Publications by authors named "Kyungho Yoon"

. The purpose of this study is to analytically derive and validate a novel radiation energy conservation principle for dose mapping via deformable image registration (DIR)..

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Background And Objective: Transcranial focused ultrasound (tFUS) is an emerging non-invasive therapeutic technology that offers new brain stimulation modality. Precise localization of the acoustic focus to the desired brain target throughout the procedure is needed to ensure the safety and effectiveness of the treatment, but acoustic distortion caused by the skull poses a challenge. Although computational methods can provide the estimated location and shape of the focus, the computation has not reached sufficient speed for real-time inference, which is demanded in real-world clinical situations.

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Super-resolution (SR) techniques have revolutionized the field of biomedical applications by detailing the structures at resolutions beyond the limits of imaging or measuring tools. These techniques have been applied in various biomedical applications, including microscopy, magnetic resonance imaging (MRI), computed tomography (CT), X-ray, electroencephalogram (EEG), ultrasound, etc. SR methods are categorized into two main types: traditional non-learning-based methods and modern learning-based approaches.

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Transcranial focused ultrasound (tFUS) has emerged as a new mode of non-invasive brain stimulation (NIBS), with its exquisite spatial precision and capacity to reach the deep regions of the brain. The placement of the acoustic focus onto the desired part of the brain is critical for successful tFUS procedures; however, acoustic wave propagation is severely affected by the skull, distorting the focal location/shape and the pressure level. High-resolution (HR) numerical simulation allows for monitoring of acoustic pressure within the skull but with a considerable computational burden.

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Transport of interstitial fluid and solutes plays a critical role in clearing metabolic waste from the brain. Transcranial application of focused ultrasound (FUS) has been shown to promote localized cerebrospinal fluid solute uptake into the brain parenchyma; however, its effects on the transport and clearance of interstitial solutes remain unknown. We demonstrate that pulsed application of low-intensity FUS to the rat brain enhances the transport of intracortically injected fluorescent tracers (ovalbumin and high molecular-weight dextran), yielding greater parenchymal tracer volume distribution compared to the unsonicated control group (ovalbumin by 40.

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Contrary to conditioning a Focused Ultrasound (FUS) beam to sonicate a localized region of the human brain, the goal of this investigation was to explore the prospect of distributing homogeneous ultrasound energy over the entire brain space with a large cranium-wide ultrasound beam. Recent ultrasound preclincal studies utilizing large or whole brain stimulation regions create a demand for expanding the treatment envelope of transcranial pulsed-low intensity ultrasound towards Global Brain Sonication (GBS) for potential human investigation. Here, we conduct ultrasound field characterizations when transmitting pulsed ultrasound through human skull specimens using a 1-3 piezocomposite planar transducer operating at 464 kHz with an active single-element surface of 30 × 30 cm.

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Background And Objective: Transcranial focused ultrasound (tFUS) has emerged as a new non-invasive brain stimulation (NIBS) modality, with its exquisite ability to reach deep brain areas at a high spatial resolution. Accurate placement of an acoustic focus to a target region of the brain is crucial during tFUS treatment; however, the distortion of acoustic wave propagation through the intact skull casts challenges. High-resolution numerical simulation allows for monitoring of the acoustic pressure field in the cranium but also demands extensive computational loads.

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Halide solid electrolytes have recently emerged as a promising option for cathode-compatible catholytes in solid-state batteries (SSBs), owing to their superior oxidation stability at high voltage and their interfacial stability. However, their day- to month-scale aging at the cathode interface has remained unexplored until now, while its elucidation is indispensable for practical deployment. Herein, the stability of halide solid electrolytes (e.

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Transcranial focused ultrasound (tFUS) has gained attention in the field of brain stimulation owing to its non-invasive neurotherapeutic potentials. However, complex interactions between acoustic waves and the cranium may introduce misalignment of the acoustic focus from a geometric target location, thus, necessitate on-site feedback of real-time navigational information of the transducer (spatial coordinates and angular orientation) for the operators to accurately place the acoustic focus to the desired brain area. In this study, we propose a deep-learning-based network model that can provide spatial navigational information of a single-element FUS transducer with respect to the targeted brain region.

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Efficient transport of solutes in the cerebrospinal fluid (CSF) plays a critical role in their clearance from the brain. Convective bulk flow of solutes in the CSF in the perivascular space (PVS) is considered one of the important mechanisms behind solute movement in the brain, before their ultimate drainage to the systemic lymphatic system. Acoustic pressure waves can impose radiation force on a medium in its path, inducing localized and directional fluidic flow, known as acoustic streaming.

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All-solid-state batteries are a potential game changer in the energy storage market; however, their practical employment has been hampered by premature short circuits caused by the lithium dendritic growth through the solid electrolyte. Here, we demonstrate that a rational layer-by-layer strategy using a lithiophilic and electron-blocking multilayer can substantially enhance the performance/stability of the system by effectively blocking the electron leakage and maintaining low electronic conductivity even at high temperature (60°C) or under high electric field (3 V) while sustaining low interfacial resistance (13.4 ohm cm).

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Background And Objective: Focused ultrasound (FUS) has been receiving growing attention as a noninvasive brain stimulation tool because of its superior spatial specificity and depth penetrability. However, the large mismatch of acoustic properties between the skull and water can disrupt and shift the acoustic focus in the brain. In this paper, we present a numerical method to find the optimal location of a single-element FUS transducer, which creates focus on the target region.

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Lithium metal batteries using solid electrolytes are considered to be the next-generation lithium batteries due to their enhanced energy density and safety. However, interfacial instabilities between Li-metal and solid electrolytes limit their implementation in practical batteries. Herein, Li-metal batteries using tailored garnet-type LiLaZrO (LLZO) solid electrolytes is reported, which shows remarkable stability and energy density, meeting the lifespan requirements of commercial applications.

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Sonicating deep brain regions with pulsed focused ultrasound using magnetic resonance imaging-guided neuronavigation single-element piezoelectric transducers is a new area of exploration for neuromodulation. Upper cranial nerves such as the trigeminal nerve and other nerves responsible for sensory/motor functions in the head may be potential targets for ultrasound pain therapy. The location of upper cranial nerves close to the skull base poses additional challenges when compared with conventional cortical or middle brain targets.

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Purpose: The purpose of this study was to evaluate if transcutaneous application of low-intensity ultrasound can locally enhance the effects of finasteride on hair growth in a murine model of androgenic alopecia (AA).

Methods: AA mice (injected twice per week with testosterone enanthate, n=11), under daily oral administration of finasteride, received 1-MHz ultrasound for 1 hour at the unilateral thigh area five times per week for 5 weeks. Non-thermal and non-cavitational ultrasound was delivered in a pulsed manner (55-ms pulse duration with a repetition frequency of 4 Hz).

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Remarkable improvement of the ionic conductivity of inorganic solid electrolytes (SEs) exceeding 10 mS cm at room temperature has opened up the opportunities to realize the commercialization of solid-state batteries (SSBs). The transition to the intrinsically inflammable SEs also promises that SSBs would successfully utilize lithium metal anode thus achieving the high-energy-density lithium metal batteries without the risk of a safety hazard. However, the practical operation of solid-state lithium metal batteries (SSLMBs) still faces the challenges of the poor cycle stability and the low energy efficiency, which are coupled with the interface stability and even with the dendrite growth of lithium metal.

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Article Synopsis
  • Transcranial pulsed low-intensity focused ultrasound (FUS) was tested on awake sheep to see how it affects brain areas, specifically targeting the motor cortex and thalamus.
  • The study measured muscle responses using electromyography (EMG), finding that excitation from FUS increased EMG amplitude in the limb opposite to the sonication site, while suppressive sonication decreased EMG signals during movement.
  • Behavioral and histological assessments showed no brain damage from the application, indicating that FUS can safely and reversibly modulate brain activity, suggesting its future potential in combined therapeutic and diagnostic applications (theragnostics).
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  • High-intensity ultrasound enhances skin permeability for hydrophobic medications like lidocaine, while low-intensity focused ultrasound (FUS) temporarily disrupts drug-plasma protein binding to boost anesthetic effects of hydrophilic lidocaine hydrochloride.
  • In experiments, FUS was applied using a specific pulse mode to test its effects on lidocaine concentration and pain response in rats.
  • Results showed that FUS increased the amount of unbound lidocaine, indicating enhanced availability, but applying FUS alone did not affect sensory nerve responses, whereas lidocaine administration did decrease them.
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The development of a compliant neural probe is necessary to achieve chronic implantation with minimal signal loss. Although fiber-based neural probes fabricated by the thermal drawing process have been proposed as a solution, their long-term effect on the brain has not been thoroughly investigated. Here, we examined the mechanical interaction of thermally drawn fiber implants with neural tissue through computational and histological analyses.

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  • Plasma protein binding (PPB) significantly influences the effectiveness of drugs targeting the central nervous system by impacting the amount of drug that can cross the blood-brain barrier (BBB).
  • Researchers used a technique called focused ultrasound (FUS) to non-invasively disrupt PPB of phenytoin, an anti-epileptic drug, resulting in a 27.7% increase in the unbound drug concentration.
  • In animal studies, targeted FUS treatment of one side of the brain led to enhanced drug uptake in that side without overheating or damaging the BBB, paving the way for potential new approaches in drug delivery.
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Article Synopsis
  • There is a growing demand for region-specific, noninvasive treatments for neurologic and psychiatric disorders, with transcranial focused ultrasound technology emerging as a promising option.
  • This technology can temporarily and reversibly disrupt the blood-brain barrier with high precision, allowing for the delivery of therapeutic agents directly into the brain.
  • Ongoing research is expanding from small animals to nonhuman primates and humans, focusing on the technique's efficacy, safety, and potential for clinical application in treating various neurologic conditions.
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Article Synopsis
  • * The study focused on the effects of FUS on brain excitability in sheep, testing different sonication parameters on the primary sensorimotor area and thalamus.
  • * Results indicated that FUS can transiently and safely modulate brain activity without causing tissue damage, supporting further human research.
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  • Researchers have developed a non-invasive technique using focused ultrasound (FUS) and microbubble agents to temporarily open the blood-brain barrier (BBB) in sheep brains for potential medical applications.
  • Dynamic contrast-enhanced MRI confirmed the localized opening of the BBB, with specific acoustic pressures affecting permeability; lower pressure (0.48 MPa) was effective, while higher pressure (0.58 MPa) caused minor hemorrhage.
  • The study found no abnormal behavior in animals during the two-month recovery period, suggesting that careful monitoring is necessary to ensure safety when applying this method to humans.
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The thermodynamic instability of the LiCoO layered structure at >0.5Li extraction has been considered an obstacle for the reversible utilization of its near theoretical capacity at high cutoff voltage (>4.6 V vs Li/Li) in lithium-ion batteries.

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