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The synthesis of Mn 3 O 4 nanoparticles and activated carbon/reduced graphene oxide (AC/rGO) nanocomposite involved surfactant-assisted chemical precipitation and sonochemical methods, respectively, to produce high-quality electrode materials. The morphology of the spherical Mn 3 O 4 nanoparticles and the wrinkled sheet-like structure of rGO were found to enhance the electrochemical performance and stability of the electrodes significantly. Electrochemical investigations were conducted using two electrolytes: 2 M KOH and LiNO 3 . In half-cell analyses, Mn 3 O 4 and AC/rGO exhibited specific capacitances of 138 F g −1 and 609 F g −1 , respectively, with 2 M KOH, and 104 F g −1 and 49.8 F g −1 with 2 M LiNO 3 electrolyte, at 1 A g −1 . The observed differences in performance were discussed regarding ionic radius, ionic conductivity, and diffusional coefficient of ions. Furthermore, asymmetric supercapacitor pouch cell devices (Mn 3 O 4 //AC/rGO, MAGASC) were fabricated employing both electrolytes, demonstrating enhanced electrochemical performance. The MAGASC pouch cells exhibited specific capacitances of 273 F g −1 and 130 F g −1 at. 100 mV s −1 with KOH and LiNO 3 electrolytes, respectively. Energy and power density were measured to be 35.2 Wh kg −1 and 1.4 kW kg −1 for KOH electrolyte, and 10.9 Wh kg −1 and 1.6 kW kg −1 for LiNO 3 electrolyte at 0.6 A g −1 . Electrochemical impedance spectroscopy (EIS) analysis revealed a lower equivalent series and charge transfer resistance for MAGASC with KOH electrolyte than for ASC pouch cells with LiNO 3 electrolyte. Complex capacitance and relaxation time constant of the MAGASC were determined using EIS data to analyze frequency behavior. Moreover, the ASC pouch cell demonstrated excellent cyclic stability, retaining 90% of its initial capacitance over 5000 cycles in both electrolytes. These findings underscore the superior energy storage capacity of MAGASC with KOH electrolyte and its broader operating potential with LiNO 3 electrolyte. Graphical Abstract

In this paper, a discontinuous Galerkin (DG) time stepping method combined with the standard finite element method in space is proposed to solve a class of semilinear parabolic differential equations with time constant delay. The time semi-discretization and the relevant global convergence of the DG solution under suitable uniform meshes are derived. The standard Galerkin method in space is used to obtain the fully discrete scheme and the optimal global convergence of the full discretization is presented. Numerical experiments for one-dimensional and two-dimensional equations are provided to demonstrate the theoretical results.

Background Transepidermal water loss (TEWL) is often used as an index for skin barrier function. The skin barrier tester, SBT‐100 (Rousette Strategy Inc), measures the TEWL, water evaporation time, and time constant by contacting the skin and diffusing water into the closing measurement chamber. However, the relationship between the TEWL and time constant has not been sufficiently investigated. This study involved analyzing the underlying measurement principle and obtaining data through two experiments. Materials and methods The TEWL and time constant were measured using SBT‐100. Experiment 1 produced a simple simulation model for continuous water evaporation from the skin using a moisture‐permeable film. In experiment 2, four skin sites of 43 healthy volunteers were examined from May to September 2018. Results In experiment 1, the TEWL increased and time constant decreased, following an increase in humidity in the external environment. Both parameters demonstrated significant negative correlation (drying: ρ = −0.832, p < 0.001). For the 43 healthy volunteers who participated in experiment 2, their TEWL increased and time constant decreased in summer. For all skin measurement sites, both data demonstrated significant negative correlation (forehead: ρ = −0.909, p < 0.001; back of the left hand: ρ = −0.829, p < 0.001; left lateral elbow: ρ = −0.896, p < 0.001; left lateral malleolus: ρ = −0.865, p < 0.001). Conclusion Results indicated that the time constant is significantly correlated with TEWL. Furthermore, the time constant can be used as a parameter for evaluating skin barrier function.

Motion sickness (MS) is a common physiological response that often occurs when individuals are exposed to environments with repeated acceleration stimuli. MS results from a mismatch between the vestibular system and visual and proprioceptive inputs. As a crucial organ for sensing acceleration stimuli, the vestibular system is closely related to the onset of MS. However, the complex pathogenesis of MS has led to its diagnosis primarily relying on subjective questionnaires, with a lack of objective indicators for evaluation. To identify objective indicators for evaluating MS, we conducted rotating chair stop experiments based on the principle of vestibulo-ocular reflex with 65 volunteers, obtaining their nystagmus slow-phase velocity and related time constants. Additionally, we conducted detailed MS questionnaires with these volunteers to assess their MS susceptibility. Through correlation analysis, we explored whether the nystagmus slow-phase velocity and related time constants significantly correlated with the MS questionnaire scores. The results showed significant positive correlations between the maximal nystagmus slow-phase velocity, cupula time constant, velocity storage time constant, and the nystagmus duration with the MS questionnaire scores in the 65 volunteers. These results indicated that these nystagmus parameters could serve as objective indicators for assessing MS susceptibility. Using K-Means clustering analysis, we classified MS susceptibility into categories I, II, III, and IV, and conducted K-Means clustering analysis on the corresponding nystagmus slow-phase velocity, cupula time constant, velocity storage time constant, and nystagmus duration. The magnitude and range of these indicators at different levels was quantified, offering objective and quantitative indicators for the clinical diagnosis of MS.

Viscoelasticity of the soft tissue is an important mechanical factor for disease diagnosis, biomaterials testing and fabrication. Here, we present a real-time and high-resolution viscoelastic response-optical coherence elastography (VisR-OCE) method based on acoustic radiation force (ARF) excitation and optical coherence tomography (OCT) imaging. The relationship between displacements induced by two sequential ARF loading—unloading and the relaxation time constant of the soft tissue—is established for the Kelvin-Voigt material. Through numerical simulation, the optimal experimental parameters are determined, and the influences of material parameters are evaluated. Virtual experimental results show that there is less than 4% fluctuation in the relaxation time constant values obtained when various Young’s modulus and Poisson’s ratios were given for simulation. The accuracy of the VisR-OCE method was validated by comparing with the tensile test. The relaxation time constant of phantoms measured by VisR-OCE differs from the tensile test result by about 3%. The proposed VisR-OCE method may provide an effective tool for quick and nondestructive viscosity testing of biological tissues.

Several studies on solar cells using SCAPS-1D were conducted to investigate their performance, which are typically limited to I–V analysis for DC characterization. Therefore, in the present study, a very wide frequency range from 10–2 Hz to 1012 Hz was employed to explore diffusion processes and investigate the performance of lead-free Perovskite Solar Cells (PSCs) featuring as a novel heterostructure. These investigations concern the optimization of MASnI3 thickness as an absorber. Additionally, the impact of series (Rs) and shunt (Rsh) resistances is also examined. From the I–V analysis, it was determined that the power efficiency (PCE) could be achieved at a thickness of 0.6 µm. Increasing the series resistance (Rs) led to a significant decrease in the fill factor (FF) and (PCE), whereas the shunt resistance (Rsh) demonstrated a notable improvement in both (FF) and (PCE). Analysis of AC characteristics revealed complex impedance (Z*) and modulus (M*) indicative of main ionic transport, recombination, and diffusion processes crucial for optimization. An appropriate equivalent circuit model was developed and validated through deconvolution and theoretical considerations, yielding parameters such as the time constant for each process. It was observed that ionic conductivity and electronic diffusion play key roles in balancing charge collection and recombination losses. The critical influence of series and shunt resistance on low and high-frequency processes was emphasized, underscoring their significance in solar cell efficiency. A strong correlation was established between the evolution of time constants for each process and power conversion efficiency (PCE).

The ability of cortical networks to integrate information from different sources is essential for cognitive processes. On one hand, sensory areas exhibit fast dynamics often phase-locked to stimulation; on the other hand, frontal lobe areas with slow response latencies to stimuli must integrate and maintain information for longer periods. Thus, cortical areas may require different timescales depending on their functional role. Studying the cortical somatosensory network while monkeys discriminated between two vibrotactile stimulus patterns, we found that a hierarchical order could be established across cortical areas based on their intrinsic timescales. Further, even though subareas (areas 3b, 1, and 2) of the primary somatosensory (S1) cortex exhibit analogous firing rate responses, a clear differentiation was observed in their timescales. Importantly, we observed that this inherent timescale hierarchy was invariant between task contexts (demanding vs. nondemanding). Even if task context severely affected neural coding in cortical areas downstream to S1, their timescales remained unaffected. Moreover, we found that these time constants were invariant across neurons with different latencies or coding. Although neurons had completely different dynamics, they all exhibited comparable timescales within each cortical area. Our results suggest that this measure is demonstrative of an inherent characteristic of each cortical area, is not a dynamical feature of individual neurons, and does not depend on task demands.

The time constant of the cerebral arterial bed (τ) represents an estimation of the transit time of flow from the point of insonation at the level of the middle cerebral artery to the arteriolar-capillary boundary, during a cardiac cycle. This study assessed differences in τ among healthy volunteers across different age groups. Simultaneous recordings of transcranial Doppler cerebral blood flow velocity (CBFV) and arterial blood pressure (ABP) were performed on two groups: young volunteers (below 30 years of age), and older volunteers (above 40 years of age). τ was estimated using mathematical transformation of ABP and CBFV pulse waveforms. 77 healthy volunteers [52 in the young group, and 25 in the old group] were included. Pulse amplitude of ABP was higher [16.7 (14.6–19.4) mmHg] in older volunteers as compared to younger ones [12.5 (10.9–14.4) mm Hg; p < 0.001]. CBFV was lower in older volunteers [59 (50–66) cm/s] as compared to younger ones [72 (63–78) cm/s p < 0.001]. τ was longer in the younger volunteers [217 (168–237) ms] as compared to the older volunteers [183 (149–211) ms; p = 0.004]. τ significantly decreased with age (rS =  − 0.27; p = 0.018). τ is potentially an integrative marker of the changes occurring in cerebral vasculature, as it encompasses the interplay between changes in compliance and resistance that occur with age.

In humans, physical exercise imposes narrower limits for the heart rate (fH) response of the baroreflex, and vascular modulation becomes largely responsible for arterial pressure regulation. In undisturbed reptiles, the baroreflex-related fH alterations at the operating point (Gop) decreases at elevated body temperatures (Tb) and the vascular regulation changes accordingly. We investigated how the baroreflex of rattlesnakes, Crotalus durissus, is regulated during an activity at different Tb, expecting that activity would reduce the capacity of the cardiac baroreflex neural pathway to buffer arterial pressure fluctuations while being compensated by the vascular neural pathway regulation. Snakes were catheterized for blood pressure assessment at three different Tb: 15, 20 and 30 °C. Data were collected before and after activity at each Tb. Baroreflex gain (Gop) was assessed with the sequence method; the vascular limb, with the time constant of pressure decay (τ), using the two-element Windkessel equation. Both Gop and τ reduced when Tb increased. Activity also reduced Gop and τ in all Tb. The relationship between τ and pulse interval (τ/PI) was unaffected by the temperature at resting snakes, albeit it reduced after activity at 20 °C and 30 °C. The unchanged τ/PI and normalized Gop at different Tb indicated those variables are actively adjusted to work at different fH and pressure conditions at rest. Our data suggest that during activity, the baroreflex-related fH response is attenuated and hypertension is buffered by a disproportional increase in the rate which pressure decays during diastole. This compensation seems especially important at higher Tb where Gop is already low.

The time constant selected for lock-in amplification (LIA) has a crucial impact on observed line shapes in laser heterodyne spectroscopy, in particular in the case of ground-based remote monitoring of trace gas in the atmospheric column using laser heterodyne radiometer (LHR). Conventional simulation could not allow validation of LHR spectra measured in a real and complex atmospheric environment exhibiting large temporal and spatial variability (humidity, temperature, pressure, etc) that impact significantly the measured LHR spectra profiles. High-precision spectral measurement is thus crucial to avoid any spectral distortion resulting from the measurement. In this paper, the impact of LIA time constant on spectral line shape is investigated for LHR operating in continuous laser tuning mode, based on analysis of laboratory heterodyne spectra, in terms of signal-to-noise ratio (SNR), line width broadening, absorption depth and line shift. With respect to the given frequency scanning speed in continuous mode and to the halfwidth of the absorption feature to scan, a reasonable scanning time ΔTscan, the time needed for scanning laser frequency through the halfwidth ΔνHWHM of the absorption line, equal to or longer than 14 times of the LIA time constant τ is concluded in order to efficiently reduce the noise while without significant shift and distortion of the line shape. Experimental validation was carried out using a laser heterodyne absorption spectroscopy approach in the laboratory. Four different combinations of time constants τ and scanning time ΔTscan were used to record heterodyne spectra of a CH4 absorption line near 1242.00 cm−1 in continuous laser tuning mode. An optimal combination of a scanning time of 137 ms with a time constant of 1 ms was obtained. This optimal combination was used for ground-based measurements of CH4 and N2O in the atmospheric column by LHR. The extracted LHR spectrum is in good agreement with a referenced TCCON (Total Carbon Column Observing Network) FT-IR (Fourier-transform infrared) spectrum.