Electron Flow Research Articles

Signature of Proton-Hole Transfer in Hydrogen-Bonded Solids at 10 K.

Although proton transport in water ice is well understood, proton-hole transfer (PHT) involving proton abstraction by anions remains less explored. This study investigates PHT in H2S and NH3 solids at low temperatures, aiming to determine whether these solids exhibit negative charge transport similar to that in ice. In H2S and NH3 solids at 10 K, surface HS- and NH2- anions in hydrogen-bonded systems trigger negative current flow, providing a clear signature of PHT. This negative current is controlled by electron flow and 193 nm ultraviolet irradiation, which generates HS- and NH2- anions on the solid surfaces. In bilayer H2S/H2O and NH3/H2O solids, a significant negative current is observed only in the NH3/H2O solid, which is attributed to the exothermic proton abstraction by NH2- from H2O at the bilayer interface, a process not available for H2S on ice. This study is the first to demonstrate PHT-induced electrochemical behavior in hydrogen-bonded solids other than ice.

Spin injection from a magnetically near-compensated state in GdFeCo and inverse spin Hall effect in electron-hole compensated metal YH2.

Rare-earth-transition-metal (RE-TM) ferrimagnets are excellent materials for spin encode/decode operations via spin transport in nonmagnetic regions. This superior performance stems from two key factors. First, the antiferromagnetic coupling between RE4f and TM3d sublattices reduces both the spin-transfer-torque switching time and inter-device magnetic-coupling. Second, the RE-TM ferrimagnets function as spin injectors/ejectors, with the TM3d sublattice solely responsible for carrier spin polarization (p), similar to conventional ferromagnetic metals. We performed spin transport experiments using the sign change of p in RE-TM, which exhibits a positive value above the magnetization compensation temperature and a negative value below it. We measured temperature dependencies of the transverse resistances (RT) of electron-hole compensated metal YH2under out-of-plane spin-polarized current injection/ejection from GdFeCo (Gd:Fe:Co=25:66:9). The abrupt change in loop polarity of the out-of-plane field dependence of RT in YH2between 290 and 300 K, which aligns with the out-of-field curve of the polar Kerr rotation in GdFeCo electrodes, strongly suggests that the observed RT results from the inverse spin Hall effect (ISHE) in YH2. We analytically formulated ISHE in terms of the electron and hole spin currents injected from the spin sources, enabling regression analysis to assess the spin transport characteristics of a GdFeCo/YH2/GdFeCo magnetic double heterostructure. To explain the observed Hall voltages, enhancements in both the spin diffusion length of YH2and the spin injection efficiency are necessary.&#xD.

Row hammer-induced D0 failure improvement in sub-20 nm DRAM using air gap

Abstract As the density of bit cells increases, reliability issue in state-of-the-art Dynamic Random Access Memory (DRAM) becomes critical. Row Hammer (RH) is one of the reliability issues in sub-20 nm DRAM product. This work proposes an air gap technique [i.e., placing an air gap beneath passing wordline (PWL)], to suppress the RH in sub-20 nm DRAM. Using 3D TCAD simulations, the electric field and Shockley-Read-Hall (SRH) recombination rate are investigated when the PWL is activated. And, when the PWL is deactivated, the leakage current toward the bitline is extracted, to investigate the impact of the air gap on RH. It turned out that a low-k dielectric material in the air gap can effectively help to reduce the electric field intensity near the interface between shallow-trench-isolation (STI) and silicon. The relatively weak electric field can prevent the flow of electrons that causes read/write errors through trap-assisted recombination. By adopting the air gap in STI, 82 % improvement was estimated in terms of alleviating RH.

Mitochondria‐Targeted Photoredox Catalysis Activates Pyroptosis for Effective Tumor Therapy

AbstractThe development of biocompatible and efficient photocatalytic redox systems to mimic bio‐photoreactors in living cells holds great potential for manipulating intracellular biochemical reaction processes and thus advancing tumor therapy. In this study, a mitochondria‐targeted photoredox catalyst, 2D vacancy‐rich molybdenum oxide nanosheets (Mt‐VR‐MoO3) is presented. These nanosheets possess a high density of oxygen vacancies (19.2%) and exhibit strong photocatalytic redox activity under near‐infrared (NIR) light. Following a two‐step functionalization, Mt‐VR‐MoO3 effectively disrupts mitochondrial electron flow in an oxygen‐independent manner upon irradiation with second near‐infrared (NIR‐II) light. This targeted disruption leads to on‐demand induction of substantial damage to tumor cell mitochondria, characterized by increased production of mitochondrial reactive oxygen species (mtROS) and the release of cytochrome c (Cyt c), which collectively trigger the pyroptosis of cancer cells. The approach achieved tumor‐targeted photocatalytic eradication with high efficacy (tumor growth inhibition rate of 86.9%) in an orthotopic breast 4T1 murine tumor model, with no observable harm to normal organs. These findings provide inspiration for manipulating intracellular biochemical reactions using artificial photocatalytic materials, paving the way for pyroptosis activation as a promising approach in tumor therapy.

A Bifurcated Reconnecting Current Sheet in the Turbulent Magnetosheath

We report the Magnetospheric Multiscale (MMS) observation of a bifurcated reconnecting current sheet in Earth’s dayside magnetosheath. Typical signatures of the ion diffusion region, including sub-Alfvénic demagnetized ion outflow, super-Alfvénic electron flows, Hall magnetic fields, electron heating, and energy dissipation, were found when MMS traversed the current sheet. The weak ion exhaust at the current sheet center was bounded by two current peaks in which super-Alfvénic electron flow directed toward and away from the X line were observed, respectively. Both off-center current peaks were primarily carried by electrons, one of which was supported by field-aligned current, while the other was mainly supported by current driven by electric field drift. The two current peaks also exhibit other differences, including electron heating, electron pitch angle distributions, electron nongyrotropy, energy dissipation, and magnetic field curvature. An ion-scale magnetic flux rope was detected between the two current peaks where electrons showed field-aligned bidirectional distribution, in contrast to field-aligned distribution parallel to the magnetic field in two current peaks. The observed current sheet was embedded in a background shear flow. This shear flow worked together with the guide field and asymmetric field and density to affect the electron dynamics. Our results reveal the reconnection properties in this special plasma and field regime which may be common in turbulent environments.

Simple Teaching Tools: Efforts to Improve Mastery of Direct Current Electrical Materials by Utilization in Physics

A teaching tool is a collection of concrete objects that are purposefully developed or created to make the learning process more relevant and effective. Our findings at one of Ambon City’s high schools revealed that there were no teaching tools for direct current (DC) power. Hence, learning has only been accomplished via the lecture technique. This impacted students’ poor mastery of the material. This study aimed to improve mastery of the DC electricity topic using basic teaching methods in physics education. This type of study consists of a one-group pre and post-test. Data were examined with N-Gain to measure the increase in mastery of the subject after students completed the learning procedure. The research sample consisted of 22 students from Class XII-3. According to the study’s findings, 45.5% of students with high qualifications and 54.5% of students with medium qualifications improved their mastery of the material under study. Thus, it is possible to conclude that the use of simple teaching tools in DC electricity material in physics education can improve students’ comprehension of the topic at hand. Keywords: simple teaching tools, material mastery, direct current electricity

Processes independent of nonphotochemical quenching protect a high-light-tolerant desert alga from oxidative stress.

Non-photochemical quenching (NPQ) mechanisms are crucial for protecting photosynthesis from photoinhibition in plants, algae, and cyanobacteria, and their modulation is a long-standing goal for improving photosynthesis and crop yields. The current work demonstrates that Chlorella ohadii, a green micro-alga that thrives in the desert under high light intensities that are fatal to many photosynthetic organisms does not perform nor require NPQ to protect photosynthesis under constant high light. Instead of dissipating excess energy, it minimizes its uptake by eliminating the photosynthetic antenna of photosystem II. In addition, it accumulates antioxidants that neutralize harmful reactive oxygen species (ROS) and increases cyclic electron flow around PSI. These NPQ-independent responses proved efficient in preventing ROS accumulation and reducing oxidative damage to proteins in high-light-grown cells.

Highly Reversible Sodium Metal Batteries Enabled by Extraordinary Alloying Reaction of Single‐Atom Antimony

AbstractThe unique coordination configuration of single‐atom materials (SAMs) allows precise reaction control at atomic‐level and a potential of unusual electrochemical reaction. Nevertheless, it is a big challenge to prepare main group element with high loading content. Here, multifield‐regulated synthesis (MRS) technology is utilized to rapidly produce single‐atom antimony (Sb) metal with a high loading of 15 wt.%. Ab initio molecular dynamics simulations reveal the significantly enhanced reaction kinetics of Sb and nitrogen‐doped graphene by multi‐physics field coupling. Compared with common metallic Sb nanoparticles, atomically dispersed Sb displays remarkably improved electrochemical reaction kinetics and stable structure due to the negligible variation of stresses and volume expansion during the pseudocapacitive alloying‐dealloying process. Such extraordinary alloying reaction in well‐dispersed Sb atoms enabling homogeneous ion flow can serve as active nucleation sites for regulating even Na metal nucleation and growth. As a result, copper foil coated with only ≈3 µm thickness of such material exhibits a high Coulombic efficiency of up to 99.99%, an ultra‐low overpotential of 3 mV, and a long lifetime exceeding 2500 h in symmetrical cells. Furthermore, an anode‐free MRS‐SbSA||Na3V2(PO4)3 battery is constructed, which demonstrates exceptionally high energy density (≈362 Wh Kg−1), outstanding rate capability and good cycling stability.

Magnetic Fields Generated by Directed Ionic Flow

Magnetic Fields Generated by Directed Ionic Flow

Mitochondrial dynamics and bioenergetics in Alzheimer's induced pluripotent stem cell-derived neurons.

Mitochondrial (MT) dysfunction is a hallmark of Alzheimer's Disease (AD), but the scope and severity of these specific deficits across forms of AD are not well characterized. We designed a high-throughput, longitudinal, phenotypic assay to track MT dynamics and bioenergetics in glutamatergic iPSC-derived human neurons possessing mutations in presenilin 1 (PSEN1), presenilin 2 (PSEN2) and the amyloid beta precursor protein (APP). Each gene set was comprised of iPSC-derived neurons from an AD patient as well as two to three engineered mutations with appropriate isogenic and age matched controls. These iPSC-derived neurons were imaged every other day beginning at DIV10 to assess how MT length and content change over a ten day time course using a mitochondrially targeted reporter. A second cytosolic reporter allowed for visualization of neurites. Bioenergetics assays, focusing on MT respiration and individual electron transport chain (ETC) complexes, were also surveyed over this time course. Mutations in all three genes altered MT function measured by basal, ATP-linked, and maximal oxygen consumption rate; and spare respiratory capacity, with PSEN1/PSEN2 alleles being more severe than APP mutations. Electron flow through Complexes I-IV was decreased in PSEN1/PSEN2 mutations but; in contrast, APP alleles had only modest impairments of Complexes I and II. We measured aspects of MT dynamics, including fragmentation, and neurite degeneration, both of which were dramatic in PSEN1/PSEN2 alleles, but essentially absent in APP alleles. The marked differences in MT pathology may occur from the distinct ways amyloids are processed into amyloid beta peptides (Aβ) and may correlate with the disease severity.

Sodium-Selective Channelrhodopsins

Channelrhodopsins (ChRs) are light-gated ion channels originally discovered in algae and are commonly used in neuroscience for controlling the electrical activity of neurons with high precision. Initially-discovered ChRs were non-selective cation channels, allowing the flow of multiple ions, such as Na+, K+, H+, and Ca2+, leading to membrane depolarization and triggering action potentials in neurons. As the field of optogenetics has evolved, ChRs with more specific ion selectivity were discovered or engineered, offering more precise optogenetic manipulation. This review highlights the natural occurrence and engineered variants of sodium-selective channelrhodopsins (NaChRs), emphasizing their importance in optogenetic applications. These tools offer enhanced specificity in Na+ ion conduction, reducing unwanted effects from other ions, and generating strong depolarizing currents. Some of the NaChRs showed nearly no desensitization upon light illumination. These characteristics make them particularly useful for experiments requiring robust depolarization or direct Na+ ion manipulation. The review further discusses the molecular structure of these channels, recent advances in their development, and potential applications, including a proposed drug delivery system using NaChR-expressing red blood cells that could be triggered to release therapeutic agents upon light activation. This review concludes with a forward-looking perspective on expanding the use of NaChRs in both basic research and clinical settings.

Performance of ITER pressure gauges during deuterium operation in the Large Helical Device

Abstract During deuterium campaigns on the heliotron large helical device (LHD), ITER pressure gauges with different cathode materials were used to measure the neutral pressure in the sub-divertor region. Throughout these campaigns, it was observed that the performance of the LaB6 cathodes was unsatisfactory, credited to the generation of neutrons impacting the gauges. Conversely, measurements taken with pressure gauges with a ZrC cathode performed well throughout the deuterium pulses. The ITER pressure gauge with the ZrC cathode could be operated with a very high electron current of 800 µA, thus improving the lower detection limit of the neutral pressure in LHD. With this design it was also possible to avoid jumps in the ion current within strong magnetic fields, improving the accuracy of the measurement from 15% uncertainty to 5%. These features allowed very precise neutral pressure measurements to be made in a fusion device with magnetic confinement. The total running time in the magnetic field was around 60 hours, less than the cathode life time of 350 hours.

Antisecretory Factor 16 (AF16): A Promising Avenue for the Treatment of Traumatic Brain Injury—An In Vitro Model Approach

Traumatic brain injury (TBI) is caused by an external mechanical force to the head, resulting in abnormal brain functioning and clinical manifestations. Antisecretory factor (AF16) is a potential therapeutic agent for TBI treatment due to its ability to inhibit fluid secretion and decrease inflammation, intracranial pressure, and interstitial fluid build-up, key hallmarks presented in TBI. Here, we investigated the effect of AF16 in an in vitro model of neuronal injury, as well as its impact on key components of the autophagy pathway and mitochondrial dynamics. N2Awt cells were treated with AF16, injured using a scratch assay, and analysed using confocal microscopy, correlative light and electron microscopy (CLEM), flow cytometry, and western blotting. Our results reveal that AF16 enhances autophagy activity, regulates mitochondrial dynamics, and provides protection as early as 6 h post-injury. Fluorescently labelled AF16 was observed to localise to lysosomes and the autophagy compartment, suggesting a role for autophagy and mitochondrial quality control in conferring AF16-associated neuronal protection. This study concludes that AF16 has potential as a therapeutic agent for TBI treatment through is regulation of autophagy and mitochondrial dynamics.

A De Novo Auto-Activated Solar-Driven Biohybrid System for Hydrogen Production in Methanotrophic Cells.

Climate change driving by greenhouse gas emissions from petroleum-based energy has garnered significant attention. Renewable energy production via a sustainable system that integrates the cell factory and visible-light-driven photocatalysts offers a novel approach for upcycling methane and addressing global energy challenges. Here, an auto-activated biohybrid system driven by solar energy is developed for converting methane into hydrogen fuel, which incorporated thienoviologen (S-MV2+) and genetically engineered methanotrophic bacteria. In this system, S-MV2+ functioned as photosensitizer and electron mediator, capturing solar energy and supplying electrons for an enzyme-catalyzed bioprocess. The genetically modified Methylomicrobium buryatense 5GB1 mutant, lacking methanol dehydrogenase but overexpressing hydrogenase, is able to convert methane into methanol that maintains the electron flow cycle by quenching photogenerated holes for both hydrogen biosynthesis and methane oxidation. Finally, the highest H2 production of 272.96 µM from this biohybrid system was achieved with methanol as a sacrificial agent generated by the H2-producing mutant, resulting in a 140-fold enhancement. This innovative method showcases the potential of coupling photocatalysis with methanotrophic biocatalysis for sustainable energy production. Additionally, the system introduces a new strategy for self-regeneration of sacrificial agents, offering a promising avenue for hydrogen production using greenhouse gases in an eco-friendly manner.

Origin of charges in bulk Si:HfO2 FeFET probed by nanosecond polarization measurements

FeFET technology offers the potential for fast, energy-efficient, low-cost, and high-capacity non-volatile memory and neuromorphic devices. However, charge trapping significantly affects device operation, leading to issues like read-after-write delay and limited endurance. Therefore, a detailed understanding of charge trapping, charge origin and its role in polarization switching is crucial. In this study, we uncover the spectral energy origin of polarization charges in Si:HfO2 N-FeFET by probing electron (conduction band) and hole (valence band) currents separately during polarization-voltage (P–V) measurements. We utilize a fast (∼20 ns) and modified positive-up-negative-down (PUND) technique, where bulk, source, and drain currents of the FeFET are measured separately. The nanosecond timescale of the measurement results in measurable currents in FeFETs having dimensions of a few μm. This charge separation shows that program (PRG, VGS > 0) charge originates from the conduction band, whereas erase (ERS, VGS < 0) originates from the valence band of the Si. Moreover, the polarization curve (P–V) of a cycled device (following 5000 PRG/ERS pulses) shows measurable hysteresis even though the transfer curve of the same device shows that the memory window in the threshold voltage vanishes. Therefore, the FeFET polarization state can be read without delay after write operation by the fast PUND measurement, both for pristine and cycled FeFETs.

Role of membrane H+ transport and plasmalemma excitability in pattern formation, long-distance transport and photosynthesis of Characean algae

Illuminated giant cells of Characeae comprise alternating areas with H+ pump activity and zones with high conductivity for H+/OH–, which create counter-directed H+ flows between the medium and the cytoplasm. In areas where H+ enters the cell, the pH on the surface (pHo) increases to pH 10, while the cytoplasmic pH (pHc) decreases. The lack of the permeant substrate of photosynthesis (CO2) and the acidic pHc shift in the region of external alkaline zones redirect electron transport in chloroplasts from CO2-dependent (assimilatory) pathway to O2 reduction. This electron transport route is associated with an increase in thylakoid membrane ΔpH and an enhanced nonphotochemical quenching (NPQ) of chlorophyll excitations, which underlies strict coordination between nonuniform distributions of pHo and photosynthetic activity in resting cells. When the action potential (AP) is generated, the longitudinal pH profile is temporarily smoothed out, while the heterogeneity of the distribution of NPQ and PSII photochemical activity (YII) sharply increases. The damping of the pHo profile is due to the suppression of the H+ pump and passive H+ conductance under the influence of an almost 100-fold increase in the cytoplasmic of Ca2+ level ([Ca2+]c) during AP. The increase in [Ca2+]c stimulates photoreduction of O2 in chloroplasts under external alkaline zones and, at the same time, arrests the cytoplasmic streaming, which causes the accumulation of excess amounts of H2O2 in the cytoplasm in areas of intense production of this metabolite, with a weak effect on areas of CO2 assimilation. These changes enhance the nonuniform distribution of cell photosynthesis and account for the long-term oscillations of chlorophyll fluorescence Fm' and the quantum efficiency of linear electron flow in microscopic cell areas after the AP generation.

Ultra-sensitive dengue NS1 protein detection via asymmetric source-drain, heterojunction and dual-dielectric cavities in a uniform tunnel FET biosensor

In this paper, we present a unique Asymmetric Source-Drain Heterojunction Dual-Dielectric Uniform Tunnel Field Effect Transistor (A-SD-HJ-DD-UTFET) based biosensor tailored for the early detection of dengue NS1 protein during the acute phase of infection offering early diagnosis and potentially life-saving intervention. The proposed biosensor design features simplified fabrication, a narrow drain region, and a dual material control gate, enhancing specificity and sensitivity for dengue virus detection. Using a heterojunction configuration, this device optimizes electron flow for improved detection accuracy. The roles of Tunnel Gate (TG) and Auxiliary Gate (AG) are studied in terms of band energy, electric field, electrostatic potential, and other sensitivity parameters. Sentaurus TCAD tool is utilized for analyzing the characteristics of the proposed A-SD-HJ-DD-UTFET biosensor. Simulation results indicate that the designed A-SD-HJ-DD-UTFET biosensor achieves a superior Subthreshold Swing (SS) of 15.4 mV/dec and an enhanced ION/IOFF sensitivity of about 2.25 × 10¹¹ with a maximum ON and minimum OFF state currents of 2.28 × 10–4 A/μm and 1.28 × 10–16 A/μm respectively for detecting NS1 protein of dengue. Additionally, it boasts a high switch ratio in the order of 1012. The proposed biosensor outperforms conventional devices, including the state-of-the-art Junctionless (JL)-TFET biosensors. The superior electrical characteristics of the proposed A-SD-HJ-DD-UTFET biosensor make it a promising device for early detection of the dengue NS1 protein, providing a potent solution for mitigating the spread of dengue infections.

Quercetin Alleviates Scleral Remodeling Through Inhibiting the PERK-EIF2α Axis in Experiment Myopia.

This study aims to investigate the effect of quercetin (QUE) on scleral remodeling by inhibiting the PERK-EIF2α signaling pathway and to evaluate its potential role in slowing myopia. Lens-induced myopia (LIM) guinea pigs were obtained and treated with QUE. After 4 and 6 weeks of treatments, ocular biological measurements were conducted. Hematoxylin and eosin (H&E) staining was used to observe the changes in scleral morphology and thickness, and Masson staining was used to examine scleral collagen fiber arrangement. Quantitative PCR (qPCR) and Western bolt were utilized to detect the mRNA and protein expression of PERK, EIF2α, MMP-2, TIMP-2, and collagen I in the scleral tissues. Calcium ion flow in each group was measured using noninvasive micro-test technology, and reactive oxygen species levels were detected by flow cytometry. Compared with the LIM group, the ocular measurements showed that the refractive errors and axial length of the eyes were significantly reduced in the LIM+QUE group (P < 0.01). H&E and Masson staining showed that sclera in the LIM+QUE group was thickened, collagen was dense, and the fiber gap was reduced. In the LIM+QUE group, the expression levels of PERK, EIF2α, and MMP-2 were decreased, whereas the expression levels of TIMP-2 and collagen I were increased. Calcium release and reactive oxygen species (ROS) in the LIM+QUE group were decreased. Quercetin ameliorates scleral remodeling in myopic guinea pigs by inhibiting the PERK-EIF2α signaling pathway, thereby alleviating the progression of myopia. These findings provide new experimental evidence for the potential application of quercetin in myopia prevention and treatment.

Assessing the Influence of Illumination on Ion Conductivity in Perovskite Solar Cells.

Whether illumination influences the ion conductivity in lead-halide perovskite solar cells containing iodide halides has been an ongoing debate. Experiments to elucidate the presence of a photoconductive effect require special devices or measurement techniques and neglect possible influences of the enhanced electronic charge concentrations. Here, we assess the electronic-ionic charge transport using drift-diffusion simulations and show that the well-known increase in capacitance at low frequencies under illumination is caused by electronic currents that are amplified due to the screening of the alternating electric field by the ions. We propose a novel characterization technique to detect a potential photoinduced increase in ionic conductivity based on capacitance measurements on fully integrated devices. The method is applied to a range of perovskite solar cells with different active layer materials. Remarkably, all measured samples show a clear signature of photoenhanced ion conductivity, posing fundamental questions on the underlying nature of the photosensitive mechanism.

Magnetite-mediating direct interspecies electron transfer is not pivotal role in directing electrons toward methane production from sulfate containing wastewater

Sulfate reduction can compete for electrons with methane production, thereby reducing methane production. Several factors, such as magnetite addition, carbon sources, and the chemical oxygen demand (COD)/SO42− ratio, can influence the direction of electron flow toward methanogenesis. However, their contributions to methane production remain unclear. In this study, the addition of magnetite significantly enhanced the maximum methane production rate (Rmax). The enrichment of Methanothrix and Methanobacterium in the conductive material groups indicated the establishment of a methanogenesis process through direct interspecies electron transfer (DIET). Although the DIET pathway enhanced Rmax in the conductive material groups, this increase did not translate into a higher methane yield in this study. The contribution of DIET pathway to methane yield was negligible compared with the effect of COD/SO42− ratio and carbon sources. The relative contribution of COD/SO42− ratio exceeded 40 % in directing electron flow.