The internal alternative NADH dehydrogenase (Ndi1) is the electron input in the Saccharomyces cerevisiae respirasome.

Elemental sulfur enhances autotrophic denitrifying phosphorus removal from carbon-deficient wastewater through microbial synergy and electron transfer optimization.

Transitional role of granular activated carbon for potentially promoting the expression of conductive pili and quorum sensing during anaerobic digestion.

Carbon quantum dot-induced bio-hybrid of Shewanella oneidensis MR-1 for enhanced extracellular hexavalent chromium reduction.

The FY-4B satellite, launched in June 2021 as China’s new-generation geostationary meteorological satellite, carries three identical High-Energy Particle Detectors (HEPDs) that enable multi-directional, wide-spectral measurements of energetic electrons. The three units are mounted in the zenith (−Z), flight (+X with a +Y offset of 30°), and anti-flight (−X with a −Y offset of 30°) directions, allowing simultaneous observations from nine look directions over a field of view close to 180° in the 0.4–4 MeV energy range (eight energy channels). This paper systematically presents the design principles of the HEPD electron detector, the ground calibration scheme, and preliminary in-orbit validation results. The probe employs a multi-layer silicon semiconductor telescope technique to achieve high-precision measurements of electron energy spectra, fluxes, and directional anisotropy in the 0.4–4 MeV range. Ground synchrotron calibration shows that the energy resolution is better than 16% for energies above 1 MeV, and the angular resolution is about 20°, providing a solid basis for subsequent quantitative inversion. During in-orbit operation, HEPD remains stable under both quiet conditions and strong geomagnetic storms: the measured electron fluxes, differential energy spectra, and directional distributions show good agreement with GOES-16 observations in the same energy bands during quiet periods and for the first time provide from geostationary orbit pitch-angle-resolved images of the minute-scale evolution of electron enhancement events. These results demonstrate that HEPD is capable of long-term monitoring of the geostationary radiation environment and can supply high-quality, continuous, and reliable data to support studies of radiation-belt particle dynamics, data assimilation in space weather models, and radiation warnings for satellites in orbit.

Abstract Earth's outer radiation belt electron flux is highly variable and can be enhanced by over an order of magnitude over timescales less than one day, as observed during the October 2012 storm. Previous studies of this storm (e.g., Reeves et al., 2013, https://doi.org/10.1126/science.1237743 ) have invoked local acceleration to explain this. However, here, we argue that the observations can instead be explained by fast inward radial transport. One method often invoked to distinguish between these two acceleration processes is the existence of local peaks in electron phase space density (PSD) as a function of L * at fixed first, M, and second, K, adiabatic invariants. However, this method relies on the assumption that the evolution of the PSD as a function of L * occurs over timescales slower than the satellite orbital period. Here, high spatiotemporal resolution data from the Global Positioning System (GPS) spacecraft constellation is used to show that enhancements in the PSD occur during the October 2012 storm over short timescales not resolvable by the Van Allen Probes. In addition, Geostationary Operational Environmental Satellite spacecraft data also indicate that these enhancements are consistent with relativistic electron injections. A radial diffusion model is shown to reproduce the PSD dynamics observed by the Van Allen Probes, once rapid variations at the simulation outer boundary are included, consistent with GPS data. This verifies that apparently “locally growing” peaks in PSD along high apogee satellite orbits can be produced by fast inward radial transport without requiring the action of any local acceleration processes.

Ceramic samples of monocomponent (CaO, MgO, ZnO and WO3) and two-component (ZnWO4, MgWO4, CaWO4) compositions were synthesized by direct impact of high-energy electron flow on the charge of stoi chiometric composition. Radiation synthesis of samples weighing about 50 g is realized in time of 10s with out the use of any additional substances to stimulate the process. Systematic studies of the dependence of ra diation synthesis of tungstate ceramics on the flux power density have been performed for the first time. It was found that the dependences of synthesis efficiency on the flux power density of monocomponent (CaO, MgO, ZnO and WO3) and two-component (ZnWO4, MgWO4, CaWO4) ceramic samples have the form of constantly increasing curves. There is a threshold above which the synthesis is realized for all synthesized samples. The effect of mutual influence of charge components on the efficiency of synthesis of two component systems was found. Synthesis of ZnWO4, MgWO4, CaWO4 ceramics is realized under the same conditions of radiation treatment, while the thresholds of synthesis realization of one-component samples of CaO, MgO and ZnO and WO3 ceramics differ significantly. It is shown that at all used modes of radiation treatment the formation of ceramics with the same properties are realized. This effect is due to the inhomoge neous distribution of electron flux energy losses in the substance. Synthesis of two-component (ZnWO4, MgWO4, CaWO4) ceramic samples is realized at the same power density above 1,0 kW/cm2. The radiation synthesis of the ZnWO4, MgWO4, CaWO4 ceramics is mainly determined by tungsten oxide.

Recent advances in nanotechnology have created the need to manufacture 3D nanostructures with controlled material composition. Focused Electron Beam Induced Deposition (FEBID) is a nanoprinting technique offering highest spatial resolution combined with the ability to directly 3D-print almost any shape. It relies on local electron-induced dissociation of metal-ligand organometallic molecules adsorbed onto a substrate. So far FEBID continuum modeling involves the surface kinetics of precursor molecules during electron irradiation and succeeds in the prediction of nanoprint shape and growth rate and forms nowadays the basis of software for 3D nano-printing of nanostructures. Here, the model is expanded to the surface kinetics of detached ligands. Involving their dissociation and desorption behavior allows to predict trends in the metallic composition of the nanoprinted material and to define desirable nanoprint process windows as function of electron exposure time and flux. The theoretical foundations of the model is presented, validate it experimentally for chromium and silver precursors, compare calculated values with literature data for various precursors, and discuss its potential to design new experiments. This contribution enhances the understanding of FEBID dynamics and provides a versatile framework for predictive FEBID material nano-printing.

The methanolysis of urea represents a promising green route for the synthesis of dimethyl carbonate (DMC), a versatile compound with applications in sustainable chemistry and energy storage. In this work, a comprehensive quantum chemical investigation of the reaction mechanism is presented using density functional theory (DFT), focusing on both uncatalyzed and organotin-catalyzed systems, considering both stepwise and concerted pathways. For MC production, both the stepwise and the concerted mechanisms mediated by a methanol dimer exhibit the lowest activation enthalpies. Consequently, an effective activation enthalpy of 24.0 kcal/mol was determined, in excellent agreement with the experimental value of 23.45 kcal/mol. In contrast, the bimolecular stepwise and concerted models exhibited higher barriers (ΔH‡ ≈ 42-52 kcal/mol). Entropy values indicated that mechanisms with two methanol molecules involve higher preorganization (ΔS‡ ≈ -60 cal/mol K), compared to -30 cal/mol K in single-molecule pathways. For DMC production from the methyl carbamate intermediate, the rate-limiting step, it was analyzed with and without an organotin catalyst. Catalysis lowers the activation enthalpy by approximately 10 kcal/mol, yielding a value of 24.9 kcal/mol for the methanol monomer catalyzed system, in good agreement with the experimental ΔH‡ of 24.3 kcal/mol. To deepen mechanistic understanding, we employed advanced quantum descriptors including reaction force analysis, reaction electronic flux (REF), and natural bond orbital (NBO) charge evolution. These tools revealed synchronous bond rearrangements and electronic polarization effects that govern transition state stability, mainly by the electronic charges of the carbon atom in the carbonyl group and the amine group in the sense Cδ+-Nδ-. This study provides novel mechanistic insights into the dual role of hydrogen bonding and Lewis acid catalysis in DMC synthesis and demonstrates the utility of quantum chemical tools in elucidating complex reaction pathways, offering a foundation for rational catalyst design.

Abstract The electron rolling pin distribution, showing electron pitch angles primarily at 0°, 90°, and 180°, has been recently observed behind dipolarization fronts (DFs) in the magnetosphere of Earth. However, the relation between such distribution and the leading edge of tailward magnetic reconnection jets, also known as anti‐dipolarization fronts (ADFs), is still unclear. Here, by utilizing high‐resolution data of the Magnetospheric Multiscale (MMS) mission, we provide the first observation of electron rolling pin distribution behind ADF. Such distribution of Maxwellian electrons appears in 1.3–5 keV and is modulated by firehose fluctuations: electron fluxes are high at wave troughs (|B|‐minima) and are low at wave crests. The results of Liouville mapping and the electron loss cone angles are consistent with the spacecraft observations respectively, indicating such distribution is formed by the combination of global‐scale Fermi acceleration and local‐scale electron trapping. These findings highlight the importance of ADFs in magnetospheric convection.

Abstract Low‐altitude measurements of energetic electron fluxes offer insight into the dynamics of the radiation belts and plasma sheet. However, distinguishing between key magnetospheric regions–such as inner belt, slot region, outer belt, and plasma sheet–based on low‐altitude data remains challenging, particularly for missions lacking pitch‐angle resolution. A commonly used boundary indicator, the flux anisotropy (i.e., precipitating‐to‐trapped flux ratio), is unavailable in such cases. In this study, we propose an alternative approach to identify the plasma sheet—radiation belt interface, commonly associated with the isotropy boundary, using high energy‐resolution measurements from the Colorado Inner Radiation Belt Experiment (CIRBE) CubeSat. We demonstrate that this boundary is marked by a distinct spectral change: a power‐law form in the plasma sheet transitions to an exponential form within the outer radiation belt. These findings are supported by comparisons with Polar‐orbiting Operational Environmental Satellites (POES) observations, and we discuss the potential mechanisms responsible for the spectral transition.

Mechanistic insights into the enhancement of azithromycin biodegradation by extracellular polymeric substances: Roles of metabolic activity, electron transfer, and reactive oxygen species.

Abstract Microinjections are periodic enhancements of 10 s–100 s keV electron fluxes at a cadence of several minutes on the dawnside or duskside magnetosphere. Here, we extend previous studies by comprehensively examining the plasma and wave observations provided by the Magnetospheric Multiscale (MMS) mission. We report an event study showing that microinjection oscillates in specific phase relations relative to lower‐energy (1 keV) plasmas (180° out of phase) and the electromagnetic waves and the corresponding E × B velocity (90° out of phase). The phase relations can be explained by the following simple scenario: A plasma boundary, which separates the low‐energy plasmas and the plasma accessing the 10 s–100 s keV electrons, oscillates over the quasi‐stationary MMS satellites due to the Ultra‐Low Frequency (ULF) waves. The phase relations and the simple explanation suggest that the period of microinjection may be apparent, that is, the 10 s–100 s keV electron flux could be stable in the rest frame of its local plasma.

Accelerating iron redox cycling via acetate modification: a ligand engineering for sustainable fenton-like oxidation.

Making waves: Microbial-nitrate-zero valent iron/manganese synergy suppresses arsenic mobilization and greenhouse gas emissions in constructed wetlands.

Abstract The outer Van Allen radiation belt is highly dynamic in both strength and location, being driven by several distinct physical processes, making it difficult to predict for spacecraft operators. Forecasting models exist, in part, to minimise potential damage caused by this natural hazard. Both physics‐based and machine learning models exist; generally, physics‐based models allow for a deeper understanding of the system, while machine learning models offer a computationally cheap way to make a forecast, but do not always provide physical insight. We present VAMPIRE (Van Allen belt Multi‐day Predictions by Implementing a Random forest for Electrons), a pair of simple machine learning models, along with an analysis of model feature importance, to both forecast and understand the physical drivers of the outer radiation belt. We use a random forest methodology to predict whether the daily maximum ∼2 MeV electron flux and daily fluence across the entirety of the outer belt crosses the alert levels, similar to the approach used by the UK Met Office. Both models show high levels of accuracy at both nowcasting and forecasting up to a week in advance. We use feature importance to determine the most important elements of each model, and demonstrate that these models also give an insight into the major drivers of the radiation belts, and the timescales on which they have an impact.

Abstract Field‐line curvature scattering (FLCS) within the plasma sheet–to–outer radiation belt transition region (hereafter PS2ORB ) serves as a key driver of energy‐latitude dispersion in energetic electron precipitation observed at low latitudes. This precipitation forms the isotropy boundary of electrons ( IBe pattern ), located between the isotropic keV electron fluxes of the plasma sheet and the anisotropic relativistic fluxes of the outer radiation belt. During geomagnetically active periods, the PS2ORB region becomes populated with plasma sheet injections that introduce various transient electron precipitation mechanisms, significantly complicating the structure of the IBe pattern . In this study, we show that the timescales of these precipitations can reach subsecond levels, allowing them to be interpreted as microbursts. Observations of such microbursts substantially enhance the spatial and temporal variability of the IBe pattern . By combining low‐altitude ELFIN satellite measurements with high‐temporal‐resolution (40 ms) near‐UV imaging photometer data from the Pulsating Aurora Imaging Photometers System project, we separate between FLCS‐driven precipitation patterns that form the IBe pattern and electron scattering by whistler‐mode waves, which generates microbursts. We identify, for the first time, the near‐colocation of these two precipitation mechanisms within the PS2ORB region–an important feature not previously reported.

Bedaquiline, an ATP synthase inhibitor, is the spearhead of transformative therapies against drug-resistant Mycobacterium tuberculosis. Here, we use remission spectroscopy to measure the energy-transducing cytochromes within unperturbed, respiring suspensions of mycobacterial and human cells, allowing spectroscopic measurements of electron transport chains as they power living cells and respond to bedaquiline. No evidence is found for protonophoric or ionophoric uncoupling. Rather, by directly inhibiting ATP synthase, bedaquiline slows the respiratory supercomplex (Qcr:Cta; bcc:aa3) by increasing the proton-motive force, causing sub-second redirection of electron flux through the cytochrome bd oxidase (CydAB) to O2. Electron flux redirection explains the idiosyncratic bedaquiline-induced increase in O2 consumption rates previously observed. Redirection occurs as CydAB is present even in cells grown in plentiful O2. Applying the same approach to human cells did not detect bedaquiline-induced inhibition of mitochondrial function despite such inhibition being seen in isolated systems. Overall, we clarify how bedaquiline works, why different models for its action developed, and the mechanisms underlying the synergy of bedaquiline in combination regimes.

Photoelectrochemical solar water-splitting cells based on III-V tandem photoelectrodes possess the theoretical capacity to achieve >20% solar-to-hydrogen efficiency, and record devices have already approached this benchmark. However, even under constant simulated light in the laboratory, the lifetimes of the most stable devices remain insufficient. Furthermore, little is known about the effects of a real-world environment on device durability where dynamic operating conditions, such as daily and seasonal variation in the solar spectral distribution, may induce additional degradation mechanisms not seen in laboratory experiments.Tandem photoelectrodes consist of two cells that are optically and electrically in series that absorb different spectral bands according to their distinct bandgap energies. These devices are designed to evenly split the portion of the solar spectrum absorbed (i.e., half of the total photon flux goes to each junction) to achieve “matched” current for maximum efficiency. However, this condition is rarely encountered by real-world cells, and often a current mismatch restricts the overall device current to that of the current-limiting junction. The tunnel junction (TJ) between the two subcells is a layer engineered to permit holes from the top cell of a photocathode to recombine with electrons from the bottom cell. In the ideal, current-matched case the hole and electron fluxes to the TJ are equal. In reality, this is difficult to achieve, and a device limited by the top-cell current will produce a buildup of electrons at the TJ interface, while a bottom-cell current-limited device will experience a buildup of holes at this interface. In III-V tandem photoelectrodes, the TJ often consists of an Al-containing III-V alloy, and these materials are especially susceptible to corrosion in aqueous environments demonstrated by their use as the release layer in epitaxial liftoff III-V synthesis processes.1 Therefore, if the electrolyte can penetrate the top cell through pinhole defects or localized corrosion, it may destabilize the entire device by degrading the TJ. The TJ fragility in contact with electrolyte is mitigated by cathodic protection and exacerbated by an anodic bias, the condition encountered with electron accumulation or hole accumulation, respectively.After discovering stark differences in tandem photoelectrode durability that appeared dependent on which of the simulated light sources with different spectra (tungsten vs. xenon arc) was used, we hypothesized it was due to which junction was current limiting. To test our hypothesis, we fabricated samples with varied subcell thickness to further explore the relationship between the current generated by each junction and the resulting photoelectrode degradation mode. Using this material engineering strategy, we manipulated the current-limiting junction of a tandem GaInP/GaAs photoelectrode under a constant spectrum, instead of it being dictated by a dynamic spectrum. We characterized the current-limiting of each sample using incident photon-to-current efficiency measurements, and we determined photoelectrode degradation mode using chronoamperometry tests with digital microscope video recordings. We found that the oxidative instability imposed by the excess holes at the TJ in a bottom-cell-limited device further destabilizes this interface and results in rapid degradation via delamination from the TJ. These results will help inform the rational design of more durable real-world tandem photoelectrodes.1. Schermer, J. J.; Mulder, P.; Bauhuis, G. J.; Voncken, M. M. a. J.; van Deelen, J.; Haverkamp, E.; Larsen, P. K. Epitaxial Lift-Off for Large Area Thin Film III/V Devices. physica status solidi (a) 2005, 202 (4), 501–508. https://doi.org/10.1002/pssa.200460410.

Abstract Solar flares are explosive releases of magnetic energy stored in the solar corona, driven by magnetic reconnection. These events accelerate electrons, generating hard X-ray emissions, and often display quasi-periodic pulsations (QPPs) across the energy spectra. However, the energy transfer process remains poorly constrained, with competing theories proposing different acceleration mechanisms. We investigate electron acceleration and transport in a flaring coronal loop by solving a time-dependent Fokker–Planck equation. Our model incorporates transient turbulent acceleration, simulating the effects of impulsive energy input to emulate the dynamics of time-dependent reconnection processes. We compute the density-weighted electron flux, a diagnostic directly comparable to observed X-ray emissions, across the energy and spatial domains from the corona to the chromosphere. We investigate different time-dependent functional forms of the turbulent acceleration, finding that the functional form of the acceleration source maintains its signature across energy bands (1–100 keV) with a response time that is energy dependent (with higher-energy bands displaying longer response times). In addition, we find that (a) for a square pulse the switch on and off response time is different; (b) for a sinusoidal input the periodicity is preserved; and (c) for a damped sinusoidal the decay rate increases with density and higher-energy bands lose energy faster. This work presents a novel methodology for analyzing electron acceleration and transport in flares driven by time-dependent sources.