High Atmospheric Research Articles

Promise and Peril: Stellar Contamination and Strict Limits on the Atmosphere Composition of TRAPPIST-1 c from JWST NIRISS Transmission Spectra

Abstract Attempts to probe the atmospheres of rocky planets around M dwarfs present both promise and peril. While their favorable planet-to-star radius ratios enable searches for even thin secondary atmospheres, their high activity levels and high-energy outputs threaten atmosphere survival. Here we present the 0.6–2.85 μm transmission spectrum of the 1.1 R ⊕, ∼ 340 K rocky planet TRAPPIST-1 c obtained over two JWST NIRISS/SOSS transit observations. Each of the two spectra displays 100–500 ppm signatures of stellar contamination. Despite being separated by 367 days, the retrieved spot and facula properties are consistent between the two visits, resulting in nearly identical transmission spectra. Jointly retrieving for stellar contamination and a planetary atmosphere reveals that our spectrum can rule out hydrogen-dominated, ≲300× solar metallicity atmospheres with effective surface pressures down to 10 mbar at the 3σ level. For high mean molecular weight atmospheres, where O2 or N2 is the background gas, our spectrum disfavors partial pressures of more than ∼10 mbar for H2O, CO, NH3, and CH4 at the 2σ level. Similarly, under the assumption of a 100% H2O, NH3, CO, or CH4 atmosphere, our spectrum disfavors thick, >1-bar atmospheres at the 2σ level. These nondetections of spectral features are in line with predictions that even heavier, CO2-rich atmospheres would be efficiently lost on TRAPPIST-1 c given the cumulative high-energy irradiation experienced by the planet. Our results further stress the importance of robustly accounting for stellar contamination when analyzing JWST observations of exo-Earths around M dwarfs, as well as the need for high-fidelity stellar models to search for the potential signals of thin secondary atmospheres.

Molecular Dynamics Simulations of Supercritical Carbon Dioxide and Water using TraPPE and SWM4-NDP Force Fields.

The increased levels of carbon dioxide (CO2) emissions due to the combustion of fossil fuels and the consequential impact on global climate change have made CO2 capture, storage, and utilization a significant area of focus for current research. In most electrochemical CO2 applications, water is used as a proton donor due to its high availability and mobility and use as a polar solvent. Additionally, supercritical CO2 is a promising avenue for electrochemical applications due to its unique chemical and physical properties. Consequently, understanding the interactions between water and supercritical CO2 is of great importance for future electrochemical applications. Molecular dynamics (MD) simulation is a powerful tool that enables atomistic-resolution dynamics of molecular systems, which can complement and guide future experimental investigations. This study employed atomistic MD to study the cosolubilities, codiffusivities, and structure of supercritical CO2 and water systems, with a polarizable water model (SWM4-NDP) and a nonpolarizable CO2 model (TraPPE). Additionally, ab initio MD simulations were used to better understand how atomistic polarizable/nonpolarizable models compare to explicit modeling of electron densities. The polarizable water model exhibited substantial improvement in water-associated properties. We anticipate the development of a compatible polarizable CO2 model to yield similar improvement, providing a pathway for realizing novel high-pressure electrochemical systems.

A long-term drought reconstruction based on oxygen isotope tree ring data for central and eastern parts of Europe (Romania)

Abstract. This study investigates the relationship between oxygen isotope ratios (δ18O) in oak tree ring cellulose and past drought variability in Letea Forest, Romania. A δ18O site chronology spanning 1803–2020 was compiled from seven individual time series. δ18O values exhibited a significant negative correlation with moisture-related variables (cloud cover, relative humidity, and precipitation) and a positive correlation with temperature and sunshine duration. This confirms that δ18O from tree rings can be a good proxy for moisture availability. The strongest correlation was found between δ18O and the August Standardized Precipitation Evapotranspiration Index for an accumulation period of 9 months (SPEI9) for central and eastern Europe. This highlights SPEI9 as a superior indicator of drought compared to individual parameters like temperature or precipitation. Using a linear regression model, we reconstructed August SPEI9 variability for the past 200 years. The reconstruction captured interannual and decadal variations, with distinct wet and dry periods. Analysis of large-scale atmospheric circulation patterns revealed a link between high δ18O values (indicating dry conditions) and a high-pressure system over the North Atlantic. Conversely, low δ18O values (indicating wet conditions) corresponded to negative pressure anomalies over Europe. Moreover, extreme values of δ18O are also associated with the prevalence of a hemispheric teleconnection pattern, namely wave number 4. This δ18O chronology and the corresponding August SPEI9 reconstruction offer valuable tools for understanding past climate variability and its relationship with large-scale atmospheric and oceanic circulation patterns.

Processing and inspection of high-pressure microfluidics systems: A review.

In the field of microfluidics, high-pressure microfluidics technology, which utilizes high driving pressure for microfluidic analysis, is an evolving technology. This technology combines microfluidics and pressurization, where the flow of fluid is controlled by means of high-pressure-driven devices greater than 10 MPa. This paper first reviews the existing high-pressure microfluidics systems and describes their components and applications. Then, it summarizes several materials used in the microfabrication of high-pressure microfluidics chips, reviewing their properties, processing methods, and bonding methods. In addition, advanced laser processing techniques for the microfabrication of high-pressure microfluidics chips are described. Last, the paper examines the analytical detection methods employed in high-pressure microfluidics systems, encompassing optical and electrochemical detection methods. The review of analytical detection methods shows the different functions and application scenarios of high-pressure microfluidics systems. In summary, this study provides an efficient and advanced microfluidics system, which can be widely used in chemical engineering, food industry, and environmental engineering under high pressure conditions.

Assessment of Nurses' Patient Safety Culture in Primary Health Care Centers in Saudi Arabia

Purpose: Patient safety culture emphasizes strategies to prevent harm, learn from errors, and strengthen healthcare systems, nurses play a crucial role in maintaining patient safety within health facilities. Assessing patient safety culture (PSC) among nurses is essential for identifying gaps, fostering improvements, and strengthening overall care delivery. This study aims to explore nurses' perceptions of patient safety culture in the primary health care centers (PHCs) in Saudi Arabia. Materials and Methods: A cross-sectional study design was utilized to select 387 nurses employed in primary healthcare centers in Jeddah, using convenient sampling via an online survey. The Hospital Survey on Patient Safety Culture (HSOPSC) questionnaire was used to evaluate the perception of patient safety culture. Data were saved and examined utilizing SPSS Ver.26 software. Along with descriptive statistics, independent sample t-tests and ANOVA were employed to examine the significance of differences among subgroups. A p-value below 0.05 signifies statistical significance. Findings: The overall score representing nurse managers' perceptions of patient safety culture was a mean of 3.93 with a standard deviation of 0.44. Among the assessed domains, the teamwork support domain received the highest score, with a mean of 4.27 and a standard deviation of 0.587, while the nonpunitive response to error had the lowest score, with a mean of 2.44 and a standard deviation of 0.883. Nurses younger than 30 years reported a significantly lower overall score, with a mean of 3.74 and a standard deviation of 0.43. In contrast, nurses holding diplomas and those in clinical roles achieved higher scores, with means of 3.97 and 3.99, respectively, and standard deviations of 0.44 and 0.46. Scores increased notably with additional years of experience, particularly for nurses with ten or more years of experience, who achieved a mean score of 4.07 with a standard deviation of 0.62, compared to those with ten to less than fifteen years of experience, who achieved a mean score of 3.75 with a standard deviation of 0.33. The differences were statistically significant with a p-value of less than 0.001. Significant differences, also with a p-value of less than 0.001, were observed across departments. The WBC unit recorded the highest perception score, with a mean of 4.32 and a standard deviation of 0.50, followed by the X-ray unit, with a mean of 4.01 and a standard deviation of 0.33 Implications to Theory, Practice and Policy: Nurses viewed the safety culture positively in the primary health care centers. Less experienced and younger nurses indicated lower perceptions of PSC, whereas clinical nurses assessed it higher than non-clinical personnel. High-pressure areas such as the Operating Room encounter more significant PSC challenges than other departments. It is essential to create training programs that connect younger nurses with older professionals to boost their clinical confidence and safety skills, focusing on learning from errors instead of placing blame.

Advancement in Fuel Pump Design for High-Pressure Systems

Advancement in Fuel Pump Design for High-Pressure Systems

Dominance of Plastic Emission in the High Arctic Aerosol in Light Spring.

Arctic haze has attracted considerable scientific interest for decades. However, limited studies have focused on the molecular composition of atmospheric particulate matter that contributes to Arctic haze. Our study collected atmospheric particles at Alert in the Canadian high Arctic from mid-February to early May 2000. Over 100 organic species were identified in the solvent-extractable fraction by gas chromatography-mass spectrometry, which were grouped by their functional groups. Plasticizer-derived phthalates were the most abundant, followed by polyacids, sugars, sugar alcohols, biogenic SOA tracers, and fossil fuel combustion tracers. During the dark winter, major contributors to Arctic aerosols include plastic emissions, biomass burning, secondary oxidation products, and fossil fuel combustion products. In the light spring, phthalates (58-76% of the identified organics) dominated, followed by microbial and marine sources and secondary oxidation products. By employing a tracer-based method, we discovered that naphthalene and sesquiterpene oxidation products were the major contributors to SOC, and these contributions were much higher in the winter than in the spring. However, monoterpene and isoprene oxidation products peaked in light spring. Our results confirm that organic aerosols in the Arctic atmosphere are dominated by anthropogenic sources, which consist of both long-range-transported particles and combustion-emitted organics, as well as aged anthropogenic secondary organic aerosols. Despite decreasing anthropogenic pollution being replaced by natural emissions, plastic-derived pollution, represented by phthalates, increased significantly in the high Arctic atmosphere after the polar sunrise.

Delayed Impact of Biomass Burning in the Indochinese Peninsula on the Bay of Bengal Monsoon

Abstract The Indochinese Peninsula experiences a dry season with extensive biomass burning peaking from March to April. As the monsoon arrives, rainfall significantly removes aerosols through deposition, ending the emission season. However, the biomass burning aerosols exert an influence on the atmospheric circulation prior to the monsoon onset. This study employed statistical methods and a regional atmosphere–chemistry model [WRF Model coupled with chemistry (WRF-Chem)] to investigate the delayed impact of biomass burning from the Indochinese Peninsula on the monsoon onset. The results indicate that the cold sea surface temperature anomaly caused by the aerosols during the emission season can be stored in the ocean and inhibit convective activities over the adjacent sea regions in the postemission season, suppressing the southwestward cross-equatorial flow over the southern Bay of Bengal. This suppression delays the westward extension and northward shift of the upper-level South Asian high pressure system, along with its divergence and subsidence effects, thereby postponing the breakdown and retreat of the subtropical high-pressure belt. Simultaneously, the cold sea temperature also suppresses the development of a warm pool in the southeastern Bay of Bengal, which is associated with the generation of a monsoon onset vortex. Consequently, the onset of the Bay of Bengal monsoon is delayed. Due to the decreasing delayed effects of aerosols over time and the counteractive warming from the accelerated abnormal anticyclonic circulation in the upper-level Bay of Bengal, which results in accelerated disappearance of the cold signal in sea surface, the delayed influence of aerosols diminishes gradually after the onset of the Bay of Bengal monsoon until it disappears. Significance Statement This study explores the correlation between spring biomass burning in the Indochinese Peninsula and the onset of the Bay of Bengal and South China Sea monsoons. The research reveals that biomass burning during the emission season might postpone the initiation of the Bay of Bengal monsoon, while it has minimal influence on the South China Sea monsoon. By employing sensitivity experiments using models, the study elucidates the underlying mechanisms responsible for these observed effects.

Fe3O4‐doped highly electromagnetically shielded PAN‐PVP composite porous carbon films

AbstractWith the wide application of modern electronic devices, the problem of electromagnetic pollution is becoming more and more serious, and the demand for efficient electromagnetic shielding materials is becoming more and more urgent. To address this problem, we homogeneously mixed polyacrylonitrile (PAN), polyvinylpyrrolidone (PVP), and triiron tetraoxide (Fe3O4) nanoparticles by solution blending, and prepared composite precursor membranes by taking advantage of the magnetic properties and good electromagnetic loss characteristics of Fe3O4, as well as the high thermal stability and film‐forming properties of PAN and PVP. Subsequently, carbonized PAN‐PVP/ Fe3O4 composite films with different Fe3O4 contents were successfully prepared by carbonization under high temperature inert atmosphere to convert PAN and PVP into carbon materials. It was found that the PAN‐PVP/ Fe3O4 porous carbon film with 3 wt% Fe3O4 addition had a conductivity of 3.99 S·mm−1 at a thickness of 0.42 mm, and an average EMI SET of 78.9 dB, SEA of 64.8 dB, and SSEt of 1838 dB/(cm2·g−1) in the X‐band, which is a typical wave absorbing material and can meet commercial electromagnetic shielding requirements. This work provides new ideas and methods for the research and development of polymer‐based porous carbonized film as electromagnetic shielding materials.Highlights The carbon films with rich porous structure were prepared. Fe3O4 was successfully embedded into the carbon film. Carbon films have an efficient conducting network. Carbon film has excellent electromagnetic shielding performance. The main shielding mode of carbon film is absorption.

Attitude motion and nonlinear free-surface deformation of stone-skipping over shallow water

Stone-skipping is a common yet complex motion that involves rigid-body dynamics and fluid–structure interaction (FSI). While many computational fluid dynamics methods are used to simulate the interaction between a stone and fluid, little research has been done to consider the stone, fluid, and fluid boundary as a whole in a simulation. This study, focuses on the attitude motion and free-surface deformation of stone-skipping over shallow water to investigate how the boundary effect of FSI impacts ricochet behaviors. Initially, we establish an iteration framework for the stone-skipping FSI issue based on a weakly compressible smoothed particle hydrodynamics (SPH) method with a Riemann solver. We conduct particle-independence verification and simulate several cases under varying water heights. Additionally, we analyze and compare ricochets in deep and shallow cases with different incident angles and initial pitch angles. The numerical results demonstrate that in shallow flow scenarios, the “comma-shaped” high-pressure area is compressed by the stone and the fluid boundary, leading to a more moderate variation in pitch angle. Stone-skipping in shallow water typically covers a shorter distance and reaches a lower height compared to deep water cases. Changes in the incident angle show that shallow water hinders successful skipping. Futhermore, different initial pitch angles reveal that water height directly impact the stone's trajectory in both horizontal and vertical directions. These highlight the connection between motion patterns and parameters, offering a reliable numerical prediction for the stone-skipping problem using the Riemann SPH method.

Numerical simulation study of hydrogen/air flame propagation and detonation characteristics in an annular cross section of gas turbine combustion chamber

The trends and future directions of hydrogen safety research cannot be separated from the thermodynamic behavior of combustion and explosion, hydrogen spontaneous combustion, flame propagation behavior, thermodynamic mechanisms, and other related topics. In this paper, through the method of numerical simulation, considering the hydrogen flame propagation and detonation characteristics in the annular section of the combustion chamber commonly used in gas turbines, the form of detonation and detonation impact in the channel are evaluated. By discussing the deflagration to detonation transition of hydrogen/air premixed gas and premixed gas under different working conditions, it is found that the flame in the annular channel propagates close to the inner wall and forms a strong expansion and turbulence between the outer wall and the outer wall of the flame. The flame surface and the airflow shear accelerate the detonation of hydrogen. The area close to the wall on the outer side of the flame surface and the tip of the flame surface are prone to set off detonation. The high-pressure area after the detonation mainly acts on the symmetrical end face of the outer wall surface and ignition area. There is a critical working temperature to make the impact strength strongest when the detonation occurs. Reducing the equivalence ratio of the filling gas can significantly reduce the reaction speed and weaken the impact strength of the wall. When the equivalence ratio is less than a certain value, the filling gas is completely consumed in the form of deflagration.

Experimental investigation of the formation and distribution of remaining oil from pore scale to core scale during supercritical CO2 flooding

Research on the formation and distribution characteristics of remaining oil has primarily focused on individual scales, with studies at both the pore scale and core scale often lacking effective integration, particularly under supercritical conditions. In this study, a high-temperature and high-pressure microfluidic experimental system (temperature: 75 °C, pressure: 22 MPa) and micro-computed tomography (CT) scanning technology were employed to systematically investigate the formation mechanisms and distribution characteristics of five different types of remaining oil after CO2 injection. The experimental results indicate that after CO2 injection, the remaining oil mainly appears in columnar and droplet patterns, predominantly distributed in pores ranging from 4 to 13 μm, and is significantly influenced by the Marangoni effect and Jamin effect. Additionally, at the pore scale, the oil recovery increased by approximately 8.7% under high flow rates (0.5 ml/min) compared to low flow rates (0.1 ml/min); In contrast, at the core scale, the oil recovery decreased by 15.9%. This contrasting behavior can be attributed to flow non-uniformity caused by the fingering effect, which leads to uneven fluid distribution within the porous media. The comparison between pore scale and core scale provides new insights into understanding the distribution patterns of remaining oil.

Thermoelectric performance enhancement of Mg2Si-based silicides synthesized in nitrogen atmosphere

Abstract Thermoelectric materials are attractive for sustainable energy applications due to their ability to convert waste heat into electricity. However, one of the main hindrances to their widespread adoption is the stringent requirements during their synthesis and processing, and therefore affects their overall cost and sustainability. For instance, Mg-containing compounds generally requires processing in high vacuum or Argon protected atmosphere, which are less readily available. In this work, we demonstrate higher thermoelectric performance by synthesizing Mg2Si-based compounds in N2 compared to Ar atmosphere. The high performance originated from simultaneous improvement in electrical conductivity and reduced thermal conductivity. In addition, the introduction of Sn-alloying as well as Zn- and Bi- co-doping further improved both electronic and thermal transport properties, resulting in peak zT near 1.0 at 760 K for Mg1.9925Zn0.0075Si0.48Sn0.5Bi0.02. Owing to the much lower cost of N2 compared to Ar owing to their much higher relative abundance, such processing strategy is expected to reduce cost and improve sustainability. Furthermore, the insights derived from this work can potentially be applied to other compounds containing Mg- and other reactive elements. Fundamentally, this result will also motivate further studies on the intrinsic defect formation in N2 vs Ar atmosphere, which affects both electronic and thermal transports.

HYDROSTATIC TESTING TECHNOLOGIES IN THE METALLURGICAL INDUSTRY

The development of the new test presses is based on the requirements of modern technologies for the extraction of oil from ultra-deep wells and shale gas to test the strength of pipes up to higher test pressures. The hydrostatic test algorithm involves pushing test heads onto the ends of the pipe to seal the internal cavity of the pipe. Then the pipe is filled with a water emulsion and the pressure of this emulsion is increased to the value specified in regulatory documents. For high-pressure hydrostatic testing of oil and gas pipes, the most advantageous method is the external sealing of pipes using segmental sleeves. The mechanical testing equipment should take into account the compensation of axial forces from the pressure of the test fluid inside the pipe, for which purpose the press frame should be power-operated. The most common power scheme of test presses is considered, in which all axial forces arising from the action of the fluid pressure inside the pipe on the test heads are compensated by reaction forces in the power columns. The front head is rigidly connected to the columns, and the rear head is placed on a movable carriage to compensate for uneven pipe lengths. In the working position, the rear carriage is fixed to the columns with special locking mechanisms. It is advisable to improve the quality of the test by improving the design of the hydraulic system elements and studying the processes during the rise and retention of high pressure. The test pressure inside the pipe is created mainly by means of a hydraulic pressure multiplier. The parameters of the multiplier: multiplication factor, piston diameter and stroke are selected depending on the required test pressure, length and diameters of the pipes to be tested. Research on high-pressure hydraulic systems of the multiplier type is of particular interest at present.

Enhanced Photocatalytic Degradation of Environmental Pollutants Using a Triphenylamine-Based Polymer: Synthesis, Characterization, and Mechanistic Insights.

Conjugated porous organic polymers have sparked growing research attention as photocatalysts owing to their high surface area, tunable pores, and capacity to collect and transfer light energy via their delocalized backbone. However, the synthesis methods for preparing these polymers require difficult experimental setups, such as high polymerization temperature, inert atmosphere, and use of transition metal catalysts. In the present work, a triphenylamine-based conjugated porous polymer (TPA-BPA) has been synthesized employing tris(4-aminophenyl)amine (TPA) and biphenyldicarboxaldehyde (BPA) as precursors via a one-pot Schiff base reaction in ambient conditions in the absence of the metal catalyst. The synthesized TPA-BPA polymer has been characterized using Fourier transform infrared spectroscopy, 13C cross-polarization magic angle spinning nuclear magnetic resonance, Brunauer-Emmett-Teller (BET), thermogravimetric analysis, field emission scanning electron microscopy, high-resolution transmission electron microscopy, valence band X-ray photoelectron spectroscopy, X-ray photoelectron spectroscopy, cyclic voltammetry, powder X-ray diffraction, electron paramagnetic resonance (EPR), and diffuse reflectance spectroscopy (DRS) techniques. The DRS analysis revealed that TPA-BPA has an optical band gap of 2.1 eV, demonstrating its semiconductive nature. The EPR study has shown that the synthesized polymer exhibits an intense radical signal at g = 2.00, confirming free radical generation upon photoexcitation and facilitating the breakdown of organic contaminants by photocatalysis. TPA-BPA possesses an exceptional porous structure with a surface area of 36 m2/g, as confirmed by BET studies, and high thermal stability up to 420 °C. It has been confirmed by photocatalytic studies that TPA-BPA shows effective degradation of methyl orange (92%), Congo red (91.5%), tobramycin (96%), and hydroquinone (85%) under visible light irradiation in 60 min. Owing to these observations, TPA-BPA can be an excellent candidate as a photocatalyst for environmental remediation. These findings pave the way for large-scale manufacturing of metal-free conjugated porous polymers as photocatalysts with variable photoelectrical characteristics.

Research on the pressure fluctuations and hydraulic resonance phenomena in the high-pressure pipelines of marine common rail systems

Increasing injection pressures in marine high-pressure common rail systems can lead to reliability issues due to pressure fluctuations. This study investigates the mechanism of hydraulic resonance caused by these fluctuations. A test bench assessed pressure fluctuations under various conditions and fuel pipe parameters, where hydraulic resonance was observed. Time-domain and frequency-domain analyses were conducted on the test results. The system pipeline was then optimized to eliminate hydraulic resonance. Resultsindicate that pressure fluctuations exhibit both high- and low-frequency coupling. Abnormal fluctuations are caused by hydraulic resonance, triggered by the proximity between the excitation frequency of the high-pressure fuel pump and the first-order natural frequency of the system. Resonance speed is influenced by the fuel pipe's structural parameters and the fuel's hydraulic properties. The frequency-domain model shows high predictive accuracy, identifying the interface between the pump and the pipeline as the most probable failure location. Optimization reduced pressure fluctuations at the pump end and the common rail by 73 % and 35.7 %, respectively, and eliminated hydraulic resonance at the original resonance speed. The maximum pressure fluctuation amplitude at the pump end decreased from 410 bar to 167 bar, a 59.3 % reduction. The research methodology presented in this paper provides a theoretical foundation for the structural design of the high-pressure pipeline in high-pressure common rail systems.

Electromagnetic Coils for a 3000 Psi Hydraulic MEMS Valve Assembly

Electromagnetic coils serve many roles in MEMS technologies such as actuators, microfluidics, sensors, energy harvesting, wireless communication, inductive heating, and biomedical applications. Coils can be made using traditional semiconductor manufacturing techniques requiring near UV lithography to define photoresist molds, electroforming metal into the molds, chemical mechanical planarization, assembly, and packaging. Non-traditional techniques such as LIGA using x-rays and soft LIGA using near UV exposures can create higher aspect ratio structures therefor maximizing coil performance and minimizing coil size.Our work explores micro-fabrication techniques using soft LIGA lithography to create single sided and double-sided copper electroformed MEMS coils. The target coil feature sizes are 100+ micron in thickness of copper, 50 micron feature size, 50 micron gaps, and millimeters in total form factor. The microfabrication process including lithography, copper electrodeposition, and through wafer vias will be discussed along with lessons learned to meet the design criteria. Our goal is the demonstration of a single sided coil and double-sided coil device that could be assembled and arrayed across a 6 inch silicon wafer microfabrication process to create a hydraulic valve assembly. This would enable a digital flow control high-pressure hydraulic valve system capable of reaching 3000 psi. Ultimately this goal minimizes size and weight while increasing efficiency and maximizing power. The figure below depicts a cross sectional view of a single sided coil design assembled with a device layer having a through-wafer etch flow path.Figure 1: Cross sectional view showing a single hydraulic MEMs valve assembly. A single sided MEMs coil on top, a suspended spring able to open and close the valve, and a thru-wafer fluid flow path. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. Figure 1

Proton-Conducting Solid Oxide Electrolysis Cells with Scandia-Doped Barium Zirconate Electrolytes

Proton-conducting solid oxide electrolysis cells (P-SOECs) leverage their low activation energy for proton-conduction to achieve high water electrolysis performance in the intermediate temperature regime (400-600°C). In this sought after temperature zone critical challenges that face high-temperature systems (>700°C) such as balance-of-plant costs, degradation, and oxidation may be alleviated while still retaining favorable reaction kinetics with earth-abundant materials. The electrolyte in P-SOECs plays a vital role in full cell performance and efficiency. P-SOEC electrolytes must have high ionic conductivity, low electronic conductivity, and exceptional durability in high steam atmospheres. Yttrium-doped barium zirconate (BZY) and yttrium/ytterbium co-doped barium cerate zirconate (BZCYYb) are the most widely used P-SOEC electrolyte materials to date. However, practical applications for these materials are in question due to the low protonic conductivity of BZY, poor durability of BZCYYb in high steam environments, and the depressed faradaic efficiencies achieved by P-SOECs utilizing these electrolytes. In this work we show that scandium-doped barium zirconate (BZSc) is a promising electrolyte material to produce P-SOECs with a combination of high performance, efficiency, and durability. Relevant electrolysis current densities were attained below 500°C and long-term durability is demonstrated. Cell architecture and operating conditions are optimized to maximize faradaic efficiency. Our results indicate that high proton concentrations in the electrolyte achieved through high dopant levels can boost performance in barium zirconate-based P-SOECs while preserving unrivalled durability. This work demonstrates the potential for BZSc as an effective P-SOEC electrolyte and we anticipate future studies to further characterize BZSc. Furthermore, this work opens the door for more research into proton conducting materials with dopant levels exceeding 20 mol%.

A pressure-jump EPR system to monitor millisecond conformational exchange rates of spin-labeled proteins.

Site-directed spin labeling electron paramagnetic resonance (SDSL-EPR) using nitroxide spin labels is a well-established technology for mapping site-specific secondary and tertiary structure and for monitoring conformational changes in proteins of any degree of complexity, including membrane proteins, with high sensitivity. SDSL-EPR also provides information on protein dynamics in the timescale of ps-μs using continuous wave lineshape analysis and spin lattice relaxation time methods. However, the functionally important time domain of μs-ms, corresponding to large-scale protein motions, is inaccessible to those methods. To extend SDSL-EPR to the longer time domain, the perturbation method of pressure-jump relaxation is implemented. Here, we describe a complete high-pressure EPR system at Q-band for both static pressure and ms-timescale pressure-jump measurements on spin-labeled proteins. The instrument enables pressure jumps both up and down from any holding pressure, ranging from atmospheric pressure to the maximum pressure capacity of the system components (~3500 bar). To demonstrate the utility of the system, we characterize a local folding-unfolding equilibrium of T4 lysozyme. The results illustrate the ability of the system to measure thermodynamic and kinetic parameters of protein conformational exchange on the ms timescale.

Canadian record-breaking wildfires in 2023 and their impact on US air quality

In recent years, extreme climate has increasingly triggered record boreal wildfires. The year 2023 saw a significant surge in wildfire occurrences in Canada, far surpassing the historical record. In this study, multi-source data were utilized for a comprehensive analysis of the development of the Canadian wildfires in 2023, the pathways of wildfire smoke, and its impact on the air quality in the US. The results indicate that the 2023 Canadian wildfires mainly occurred in western Canada (accounting for 60% of the burned area) and Quebec (eastern Canada, 29% of the burned area). Weather systems played a key role throughout wildfires and smoke plume transport processes. Specifically, high temperatures and dry weather caused by the blocking high-pressure systems was conducive to the enhancement of wildfire activities. Additionally, the southward airflow ahead of the ridge facilitated the transport of wildfires plume towards the south. This transport pattern frequently manifests under the Weather Regimes (WR) associated with the Alaskan Ridge (AkR) and Arctic High (ArH). In May and July, the smoke originating from the wildfires in western Canada, guided by the North American trough, affected the midwestern US. In June, smoke from eastern Canada led to severe air pollution in the northeastern US. Throughout the wildfire season, particulate matter dominated pollution in the US. The daily average PM2.5 concentration peaked at 258.9 μg/m³, exceeding the World Health Organization standard guidelines (15 μg/m³) by 17.3 times. This study highlights that wildfire has become one of the major environmental challenges facing the world under the influence of extreme climate.