Publications by authors named "Kwak K"

Background: A nationwide Rehabilitation at Home Care Pilot Program for patients undergoing lower extremity orthopedic surgeries has been ongoing since 2020. The program was designed to improve clinical outcomes through early mobilization and rehabilitation after discharge. This study aimed to analyze the interim data to assess its effectiveness and suggest improvements, particularly for older patients who are more vulnerable compared to younger patients.

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Background And Aims: Lackluster results from recently completed gene therapy clinical trials of VEGF-A delivered by viral vectors have heightened the need to develop alternative delivery strategies. This study aims to demonstrate the pre-clinical efficacy and safety of extracellular vesicles (EVs) loaded with VEGF-A mRNA for the treatment of ischaemic vascular disease.

Methods: After encapsulation of full-length VEGF-A mRNA into fibroblast-derived EVs via cellular nanoporation (CNP), collected VEGF-A EVs were delivered into mouse models of ischaemic injury.

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Background & Aims: The impact of vitamin D deficiency (VDD) on cognition remains controversial. Evidences suggest that variability based on apolipoprotein E (APOE) ε4 status and gender, given APOE ε4's influence on vitamin D metabolism and women's heightened vitamin D sensitivity. We investigated the interplay between APOE ε4, gender, and VDD in cognitive decline among older adults.

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ConspectusWater-in-salt electrolytes (WiSEs) are promising electrolytes for next-generation lithium-ion batteries (LIBs), offering critical advantages like nonflammability and improved safety. These electrolytes have extremely high salt concentrations and exhibit unique solvation structures and transport mechanisms dominated by the formation of ion networks and aggregates. These ion networks are central to the performance of WiSEs, govern the transport properties and stability of the electrolyte, deviating from conventional dilute aqueous or organic electrolytes.

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As the trajectory of developing advanced electronics is shifting towards wearable electronics, various methods for implementing flexible and bendable devices capable of conforming to curvilinear surfaces have been widely investigated. In particular, achieving high-performance and stable flexible transistors remains a significant technical challenge, as transistors are fundamental components of electronics, playing a key role in overall performance. Among the wide range of candidates for flexible transistors, two-dimensional (2D) molybdenum disulfide (MoS)-based transistors have emerged as potential solutions to address these challenges.

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Optoelectronic devices require stable operation to detect repetitive visual information. In this study, endurable arrays based on heterojunction phototransistors composed of indium-gallium-zinc oxide (IGZO) with a low dark current and tin sulfide (SnS) capable of absorbing visible light are developed for image sensors. The tandem structure of IGZO/SnS/IGZO (ISI) enables stable operation under repetitive exposure to visible light by improving the transport ability of the photoexcited carriers through mitigated trap sites and their separation into each IGZO layer.

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The role of oxidative stress metabolism during hepatocellular carcinoma (HCC) formation potentially allows for positron emission tomography (PET) imaging of oxidative stress activity for early and precise HCC detection. However, there is currently limited data available on oxidative-stress-related PET imaging for longitudinal monitoring of the pathophysiological changes during HCC formation. This work aimed to explore PET-based longitudinal monitoring of oxidative stress metabolism and determine the sensitivity of [18F]-5-fluoroaminosuberic acid ([18F]FASu) for assessing pathophysiological processes in diethylnitrosamine (DEN) induced rat HCC.

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β-lactams have been the most successful antibiotics, but the rise of multi-drug resistant (MDR) bacteria threatens their effectiveness. Serine β-lactamases (SBLs), among the most common causes of resistance, are classified as A, C, and D, with numerous variants complicating structural and substrate spectrum comparisons. This study compares representative SBLs of these classes, focusing on the substrate-binding pocket (SBP).

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The rotational anisotropy of a molecule in a constrained environment is modeled by wobbling-in-a-cone (WIAC) motion, which describes the angular space sampled by the molecule. Recent polarization-selective IR pump-probe measurements have applied this model to phenylselenocyanate in amorphous polymers, aiming to probe the surrounding free volume. A faster rotational timescale was hypothesized to reflect the angular space within the static voids of the polymer matrix, while a slower timescale relates to constraint release by the polymer backbones.

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Article Synopsis
  • * Structural analysis showed that IDPs maintained their overall structure in DO, but increased hydrogen bonding and hydrophobic interactions in DO helped stabilize β-sheet fibrils.
  • * The results suggest that the unique properties of DO need to be considered in research involving protein interactions, as they significantly influence the structural and kinetic properties of proteins.
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Article Synopsis
  • The overuse of β-lactam antibiotics has led to the development of resistance, particularly due to enzymes called β-lactamases, which hydrolyze these antibiotics.
  • Research focused on variants of the OXA-10 β-lactamase revealed three mutations (G157D, A124T, N73S) that significantly improved hydrolytic activity against ceftazidime, a broad-spectrum cephalosporin antibiotic.
  • The study shows how single amino acid changes can impact drug resistance and suggests that understanding these mutations can help improve existing drugs and aid in the creation of new β-lactam antibiotics.
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Background: A decline in masticatory function may indicate brain dysfunction related to dementia, but the relationship between masticatory function and dementia risk remains unclear. This study aimed to investigate whether masticatory function is associated with the risk of cognitive decline and dementia.

Methods: Data were obtained from the nationwide prospective cohort study of randomly sampled community-dwelling Koreans aged ≥ 60 years.

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Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy is widely used to study condensed materials due to its convenient sample preparation and ability to avoid absorption saturation. Recently, it has been applied to and observations of chemical reactions within electrochemical devices, such as lithium-ion batteries. However, because ATR-FTIR spectroscopy relies on frequency-dependent attenuated reflectance, quantitative concentration measurements of chemical species using the Beer-Lambert law are challenging.

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Background: Determining brain atrophy is crucial for the diagnosis of neurodegenerative diseases. Despite detailed brain atrophy assessments using three-dimensional (3D) T1-weighted magnetic resonance imaging, their practical utility is limited by cost and time. This study introduces deep learning algorithms for quantifying brain atrophy using a more accessible two-dimensional (2D) T1, aiming to achieve cost-effective differentiation of dementia of the Alzheimer's type (DAT) from cognitively unimpaired (CU), while maintaining or exceeding the performance obtained with T1-3D individuals and to accurately predict AD-specific atrophy similarity and atrophic changes [W-scores and Brain Age Index (BAI)].

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B cells are the cornerstone of our body's defense system, producing precise antibodies and safeguarding immunological memory for future protection against pathogens. While we have a thorough understanding of how naïve B cells differentiate into plasma or memory B cells, the early B cell response to various antigens-whether self or foreign-remains a thrilling and evolving area of study. Advances in imaging have illuminated the molecular intricacies of B cell receptor (BCR) signaling, yet the dynamic nature of B cell activation continues to reveal new insights based on the nature of antigen exposure.

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Previous studies along the banks of the tidal Meghna River of the Ganges-Brahmaputra-Meghna Delta demonstrated the active sequestration of dissolved arsenic (As) on newly formed iron oxide minerals (Fe(III)-oxides) within riverbank sands. The sand with high solid-phase As (>500 mg/kg) was located within the intertidal zone where robust mixing occurs with oxygen-rich river water. Here we present new evidence that upwelling groundwater through a buried silt layer generates the dissolved products of reductive dissolution of Fe(III)-oxides, including As, while mobilization of DOC by upwelling groundwater prevents their reconstitution in the intertidal zone by lowering the redox state.

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: We aimed to elucidate the quantitative relationship between the neuromuscular blockade depth and intraoperative motor-evoked potential amplitudes. This prospective, single-arm, open-label, observational study was conducted at a single university hospital in Seoul, Korea, and included 100 adult patients aged ≥19 years undergoing brain tumor removal surgery under general anesthesia. We measured the neuromuscular blockade degree and motor-evoked potential amplitude in the deltoid, abductor pollicis brevis, tibialis anterior, and abductor hallucis muscles until dural opening.

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The current memory system is facing obstacles to improvement, and ReRAM is considered a powerful alternative. All-inorganic α-CsPbI perovskite-based ReRAM working by electrochemical mechanism is reported, but the electrochemically active electrode raised difficulty in long-term stable operation, and bulk α-CsPbI device can not show resistive switching behavior with an inert metal top electrode. Herein, by making the α-CsPbI into QDs and applying it to the device with inert Au as the top electrode, the devices working by valence change mechanism are successfully fabricated.

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Article Synopsis
  • Bronchus-associated lymphoid tissue (BALT) lymphoma, or BALToma, is a rare type of cancer that often has a slow progression, leading many patients to adopt a watch-and-wait strategy instead of immediate treatment.
  • A study of 67 patients from three hospitals in Korea found that patients who were just monitored or received minimal treatment had better long-term survival outcomes than those who underwent systemic chemotherapy: 10-year overall survival was 100% for the observation group compared to 71.7% for the chemotherapy group.
  • Factors like having both lungs involved or extrapulmonary organ involvement were associated with worse progression-free survival, indicating that such patients may need closer monitoring and potentially more aggressive treatment options.
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This study conducted real-time monitoring of size-resolved particle concentrations ranging from 9 nm to 10 μm simultaneously at four sites on the park ground and the roof of a five-story apartment buildings in the upwind and downwind areas of the Olympic Expressway next to apartment complex areas of Seoul, Korea. Using a positive matrix factorization model for source apportionment, eight factors were resolved at each monitoring site: four exhaust emissions of vehicles, one non-exhaust emission of vehicle, two regional sources, and one unknown source. After categorizing monitoring data into three cases by wind conditions, impact and contribution of each vehicle-related source on the local road to the roadside pollution was quantified and characterized by subtracting the urban background concentrations.

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Advancements in Li-ion battery (LIB) technology hinge on an understanding of Li-ion solvation and charge transport dynamics. Ultrafast two-dimensional infrared (2D-IR) spectroscopy has been used to investigate these dynamics in electrolytes by probing chemical exchange processes through time-dependent cross-peak analysis. However, accurate interpretation is complicated by factors such as vibrational energy transfer and molecular photothermal effect (MPTE), affecting cross-peak evolution.

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Background: The purpose of this study was to conduct survival analysis of teeth following clinical crown lengthening procedures (CLPs) and crown insertions via a retrospective cohort study.

Methods: Patient- and tooth-related data were collected from 268 participants who received CLPs from 2009 to 2015. The Kaplan-Meier curve and the log-rank tests were used to estimate the probability of survival and compare the survival probabilities among different variables.

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Article Synopsis
  • PEDOT:PSS films are being explored as a transparent electrode alternative to indium-tin oxide, thanks to their better transparency, flexibility, and stability, although their low conductivities present a challenge.
  • The study shows that treating PEDOT:PSS films with HSO solutions significantly boosts their electrical conductivity from 0.5 S/cm to 4358 S/cm, indicating enhanced performance.
  • Raman imaging reveals microstructural changes in the films after treatment, with a shift in C═C stretching modes suggesting improved crystallinity and conformation, providing a useful method for assessing the structural properties of conductive films.
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  • The stability of lithium metal batteries (LMBs) is significantly influenced by the composition of the solid electrolyte interphase (SEI) on lithium metal anodes, which was improved in this study through the use of bisalts additives in carbonate-based electrolytes.
  • The successful formulation led to the creation of an inorganic-rich SEI layer containing compounds like LiF, polythionate, and LiN, which also helped reduce corrosion of aluminum current collectors.
  • The bisalts additives, specifically EL-DO, demonstrated exceptional battery performance, achieving high coulombic efficiency and stable discharge capacities, indicating their potential to enhance both LMBs and lithium-ion batteries compared to other electrolytes.
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Virion-mediated outbreaks are imminent and despite rapid responses, continue to cause adverse symptoms and death. Therefore, tunable, sensitive, high-throughput assays are needed to help diagnose future virion-mediated outbreaks. Herein, it is developed a tunable in situ assay to selectively enrich virions and extracellular vesicles (EVs) and simultaneously detect antigens and nucleic acids at a single-particle resolution.

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