Saturation Behavior Research Articles

Soil Texture‐Based Parameterisation and Hydrological Insights of a Fully Coupled Surface and Subsurface Model at the Hubbard Brook Experimental Forest, USA

ABSTRACTParameterisation of fully coupled integrated hydrological models is challenging. The state‐of‐the‐art hydrogeology models rely on solutions of coupled surface and subsurface partial differential equations. Calibration of these models with traditional optimisation methods are not yet viable due to the high computational costs. Prior knowledge of the range of the parameters can be helpful as a starting point, however, due to natural variations, abstractions and conceptualizations used in modelling, a systematic exploration of the variable space is needed. In this study, we utilise the natural clustering of the soils based on their saturated and unsaturated hydraulic behaviour derived from soil texture maps in conjunction with two level Latin hypercube sampling to effectively explore model parameter spaces. Soil texture maps are similar to USDA soil classifications; however, the objective is to classify the soil based on their unsaturated behaviour, rather than soil texture. The method has never been utilised in the modelling and the results show that it can be applied to larger watersheds. The area of study is Hubbard Brook Experimental Forest, a northern hardwood forest in the White Mountains of New Hampshire, USA. An average Nash–Sutcliffe value of 0.80 is achieved for hourly discharge for the eight streams in the catchment. The Nash–Sutcliffe measure shows a 7% improvement with the addition of the snow melt and evapotranspiration parameters in the second stage. Exchange flux patterns vary seasonally in the catchment with largest infiltration occurring in spring.

In-vivo Raman microspectroscopy reveals differential nitrate concentration in different developmental zones in Arabidopsis roots

BackgroundNitrate (NO3−) is one of the two major forms of inorganic nitrogen absorbed by plant roots, and the tissue nitrate concentration in roots is considered important for optimizing developmental programs. Technologies to quantify the expression levels of nitrate transporters and assimilating enzymes at the cellular level have improved drastically in the past decade. However, a technological gap remains for detecting nitrate at a high spatial resolution. Using extraction-based methods, it is challenging to reliably estimate nitrate concentration from a small volume of cells (i.e., with high spatial resolution), since targeting a small or specific group of cells is physically difficult. Alternatively, nitrate detection with microelectrodes offers subcellular resolution with high cell specificity, but this method has some limitations on cell accessibility and detection speed. Finally, optical nitrate biosensors have very good (in-vivo) sensitivity (below 1 mM) and cellular-level spatial resolution, but require plant transformation, limiting their applicability. In this work, we apply Raman microspectroscopy for high-dynamic range in-vivo mapping of nitrate in different developmental zones of Arabidopsis thaliana roots in-situ.ResultsAs a proof of concept, we have used Raman microspectroscopy for in-vivo mapping of nitrate content in roots of Arabidopsis seedlings grown on agar media with different nitrate concentrations. Our results revealed that the root nitrate concentration increases gradually from the meristematic zone (~ 250 µm from the root cap) to the maturation zone (~ 3 mm from the root cap) in roots grown under typical growth conditions used for Arabidopsis, a trend that has not been previously reported. This trend was observed for plants grown in agar media with different nitrate concentrations (0.5–10 mM). These results were validated through destructive measurement of nitrate concentration.ConclusionsWe present a methodology based on Raman microspectroscopy for in-vivo label-free mapping of nitrate within small root tissue volumes in Arabidopsis. Measurements are done in-situ without additional sample preparation. Our measurements revealed nitrate concentration changes from lower to higher concentration from tip to mature root tissue. Accumulation of nitrate in the maturation zone tissue shows a saturation behavior. The presented Raman-based approach allows for in-situ non-destructive measurements of Raman-active compounds.

Tunneling Dielectric Thickness‐Dependent Behaviors in Transistors Based on Sandwiched Small Molecule and Insulating Layer Structures

AbstractThis work demonstrates the floating gate devices featuring a small molecule‐insulator‐small molecule‐insulator sandwiched structure, where the versatile electrical characteristics can be achieved depending on the thickness of the intermediate parylene tunneling dielectric layer (TDL). For the thin parylene layer of 15 nm (parallel DNTT channel transistor), channel also forms in the lower DNTT layer, allowing hole carriers to tunnel through the parylene TDL. The parallel DNTT channel transistor exhibits electrical characteristics similar to a conventional DNTT transistor with the increased contact resistance due to the presence of the intermediate parylene layer. When the parylene TDL is slightly thicker to be 45 nm, negative differential transconductance followed by current saturation behavior is observed, due to tunneling through the parylene TDL. Finally, photomemory is demonstrated with the sufficiently thick parylene layer (≈80 nm), where hole carriers injected from the electrode cannot tunnel through the parylene TDL, allowing the lower DNTT layer to act as a floating gate for the photogenerated charge carriers. This photomemory shows programmability under the light illumination with the specific wavelength as well as the robust retention and endurance characteristics. Furthermore, the photomemory has been successfully implemented on flexible paper substrates.

Unveiling the phases of bulk ZrTe5through magnetotransport phenomena.

We present a straightforward method which may greatly simplify and lower the threshold for determining the phase of the relatively enigmatic quantum material-ZrTe5. In this study, without directly probing the band structure, we identify the topological phase of the three-dimensional (3D) bulk ZrTe5crystal solely through low-temperature electrical and magnetotransport measurements. A two-dimensional (2D) weak antilocalization (WAL) effect was observed in our bulk ZrTe5crystal, along with clear Shubnikov-de Haas oscillations. The large prefactorαderived from WAL analyses indicates the presence of multiple conducting channels in the bulk ZrTe5crystal, where each channel is associated with individual 2D ZrTe5layers. It is the largeαvalue provides insights into the topological Dirac semimetal phase inherent to our ZrTe5crystal. Additionally, we analyze the pronounced linear magnetoresistance and saturation behavior under a perpendicular magnetic field. Our results suggest that bulk ZrTe5crystals, which exhibit unique layered transport features, serve as a promising platform for further research in quantum phases and transitions in 3D quantum systems.

Experimental Investigation of the Impact of Mixed Wettability on Pore-Scale Fluid Displacement: A Microfluidic Study.

Understanding rock wettability is crucial across various fields including hydrology, subsurface fluid storage and extraction, and environmental sciences. In natural subsurface formations like carbonate and shale, mixed wettability is frequently observed, characterized by heterogeneous regions at the pore scale that exhibit both hydrophilic (water-wet) and hydrophobic (oil-wet) characteristics. Despite its common occurrence, the impact of mixed wettability on immiscible fluid displacement at the pore scale remains poorly understood, creating a gap in effective modeling and prediction of fluid behavior in porous media. The primary objective of this study was to investigate how mixed wettability affects pore-scale fluid displacement dynamics, utilizing microfluidic devices designed to replicate rock-like structures with varied wettability properties. Current techniques for achieving mixed wettability within microfluidic devices often struggle with spatial control and resolution, limiting their accuracy. To address this limitation, a novel approach was employed that combined photolithography and molecular vapor deposition of perfluorodecyltrichlorosilane to precisely and selectively modify wettability within specific pore regions, achieving a mixed wettability distribution correlated with pore size for the first time. The experimental setup included five identical micromodels representing distinct wetting conditions, which were initially saturated with air and subsequently flooded by water. By systematically varying the ratio of hydrophilic to hydrophobic areas, we covered a range from fully hydrophilic to fully hydrophobic and intermediate mixed wettability configurations. Comparative displacement experiments revealed that pore-level mixed wettability has a pronounced effect on fluid displacement behavior, influencing the injection time, spatial invasion patterns, and dynamic pressure profiles. Results indicated that both the injection time and dynamic pressure decreased with an increase in the hydrophilic area fraction. Each wettability configuration displayed unique sequences of pore-filling events, emphasizing the critical role of the wettability distribution in influencing displacement dynamics. While mixed wettability exhibited a clear monotonic effect on invasion time and dynamic pressure, saturation behavior was notably nonmonotonic. Interestingly, mixed wettability scenarios with relatively medium to high hydrophilic fractions demonstrated enhanced overall sweep efficiency compared to the hydrophobic case and reduced the bypassed gas phase relative to the hydrophilic case. However, inefficiently distributed mixed wet zones were found to reduce the sweep efficiency. These findings highlight the critical influence of mixed wettability in fluid displacement processes, with significant implications for applications in oil recovery, CO2 sequestration, and other subsurface energy technologies.

Activation of tert-Butyl Hydroperoxide by Zr(IV) Stabilized by Polyoxotungstate Scaffolds.

Zr-monosubstituted polyoxometalates (Zr-POMs) of the Keggin (Bu4N)8[{PW11O39Zr(μ-OH)}2] (Zr-K), Lindqvist (Bu4N)6[{W5O18Zr(μ-OH)}2] (Zr-L), and Wells-Dawson (Bu4N)11H3[{P2W17O61Zr(μ-OH)}2] (Zr-WD) structures are capable of heterolytic activation of the environmentally benign oxidant tert-butyl hydroperoxide (TBHP) and catalyze epoxidation of alkenes and oxidation of alcohols to carbonyl compounds. Catalytic activity of corresponding Ti-POMs is much lower. Among Zr-POMs, Zr-K revealed higher epoxide yields. All Zr-POMs do not catalyze unproductive TBHP degradation, and epoxide yields with both aqueous and anhydrous TBHP are generally higher than with aqueous H2O2. Regioselectivity of the Zr-K-catalyzed limonene epoxidation with TBHP is different from that with H2O2: the more substituted and nucleophilic double bond is preferably epoxidized, pointing to an electrophilic oxygen transfer mechanism. The oxidation rates are first order in catalyst (Zr-K) and substrate (cyclooctene or cyclohexanol) and show a saturation behavior with increasing concentration of TBHP. Studies by HR-ESI-MS, ATR-FT-IR, and 31P NMR spectroscopic techniques implicated the formation of zirconium alkylperoxo species upon interaction of Zr-POMs with TBHP. HR-ESI-MS revealed the existence of monomeric and dimeric alkylperoxo complexes, [{PW11O39Zr}((CH3)3COO)]4- and [{PW11O39Zr((CH3)3COO)}2]8-, with predomination of the former, which is most likely the active species responsible for the selective oxidations.

Revisiting the Gas Diffusion Layer Water Inventory - from Micro to Macro Scale for Modern GDLs

Significant progress has been made over the last decade in improving Polymer Electrolyte Membrane fuel cells (PEMFC), resulting in usable current densities of up to 3.0 A/cm². Specifically for high current density values, it is important to maintain a well-balanced water inventory inside the fuel cell, particularly within the GDL, to prevent flooding of the porous material by excess product water and maintain high permeability for reactant gases. Twenty years ago, several authors conducted research [1,2,3,4] to enhance the modelling of permeability and wetting behavior of gas diffusion layers (GDLs) for PEMFC models. However, the standard Leverett J-function model [5], which was originally developed for porous rocks, remains the default description of saturation in many macro scale fuel cell models. Additionally, the latest GDL materials are much thinner and technologically advanced compared to that time. Thus, this work aims to model the water saturation and permeability of gases in modern GDLs using various simulation methods starting from the micro scale (GeoDict, Pore-Network-Modelling (PNM)). The micro-scale simulations are based on high-resolution X-ray scans of the GDL structure. These scans are analyzed and reconstructed with GeoDict to create digital twins that perform statistically identically and allow for virtual material modifications. Parametric studies for various local operating conditions are then performed using these twins, including e.g. different compression rates, temperatures, water production rates, and gas velocities. These simulations provide insight into the behavior of water saturation within the GDL structure and its influence on the diffusion of oxygen and hydrogen towards the catalyst layer. PNM modelling is employed to ensure the representativeness of the results regarding the macro-scale behavior of the porous material. Using the knowledge gained from the microstructure simulations, the simple Leverett J-function will be benchmarked. Depending on the results, ways to improve the J-function parameters or devising a new macro-scale functional description of the GDL water saturation and the resulting gas diffusion properties of the GDL will be explored.This work has received financial support by the German Federal Ministry for Digital and Transport within the GALLIA project (NIP II, 03B10114D).Citation:[1] Gostick, Jeffrey T., et al. "Capillary pressure and hydrophilic porosity in gas diffusion layers for polymer electrolyte fuel cells." Journal of power sources 156.2 (2006): 375-387.[2] Kumbur, E. C., K. V. Sharp, and M. M. Mench. "On the effectiveness of Leverett approach for describing the water transport in fuel cell diffusion media." Journal of Power Sources 168.2 (2007): 356-368.[3] Kumbur EC, Sharp KV, Mench MM. Validated Leverett approach for multiphase flow in PEFC diffusion media. J Electrochem Soc 2007;154. https://doi.org/10.1149/1.2784283.[4] Sarkezi-Selsky, Patrick, et al. "Lattice Boltzmann simulation of liquid water transport in gas diffusion layers of proton exchange membrane fuel cells: Parametric studies on capillary hysteresis." Journal of Power Sources 535 (2022): 231381. [5] Leverett, MoC. "Capillary behavior in porous solids." Transactions of the AIME 142.01 (1941): 152-169.

Gate Oxide Reliability in Silicon Carbide Planar and Trench Metal-Oxide-Semiconductor Field-Effect Transistors Under Positive and Negative Electric Field Stress

This work investigates the gate oxide reliability of commercial 1.2 kV silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs) with planar and trench gate structures. The performance of threshold voltage (Vth) and gate leakage current (Igss) in SiC MOSFETs is evaluated under positive and negative gate voltage stress. The oxide lifetimes of SiC planar and trench MOSFETs at 150 °C are measured using constant voltage Time-Dependent Dielectric Breakdown (TDDB) testing. From the test results, it is found that electron trapping and hole trapping in SiO2 caused by oxide electric field (Eox) stress affect the Vth of SiC MOSFETs. The saturation and turnaround behavior of the Vth shift during positive and negative gate voltage stresses indicates that the influence of charge trapping in the gate oxide varies with stress time. The Igss under positive and negative gate voltages depends on the tunneling barrier height for electrons and holes, respectively, which can be calculated using the Fowler–Nordheim (FN) tunneling mechanism. Moreover, the presence of near-interface traps (NITs) affects the barrier height for holes under negative gate voltages. The behavior of Vth shift and Igss under high-temperature gate bias reflects the charge trapping occurring in different regions of the gate oxide. In addition, compared to SiC planar MOSFETs, SiC trench MOSFETs with thicker gate oxide tend to exhibit higher lifetimes in TDDB tests.

Ultrafast terahertz conductivity in epitaxial graphene nanoribbons: an interplay between photoexcited and secondary hot carriers

Abstract Optical pump-terahertz probe spectroscopy has been used to investigate ultrafast photo-induced charge carrier transport in 3.4 µm wide graphene ribbons upon scaling the optical pump intensity. For low pump fluences, the deposited pump energy is rapidly redistributed through carrier–carrier scattering, producing secondary hot carriers: the picosecond THz photoconductivity then acquires a negative sign and scales linearly with an increasing pump fluence. At higher fluences, there are not enough equilibrium carriers able to accept the deposited energy, directly generated (excess) carriers start to contribute significantly to the photoconductivity with a positive sign leading to its saturation behavior. This leads to a non-monotonic variation of the carrier mobility and plasmonic resonance frequency as a function of the pump fluence and, at high fluences, to a balance between a decreasing carrier scattering time and an increasing Drude weight. In addition, a weak carrier localization observed for the polarization parallel to the ribbons at low pump fluences is progressively lifted upon increasing the pump fluence as a result of the rise of initial carrier temperature.

Fabrication and Characterisation of Kenaf Fibre Reinforced Polyamide Biocomposites for Railway Sleeper Applications

Railway passing traffic, speed, and load have significantly increased over the years, prompting industry stakeholders and researchers to seek an alternative sleeper material that can demonstrate its ability to potentially possess higher in-service bending resistance and be environmentally friendly and durable. To address these needs and due to environmental concerns, kenaf-reinforced polyamide has become of great importance. However, they could not be applied as railway track components because of the non-availability of their performance in this regard. In bridging this gap, this paper focused on fabricating and characterising six different formulations of treated kenaf fibre (TKF, 0–50% at 10% loading interval) reinforced polyamide biocomposites for railway sleeper applications. The result showed that the incorporation of TKF influenced the behaviour of the polyamide with respect to its water absorption, load-carrying capacity, and thermal stability. The result further demonstrated that the load-bearing capacity peaked at TKF 40 wt.%, surpassing conventional wooden and concrete sleepers. However, its water absorption (64-days saturation) behaviour increased significantly between 11%–21% as TKF rose from 10–50 wt.%, as expected due to TKF hydrophilic characteristics. On the other hand, TKF thermal stability was hampered beyond approximately 220°C for all TKF percentages. Kenaf fibre-reinforced polyamide biocomposites have demonstrated their potential for railway sleeper applications as their load-bearing capacity exceeded the minimum recommended AREMA specifications. Despite the milestone achieved, water absorption of kenaf fibre remained high. The development of sustainable and effective materials to meet the changing needs of contemporary railway infrastructure is greatly aided by the insights gained from this study.

Dimension-Dependent Nonlinear Optical Properties of Stanene Nanosheets.

Stanene (Sn)-based materials, with a graphene-like hexagonal structure, are now attracting considerable interest for potential applications in photoelectricity. However, the nonlinear optical properties of stanene remain largely unexplored. In this work, we prepared different sizes of stanene by liquid phase exfoliation and differential centrifugation methods, including two-dimensional (2D) Sn nanosheets (NSs) and zero-dimensional (0D) Sn nanodots (NDs). Z-scan measurements reveal that 2D Sn NSs exhibited high saturable absorption behavior, while the 0D Sn NDs led to reverse saturable absorption. Femtosecond ultrafast transient absorption spectra revealed that the reverse saturable absorption of Sn NDs is derived from a stronger excited state absorption and faster exciton relaxation dynamics. This research expands the potential applications of stanene in laser shielding and other ultrafast photonics technologies.

A germanium-vacancy center in diamond as single-photon source for radiometric application

Abstract We present the metrological characterization of a single-photon source based on a germanium-vacancy center in diamond under a solid immersion lens in a confocal microscope setup at room temperature. It was characterized in terms of the emission’s spectral distribution, single-photon purity, temporal stability and the emitter’s excited state lifetime and saturation behavior. An Allan deviation analysis was performed on the emission of the single-photon source to determine the optimal averaging time of the photon flux. The single-photon source was used for the relative calibration of the detection efficiency of two single-photon avalanche diode detectors. The results were compared with measurements using attenuated laser light for the calibration of the detectors.

Self – assembled aligned single – walled carbon nanotubes as an anisotropic polarizer and saturable absorber in erbium-doped femtosecond fiber laser

We report the production of a saturable absorber (SA) based on aligned single-walled carbon nanotubes SWCNTs by the self-assembly method. The ultrafast saturation behavior of prepared aligned and random nanostructures shows an increase of modulation depth by 6 % due to the alignment method. We also observed the dependence of aligned SWCNTs loss on the polarization direction of laser radiation. All-fiber Er-doped hybrid mode-locked fiber laser was demonstrated based on the aligned/random SWCNTs-based SAs. We achieved the generation of stable stretched pulses with a pulse duration of 490/569 fs and an average output power of 20.7/18.25 mW. We also investigated the advantages of using aligned SWCNTs compared to the typical structure with random tube distribution. We show that the use of aligned SWCNTs film increased the SNR by 24.5, decreased the mode-locking threshold power by 42 mW, and decreased the RIN level by (20–25) dB in the frequency range [∼0 Hz- 100 kHz] and ∼8 dB in the range [100 kHz–1 MHz].

Synthesis, growth and nonlinear optical properties of imidazolium hydrogen adipate monohydrate single crystal

A single crystal of Imidazolium Hydrogen Adipate Monohydrate (IHAM) has been obtained by the slow evaporation technique. The grown crystal belongs to the Triclinic crystal system. The spectral studies were further used to confirm the structure. The Hirshfeld analysis suggests that the major bonding in the crystal occurs through the Hydrogen atom constituting 69 % of the total bonding. The Void analysis shows a lower percentage of voids suggesting that the crystal is strongly packed. The optical constants such as optical and electrical conductivity, optical susceptibility and extinction coefficient were elucidated from the UV–Vis-NIR analysis. The refractive index of IHAM was determined to be 1.391 by the Prism Coupler. The work-hardening coefficient of the title compound was found to be 1.14 which classifies the material as hard. The hardness number shows the normal Indentation Size Effect (ISE). The electrical characteristics were studied by using the dielectric analyser. The solid-state parameters such as the Fermi gap, Penn gap and optical electronegativity were calculated based on the dielectric parameters. The electronic polarizability calculated by different methods is in mutual agreement. The TG/DTA analysis suggests that the material is suitable for applications up to 79 °C. The Z-Scan analysis confirms the Reverse Saturable Absorption behaviour. The third-order nonlinear susceptibility was calculated as 9.77×10−9 esu.

Solvent-free mechanosynthesis of Schiff bases derived from thiadiazole with potential application in sensing ionic species and NLO applications

In this work, we report the solvent-free mechanosynthesis of three Schiff bases (SBs) derived from 1,3,4-thiadiazole covalently bonded to indole (Th-In), quinoline (Th-Qn) and triphenylamine (Th-TPA) groups. This green chemistry method showed a drastic reduction in reaction time and avoidance of solvents for obtaining SBs, with good reaction yields. The molecular structures of SBs were investigated by computational chemistry calculations, with global reactivity parameters indicative of electron acceptor behavior, estimation of frontier molecular orbitals, and their theoretical band gaps of 3.49 and 3.4 eV for Th-In and Th-Qn, respectively, and the lowest of 299 eV for Th-TPA. To evaluate the possible NLO response, the hyperpolarizabilities (β) were also estimated, which are several orders of magnitude higher than the urea value used as a reference. The absorption and emission spectra were calculated using TD-DFT. These results showed a larger redshift for Th-TPA, with possible charge transfer processes more intense than those obtained for Th-In and Th-Qn. The photophysical properties of the Schiff bases were determined, with band gap values for Th-In, Th-Qn, and Th-TPA of 2.53, 2.66, and 2.39 eV in solution and 2.77, 2.26, and 2.21 eV in film, respectively. When the SBs were evaluated as potential naked-eye colorimetric chemosensors, colorimetric changes were observed in Fe2+, Fe3+, Pb2+, Cu2+, and Ag+ ions, with Ag+ being the most promising. Z-scan was used to evaluate the nonlinear response of the SBs and showed saturable absorber behavior with self-focusing processes. Cyclic voltammetry was used to determine the electrochemical band gaps, which were 2.70, 2.71, and 1.98 eV for Th-In, Th-Qn, and Th-TPA, respectively. Th-TPA exhibits superior optical and electrical properties among the three SBs investigated. In addition, it exhibits photochromism, which can be used in conjunction with its other properties in NLO and sensor applications.

Effect of Hydrogen Pressure on The Mass Transfer Characteristics of Hydrogen-Bromine Flow Battery Electrodes

The mass transfer characteristics of porous carbon electrodes in the liquid side of a hydrogen bromine redox flow battery (H2-Br2 RFB) were investigated under compressive deformation caused by operation at elevated hydrogen pressure. Here, flow cell measurements of permeability and micro-particle image velocimetry (μPIV), alongside electrochemical measurements of capacitance and battery discharge were used to characterize changes in the liquid side electrode compression, in-plane liquid flow, accessible surface area, polarization, and mass transfer scaling brought by hydrogen pressure. We studied two electrode types with different structures, carbon paper and carbon cloth, in untreated well as heat-treated forms in the pressure range 0–8 bar H2. It was found that pressure-induced compression of the liquid side electrode increases the accessible area of untreated electrodes, with little effect on heat-treated electrodes, but decreases the electrochemical performance of the battery in all cases by increasing the ohmic resistance of the cell and decreasing the mass transfer coefficient of the porous electrode. Overall, heat treatment is shown to affect the rigidity, saturation behavior, and generalized mass transfer of paper electrodes but not of cloth electrodes. Our findings will guide the selection of electrode materials and operation parameters for the H2-Br2 RFB.

On the Role of Physical Processes in Controlling Equatorial Plasma Bubble Morphology

AbstractIn this study, we present the results of an analysis of the morphological features of Equatorial Plasma Bubbles (EPBs) over South America. In this context, we analyzed data from the Disturbance Ionosphere indeX (DIX) maps calculated using around 450 Global Navigation Satellite System (GNSS) stations. To mitigate the influence of magnetic disturbances on bubble development, only data from geomagnetically quiet days were utilized. This study covered the period from the post‐peak of solar cycle 24 (2015) to the pre‐peak of solar cycle 25 (2023), totaling 1321 nights with EPB occurrences, representing the largest data set of EPBs ever compiled for South America. Our analysis unveiled several key findings regarding EPBs and their behavior over the South American region. First, we observed that the amplitude of plasma depletions, as reflected in the DIX values, and the EPB latitudinal development follow an approximately 11‐year cycle driven by solar radiation levels. Furthermore, our analysis highlights the significant influence of factors such as the angle between the solar terminator and the magnetic meridian (T‐M angle), which varies inversely with the vertical plasma drift velocity during the pre‐reversal enhancement (PRE). Additionally, we discuss the longitudinal variations associated with magnetic declination, as well as the saturation behavior of EPB development with extreme solar flux.

Analysis of hysteresis loops and dielectric performance in the ovalene-like system: Monte Carlo study

This Monte Carlo study offers a comprehensive analysis of the ovalene-like system, emphasizing its dielectric behavior, thermal performance and hysteresis loops. The investigation reveals intricate dynamics influenced by diverse parameters, contributing to a nuanced understanding of the system’s response. Additionally, the study scrutinizes the impact of various physical parameters on the thermal behavior of polarizations and susceptibilities. The examination thoroughly explores the influence of these parameters on loop characteristics, coercive field, and saturation behavior, unveiling the formation of multiple loops and polarization plateaus on the electric hysteresis. In summary, this study advances our understanding of the ovalene-like system’s dielectric response, thermal characteristics and hysteresis dynamics, providing valuable insights for future research and applications, particularly in advanced electronic devices.

A Semi-Mechanistic Physiologically Based Biopharmaceutics Model to Describe Complex and Saturable Absorption of Metformin: Justification of Dissolution Specifications for Extended Release Formulation.

Physiologically based pharmacokinetic (PBPK) or physiologically based biopharmaceutics models (PBBM) demonstrated plethora of applications in both new drugs and generic product development. Justification of dissolution specifications and establishment of dissolution safe space is an important application of such modeling approaches. In case of molecules exhibiting saturable absorption behavior, justification of dissolution specifications requires development of a model that incorporates effects of transporters is critical to simulate in vivo scenario. In the present case, we have developed a semi-mechanistic PBBM to describe the non-linearity of BCS class III molecule metformin for justification of dissolution specifications of extended release formulation at strengths 500mg and 1000mg. Semi-mechanistic PBBM was built using physicochemical properties, dissolution and non-linearity was accounted through incorporation of multiple transporter kinetics at absorption level. The model was extensively validated using literature reported intravenous, oral (immediate & extended release) formulations and further validated using in-house bioequivalence data in fasting and fed conditions. Virtual dissolution profiles at lower and upper specifications were generated to justify the dissolution specifications. The model predicted literature as well as in-house clinical study data with acceptable prediction errors. Further, virtual bioequivalence trials predicted the bioequivalence outcome that matched with clinical study data. The model predicted bioequivalence when lower and upper specifications were compared against pivotal test formulations thereby justifying dissolution specifications. Overall, complex and saturable absorption pathway of metformin was successfully simulated and this work resulted in regulatory acceptance of dissolution specifications which has ability to reduce multiple dissolution testing.

Approaching the Intrinsic Limits of Short Channel Vertical Organic Electrochemical Transistors.

Vertical architectures for organic electrochemical transistors (OECTs), due to their submicrometer channel lengths, have presented themselves as a straightforward design approach for achieving high gm/τ ratios, a figure of merit that assesses the performance of the devices by virtue of their transconductance (gm = dID/dVGS) and switching time constant (τ). However, as the practical limitations of the geometries are overcome, the influence of parasitic phenomena becomes more dominant and limits the performance of the device. One approach to reduce the detrimental effects of parasitic resistance in the drain-source circuit is to use a four-point sourcing technique. Here, vertical OECTs are fabricated with four-point structures to approach the intrinsic limit of these devices. It is shown that this approach improves the saturation behavior of the devices, closing the gap between measured gm and intrinsic transconductance gmi at their peak values. Overall, the results discussed here provide insight into the effects of parasitic resistance on OECTs, which in contrast to field-effect transistors, are not as extensively documented.