Experimental System Research Articles

Chiral active systems near a substrate: Emergent damping length controlled by fluid friction

Chiral active fluids show the emergence of a turbulent behaviour characterised by multiple dynamic vortices whose maximum size varies for each experimental system, depending on conditions not yet identified. We propose and develop an approach to model the effect of friction close to a surface in a particle based hydrodynamic simulation method in two dimensions, in which the friction coefficient can be related to the system parameters and to the emergence of a damping length. This length is system dependent, limits the size of the emergent vortices, and influences other relevant system properties such as the actuated velocity, rotational diffusion, or the cutoff of the energy spectra. Comparison of simulation and experimental results of a large ensemble of rotating colloids sedimented on a surface shows a good agreement, which demonstrates the predictive capabilities of the approach, which can be applied to a wider class of quasi-two-dimensional systems with friction.

Analysis and control design for input‐series output‐parallel multi‐channel inductive power transfer system

AbstractTo realize high‐power inductive power transfer (IPT) for fast charging of electric vehicles (EVs), an input‐series output‐parallel (ISOP) multi‐channel IPT system is analysed in this paper, and an output control strategy based on single neuron controller is proposed to improve the stability of the system. Firstly, the steady‐state operating conditions of ISOP‐IPT system is analysed based on different compensation networks which shows that the constant‐voltage‐output compensation networks are more suitable for the proposed circuit structure. Then, to improve the voltage equalization between channels, an open‐loop control method combining parameter design and phase‐shift control is proposed against different coil misalignments. At the same time, based on the single neuron controller, the system output closed‐loop control is realized without the need of accurate system modelling. Finally, a three‐channel ISOP‐IPT experimental system was constructed, which operated stably at 2.9 kW with a power efficiency of 93.38%. The system closed‐loop control with control time of 22 ms is realized. The voltage equalization control offset is less than 1%.

Poplar Adventitious Roots Induced by Stem Canker Pathogens: An Experimental System for Studying Roots Biology and Light Response-Related Processes

Poplar Adventitious Roots Induced by Stem Canker Pathogens: An Experimental System for Studying Roots Biology and Light Response-Related Processes

A novel plasmid‐based experimental system in Saccharomyces cerevisiae that enables the introduction of 10 different plasmids into cells

A novel plasmid‐based experimental system in <i>Saccharomyces cerevisiae</i> that enables the introduction of 10 different plasmids into cells

A Consistent Comparison of Upper Subcritical Limit Methods

This study conducts a consistent and comprehensive comparison of several methods for estimating upper subcritical limits (USLs) for nuclear criticality safety analysis. To eliminate inconsistency caused by the discrepancy between the estimated covariance data and the true degree of uncertainty present in nuclear data, the experimental system eigenvalues k exp were assumed to equal the calculated eigenvalue for the systems using nominal ENDF/B-VII.1 cross sections, and the estimated calculated eigenvalue k calc was assumed to equal the calculated eigenvalue for the systems using nuclear data from one perturbed cross-section library. USLs are estimated for a variety of validation application cases using the Whisper, TSURFER, and USLSTATS tools and are compared to a reference 95/95 limit. The TSURFER approach produced the strongest agreement with the reference USLs; the Whisper produced USLs that were reliably conservative compared to the reference USL; and the USLSTATS approach experienced difficulty consistently producing accurate USL estimates. Last, this study observed a noteworthy discrepancy when using Cholesky decomposition to randomly sample neutron cross-section covariance data that are small in magnitude.

Fan noise radial mode detection based on [formula omitted] regularization method

Radial mode detection has been widely employed in fan noise research. Many radial mode detection algorithms by conducting the convex L1 norm optimization have been proposed by taking advantage of the fact that the fan noise sound field is usually dominated by a limited set of radial modes. Nevertheless, L1 norm optimization has been shown to be suboptimal and cannot enforce further sparsity. A fan noise radial mode detection method based on L1/2 regularization algorithm is proposed in this paper to improve its robustness and dynamic range. This method employs the L1/2 regularization to directly solve the in-duct sound propagation model. Synthesized simulations indicates that the L1/2 regularization method can detect the correct radial mode order and amplitude under low signal-to-noise ratio. Moreover, the new method is insensitive to regularization parameter. An experimental system of radial rake is implemented to validate the new method. It is shown that the L-curve method, which do not require any prior information of the acoustic mode distribution or contaminating measurement noise, is an appropriate choice of the regularization parameter determination method for the L1/2 regularizer. It is demonstrated that the new L1/2 regularization method can enhance the mode sparsity, especially under low signal-to-noise ratio. Moreover, the resolution and dynamic range can be improved by the L1/2 regularization method, which makes it an effective and robust fan noise radial mode detection technique in practical applications.

Robust finite-temperature many-body scarring on a quantum computer

Mechanisms for suppressing thermalization in disorder-free many-body systems, such as Hilbert space fragmentation and quantum many-body scars, have recently attracted much interest in foundations of quantum statistical physics and potential quantum information processing applications. However, their sensitivity to realistic effects such as finite temperature remains largely unexplored. Here, we have utilized IBM's Kolkata quantum processor to demonstrate an unexpected robustness of quantum many-body scars at finite temperatures when the system is prepared in a thermal Gibbs ensemble. We identify such robustness in the PXP model, which describes quantum many-body scars in experimental systems of Rydberg atom arrays and ultracold atoms in tilted Bose-Hubbard optical lattices. By contrast, other theoretical models which host exact quantum many-body scars are found to lack such robustness and their scarring properties quickly decay with temperature. Our study sheds light on the important differences between scarred models in terms of their algebraic structures, which impacts their resilience to finite temperature. Published by the American Physical Society 2024

Utilization of a Human Liver Tissue Chip for Drug-Metabolizing Enzyme Induction Studies of Perpetrator and Victim Drugs.

Polypharmacy-related drug-drug interactions (DDIs) are a significant and growing healthcare concern. An increasing number of therapeutic drugs on the market underscores the necessity to accurately assess new drug combinations during pre-clinical evaluation for DDIs. In vitro primary human hepatocytes (PHH) models are only applicable for short term induction studies due to their rapid loss of metabolic function. Though co-culturing non-human stromal cells with PHH has been shown to stabilize metabolic activity long-term, there are concerns about human specificity for accurate clinical assessment. In this study, we demonstrate a PHH-only liver microphysiological system (MPS) in the Liver Tissue Chip (LTC) is capable of maintaining long-term functional and metabolic activity of PHH from three individual donors, and thus a suitable platform for long-term DDI induction studies. The responses to rifampicin induction of three PHH donors were assessed using CYP activity and mRNA changes. Additionally, victim PK studies were conducted with midazolam (high clearance) and alprazolam (low clearance) following perpetrator drug treatment, rifampicin-mediated induction, which resulted in a 2-fold and a 2.6-fold increase in midazolam and alprazolam intrinsic clearance values respectively compared to the untreated liver MPS. We also investigated the induction effects of different dosing regimens of the perpetrator drug (rifampicin) on CYP activity levels, showing minimal variation in the intrinsic clearance of the victim drug (midazolam). This study illustrates the utility of the LTC for in vitro liver-specific DDI induction studies, providing a translational experimental system to predict clinical clearance values of both perpetrator and victim drugs. Significance Statement This study demonstrates the utility of the Liver Tissue Chip (LTC) with primary human hepatocyte (PHH)-only liver microphysiological system (MPS) for drug-drug interaction (DDI) induction studies. This unique in vitro system with continuous recirculation maintains long-term functionality and metabolic activity for up to 4 weeks, enabling the study of perpetrator and victim drug pharmacokinetics, quantification of drug-induced CYP mRNA and activity levels, investigation of patient variability, and ultimately clinical predictions.

Study on Multi-Parameter Variation of Smoke Flow in Inclined Roadway Fire

ABSTRACT Based on the fluid similarity theory, a “Mine inclined roadway fire simulation experimental system” with similarity ratio of 1:20 is established. The temperature, velocity, density and dynamic pressure of fire smoke under different inlet wind speed (0.5 m/s, 1.0 m/s, 1.5 m/s) were tested and analyzed, and the distribution of temperature, velocity, density and dynamic pressure of inclined roadway during fire was simulated and analyzed by Ansys numerical simulation software. The research shows that: The higher the inlet wind speed, the faster the heat diffusion and the temperature field tends to be flat and long, the wind speed changes in advance and the change is drastic, the gas density decreases, the dynamic pressure first decreases and then increases and then tends to stabilize, but the change trend of temperature, wind speed, gas density and pressure in the overall combustion process remains unchanged. The numerical analysis results are in good agreement with the experimental results. By studying the change law of smoke temperature, velocity, density and dynamic pressure of coal mine inclined roadway fire, the theory of coal mine roadway fire is further perfected, and the level of coal mine fire prevention and rescue is improved.

Experimental encircling of an exceptional point in a two degrees of freedom system: overview and application to noise control

When a resonator is added to an acoustic cavity or a vibrating structure, a new resonance frequency, or pole, is created in the system. When dissipation is present, this may breakdown when some parameters are finely tuned. This phenomenon, typical of non-Hermitian dynamics is called an exceptional point in the parametric space where two (or more) eigenvalues, as well as their associated eigenvectors, coalesce. In the recent years, EPs have gained interest in physics because of the counter-intuitive concepts associated with them. In the fields of acoustics and vibration, understanding EP may lead to a better comprehension of modal energy exchanges and decay. This work aims at exploring the key concepts related to EPs by revisiting the well-known coupled pendulums problem in the presence of damping. First, the free response of the experimental system is investigated after tuning it on an EP. Then an encircling is performed by varying the parameters through time. Our experimental results illustrate in a pedagogical manner nearly-optimal dissipation, energy exchange and chirality effects which have been recently evidenced in physics.

Charging of an Air–Rock Bed Thermal Energy Storage under Natural and Forced Convection

An air-rock bed thermal storage system was designed for small-scale powered generation and analyzed with computational fluid dynamics (CFD) using ANSYS-Fluent simulation. An experimental system was constructed to compare and validate the simulation model results. The storage unit is a cylindrical steel container with granite rock pebbles as a storage medium. The CFD simulation used a porous flow model. Transient-state simulations were performed on a 2D axisymmetric model using a pressure-based solver. During charging, heat input that keeps the bottom temperature at 550 °C was applied to raise the storage temperature. Performance analysis was conducted under various porosities, considering natural and forced convection. The natural convection analysis showed insignificant convection contribution after 10 h of charging, as observed in both average air velocity and the temperature profile plots. The temperature distribution profiles at various positions for both convection modes showed good agreement between the simulation and experimental results. Additionally, both cases exhibited similar temperature growth trends, further validating the models. Forced convection reduced the charging time from 60 h to 5 h to store 70 MJ of energy at a porosity of 0.4, compared to natural convection, which stored only 50 MJ in the same time. This extended charging period was attributed to poor natural convective heat transfer, indicating that relying solely on natural convection for thermal energy storage under the given conditions is not practical. Using a small fan to enhance heat transfer, forced convection is a more practical method for charging the system, making it suitable for power generation applications.

TRLR-02 TARGETING GLIOBLASTOMA MICROENVIRONMENT TO UNLEASH IMMUNE FORCES

Abstract Brain cancer has persistently eluded therapeutic advances over the past three decades. Here, we aim to raise awareness of the potential differences between the cancer microenvironment within the brain vs. peripheral organ cancers, which may contribute to the therapeutic setbacks observed in brain cancer treatment. While the blood-brain barrier has long been implicated in drug impermeability, its impact on brain cancer may extend far beyond mere drug exclusion. Studies have shown that soluble factors such as VEGF are more concentrated in brain cancer than in any other malignancies. Moreover, recent studies revealed that VEGF, TWEAK, and others can also press on the immune brakes. Therefore, we hypothesize that normalizing the tumor microenvironment could pave the way for effective therapeutic interventions, especially immunotherapy. Our in vitro studies confirmed abundant production of VEGF by glioblastoma 1 (GBM1) cell line, which is exceptionally well scavenged by the anti-VEGF antibody – bevacizumab. Moreover, in vitro, co-culture of T cells and GBM1 cell line without vascular component demonstrated no therapeutic activity of bevacizumab or typical immunotherapeutic drug – anti-PD1 checkpoint inhibitor – nivolumab given in monotherapies. However, a combination of both antibodies revealed therapeutic efficacy in a dose-dependent manner in our experimental system. Currently, intravenous delivery of bevacizumab is the standard of care in patients with glioblastoma recurrence, but its effectiveness has not been proven in this group of patients. Intravenous nivolumab failed in clinical trials. Based on our observations and the negligible penetration of antibodies to the brain, we hypothesize that transiently opening the blood-brain barrier may be necessary to enhance antibody delivery to the tumor microenvironment, alleviate immune suppression, and unlock immune cell activity. Therefore, achieving high antibody concentrations in brain cancer tissue, coupled with a combination of classic checkpoint inhibitors with scavengers of soluble immunosuppressive molecules, could herald a new era of brain cancer therapy.

Selective Rashba Spin-Orbit Coupling Manipulation in Triple Quantum Wells

Abstract We explore the Rashba (α) spin-orbit coupling (SOC) manipulation in triple quantum wells (QWs) with three subbands occupied in the presence of the external gate voltage Vb. Diverse behaviors of can be demonstrated by adjusting the structural parameters of the wells. Specifically, the first (lowest) subband always has larger Rashba coupling against the variations in the structural parameters and Vb than the other subbands, conducive to spin detection. α of the second and third subbands take on dual (magnitude and sign) change owing to the regulation of the inner barrier height δ, may facilitating the realization of stretchable persistent spin helix in multiple QWs. Strikingly, α of the third subband can keep essentially zero in a wide gate range corresponding to asymmetrical QW structural configurations, by adjusting δ. However, when widening the well to a certain extent the diverse behaviors of α disappear. All these findings may shed light on selective and precise SOC control in QW systems for experiments.

Heat and mass transfer performance of multi-solute electroplating wastewater in spray evaporation separation process

Electroplating wastewater is complex in composition and contains many harmful substances. Based on the single droplet heat and mass transfer method, a one-dimensional mathematical model for the evaporation separation heat and mass transfer process of multi-solute electroplating wastewater is established. In order to validate the model, the experimental system of evaporation separation tower is established, and Nusselt numbers corresponding to metal ion solutions are fitted, reliabilities of models are also verified. The maximum relative errors of mathematical models are within 10.0 %. In addition, effects of the type and concentration of metal ions and air inlet temperature on heat and mass transfer characteristics of spray separation tower are investigated. Experimental results show that when the wastewater inlet concentration is the same, the improvement effects of increasing air inlet temperature on evaporation and separation performance from high to low are ZnCl2, CuCl2, and NiCl2 solutions. When the air inlet temperature increases from 90 °C to 130 °C, the evaporation speed of ZnCl2, CuCl2 and NiCl2 solutions increase by 90.3 %, 84.3 % and 45.7 %, respectively. When the air inlet temperature is the same, with the increase of wastewater inlet concentration, the evaporation separation performance of electroplating wastewater in descending order is ZnCl2, CuCl2, and NiCl2 solutions.

Dynamics and experimental study of a novel proportional directional valve with displacement feedback groove controlled by high-speed switching valves

The intelligence of hydraulic roof support is an important guarantee for unmanned fully mechanized coal mining face. The water-based medium proportional directional valve is the main factor that restricts the intelligent realization of support system. The support control valve needs to meet the 2/3 (two-position three-way) structure, taking into account both manual and electro-hydraulic control functions. The current water-based proportional valve does not satisfy the structural or functional demands of the support system. In this paper, a novel 2/3 water-based proportional directional valve is presented based on the displacement-flow feedback principle, which has two control modes: manual on-off control and electro-hydraulic proportional control. The proportional valve comprises two main valve spools and two pilot valves. The pilot valve is composed of a 2/3 on-off valve with manual operation capability and a high-speed switching valve group controlled by PWM (Pulse Width Modulation). The mathematical model of the proportional valve is established, and the experimental system is built to verify the characteristics of proportional valve. The proportional valve can meet the special functional requirements of the support. In the proportional control mode, the adjustment of spool displacement is regulated through the modulation of PWM duty ratio, resulting in effective control performance of the proportional valve. Furthermore, the discontinuous flow of the high-speed switching valve causes the pressure fluctuation of the pilot hydraulic bridge. Increasing the carrier frequency of PWM can reduce the amplitude of control chamber pressure and spool displacement fluctuation. The findings of the study can offer valuable insights for the continued advancement and enhancement of water-based proportional valves used in hydraulic roof support systems.

Semi-analytical modeling and vibration characteristics analysis of the orthogonally stiffened cylindrical shell with variable cross-sections of stiffeners

The stiffened shell with variable cross-sections of stiffeners (SS-VC) has important applications in aerospace and other fields. Its excellent mechanical properties provide new possibilities for the design and performance improvement of stiffened structural parts. However, its dynamic modeling problems have been urgent to be solved. In this study, the dynamic model of the orthogonally stiffened cylindrical shell with variable cross-sections of stiffeners (OSCS-VC) is established by the semi-analytical method (SAM) and it can be described as follows. The displacement allowable functions of the structure are constructed by using the Gram-Schmidt orthogonalization method. Based on Sanders shell theory, the stress-strain relationships of the longitudinal and ring stiffeners with variable cross-sections are derived under the variable limit integration. The boundary spring stiffness is obtained by the inverse identification technique. The dynamic equation of OSCS-VC is established and solved by using the Lagrange equation. Then, a case study is carried out, the rationality of the semi-analytical dynamic model of OSCS-VC is verified by ANSYS engineering software, literature and the experiment system. Finally, based on the semi-analytical model of OSCS-VC, the influence of the characteristic parameters of cross-sectional functions (CSF) for the longitudinal and ring stiffeners on the natural frequencies is analyzed.

Real-time live imaging of cytosolic hydrogen peroxide and Ca2+ of Marchantia polymorpha gemmalings reveal immediate initial responses of plant cells triggered by nonthermal plasma irradiation.

Cold atmospheric pressure plasma generators capable of generating plasma under normal pressure and temperature conditions have recently been developed, and their biological applications have been extensively studied. Plasma irradiation has been reported to affect plant germination and growth; however, the molecular mechanism underlying these effects and initial cellular responses to plasma irradiation remains poorly understood. To unravel the molecular and cellular mechanisms underlying the effects of plasma irradiation on plants, we have been establishing novel experimental systems using a model liverwort Marchantia polymorpha. We here focused on the initial responses of plant cells to plasma irradiation. To investigate immediate cellular responses following plasma irradiation, we developed a new plasma device that allows irradiation under a microscope. Through integration with live fluorescence imaging, we established an experimental setup to track, the dynamics of intracellular concentration of H2O2 and Ca2+ as representative initial cellular responses. We revealed that plasma irradiation induced a rapid and transient increase in intracellular concentration of H2O2 and Ca2+ in Marchantia gemmalings. Pharmacological analyses suggested that the long-lived reactive species, H2O2, generated by the plasma generator was directly delivered into the plant cells. Competitive inhibitors of Ca2+ channels abolished the Ca2+ rise, suggesting that plasma irradiation immediately activate plasma membrane Ca2+ channel(s) to induce Ca2+ influx. Importantly, this study marks the inaugural demonstration of real-time monitoring of cytosolic H2O2 and Ca2+ dynamics in plants, triggered by plasma irradiation.

Photothermal measurement of material properties for translucent thermal barrier coatings

In this study, a photothermal nondestructive method was proposed to measure the material parameters of semi-transparent or translucent thermal barrier coatings (TBCs). We derived a theoretical model for the photothermal signal from a two-layer semi-infinite material system with a translucent first layer after a pulse laser excitation. Its solution was verified by numerical solution. A data regression algorithm based on a least-squares fitting was used for the determination of the material parameters in the translucent first layer material. To verify this new method, an experimental system was set up with a pulse laser for thermal excitation and an infrared camera for image acquisition of the thermal emission transient from several translucent EBPVD TBC samples. The predicted coating thickness is consistent with the measured value by an optical microscope. The predicted thermal conductivity and optical attenuation coefficients in the absorption and emission band are found to be in good agreement with reference values.

Simulation and experimental research on the propagation mechanisms of acoustic energy inside the pipeline to detect the leakage

Leakage from pipelines has negative impacts on property and environment. The diameters of internal acoustic detectors in pipelines are small and not easily blocked, making it suitable for pipelines under various working conditions. Studying the characteristics of pipeline leakage sound signal and the propagation mechanisms within pipelines is crucial for timely detection of small leaks. In this study, a 3D simulation model of pipeline leakage was established, and a CFD/CAA hybrid calculation method was used to obtain effective leakage flow field information via LES. The equivalent sound sources in the flow field were extracted based on the Lighthill acoustic analogy theory. Determine the characteristic frequency range of the leakage sound signal was 1–2 kHz. This study founded that an increase in the leakage pressure and aperture size both lead to an enhancement in the leakage sound signal, and the propagation of leakage sound signal in pipelines is affected by background flow. An experimental pipeline leakage system was designed, and the accuracy of the simulation results was verified experimentally.

Experimental timing and control using microcontrollers

Modern physics experiments rely on precise timing provided by programmable digital pulse generators. In many experimental control systems, this role is filled by custom devices built on field-programmable gate arrays. While highly flexible and performant, these devices can be difficult to scale to very large systems due to cost and complexity. Recent advances in microcontroller systems allow these much simpler devices to fill the role of digital pulse generators. Here, we demonstrate one such alternative based on the Raspberry Pi Pico microcontroller, which allows for timing resolution down to 7.5 ns with a minimum pulse width of 37.5 ns.