Memory Effect Research Articles

Astrocytic determinant of the fate of long-term memory.

While some vivid memories are unyielding and unforgettable, others fade with time. Astrocytes are recognized for their role in modulating the brain's environment and have recently been considered integral to the brain's information processing and memory formation. This suggests their potential roles in emotional perception and memory formation. In this study, we delve into the impact of amygdala astrocytes on fear behaviors and memory, employing astrocyte-specific optogenetic manipulations in mice. Our findings reveal that astrocytic photoactivation with channelrhodopsin-2 (ChR2) provokes aversive behavioral responses, while archaerhodopsin-T (ArchT) photoactivation diminishes fear perception. ChR2 photoactivation amplifies fear perception and fear memory encoding but obstructs its consolidation. On the other hand, ArchT photoactivation inhibits memory formation during intense aversive stimuli, possibly due to weakened fear perception. However, it prevents the decay of remote fear memory over three weeks. Crucially, these memory effects were observed when optogenetic manipulations coincided with the aversive experience, indicating a deterministic role of astrocytic states at the exact moment of fear experiences in shaping long-term memory. This research underscores the significant and multifaceted role of astrocytes in emotional perception, fear memory formation, and modulation, suggesting a sophisticated astrocyte-neuron communication mechanism underlying basic emotional state transitions of information processing in the brain.

Optimization of Dynamic Characteristics of Rubber-Based SMA Composite Dampers Using Multi-Body Dynamics and Response Surface Methodology

The suspension system of a commercial vehicle cab plays a crucial role in enhancing ride comfort by mitigating vibrations. However, conventional rubber suspension systems have relatively fixed stiffness and damping properties, rendering them inflexible to load variations and resulting in suboptimal ride comfort under extreme road conditions. Shape memory alloys (SMAs) represent an innovative class of intelligent materials characterized by superelasticity, shape memory effects, and high damping properties. Recent advancements in materials science and engineering technology have focused on rubber-based SMA composite dampers due to their adjustable stiffness and damping through temperature or strain rate. This paper investigates how various structural parameters affect the stiffness and damping characteristics of sleeve-type rubber-based SMA composite vibration dampers. We developed a six-degree-of-freedom vibration differential equation and an Adams multi-body dynamics model for the rubber-based SMA suspension system in commercial vehicle cabins. We validated the model’s reliability through theoretical analysis and simulation comparisons. To achieve a 45% increase in stiffness and a 64.5% increase in damping, we optimized the suspension system’s z-axis stiffness and damping parameters under different operating conditions. This optimization aimed to minimize the z-axis vibration acceleration at the driver’s seat. We employed response surface methodology to design the composite shock absorber structure and then conducted a comparative analysis of the vibration reduction performance of the optimized front and rear suspension systems. This study provides significant theoretical foundations and practical guidelines for enhancing the performance of commercial vehicle cab suspension systems.

Bacteria-Mediated Tumor-Targeting Delivery of Multienzyme-Mimicking Covalent Organic Frameworks Promoting Pyroptosis for Combinatorial Sono-Catalytic Immunotherapy.

Pyroptosis, an inflammatory cell death, has attracted great attention for potentiating a strong immune response against tumor cells. However, developing powerful pyroptosis inducers and then activating specific pyroptosis still remains challenging. Herein, a PEG-CuP-COF@∆St nanosystem is rationally designed, consisting of PEG-CuP-COF nanozyme pyroptosis inducers and tumor-targeting bacteria of the Salmonella Typhimurium strain VNP20009 (ΔSt), with an affinity for the tumor hypoxic microenvironment. The PEG-CuP-COF nanozymes possessed excellent sonodynamic performance and multienzyme-mimicking activities to generate reactive oxygen species (ROS) and then induce potent pyroptosis. The superoxide dismutase- and peroxidase-mimicking activities of PEG-CuP-COF catalytically produced hydrogen peroxide (H2O2) and hydroxyl radicals (•OH) which have important value in triggering acute inflammatory responses and pyroptosis. Moreover, PEG-CuP-COF showed outstanding glutathione peroxidase-mimicking activities, impairing the antioxidant defense in tumor cells and enhancing sonodynamic efficiency by making them more vulnerable to ROS-induced damage. During in vivo studies, PEG-CuP-COF@∆St nanosystem with its self-driven property exhibited impressive tumor-targeting capability and activated Caspase-3/gasdermin E-dependent pyroptosis to inhibit tumor growth. More importantly, it induced a powerful immune memory effect to prevent bone metastasis. In summary, this study introduces an innovative approach for combinatorial sono-catalytic immunotherapy using bacteria-mediated tumor-targeting delivery of nanozymes as specific pyroptosis inducers.

Asian Rainbow Option Pricing Problem Based on Uncertain Fractional Differential Equations

Option pricing is a core issue in option trading, which directly affects investors’ trading decisions and risk management. With the growing maturity of uncertainty theory, the research on option pricing problems based upon uncertainty theory has been gradually deepened. However, the volatility of stock price is not only related to the price at the current moment, but also related to all the previous stock price changes. Uncertain fractional differential equations can well portray the memory and history dependence of financial markets. Its nonlocal nature can more accurately describe the long-term memory effect and the phenomenon of spiky fat tails of stock market fluctuations. Thus, this paper mainly explores the pricing of Asian rainbow option in uncertain financial environments, where the underlying asset price is viewed as uncertain fractional processes. First, two models are presented for discussing the price of Asian rainbow option in two-asset cases, respectively. Then the pricing problems of different types of Asian rainbow options under [Formula: see text]-assets case are further discussed. Finally, empirical analysis is conducted on the proposed models with real stock data to verify the validity of the pricing formulas.

In Situ Optical Observation of Lithium Dendrite Pattern in Solid Polymer Electrolytes.

Solid polymer electrolytes (SPEs) have been treated as a viable solution to build high-performance solid-state lithium metal batteries (SSLMBs) at the industrial level, bypassing the safety and energy density dilemmas experienced by today's lithium-ion battery technology. To promote a wider application of SPEs-based SSLMBs, the chemical and electrochemical characteristics of lithium metal (Li°) electrode in SPEs have to be clearly elucidated. In this work, the morphological evolution of Li° electrode in the SPEs-based SSLMBs is comprehensively investigated, via a customized electrochemical cell allowing optical microscopic analyses. The results demonstrate that differing from inorganic solid electrolytes, the elastic feature of SPEs eliminates the "memory effect" of the dendrite formation, in which the previously formed dendrites can be dissolved and the resulting space can be simultaneously occupied by electrolyte components, instead of leaving for a second-round growth of Li° dendrites. Furthermore, the largely increased electronic conductivities of the as-formed interphases between Li° electrode and SPEs are found to be responsible for the notoriously soft short-circuit behavior observed during cycling. These findings bring a fresh understanding of the formation and evolution of lithium dendrites in SPE-based cells, which are vital for improving the long-term stability of SSLMBs and other related high-energy battery systems.

Memory in the Burst Occurrence of Repeating Fast Radio Bursts

Understanding the nature of repeating fast radio bursts (FRBs) is crucial for probing their underlying physics. In this work, we analyze the waiting time statistics between bursts of three repeating FRBs from four data sets. We find a universally pronounced dependency of the waiting times on the previous time interval (denoted as λ 0). We observe a temporal clustering, where short waiting times tend to be followed by short ones and long by long, comparative to their mean value. This memory dependency is manifested in the conditional mean waiting time as well as in the conditional mean residual time to the next burst, both of which increase in direct proportion to λ 0. Consequently, the likelihood of experiencing a subsequent FRB burst within a given time window after the preceding burst is generally influenced by the burst history. We reveal, for the first time, that these memory effects are present in the scale-invariant preconditioned waiting time distribution. We show that the memory effect provides a unified description of waiting times that may account for both the repeating FRBs and the apparently nonrepeating FRBs (i.e., those only observed one time). These results shed new light on the mechanism of FRBs.

Relaxation and rheology in beam-vibrated granular system

The yielding transition in dense granular matter under vibrated beams, despite its significance for animal and robotic locomotion on granular surfaces and underground structural engineering, remains underexplored. In this study, we systematically modulate the frequency and amplitude of beam vibrations through experiments and simulations to investigate the granular relaxation dynamics. We uncover dual yielding behaviors: gradual, ductile transitions in the time domain, where the system smoothly stabilizes, and abrupt, brittle transitions in the frequency domain, characterized by sharp shifts between metastable states and pronounced hysteresis, highlighting the dynamic consistency between the behavior of the beam and the granular materials. Through detailed analysis of the mesostructural evolution, encompassing particle motion, and mechanical stability, we unveil the root of the hysteresis as stemming from anomalous diffusion driven by memory effects, where the system's response is influenced by its stress history. These findings lead to the development of a nonmonotonic constitutive law that captures the unique frequency-dependent coupling between the beam and granular material. Our findings pave the way for advanced theoretical models in this domain, offering profound insights into the nuanced behaviors of vibrated granular systems.

Fractional-Order Mathematical Modeling and Stability Analysis of Tumor-Immune System Relation Including Chemotherapy Drug Effect

Cancer diseases rank second in global mortality rates. Among the prevalent approaches for treating tumors, chemotherapy stands out as a prominent method capable of reducing tumor size and managing the advancement of cancer ailments. To gain deeper insights into the intricacies of chemotherapy mechanisms, we devised a Fractional-order mathematical model, depicting tumor growth in the presence of chemotherapy. This comprehensive model encompasses both the immune system's response and the effects of drug therapy. To demonstrate that the system is biologically meaningful, we examined the existence and uniqueness of solutions and proved the positivity and boundedness of solutions. We characterize the dynamics properties of this differential equation model by finding the equilibrium points and exploring the stability conditions in a range of model parameters. In addition, we have performed numerical simulations considering different parameter values. Furthermore, to demonstrate the memory effect of the fractional derivative, we have simulated the dynamic behavior of the system for different orders of fractional derivatives. So, we have concluded that the memory effect occurs as the α decreases from 1 and the chemotherapy drug is quite effective on the populations. We hope that this work will contribute to helping medical scientists take the necessary measures during the screening process and treatment.

Hygrothermoelastic analysis of the nano-circular plate with memory effect

In hygrothermal environments, the coupling effects of temperature and moisture substantially impact deflection and stresses play a significant role. This study presents a coupled hygrothermoelastic model with non-Fourier and non-Fick effects established by introducing relaxation times or phase lags of heat and moisture flux accompanied by memory-dependent derivatives. The boundary value problem is formulated by considering a thin circular plate as an exemplary example, where the perimetric edge is clamped. The upper and lower edges of the plate is subjected to zero temperature, whereas the curved surface is exposed to hygrothermal shock. The closed-form solution of temperature and moisture distribution is obtained via the integral transform approach. The Fourier series expansion approach is used to calculate the numerical Laplace inversion. The effects of both heat and moisture flux relaxation times on the thermal deflection/stresses of the plate are analyzed and illustrated graphically.

In-situ constructing AlTiZn/CN heterojunction via memory effect for effective degradation of naphthalene under UV irradiation

In-situ constructing AlTiZn/CN heterojunction via memory effect for effective degradation of naphthalene under UV irradiation

A Comparative Analysis of Fractal and Fractionalized Thermal Non-Equilibrium Model for Chaotic Convection Saturated by Porous Medium

The convective heat transfer is one of the most important mechanism of heat transference for controlling the chaotic characteristics in porous media. A comparative study of thermal non-equilibrium model is proposed for fractal porous under the consideration of chaotic convection. A novel chaos control is focused between fractal porous and fractional porous by means of newly proposed differential and integral techniques. The sensitivity analysis for chaos expansion and uncertainty quantification for the flow in heterogeneous media have been perceived to the problem of chaotic convection through numerical simulations. In order to approximate the propagation of chaos, two types of simulations have been carried out in terms of chaotic attractors through fractal and fractional approaches. For examining a variety of chaos under the numerical simulations in which fractal domain is varied and fractional domain is fixed, fractal domain is fixed and fractional domain is varied, and both fractal as well as fractional domain are varied. Finally, it is observed that the fractional and fractal memory effects have caused by interactions between uncertain parameters and disclosed the microstructures on the permeability of porous media.

Realization of the shape memory effect in a composite material PLA/Diopside with different supramolecular structures

This study explores the realization of the shape memory effect (SME) in composite materials composed of polylactide (PLA) filled with diopside particles exhibiting varied supramolecular structures, such as spherulites and amorphous lamellar structures. We investigated the influence of diopside filler on the thermomechanical properties and shape recovery behavior of PLA-based composites. Different supramolecular structures of PLA were achieved through controlled crystallization processes. Comprehensive characterization techniques, including differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and dynamic mechanical analysis (DMA), were employed to elucidate the structure-property relationships. The results indicate that the diopside enhances the SME of PLA composites, with the degree of improvement being dependent on the specific supramolecular structure of the polymer matrix. Our findings provide insights into the design of advanced SMPs with tailored properties for potential applications in medicine.

Nitinol Reactive Oxygen Assist Gas Laser Micromachining: Demystifying the Implications Imposed Upon Pseudoelasticity and the Shape Memory Effect for Nickel-Titanium Alloys

Nitinol Reactive Oxygen Assist Gas Laser Micromachining: Demystifying the Implications Imposed Upon Pseudoelasticity and the Shape Memory Effect for Nickel-Titanium Alloys

A multifunctional partially bio-based epoxy resin by renewable chitosan as reaction raw material: shape memory effect, bonding property, excellent degradability, and toughening performance

A multifunctional partially bio-based epoxy resin by renewable chitosan as reaction raw material: shape memory effect, bonding property, excellent degradability, and toughening performance

Solar-driven induced photoelectron remember effect involved in core–shell NiCo2S4@Ni3V2O8 composite electrode with superior electrochemical energy storage for asymmetric supercapacitor

Photo-assisted supercapacitor systems offer a compelling approach to effectively harnessing both solar and electrical energy. In this study, the core–shell heterostructure NiCo2S4@Ni3V2O8 (NCS@NVO) was successfully synthesized for the development of photosensitive supercapacitor electrodes. NCS@NVO demonstrated a pronounced photoelectron memory effect under illumination, attributed to the solar-driven contributions of both NCS and NVO, as photon absorption facilitated electron-hole pair separation and transport. Compared to the specific capacitance in the dark (2292F g−1 at 1 A g−1), the capacitance of the NCS@NVO composite electrode increased dramatically to 3025F g−1 when exposed to light. Moreover, the capacitance retention rate remained remarkably high at 99.83 % after 10,000 cycles at 20 A g−1. In addition, the NCS@NVO hybrid supercapacitor achieved an outstanding energy density of 63.56 W h kg−1 under illumination, alongside a power density of 789.84 W kg−1. This study thoroughly investigated the solar-induced photoelectron memory effect in the NCS@NVO composite electrode for asymmetric supercapacitors, paving the way for the design of high-performance photosensitive nano-electrodes in advanced electrochemical energy storage applications.

Corrosion-oriented self-healing coating based on ZnMg MOF for efficient corrosion protection of aluminum alloy via in-situ LDH film formation

A corrosion-oriented self-healing coating system relying on metal–organic framework (MOF) based nanofiller is designed for aluminum alloy protection. The nanofiller is comprise of ZnMg MOF nanoparticle as a framework, salicylaldoxime corrosion inhibitors inside the MOF, and a polydopamine layer on the MOF surface. The Al3+ ions generated from the aluminum alloy substrate at the damaged coating area can etch the nanofiller, causing the collapse of the nanofiller and releasing the corrosion inhibitors to suppress the corrosion process in time. Subsequently, Zn2+ and Mg2+ ions from the nanofiller co-precipitate with Al3+ to form a dense AlZnMg layered double hydroxide (LDH) film, which provides further protection performance at the exposed alloy surface. Electrochemical impedance spectroscopy results demonstrate that the intact MOF@S/P coating exhibits a remarkable corrosion resistance property. For the damaged coating, the self-healing performance originated from the formation of LDH layer and the release of corrosion inhibitors gradually took effect, with the |Z|0.01Hz value increasing 2.27 times within 14 days. Moreover, under near-infrared irradiation, the photothermal effect of polydopamine will accelerate the release of corrosion inhibitor, the formation of LDH film, as well as the shape memory effect of coating defect for an efficient recovery of the corrosion resistance property. This novel coating system enables a corrosion-driven and location-specific repair with in-situ deposition of both an inhibitor film and an LDH film. As the first work to fully utilize and consume nanofillers on demand, this approach prevents inadequate use of healing agents, addressing a significant challenge in corrosion-driven self-healing coatings. The self-healing mechanism ensures target-oriented corrosion protection that makes the most efficient use of the healing substances.

Chaotic dynamics in a class of generalized memristive maps.

The memory effects of the memristors in nonlinear systems make the systems generate complicated dynamics, which inspires the development of the applications of memristors. In this article, the model of the discrete memristive systems with the generalized Ohm's law is introduced, where the classical Ohm's law is a linear relationship between voltage and current, and a generalized Ohm's law is a nonlinear relationship. To illustrate the rich dynamics of this model, the complicated dynamical behavior of three types of maps with three types of discrete memristances is investigated, where a cubic function representing a kind of generalized Ohm's law is used, and this cubic function is a simplified characteristic of the famous tunnel diode. The existence of attractors with one or two positive Lyapunov exponents (corresponding to chaotic or hyperchaotic dynamics) is obtained, and the coexistence of (infinitely) many attractors is observable. A hardware device is constructed to implement these maps and the analog voltage signals are experimentally acquired.

Engineering PLA-MXene nanocomposite with balanced mechanical properties for enhanced shape memory effect

AbstractPoly(lactic acid) (PLA) as shape memory material has gained attention due to its biocompatibility, biodegradability, and ease of processing by 3D printing. PLA’s environmentally friendly nature makes it an attractive candidate for sustainable and recyclable shape memory applications. However, PLA’s slow shape recovery rate and low shape fixation percentage hinder its applicability as shape memory material. In the present study, we report MXene-modified PLA (PLA/Mx) nanocomposite with enhanced shape memory effect. Solution processing methods mediated the loading of the MXene in the PLA matrix. Different samples were prepared by varying the weight% of the MXene in the PLA matrix. The structure and morphology of samples were analyzed by XRD and TEM characterization. Thermogravimetric analysis was performed to measure the thermal stability of the composite. Compared with pure PLA, with MXene loading, the PLA/Mx composites show an increase in thermal. The shape recovery study on PLA/Mx samples used temperature as an external stimulus. The PLA/Mx composite exhibited a significantly improved shape memory effect than the PLA alone. The study exhibits that a shape memory effect can be improved by tuning the MXene additive loading in the PLA matrix. The material shape recovery effect was validated by fabricating the spiral structure. The fast shape recovery time 3s and shape fixation/recovery of > 95% was observed for 1 wt% of PLA/Mx. The PLA/Mx composite is expected to contribute significantly to implementing innovative shape memory applications, particularly in the biomedical field for sutures, controlled drug release, and minimally invasive devices.

Study of atomic diffusion behavior in diffusion welding of NiTi alloy - based on molecular dynamics

NiTi alloy with nearly equiatomic ratios of Ni and Ti, has a unique shape memory effect and biocompatibility. Atomic diffusion is a determinant factor for the diffusion welding of NiTi alloys joining. In general, the atomic diffusion may be mediated by the temperature, time and pressure and so on. Despite the importance of technology, Ni and Ti atoms’ diffusion mechanism, however, still remains un-elucidated. Few works have investigated the movement rules of atoms from the atomic scale. Molecular dynamics simulations of diffusion welding were performed for 200-800ps to investigate the diffusion process of the NiTi alloy composite plate at temperatures of 1000, 1100, 1200, and 1300K. The results show that the holding temperature had the greatest effect on diffusion, with pressure having the least effect. The diffusion coefficients of NiTi, Ni, and Ti were calculated at temperatures of 1000, 1100, 1200, and 1300K, respectively. The diffusion degree of Ni atoms was higher than that of Ti atoms. The diffusion coefficients of Ni and Ti atoms satisfied the Arrhenius equation, and the diffusion activation energy of Ni atoms was lower than that of Ti atoms. Furthermore, this study demonstrates at the atomic scale that the growth of the diffusion layer at high temperatures follows the parabolic growth kinetics law.

Exploring fonts as retrieval cues in text-based learning

A growing body of research focuses on optimizing retrieval processes to help learners recall information from memory. The context-dependent memory effect suggests that information retrieval is more effective when the retrieval context matches the learning context. This phenomenon has been investigated in a variety of study materials and samples. However, there is a research gap in which this effect has not yet been investigated with font. Therefore, the font may act as a contextual retrieval cue, making it easier for learners to recall the presented information. In this context, the present experiment assumes that a match between the font used during learning (encoding phase) and that used during testing (decoding phase) improves retrieval processes and thus learning performance, while a mismatch has a negative effect. To test this assumption, 130 university students were randomly assigned to one condition of a two (font of learning texts: Haettenschweiler vs. Times New Roman) × two (font of learning questions: Haettenschweiler vs. Times New Roman) between-subjects design. Contrary to expectations, using the same font for encoding and decoding did not improve learning performance. Furthermore, learners did not report higher levels of mental effort when they had to work on learning questions presented in the same font as the learning texts. Although the font of the learning text is the most salient feature, it does not seem to serve as an effective retrieval cue in text-based learning.