Sustaining Surface Lithiophilicity of Ultrathin Li-Alloy Coating Layers on Current Collector for Zero-Excess Li-Metal Batteries.

Zero-excess Li-metal batteries (ZE-LMBs) have emerged as the ultimate battery platform, offering an exceptionally high energy density. However, the absence of Li-hosting materials results in uncontrolled dendritic Li deposition on the Cu current collector, leading to chronic loss of Li inventory and severe electrolyte decomposition, limiting its full utilization upon cycling. This study presents the application of ultrathin (≈50 nm) coatings comprising six metallic layers (Cu, Ag, Au, Pt, W, and Fe) on Cu substrates in order to provide insights into the design of Li-depositing current collectors for stable ZE-LMB operation. In contrast to non-alloy Cu, W, and Fe coatings, Ag, Au, and Pt coatings can enhance surface lithiophilicity, effectively suppressing Li dendrite growth, thereby improving Li reversibility. Considering the distinct Li-alloying behaviors, particularly solid-solution and/or intermetallic phase formation, Pt-coated Cu current collectors maintain surface lithiophilicity over repeated Li plating/stripping cycles by preserving the original coating layer, thereby attaining better cycling performance of ZE-LMBs. This highlights the importance of selecting suitable Li-alloy metals to sustain surface lithiophilicity throughout cycling to regulate dendrite-less Li plating and improve the electrochemical stability of ZE-LMBs.

Reimagining a pass/fail clinical core clerkship: a US residency program director survey and meta-analysis.

Pass/fail (P/F) grading has emerged as an alternative to tiered clerkship grading. Systematically evaluating existing literature and surveying program directors (PD) perspectives on these consequential changes can guide educators in addressing inequalities in academia and students aiming to improve their residency applications. In our survey, a total of 1578 unique PD responses (63.1%) were obtained across 29 medical specialties. With the changes to United States Medical Licensure Examination (USMLE), responses showed increased importance of core clerkships with the implementation of Step 2CK cutoffs. PDs believed core clerkship performance was a reliable representation of an applicant's preparedness for residency, particularly in Accreditation Council for Graduate Medical Education's (ACGME)Medical Knowledge and Patient Care and Procedural Skills. PDs disagreed with P/F core clerkships because it more difficult to objectively compare applicants. No statistically significant differences in responses were found in PD preferential selection when comparing applicants from tiered and P/F core clerkship grading systems. If core clerkships adopted P/F scoring, PDs would further increase emphasis on narrative assessment, sub-internship evaluation, reference letters, academic awards, professional development and medical school prestige. In the meta-analysis, of 6 studies from 2,118 participants, adjusted scaled scores with mean difference from an equal variance model from PDs showed residents from tiered clerkship grading systems overall performance, learning ability, work habits, personal evaluations, residency selection and educational evaluation were not statistically significantly different than from residents from P/F systems. Overall, our dual study suggests that while PDs do not favor P/F core clerkships, PDs do not have a selection preference and do not report a difference in performance between applicants from P/F vs. tiered grading core clerkship systems, thus providing fertile grounds for institutions to examine the feasibility of adopting P/F grading for core clerkships.

Comparative Study of Sampling and Measurement Methods for the Development of CH4 Emission Factors at MSW Incinerators.

Lung samplers (periodic sampling) have generally been used to develop CH4 emission factors in waste incineration facilities. Since this method must be calculated using only the value at a specific point in time, it may not reflect the emission characteristics depending on the circumstances of the facility. In order to supplement this method, a method of continuously collecting samples for a long period of time or continuously measuring may be used. In this study, the CH4 emission factor development and titration methodology were reviewed using both the existing methods and the newly proposed continuous sampling and continuous measurement methods. As a result of the analysis, the average emission factor by periodic sampling was 0.201 gCH4/ton-waste, the average emission factor by continuous capture was 0.199 gCH4/ton-waste, and the average emission factor by continuous measurement was 0.176 gCH4/ton-waste. There was a difference of 0.025 gCH4/ton-waste in the emission factor values by periodic sampling and continuous measurement, and the emission factor values for periodic sampling and continuous sampling were similar. There was no statistically significant difference, confirming that all three methods could be used. However, the existing method, periodic sampling, cannot reflect the characteristics of the night, and, in the case of continuous measurement, expensive equipment and maintenance are difficult. Therefore, it is judged that the method using continuous sampling is a good method that can combine the two advantages.

Study on Enhanced Methods for Calculating NH3 Emissions from Fertilizer Application in Agriculture Sector.

Ammonia is a representative PM-2.5 secondary product, and the need for management is emerging as health and living damage caused by fine particulate matter worsens. The main source of ammonia is the agricultural sector, and in Korea, 79% of the total ammonia emissions are emitted from the agricultural sector. Among them, there is high uncertainty about how to calculate emissions from ammonia discharged from fertilizer use, and inventory in the U.S. and Europe is borrowed, so inventory needs to be improved according to the situation in Korea. In this study, the ammonia inventory in the agricultural sector in Korea and abroad was examined, and additional activity data that can be used were reviewed. In addition, in order to improve the emission calculation method, the emission was calculated in three ways by different factors. As a result, it was confirmed that the amount of discharge varies depending on the type of soil use or whether cultivated crops are considered, and the possibility of excessive fertilizer top-dress by farmers was confirmed. In order to calculate the emission at a more detailed level based on this study, basic data such as fertilizer input method and regional distribution of crops should be systematically collected, and related follow-up studies should be conducted.

Mixed Use of Bio-Oil in Oil Power Plants: Should It Be Considered When Developing NH3 Emission Factors?

In order to cope with recent climate change, Korea is reducing the use of heavy oil in petroleum-fired power plants and mixing bio-oils. Accordingly, this must be taken into account when calculating the emissions of air pollutants. However, in the case of Korea, when calculating NH3 emissions, the United States Environmental Protection Agency (EPA) emission factor is applied as it is to calculate emissions, and for petroleum power plants, the heavy oil emission factor proposed by EPA is used as it is to calculate emissions. In petroleum power plants, bio-oil is not mixed in a certain amount and used at a different ratio depending on the situation of the power plant. Therefore, in this study, the NH3 emission factor according to the mixing ratio of bio-heavy oil is calculated and the mixing ratio is calculated. As a result of the analysis, the emission factor according to bio-oil and the mixed ratio was found to be in the range of 0.010~0.033 kg NH3/kL, and it was lower than the heavy oil emission factor 0.096 kg NH3/kL of EPA currently used in Korea. This is because the amount of NH3 through the slip is also small since the use of NH3 for reduction is also low because the NOx emission from the use of bio-oil is low. Considering all of these points, we have statistically analyzed whether emission factors should be developed and applied. As a result of the confirmation, the difference according to the mixed consumption rate was not large.