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Spatial Atomic Arrangement of Cyclohexyl-Based Ligands for Enhanced Interface Passivation in 2D/3D Perovskite Solar Cells
No full textMetal halide perovskite solar cells (PSC) have emerged as a promising candidate for next-generation photovoltaic technologies, achieving remarkable power conversion efficiencies (PCE) in polycrystalline thin-films. Nonetheless, their PCE and long-term stability are often limited by a high density of defects at interfaces and grain boundaries. One effective strategy to mitigate these issues is forming 2D/3D heterojunction structure by introducing a surface-passivating interfacial layer of quasi-2D Ruddlesden-Popper perovskite (RPP) with various functional ligand molecules. In this study, hydroxyl-functionalized cyclohexyl ammonium hydrochloride (ACHACl) is employed as the ligand molecule, which features dual functional groups. A comparative analysis reveals that cis-configurations of the ligands exhibit enhanced adsorption on the [PbI6]4- octahedra in lead halide perovskites, enabling more effective passivation of defects including metallic Pb0 on 3D perovskite thin-films. Moreover, the 2D/3D structure incorporating the RPP improves hole extraction to the hole transport layer (HTL) by inducing an upward shift in the valence band edge. Consequently, the 2D/3D heterojunction PSCs achieve a PCE of 23% under 1-Sun illumination, along with significantly improved long-term stability, presenting the critical role of tailoring the atomic structure of the RPP ligand molecules to boost both the efficiency and long-term stability of PSCs.N
US-South Korea Nuclear Sharing: A Middle Path to Increase Security on the Peninsula
No full textSince North Koreas first nuclear weapons test in 2006, its threat to South Korea has grown significantly. This article assesses South Koreas changing threat environment and explores its options for strengthening deterrence. We make three key arguments. First, South Koreas concerns about the state of deterrence on the Peninsula are well founded with growing nuclear dangers and declining credibility of the US extended deterrent. Second, leaders in South Korea have options for responding to these growing threats. Third, one of these options—a nuclear sharing agreement with the US—offers a sensible middle course. Nuclear sharing represents a compromise between the status quo (which leaves South Korea dependent on questionable US extended deterrence) and acquisition of independent capabilities (which may entail high political and economic costs)
Targeting NADPH Oxidase with APX-115: Suppression of Platelet Activation and Thrombotic Response
No full textAims: NADPH oxidase (NOX)-derived reactive oxygen species (ROS) are critical for platelet activation and thrombus formation. We hypothesized that inhibiting NOX-mediated ROS production with a pan-NOX inhibitor, APX-115, could effectively suppress platelet activation and thrombus formation, potentially serving as a novel antiplatelet therapeutic. This study aimed to explore the effects of APX-115 on human platelet functional responses and ROS-mediated signaling pathways.Results: APX-115 inhibited intracellular and extracellular ROS production in collagen-stimulated platelets, suppressing aggregation, P-selectin exposure, and ATP release. By preserving protein tyrosine phosphatase activity, APX-115 reduced tyrosine phosphorylation-dependent pathways inhibition, including spleen tyrosine kinase, LAT, Vav1, Bruton's tyrosine kinase, and phospholipase C gamma 2, leading to decreased PKC activation and calcium mobilization. APX-115 also suppressed collagen-induced integrin alpha IIb beta 3 activation, accompanied by elevated cGMP and vasodilator-stimulated phosphoprotein phosphorylation levels. In addition, APX-115 reduced p38 MAPK and ERK5 activation, leading to diminished phospholipase A2 phosphorylation, thromboxane production, and the exposure of procoagulant phosphatidylserine. These inhibitory effects extended to thrombus development caused by platelet adherence under shear and arterial thrombosis without prolonging bleeding time in murine models.Innovation: This study is the first to demonstrate that APX-115 inhibits NOX-mediated ROS production, platelet activation, and thrombus formation. By uncovering its effects on collagen receptor glycoprotein VI-mediated pathways, the work highlights the promise of APX-115 as an antiplatelet and antithrombotic agent.Conclusion: Our findings highlight the therapeutic potential of APX-115 in treating thrombotic and cardiovascular disorders by targeting NOX-mediated ROS production to mitigate platelet hyperreactivity and thrombus formation. Antioxid. Redox Signal. 00, 000-000.N
Comparative efficacies of iron oxide-modified biochar and pyrite-modified biochar for simultaneous passivation of cadmium and arsenic in aqueous solutions and lettuce (Lactuca sativa. L) cultivation
No full textEffective simultaneous passivation of cationic (Cd) and anionic (As) heavy metal (metalloids) still is a critical environmental challenge. In this study, rice husk biochar was ball-milled with iron-based materials magnetite (Fe3O4) and pyrite (FeS2), then re-pyrolyzed at 600(o)C to produce modified biochars Fe3O4-BC and FeS2-BC respectively. Short-term removal performance was evaluated after 24 h adsorption in dual-element aqueous systems where Fe3O4-BC displayed Cd (99.62%) and As (62.39%) removal, and FeS2-BC displayed Cd (81.73%) and As (55.54%) removal, and BC displayed Cd (99.04%) and As (54.31%) removal. Tessier and Wenzel sequential extraction of Cd and As sorbed biochar solids revealed both modifications led to enhanced immobilization mechanisms (precipitation and complexation) absent in unmodified BC. XRD and FTIR spectra identified heavy metal precipitates and surface complexation respectively. Sorbed Cd, As was visualized with SEM-EDS. Long-term passivation effects were studied in co-contaminated soil systems with 1% (w/w) treatment with biochars, quantifying> soil-to-plant heavy metal translocation by bioconcentration factors in lettuce plant, shoot, and root. Differing passivation superiority was observed for each individual metal, where Fe-,Fe-3,Fe-,O,(,4,),-BC treatment led to lowest plant Cd BCF (70.77%) while FeS,(,2,),-BC treatment resulted in lowest plant As BCF (65.72%),. Interestingly, in comparison to the control, application of unmodified BC led to,increased plant As BCF (101.03%),, suggesting biochar modification with inorganic iron materials leads to increased long-term stability by decelerating DOC release. Overall, Fe3O4-BC treatment appeared most effective in countering simultaneous Cd and As accumulation in edible lettuce portions,displaying shoot Cd BCF (35.33%) and shoot As BCF (9.17%).N
A Study on the Meaning of Xing(興) in Du Fus Poetry
No full text興은 중국 고전시에서 매우 중요하고 논란이 많은 개념이다. 흥은 起의 의미에서 출발하여 후대에 수사 기교인 譬喩(比興)와 내용상의 情感의 뜻이 혼용되었다. 흥은 일반적으로 풍류 있고 흥겨운 감정, 興致의 의미로 많이 이해된다. 하지만 이로써는 杜甫 詩의 흥을 제대로 이해할 수 없다. 본고는 두보 시에서 興이 단순히 동사 起의 의미인 것을 제외하고 명사로 쓰인 것을 살펴보았다. 시의 본문에 쓰인 흥에서 比興의 의미인 것은 1번밖에 없으며, 다양한 감정을 표현한 것이 대부분이다. 이 중에 道가 사라지면 시가 흥을 발한다(道消詩發興), 흥을 푸는 데는 시만한 것이 없다(遣興莫過詩), 흥을 타면 곧 집이다(乘興卽爲家)가 주목할 만하다. 여기에서 두보 시의 흥의 발생 원인, 해소 방법, 그 결과를 알 수 있다. 이러한 두보 시의 흥의 내용은 제목에 흥이 나타난 것에서 보다 구체적으로 볼 수 있다. 다수의 「흥을 풀다(遣興)」 연작시가 그 대표적인 예이다. 여기서 두보는 온갖 감정을 다 흥이라 표현하고 있는데, 주로 불우하고 슬픈 감정을 흥으로 포괄하고 있는 것이 특징적이다. 이는 두보 이전과 이후의 다른 시인들의 시에 표현된 흥과 비교해봐도 확연히 차이가 있다.N
Quantitative Evaluation and Effect Analysis of Green Infrastructure Strategies for Urban Heat Island Mitigation in Vulnerable Areas of Daegu City
No full text본 연구는 대구광역시 인동촌 지역을 대상으로 도시 열섬현상을 완화하기 위한 그린 인프라스트럭처 전략의 정량적 효과를 전산유체역학 기반으로 분석하였다. 기후변화와 도시 산업화로 인한 도시 열섬현상이 심각해짐에 따라, 도시 열 환경 개선을 위한 다양한 자연 기반 해법 및 그린 인프라스트럭처 전략이 주목받고 있다. 본 연구에서는 옥상 녹화 시설을 주요 그린인프라로 선정하고, 전산유체역학 모의 분석을 통해서 도시 열섬 저감 효과를 평가하였다. 대상지인 대구시 인동촌 지역을 3차원 모델로 구축하고, 온도와 상대습도 변수 변화에 따른 옥상녹화의 온도 저감 효과를 분석하였다. 연구 결과, 입력되는 상대습도가 30%일 때 옥상녹화는 평균 0.9℃의 온도 저감 효과를 나타냈으며, 상대습도가 90%로 증가할 경우 온도 저감 효과는 평균 0.68℃로 감소하였다. 또한, 입력 기온이 33℃에서 40℃로 상승함에 따라 온도 저감 효과는 0.62℃에서 0.9℃로 증가하는 경향을 보였다. 이러한 결과는 증발산 효과가 저온 및 고습 환경에서는 제한적이지만, 고온 및 저습 환경에서 더욱 뚜렷하게 나타나는 기존 연구결과와 일치하는 결과를 보였다. 본 연구는 도시 열섬 저감 효과를 극대화할 수 있는 지역 맞춤형 기후변화 전략 수립에 기여할 수 있을 것으로 기대하며, 향후 더 다양한 기후변화 전략 수립과 기후 시나리오를 활용한 연구가 필요할 것으로 판단된다.N
Modeling Artistic Competencies for University Students to Cultivate Convergence Talents
No full text목적 본 연구는 융합인재 육성을 위해 대학생에게 요구되는 예술역량의 구성요소를 체계적으로 규명하고, 각 구성요소의 하위요인을 도출하여 예술 기반 융합 교육의 이론적 토대를 마련하고자 하였다.
방법 연구의 목적을 달성하기 위해, 본 연구는 첫째, 선행연구 고찰을 통해 국내외 예술역량 관련 연구들을 분석하여 총 245개의예비 역량 풀을 구성하였으며, 이를 바탕으로 예술핵심역량 5개의 역량 군과 72개의 하위역량을 도출하였다. 도출된 역량 모델의타당성을 검증하기 위하여 2회차의 델파이를 시행하였으며, 분석된 결과를 바탕으로 최종역량 모델을 도출하였다.
결과 델파이 조사 결과, '미적 통찰', '비판적 성찰', '융합적 문제해결', '창의적 사고', '협력적 실행'의 5개 예술핵심 역량 군이 도출되었다. 또한 각 역량 군별로 구체적인 하위역량이 도출되어 최종적으로 미적 통찰(7개), 비판적 성찰(8개), 융합적 문제해결(9개), 창의적 사고(8개), 협력적 실행(5개) 등 총 37개의 하위역량이 확정되었다.
결론 본 연구는 대학에서의 예술교육을 통한 융합인재 육성의 관점에서 예술역량의 구성요소를 체계화하고, 각 역량의 의미와 관계를 명확히 제시함으로써 대학 교육과정 개발 및 운영을 위한 실질적 시사점을 제공하였다는 데 의의가 있다.N
Incipient plasticity of potassium-doped tungsten under nanoindentation: A comparison between experiments and defect dynamics simulations
No full textThe effects of potassium (K) doping on the incipient plasticity of tungsten (W) under nanoindentation were investigated using a combination of experiments and mesoscale defects dynamic simulations. The transmission electron microscopy study reveal that nanometer-sized bubbles were formed through the vaporization of K in specimens prepared by spark plasma sintering. In order to investigate the mechanical properties of the K-doped W specimens, nano-characterization experiments and defect dynamics simulations were conducted, comparing with those in pure W. Nanoindentation tests reveal that the maximum shear yield stress approaches the theoretical strength in annealed pure W, while K-doped W samples exhibit significant yield drop accompanied with stochastic variations. A newly developed mesoscale defect dynamics model to concurrently couple dislocation dynamics with finite element method has been also employed to investigate micro-mechanisms of plasticity under nanoindentation and the effects of K-bubbles on the plastic deformation. The simulations revealed that the localized stress concentration induced by the K-bubbles promoted dislocation nucleation and enhanced plastic deformation, thereby reducing the yield stress, showing good agreement with the experiment.N
Direct TiH2 powder production by the reduction of TiO2 using Mg in Ar and H2 mixed gas atmosphere
No full textTo develop a direct production process for TiH2 powder from TiO2, the reduction of TiO2 using Mg in molten MgCl2 - KCl salt under a high hydrogen chemical potential was investigated. The reduction of nano-sized TiO2 powder was conducted at 973 - 1073 K under an Ar or Ar and 10% H2 mixed gas atmosphere when the mass ratios of Mg to feed and salt to feed were 1.14 - 2.86 and 0.87 - 3.48, respectively. The results showed that the oxygen concentration in the Ti product decreased as the mass ratio of salt to feed and temperature decreased. Furthermore, according to the variation in Mg amounts, the oxygen concentration was 0.350 - 0.441 mass%. In addition, employing hydrogen during the reduction enhances the capability to decrease the oxygen concentration in the Ti product. Moreover, the hydrogen concentration in the Ti product increased as the amount of molten salt decreased, thereby enabling pure TiH2 production. As a result, TiH2 powder with an oxygen concentration of 0.350 mass% was obtained under a certain condition. These results demonstrate the feasibility of the direct production of low-oxygen TiH2 powder from TiO2 via reduction at 973 K using Mg in an Ar and H2 mixed gas atmosphere.Y