Nonlinear Increase Research Articles

Unveiling photon-driven nonlinear evaporation via liquid drop interferometry.

We investigated photomolecular-induced evaporation, wherein photons cleave off water clusters near water-vapor interfaces, bypassing the typical thermal evaporation process. However, thermal-induced evaporation is the main bottleneck to precisely identify photon-induced evaporation. Liquid drop interferometry (LDI) resolved this bottleneck, utilizing evaporating water drops as an active element. Interestingly, we first observed near-total internal reflection, a nonlinear increase in evaporation attributed to photomolecular-induced evaporation, which had never been studied before, to the best of our knowledge. Furthermore, by generating a standing wave on a partially metallic polished prism, we uncovered an unexpected enhancement in evaporation coinciding with the wave reaching its maxima at the air-water (AW) interface, validating that photomolecular-induced evaporation is a surface phenomenon. Significantly, our noninvasive measurements have identified transient deformation height as a key indicator of photon-induced cluster breaking and increased evaporation, thus significantly advancing our understanding of photomolecular effects on water droplet evaporation.

Nonlinear wave propagation in homogenized strain gradient 1D and 2D lattice materials: Applications to hexagonal and triangular networks

AbstractThis work aims to analyze the propagation of fully nonlinear waves, encompassing shear, extension, and bending deformation modes, within homogenized periodic nonlinear hexagonal and triangular networks, successively considering 1D and 2D situations. The wave analysis is conducted from the expression of the effective strain energy density of periodic hexagonal and triangular lattices in the nonlinear regime by a continualization of the discrete lattice equations, considering all forms of energy. We incorporate strain gradient effects into the continuous model to account for the wave‐dispersive nature. The resulting second‐gradient nonlinear continuum exhibits subsonic and supersonic propagation modes. We first examine in a 1D situation the dynamical response of the hexagonal and triangular lattices, considering varying levels of nonlinearity quantified by a single scalar valued parameter. We further evaluate the impact of a fully nonlinear analysis compared to an analysis solely based on the shear energy, regarding both supersonic and subsonic modes. The nonlinear wave propagation analysis is then extended to a 2D situation for the same two lattices. It is shown that the longitudinal mode exhibits a higher frequency at a low degree of nonlinearity; however, as the degree of nonlinearity increases, the shear mode surpasses the longitudinal mode in terms of frequency. As the wavenumber increases, the nonlinearity has a lesser impact on the frequency behavior, and the phase velocity is more influenced by other factors, such as the second gradient contributions of the effective constitutive law. Such a behavior indicates a transition from a highly nonlinear behavior at lower wave numbers to a more linear behavior at higher wave numbers.

Minimum cutting thickness prediction model for micro-milling machining and experimental Study of FeCoNiCrMn high-entropy alloy machining

FeCoNiCrMn high entropy alloy has excellent properties such as high hardness, high strength and high wear resistance, which has a broad application prospect in aerospace, military and other fields. As an emerging difficult-to-machine material, the minimum cutting thickness determines the highest machining accuracy of micro-milling. In order to improve the micro-milling quality of FeCoNiCrMn high-entropy alloy, a minimum cutting thickness prediction model based on the effective front angle of the tool is established according to the analysis of micro-milling force model. Through the FeCoNiCrMn high-entropy alloy micro-milling processing experiments, the milling force parameters are calculated by substituting them into the prediction model, and the minimum cutting thickness value of FeCoNiCrMn high-entropy alloy is 1.367 μm when the flank radius of the milling cutter is 5 μm.When the feed rate of each tooth is in the range of 1 μm–1.5 μm, the severe size effect and the ploughing effect lead to the specific cutting energy nonlinearly increase, and the cutting force and surface roughness increase sharply with large fluctuations. From this, the range of the minimum cutting thickness of the high-entropy alloy was judged to be between 1 μm and 1.5 μm, and the accuracy of this prediction model was verified.

Liquid-to-gas transfer of sodium in a liquid cathode glow discharge

Plasma-liquid interactions have been extensively studied with a focus on the transport of reactive species from the plasma to the liquid phase and their induced liquid phase chemistry and resulting applications. While solute transfer from the liquid to the gas phase in plasmas has been widely used in analytical chemistry, the underlying processes remain relatively unexplored. We report spatially and temporally resolved absolute density measurements of sodium in a plasma with a NaCl solution cathode using two-photon absorption laser induced fluorescence (TaLIF). The observed non-linear increase in sodium density with solution conductivity is shown to correlate with droplet generation as visualized by Mie scattering. The findings are explained by droplet generation by electrospray induced by Taylor cone formation as underpinning mechanism for the introduction of sodium in the plasma. An analytical sheath model combined with a scaling law shows an increase in electric field force with solution conductivity that is consistent with the observed non-linear increase in sodium density in the plasma with solution conductivity.

Effects of dietary tryptophan levels on growth performance, serotonin metabolism, brain 5-HT and cannibalism activities in tiger puffer, Takifugu rubripes fingerlings

Essential amino acid (EAA) requirements of aquaculture fish species can be used as a guideline for commercial feed formulation. Several EAA requirements have been quantified in tiger puffer (Takifugu rubripes). However, as the third limiting amino acid (AA) of many plant protein sources, tryptophan requirement of this species has yet to be quantified. This study was conducted to determine dietary tryptophan requirement of tiger puffer, and investigate the effect of dietary tryptophan supplementation on the cannibalism, brain serotonin (5-hydroxytryptpamine, 5-HT) metabolism and serum cortisol levels. Six experimental diets were prepared using fish meal, gelatin and corn protein concentrate as intact protein, and then supplemented with crystalline AA premix. The analyzed tryptophan levels in the experimental diets were 3.5, 4.1, 4.5, 5.5, 7.0 and 11.8 g/kg of dry diet. Experimental diets were randomly fed in triplicate to tiger puffer (initial average weight of 17.5 g) for 58 days. The weight gain (WG), feed conversion ratio (FCR) and protein efficiency ratio (PER) were significantly affected by dietary tryptophan, and the break points were observed at 5.07, 4.82 and 4.99 g/kg of dry diet, respectively. Compared to the basal diet, the cannibalism (the rate of bite mark appearance) was significantly lower and survival rate was significantly higher when fish were given diets containing 7.0 and 11.8 g/kg tryptophan. The concentrations of free tryptophan and phenylalanine in the brain exhibited a nonlinear increase in response to the incremental levels of dietary tryptophan. Brain 5-HT concentration was significantly affected by dietary tryptophan levels, but did not show a significant dose-dependent response. The expression of genes related to 5-HT metabolism (tph1a, ddc and aldh) and serotonin reuptake (sert) in the brain varied significantly and exhibited a nonlinear relationship with the graded levels of dietary tryptophan. In addition, serum cortisol levels showed a decreasing trend till the 5.5 g/kg tryptophan inclusion level, at which point there appeared to be the lowest level. In conclusion, based on nonlinear regression analysis of the WG, FCR and PER, dietary tryptophan requirement of tiger puffer was determined to be range between 4.82 and 5.07 g/kg of dry diet (10.48–11.03 g/kg of dietary protein). Dietary tryptophan supplementation above requirement could mitigate cannibalism and improve the survival of tiger puffer, which may be attributed to regulating the synthesis and catabolism of 5-HT and its availability in the synaptic cleft, and subsequently the reduction of serum cortisol content.

The Impact of Temporal Light Modulation on Psychological Responses Assessed by the Stroboscopic Visibility Measure

ABSTRACT With the advent of LED lighting systems, short-term psychological responses to temporal light modulation (TLM) in offices have attracted considerable research attention in recent years. The stroboscopic visibility measure (SVM) is a leading metric for predicting the visibility of stroboscopic effects, one of visual perception effects of TLM. However, research is lacking to link TLM with potential psychological responses using the SVM metric. In this study, 10 participants joined in the experiments under 6 SVM levels (SVM: ~0.060; ~0.500; ~1.000; ~1.500; ~2.500; ~3.868) finishing tasks of subjective general rating, moving objects observation, sustained attention visual task, visual fatigue scale and PANAS (Positive and Negative Affect Scales). This study found that the SVM metric significantly evaluated the impact of TLM on psychological responses related to lighting ambiance and the moving objects observation. As expected, the stroboscopic visibility and motion dispersion scores increased with increasing SVM levels in the observation of rotating disc, and detectable stroboscopic effects were found to have negative effects on visual and work performances. However, the results of sustained attention visual task indicated that the SVM metric performed poorly in predicting the effects of TLM related to the eye saccades. High SVM levels were associated with negative experiences of lighting coziness, cognition performance and stroboscopic perception during moving objects observation. The scores were close to the expected at ~ 1.000 but exhibited a non-linearly increase with higher SVM levels. This study contributes valuable data to the ongoing discussions on setting limits for allowable modulation in practical lighting applications.

Gas separation in bimetallic Zn/Co-ZIF-62 glass membrane

Metal-organic framework (MOF) glasses, are attracting increasing attention in the gas separation field due to their component flexibility, ease of processing and porous structures. In this work, a series of bimetallic MOF glass membranes were synthesized and the impact of the metal node ratio (Co/Zn) on the gas separation performance of the membranes was investigated. It is found that the replacement of Zn nodes by Co in the ZIF-62 glass membrane leads to a nonlinear increase in the separation selectivity for [Formula: see text] and [Formula: see text]. Such a phenomenon corresponds to the mixed-metal node effect found in the MOF glass. Through the structural characterization results, we found that the different affinities of the central metal nodes towards gas molecules and the diversity in porosity of the Zn/Co-ZIF-62 membranes could be the two main reasons for the evolution of the gas separation properties in the ZIF-62 glass membranes. This work gives a new approach to developing MOF glass membranes with high-performance gas separation.

Nuclear quantum effect on the elasticity of ice VII under pressure: A path-integral molecular dynamics study

We investigate the effect of nuclear quantum effects (NQEs) of hydrogen atoms on the elasticity of ice VII at high pressure and ambient-temperature conditions using path-integral molecular dynamics (PIMD) calculations. We find that the NQEs of hydrogen contribute to the transition of ice VII from a static disordered structure to a dynamically disordered structure at pressures exceeding 40 GPa. This transition is characterized by a nonlinear increase in the elastic constants. A comparison of molecular dynamics, and PIMD calculations shows that NQEs increase the elastic constants of ice by about 20% at 70 GPa and 300 K. Published by the American Physical Society 2024

Noninvasive identification and therapeutic implications of supernormal left ventricular contractile phenotype

Left ventricular (LV) function is typically evaluated through LV ejection fraction (EF), a robust indicator of risk, showing a nonlinear increase in mortality rates below 40%. Conversely, excessively high EF values (> 65%) also correlate with elevated mortality, following a U-shaped curve, with its nadir observed between 50% and 65%. This underscores the necessity for improved identification of the hypercontractile phenotype. However, EF is not synonymous with LV contraction function, as it can fluctuate independently of contractility due to variations in afterload, preload, heart rate, and ventricular-arterial coupling. Assessing the contractile status of the LV requires more specific metrics, such as LV elastance (or contractile force) and global longitudinal strain. Current guidelines outline various parameters for a more precise characterization of LV contractility, yet further research is warranted for validation. The true hypercontractile phenotype is evident in cardiac pathologies such as hypertrophic cardiomyopathy, ischemia with angiographically normal coronary arteries, Tako-tsubo syndrome, heart failure with preserved EF, and may also stem from systemic disorders including anemia, hyperthyroidism, liver, kidney, or pulmonary diseases. The hypercontractile phenotype constitutes a distinctive hemodynamic substrate underlying clinical manifestations such as angina, dyspnea, or arrhythmias, presenting a target for intervention through beta-blockers or specific cardiac myosin inhibitors. While EF remains pivotal for clinical classification, risk stratification, and therapeutic decision-making, integrating it with other indices of LV function can enhance the characterization of the hypercontractile phenotype.

Comparison of time-motion, heart rate responses, and training load measurement in Brazilian jiu-jitsu heavyweight and lightweight fighters: a cross-sectional study

ABSTRACT This study compares technical-tactical and physiological parameters between lightweight and heavyweight male Brazilian Jiu-Jitsu (BJJ) fighters. We included 11 adult BJJ fighters (lightweight: age = 28 ± 7 years; body mass = 73 ± 2 kg; height = 1.72 ± 0.7 m; body mass index = 25 ± 2 kg/m2; heavyweight: age = 27 ± 3 years; body mass = 95 ± 6 kg; height = 1.87 ± 0.6 m; body mass index = 27 ± 2 kg/m2). Six participants were considered lightweight (71 to 77 kg) and five heavyweight divisions (88 to 101 kg). Initially, sample characteristics and a graded exercise test determined the physiological parameters. A simulated competition (10 minutes maximum) assessed technical-tactical characteristics, Heart Rate (HR), Rate of Perceived Exertion (RPE), TRaining IMPulse based on HR, session-RPE, and time at HR intensity zones (Z1, Z2, and Z3). A comparison test revealed that heavyweight athletes exhibited a higher height, body mass, total time in low-intensity efforts per block, number of standing combat blocks, and less time in high-intensity efforts per block and lower VO2MAX than lightweight (p < 0.05). The HR showed a nonlinear increase throughout each minute of the fights, with the heavyweight division demonstrating predominantly higher HR values. All fighters accumulated more time in training zone 3. The physiological and temporal differences between divisions suggest that BJJ training must be designed specifically for lightweight or heavyweight divisions.

Numerical investigation of the hydrodynamic properties of oscillating water column air chambers

Abstract The oceans occupy nearly 71% of the Earth’s surface area. The ocean is rich in energy, and wave energy is one of its important components. Therefore, the study of wave energy generation devices is an important issue. In this paper, we analyze the effect of the size of the air chamber structure on the OWC (oscillating water column) wave energy conversion device under the action of unidirectional regular waves. To analyze the performance of the OWC device under real sea conditions, the wave climate at Sanmenxia is used as the experimental parameter. The performance and characteristic response with the variation of incident wave height, air chamber width and front wall thickness, are analyzed. The results show that the incident wave height, air chamber width, and front wall draft have significant effects on the performance of OWC. With the increase of incident wave height, the wave nonlinear effect increases. As the air chamber width decreases, the horizontal surface inside the air chamber undulates smoothly and the standing wave phenomenon disappears.

A multistage exergy evaluation-cooperated liquid level optimization approach for multi-equipment evaporation process

The liquid level for the evaporator is a significant parameter related to production safety and evaporation efficiency in the evaporation process. However, the process nonlinearity and time-delay increase the difficulty of operating control. Hence, a multistage exergy evaluation-cooperated liquid level optimization approach for multi-equipment evaporation process is proposed in this paper. An exergy evaluation-paralleled system based on exergy analysis is constructed. In addition, interdependent knowledge between liquid level and key process parameters is mined. Moreover, a multistage liquid level optimization model is established with the goal of minimizing energy consumption and constrained by stable production operation and qualified product quality. Meanwhile, a concentration forecasting strategy with ensemble learning based on gradient boosting decision tree is introduced into the optimization model while considering the asynchronous sampling frequency. Through application verification and analysis, the proposed liquid level optimization model provides feasible operational guidance for actual production, achieving high-quality, efficient, and green production.

Enhancing shale gas recovery: An interdisciplinary power-law model of hydro-mechanical-fracture dynamics

This study explores the efficiency of using carbon dioxide (CO2) to extract shale gas, highlighting its potential to enhance extraction while mitigating environmental CO2 pollution. Given the intricate microstructure of shale, CO2 injection inevitably induces deformation within the shale reservoir's internal microstructure, thereby impacting gas displacement efficiency. The organic matter (kerogen) network and fracture network in shale, serving as primary spaces for gas adsorption and migration, exhibit complex microstructural characteristics. Thus, we developed a dynamic coupled hydro-mechanics permeability model for binary gas displacement, and three novel, interdisciplinary fractal power-law parameters are proposed to represent the distribution of shale fractures, considering the adsorption–desorption strength of the kerogen network. Numerical simulations analyzed the changes in gas seepage, diffusion, shale stress, permeability, and factors influencing displacement efficiency during the CO2–EGR (enhanced gas recovery) projects. Key findings include (1) CO2 injection leads to a nonlinear increase in the number of shale fracture networks, thereby enhancing the CH4 output efficiency. (2) Compared to traditional fractal theory, the proposed power-law model is applicable to a wider range of reservoir fracture distributions and effectively characterizes the density (by α), size (by r), and complexity (by n) of the fracture network during the CO2–EGR process. (3) Changes in the proposed interdisciplinary power-law parameters significantly alter CO2 and CH4 adsorption capacities and, in turn, significantly affects displacement efficiency and shale deformation. According to calculations, these parameters have the greatest impact on the CO2–EGR process, ranging from 16.3% to 68.1%.

Improvement of synaptic property of GeSe based CBRAM by engineering the deposition condition of switching matrix

A study of effect of deposition condition of germanium selenide (GeSe) switching layer to Conductive bridging random access memory (CBRAM) device property was conducted to enhance memory property and synaptic property. The devices deposited under the varied deposition conditions were analyzed by current distribution of each state (Low-resistance state [LRS], High-resistance state [HRS]), conduction mechanism analysis, chemical analysis, and synaptic analysis according to pulse conditions. When we deposited switching layer at lowest power (40 W), more Ag ions move to the switching matrix and make lower operation voltage. But there were some disadvantages, which were worst distribution and higher HRS current, less memory window, nonlinear and rapid increase of potentiation process. Conversely, although the device deposited at high voltage increased the operating voltage, but there are improvements, such as the highest memory window and improved linearity of potentiation. The best sample was conducted the synaptic property measurement, and the device successfully mimicked the biological synaptic property with the good linearity of potentiation and depression, spike-rate dependent plasticity (SRDP) and spike-timing dependent plasticity (STDP) properties.

High-Order Extended Kalman Filter for State Estimation of Nonlinear Systems

In general, the extended Kalman filter (EKF) has a wide range of applications, aiming to minimize symmetric loss function (mean square error) and improve the accuracy and efficiency of state estimation. As the nonlinear model complexity increases, rounding errors gradually amplify, leading to performance degradation. After multiple iterations, divergence may occur. The traditional extended Kalman filter cannot accurately estimate the nonlinear model, and these errors still have an impact on the accuracy. To improve the filtering performance of the extended Kalman filter (EKF), this paper proposes a new extended Kalman filter (REKF) method that utilizes the statistical properties of the rounding error to enhance the estimation accuracy. After establishing the state model and measurement model, the residual term is used to replace the higher-order term in the Taylor expansion, and the least squares method is applied to identify the residual term step by step. Then, the iterative process of updating the extended Kalman filter is carried out. Within the Kalman filter framework, a higher-order rounding error-based extended Kalman filter (REKF) is designed for the joint estimation of rounding error and random variables, and the solution method for the rounding error is considered for the multilevel approximation of the original function. Through numerical simulations on a general nonlinear model, the higher-order rounding error-based extended Kalman filter (REKF) achieves better estimation results than the extended Kalman filter (EKF) and improves the filtering accuracy by utilizing the higher-order rounding error information, which also proves the effectiveness of the proposed method.

Effects of Strain Rate on the GND Characteristics of Deformed Polycrystalline Pure Copper

Geometrically necessary dislocations (GNDs) play a pivotal role in polycrystalline plastic deformation, with their characteristics notably affected by strain rate and other factors, but the underlying mechanisms are not well understood yet. We investigate GND characteristics in pure copper polycrystals subjected to tensile deformation at varying strain rates (0.001 s−1, 800 s−1, 1500 s−1, 2500 s−1). EBSD analysis reveals a non-linear increase in global GND density with the strain rate rising, and a similar trend is also observed for local GND densities near the grain boundaries and that in the grain interiors. Furthermore, GND density decreases from the grain boundaries towards the grain interiors and this decline slows down at high strain rates. The origin of these trends is revealed by the connections between the GND characteristics and the behaviors of relevant microstructural components. The increase in grain boundary misorientations at higher strain rates promotes the increase of GND density near the grain boundaries. The denser distribution of dislocation cells, observed previously at high strain rates, is presumed to increase the GND density in the grain interiors and may also contribute to the slower decline in GND density near the grain boundaries. Additionally, grain refinement by higher strain rates also promotes the increase in total GND density. Further, the non-linear variation with respect to the strain rate, as well as the saturation at high strain rates, for grain boundary misorientations and grain sizes align well with the non-linear trend of GND density, consolidating the intimate connections between the characteristics of GNDs and the behaviors of these microstructure components.

Novel techniques to analyze dynamical properties of quantum chaos with peculiar evidence of hybrid systems confinement

Recent results demonstrate the dynamical peculiarities of the quantum chaos within the hybrid systems by chaotic parameters and probe the pattern formation under the influence of condensation. The complex dynamic behavior of the considered systems was determined with numerical simulation and presented an efficient technique that studied fractional systems comprising chaos-coherence fractions. The findings divulge the peculiar association between the coherence structure and the correlations at finite relative momenta. Thus the present study helps to explore the partially chaos hybrid systems in order to stimulate the experimental applications of nonlinear phenomena. The coherent-chaotic parameters can be measured by examining the chaos peculiarities that possess explicit relations with the condensations to demonstrate the environs of the physical systems. We investigate the influence of the multiplicities, chaos, momentum and temperature of the nonlinear system on the coherent-chaotic normalized correlations. The chaotic parameters are suppressed considerably with the coherence fraction and it appears numerically zero at maximum condensation and one at ideal chaos emissions. We procure that the meaningful parameters decrease significantly with the multiplicity of the nonlinear systems and increase with the momentum in the specified regimes. The identical multiplicity leads to contemplating the coherence and thus the normalized chaotic parameters within its spectacular influences exhibit significance worth contemplating in earnest. The findings underscore the significance of cogitating correlations in deciphering the nonlinear system characteristics and bestowing extraordinary perceptiveness into the convoluted essence of complex systems. The contemplated methodology can be applied to evaluating and analyzing the nonlinear systems and such an innovative approach computes the problems of celestial mechanics, heartbeats and chemical reactions in engineering and medical fields.

Dielectric response of metal-organic frameworks as a function of confined guest species investigated by molecular dynamics simulations.

When using metal-organic frameworks (MOFs) as electric field-dependent sensor devices, understanding their dielectric response is crucial as the orientation of polar groups is largely affected by confinement. To shed light on this at the molecular level, the response to a static field was computationally investigated for two structurally related MOFs, depending on their loading with guest molecules. The pillared-layer MOFs differ in their pillar moiety, with one bearing a rotatable permanent dipole moment and the other being non-polar. Two guest molecules with and without polarity, namely, methanol and methane, were considered. A comprehensive picture of the response of the guest molecules could be achieved with respect to both the amount and polarity of the confined species. For both MOFs, the dielectric response is very sensitive to the introduction of methanol, showing an anisotropic and non-linear increase in the system's relative permittivity expressed by a strongly increasing polarization response to external electric fields scaling with the number of confined methanol molecules. As expected, the effect of methane in the non-dipolar MOF is negligible, whereas subtle differences can be observed for the dipolar response of the MOF with rotatable dipolar linker groups. Taking advantage of these anisotropic and guest-molecule-specific confinement effects may open pathways for future sensing applications. Finally, methanol-induced global framework dynamics were observed in both MOFs.

Effect of doping and preparation parameter on AC conductivity and dielectric modulus formalism of Al doped DLC thin films

Here, we report the composite effect of aluminum doping on the dielectric response of Diamond-Like Carbon (DLC) thin films. In addition, the contribution from preparation parameters like acetylene flow rate is also considered to understand sample behavior. AC conductivity study shows the existence of a nonlinear increase of conductivity with frequency leading toward the Jump Relaxation Model (JRM). The transition frequency (ft) is observed, which increases with conductivity. The study reveals that dielectric response is influenced by space charge conductivity, prompting us to adopt the modified Debye law. Deviation from ideal Debye behavior is also confirmed in dielectric modulus analysis. The deviation is frequency-dependent, and a higher deviation is observed in the high-frequency region. Plotting of the Master curve shows the presence of different relaxation dynamics in different samples. A current-voltage (I-V) study of different samples is also undertaken, showing higher values (greater than unity) of the ideality factor.

Exercise as medicine! Physical activity mitigated the impact of the COVID-19 pandemic on depressive symptoms in adults with depression

We investigated the longitudinal association between physical activity (PA) and symptoms of depression and anxiety in people with depression during the COVID-19 pandemic. We used data from baseline (June 2020) to wave 3 (June 2021) of the PAMPA Cohort, an ambispective cohort with adults in south Brazil. The Hospital Anxiety and Depression Scale assessed depressive and anxiety symptoms in all waves. Participants reported frequency (minutes), type (aerobic, strength, combined), and place (out of home, at home) of physical activity at baseline. Generalized linear models were used to investigate the interaction between time and PA, adjusting for possible confounding variables. Subjective memory decline was assessed using multivariate Cox proportional hazard regression models to obtain adjusted hazard ratio (HR) and respective 95% confidence interval (CI). Participants (n = 424) with self-reported clinically diagnosed depression were included. We observed a non-linear increase trajectory of depression during the first year of the COVID-19 pandemic. PA was associated with a slower trajectory of depressive (slope: −1.89; 95%CI: −3.34, −0.43 points) but not anxiety (slope: −1.33; 95%CI: −2.93, 0.25 points) symptoms during the COVID-19 pandemic. Participants who continued physically active from pre-pandemic in wave 1 showed a lower risk of subjective memory decline during follow-up than those who persisted inactive in the same period (HR: 0.52; 95%CI: 0.30, 0.89). PA attenuated the impact of the COVID-19 pandemic on depressive symptoms in adults living with depression in south Brazil. Regularity of physical activity was associated with fewer depression and anxiety symptoms and a lower risk of subjective memory decline.