Publications by authors named "Hyeonwoo Lee"

As proximity-aware services among devices such as sensors, IoT devices, and user equipment are expected to facilitate a wide range of new applications in the beyond 5G and 6G era, managing heterogeneous environments with diverse node capabilities becomes essential. This paper analytically models and characterizes the performance of heterogeneous random access-based wireless mutual broadcast (RA-WMB) with distinct transmit (Tx) power levels, leveraging a marked Poisson point process to account for nodes' various Tx power. In particular, this study enables the performance of RA-WMB with heterogeneous Tx power to be represented in terms of the performance of RA-WMB with a common Tx power by deriving an equivalent Tx power based on the probability distribution of heterogeneous Tx power and the path loss exponent.

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With the increasing demand for data exchange between nearby devices in proximity-based services, enhancing the security of wireless mutual broadcast (WMB) networks is crucial. However, WMB networks are inherently vulnerable to eavesdropping due to the open broadcast nature of their communication. This paper investigates the improvement of secrecy performance in random-access-based WMB (RA-WMB) networks by integrating physical layer security (PLS) techniques with hybrid duplex (HBD) operations under a stochastic geometry framework.

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A simple spontaneous deposition kit for Po determination using alpha spectrometry was newly designed, and polonium deposition characteristics under various physicochemical conditions were evaluated using it. The high-purity silver disc (99.99%) showed high deposition efficiencies of over 85.

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Background: Delphinidin (DP), an anthocyanidin found in blueberries, has antioxidant and anti-inflammatory effects. This study aimed to investigate the efficacy of DP as a storage medium for avulsed teeth.

Methods: Human periodontal ligament cells were cultured and exposed to DP solution (10, 50, and 100 μM), Dulbecco's modified Eagle's medium, Hank's balanced salt solution and tap water.

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Dental caries is a common disease that not only destroys the rigid structure of the teeth but also causes pulp necrosis in severe cases. Once pulp necrosis has occurred, the most common treatment is to remove the damaged pulp tissue, leading to a loss of tooth vitality and increased tooth fragility. Dental pulp stem cells (DPSCs) isolated from pulp tissue exhibit mesenchymal stem cell-like characteristics and are considered ideal candidates for regenerating damaged dental pulp tissue owing to their multipotency, high proliferation rate, and viability after cryopreservation.

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From mechanical syringes to electric field-assisted injection devices, precise control of liquid droplet generation has been sought after, and the present state-of-the-art technologies have provided droplets ranging from nanoliter to subpicoliter volume sizes. In this study, we present a new laser-driven method to generate liquid droplets with a zeptoliter volume, breaking the fundamental limits of previous studies. We guided an infrared laser beam through a hollow optical fiber (HOF) with a ring core whose end facet was coated with single-walled carbon nanotubes.

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Article Synopsis
  • Researchers have developed a new type of polymer micelles called copper(II) arsenite-integrated polymer micelles (CuAS-PMs) that can generate reactive oxygen species (ROS) to target cancer cells.
  • These micelles are made using a unique method that allows them to be stable in serum while releasing toxic components under specific conditions in cancer cells.
  • Animal studies show that CuAS-PMs effectively reduce tumor growth without causing harmful side effects, suggesting they could lead to new treatments that increase oxidative stress in cancerous tissues.
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Since daily drinking water is one of the major source for the ingestion of radiotoxic Rn and Ra, the demand for a simple method to determine these two radionuclides has significantly increased. In the present study, a rapid, simple sequential analysis method for determining Rn and Ra in drinking water using a liquid scintillation counter was developed. The method employs solvent extraction and correction equations for the effect of native Rn for Ra analysis.

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We report a new method to optically manipulate a single dielectric particle along closed-loop polygonal trajectories by crossing a suite of all-fiber Bessel-like beams within a single water droplet. Exploiting optical radiation pressure, this method demonstrates the circulation of a single polystyrene bead in both a triangular and a rectangle geometry enabling the trapped particle to undergo multiple circulations successfully. The crossing of the Bessel-like beams creates polygonal corners where the trapped particles successfully make abrupt turns with acute angles, which is a novel capability in microfluidics.

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Although some cell types may be defined anatomically or by physiological function, a rigorous definition of cell state remains elusive. Here, we develop a quantitative, imaging-based platform for the systematic and automated classification of subcellular organization in single cells. We use this platform to quantify subcellular organization and gene expression in >30,000 individual human induced pluripotent stem cell-derived cardiomyocytes, producing a publicly available dataset that describes the population distributions of local and global sarcomere organization, mRNA abundance, and correlations between these traits.

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CD137, a member of the TNFR family, is a costimulatory receptor, and CD137L, a member of the TNF family, is its ligand. Studies using CD137- and CD137L-deficient mice and antibodies against CD137 and CD137L have revealed the diverse and paradoxical effects of these two proteins in various cancers, autoimmunity, infections, and inflammation. Both their cellular diversity and their spatiotemporal expression patterns indicate that they mediate complex immune responses.

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In contrast to current efforts to quantify the radiation pressure of light using nano-micromechanical resonators in cryogenic conditions, we proposed and experimentally demonstrated the radiation pressure measurement in ambient conditions by utilizing a macroscopic mechanical longitudinal oscillator with an effective mass of the order of 20 g. The light pressure on a mirror attached to the oscillator was recorded in a Michelson interferometer and results showed, within the experimental accuracy of 3.9%, a good agreement with the harmonic oscillator model without free parameters.

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The antitumor capabilities of agonistic anti-4-1BB mAbs have made them an attractive target for tumor immunotherapy. However, the adverse side effects associated with agonist antibodies have hindered their clinical development. Here, we aimed to study the immune-related adverse events of repeated doses and long-term use of agonistic anti-4-1BB mAbs.

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Organic light-emitting diodes (OLEDs) are established as a mainstream light source for display applications and can now be found in a plethora of consumer electronic devices used daily. This success can be attributed to the rich luminescent properties of organic materials, but efficiency enhancement made over the last few decades has also played a significant role in making OLEDs a practically viable technology. This report summarizes the efforts made so far to improve the external quantum efficiency (EQE) of OLEDs and discusses what should further be done to push toward the ultimate efficiency that can be offered by OLEDs.

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Pulse oximetry sensors have been playing a key role as devices to monitor elemental yet critical human health states. Conventional pulse oximetry sensors, however, have relatively large power consumption, impeding their use as stand-alone, continuous monitoring systems that can easily be integrated with everyday life. Here, we exploit the design freedom offered by organic technologies to realize a reflective patch-type pulse oximetry sensor with ultralow power consumption.

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The CRISPR-Cas system is a well-established RNA-guided DNA editing technique widely used to modify genomic DNA sequences. I used the CRISPR-Cas9 system to change the second and third nucleotides of the triplet TCT of human in HepG2 cells to TAG to create an amber stop codon. The TCT triplet is the codon for Ser at the 172 position of TNSFSF9.

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In this work, we investigate whether S-nitrosoglutathione (GSNO)-conjugated hyaluronic acid-based self-assembled nanoparticles (GSNO-HANPs) can be useful as a chemosensitizing agent to improve the anticancer activity of doxorubicin (DOX). The GSNO-HANPs were prepared by aqueous assembly of GSNO-conjugated HA with grafted poly(lactide- co-glycolide). Aqueous GSNO stability shielded within the assembled environments of the GSNO-HANPs was greatly enhanced, compared to that of free GSNO.

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CD137 (4-1BB) is a T-cell costimulatory molecule, and agonstic CD137 antibodies are currently being evaluated in the clinic as cancer immunotherapy. Recently, it was found that CD137 mice or mice injected with agonistic anti-CD137 antibodies exhibit heightened antitumor responses, contrary to expectations based on other knowledge of CD137 function. Here, we report findings related to reverse signaling by CD137 ligand (CD137L) in antigen-presenting dendritic cells (DC) in tumors that address these paradoxical results.

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Mineral trioxide aggregate (MTA) is a calcium silicate-based bioactive material that has been extensively used in dentistry. MTA has been highlighted in its diverse biological functions and excellent clinical outcomes. However, limited insight into the intracellular signaling pathways has been provided to explain the biological activities of MTA.

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The sticker-type sensor system is proposed targeting ECG/PPG concurrent monitoring for cardiovascular diseases. The stickers are composed of two types: Hub and Sensor-node (SN) sticker. Low-power CMOS SoC for measuring ECG and PPG signal is hybrid integrated with organic light emitting diodes (OLEDs) and organic photo detector (OPD).

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We have examined the effect of progranulin (PGRN) on human T cell proliferation and its underlying mechanism. We show that PGRN inhibits the PHA-induced multiplication of T lymphocytes. It increases the number of iTregs when T lymphocytes are activated by PHA but does not do so in the absence of PHA.

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Article Synopsis
  • This study aimed to identify the best methods for isolating human dental pulp cells (HDPCs) for dental tissue engineering and regenerative endodontics.
  • Different methods (outgrowth, enzymatic digestion, and a combination) were used to isolate HDPCs, and their ability to differentiate into various cell types was assessed.
  • The results showed that isolation method affects differentiation, with specific methods favoring adipogenic or osteogenic transformations, which could enhance regenerative endodontic treatments.
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The success of endodontic treatment depends on the eradication of microorganisms from the root canal system and the prevention of reinfection. The purpose of this investigation was to evaluate the antibacterial and antibiofilm efficacy of N-acetylcysteine (NAC), an antioxidant mucolytic agent, as an intracanal medicament against selected endodontic pathogens. Minimum inhibitory concentrations (MICs) of NAC for Actinomyces naeslundii, Lactobacillus salivarius, Streptococcus mutans, and Enterococcus faecalis were determined using the broth microdilution method.

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Pathogen recognition receptors (PRRs) are a class of germ line-encoded receptors that recognize pathogen-associated molecular patterns (PAMPs). The activation of PRRs is crucial for the initiation of innate immunity, which plays a key role in first-line defense until more specific adaptive immunity is developed. PRRs differ in the signaling cascades and host responses activated by their engagement and in their tissue distribution.

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This study aimed to explore effects of static magnetic fields (SMFs) of moderate intensity (3-50 mT) as biophysical stimulators of proliferation and osteoblastic differentiation of human bone marrow-derived mesenchymal stem cells (MSCs). MSCs were exposed to SMFs of three intensities: 3, 15, and 50 mT. Proliferation was assessed by cell counting and bromodeoxyuridine incorporation, and differentiation by measuring alkaline phosphatase (ALP) activity, calcium content, mineralized nodule formation, and transcripts of osteogenic markers.

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