Biomedical subjects

Jaemin Kim

Publications and source records attributed to Jaemin Kim.

4 recordsLinked to original sources

PubMed2026

Integration of methylome and transcriptome reveals age-associated signatures of stage-specific dynamics and regulatory remodeling in dogs.

Aging in mammals is characterized by widespread yet coordinated epigenetic alterations. However, integrative analyses of DNA methylation and gene expression in dogs remain largely unexplored, particularly within genetically homogeneous single-breed populations. To elucidate the molecular signatures of canine aging, we profiled the genome-wide methylome and transcriptome of clinically healthy beagle dogs representing three distinct age groups. Global methylation levels were highly conserved across individuals, yet both methylation and gene expression variability increased progressively with aging. This epigenetic drift was not stochastic but structured by genomic context, as reduced CpG-gene associations indicated a gradual loss of epigenetic control over transcription. We further observed stage-related methylation change patterns across the three age groups, including early-shift, late-shift, and progressive patterns. These groups showed partially overlapping but distinct hallmark associations, suggesting links to different age-related biological processes. Together, these findings indicate that canine epigenetic aging involves multifaceted molecular changes across adulthood and support dogs as a useful model for investigating conserved molecular signatures of aging.

Beagle dog↗

PubMed2006

Synthesis of FePt nanocubes and their oriented self-assembly.

Monodisperse FePt nanocubes are synthesized at 205 degrees C by controlling decomposition of Fe(CO)5 and reduction of Pt(acac)2 and addition sequence of oleic acid and oleylamine. Different from the assembly of the sphere-like FePt nanoparticles, which shows 3D random structure orientation, self-assembly of the FePt nanocubes leads to a superlattice array with each FePt cube exhibiting (100) texture. Thermal annealing converts the chemically disordered fcc FePt to chemically ordered fct FePt, and the annealed assembly shows a strong (001) texture in the directions both parallel and perpendicular to the substrate. This shape-controlled synthesis and self-assembly offers a promising approach to fabrication of magnetically aligned FePt nanocrystal arrays for high density information storage and high performance permanent magnet applications.

Journal Article↗

PubMed2006

Electro-oxidation of formic acid catalyzed by FePt nanoparticles.

The electrocatalytic oxidation of formic acid at a gold electrode functionalized with FePt nanoparticles was studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in a mixed solution of 0.1 M HCOOH and 0.1 M HClO4. The FePt bimetallic nanoparticles, with a mean diameter of 3 nm, were prepared by a chemical reduction method. The Au/FePt nanostructured electrode was prepared firstly by the deposition of FePt nanoparticles onto a clean Au electrode surface, followed by ultraviolet ozone treatment to remove the organic coating. In CV measurements, two well-defined anodic peaks were observed at +0.20 and +0.51 V (vs. a Ag/AgCl quasi-reference). The anodic peak at +0.20 V was attributed to the oxidation of HCOOH to CO2 on surface unblocked by CO, whereas the peak at +0.51 V was ascribed to the oxidation of surface-adsorbed CO (an intermediate product of HCOOH oxidation) and further oxidation of bulk HCOOH. From the onset potential and current density of the electro-oxidation of HCOOH, FePt nanoparticles exhibit excellent electrocatalytic activities as compared to Pt and other metal alloys. EIS measurements were carried out to further examine the reaction kinetics involved in the HCOOH electro-oxidation. The EIS responses were found to be strongly dependent on electrode potentials. At potentials more positive than -0.25 V (vs. Ag/AgCl), pseudo-inductive behavior was typically observed. At potentials between +0.3 and +0.5 V, the impedance response was found to reverse from the first quadrant to the second quadrant; such negative Faradaic impedance was indicative of the presence of an inductive component due to the oxidation of surface-adsorbed CO. The impedance responses returned to normal behavior at more positive potentials (+0.6 to +0.9 V). The mechanistic variation was attributed to the formation of different intermediates (CO or oxygen containing species) on the electrode surface in different potential regions. Two equivalent circuits were proposed to model these impedance behaviors.

Catalysis↗

PubMed2004

An efficient molecular dynamics simulation method for calculating the diffusion-influenced reaction rates.

We present a molecular dynamics (MD) simulation method for calculating the diffusion-influenced reaction rates in the limit of low reactant concentrations. To calculate the reaction rate coefficient, we use MD trajectories of a nonreactive equilibrium system that are initiated with a pair of reactant molecules in reactive configuration. Hence reaction systems involving complicated reactant molecules with geometrically restricted reactivities can be treated with comparable efficiency as the simple hard-sphere reaction system. Compared to the similar MD method proposed by Van Beijeren, Dong, and Bocquet [J. Chem. Phys. 114, 6265 (2001)], the present method has a couple of advantages. First, reactions involving more general sink functions can be treated. Second, more accurate results can be obtained when the reaction probability upon collision is less than unity. As an application, we investigate the effects of nondiffusive dynamics and hydrodynamic interaction of reactants on the reaction rate.

Journal Article↗