Publications by authors named "Taehwan Jang"

Article Synopsis
  • - Memristive neuromorphic computing offers fast and energy-efficient solutions for artificial intelligence, but faces commercialization hurdles due to reliability issues from stochastic ion movements.
  • - The study introduces a new method using fluorine doping in TiO memristors, which results in reduced device variations, faster switching speeds, and better overall performance.
  • - Atomistic simulations show that fluorine ions help stabilize the device by attracting oxygen vacancies and lowering migration barriers, leading to more reliable and efficient memristor fabrication for neuromorphic hardware.
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Article Synopsis
  • The study explores the crystal and magnetic properties of the van der Waals antiferromagnet α-RuCl using x-ray and neutron diffraction techniques, identifying its crystal structure as monoclinic (C2/m) at room temperature.
  • As the temperature decreases, a phase transition occurs, forming a rhombohedral (R3-) structure with an isotropic honeycomb lattice and three-fold rotational symmetry.
  • Below a critical temperature of around 6-6.6K, a zigzag-type antiferromagnetic order emerges, exhibiting characteristics tied to the Ising model and revealing complex magnetic behaviors influenced by Kitaev spin interactions.
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The water oxidation reaction, the most important reaction for hydrogen production and other sustainable chemistry, is efficiently catalyzed by the MnCaO cluster in biological photosystem II. However, synthetic Mn-based heterogeneous electrocatalysts exhibit inferior catalytic activity at neutral pH under mild conditions. Symmetry-broken Mn atoms and their cooperative mechanism through efficient oxidative charge accumulation in biological clusters are important lessons but synthesis strategies for heterogeneous electrocatalysts have not been successfully developed.

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An ongoing challenge in the study of quantum materials, is to reveal and explain collective quantum effects in spin systems where interactions between different modes types are important. Here we approach this problem through a combined experimental and theoretical study of interacting transverse and longitudinal modes in an easy-plane quantum magnet near a continuous quantum phase transition. Our inelastic neutron scattering measurements of BaFeSiO reveal the emergence, decay, and renormalization of a longitudinal mode throughout the Brillouin zone.

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The design of small molecules that inhibit disease-relevant proteins represents a longstanding challenge of medicinal chemistry. Here, we describe an approach for encoding this challenge-the inhibition of a human drug target-into a microbial host and using it to guide the discovery and biosynthesis of targeted, biologically active natural products. This approach identified two previously unknown terpenoid inhibitors of protein tyrosine phosphatase 1B (PTP1B), an elusive therapeutic target for the treatment of diabetes and cancer.

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Environments experienced during development have long-lasting consequences for adult performance and fitness. The "environmental matching" hypothesis predicts that individuals perform best when adult and developmental environments match whereas the "silver spoon" hypothesis expects that fitness is higher in individuals developed under favorable environments regardless of adult environments. Temperature and nutrition are the two most influential determinants of environmental quality, but it remains to be elucidated which of these hypotheses better explains the long-term effects of thermal and nutritional histories on adult fitness traits.

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Temperature and nutrition are amongst the most influential environmental determinants of Darwinian fitness in ectotherms. Since the ongoing climate warming is known to alter nutritional environments encountered by ectotherms, a precise understanding of the integrated effects of these two factors on ectotherm performance is essential for improving the accuracy of predictions regarding how ectotherms will respond to climate warming. Here we employed response surface methodology to examine how multiple life-history traits were expressed across a grid of environmental conditions representing full combinations of six ambient temperatures (13, 18, 23, 28, 31, 33 °C) and eight dietary protein:carbohydrate ratios (P:C = 1:16, 1:8, 1:4, 1:2, 1:1, 2:1, 4:1, 8:1) in Drosophila melanogaster.

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We propose a novel origin of magnetic anisotropy to explain the unusual magnetic behaviors of layered ferromagnetic Cr compounds (3d^{3}) wherein the anisotropy field varies from ≲0.01 to ∼3  T on changing the ligand atom in a common hexagonal structure. The effect of the ligand p orbital spin-orbit (LS) coupling on the magnetic anisotropy is explored by using four-site full multiplet cluster model calculations for energies involving the superexchange interaction at different spin axes.

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Protein and carbohydrate are the two major macronutrients that exert profound influences over fitness in many organisms, including Our understanding of how these macronutrients shape the components of fitness in has been greatly enhanced by the use of nutritional geometry, but most nutritional geometric analyses on this species have been conducted using semi-synthetic diets that are not chemically well defined. Here, we combined the use of nutritional geometry and chemically defined diets to compare the patterns of larval and adult life-history traits expressed across 34 diets systematically varying in protein:carbohydrate (P:C) ratio and in protein plus carbohydrate (P+C) concentration. The shape of the response surfaces constructed for all larval and adult traits differed significantly from one another, with the nutritional optima being identified at P:C 1:4 for lifespan (P+C 120 g l), 1:2 for egg-to-adult viability (120 g l), 1:1 for female body mass at adult eclosion (240 g l) and lifetime fecundity (360 g l), 2:1 for larval developmental rate (60 g l) and 8:1 for egg production rate (120 g l).

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Temperature can modulate the responses of ectotherms to environmental stressors, such as food shortage. Temperature-mediated plasticity in starvation resistance can arise by changes in the amount of energy stored, the speed of energy expenditure, or the threshold energy reserves required for survival. However, few studies have investigated how temperature affects these physiological mechanisms underlying starvation resistance.

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Most ectotherms mature at a larger body size in colder conditions, a phenomenon known as the temperature-size rule. While a number of hypotheses have been proposed to explain this rule, little work has been done to understand it from a nutritional perspective. We have used the final-instar caterpillars of Spodoptera litura to investigate how dietary protein∶carbohydrate (P∶C) balance influences the relationship between temperature and body size.

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Multiple genetic and environmental factors interact to influence starvation resistance, which is an important determinant of fitness in many organisms, including Drosophila melanogaster. Recent studies have revealed that mating can alter starvation resistance in female D. melanogaster, but little is known about the behavioral and physiological mechanisms underlying such mating-mediated changes in starvation resistance.

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Hybridization between conduction electrons and the strongly interacting f-electrons in rare earth or actinide compounds may result in new states of matter. Depending on the exact location of the concomitant hybridization gap with respect to the Fermi energy, a heavy fermion or an insulating ground state ensues. To study this entanglement locally, we conducted scanning tunneling microscopy and spectroscopy (STS) measurements on the "Kondo insulator" SmB6.

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