174 results match your criteria: "Seoul National University (SNU))[Affiliation]"

The primate putamen processes cognitive flexibility alongside the caudate and ventral striatum with similar speeds of updating values.

Prog Neurobiol

December 2024

School of Biological Sciences, Seoul National University (SNU), Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea. Electronic address:

The putamen is thought to generate habitual actions by processing value information relayed from the ventral striatum through the caudate nucleus. However, it is a question what value the putamen neurons process and whether the putamen receives serially processed value through the striatal structures. We found that neurons in the primate putamen, caudate, and ventral striatum selectively encoded flexibly updated values for adaptive behaviors with similar learning speeds, rather than stably sustained values for habit.

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Animals can discriminate diverse sensory values with a limited number of neurons, raising questions about how the brain utilizes neural resources to efficiently process multi-dimensional inputs for decision-making. Here, we demonstrate that this efficiency is achieved by reducing sensory dimensions and converging towards the value dimension essential for goal-directed behavior in the putamen. Humans and monkeys performed tactile and visual value discrimination tasks while their neural responses were examined.

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Ammonia is a chemical compound in considerable global demand and plays a crucial role as an environmentally friendly energy carrier for hydrogen energy storage. The electrochemical nitrogen reduction reaction (eNRR) using copper sulfide catalysts is being extensively studied as an environmentally sustainable approach to the energy-intensive Haber-Bosch process for ammonia production. In this study, we aimed to prepare CuS hollow spheres modified with Au nanoparticles using an antisolvent crystallization-based method to be used as the catalysts for eNRR.

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Selective Control of Electric Charge of Weyl Fermions in Pyrochlore Iridates.

Adv Mater

December 2024

State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, 100084, China.

Weyl fermions can exhibit exotic phenomena due to their magnetic charge in momentum space, while Weyl nodes are usually located away from Fermi energy, which forms electron or hole pockets as the electric charges. Previous studies have mostly focused on the magnetic charge, however, the electric charges are rarely explored. Here, the intriguing Hall responses arising from the interplay between magnetic and electric charges of Weyl fermions in pyrochlore iridates are reported.

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Article Synopsis
  • A study tested a mobile app designed to help patients eat the right amount of calories and protein after they had surgery for stomach cancer.
  • 39 patients used the app to track what they ate and learned how easy and helpful it was.
  • Results showed that patients who were underweight did a great job using the app and reaching their nutrition goals, suggesting that digital tools can really help people recover after such surgeries.
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Is Low Polydispersity Always Beneficial? Exploring the Impact of Size Polydispersity on the Microstructure and Rheological Properties of Graphene Oxide.

ACS Appl Mater Interfaces

October 2024

School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University (SNU), Seoul 08826, Republic of Korea.

Article Synopsis
  • Graphene oxide (GO) is a valuable material in advanced engineering applications like soft robotics and flexible devices, requiring an understanding of its properties in solution.
  • GO's polydispersity—variability in particle size—affects its mechanical behavior and flowability, but research on this topic is limited.
  • This study explores how GO's polydispersity influences its rheological properties and yielding behavior, using techniques like rheometry and microscopy, finding that higher polydispersity improves these characteristics, which is useful for applications like 3D printing.
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Unveiling Direct Electrochemical Oxidation of Methane at the Ceria/Gas Interface.

Adv Mater

November 2024

Department of Materials Science and Engineering Research Institute of Advanced Materials, Seoul National University (SNU), Seoul, 08826, Republic of Korea.

Article Synopsis
  • Solid oxide fuel cells (SOFCs) efficiently use hydrocarbon fuels, especially from carbon-neutral sources, with ceria-based oxides playing a key role in handling hydrocarbon activation and carbon coking.
  • The mechanisms behind methane oxidation at the ceria/gas interface are not fully understood, partly due to the complexity of metal/oxide composite electrodes and related reactions.
  • This study reveals that ceria surfaces can cleave C─H bonds and that hydroxyl (HO) formation is crucial for the reaction rate, providing new insights for optimizing electrode designs in SOFCs.
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Complex coacervation plays an important role in various fields. Here, the influences of the backbone chemistry and ionic functional groups of five pairs of oppositely charged polyelectrolytes on complex coacervation were investigated. These pairs include synthetic polymers with aliphatic hydrocarbon backbones, peptides with amide bonds, and carbohydrates with glycosidic linkages.

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The activity and durability of chemical/electrochemical catalysts are significantly influenced by their surface environments, highlighting the importance of thoroughly examining the catalyst surface. Here, Cu-substituted LaSrCoFeO is selected, a state-of-the-art material for oxygen reduction reaction (ORR), to explore the real-time evolution of surface morphology and chemistry under a reducing atmosphere at elevated temperatures. Remarkably, in a pioneering observation, it is discovered that the perovskite surface starts to amorphize at an unusually low temperature of approximately 100 °C and multicomponent metal nanocatalysts additionally form on the amorphous surface as the temperature raises to 400 °C.

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Dual-Layer Nanoengineered Urinary Catheters for Enhanced Antimicrobial Efficacy and Reduced Cytotoxicity.

Adv Healthc Mater

December 2024

Biomedical Engineering Research Center, Asan Institute for Life Sciences, Asan Medical Center, 88 Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, Republic of Korea.

Catheter-associated urinary tract infection (CAUTI) is the most common healthcare-associated infection; however, current therapeutic strategies remain insufficient for standard clinical application. A novel urinary catheter featuring a dual-layer nanoengineering approach using zinc (Zn) and silver nanoparticles (AgNPs) is successfully fabricated. This design targets microbial resistance, minimizes cytotoxicity, and maintains long-term efficacy.

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A simplified and stepwise synthetic method for producing sterically congested unsymmetrical 1,2-dicarbonyl radicals was successfully demonstrated including detailed characterization of each radical cation. Using this approach, an aryl- and N-heterocyclic carbene-substituted 1,2-dicarbonyl radical in its neutral form is generated, revealing the stabilizing role of N-heterocyclic carbenes.

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Demands for green ammonia production increase due to its application as a proton carrier, and recent achievements in electrochemical Li-mediated nitrogen reduction reactions (Li-NRRs) show promising reliability. Here, it is demonstrated that F-containing additives in the electrolyte improve ammonia production by modulating the solid electrolyte interphase (SEI). It is suggested that the anionic additives with low lowest unoccupied molecular orbital levels enhance efficiency by contributing to the formation of a conductive SEI incorporated with LiF.

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Optimizing the Synergistic Effect of Co and Fe for Efficient and Durable Oxygen Evolution under Alkaline Conditions.

ACS Appl Mater Interfaces

July 2024

School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University (SNU), Seoul 08826, Republic of Korea.

Developing robust oxygen evolution reaction (OER) electrocatalysts is crucial for advancing anion exchange membrane water electrolysis (AEMWE). In this study, we present a catalyst optimizing the synergistic effect of Co and Fe by creating a CoFe-based layer on a Fe-based electrode (Fe@CoFe). The Fe@CoFe exhibits an overpotential of 168 mV at 10 mA cm under half-cell conditions and a current density of 10 A cm at 2 V in the AEMWE system with 1 M KOH.

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The electrochemical hydrogenation (ECH) of furfural (FF) offers a promising pathway for the production of furfuryl alcohol (FA) while aligning with sustainability and environmental considerations. However, this technology has primarily been studied in half-cell configurations operating at high cell voltages and low current densities. Herein, we employ a membrane electrode assembly (MEA) system with an anion-exchange membrane for the ECH of FF and systematically investigate various parameters, including the ionomer content in the cathode catalyst, electrolyte type, electrolyte concentration, and flow rate.

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Enhanced stability of boron modified NiFe hydroxide for oxygen evolution reaction.

Nanoscale

June 2024

Department of Chemistry, College of Natural Sciences, Seoul National University (SNU), Seoul 08826, Republic of Korea.

The introduction of non-metal elements including boron has been identified as a significant means to enhance oxygen evolution reaction (OER) performance in NiFe-based catalysts. To understand the catalytic activity and stability, recent attention has widened toward the Fe species as a potential contributor, prompting exploration from various perspectives. Here, boron incorporation in NiFe hydroxide achieves significantly enhanced activity and stability compared to the boron-free NiFe hydroxide.

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A new type of 0-dimensional carbon-based materials called graphene quantum dots (GQDs) is gaining significant attention as a non-toxic and eco-friendly nanomaterial. GQDs are nanomaterials composed of sphybridized carbon domains and functional groups, with their lateral size less than 10 nm. The unique and exceptional physical, chemical, and optical properties arising from the combination of graphene structure and quantum confinement effect due to their nano-size make GQDs more intriguing than other nanomaterials.

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Platinum ditelluride (1-PtTe) is a two-dimensional (2D) topological semimetal with a distinctive band structure and flexibility of van der Waals integration as a promising candidate for future electronics and spintronics. Although the synthesis of large-scale, uniform, and highly crystalline films of 2D semimetals system is a prerequisite for device application, the synthetic methods meeting these criteria are still lacking. Here, we introduce an approach to synthesize highly oriented 2D topological semimetal PtTe using a thermally assisted conversion called tellurization, which is a cost-efficient method compared to the other epitaxial deposition methods.

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Purpose: This research seeks to extend previous research into student discipline and competitiveness, at the macro or national level, to the micro or individual level. The role of factors with the potential to impact individual competitiveness, namely the expectations of the mother and the father, the importance of school discipline played in primary and secondary schools, and past participation in sport and music were examined.

Design/methodology/approach: Data from a sample of current university students and recent graduates representing Western (the United States) and Asian regions (South Korea and China) were analysed using multiple regressions to establish the explanatory power of independent variables in the competitiveness model, including testing for moderation effects of country of birth.

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To improve the initiation and speed of intended action, one of the crucial mechanisms is suppressing unwanted movements that interfere with goal-directed behavior, which is observed relatively aberrant in Parkinson's disease patients. Recent research has highlighted that dopamine deficits in Parkinson's disease predominantly occur in the caudal lateral part of the substantia nigra pars compacta (SNc) in human patients. We previously found two parallel circuits within the basal ganglia, primarily divided into circuits mediated by the rostral medial part and caudal lateral part of the SNc dopamine neurons.

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Mn-doped Sequentially Electrodeposited Co-based Oxygen Evolution Catalyst for Efficient Anion Exchange Membrane Water Electrolysis.

ACS Appl Mater Interfaces

April 2024

School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University (SNU), Seoul 08826, Republic of Korea.

Designing high-performance and durable oxygen evolution reaction (OER) catalysts is important for green hydrogen production through anion exchange membrane water electrolysis (AEMWE). Herein, a series of Mn-doped Co-based OER catalysts supported on FeOH (FCM) are presented to enhance the OER activity. Mn doping effectively reduces the size of the Co oxide particles, thereby augmenting the active surface area.

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Selective retrieval of context-relevant memories is critical for animal survival. A behavioral index that captures its dynamic nature in real time is necessary to investigate this retrieval process. Here, we found a bias in eye gaze towards the locations previously associated with individual objects during retrieval.

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Transmembrane proteins known as hyperpolarization-activated cyclic nucleotide-gated (HCN) channels control the movement of Na and K ions across cellular membranes. HCN channels are known to be involved in crucial physiological functions in regulating neuronal excitability and rhythmicity, and pacemaker activity in the heart. Although HCN channels have been relatively well investigated in the brain, their distribution and function in the retina have received less attention, remaining their physiological roles to be comprehensively understood.

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Article Synopsis
  • The advanced patterning process is essential for creating next-gen high-speed, low-power devices, with area-selective atomic layer deposition (AS-ALD) being a promising method, though it faces challenges in resolution and selectivity.
  • This study presents a new technique called superlattice-based AS-ALD (SAS-ALD) that uses a 2D MoS-MoSe superlattice template, achieving a minimum half pitch size of sub-10 nm by controlling chemical vapor deposition (CVD) precursors.
  • SAS-ALD improves selectivity through unique adsorption and diffusion processes of precursors, allowing for effective selective deposition of various materials like AlO, HfO, Ru, Te,
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