Microscale (United States)

Developing sustainable biobased alternatives is imperative not only to address mounting environmental concerns but also to overcome the intrinsic limitations of conventional petroleum-derived optical films in next-generation displays. However, conventional biobased materials like cellulose triacetate suffer from restricted optical tunability (typically negative C-plate behavior). Herein, we fabricate high-performance optical films from naturally sourced cellulose by benzoate substitution with controlled degrees of substitution (DS) from 0.89 to 3.00, using a homogeneous ionic liquid platform. By systematically investigating the “structure-processing-property” relationships, we reveal a distinct nonmonotonic “V-shaped” dependence of birefringence on DS. Crucially, we identify a steric-hindrance-driven orientation flip of the benzoyl side groups, which enables the precise tailoring of optical properties: from a “zero-birefringence” state at DS ≈ 1.55 to specific Negative Retro-Zero characteristics (nx > nz > ny) for 1.55 < DS < 2.59, and finally to positive C-plate behavior at DS > 2.59. The precise control over birefringence achieved in this work broadens the applicability of cellulose derivatives and paves the way for the design of advanced materials for next-generation display technologies.

Developing sustainable strategies for ambient ammonia synthesis is a critical challenge in materials science and catalysis. While bioinorganic hybrid systems have emerged as a promising solution by combining the light-harvesting efficiency of semiconductors with the catalytic specificity of biological nitrogenases, balancing material toxicity with electron transfer efficiency remains a major bottleneck. In this study, we constructed a robust and biocompatible inorganic-bacterial hybrid system via the in situ binding of magnetite (Fe3O4) nanoparticles (NPs) to whole-cell microorganisms. In this architecture, Fe3O4 NPs function as photosensitizers that capture solar energy to generate photoexcited electrons. These electrons are efficiently transferred to the attached Azotobacter vinelandii (A. vinelandii), thereby supplementing the intracellular electron pool. This continuous exogenous electron supply significantly boosts the energy conversion efficiency and nitrogenase activity within the biohybrid. This study underscores the potential of nanobiohybrid systems in solar-to-chemical energy conversion and paves the way for the sustainable production of diverse functional chemicals utilizing solar energy.

Electrocatalytic reduction of CO2 to methane is one of the effective strategies for achieving carbon cycling and addressing environmental issues. Herein, we report the successful synthesis of an atomically precise Cu58 nanocluster. An optimized one-pot method involving sequential sodium borohydride reduction was developed. The crystal structure of the Cu58 nanocluster belongs to the space group Pca21 and features a central distorted face-centered cubic Cu14 kernel encapsulated within a Cu48S36P4 shell. This shell is composed of Cu7S2 and Cu10S8P2 units and is flanked by two peripheral Cu5S5P staple motifs. ESI-MS confirms the molecular formula, and XPS analyses establish that copper exists exclusively in the Cu+ oxidation state. The catalytic performance of Cu58 was evaluated for electrochemical CO2 reduction (CO2RR) upon dispersion on a C3N4 support. 15-Cu58/C3N4 achieves a CH4 Faradaic efficiency of 73% at 600 mA cm–2. The synergy between the topology structure of Cu58, the Cu+ sites of the nanocluster, and the pyridinic N sites of the C3N4 support is identified as the key factor for enhancing CO2 adsorption and suppressing the competing hydrogen evolution reaction, thereby steering the selectivity toward methane. This study underscores the potential of structurally defined copper nanoclusters as the premier electrocatalysts for fuel production.

Abstract. Accurate evaluation of both observations and forecasts is essential for advancing atmospheric composition research and improving operational prediction. Traditionally, this has relied on separate workflows with product-specific preprocessing, often limiting reproducibility and creating inconsistencies between models and observational datasets or across different products. Modern data assimilation systems provide precise observation operators for mapping model variables into observation space, yet these capabilities remain underutilized outside assimilation. Here, we demonstrate how the Joint Effort for Data assimilation Integration (JEDI) framework addresses this gap by offering a unified, modular, and model-agnostic system that integrates data assimilation with systematic evaluation. JEDI enables consistent intercomparisons of observations, forecasts, and reanalyses by interfacing with diverse forecast models and gridded datasets, while leveraging carefully designed observation operators to compute equivalent quantities for a wide range of observation products. These include satellite instruments such as Tropospheric Emissions: Monitoring of Pollution (TEMPO), The TROPOspheric Monitoring Instrument (TROPOMI), Moderate Resolution Imaging Spectroradiometer (MODIS), Visible Infrared Imaging Radiometer Suite (VIIRS), and Plankton, Aerosol, Cloud, and ocean Ecosystem (PACE), as well as ground-based networks like Aerosol Robotic Network (AERONET), Pandora, and U.S. Environmental Protection Agency (EPA) AirNow. Case studies illustrate the flexibility of this workflow: (1) NO2 forecasts from the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) evaluated against TEMPO, TROPOMI, and Pandora retrievals; (2) surface fine particulate matter and ozone forecasts from WRF-Chem assessed against AirNow measurements using EPA regulatory thresholds; and (3) aerosol optical depth (AOD) retrievals from multiple satellites compared with Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) and validated against AERONET. These examples highlight JEDI’s ability to detect systematic regional biases, reconcile complementary sampling characteristics across platforms, and assess the added value of unified observation operators for cross-comparison. Overall, JEDI provides a consistent and extensible framework for model validation and observation assessment, reducing redundant preprocessing and aligning evaluation with operational data assimilation practices, and ultimately advancing both research and operational applications in atmospheric composition.

Great technical advances have been achieved since the first atom-trap trace analysis (ATTA) -based radiokrypton application in Egypt, where 1 Myr old groundwater was discovered. Beyond advances in ATTA measurement capabilities, including reduction in sample size, analysis duration, and analytical uncertainty, major progress has been achieved over the past two decades in the sample collection and preparation techniques. These advances paved the expansion of ATTA-based noble gas applications to many other aquifers worldwide, illuminating the nature and flow pattern of deep groundwater systems. While the potential of this new analytical technique for old groundwater dating is well recognized, another important aspect yet to be examined is the reproducibility of radiokrypton in aquifers over time, i.e., how representative is a discrete groundwater sample, collected at a specific time and location, for the natural groundwater system? The likelihood of a negative answer is increased by flow-field disturbance in aquifers following massive groundwater abstraction. Here, we present repeated 81Kr sampling and measurements in twenty-one sites over Israel, mostly of deep (up to 1 km) wells tapping confined aquifers in the arid to hyperarid Negev desert. The results demonstrate that radiokrypton measurements are indeed reproducible, even in cases where samples were collected as long as nine years apart and from highly productive (∼1 Mm3/yr order) pumping wells. Furthermore, many of the repeated measurements in this study (17 out of the 21 sites) were conducted with different ATTA Instruments in two different laboratories using slightly different sampling, preparation, and analysis techniques, yet with an overall good agreement. The consistency in the ATTA-based 81Kr-dating results over time highlights the robustness of this state-of-the-art technique as a tool to unravel groundwater flow patterns and encourages further applications to many other yet-to-be-explored deep aquifers.

The one-dimensional side gate based on graphene edges shows a significant capability of reducing the channel length of field-effect transistors, further increasing the integration density of semiconductor devices. The nanoscale electric field distribution near the edge provides the physical limit of the effective channel length; however, its imaging under ambient conditions is still lacking, which is a critical aspect for the practical deployment of semiconductor devices. Here, we used scanning nitrogen-vacancy (N-$V$) microscopy to investigate the electric field distribution near edges of single-layer graphene. Real-space scanning maps of photocharged floating graphene flakes were acquired with a spatial resolution of approximately 10 nm, and the electric edge effect was quantitatively studied by analyzing the N-$V$ spin energy-level shifts due to the electric Stark effect. Since the graphene flakes are isolated from external electric sources, we brought out a theory based on the photothermionic effect to explain the charge transfer from graphene to the oxygen-terminated diamond probe with a disordered distribution of charge traps. Real-time tracing of electric fields detected the photothermionic emission process and the recombination process of the emitted electrons. This study provides a perspective for graphene-based one-dimensional gates and optoelectronics with nanoscale real-space imaging and, moreover, offers a method to tune the chemical environment of diamond surfaces based on optical charge transfer.

Three-dimensional electron diffraction (3DED) is a powerful technique providing for crystal structure solutions of sub-micron sized crystals too small for structure determination via X-ray techniques. The entry requirement, however, of a transmission electron microscope (TEM) adapted with bespoke software for coordinated sample stage rotation and continuous electron diffraction data acquisition has generally inhibited the wider uptake of 3DED. To address this limitation, we present novel software GiveMeED appropriate for controlled 3DED data acquisition. The collection of useable reflections beyond 0.8 {\AA} makes 3DED crystallographic processing effectively routine, using standard software and workflows derived from single-crystal X-ray diffraction (SCXRD) techniques. A full experimental workflow for 3DED on a conventional TEM is described in practical terms, in combination with direct imaging, and energy dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS), for the return of comprehensive correlative descriptions of crystal morphologies and sample compositions, with due regard for the quantification of electron flux at each stage of the characterisation process. The accuracy and effectiveness of GiveMeED is demonstrated through structure solutions for case study paracetamol, copper(II) phthalocyanine, and percholorocoronene samples, characterised in their near-native states under controlled low dose conditions at either room or cryogenic temperatures, with determined unit cell parameters and atomic connectivity matching accepted literature X-ray structures for these compounds. To promote the wider adoption of 3DED, we make GiveMeED freely available for use and modification, in support of greater uptake and utilisation of structure solution procedures via electron diffraction.

Gasotransmitters, including nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S), are critically involved in a broad spectrum of physiological and pathological processes, such as vasodilation, neurotransmission, immune modulation, and antioxidant defense. Due to their diverse biological activities, these gasotransmitters have attracted increasing interest as potential therapeutic agents. However, their clinical application remains limited by intrinsic physicochemical challenges, including short half-lives and low targeting specificity, which complicate efficient delivery. In recent years, oral delivery approaches have received growing attention in gasotransmitter-based therapy owing to their noninvasive administration, high patient compliance, and potential for both systemic and localized effects. Polymer-based delivery systems play a pivotal role in the oral administration of gasotransmitters by enabling controlled release, protecting labile molecules from degradation, and enhancing their bioavailability. This Review systematically summarizes recent advances in the oral delivery of NO, CO, and H2S, with particular emphasis on prodrug design, controlled release systems, carrier engineering, and in vivo release mechanisms. Furthermore, the major technological barriers to clinical translation are critically discussed. Finally, future perspectives are outlined to inform the rational design of optimized oral delivery platforms for therapeutic gases.

Two-dimensional (2D) ternary transition metal chalcogenides (TMCs) are promising for thermoelectric (TE) applications because of their low structural symmetry, high in-plane anisotropy, and adjustable band gap. A high-performance TE material requires high electrical conductivity, a large power factor PF, and a sizable dimensionless figure of merit ZT. This study focuses on the TE properties, including electrical and phonon transport properties, of highly in-plane anisotropic 2D-ZrGeTe4 based on combined first-principles and semiclassical Boltzmann theory. First, our results prove that 2D-ZrGeTe4 is mechanically, dynamically, and thermodynamically stable as a free-standing monolayer, which can be attributed to the van der Waals nature of ZrGeTe4. Next, we show that ZrGeTe4 exhibits a tunable band gap, exhibiting an indirect-to-direct band gap transition from the 3D bulk to the 2D monolayer. The electron and hole mobilities are highly anisotropic and dominate in the x-direction. Furthermore, 2D-ZrGeTe4 exhibits a large PF and low lattice thermal conductivity, yielding a high theoretical ZT of 6 and 3 for n-type and p-type at 900 K, respectively. Owing to its rich anisotropy, band degeneracy capabilities, and extreme phonon anharmonicity, 2D-ZrGeTe4 could emerge as a promising candidate for advanced TE applications at high-temperature ranges.