. Escobedo and Velázquez showed that, starting with initial data given by countably many Dirac masses, solutions remain a linear combination of countably many Dirac masses at all times. Moreover, there is convergence to a single Dirac mass at long times. The first goal of this paper is to give quantitative rates for the speed of said convergence. In order to study the optimality of the bounds we obtain, we introduce and analyze a toy model accounting only for the leading order quadratic interactions. [ABSTRACT FROM AUTHOR]

In this study, we conducted a kinetics simulation of TiB2 layers obtained by the boriding process in the temperature range of 1123-1323 K. To investigate the influence of different boriding parameters, we developed a mathematical model based on Fick's law and the mass balance equation. This model allows us to estimate the boron concentration in the TiB2 phase, the boride layer thickness, and the mass gain. To validate the simulation results, we compared them with our experimental data on liquid boriding with a salt bath consisting of 70 % Borax (Na2B4O7) and 30 % Silicon carbide (SiC) applied to the titanium alloy (Ti6Al4V). The comparison confirmed the validity of our model, assuring the accuracy of our simulation results. [ABSTRACT FROM AUTHOR]

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Chlorophyll a fluorescence, a sensitive and cost-effective probe, is widely used in photosynthetic research. Its rapid phase, occurring within 1 second under intense illumination, displays complex O-J-I-P transients, providing valuable insights into various aspects of photosynthesis. In addition to employing experimental approaches to measure the rapid Fluorescence Induction (FI) kinetics, mathematical modeling serves as a crucial tool for understanding the underlying mechanisms that drive FI dynamics. However, the significant uncertainty and arbitrary nature of selecting model parameters amplify concerns about the effectiveness of modeling tools in aiding photosynthesis research. Therefore, there is a need to gain a deeper understanding of how these models operate and how arbitrary parameter choices may influence their outcomes. In this study, we employed the Morris method, a global Sensitivity Analysis (SA) tool, to assess the significance of rate constants employed in an existing fluorescence model, particularly those linked to the entire electron transport chain, in shaping the rapid FI dynamics. In summary, utilizing the insights gained from the Morris SA allows for targeted refinement of the photosynthesis model, thereby improving our understanding of the complex processes inherent in photosynthetic systems. [ABSTRACT FROM AUTHOR]

Gas hydrate plugs in petroleum fluid pipelines are a major flow assurance problem and thus, it is important for industry to have reliable mathematical models for estimating the time required to dissociate a hydrate pipeline plug. The existing mathematical models for modelling hydrate plug dissociation treat the problem as a pure heat transfer problem. However, an early study by Jamaluddin et al. speculated that the kinetics of gas hydrate dissociation could become the rate-limiting factor under certain operating conditions. In this short communication, a rigorous 2D model couples the equations of heat transfer and fluid flow with Clarke and Bishnoi's model for the kinetics of hydrate dissociation. A distinguishing feature of the current work is the ability to predict the shape of the dissociating hydrate–gas interface. The model is used to correlate experimental data for both sI and sII hydrate plug dissociation, via single-sided depressurization and double-sided depressurization. As a preliminary examination on the necessity of including dissociation kinetics, this work is limited to conditions for which hydrate dissociation rate constants are available; kinetic rate constants for hydrate dissociation are available at temperatures above 273.15 K. Over the range of conditions that were investigated, it was found that including the intrinsic kinetics of hydrate dissociation led to only a very small improvement in the accuracy of the predictions of the cumulative gas volumes collected during dissociation. By contrast, a sensitivity study showed that the predictions of hydrate plug dissociation are very sensitive to the value of the porosity. Thus, it is concluded that unless values of the thermophysical properties of a hydrate plug are known, accounting for the dissociation kinetics need not be a priority. [ABSTRACT FROM AUTHOR]

The SH2 domains of SHP2 play a crucial role in determining the function of the SHP2 protein. While the folding and binding properties of the isolated NSH2 and CSH2 domains have been extensively studied, there is limited information about the tandem SH2 domains. This study aims to elucidate the folding and binding kinetics of the NSH2-CSH2 tandem domains of SHP2 through rapid kinetic experiments, complementing existing data on the isolated domains. The results indicate that while the domains generally fold and unfold independently, acidic pH conditions induce complex scenarios involving the formation of a misfolded intermediate. Furthermore, a comparison of the binding kinetics of isolated NSH2 and CSH2 domains with the NSH2-CSH2 tandem domains, using peptides that mimic specific portions of Gab2, suggests a dynamic interplay between NSH2 and CSH2 in binding Gab2 that modulate the microscopic association rate constant of the binding reaction. These findings, discussed in the context of previous research on the NSH2 and CSH2 domains, enhance our understanding of the function of the SH2 domain tandem of SHP2. [ABSTRACT FROM AUTHOR]

This paper introduces the Gibbs–Appell formalism into fluids. It devises the energy of acceleration of a perfect fluid surrounding a moving impermeable rigid body and the hydrodynamic forces acting on the body. The fluid is considered infinite, and the rigid body may have any closed tridimensional form. Therefore, the velocity field is non-divergent and irrotational; the density field is homogeneous in space and non-dependent on time, and all viscous effects are neglected. Under these assumptions, an explicit formulation for the hydrodynamic forces acting on the body is known as a-priori, and it is recovered in this text following an approach based on generalized quasi-velocities and the Gibss–Appell formalism, that may handle a vaster class of mechanical problems in comparison to Newtonian mechanics, especially non-holonomic constrained systems. The devised formulation is applied to the two-dimensional case study of a disc in unsteady rectilinear motion: the analytical form for the generalized hydrodynamic forces acting on the disc is evaluated, as well as the explicit formulae for the hydrodynamic coefficients of the body and the total energy of acceleration of the surrounding fluid. [ABSTRACT FROM AUTHOR]

The effectiveness of chemical oxidation depends on the type of cyanotoxins present in the water and varies with the water quality parameters. This study investigated four cyanotoxins to understand their reactions with conventional drinking water treatment plant oxidants and with advanced oxidation. Kinetic rate constants between saxitoxin, and two variants (dcSTX and neoSTX), and nodularin‐R with chlorine, monochloramine, permanganate, ozone, and hydroxyl radicals (UV‐H2O2) were developed under different pH and temperature conditions. Nodularin‐R kinetic rate constants were comparable to peer‐reviewed microcystin‐LR rate constants with reaction rates in the order of OH radicals > ozone >> chlorine > permanganate >> monochloramine. The speciation of saxitoxins with pH had a dominant effect on their reaction rates with the listed oxidants. Chlorine was the only oxidant effective for saxitoxins removal. The reaction rates of saxitoxins with OH radicals varied slightly with pH but were around two orders of magnitude less than microcystin‐LR's. [ABSTRACT FROM AUTHOR]

In this work, travelling wave solutions of a nonlinear system of fractional Schrödinger equations (FSEs) with conformable fractional derivatives are studied. We examine the fractional generalization of the Schrödinger equation, a topic of great importance in quantum physics, using the analytic approach known as the modified extended direct algebraic method. Our approach involves the use of a fractional complex transformation to produce nonlinear ordinary differential equations, which are then solved to reveal travelling wave solutions. The two- and three-dimensional graphs that provide visual representations of the system's behaviour present a variety of wave profiles, including periodic, kink, anti-kink, shocks, lumps, and other soliton waves. The study sheds light on the dynamics of FSEs by revealing multiple families of travelling wave solutions and their complex relationships. These results provide insight into nonlinear fractional partial differential equations and a greater understanding of the dynamics of FSEs than previous attempts in the literature. [ABSTRACT FROM AUTHOR]

This study delves into the mechanistic modelling of literature results for the adsorption of aqueous Pb(II) by metabolically inhibited bacterial cultures from the industrial sector. Employing a multi-compartmented mathematical model based on Langmuir's mechanistic multi-surface adsorption, the study explores the adsorption process onto multiple heterogeneous surfaces operating simultaneously. The mathematical model is elucidated, and its parameters are optimized using experimental data obtained from various biosorbents. The results highlight the efficacy of the proposed multi-surface Langmuir kinetic models in predicting the adsorption kinetics of Pb(II) for diverse adsorbents. The study underscores the potential of multi-surface Langmuir modelling in capturing surface heterogeneity. The sensitivity analysis reveals the models' responsiveness to variations in adsorption rate constants (kad), emphasizing the necessity of precise parameterization for robust predictions. These sensitivities have significant implications for the accurate modelling of Pb(II) adsorption kinetics, guiding advancements in effective wastewater treatment strategies. [ABSTRACT FROM AUTHOR]

In the face of growing environmental challenges and the urgent need for sustainable solutions, this research delves into an innovative approach to wastewater treatment by harnessing the power of agricultural waste materials as efficient adsorbents. The focuses on mitigating water pollution and bringing irrigation water quality in line with strict maximum permissible limits (MPLs). Initial assessments revealed elevated levels of contaminants, all exceeding MPLs. Among ten adsorbent materials tested, Rice Husk Ash (RHA), Sugarcane Bagasse (SB), and Ferric Oxide Sand (Fe-S), emerged as highly effective materials, achieving maximum reductions. Optimized conditions for adsorbent dosage, contact time, and wastewater load were identified which was 2.0 g of adsorbent, 250 mL of sewage water load at 15 min contact time. RHA demonstrated a remarkable 60-75% reduction in BOD, 52-67% in COD, and over 100% in RSC reduction. SB achieved reductions of 57-67% in BOD, 47-59% in COD, and 41-76% in RSC. Fe-S delivered significant reductions in COD (51-61%) and nearly 100% in RSC reduction. Kinetic studies confirmed pseudo-second-order kinetics as the dominant adsorption mechanism, with correlation coefficients (R²) exceeding 0.98, further supporting the effectiveness of these adsorbents. This research underscores the potential of agricultural waste-based adsorbents, especially RHA and SB, in treating sewage water pollutants and making it fit for irrigation. [ABSTRACT FROM AUTHOR]

This study aimed to determine the isotherm, kinetics, and thermodynamics of Remazol Yellow FG adsorption by ZnCl2-activated bamboo charcoal. The research began with preparing activated charcoal from bamboo stems using ZnCl2, and then the quality was characterized according to the SNI. The adsorption isotherms were tested against Langmuir and Freundlich models, and the kinetics were examined for pseudo-first and pseudo-second orders. The thermodynamic parameters, which were enthalpy (ΔH°), entropy(ΔS°), and free energy (ΔG°), were also determined. The results showed that the adsorption followed the Langmuir isotherm with the adsorption capacity of 45.4545 mg/g, and the kinetic model corresponded to the pseudo-second order. The values of ΔH°, ΔS°, and ΔG° using different concentrations of Remazol Yellow RG of 100 and 300 mg/L at the optimum conditions of contact time of 240 minutes, the temperature of 303K, and pH 2 were -99.768 and - 83.971 KJ/mol; - 0.302 and - 0.239 KJ/mol; -8.383 and -11.433 KJ/mol, respectively. The adsorption was exothermic (ΔH° < 0), followed by a decrease in entropy (ΔSo < 0), and the process was spontaneous (ΔG° < 0) and controlled by chemical adsorption. [ABSTRACT FROM AUTHOR]

Robotic Roller Forming (RRF) is a novel process using an articulated robotic manipulator that can bend Ultra-High Strength materials into thin-walled profiles. For high strength or difficult-to-form sheet materials, a laser can be employed to synchronously heat and soften the local material during RRF. The aim of RRF is to establish itself as a highly flexible process for rapid prototyping as well as for small batch production. However, in finished parts formed with different materials, a new defect that shapes the profile like that of a hook was observed. To overcome this defect and to improve the adaptability of the process, a new analytical model is suggested for the automatic calculation of the tool center point based on the given process parameters. The model was compared to the previous state, where the hook defect was noticeably reduced. Additionally, the control of the bend radius was studied, and the resulting bend radius diverged from the target radius by 0.04 mm (2.45%). Further, when examining the reproducibility, the same bend angles could be achieved as in previous experiments using the constant laser power density. Finally, the development of the bend allowance was studied in various experiments. The analytical model for RRF is a promising method for calculating tool placement and controlling the bend radius in a freeform environment. [ABSTRACT FROM AUTHOR]

Within the various approaches to organic waste handling, composting has been recognized as an acceptable method to valorize organic waste. Composting is an aerobic technique of microbial disruption of organic matter which results with compost as a final product. To guarantee the quality of the compost, key process factors (like the moisture content, temperature, pH, and carbon-to-nitrogen ratio) must be maintained. In order to optimize the process, nine composting trials using grape skins were conducted in the present study under various initial moisture content and air flow rate conditions over the course of 30 days. The processes were monitored through physicochemical variables and microbiological activity. Also, the kinetics of the organic matter degradation and microbial growth were investigated. Although the thermophile phase was only achieved in experiments 3 and 8, the important variables proved the efficiency of all nine composting processes. The organic carbon content and C/N ratio decreased after the 30 days of composting processes and a great color change was noticed too. The values for the germination index for all experiments were above 80%, which means that the final products are non-toxic for plants. Also, the greatest change in organic carbon content in was evident in experiment 3; it decreased from 71.57 to 57.31%. And consequently, the rate of degradation for that experiment was the highest, at 0.0093 1/day. Furthermore, the response surface methodology was used to identify optimal operating conditions for grape skin composting and the obtained conditions were 58.15% for the initial moisture content and 1.0625 L/min for the air flow rate. [ABSTRACT FROM AUTHOR]

Nanopatterned tribocharge can be generated on the surface of elastomers through their replica molding with nanotextured molds. Despite its vast application potential, the physical conditions enabling the phenomenon have not been clarified in the framework of analytical mechanics. Here, we explain the final tribocharge pattern by separately applying two models, namely cohesive zone failure and cumulative fracture energy, as a function of the mold nanotexture's aspect ratio. These models deepen our understanding of the triboelectrification phenomenon. [ABSTRACT FROM AUTHOR]

In recent years, global attention towards new energy has surged due to increasing energy demand and environmental concerns. Researchers have intensified their focus on new energy, leading to advancements in technologies like triboelectrification, which harnesses energy from the environment. The invention of the triboelectric nanogenerator (TENG) has led to new possibilities, with the rotary sliding TENG standing out for its superior performance. However, understanding its mechanical behavior remains a challenge, potentially leading to structural issues. This paper introduces a novel analytical mechanics model to analyze the mechanical performance of the stator of the rotary sliding TENG, offering a new analytical solution. The solution also presents an innovative approach to solving axisymmetric problems in elasticity theory since it challenges a traditional assumption that the stress function depends solely on the radial coordinate, proposing a new stress function to derive a more general solution, supplementing the classical approach in the theory of elasticity. Through the obtained solutions, the mechanical characteristics of the rotary sliding TENG during operation are analyzed. A clearer relationship between mechanical characteristics and electrical output is expected to provide a theoretical basis for the design of the rotary sliding TENG. [ABSTRACT FROM AUTHOR]

The present paper describes, in a theoretical fashion, a variational approach to formulate fourth-order dynamical systems on differentiable manifolds on the basis of the Hamilton–d'Alembert principle of analytic mechanics. The discussed approach relies on the introduction of a Lagrangian function that depends on the kinetic energy and the covariant acceleration energy, as well as a potential energy function that accounts for conservative forces. In addition, the present paper introduces the notion of Rayleigh differential form to account for non-conservative forces. The corresponding fourth-order equation of motion is derived, and an interpretation of the obtained terms is provided from a system and control theoretic viewpoint. A specific form of the Rayleigh differential form is introduced, which yields non-conservative forcing terms assimilable to linear friction and jerk-type friction. The general theoretical discussion is complemented by a brief excursus about the numerical simulation of the introduced differential model. [ABSTRACT FROM AUTHOR]

In this work, a two-dimensional computational fluid dynamic (CFD) model is developed to describe the drying process of a packed bed made of spherical particles. The volumetrical evaporation rate inside the bed is computed from the pressure difference between the particle surface and the airflow. By using the thermal equilibrium assumption, the heat conservation equation is derived. The CFD model is solved in the COMSOL Multiphysics environment. The obtained results indicate remarkable maldistributions of temperature and moisture content. These maldistributions can be explained by the impact of lateral edges on thermo-hydraulic behavior. Additionally, the impact of particle diameter, air velocity, and bed width on the spatial-temporal moisture content and temperature distribution is investigated. It shows that the CFD model can be simplified to the receding front drying model for a bed made of small particles. Furthermore, by changing the thermal boundary conditions at the lateral edges, the influence of the heating mode at the lateral edges on the drying behavior is explored. The results indicate that contact heating at the bed wall can help to accelerate the drying process significantly. [ABSTRACT FROM AUTHOR]

For the particular case of an elastic multibody system (MBS) that can be modeled using one-dimensional finite elements, the main methods offered by analytical mechanics in its classical form for analysis are presented in a unitary description. The aim of the work is to present in a unitary form the main methods offered by classical mechanics for the analysis of solid systems. There is also a review of the literature that uses and highlights these methods, which need to be reconsidered considering the progress of the industry and the complexity of the studied systems. Thus, the kinematics of a finite element is described for the calculation of the main quantities used in the modeling of multibody systems and in analytical mechanics. The main methods used in the research of MBS systems are presented and analyzed. Thus, Lagrange's equations, Gibbs–Appell equations, Maggi's formalism, Kane's equations and Hamilton's equations are studied in turn. This presentation is determined by the advantages that alternatives to Lagrange's equations can offer, which currently represent the method most used by researchers. [ABSTRACT FROM AUTHOR]

This article aims to enhance the control efficiency of the Permanent Magnet Synchronous Motor (PMSM) by generating optimal reference currents idref and iqref using Ant Colony Optimization (ACO), while ensuring a minimal absorbed current condition to reduce energy consumption and optimize PMSM performance. The ACO algorithm is chosen for its ability to find global solutions and robustness in complex environments, while Sliding Mode Control (SMC) provides advantages in terms of robustness against disturbances and the ability to maintain the system in a desired state. The implementation of the processor-in-the-loop (PIL) technique using MATLAB software with code composer and the LAUNCHXLF28069M board enables the controller to be implemented in real hardware (LAUNCHXL-F28069M) to test the simulation environment (inverter and PMSM). Our results demonstrate the efficiency of ACO compared to the analytical method (AM) in terms of response time and minimizing absorbed current for different load values. Artificial intelligence (AI) has successfully and efficiently addressed the non-linearity between torque and reference currents, thus reducing energy consumption. This has allowed for the optimization of PMSM performance in a straightforward and efficient manner. [ABSTRACT FROM AUTHOR]

The paper aims to use the Gibbs-Appell equations to obtain the evolution equations of a finite element (FE) to solve a problem that is becoming more and more current in the context of the accelerated use of composite materials in engineering. It is the problem of modeling materials with voids, which appear accidentally or are intentionally introduced into a material. In general, Lagrange's equations represent the most used mathematical tool for solving such cases. The complexity of current engineering applications, in which numerous parameters must be taken into account and numerous steps must be completed in the modeling activity, make some of the classical methods of Analytical Mechanics to be reconsidered, in order to take advantage of the particularities offered by them. This can reduce the number of procedures to follow in modeling the system and also reduce the amount of computation required (and costs). In this context the Gibbs-Appell method is used to finally obtain the equations of motion for a material with voids. For example, it can be noted that for a concentration of voids of 4% the stresses increase by 12%. [ABSTRACT FROM AUTHOR]

This paper is an analytical review in which we present quaternion and biquaternion methods for describing motion, models of the theory of finite displacements and regular kinematics of a rigid body based on the use of four-dimensional real and dual Euler (Rodrigues–Hamilton) parameters. These models, in contrast to the classical models of kinematics in Euler–Krylov angles and their dual counterparts, do not have division-by-zero features and do not contain trigonometric functions, which increases the efficiency of analytical research and numerical solution of problems in mechanics, inertial navigation, and motion control. The problem of regularization of differential equations of the perturbed spatial two-body problem, which underlies celestial mechanics and space-flight mechanics (astrodynamics), is discussed using the Euler parameters, four-dimensional Kustaanheimo–Stiefel variables, and Hamilton quaternions; this problem consists in eliminating the singularities (division by zero) which are generated by the Newtonian gravitational forces acting on a celestial or cosmic body and which complicate the analytical and numerical study of the motion of a body near gravitating bodies or its motion along highly elongated orbits. The history of the regularization problem and the regular Kustaanheimo–Stiefel equations, which have found wide application in celestial mechanics and astrodynamics, are presented. We present the quaternion methods of regularization, which have a number of advantages over Kustaanheimo–Stiefel matrix regularization, and various regular quaternion equations of the perturbed spatial two-body problem (for both absolute and relative motion), which are useful for predicting and correcting the orbital motion of celestial and cosmic bodies. [ABSTRACT FROM AUTHOR]

This study is dedicated to an investigation and comparison of the kinetics of the foam stability of protein foaming agents based on the hydrolysates of solid keratin. The work utilized ready-made hydrolysates based on sodium hydroxide and a mixture of sodium hydroxide with calcium hydroxide for the synthesis of foaming agents. The synthesis was carried out according to the author's methodology. Among the indicators studied were foam multiplication, foam specific weight, foam stability over time, and average foam stability reduction rate. Experiments were conducted with various concentrations and ratios of components at constant temperature, pressure, and pH values, as well as mixing speed, mixing time, and observation time. Itis hypothesized that protein foaming agents based on hydrolysates of solid keratin using a mixture of hydroxides will not be able to achieve optimal values in the kinetics of foam stability. In contrast, protein foaming agents based on hydrolysates of solid keratin using sodium hydroxide individually have high potential foaming properties and, consequently, good foam stability kinetics indicators. The results of this study may be useful in the development of new synthesis methods for protein foaming agents with optimal foaming properties or for improving those that already exist. The research itself and the products obtained during it—protein foaming agents—are mainly aimed at expanding the industrial sphere of human activity. This may also have practical applications in other areas, such as the food industry, cosmetology, medicine, and others. [ABSTRACT FROM AUTHOR]