Daegu Gyeongbuk Institute of Science and Technology
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Ecologism with a Human Face: A critical approach to Park Nohae’s 1990s poetry
No full text1990년대 후반 박노해 시와 사유, 활동의 변화에 대한 탐구는 그러한 변화에 작용하는 하나의 기원이자 배경으로 1970년대 민중론, 좀 더 좁혀서 민중신학적 사상과의 연관성에 주목할 것을 요청한다. 노동현장에 들어가 혁명가로 거듭나기 전의 박노해는 1970년대 사회 각 분야의 민중운동과 함께 형성 및 전개되며 흐름을 같이 하고 있었던 기독교 사회운동 및 민중신학과 조우했다. 박해받는 민중의 해방에 대한 민중신학적 사유와 실천이 ‘박노해’의 ‘박해받는 노동자 해방’이라는 상징의 한 기원이었다. 한편 이른바 ‘사상 전향’ 이후인 1990년대 후반 박노해의 시에서 생태주의와 종교적 영성을 앞세우기 시작한 변화는 1970년대적인 민중을 재전유한 생활민중과 그들의 생태주의적 나눔의 삶을 발견하면서 비롯된다. 그러나 그의 시는 생활민중의 생태주의적 삶과 자연과의 관계를 충분히 구체적으로 담아내지 못하고, 미학적 시도나 사상적 탐구 또한 본격적으로 전개되지 못한다. 그의 시가 다만 추상적이고 포괄적인 사람, ‘나 개인’, 지구에 사는 모든 생명체와 이어진 전체론적 인류만을 상정하는 데 그치는 것은, 사람들 개개인의 권리와 책임에 대한 의식에서 나아가 그것들에 정초한 공통의 집단적 행위로 조직화된 공적 세계로서의 사회 구조에 대한 인식과 상상력, 비전을 잃었기 때문이다. 그 결과 그의 생태주의적 시와 사유는 구체적인 실천가능성을 누락한 생태적 낭만주의로 경사된다.FALSEkc
Enhanced Biomass Productivity of Freshwater microalga, Parachlorella kessleri for Fixation of Atmospheric CO2 Using Optimal Culture Conditions
No full textThis study attempted to improve the growth of the freshwater microalgae, Parachlorella kessleri, through the sequential optimization of culture conditions. This attempt aimed to enhance the microalgae's ability to fixate atmospheric CO2. Culture temperature and light intensity appropriate for microalgal growth were scanned using a high-throughput photobioreactor system. The supplied air flow rate varied from 0.05 to 0.3 vvm, and its effect on the growth rate of P. kessleri was determined. Next, sodium phosphate buffer was added to the culture medium (BG11) to enhance CO2 fixation by increasing the availability of CO2(HCO3-) in the culture medium. The results indicated that optimal culture temperature and light intensity were 20°C-25°C and 300 μE/m2/s, respectively. Growth rates of P. kessleri under various air flow rates highly depended on the increase of the culture's flow rate and pH which determines CO2 availability. Adding sodium phosphate buffer to BG11 to maintain a constant neutral pH (7.0) improved microalgal growth compared to control conditions (BG11 without sodium phosphate). These results indicate that the CO2 fixation rate in the air could be enhanced via the sequential optimization of microalgal culture conditions.FALSEkc
FeO4-Type Active Sites Grown on Fe-Doped Ni Core Surfaces during the Initial Oxygen Evolution Reactions: Fe-Doping Effect?
No full textClean hydrogen production by water splitting is hampered by sluggish oxygen evolution reactions (OER). The most promising high-activity, high-stability, and low-cost OER catalyst working in alkaline conditions is a core-shell nanostructure whose Fe-doped Ni (NiFe) core particles are encapsulated by N-doped graphitic (NC) shells. However, hidden beneath the irregular NC shells, the active site in the core as well as the origin of the favorable Fe-doping effect has not been well identified. We thus herein use density functional theory calculations and derive an active site model on the core by mimicking the oxidation of the NiFe metal surface during the initial OER cycles required for catalyst activation. During these cycles at pH 14, an oxophilic Fe atom protrudes out of the O-covered surface and sits on Ni oxide layers grown on top of the core surface, forming an FeO4-type structure that requires very low overpotentials for subsequent OER cycles. An equivalent NiO4-type structure, if it forms, may require even lower overpotentials, but the protrusion of less oxophilic Ni into surrounding O atoms needs to overcome a much higher free energy barrier. Indeed, the FeO4-type structure has been suggested as an active site whose facile dissolution as Fe(OH)4- explains for the activity loss of catalysts directly exposed to the electrolyte. © 2024 American Chemical Society.FALSEsciescopu
Geometrical Parameters Investigation of a Zig-Zag Soft Pneumatic Actuators
No full textUnlike conventional rigid robots, soft robots utilize soft materials that allow them to deform based on their structure, enabling safe interaction with humans. Among various pneumatic actuators in soft robotics, pneumatic network (PneuNet) actuators, which consist of bellows-like chambers, enable bending and repetitive actions with minimal material deformation at low pressures. Given that the performance of PneuNet actuators is affected by their geometric parameters, considering the impact of geometric variations is crucial in this field. Herein, the effect of geometrical parameters on a zig-zag soft pneumatic actuator, and an improved version of conventional PneuNet actuators designed for enhanced performance are investigated. Finite element analysis (FEA) indicates that smaller gaps between chambers, thinner bottom layers, and taller chamber heights result in greater bending under the same pressure within the tested parameter range. Experimental results reveal a 30.9% larger bending angle than that of conventional actuators with the same parameters. The FEA results are consistent with the experimental data, exhibiting an error of 10.2%. Furthermore, the tip and grip forces are 1.45 times and 1.3 times larger, respectively, compared to conventional actuators. These results provide direction for the design of zig-zag soft pneumatic actuators, showcasing improved performance over conventional soft actuators. © 2024 Wiley-VCH GmbH.FALSEsciescopu
ULTRASOUND SENSOR AND CONTROLLING METHOD OF THE SAME BASED ON SILICON PHOTONIC RING RESONATOR AND CANTILEVER STRUCTURE
No full textAnatomical topology of extrahippocampal projections from dorsoventral CA pyramidal neurons in mice
No full textThe hippocampus primarily functions through a canonical trisynaptic circuit, comprised of dentate granule cells and CA1-CA3 pyramidal neurons (PNs), which exhibit significant heterogeneity along the dorsoventral axis. Among these, CA PNs are known to project beyond the hippocampus into various limbic areas, critically influencing cognitive and affective behaviors. Despite accumulating evidence of these extrahippocampal projections, the specific topological patterns—particularly variations among CA PN types and between their dorsal and ventral subpopulations within each type—remain to be fully elucidated. In this study, we utilized cell type-specific Cre mice injected with fluorescent protein-expressing AAVs to label each CA PN type distinctly. This method further enabled the dual-fluorescence labeling of dorsal and ventral subpopulations using EGFP and tdTomato, respectively, allowing a comprehensive comparison of their axonal projections in an animal. Our findings demonstrate that CA1 PNs predominantly form unilateral projections to the frontal cortex (PFC), amygdala (Amy), nucleus accumbens (NAc), and lateral septum (LS), unlike CA2 and CA3 PNs making bilateral innervation to the LS only. Moreover, the innervation patterns especially within LS subfields differ according to the CA PN type and their location along the dorsoventral axis of the hippocampus. This detailed topographical mapping provides the neuroanatomical basis of the underlying functional distinctions among CA PN types. Copyright © 2024 Lee, Park, Jeong, Oh, Yoon and Oh.TRUEsciescopu
Hollow PtCo alloy nanostructures for efficient oxygen reduction electrocatalysis in polymer electrolyte membrane fuel cells
No full textAchieving an efficient oxygen reduction reaction (ORR) is of prime importance for fuel cell commercialization. Herein, a hollow nanostructure of PtCo alloy with an average particle size of only ∼5 nm was prepared through a simplistic ambient oxygen-involved surface engineering strategy. The electrochemical evaluation of the catalyst confirmed an initial mass activity (MA) of 0.56 and 0.48 A mgPt−1 at 0.9 V based on the rotating disk electrode and membrane electrode assembly test, respectively, thus successfully breaking the previous perceptions of a very huge gap between the half- and full-cell MA. After 30 000 cycles of the accelerated stress test, the catalyst demonstrated durable cathodic reaction in fuel cells, satisfying the stability standards of the US Department of Energy. We discovered that efficient ORR electrocatalysis originates from optimized surface strain and favorable coordination environments of the designed catalyst. © 2024 The Royal Society of Chemistry.FALSEsciescopu
A promising high temperature 2D thermoelectric material: novel single-layer ZrHfS4
No full textBased on the first-principles calculation and Boltzmann transport theory, we report the discovery of a promising candidate for high-performance two-dimensional (2D) thermoelectric material: the single-layer (1L) ZrHfS4. Through the first-principles molecular dynamics simulation and phonon calculation, 1L-ZrHfS4 is predicted to be thermodynamically stable even at high temperatures. In addition, the lattice thermal conductivity of 1L-ZrHfS4 is calculated to be 10.2 W m−1 K−1, which is smaller than that of 2D transition-metal dichalcogenides, such as MoS2 and WS2. Notably, considering not only all the transport coefficients but also the relaxation time for both acoustic and optical phonon scattering, the maximum figure of merit (ZT) of 1L-ZrHfS4 at 1200 K can achieve 1.92 at moderate n-type doping. These findings suggest 1L-ZrHfS4 as a potential material for efficient thermoelectric energy conversion, particularly in applications requiring high temperature operation. © 2024 The Royal Society of Chemistry.FALSEsciescopu
A comparative study of techniques to remove stimulation artifacts during simultaneous recording and stimulation in the deep brain
No full text파킨슨병을 비롯한 다양한 뇌신경질환의 증상을 완화시키는 데 사용되는 뇌심부자극술은 부작용을 최소화하고 배터리 소모량을 개선시키기 위해 필요할 때만 자극을 수행하는 적응형 알고리즘을 사용하게 된다. 이때, 자극이 필요한 시점을 결정하기 위해서 자극과 동시에 기록한 뇌신호를 사용하여 뇌의 특성을 파악하게 되는데, 원활한 뇌신호 분석을 위해서는 자극에 의해 발생한 아티팩트를 제거하는 것이 필수적이다. 본 연구에서는 이러한 뇌심부자극술을 수행하는 과정에서 발생하는 자극 아티팩트를 제거하기 위한 방법으로 공간 또는 시간 방향의 정보를 활용하는 기법을 비교하고, 뇌신호의 특성 분석을 더 원활하게 해주는 기법을 제시한다
Time-efficient atmospheric water harvesting using Fluorophenyl oligomer incorporated MOFs
Get PDFAdsorption-based atmospheric water harvesting (AWH) has the potential to address water scarcity in arid regions. However, developing adsorbents that effectively capture water at a low relative humidity (RH < 30%) and release it with minimal energy consumption remains a challenge. Herein, we report a fluorophenyl oligomer (FO)-incorporated metal-organic framework (MOF), HKUST-1 (FO@HK), which exhibits fast adsorption kinetics at low RH levels and facile desorption by sunlight. The incorporated fluorophenyl undergoes vapor-phase polymerization at the metal center to generate fluorophenyl oligomers that enhance the hydrolytic stability of FO@HK while preserving its characteristic water sorption behavior. The FO@HK exhibited vapor sorption rates of 8.04 and 11.76 L kg-1MOF h-1 at 20 and 30% RH, respectively, which are better than the state-of-the-art AWH sorbents. Outdoor tests using a solar-driven large-scale AWH device demonstrate that the sorbent can harvest 264.8 mL of water at a rate of 2.62 L kg-1MOF per day. This study provides a ubiquitous strategy for transforming water-sensitive MOFs into AWH sorbents. © 2024. The Author(s).TRUEsciescopu