Excitation Mechanism Research Articles

The secondary visual cortex mediated the enhancement of associative learning on methamphetamine self-administration behaviors.

Methamphetamine addiction is a persistent and intractable pathological learning and memory, whereas no approved therapeutics is available. However, few attentions have been paid to how associative learning participates in the formation of intractable memory related to drug addiction OBJECTIVES AND METHODS: To investigate the role of associative learning in methamphetamine addiction and the underlying neurobiological mechanism, methamphetamine self-administration, oral sucrose self-administration, chemogenetic neuromanipulation, and fiber photometry in mice were performed in this study. We reported that associative learning increased methamphetamine-induced self-administration, but not oral sucrose self-administration. In addition, the enhancement of methamphetamine-induced self-administration was independent of more methamphetamine consumption, and remained with higher drug-taking and motivation in the absence of visual cues, suggesting the direct effects of the associative learning that enhanced methamphetamine-induced self-administration. Moreover, chemogenetic inactivation of the secondary visual cortex (V2) reduced the enhancement of the drug-taking induced by associative learning but did not alter sucrose-taking. Further fiber photometry of V2 neurons demonstrated that methamphetamine-associative learning elicits V2 neuron excitation, and sucrose-associative learning elicits V2 neuron inhibition. Therefore, this study reveals the neurobiological mechanism of V2 excitability underlying how associative learning participates in the formation of intractable memory related to drug addiction, and gives evidence to support V2 as a promising target for stimulation therapy for methamphetamine addiction.

Flutter characteristics of a sheet with an elastic support in three-dimensional uniform flow

In the manufacturing processes of thin flexible plates (sheets) such as polarizing films, the flutter can be caused to the sheets due to the interaction between the motion of the sheets and fluid flow. Then, the flutter can cause serious damage to the sheets, leading to the wrinkles and scratches. Thus, it is crucial to investigate a detailed characteristics and excitation mechanism of the flutter. In the present study, a detailed flutter characteristics and excitation mechanism of a rectangular sheet with an elastic support is investigated. The elastic support is implemented using a fine flexible wire. The influence of bending stiffness of the support section on the flutter velocity and frequency is clarified through wind-tunnel experiments and numerical analysis. Moreover, the work done by the fluid force on the sheet surface was determined.The flutter velocity and frequency drastically decrease owing to decrease in bending stiffness of the support section regardless of the aspect and mass ratio. Then, the positive work region around the leading edge of the sheet expands owing to the large-amplitude oscillation around the leading edge. The expansion of positive work region owing to a large-amplitude oscillation around the leading edge of the sheet destabilizes the system.

Optical Nonreciprocity in a Multimode Cavity Optomechanical System Controlled by Dynamic Casimir Force

AbstractThe phenomenon of nonreciprocity arises from the disruption of time reversal symmetry, enabling the one‐way transfer of signals through specific channels. In the framework of cavity optomechanics, this symmetry breaking is attributed to a nonuniform radiation pressure force resulting from the interaction between light and matter. This study investigates a hybrid cavity optomechanical system (COMS) comprising two optical modes, directly coupled to each other via photon hopping interaction and indirectly via a common mechanical excitation in the form of a movable mirror, and an additional parallel metallic plate that induces a dynamical Casimir force (DCF) interaction between the plates. The two optical cavities are driven by two strong laser fields, accompanied by two weak probe classical fields from each port. The primary focus lies in exploring the nonreciprocal behavior of the light field across ports one and two, strongly manipulated by the DCF. The DCF plays a pivotal role in providing extra degrees of flexibility and manipulation in controlling the nonreciprocal signal transmission by modifying the resonance conditions of the fields within the hybrid COMS and is responsible for the amplification and swapping of information between the two ports.

Study on the effect and mechanism of microwave excitation on the activity of recycled powder of waste concrete

By crushing the prepared cement paste, the recycled powder (RP) was prepared by grinding. The study systematically investigated the effects of microwave power and activation time on the activity of RP. The results showed that the maximum enhancement in the activity of RP occurs when the microwave power is set to 490 W and the activation time is 10 minutes, with the activity increased by 14 %, 15 %, and 22 % at 3, 7, and 28 days, respectively. After microwave activation of RP, the decomposition of C-(A)-S-H and ettringite in the RP provides calcium, silicon, and aluminum phases, and the evaporation of bound water promotes the secondary hydration of RP. After microwave activation, the content of calcium oxide (CaO) in the RP increases, while the contents of silicon dioxide (SiO2) and alumina oxide (Al2O3) decrease; Adding activated RP to prepare mortar generates more hydration products to fill the pores, making the structure more compact. Compared with the control group, the porosity of the MRP-5 group decreased by 2.38 %.

Nonlinear dynamic analysis of aircraft CFRP sandwich wings under explosive blast loading: Introducing SVM-DNN algorithm to predict dynamical information

The aircraft wings are a crucial component, particularly during mechanical shock excitation. Thus, for the first time, an inventive adaptable model to simulate the nonlinear dynamics of the wings under explosive blast loading at the moment of the collision is described in this article. It is crucial to increase the structure's stability because of explosive blast loading. The mentioned structure is made of two composite face sheets and a carbon fiber-reinforced polymer (CFRP). Functionally graded (FG) graphene origami (GOri)-enabled auxetic metallic metamaterial (GOEAM) is introduced to improve the stability of this kind of applicable structure, especially in air maneuvers. The analysis is conducted utilizing Reddy's third-order shear deformation of Reddy theory (TSDRT), incorporating Hamilton's principle and Von Kármán nonlinear geometric assumptions. The governing and boundary equations are accurately computed at the domain and boundary edges of the doubly curved structure. The coupled mesh-free radial point interpolation method (MRPIM) and Newton-Raphson method are applied for numerically simulating the current doubly curved structure by employing Newmark's temporal integration method with a constant-average acceleration approach. The present findings are cross-checked against the machine learning method and open-source results from the literature. Based on physical data, machine learning integrates supervised machine learning to predict the nonlinear vibration of the system. In this case, nonlinear transient bending properties are found using hybrid machine learning methods and solutions. The findings demonstrate the significance of GOEAM for nonlinear vibrations of the composite system. The current study's conclusions could be used as a benchmark and useful recommendations for future structural design techniques with enhanced features.

Unraveling the Role of Enkephalin Signaling in Respiratory Control

Opioid-induced respiratory depression (OIRD) is the primary cause of death during opioid overdose characterized by a dramatic decrease in respiratory frequency and regularity. Opioid drugs cause neural depression in the ventral respiratory column (VRC) of the medulla via activation of mu-opioid receptors (MORs) that partially contribute to breathing cessation. Nonetheless, little is known about the role of endogenous opioid signaling in respiratory modulation. This study investigates the role of endogenous MORs ligands, enkephalins encoded by the Penk gene, in breathing control. To test whether enkephalin-expressing neurons of the preBӧtzinger Complex (preBӧtC) — the inspiratory rhythm-generating region of the VRC — are necessary for breathing rhythmogenesis, we permanently silenced the region’s Penk+ population via AAV1 injections encoding tetanus toxin light chain. Using whole-body plethysmography, we recorded the animals' respiratory performance within 14 days post-injection. During the second week of testing, we observed unexpected mortality in some experimental but not control animals; post-hoc analysis of breathing traces revealed the development of severe tachypnea in succumbed mice. These data suggest that Penk+ preBӧtC cells are integral for normal respiration. Still, these observations did not assess the specific contribution of enkephalin, as opposed to other types of signaling, to breathing stability. To directly dissect the effects of enkephalin on respiratory rhythm, we utilized optogenetics and pharmacological approaches in brainstem slice preparation from neonatal mice. Brief optogenetic activation of Penk+ neurons in the preBӧtC evoked population bursts while prolonged stimulation increased the rhythm frequency. However, the application of MOR antagonist Naloxone did not affect the network’s responses to light stimulations indicating the lack of MOR/enkephalin involvement in mediating these excitatory effects. High fidelity and temporal coordination of evoked bursts implicated glutamatergic transmission as the primary mechanism of excitation. Likewise, we were able to optogenetically drive respiratory rhythm in urethane-anesthetized spontaneously breathing adult mice by stimulating the preBӧtC. Further, there was a small but significant difference in breathing responses in the presence of Naloxone compared to control conditions. We hypothesized that longitudinal projections to the VRC that might be disrupted during slice preparation contributed enkephalin to the respiratory circuits in the whole-body preparation. We utilized recombinase-dependent reporter mice crosses and retrograde AAV tracers to identify brain-wide Penk inputs to the preBӧtC. Using conventional and light sheet fluorescence microscopy, we located regions in the pons, midbrain, and forebrain that send direct enkephalinergic projections to the VRC. Functional characterizations of these projections will potentially uncover state-dependent mechanisms of respiratory modulation via endogenous opioids. Untimely, this study will help elucidate the role of enkephalin signaling in breathing control and may establish therapeutic targets for preventing OIRD. R01HL166317, R00HL145004. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Granular vibration pumping system for handling and characterizing particulate materials.

A unique setup for a granular vibration pumping system was developed to ease the installation into a wide variety of granular handling processes and provide flexible options for granular physics research. Although the granular vibration pumping system can notably lift granular materials with an oscillating pipe, the climbing mechanism and related granular physics are yet to be clarified thoroughly. The new setup employs an eccentric cam mechanism as the excitation source, a linear system with dust tolerance, and a recording system, making it simple, compact, and adaptable for extending experiments. The excitation mechanism generated a clear sinusoidal vibration in the pipe, realizing better reproducibility of the climbing motions of glass beads. Moreover, the compact design facilitates the close placement of multiple pipes vibrating individually, which affects the transport performance. In addition, various types of sample cells that store particles and the imaging system allow for the detailed observation of particle motions in the pipes and even the sample cells. This developed system provides easy and accurate tuning of the existing parameters of the granular vibration pumping system, as well as new options for a further understanding of granular physics.

Ultrasound Viscoelastography by Acoustic Radiation Force: A State-of-the-Art Review.

Ultrasound elastography (USE) is a promising tool for tissue characterization as several diseases result in alterations of tissue structure and composition, which manifest as changes in tissue mechanical properties. By imaging the tissue response to an applied mechanical excitation, USE mimics the manual palpation performed by clinicians to sense the tissue elasticity for diagnostic purposes. Next to elasticity, viscosity has recently been investigated as an additional, relevant, diagnostic biomarker. Moreover, since biological tissues are inherently viscoelastic, accounting for viscosity in the tissue characterization process enhances the accuracy of the elasticity estimation. Recently, methods exploiting different acquisition and processing techniques have been proposed to perform ultrasound viscoelastography. After introducing the physics describing viscoelasticity, a comprehensive overview of the currently available USE acquisition techniques is provided, followed by a structured review of the existing viscoelasticity estimators classified according to the employed processing technique. These estimators are further reviewed from a clinical usage perspective, and current outstanding challenges are discussed.

Discrete Anisotropy Model of Heterogeneous Cardiac Tissue Predicting the Occurrence of Symmetry Breaking of Reentrant Activity

Cardiac arrhythmias are a major cause of cardiovascular mortality worldwide. Functional heterogeneity of cardiac tissue is an inevitable arrhythmogenic condition that may create nonlinear wave turbulence or reentry with subsequent arrhythmia initiation. The relation between propagation heterogeneity and the onset of reentry is of great theoretical and practical importance. Here, we present a conceptual representation of heterogeneous tissue expressed through alternating local and global tissue anisotropy with discreteness of membrane conductance. To contrast the influence of distributed heterogeneity, we investigated the interaction of a high-frequency wavetrain at a sharp anisotropy-symmetric obstacle. The revealed tendency of a heterogeneous system to form reentry was formalized into the single concept of a vulnerable frequency corridor that can be estimated experimentally. Using the joint in vitro–in silico approach, we defined an anomalous stable growth of a unidirectional block in the vicinity of an obstacle, depending on the direction of the anisotropy vector. This effect explains the limited applicability of homogeneous models to predicting the occurrence of primary reentry. Furthermore, computer simulations showed the special role played by other possible mechanisms of excitation, as ephaptic intercellular coupling, in the formation of a unidirectional block of conduction and reentry onset, which could not be predicted by conduction velocity measurements.

Flow excitation mechanisms of unbalanced impeller forces after pump power-trip of ultra-high head pump-turbines

Flow excitation mechanisms of unbalanced impeller forces after pump power-trip of ultra-high head pump-turbines

Indirect evidence of Bi3+ valence change and dual role of Bi3+ in trapping electrons and holes for multimode X-ray imaging, anti-counterfeiting, and non-real-time force sensing

Discovering bismuth based smart materials that can respond to thermal, mechanical, and wide range X-ray to infrared photon excitation remains a challenge. Such materials have various uses like in advanced information encryption. In this work, valence state change between Bi2+, Bi3+, and Bi4+, and the dual role of Bi3+ in trapping electrons and holes have been studied in Bi3+ or/and Ln3+ (Ln=Tb or Pr) doped LiScGeO4 family of compounds by vacuum referred binding energy (VRBE) diagram construction, thermoluminescence, and spectroscopy. Electron release from Bi2+ has been evidenced. It can be used to experimentally determine the VRBE in the Bi2+ 2P1/2 ground state and to realize Bi3+ negative quenching luminescence. Particularly, a new force induced charge carrier storage phenomenon has been discovered for non-real-time force recording. Wide range of emission tailorable afterglow, unique Bi3+ ultraviolet-A, white, and infrared afterglow have been demonstrated by using Bi3+ as a hole trapping and recombination center and using energy transfer processes from Bi3+ to Tb3+, Pr3+, Dy3+, or Cr3+. Proof-of-concept advanced anti-counterfeiting, information encryption, and X-ray imaging will be demonstrated. This work not only develops smart storage phosphors, but more importantly unravels the valence change between Bi2+, Bi3+, or Bi4+ and how it can affect the trapping and release of charge carriers with thermal, optical, or mechanical excitation. This work therefore can promote the discovery and development of Bi3+ based smart materials for various applications.

Effect of Glycerol Mechanical Excitation on the Phase Evolution and Hydration Activity of Steel Slag

Effect of Glycerol Mechanical Excitation on the Phase Evolution and Hydration Activity of Steel Slag

Preparation and alkali excitation mechanism of coal gangue-iron ore tailings non-sintering ceramsite

Non-sintering ceramsite is known for its simplicity in preparation technology and low production costs. The efficient utilization of industrial solid waste for non-sintering ceramsite production has garnered significant attention in green building materials within the framework of low carbon and environmental protection principles. This study focuses on preparing non-sintering ceramsites using non-active solid waste materials, specifically coal gangue and iron ore tailings. Firstly, a single-factor test was conducted to determine the optimal dosage of coal gangue and iron ore tailings. Subsequently, orthogonal tests were performed to investigate the influence of fly ash, NaOH, and aluminum powder on the mechanical properties of non-sintering ceramsite. Finally, the alkali excitation mechanism was elucidated through X-ray diffraction and SEM electron microscope scanning. The results reveal that the optimal proportions for coal gangue and iron ore tailings are 10 % and 35 %, respectively. Among the factors examined, NaOH dosage exerts the most significant impact on the compression strength and bulk density of non-sintering ceramsite, while aluminum powder dosage has the greatest effect on the 1-hour water absorption of the material. The optimal mixing ratio was determined with a total solid waste dosage of 73 %, meeting the national 600-grade standard for non-sintering ceramsite across all performance criteria. Furthermore, the alkali excitation process effectively activates the reactivity of fly ash and coal gangue. This activation leads to the generation of calcium alumina and C-S-H gel, along with other hydration products, which intertwine to form a dense gel structure. This structural enhancement further contributes to the improved performance of non-sintering ceramsite.

Mechanical characteristics analysis of high dimensional vibration isolation systems based on high-static-low-dynamic stiffness technology

Large floating raft vibration isolation systems (FRVISs) based on high-static-low-dynamic stiffness (HSLDS) technology offer excellent low frequency vibration isolation performance with broad application prospects. However, the design process for these complex high-dimensional coupled nonlinear systems remains poorly developed, particularly when applied for ocean-going vessels that experience rolling and pitching motions. The present work addresses this issue by establishing a six-degree-of-freedom HSLDS vibration isolation model for FRVISs composed of eight isolators, and the model is applied to fully analyze the swing stability and multidimensional vibration isolation performance of these systems. The influence of nonlinearity on the mechanical properties of the vibration isolators is analyzed more clearly by assuming that each vibration isolator realizes nonlinear HSLDS characteristics in the z direction and linear characteristics in the x and y directions. The results demonstrate that the swing displacement responses of the system are greatly reduced under weak nonlinearity, which reflects the high static stiffness and high static stability characteristics of an HSLDS system. The multidimensional vibration isolation performance of the system is evaluated according to the impacts of nonlinearity, the installation height Hz of the isolators, and the relative position Dr of the two middle isolators. The results of analysis demonstrate that applying a value of Hz = 0 produces the best vibration isolation performance overall under strong nonlinearity by avoiding unnecessary secondary peaks in the force transmission rate under harmonic mechanical excitation and ensuring a maximum high-frequency vibration isolation effect. However, applying a weak nonlinearity is better than a strong nonlinearity if Hz is not zero. In contrast, Dr has little effect on the vibration isolation effect of the raft in the x, y, and z directions. Therefore, an equidistant installation with Dr = 0.5 would be considered ideal from the standpoint of installation stability.

The influence of gear load distribution based on coupled systems on gearbox meshing noise

Introduction: With the rapid development of the gearbox manufacturing industry, the internal gear response has received attention, and the control of meshing noise during gear operation has been studied. Conventional noise reduction methods are usually based on gear order, and with the improvement of gearbox manufacturing technology, this method gradually becomes difficult to cope with a wide range of data.Methods: To expand the search domain of noise control systems, this study combines gear response and gear order, and adds the condition of gear uniform load. For common noise reduction problems in composite systems, this study improves the time-varying stiffness excitation mechanism and generates a coupled system.Results: Finally, this study conducts experiments on the Gmnoi dataset and compares it with three systems including quantum genetics to verify the superiority of the proposed system. The suppression effects of the four systems on gear meshing noise were 98.4%, 95.8%, 93.5%, and 92.7%, respectively. Their highest performance for different gear groups was 623, 514, 406, and 423, respectively.Discussion: The experimental results showed that the proposed coupling system has strong robustness and high accuracy in controlling gearbox meshing noise, and is of great significance in reducing noise pollution and improving the working environment of the gearbox.

A three-dimensional coupled structure triboelectric nanogenerator for vertical and horizontal mechanical energy harvesting and fitness gait monitoring

Recently, the self-powered monitoring device used for wearable sensors has attracted attention from various industries. It is worth noting that previous self-powered sensors were mostly focused on unidirectional sensing and monitoring, and few sensors can achieve both longitudinal and transverse sensing functions simultaneously. Here, we designed an arched and stacked coupling structure triboelectric nanogenerator (AS-TENG) to harvest horizontal and vertical mechanical energy. Meanwhile, the AS-TENG can simultaneously achieve sensing effects on longitudinal pressure and transverse pulling force. According to the results, the pulling force sensing sensitivity of AS-TENG can reach 2.415 V N−1, and the pressure sensing sensitivity of AS-TENG can arrive at 2.78 V N−1. Furthermore, under longitudinal 6 Hz mechanical motion excitation, the open-circuit voltage (Voc) and short circuit current (Isc) of AS-TENG can reach 28.21 μA and 173.25 V, respectively. The transfer charge (Qsc) of AS-TENG can arrive at 169.7 nC. The AS-TENG can achieve a maximum output power of 2.02 mW at a 3 MΩ load. Moreover, the sensing signal pulse width of AS-TENG can reach 180 ms, which is higher than the traditional arch structure’s 110 ms, indicating the unique advantages of AS-TENG in future fitness monitoring. This study provides a 3D triboelectric multi-directional sensor that will serve the fields of intelligent wearable fitness and sports.

Assessing patient transport conditions during ambulance transit.

Emergency ambulances play a vital role in medical rescue and patient transportation, but their transit can impact patient health due to vehicle dynamic forces and vibrations. This study evaluates patient transport conditions on a stretcher subjected to vertical vibration excitation from road unevenness. Using an eight-degree-of-freedom numerical model, we analyze the construction parameters of a medical stretcher's support and vehicle suspension. Actual experimental data from an emergency vehicle were utilized to assess the vibration conditions experienced by both the stretcher and the ambulance floor. The model is adjusted based on measurements, specifically targeting the main vibration modes. The investigation involves determining temporal responses for vertical accelerations and characterizing vibration modal parameters under various transportation conditions. Notably, several system natural frequencies fall within the range of human body frequencies, making them susceptible to mechanical excitation, particularly in the human neck, abdomen, and spine. A sensitivity analysis underscores the influence of medical stretcher support structure parameters on patient comfort. Increasing support stiffness, which alters the stretcher's natural frequency, and damping coefficient reduce vibration propagation between the vehicle and the patient. Additionally, the research predicts the model's dynamic behavior on roads with low-quality pavement, indicating vibrational amplitudes that could potentially be discomforting and unhealthy for individuals. The study illustrates a vibration exposure period on a class E road, revealing that transportation longer than 25 min may cause damage to patient health.

The in-situ excitation on internal electrode of DBD-OES system for cadmium sensitive detection

The utilization of microplasma excitation sources in miniature systems offers reliable tools for the portable detection of heavy metal contamination. Dielectric barrier discharge (DBD)-based optical emission spectrometry has emerged as a significant technique for the detection of metal ions recently. Here, a sensitive miniature DBD-OES system for cadmium enrichment and detection is developed. A piece of ceramic tube with abundant hydroxyl (-OH) and alumina (AlO) functional groups is used for cadmium pre-concentration and serve as a part of the internal electrode of the DBD. When microplasma generates, the cadmium on the surface of the internal electrodes is desorbed and in-situ excited, and the characteristic emission line of cadmium appears. The mechanism of cadmium excitation on ceramic tube, the characteristics of the microplasma excitation and the enrichment on the internal electrode are discussed. Under the working conditions, the emission intensity of cadmium shows linear relationship within the range of 0.5–8 μg L−1, and the limit of detection (LOD) is 0.3 μg L−1. Finally, a series of water samples are determined to validate the applicability of the present system.

Operational mechanism of valved-pulsejet engines

The study investigates twelve configurations of the self-aspirated valved pulsejet, focusing on its operational mechanism. It begins by characterizing the engine's acoustic field with varied boundary conditions, revealing an extended effective acoustic length beyond the combustion chamber and tailpipe sections when the valve is open. Radial and lateral velocity fluctuations are hypothesized as causes for vortex structure generation. Analysis of reacting pulsejets using gasoline and ethanol fuels shows that the operating frequencies are unaffected by fuel type, with geometric arrangement as the primary frequency factor. Fluctuations in dynamic pressure, microphone readings, and thrust characterize engine stability, impacted by low-frequency modes and higher harmonics. Tailpipe length emerges as the key geometric factor for performance enhancement with the medium size being the optimal option. Pressure field analysis demonstrates shock wave generation during ignition, serving as an excitation mechanism. Notably, different configurations with varied operating frequencies can yield equivalent thrust, indicating that thrust production is not solely dependent on pressure rise during combustion, despite similar pressure rise observed across most cases.

Piezo-Fenton catalysis in Fe3O4-BaTiO3 nanocomposites: A low-cost and highly efficient degradation method without the additive of H2O2 or Fe(II) ions

The Fenton reaction, an effective advanced oxidation process (AOP) for degrading organic pollutants, requires the addition of H2O2 that is expensive and not environmentally friendly to some extent. It has been reported that piezocatalysis can generate H2O2 under mechanical excitation. Therefore, it is promising to carry out the Fenton catalysis utilizing in situ H2O2 generated by piezocatalysis. However, the current piezocatalysis-assisted Fenton (Piezo-Fenton) reaction was realized by adding piezoelectric nanoparticles and Fe(II) ions to pollutant solutions, which would induce more iron-based chemicals that are not easy to recycle. Herein, Fe3O4-BaTiO3 nanocomposites were prepared to demonstrate the feasibility of piezo-Fenton catalysis without the addition of H2O2 or Fe(II) ions. The organic dye degradation efficiency of 98.2% is obtained using Fe3O4-BaTiO3 nanocomposites in the acidic solution, one-third and two-thrid greater than that of pure piezocatalysis and that of iron-based Fenton reaction, respectively. Moreover, since the piezocatalysis process is the rate-determining step of the whole piezo-Fenton reaction, all the H2O2 generated can be consumed. Considering that the solid nanocomposites can be magnetically recycled, piezo-Fenton catalysis leaves no additional chemicals in clean water and thus provides an environmentally friendly and low-cost approach for organic dye degradation.