Evolution Of Parameters Research Articles

Probing entanglement dynamics and topological transitions on noisy intermediate-scale quantum computers

We simulate quench dynamics of the Su-Schrieffer-Heeger (SSH) chain on IBM quantum computers, calculating the Rényi entanglement entropy, the twist order parameter, and the Berry phase. The latter two quantities can be deduced from a slow-twist operator defined in the Lieb-Schultz-Mattis theorem. The Rényi entropy is obtained using a recently developed randomized measurement scheme. The twist order parameter and the Berry phase are measured without the need for additional gates or ancilla qubits. We consider quench protocols in which a trivial initial state evolves dynamically in time under the topological SSH Hamiltonian in the fully dimerized limit (the flat-band limit). During these quenches, there are persistent and periodic oscillations in the time evolution of both entanglement entropy and twist order parameter. Through the implementation of error mitigation techniques using a global depolarizing ansatz and postselection, our simulations on the IBM devices yield results that closely match exact solutions. Published by the American Physical Society 2025

Raman signatures of inversion symmetry breaking structural transition in quasi-1D compound, (TaSe4)3I.

The breaking of inversion symmetry combined with spin-orbit coupling, can give rise to intrigu-
ing quantum phases and collective excitations. Here, we report systematic temperature dependent
Raman scattering and theoretical calculations of phonon modes across the inversion symmetry-
breaking structural transitions in a quasi-one-dimensional compound (TaSe4)3I. Our investigation
revealed the emergence of three additional Raman-active modes in Raman spectra of the low-
temperature (LT) non-centrosymmetric (NC) structure of the material. From polarization depen-
dent Raman spectra and phonon mode symmetry analysis, we have identified the origin of these
three newly appeared additional Raman-active modes. Notably, two of these modes become Raman
active due to the loss of inversion symmetry, while the third mode is identified as a soft phonon mode,
arising from the distinctive vibrational motion of tantalum (Ta) atoms along the -Ta-Ta- chains.
Furthermore, the temperature evolution of self-energy parameters indicates significant changes in
the characteristics of the Raman modes across the transition. Latent heat measurements near the
phase transition using Differential Scanning Calorimetry (DSC) confirm the first-order nature of
the transition. Theoretical analysis, including group theory and modeling, reaffirms the displacive
first-order nature of the structural transition. Our findings establish (TaSe4)3I as a model quasi-
one-dimensional system with broken inversion symmetry facilitated through a displacive first-order
structural transition.

Evolution of Physical Self-Esteem During Pulmonary Rehabilitation in Patients with Chronic Obstructive Pulmonary Disease: An Observational Study.

Background/Objectives: Patients with COPD have altered self-esteem, and good self-esteem promotes personal, health, and social success. Improving self-esteem could be a method for encouraging the maintenance of physical activity. Only one study has evaluated the effects of pulmonary rehabilitation (PR) on self-esteem in moderate COPD patients. The objective was to assess the evolution of self-esteem in COPD patients of all stages of severity during PR. Methods: COPD patients undergoing PR were included in this prospective observational study. Patients were evaluated before and after the 4-week PR program. The objectives were to (1) assess the evolution of self-esteem using the Physical Self Inventory-6 questionnaire (PSI-6), (2) assess the evolution in each sub-score of PSI-6, (3) examine the correlations between the evolution of self-esteem and the evolution of parameters usually used during PR, and (4) determine an MID for self-esteem. Results: In total, 76 patients were included. We found that there was a significant increase in the total score in PSI-6 (9.29, p < 0.001), CI 95% [6.74; 11.83], and in the sub-scores of PSI-6. The evolution of the PSI-6 score was moderately correlated with changes in exercise capacity using STST1 (r = 0.352, p = 0.002) and quality of life (r = -0.361, p = 0.001) and weakly correlated to changes in dyspnea (r = -0.245, p = 0.03), anxiety (r = -0.248, p = 0.03), and depression (r = -0.290, p = 0.01). Using a distribution-based analysis, we found an MID between 5.2 and 5.6. Conclusions: We showed a significant increase in global score and in each sub-score of self-esteem using PSI-6 in COPD patients undergoing a PR program. We propose an MID of 5.6.

Sensitivity Analysis of the Johnson-Cook Model for Ti-6Al-4V in Aeroengine Applications

Titanium alloys, such as Ti-6Al-4V, are crucial for aeroengine structural integrity, especially during high-energy events like turbine blade-out scenarios. However, accurately predicting their behavior under such conditions requires the precise calibration of constitutive models. This study presents a comprehensive sensitivity analysis of the Johnson-Cook plasticity and progressive damage model parameters for Ti-6Al-4V in blade containment simulations. Using finite element models, key plasticity parameters (yield strength (A), strain-hardening constant (B), strain-rate sensitivity (C), thermal softening coefficient (m), and strain-hardening exponent (n)) and damage-related parameters (d1, d2, d3, d4, and d5) were systematically varied by ±5% to assess their influence on stress distribution, plastic deformation, and damage indices. The results indicate that the thermal softening coefficient (m) and the strain rate hardening coefficient (C) exhibit the most significant influence on the predicted casing damage, highlighting the importance of accurately characterizing these parameters. Variations in yield strength (A) and strain hardening exponent (n) also notably affect stress distribution and plastic deformation. While the damage evolution parameters (d1–d5) influence the overall damage progression, their individual sensitivities vary, with d1 and d4 showing more pronounced effects compared to others. These findings provide crucial guidance for calibrating the Johnson-Cook model to enhance aeroengine structural integrity assessments.

Anisotropic Cosmic Expansion Inspired by Some Novel Holographic Dark Energy Models in f(Q)$f(Q)$ Theory

AbstractThe present work discusses the topic of cosmic evolution in an intriguing framework of theory of gravity (with as a non‐metricity (NM) scalar which controls the gravitational interaction) by using some recently proposed holographic dark energy (HDE) models. To achieve this goal, the dynamical equations for locally rotationally symmetric (LRS) Bianchi type‐I (BI) geometry are formulated with matter contents as a mixture of dust and anisotropic fluids. By assuming that the time‐redshift relation follows a Lambert function, the cosmological model is constructed by using Rényi HDE (RHDE), Sharma–Mittal HDE (SMHDE) and Generalized HDE (GHDE) as separate cases where Hubble horizon is taken as an infrared (IR) cutoff. Cosmological characteristics of these models are then examined through graphs of energy densities, skewness parameter , deceleration, and EoS parameters. The evolution of the EoS parameter is also studied, i.e., to discuss the dynamical characteristics of constructed DE models and assess the stability of models via the squared speed of sound parameter. It is found that the plane shows the freezing region for RHDE and GHDE models while the thawing region for the SMHDE case. Also, it is concluded that all constructed models exhibit cosmologically viable and stable behavior.

The Influence of Strength and Skill Parameters on the Evolution of Dysphagia Post Stroke: A Prospective Study.

The role of pathophysiological deficits in the evolution of dysphagia post-stroke is unclear. This observational, longitudinal study aimed to document the evolution and relationship between strength and precision of submental contraction, and swallowing outcomes at six months. Participants were recruited from a tertiary acute hospital after a first acute stroke. Sociodemographic data and stroke typology were documented. Outcome measures were collected five times across six months. These included: oral diet (FOIS, IDDSI), functional ingestion (TOMASS, TWST), self-reported swallowing-related quality of life (SWAL-QOL), and submental muscle strength and precision contraction as assessed using surface electromyography coupled with biofeedback during saliva swallowing and jaw-opening tasks. Mixed effects models and multiple regressions analyses were conducted. Participants (N = 22, mean age 73.9 ± 14.4 years, 9 males) were recruited at a mean time of 2.8 ± 1.5 days after stroke. Strength parameters (effortful swallow hit rate) improved between ten days and one month post-stroke (p = 0.04). Swallowing temporal precision improved significantly between one and six months (p < 0.01). At six months, participants with decreased swallowing precision also had decreased quality of life (p = 0.04) and increased ingestion time of fluids (p = 0.002). This study is a novel step in exploring the nature and evolution of strength and precision parameters of swallowing muscle activation, and their impact on dysphagia recovery. As swallowing precision was associated with poorer functional outcomes, further studies are warranted to improve early differential diagnosis of patients at risk of chronic dysphagia.

Using 3D immersive virtual reality interactive tasks for upper limb rehabilitation in children with cerebral palsy: A randomized controlled trial

ABSTRACT The aim of this study was to investigate the effects of the virtual reality device on the evolution of motivation, and motor, functional and kinematic parameters of the upper limb in children with cerebral palsy. Twenty children were randomly assigned in VR and control groups. VR group scored higher than the control group in the Movement Assessment Battery for Children – Second Edition (MABC-2; standardized motor skills test), exhibited an increased range of motion, and showed improved results in various movement parameters in the interaction with the 3D virtual space. All participants presented high motivation scores in the iVR sessions. This new Immertrack tool may improve the motor, kinematic parameters, and motivation in children with CP.

Perturbational Decomposition Analysis for Quantum Ising Model with Weak Transverse Fields.

This work presents a perturbational decomposition method for simulating quantum evolution under the one-dimensional Ising model with both longitudinal and transverse fields. By treating the transverse field terms as perturbations in the expansion, our approach is particularly effective in systems with moderate longitudinal fields and weak to moderate transverse fields relative to the coupling strength. Through systematic numerical exploration, we characterize parameter regimes and evolution time windows where the decomposition achieves measurable improvements over conventional Trotter decomposition methods. The developed perturbational approach and its characterized parameter space may provide practical guidance for choosing appropriate simulation strategies in different parameter regimes of the one-dimensional Ising model.

A self-learning magnetic Hopfield neural network with intrinsic gradient descent adaption

Physical neural networks (PNN) using physical materials and devices to mimic synapses and neurons offer an energy-efficient way to implement artificial neural networks. Yet, training PNN is difficult and heavily relies on external computing resources. An emerging concept to solve this issue is called physical self-learning that uses intrinsic physical parameters as trainable weights. Under external inputs (i.e., training data), training is achieved by the natural evolution of physical parameters that intrinsically adapt modern learning rules via an autonomous physical process, eliminating the requirements on external computation resources. Here, we demonstrate a real spintronic system that mimics Hopfield neural networks (HNN), and unsupervised learning is intrinsically performed via the evolution of the physical process. Using magnetic texture-defined conductance matrix as trainable weights, we illustrate that under external voltage inputs, the conductance matrix naturally evolves and adapts Oja's learning algorithm in a gradient descent manner. The self-learning HNN is scalable and can achieve associative memories on patterns with high similarities. The fast spin dynamics and reconfigurability of magnetic textures offer an advantageous platform toward efficient autonomous training directly in materials.

Effects of the Hot-Drawing Process on the Pore Parameters, Gas Absorption and Mechanical Performances of Activated Carbon-Loaded Porous Poly(m-Phenylene Isophthalamide) Composite Fibres.

Poor breathability, inadequate flexibility, bulky wearability, and insufficient gas-adsorption capacity always limit the developments and applications of conventional chemical protective clothing (CPC). To create a lightweight, breathable, and flexible fabric with a high gas-absorption capacity, activated carbon (AC)-loaded poly(m-phenylene isophthalamide) (PMIA) porous composite fibres were fabricated from a mixed wet-spinning process integrated with a solvent-free phase separation process. By manipulating the pore parameters of as-spun composite fibres, the exposure-immobilization of AC particles on the fibre surface can offer a higher gas-absorption capacity and better AC-loading stability. To improve the mechanical properties of AC-loaded porous as-spun fibres and further optimize the pore-locking structures, the impact of the hot-drawing process on the evolution of pore parameters and the corresponding properties (including the gas absorption capacity, the mechanical performance, and the stability of AC particles during loading) was clarified. After the hot-drawing process, the inhomogeneous pore morphologies composed of mesopores/micropores from as-spun fibres changed into homogeneous and decreased mesopores. With the decrease in structural defects in homogeneous morphologies, the tensile strength of AC-loaded PMIA porous-drawn fibres increased to 1.5 cN/dtex. Meanwhile, the greater total pore volume and specific surface area after hot drawing also maintained the gas-absorption capacity of drawn composite fibres at 98.53 mg/g. Furthermore, the AC-loaded PMIA porous composite fibres also showed comparable performance to the commercial FFF02 absorption layer in terms of static absorption behaviour for different gas molecules and absorption-desorption multi-cycling evaluations. In addition, due to the size reduction in mesopores after the hot-drawing process, the loading stability of AC particles in the stretched composite fibres was more substantial.

A Comparative Study of the Electroneurographic Findings in Amyloidotic Polyneuropathy in Patients with Light-Chain Amyloidosis and Glu54Gln Transthyretin Amyloidosis

Background and Objectives: Amyloidosis is a disorder characterized by the abnormal folding of proteins, forming insoluble fibrils that accumulate in tissues and organs. This accumulation disrupts normal tissue architecture and organ function, often with serious consequences, including death if left untreated. Light-chain amyloidosis (AL) and hereditary transthyretin-type amyloidosis (hATTR) are two of the most common types. In amyloidosis, peripheral nervous system involvement is a significant diagnostic feature, particularly when it manifests as polyneuropathy, carpal tunnel syndrome (CTS), and dysautonomia. These neurological symptoms often point to the involvement of amyloid deposits in the peripheral and autonomic nervous systems, which can help identify and differentiate between the various types of amyloidosis. Materials and Methods: This retrospective study focused on the evolution of electrophysiological parameters in two groups: AL (n = 22) and hATTR-Glu54Gln patients (n = 14), with mixed axonal polyneuropathy. Patients were followed for two consecutive years to assess disease progression. The PND scale (polyneuropathy disability) was also used to assess motor impairment for each patient. Results: In our study AL amyloidosis patients presented with mixed, axonal polyneuropathy associated with CTS in 63.6% of cases and cardiomyopathy (45.5%). Serial EMGs (electromyography) showed decreased motor amplitudes of the common peroneal and tibial nerves and sensory amplitude of the superficial peroneal nerve, with mostly preserved conduction velocities. The patients maintained stage I PND throughout the monitoring period. The entire hATTR group displayed mixed, axonal polyneuropathy and cardiomyopathy; 85.7% of them had CTS, and 42.9% had orthostatic hypotension. EMG data showed decreased motor amplitudes of the tibial and common peroneal nerves, decreased sensory amplitudes of the superficial peroneal nerve, and mildly reduced conduction velocities, with significant progression at 12 and 24 months. The patients displayed additional reduced muscle strength, some reaching stage 3A and 3B-PND at the end of the study. Conclusions: The amyloidotic polyneuropathy found in the groups was similar in its axonal, sensory-motor, and length-dependent characteristics, but the study showed significant differences in its progression, with more abrupt changes in the hATTR-Glu54Gln group. The amyloidosis AL patients remained in stage 1 PND, while the hATTR-Glu54Gln patients progressed to stage 3 PND at 24 months.

Non-flat Friedmann-Lemaitre-Robertson-Walker universe with Barrow holographic dark energy

In this paper, we study a non-flat Friedmann-Lemaitre-Robertson-Walker (FLRW) universe filled with cold dark matter and Barrow holographic dark energy. We assume the Hubble horizon as IR cutoff and the scale factor to obey a hybrid expansion law to construct a cosmological model within the framework of General Relativity. The physical and geometrical properties of the model are discussed by studying the evolution of various parameters of cosmological importance. The behaviour of the dark energy equation of state parameter wDE is also studied for both interacting and non-interacting Barrow holographic dark energy. We observe that the Barrow exponent ∆ significantly affects the dark energy equation of state parameter which in turn exhibits the behaviour of quintessence and phantom dark energy. The evolution of the jerk parameter is also studied.

Evolution of Sow Productivity and Evaluation Parameters: Spanish Farms as a Benchmark.

This study examines the global evolution of sow productivity, with a particular focus on Spain. The analysis is based on key performance metrics such as piglets weaned per sow per year (PWSY), prolificacy, and pre-weaning mortality, utilizing data from literature reviews, the InterPIG, and BDporc® databases. Globally, significant advancements in genetic selection and management practices have led to productivity increases across major pig-producing countries, with notable improvements in prolificacy. However, higher prolificacy has been accompanied by rising piglet mortality rates during lactation, posing sustainability challenges. In Spain, the average productivity of commercial sows increased from 23.78 PWSY in 2009 to 29.45 PWSY in 2023, while Iberian sows reached an average of 17.44 PWSY. Despite these gains, Spain's figures remain slightly below the European Union average. The study highlights the need for new benchmarks, such as non-productive days, piglet survival, and sow longevity, to more accurately assess farm efficiency. These indicators, combined with considerations for animal welfare and environmental sustainability, are crucial for addressing current challenges such as piglet mortality, sow culling, and the carbon footprint. The findings emphasize the importance of adopting comprehensive management strategies that balance productivity with growing social and environmental demands on the swine industry.

Full Spectrum Electrochromic WO3 Mechanism and Optical Modulation via Ex Situ Spectroscopic Ellipsometry: Effect of Li+ Surface Permeation.

Tungsten oxide (WO3) electrochromic devices are obtaining increasing interest due to their color change and thermal regulation. However, most previous work focuses on the absorption or transmission spectra of materials, rather than the optical parameters evolution in full spectrum in the electrochromic processes. Herein, we developed a systematic protocol of ex situ methods to clarify the evolutions of subtle structure changes, Raman vibration modes, and optical parameters of WO3 thin films in electrochromic processes as stimulated by dosage-dependent Li+ insertion. We obtained the below information by ex situ spectroscopic ellipsometry. (1) Layer-by-layer Li+ embedding mechanism demonstrated by individual film thickness analysis. (2) The details of its optical leap in the Brillouin zone in the full spectral. (3) The optical constants varied with the Li+ insertion in the ultraviolet, visible, and near-infrared bands, demonstrating the potential for applications in chip fabrication, deep-sea exploration, and optical measurements. (4) Simulated angular modulation laws of WO3 films for full spectra in different Li+ insertion states. This ex situ method to study the optical properties of electrochromic devices are important for monitoring phase transition kinetics, the analysis of optical leaps, and the study of ion diffusion mechanisms and the stoichiometry-dependent changes in optical constants over the full spectral. This work shows that electrochromic films in Li+ surface permeation can be applied in the field of zoom lenses, optical phase modulators, and other precision optical components. Our work provides a new solution for the development of zoom lenses and a new application scenario for the application of electrochromic devices.

Effect of bridgmanite-ferropericlase grain size evolution on Earth’s average mantle viscosity: implications for mantle convection in early and present-day Earth

Recent experimental investigations of grain size evolution in bridgmanite-ferropericlase assemblages have suggested very slow growth for these bimodal phases. Despite numerous speculations on grain size-dependent viscosity, a comprehensive test with realistic grain size evolution parameters compatible with the lower mantle has been lacking. In this study, we develop self-consistent 2-D spherical half-annulus geodynamic models of Earth’s evolution using the finite volume code StagYY to assess the role of grain size on lower mantle viscosity. We explore several models with and without grain size evolution to compare their effects on mantle viscosity. In models with grain size evolution, we consider three scenarios: (1) uniform grain growth throughout the entire mantle with a composite rheology, (2) different grain growth in the upper and lower mantle with a composite rheology, and (3) different grain growth in the upper and lower mantle with purely diffusion creep rheology. In the case of different grain size evolution, the upper mantle’s grain size evolution law is controlled by forsterite-enstatite grain growth, while the lower mantle’s grain size evolution law is controlled by bridgmanite-ferropericlase grain growth. Our results suggest that mantle viscosity is primarily controlled by temperature, whereas grain size has a minor effect compared to the effect of temperature. We attribute two primary reasons for this: First, the bridgmanite-ferropericlase growth is very slow in the lower mantle and the grain size variation is too small to significantly alter the mantle viscosity. Secondly, if grains grow too fast, thus the mantle deforms in the dislocation creep regime, making viscosity grain size-independent. To establish the robustness of this finding we vary several other model parameters, such as surface yield strength, phase transition grain size reset, different transitional stresses for creep mechanisms, pressure dependence on grain growth, and different grain damage parameters. For all our models, we consistently find that grain size has a very limited effect on controlling lower mantle viscosity in the present-day Earth. However, large grain size may have affected the lower mantle viscosity in the early Earth as larger grains of single phase bridgmanite could increase the viscosity of the early mantle delaying the onset of global convection.

Correlation between Electrochemical Relaxations and Morphologies of Conducting Polymer Dendrites

Conducting Polymer Dendrites (CPD) can engrave sophisticated patterns of electrical interconnects in their morphology with low-voltage spikes and few resources: they may unlock in operando manufacturing functionalities for electronics using metamorphism conjointly with electron transport as part of the information processing. The relationship between structure and information transport remains unclear and hinders the exploitation of the versatility of their morphologies to store and process electrodynamic information. This study details the evolution of CPD's circuit parameters with their growth and shape. Through electrochemical impedance spectroscopy, multiple distributions of relaxation times are evidenced and evolve specifically upon growth. Correlations are established between dispersive capacitances of dendritic morphologies and growth duration, independently from exogenous physical variables: distance, evaporation or aging. Deviation of the anomalous capacitance from the conventional Debye dielectric relaxation can be programmed, as the growth controls the dispersion coefficient of the dendrite's constant-phase elements relaxation. These results suggest that the fading-memory time window of pseudo-capacitive interconnects can practically be conditioned using CPD morphogenesis as an in materio learning mechanism. This study confirms the perspective of using electrochemistry for unconventional electronics, engraving information in the physics of conducting polymer objects, and storing information in their morphology, accessible by impedance spectral analysis.

Experimental Study on Mechanical Properties of Cured Sand Combined with Plant-Based Bio-cement (PBBC) and Organic Materials.

Bio-cement is a green and energy-saving building material, which has received wide attention in the field of ecological environment and geotechnical engineering in recent years. The aim of this study is to investigate the improvement effect of plant-based bio-cement (PBBC) in synergistic treatment of sand with organic materials, to highlight the effective use of tap water in PBBC, and to analyze the crack evolution pattern during the damage of specimens by using image processing techniques. The results showed that tap water can be used as a solvent for PBBC instead of deionized water. The characteristic trend of urease solutions prepared at different temperature environments was obvious, and the activity value of urease solution with low concentration is positively correlated with the ambient temperature, although the activity value is not high, it is not easy to inactivate. The incorporation of organic materials increased the peak stress up to 1809.30kPa compared to the specimens modified only by PBBC. The damage of the specimens under uniaxial compression consisted of four stages: compaction, elastic deformation, pre-peak brittle damage and post-peak macroscopic damage. The corresponding crack evolution is the interpenetration of small-sized cracks into large-sized main cracks. The large-sized main cracks transform into penetration cracks before damage, and the small-sized cracks are distributed around the penetration cracks. The crack evolution parameters obtained by MATLAB processing are positively correlated with the strain.

Microstructure evolution modeling of Ti6Al4V alloy during cutting using the Particle Finite Element Method and homogeneous field distributions

This paper aims to explore the evolution of microstructural parameters induced during the cutting of Ti6Al4V alloy (TC4). The microstructure characteristics of the workpiece material is directly tied to its mechanical response during machining. During TC4 cutting, microstructure evolution is observed as a result of severe plastic deformations. The characterization of this phenomenon has significant interest from both academia and industry. In this work we present a developed modeling technique which combines the Particle Finite Element Method (PFEM) with incremental homogeneous field distributions. First, the PFEM is extended to perform a thermo-mechanical analysis capable of capturing the material responses of TC4 during orthogonal cutting. To generate serrated chips, an appropriate strain softening-based constitutive plasticity model i.e., TANH (Hyperbolic TANgent) is utilized. The PFEM’s validity is checked through comparison with available experimental results in terms of chip shapes and cutting forces. Second, the evolution of microstructural parameters such as dislocation density, vacancy concentration, dynamic recrystallization (DRx) grain size, and hardness is incrementally developed and incorporated into the PFEM using internal state variables as homogeneous field distributions. The Johnson–Mehl–Avrami–Kolmogorov (JMAK) model and Hall-Petch equation are applied for predicting grain size and hardness, respectively. The parameters of the corresponding models are modified for TC4 to accurately capture their alterations. Lastly, the predicted results of the microstructure evolution in serrated chips and machined surfaces, including average grain size and hardness, are compared with experiments, demonstrating good agreement. This implies that the PFEM combined with microscale schemes can reliably simulate the machining process of the TC4.

Study of the Density Parameters of the Dark Energy and the Cosmological Constant in the context of Brans-Dicke Theory

Abstract The discovery of supernova projects at the end of the 20 th century altered the theory of current cosmology and sparked the hunt for dark energy and dark matter. The time evolution of the density parameter is examined here by considering a test function. Using the Brans-Dicke frame work, the calculations are advanced. The density parameter of dark energy (Ω D ) and matter (Ω m ) are connected by mathematical descriptions and found to produce a unit value when Ω D and Ω m are in fraction. As the calculations are built on the structure of the scale factor, this present article is attempt to describe the framework in terms of scale factor (a) as well. The results coming from the test function model show nice resemblance with known observations. The use of Brans-Dicke theory makes provision for in detail study of Ω D and Ω m .

Soot particle morphology and polycyclic aromatic hydrocarbons formation molecular dynamics during diffusion combustion of three pentanol biofuels

Soot particles constitute a major pollutant in engine diffusion combustion, posing a serious threat to human health and the atmospheric environment. The employment of carbon-neutral biofuel, pentanol, in engines contributes to reducing soot emissions; however, its effectiveness is contingent upon the position of the OH functional group. This work investigated the soot morphology and microstructural parameters evolution of three pentanol isomers, and explored the influence mechanism of OH functional group positional isomerism on the entire process of PAHs formation at the atomic level. The results showed that the peak of primary particle size and soot volume fraction in pentanol flames showed a trend of 2-pentanol>3-pentanol>1-pentanol, and the initial formation time of soot in 1-pentanol flame is the latest, and the particle aggregate size is the smallest. The entire process of pentanol isomers soot formation can be divided into four stages: fuel pyrolysis forming initial ring, PAHs growing into initial soot, soot chain growth and structural evolution, soot morphology transformation and maturation. Among the three isomers, 2-pentanol has the fastest initial ring formation rate, the highest peak C-number in the largest molecule, and ultimately forms a more mature fullerene-like structure. 1-pentanol has the slowest initial ring formation rate, the lowest peak C-number in the largest molecule, ultimately forms a lower maturity layered structure. In terms of reaction pathways, H-atom abstraction and dehydroxylation reactions jointly dominate the initial decomposition pathway in 1-pentanol combustion, while in 2-pentanol, dehydroxylation becomes the main initial decomposition pathway due to the high stability of H atoms on β‑carbon. The dehydroxylation reaction tends to generate olefins, promoting the generation of C1-C4 hydrocarbon. The oxygen atom bonded on the α‑carbon site exhibits a stronger carbon fixation ability, and C1-C4 hydrocarbons are more inclined to participate in oxidation to form CO rather than promote the soot production.