Multiple Electron Research Articles

Space-temporal structure of the thunderstorm ground enhancements (TGEs)

We analyzed the structure of the Thunderstorm Ground Enhancement (TGE) using a particle detector network on Aragats. We performed a statistical analysis of the particle arrival time series on a nanosecond time scale using the largest TGE event on record, which occurred on May 23, 2023. Our findings confirm that the TGE is a mixture of multiple runaway electron avalanches that arrive independently and provide stable particle flux. The electron accelerator, operated by the dipole that emerges in the lower part of the thundercloud, sends copious electrons and gamma rays toward the Earth's surface that sustains for minutes. The experimental results are supported by simulations of electron multiplication and acceleration in strong atmospheric electric fields. We compare TGEs and Terrestrial Gamma Flashes (TGFs), which are brief bursts observed by gamma-ray detectors in orbit and are thought to be associated with atmospheric discharges.

Effect of 1‐Fluoro‐2‐iodobenzene Solvent Additive on the Crystallization of Donors and Acceptors, and Ultrafast Carrier Dynamics in Polymer Solar Cells

AbstractControlled sequential crystallization of donors and acceptors is a critical factor for achieving enhanced phase separation and efficient charge transfer performance in polymer solar cells (PSCs). In this study, a comprehensive investigation of a structurally simple solvent additive, 1‐fluoro‐2‐iodobenzene (OFIB) is conducted, which efficiently controls the morphology of the active layer, resulting in fibrous assembly and significantly enhancing the power conversion efficiency from 16.34% to 18.38% based on the PM6:L8‐BO system. Density functional theory, molecular dynamics simulations, and grazing incidence small‐ and wide‐angle X‐ray scattering techniques reveal that the addition of OFIB to the processed blend aligns the orientation of the acceptor molecules, thereby enhancing the overall π–π stacking in the active layer. OFIB establishes nearly equal‐strength π–π interactions with the conjugated frameworks of both the donor and acceptor materials, benefiting from the multiple electron conjugation between its iodine atom and the conjugated framework in the active layer. Femtosecond‐timescale photophysical studies demonstrate that the OFIB‐optimized active layer shows reduced exciton losses at the donor–acceptor interface. This study offers a new perspective on the mechanism underlying the function of solvent additives and presents a comprehensive research methodology that will guide the development of next‐generation non‐fullerene acceptors for efficient PSCs.

An Organic Molecular Cathode Composed of Naphthoquinones Bridged by Organodisulfide for Rechargeable Lithium Battery.

Organic electrodes that embrace multiple electron transfer and efficient redox reactions are desirable for green energy storage batteries. Here, a novel organic electrode material is synthesized, i.e., 2, 2'-((disulfanediylbis (4, 1-phenylene)) bis(azanediyl)) bis (naphthalene-1, 4-dione) (MNQ), through a simple click reaction between common carbonyl and organosulfur compounds and demonstrate its application potential as a high-performance cathode material in rechargeable lithium batteries. MNQ exhibits the aggregation effect of redox-active functional groups, the advantage of fast reaction kinetics from molecular structure evolution, and the decreased solubility in aprotic electrolytes resulting from intermolecular interactions. As expected, the MNQ electrode exhibits a high initial discharge capacity of 281.2mAhg-1 at 0.5 C, equivalent to 97.9% of its theoretical capacity, and sustains stable long-term cycling performance of over 1000 cycles at 1 C. This work adds a new member to the family of organic electrode materials, providing performance-efficient organic molecules for the design of rechargeable battery systems, which will undoubtedly spark great interest in their applications.

Coherences of Photoinduced Electron Spin Qubit Pair States in Photosystem I.

This publication presents the first comprehensive experimental study of electron spin coherences in photosynthetic reaction center proteins, specifically focusing on photosystem I (PSI). The ultrafast electron transfer in PSI generates spin-correlated radical pairs (SCRPs), which are entangled spin pairs formed in well-defined spin states (Bell states). Since their discovery in our group in the 1980s, SCRPs have been extensively used to enhance our understanding of structure-function relationships in photosynthetic proteins. More recently, SCRPs have been utilized as tools for quantum sensing. Electron spin decoherence poses a significant challenge in realizing practical applications of electron spin qubits, particularly the creation of quantum entanglement between multiple electron spins. This work is focused on the systematic characterization of decoherence in SCRPs of PSI. These decoherence times were measured as electron spin echo decay times, termed phase memory times (TM), at various temperatures. Decoherence was recorded on both transient SCRP states P700+A1- and thermalized states. Our study reveals that TM exhibits minimal dependence on the biological species, biochemical treatment, and paramagnetic species. The analysis indicates that nuclear spin diffusion and instantaneous diffusion mechanisms alone cannot explain the observed decoherence. As a plausible explanation we discuss the assumption that the low-temperature dynamics of methyl groups in the protein surrounding the unpaired electron spin centers is the main factor governing the loss of the spin coherence in PSI.

Abstract 17715: Heart Rate Reduction Alone Produces Reverse Remodeling in Heart Failure Patients Refractory to Beta-Blockers: The PROBE-IT Trial

In a 2-center trial ( P ulse R eduction o n Be ta-Blocker and I vabradine T herapy (PROBE-IT)) we tested the hypothesis that failure to adequately reduce heart rate (HR) contributes to non-response to beta-blockers. Twenty-two dilated cardiomyopathy patients (DCM) with a sinus rhythm (SR) heart rate (HR) ≥70 bpm without reverse remodeling after target doses of beta-blockers were randomized 2:1 to 5±2.5 mg b.i.d of ivabradine (IVB) or matching placebo, and treated for 24 weeks with continuation of beta-blockers. Echocardiograms for LVEF measurements and endomyocardial biopsies for measurement of global gene expression by RNA-Sequencing were performed at baseline and end of study. The protocol design aimed for approximately equal numbers of patients with a HR reduction (HRι) and a control group with no change in HR (HRν), with the predefined statistical analysis plan comparing subjects above and below the median HR change. Characteristics and changes from baseline in the 17 patients who completed the trial were (*P <0.05, † P <0.01 vs. HRν):HRν patients had a longer duration of HF,, 112 months vs. 35 months in HRι (P = 0.005). In HRι vs. HRν, gene expression findings included 18 mRNAs at a P <0.0005 and 39 at a P of <0.001 with higher abundance, and 34 (P <0.0005) and 94 (P <0.001) lower abundance. The classification of these genes was distinct from molecular changes described for reverse remodeling from beta-blockers alone, with only a 2.1% overlap. Gene expression changes that could have contributed to reverse remodeling in HRι included: increases in NRG1 (neuregulin 1), PP1R3C (protein phosphatase 1), and multiple mitochondrial electron transport genes; and lower expression of genes encoding cardiotrophin-1 cytokines (CTF1 and CLCF1). Conclusions: In NDC patients meeting the PROBE-IT entry criteria, HR lowering produces a substantial increase in LVEF accompanied by gene expression changes that differ from those associated with beta-blocker therapy.

Empirical Analysis of Electron Beam Lithography Optimization Models from a Pragmatic Perspective

Electron Beam (EB) lithography is a process of focussing electron beams on silicon wafers to design different integrated circuits (ICs). It uses an electron gun, a blanking electrode, multiple electron lenses, a deflection electrode, and control circuits for each of these components. But the lithography process causes critical dimension overshoots, which reduces quality of the underlying ICs. This is caused due to increase in beam currents, frequent electron flashes, and reducing re-exposure of chip areas. Thus, to overcome these issues, researchers have proposed a wide variety of optimization models, each of which vary in terms of their qualitative & quantitative performance. These models also vary in terms of their internal operating characteristics, which causes ambiguity in identification of optimum models for application-specific use cases. To reduce this ambiguity, a discussion about application-specific nuances, functional advantages, deployment-specific limitations, and contextual future research scopes is discussed in this text. Based on this discussion, it was observed that bioinspired models outperform linear modelling techniques, which makes them highly useful for real-time deployments. These models aim at stochastically evaluation of optimum electron beam configurations, which improves wafer’s quality & speed of imprinting when compared with other models. To further facilitate selection of these models, this text compares them in terms of their accuracy, throughput, critical dimensions, deployment cost & computational complexity metrics. Based on this discussion, researchers will be able to identify optimum models for their performance-specific use cases. This text also proposes evaluation of a novel EB Lithography Optimization Metric (EBLOM), which combines multiple performance parameters for estimation of true model performance under real-time scenarios. Based on this metric, researchers will be able to identify models that can perform optimally with higher performance under performance-specific constraints.

In situ growing CNTs/TiO2 heterojunction on MXene sheets for enhanced microwave absorption via multiple electron transfer paths and polarization

The novel two-dimensional Ti3C2Tx material exhibits great potential for microwave absorption owing to its 2D layered graphene-like structure and unique physical properties. However, the limited release of absorbing properties due to the low dielectric loss of Ti3C2Tx and its single loss mechanism pose challenges in meeting the functional requirements for microwave absorbers. Herein, carbon nanotubes (CNTs) were grown on the Ti3C2Tx substrates in a tip growth mode under the catalytic influence of Ni using the in situ induced method. Consequently, Ti3C2Tx/CNTs/TiO2 (TCT) structures were successfully prepared through carbonization conditions. It is worth noting that the composite material TCT-800 exhibits excellent absorption performance. The minimum reflection loss (RLmin) value reaches −44.6 dB when the matching thickness is only 1.4 mm, and the corresponding effective absorption bandwidth (EAB, RL < −10 dB) spans from 11.9 GHz to 15.9 GHz, totaling a range of 4.2 GHz. The excellent electromagnetic wave absorption performance of TCT-800 composites is attributed to the polarization phenomenon of more heterogeneous interfaces constructed by Ti3C2Tx nanosheets, CNTs, and TiO2 nanoparticles. This work provides a strategy for synthesizing Ti3C2Tx-based composites with strong electromagnetic attenuation and wide absorption bandwidth performance.

Potential investigation of combined natural dye pigments extracted from ivy gourd leaves, black glutinous rice and turmeric for dye-sensitised solar cell

Environmental sustainability, resource availability, and cost-effectiveness are the driving forces behind the search for natural sensitised dyes to replace synthetic ones. Using a combination of pigments as the sensitised dye in dye-sensitised solar cells (DSSCs) offers several advantages over using a single pigment. In this present study, natural dyes with different pigments were extracted from three local plants: Coccinia grandis (Ivy gourd leaves, IGL), Oryza sativa Linn (Black glutinous rice, BGR), and Curcuma longa L. (Turmeric, TM). Each colour extract absorbed various wavelengths of light. It was found that the single IGL-dye (green) had a greater light absorption and energy band gap over visible light than other extracts (dyes). Then combinations of these dyes were examined. A sensitised dye combination with a primary to secondary dye in a volumetric ratio of 80/20 exhibited multiple energy band gaps, implying multiple electron excitations at different photon energy levels. Compared to other mixed dyes, IGL/TM-dye had the highest absorbance and electron excitation at three wavelengths with the smallest energy band gap values of 1.74, 2.51, and 2.59 eV. The IGL-dye had the highest DSSC efficiency of 0.15 % for single dyes, followed by the TM-dye and BGR-dye, which had 0.12 % and 0.04 %, respectively. Interestingly, for combined dyes, the IGL/TM dye increased DSSC efficiency to 0.3 %. Since natural dyes tend to be less effective in DSSCs than synthetic dyes because they have a narrower absorption range, higher redox potentials, shorter operational lifetimes, higher rates of electron recombination, and different molecular structures, the dye co-sensitization strategy is one of the best ways to make more effective cells in the future.

CECILIA: The Faint Emission Line Spectrum of z ∼ 2–3 Star-forming Galaxies

We present the first results from Chemical Evolution Constrained Using Ionized Lines in Interstellar Aurorae (CECILIA), a Cycle 1 JWST NIRSpec/MSA program that uses ultra-deep ∼30 hr G235M/F170LP observations to target multiple electron temperature-sensitive auroral lines in the spectra of 33 galaxies at z ∼ 1–3. Using a subset of 23 galaxies, we construct two ∼600 object-hour composite spectra, both with and without the stellar continuum, and use these to investigate the characteristic rest-optical (λ rest ≈ 5700–8500 Å) spectrum of star-forming galaxies at the peak epoch of cosmic star formation. Emission lines of eight different elements (H, He, N, O, Si, S, Ar, and Ni) are detected, with most of these features observed to be ≲3% the strength of Hα. We report the characteristic strength of three auroral features ([N ii]λ5756, [S iii]λ6313, and [O ii]λ λ7322, 7332), as well as other semi-strong and faint emission lines, including forbidden [Ni ii]λ λ7380, 7414 and permitted O i λ8449, some of which have never before been observed outside of the local Universe. Using these measurements, we find T e [N ii] = 13,630 ± 2540 K, representing the first measurement of electron temperature using [N ii] in the high-redshift Universe. We also see evidence for broad line emission with a FWHM of km s−1; the broad component of Hα is 6.01%–28.31% the strength of the narrow component and likely arises from star-formation-driven outflows. Finally, we briefly comment on the feasibility of obtaining large samples of faint emission lines using JWST in the future.

The effect of different AlGaN insertion layer thicknesses on the photoelectric properties of InGaN/AlGaN near UV light emitting diodes

In this paper, a near-ultraviolet LED structure was fabricated on a sapphire substrate by using metal–organic chemical vapor deposition with an undoped AlGaN insertion layer introduced between multiple quantum wells and electron blocking layers, and the effect of layer thickness on light-electric performance was investigated. Results of epitaxial structure characterization show that the introduction of an undoped AlGaN insertion layer almost does not affect the crystal quality and surface morphology of the LED epitaxial structure. Electroluminescence testing results indicate that as the insertion layer thickness increases, the device performance initially increases and then decreases. Furthermore, simulation analysis suggests that increasing the insertion layer thickness reduces the injection efficiency of carriers, lowers the radiative recombination rate and light emission performance of the active region's carriers. Additionally, the AlGaN insertion layer can effectively suppress the diffusion of Mg impurities, reduce the non-radiative recombination rate in the multiple quantum well active region, and thus improve the LED's light emission performance. Overall, under the competing effects of these two mechanisms, the optimal light emission performance for the near-ultraviolet LED is achieved when the insertion layer thickness is 1 nm.

Breaking the Activity and Stability Bottlenecks of Electrocatalysts for Oxygen Evolution Reactions in Acids.

Oxygen evolution reaction (OER) is a cornerstone reaction for a variety of electrochemical energy conversion and storage systems such as water splitting, CO2 /N2 reduction, reversible fuel cells, and metal-air batteries. However, OER catalysis in acids suffers from extra sluggish kinetics due to the additional step of water dissociation along with its multiple electron transfer processes. Furthermore, OER catalysts often suffer from poor stability in harsh acidic electrolytes due to the severe dissolution/corrosion processes. The development of active and stable OER catalysts in acids is highly demanded. Here, we review the recent advances in OER electrocatalysis in acids and summarise the key strategies to overcome the bottlenecks of activity and stability for both noble-metal-based and noble metal-free catalysts, including i) morphology engineering, ii) composition engineering, and iii) defect engineering. Recent achievements in operando characterization and theoretical calculations are summarised which provide an unprecedented understanding of the OER mechanisms regarding active site identification, surface reconstruction, and degradation/dissolution pathways. Finally, we offer our views on the current challenges and opportunities to break the activity-stability relationships for acidic OER in mechanism understanding, catalyst design, as well as standardised stability and activity evaluation for industrial applications such as proton exchange membrane water electrolysers and beyond. This article is protected by copyright. All rights reserved.

EVOLUTION OF DEFECTS DURING COLD ROLLING OF LOW-ALLOY MOLYBDENUM ALLOYS

The experimental work briefly describes the technology of multiple electron beam melting, which allows to obtain low-alloy molybdenum alloys with other carbide-forming elements and carbon. Two new alloys described in the work allow deformation by cold rolling up to a thickness of 0.17 mm. Based on the modified Golovin—Sims expression, it is shown that an alloy with dispersed carbides (size 30-200 nm) is strengthened during cold rolling much stronger than an alloy in which only large (≥1 microns) carbides are present. The evolution of continuity defects during cold rolling with an increase in the degree of deformation is traced.

Lossless Monochromator in an Ultrafast Electron Microscope Using Near-Field THz Radiation.

The ability to form monoenergetic electron beams is vital for high-resolution electron spectroscopy and imaging. Such capabilities are commonly achieved using an electron monochromator, which energy filters a dispersed electron beam, thus reducing the electron flux to yield down to meV energy resolution. This reduction in flux hinders the use of monochromators in many applications, such as ultrafast transmission electron microscopes (UTEMs). Here, we develop and demonstrate a mechanism for electron energy monochromation that does not reduce the flux-a lossless monochromator. The mechanism is based on the interaction of free-electron pulses with single-cycle THz near fields, created by nonlinear conversion of an optical laser pulse near the electron beam path inside a UTEM. Our experiment reduces the electron energy spread by a factor of up to 2.9 without compromising the beam flux. Moreover, as the electron-THz interaction takes place over an extended region of many tens of microns in free space, the realized technique is highly robust-granting uniform monochromation over a wide area, larger than the electron beam diameter. We further demonstrate the wide tunability of our method by monochromating the electron beam at multiple primary electron energies from 60 to 200keV, studying the effect of various electron and THz parameters on its performance. Our findings have direct applications in the fast-growing field of ultrafast electron microscopy, allowing time- and energy-resolved studies of exciton physics, phononic vibrational resonances, charge transport effects, and optical excitations in the mid IR to the far IR.

The Brain Endothelial Cell Glycocalyx Plays a Crucial Role in the Development of Enlarged Perivascular Spaces in Obesity, Metabolic Syndrome, and Type 2 Diabetes Mellitus.

The brain endothelial cell (BEC) glycocalyx (ecGCx) is a BEC surface coating consisting of a complex interwoven polysaccharide (sweet husk) mesh-like network of membrane-bound proteoglycans, glycoproteins, and glycosaminoglycans (GAGs) covering the apical luminal layer of the brain endothelial cells. The ecGCx may be considered as the first barrier of a tripartite blood-brain barrier (BBB) consisting of (1) ecGCx; (2) BECs; and (3) an extravascular compartment of pericytes, the extracellular matrix, and perivascular astrocytes. Perturbations of this barrier allow for increased permeability in the postcapillary venule that will be permissive to both fluids, solutes, and proinflammatory peripherally derived leukocytes into the perivascular spaces (PVS) which result in enlargement as well as increased neuroinflammation. The ecGCx is known to have multiple functions, which include its physical and charge barrier, mechanical transduction, regulation of vascular permeability, modulation of inflammatory response, and anticoagulation functions. This review discusses each of the listed functions in detail and utilizes multiple transmission electron micrographs and illustrations to allow for a better understanding of the ecGCx structural and functional roles as it relates to enlarged perivascular spaces (EPVS). This is the fifth review of a quintet series that discuss the importance of EPVS from the perspective of the cells of brain barriers. Attenuation and/or loss of the ecGCx results in brain barrier disruption with increased permeability to proinflammatory leukocytes, fluids, and solutes, which accumulate in the postcapillary venule perivascular spaces. This accumulation results in obstruction and results in EPVS with impaired waste removal of the recently recognized glymphatic system. Importantly, EPVS are increasingly being regarded as a marker of cerebrovascular and neurodegenerative pathology.

Nano to macro-scale elastic and plastic characteristics of calcium metal and implications for rechargeable battery applications

Multivalent metals (Ca, Mg, Al, etc.) are promising for anodes of rechargeable batteries owing to their high theoretical capacity that stems from multiple electron transfer per redox center. Among these multivalent metals, calcium exhibits a low electrochemical potential of −2.87 V (relative to the standard hydrogen electrode) and is the fifth most abundant element in the earth’s crust. In addition to resolving electrochemical issues, prior to practical use it remains critical to fully understand calcium’s mechanical properties to mitigate any potential degradation and failure mechanisms. To this end, we have conducted mechanical testing of Ca at the nano- and macro-scale through nanoindentation and bulk compression testing. Nanoindentation tests indicate an elastic modulus that ranges from 25.2 to 21.7 GPa and a hardness that ranges from 0.88 to 0.46 GPa as the indentation depth increases from 0.25 to 10 μm. Bulk compression tests show a yield strength of 107 ± 4.6 MPa (average ± standard deviation). These tests demonstrate a minimal sensitivity of calcium’s mechanical properties to strain rate or “size effects”, which differs from previous studies of alkali metal anodes, likely stemming from Ca’s relatively high melting point compared to the alkali metals. We conclude the manuscript by discussing the implications of these measured mechanical properties in the context of energy storage applications.

A new electro-active bacterium, Paraclostridium sp. AKS46, converts waste efficiently into electricity in microbial fuel cell

Microbial fuel cell (MFC) has gained importance for its ability to convert waste into energy. Exoelectrogens are the essential component of MFC that plays an important role in determining the efficiency of MFC. Therefore, the current study aimed at isolating efficient exoelectrogen(s) with significant biodegradation ability. Based on iron reduction ability, the current study isolated a bacterium that exhibited a high level of current generation and significant COD reduction (58–70%) of the medium/waste used in MFC. The maximum current density achieved in the 80 ml capacity of two electrodes MFC by the new isolate was 632 mA/m2. The ribotyping analysis identified this isolate as a member of the Paraclostridium genera and named Paraclostridium sp. AKS46. Further study revealed that this new isolate is capable of forming a biofilm on the anode, and the result showed a positive correlation of this biofilm formation with the current generation. Field emission-scanning electron microscopy (SEM), energy dispersive X-ray-SEM, Fourier transform infrared spectroscopy, gas chromatography-mass spectroscopy, and high-performance liquid chromatography analysis of the AKS46 reveal multiple electron transfer routes to the electrode surface. Furthermore, this new isolate was found to be capable of utilizing diverse carbon sources and thus generated current efficiently using different household wastes in MFC. Hence, the present study isolated an efficient exoelectrogen, Paraclostridium sp. AKS46, which can generate a high level of electricity with a significant reduction of COD of diverse wastes. Thus the new isolate has the potential to be used in MFC for sustainable development.

Potential for electron acoustic mode in the coma of a weakly outgassing comet

This study aims to explore the electron acoustic (EA) mode in the vicinity of comet 67P/Churyumov–Gerasimenko, considering the existence of multiple electron species. In Region I, where all three suprathermal, warm and cold electron populations present and in Region II, where only warm and cold electrons present there is a chance to observe the EA mode for the plasma parameters measured at the comet. At smaller wave number (k), hotter electrons whereas at larger k, the cold electrons cause damping of the mode, and the mode only propagates at intermediate wave lengths. In these regions, it is determined that the mode observation enhances with the streaming speeds of hotter species, and it could be observed even for , which is not possible at lower or in the absence of drift speeds. In Region III, both warm and suprathermal electrons significantly damp the mode and hence, it is non-observable for the reported plasma parameters, and the mode could be only observable for the temperature ratio and surprisingly, the most favorable density for the observation is . Here, and stand for suprathermal and warm electron temperatures, respectively.

(Invited) Recent Development of Electrochemical Nitrate Reduction

Understanding the complexities of nitrogen cycle is critical because when the cycle is not in balance, excess reduced and oxidized nitrogen compounds could result in harmful impacts to life. Electrocatalytic conversion of waste nitrate (NO3 -) to benign dinitrogen (N2) and ammonia (NH3) fuel is an appealing strategy that may easily integrate with renewable energy. The process does not require chemical addition and thus requires operating costs lower than thermal routes. Nearly all nitrogen-based fertilizers rely on ammonia as a feedstock, and thus the demand for this chemical is heavily dependent on the global population and food demand. Over the next three decades, the global population will continue to dictate the market size and value for ammonia, which consequently will have a significant impact on our energy infrastructure. While electrochemical nitrogen reduction reaction (NRR) requires multiple proton and electron transfer process, ammonia production from nitrate reduction (NO3RR) is catalytic easier than NRR because the adsorbed/activated ion reactants (nitrate and nitrite) have an advantage of a lower dissociation energy for the N−O and N=O bonds (204 and 607 kJ mol-1) than that of N≡N bond (941 kJ mol-1). The synergistic effect between Cu and Pd has shown a high nitrate conversion yield and nitrogen selectivity. Engineering the Pd and Cu sites is critical but examination of the use of secondary metals in shape-controlled nanoparticle and atomic reconstruction are rare.Here, we controlled Cu surface coverage on Pd nanocube nanoparticle to steer the selectivity between nitrogen and ammonia. In addition, the engineered the atomic structure of Pd and Cu nanoparticles showed high nitrate conversion yield, excellent dinitrogen selectivity, and outstanding cyclic stability. This study provides insights into the rational design of NO3RR electrocatalyst for efficiently transforming nitrate into nitrogen and ammonia.

(Digital Presentation) Understanding the Electrochemical Stability of Potential Current Collectors in Zinc Sulfate Electrolyte for Rechargeable Aqueous Zinc Ion Battery Application

The need for clean and sustainable energy sources has witnessed a sudden upsurge in recent years owing to rising environmental degradation and climate disruption brought on by an overdependence on fossil fuels [1-3]. Electrochemical energy conversion technology is a crucial complement to the storage and on-demand utilization of renewable energy resources [4-6]. Rechargeable aqueous zinc ion batteries (AZIBs) have gained a significant research upsurge in recent times owing to their attractive potential for large-scale energy storage applications. In addition to low cost and naturally abundant raw materials, AZIBs technology offers competitive electrochemical performance and compatibility with water-based electrolyte systems, thereby eliminating the safety concerns associated with prevalent lithium-based battery technology. Moreover, multivalent AZIBs offer the opportunity to attain high energy and power density by permitting multiple electron transfers during reversible electrochemical operations [7]. In the context of AZIBs, significant research efforts are being actively pursued to develop high energy density cathode materials and to address the issue of Zn dendrite formation [8]. However, the selection of stable and low-cost current collectors is equally important as it serves as a bridge between the battery components and the external circuit, thereby influencing the battery capacity and its rate capability [9-10]. In this work, we have analyzed the electrochemical behavior of potential current collectors that are used globally in battery applications, namely Ni, Al, carbon paper, Cu mesh, graphite, and stainless steel in near-neutral aqueous ZnSO4 electrolyte (pH value = 5-6). The electrochemical stability of different current collectors has been investigated using linear sweep voltammetry and chronoamperometry techniques for their application as anode and cathode collectors. Scanning electron microscopy analysis has also been performed to understand the sign of corrosion post-electrochemical study. With stability up to 2.3 V w.r.t. Zn/Zn2+, Ni has proved to be the most corrosion-resistant current collector among the tested collectors on the cathode side. Although Zn itself is sufficiently stable at the anode side than any other current collector under the ZnSO4 electrolyte environment, Ni has shown considerable stability. Nonetheless, understanding the electrochemical stability of current collectors for AZIBs is a vital step in their design and future practical applications.

Multiple electron spin resonance echoes observed for paramagnetic defects in diamond at room temperature

Magnetic resonance offers an invaluable testbed for observing and studying the fundamental concepts of quantum cavity interactions with two-level systems in the microwave regime. Typically, these experiments are conducted at low cryogenic temperatures, utilizing spin systems embedded within a high-quality (Q-factor) superconducting cavity. Recent studies indicate that under these conditions, especially in a high-cooperativity regime with strong collective coupling between an electron spin system and a microwave cavity, multiple spin echoes can be detected. These echoes are interpreted as manifestations of coherent quantum effects. To put it simply, photons within the cavity can excite the spin system, which subsequently can stimulate the cavity, creating a feedback loop. In our research, we demonstrate that a specially designed moderate-Q cavity, paired with diamond crystals rich in nitrogen vacancy (NV) centers, allows us to observe such nonlinear quantum phenomena, even at ambient temperatures. Crucially, our experimental design necessitates amplifying the net number of spins for a specific, limited spin concentration. This is achieved by lowering the spins' thermodynamic temperature (as opposed to their physical temperature) to a few kelvins. Notably, we find that maintaining high cooperativity or strong coupling is not essential for these observations. The potential to observe significant microwave cavity quantum effects at room temperature could be useful for future applications, such as quantum memories and quantum sensing.