Publications by authors named "Young June Kim"

The 5d^{1} ordered double perovskites present an exotic playground for studying novel multipolar physics due to large spin-orbit coupling. We present Re L_{3} edge resonant inelastic x-ray scattering (RIXS) results that reveal the presence of the dynamic Jahn-Teller effect in the A_{2}MgReO_{6} (A=Ca, Sr, Ba) family of 5d^{1} double perovskites. The spin-orbit excitations in these materials show a strongly asymmetric line shape and exhibit substantial temperature dependence, indicating that they are dressed with lattice vibrations.

View Article and Find Full Text PDF
Article Synopsis
  • The study investigates how the Yb valence in the compound YbB4 changes with temperature, using advanced spectroscopy techniques from 12 to 300 K.
  • Findings show that the Yb valence transitions from approximately 2.61 at 12 K to 2.67 at 300 K, supporting that YbB4 behaves as a Kondo system with significant interactions.
  • The research suggests that the notable Kondo interaction might prevent YbB4 from magnetic ordering at low temperatures, and it also examines the relationship between zero-point valence and Kondo temperature scales.
View Article and Find Full Text PDF

Background: Rheumatoid arthritis (RA) is a chronic inflammatory disease of joint, but there is no known cure. 3'-sialyllactose (3'-SL) is an oligosaccharide that is abundant in breast milk of mammals, and has anti-inflammatory properties. However, the efficacy of 3'-SL on RA remains unclear.

View Article and Find Full Text PDF

We report our study of cobalt (II) titanate, CoTiO, in which magnetic Co ions are replaced by non-magnetic ions. The antiferromagnetic ordering transition of CoTiOaround 37 K is described with ferromagnetic honeycomb layers coupled antiferromagnetically along the crystallographic-direction. The effect of magnetic dilution on the Néel temperature of this material is investigated through the doping of Znand Mgin place of Cofor various dilution levels up to+= 0.

View Article and Find Full Text PDF

Ru M-edge resonant inelastic x-ray scattering (RIXS) measurements of [Formula: see text] with 27 meV resolution reveals a spin-orbit exciton without noticeable splitting. We extract values for the spin-orbit coupling constant ([Formula: see text] meV) and trigonal distortion field energy ([Formula: see text] meV) which support the [Formula: see text] nature of [Formula: see text]. We demonstrate the feasibility of M-edge RIXS for 4d systems, which allows ultra high-resolution RIXS of 4d systems until instrumentation for L-edge RIXS improves.

View Article and Find Full Text PDF

Vav1 is a Rho/Rac guanine nucleotide exchange factor primarily expressed in hematopoietic cells. In this study, we investigated the potential role of Vav1 in osteoclast (OC) differentiation by comparing the ability of bone marrow mononuclear cells (BMMCs) obtained from Vav1-deficient (Vav1-/-) and wild-type (WT) mice to differentiate into mature OCs upon stimulation with macrophage colony stimulating factor and receptor activator of nuclear kappa B ligand in vitro. Our results suggested that Vav1 deficiency promoted the differentiation of BMMCs into OCs, as indicated by the increased expression of tartrate-resistant acid phosphatase, cathepsin K, and calcitonin receptor.

View Article and Find Full Text PDF

A correlated material in the vicinity of an insulator-metal transition (IMT) exhibits rich phenomenology and a variety of interesting phases. A common avenue to induce IMTs in Mott insulators is doping, which inevitably leads to disorder. While disorder is well known to create electronic inhomogeneity, recent theoretical studies have indicated that it may play an unexpected and much more profound role in controlling the properties of Mott systems.

View Article and Find Full Text PDF

We report a resonant inelastic x-ray scattering study of the magnetic excitation spectrum in a highly insulating Eu_{2}Ir_{2}O_{7} single crystal that exhibits a metal-insulator transition at T_{MI}=111(7)  K. A propagating magnon mode with a 20 meV bandwidth and a 28 meV magnon gap is found in the excitation spectrum at 7 K, which is expected in the all-in-all-out magnetically ordered state. This magnetic excitation exhibits substantial softening as the temperature is raised towards T_{MI} and turns into a highly damped excitation in the paramagnetic phase.

View Article and Find Full Text PDF

The honeycomb Kitaev-Heisenberg model is a source of a quantum spin liquid with Majorana fermions and gauge flux excitations as fractional quasiparticles. Here we unveil the highly unusual low-temperature heat conductivity κ of α-RuCl_{3}, a prime candidate for realizing such physics: beyond a magnetic field of B_{c}≈7.5  T, κ increases by about one order of magnitude, both for in-plane as well as out-of-plane transport.

View Article and Find Full Text PDF

Background: Islet encapsulation techniques have shown limited success in maintaining islet survival and function because encapsulation decreases oxygen supply. In this study, an oxygen-generating scaffold was fabricated to prevent hypoxic cell damage and improve the viability and insulin secretion of islets.

Methods: We fabricated an oxygen-generating scaffold by mixing calcium peroxide (CaO ) with polydimethylsiloxane (PDMS).

View Article and Find Full Text PDF

We report the unique role of CX3CL1 (or fractalkine) on CD11b myelomonocytic cells expressing CX3CR1, the only known receptor for CX3CL1, in promoting blood perfusion recovery. In a mouse ischemic hind-limb model, CD11b CX3CR1 cells migrated to ischemic femoral muscles through CX3CL1-mediated chemotaxis. CD11b CX3CR1 macrophages isolated from ischemic tissues [tissue (T)-CD11b CX3CR1 ] of muscle exert a proangiogenic effect through platelet factor-4 (CXCL4; PF-4) production.

View Article and Find Full Text PDF

Persistent Müllerian duct syndrome (PMDS) is a pseudohermaphroditism in males characterized by the presence of Müllerian duct derivatives. As PMDS dogs often lack clinical symptoms, a molecular diagnosis is essential to identify the syndrome in these animals. In this study, a new molecular method using DNA mismatch-specific Surveyor nuclease was developed.

View Article and Find Full Text PDF

Background: Despite the development of α1,3-galactosyl transferase-knockout (GTKO) pigs, acute humoral xenograft rejection caused by antibodies against non-Gal antigens, along with complement activation, are hurdles that need to be overcome. Among non-Gal antigens, N-glycolylneuraminic acid (Neu5Gc) is considered to play an important role in xenograft rejection in human.

Methods: We generated human embryonic kidney 293 (HEK293) cells that expressed xenogeneic Neu5Gc (HEK293-pCMAH) or α1,3Gal (HEK293-pGT) antigen and investigated the degree of human antibody binding and complement-dependent cytotoxicity (CDC) against these antigens using 100 individual human sera.

View Article and Find Full Text PDF

Objective: Production of alpha-1,3-galactosyltransferase (GT)-deficient pigs is essential to overcome xenograft rejection in pig-to-human xenotransplantation. However, the production of such pigs requires a great deal of cost, time, and labor. Heterozygous GT knockout pigs should be bred at least for two generations to ultimately obtain homozygote progenies.

View Article and Find Full Text PDF

Tumor suppressor p53 plays a critical role in the regulation of cell cycle and apoptosis in mammals. Mutations of p53 often cause various cancers. Murine models have improved our understanding on tumorigenesis associated with p53 mutations.

View Article and Find Full Text PDF

The combination of electronic correlation and spin-orbit coupling is thought to precipitate a variety of highly unusual electronic phases in solids, including topological and quantum spin liquid states. We report a Raman scattering study that provides evidence for unconventional excitations in α-RuCl_{3}, a spin-orbit coupled Mott insulator on the honeycomb lattice. In particular, our measurements reveal unusual magnetic scattering, typified by a broad continuum.

View Article and Find Full Text PDF
Article Synopsis
  • The study investigates the relationship between structural and magnetic properties in CaFe2(As1-xPx)2 using Fe Kβ x-ray spectroscopy and theoretical calculations.
  • It reveals a puzzling temperature-dependent behavior of local moments, similar to that observed in rare earth-doped CaFe2As2, explained through a single scaling parameter that describes magnetic moments across different materials.
  • The findings highlight strong magnetoelastic coupling and thermal expansion effects that contribute to the unique magnetic behavior, showcasing the dual nature of magnetism in iron pnictides.
View Article and Find Full Text PDF

Carbohydrate antigens expressed on pig cells are considered to be major barriers in pig-to-human xenotransplantation. Even after α1,3-galactosyltransferase gene knock-out (GalT-KO) pigs are generated, potential non-Gal antigens are still existed. However, to the best of our knowledge there is no extensive study analyzing N-glycans expressed on the GalT-KO pig tissues or cells.

View Article and Find Full Text PDF

Ataxia telangiectasia (A-T) is a recessive autosomal disorder associated with pleiotropic phenotypes, including progressive cerebellar degeneration, gonad atrophy, and growth retardation. Even though A-T is known to be caused by the mutations in the Ataxia telangiectasia mutated (ATM) gene, the correlation between abnormal cellular physiology caused by ATM mutations and the multiple symptoms of A-T disease has not been clearly determined. None of the existing ATM mouse models properly reflects the extent to which neurological degeneration occurs in human.

View Article and Find Full Text PDF
Article Synopsis
  • The study investigates x-ray scattering techniques on thin films of Sr2IrO4 that are under different types of strain, showcasing the films' unique magnetic properties compared to bulk material.
  • The films exhibit anisotropic magnetic correlations, meaning the magnetic interactions vary significantly depending on the direction, with stronger correlations in-plane than out-of-plane.
  • The effects of compressive and tensile strain on the films are highlighted, as compressive strain lowers the temperature for magnetic ordering while tensile strain has the opposite effect, and these changes are linked to alterations in bond lengths.
View Article and Find Full Text PDF

Objective: Perfusion computed tomography (PCT) has the ability to measure quantitative value and produce maps of mean transit time (MTT), cerebral blood flow (CBF), and cerebral blood volume (CBV). We assessed cerebral hemodynamics by using these parameters and acetazolamide (ACZ) challenge for pre- and post-procedural evaluation in patients with unilateral cerebrovascular stenotic disease.

Methods: Thirty patients underwent pre-procedural PCT with ACZ challenge, and 24 patients (80%) was conducted follow up PCT after angioplasty with same protocol.

View Article and Find Full Text PDF
Article Synopsis
  • The study examines how nickel doping in BaFe(2-x)Ni(x)As2 affects its structural and magnetic properties, revealing a shift in phase transition temperatures with increased doping.
  • The tetragonal-to-orthorhombic structural transition (T(s)) and the antiferromagnetic transition (T(N)) become separated as doping increases, with a notable approach toward a quantum bicritical point which correlates with optimal superconductivity.
  • A secondary magnetic phase forms at certain doping levels, leading to a situation where T(N) aligns closely with the superconducting transition temperature (T(c)), suggesting an avoided quantum critical point that impacts both normal and superconducting behavior.
View Article and Find Full Text PDF
Article Synopsis
  • The study explores the electronic structure of honeycomb lattice iridates Na(2)IrO(3) and Li(2)IrO(3) using resonant inelastic x-ray scattering (RIXS), revealing detailed d-d excitations.
  • The research highlights that the crystal-field splitting of j(eff)=3/2 states is notably smaller than the typical spin-orbit energy scale, supporting the application of j(eff) physics in these materials.
  • It also notes an excitonic enhancement of the particle-hole excitation gap, suggesting significant nearest-neighbor Coulomb interactions, characterizing both compounds as spin-orbit Mott insulators similar to Sr(2)IrO(4).
View Article and Find Full Text PDF

We report an Fe Kβ x-ray emission spectroscopy study of local magnetic moments in the rare-earth doped iron pnictide Ca(1-x)RE(x)Fe(2)As(2) (RE = La, Pr, and Nd). In all samples studied the size of the Fe local moment is found to decrease significantly with temperature and goes from ∼ 0.9 μ(B) at T = 300 K to ∼ 0.

View Article and Find Full Text PDF