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  1. Article ; Online: A lumped-parameter model of the free-flooded ring transducer array.

    Lee, Junsu / Been, Kyounghun / Lee, Haksue / Seo, Heeseon / Moon, Wonkyu

    The Journal of the Acoustical Society of America

    2024  Volume 155, Issue 1, Page(s) 615–628

    Abstract: The free-flooded ring (FFR) transducer is an extensively used ring-type acoustic transducer in underwater environments owing to its broad operating frequency bandwidth and small size. However, achieving high sound pressure levels with a single FFR ... ...

    Abstract The free-flooded ring (FFR) transducer is an extensively used ring-type acoustic transducer in underwater environments owing to its broad operating frequency bandwidth and small size. However, achieving high sound pressure levels with a single FFR transducer is often difficult, thus necessitating the construction of vertically arranged FFR transducer arrays. This study presents a comprehensive analysis of the electrical and acoustic characteristics of an FFR transducer array by considering the mutual radiation load and the effects of gaps between adjacent piezoelectric rings. The lumped-parameter models of the piezoelectric ring, cylindrical cavity, cylindrical gap, and radiation impedance constitute an entire impedance matrix. The radiation impedance matrix for the FFR transducer array is calculated using the Helmholtz-Kirchhoff integral formula by considering the interaction of the FFR surfaces with the surrounding fluid medium. The proposed model predicts the resonance peaks in the admittance and transmitted voltage response (TVR) with a relative error of 5%, and the TVR level within a 3 dB range. Detailed analyses of a four-FFR transducer array reveal that a wider gap between each FFR leads to a decreased chance of negative conductance and broader operating bandwidth. The proposed model offers valuable insights into the design of FFR transducer arrays.
    Language English
    Publishing date 2024-01-23
    Publishing country United States
    Document type Journal Article
    ZDB-ID 219231-7
    ISSN 1520-8524 ; 0001-4966
    ISSN (online) 1520-8524
    ISSN 0001-4966
    DOI 10.1121/10.0024462
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Dual-Element Intravascular Ultrasound Transducer for Tissue Harmonic Imaging and Frequency Compounding: Development and Imaging Performance Assessment.

    Lee, Junsu / Chang, Jin Ho

    IEEE transactions on bio-medical engineering

    2019  Volume 66, Issue 11, Page(s) 3146–3155

    Abstract: Objective: For accurate diagnosis of atherosclerosis, the high spatial and contrast resolutions of intravascular ultrasound (IVUS) images are a key requirement. Increasing the center frequency of IVUS is a simple solution to meet this requirement. ... ...

    Abstract Objective: For accurate diagnosis of atherosclerosis, the high spatial and contrast resolutions of intravascular ultrasound (IVUS) images are a key requirement. Increasing the center frequency of IVUS is a simple solution to meet this requirement. However, this leads to a reduction in imaging depth due to the frequency-dependent attenuation of ultrasound. Here, we report a recently developed dual-element IVUS transducer for tissue harmonic imaging (THI) and frequency compounding to increase the spatial and contrast resolutions of IVUS images, while maintaining the imaging depth to assess the overall morphological change of blood vessels.
    Methods: One 35-MHz element is used for producing general IVUS images and the other 70-MHz element is for receiving the second harmonic signals induced by the 35-MHz ultrasound. The fundamental and second harmonic signals can also be used for frequency compound imaging to further improve contrast resolution. The spatial and contrast resolutions achieved by the developed transducer were evaluated through wire and tissue-mimicking phantom imaging tests. Additionally, the images of a stent deployed in a tissue-mimicking phantom and an excised pig artery were acquired to assess clinical usefulness of the transducer.
    Results: The results demonstrated that the developed IVUS transducer enables us to simultaneously examine the overall morphological change of blood vessels by the 35-MHz ultrasound images and the near vessel layers such as the intima, the media, and the adventitia by either THI or compound images with high spatial and contrast resolutions. In addition, the developed transducer facilitates the simultaneous acquisition of 35- and 70-MHz fundamental images when needed.
    Conclusion: The developed dual-element IVUS transducer makes it possible to fully realize the potential benefits of IVUS in the diagnosis of atherosclerosis.
    MeSH term(s) Animals ; Arteries/diagnostic imaging ; Equipment Design ; Image Processing, Computer-Assisted/methods ; Phantoms, Imaging ; Signal Processing, Computer-Assisted ; Stents ; Swine ; Transducers ; Ultrasonography, Interventional/instrumentation ; Ultrasonography, Interventional/methods
    Language English
    Publishing date 2019-02-27
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 160429-6
    ISSN 1558-2531 ; 0018-9294
    ISSN (online) 1558-2531
    ISSN 0018-9294
    DOI 10.1109/TBME.2019.2901005
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 425: Show issues Location:
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  3. Article ; Online: Opioids-induced inhibition of HERG ion channels and sudden cardiac death, a systematic review of current literature.

    El Sherbini, Adham / Liblik, Kiera / Lee, Junsu / Baranchuk, Adrian / Zhang, Shetuan / El-Diasty, Mohammad

    Trends in cardiovascular medicine

    2023  

    Abstract: Background: It is estimated that over 60 million individuals regularly use opioids globally, with opioid use disorder increasing substantially in the past decade. Several reports have linked sudden cardiac death, QTc prolongation, and other adverse ... ...

    Abstract Background: It is estimated that over 60 million individuals regularly use opioids globally, with opioid use disorder increasing substantially in the past decade. Several reports have linked sudden cardiac death, QTc prolongation, and other adverse cardiovascular outcomes with opioid use through their inhibitory effect on the human ether-a-go-go-related gene (HERG) ion channel. Therefore, understanding this underlying mechanism may be critical for risk prevention and management in prescribing opioids and treating patients with opioid dependency.
    Aim: The present systematic review summarizes the current literature on the impact of opioids-induced inhibition of HERG channel function and its relationship with sudden cardiac death, QTc prolongation, and other cardiovascular adverse effects.
    Methods: A systematic review was conducted of the databases PubMed, EMBASE, Cochrane, and ClinicalTrials.gov of primary studies that reported the effects of opioids on HERG channel function and associated cardiovascular outcomes.
    Results: The search identified 1,546 studies, of which 12 were finally included for data extraction. Based on the current literature, methadone, oliceridine, l-α-acetylmethadol (LAAM), and fentanyl were found to inhibit the HERG channel function and were associated with QTc prolongation. However, other opioids such as morphine, codeine, tramadol, and buprenorphine were not associated with inhibition of HERG channels or QTc prolongation. Additional cardiac outcomes associated with opioid related HERG channels dysfunction included sudden cardiac death and Torsade de Pointes.
    Conclusion: Our findings suggest that certain opioid consumption may result in the inhibition of HERG channels, subsequently prolonging the QTc interval and increasing patient susceptibility to sudden cardiac death.
    Language English
    Publishing date 2023-04-02
    Publishing country United States
    Document type Journal Article ; Review
    ZDB-ID 1097434-9
    ISSN 1873-2615 ; 1050-1738
    ISSN (online) 1873-2615
    ISSN 1050-1738
    DOI 10.1016/j.tcm.2023.03.006
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 3419: Show issues Location:
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  4. Article ; Online: Effectiveness of synthetic aperture focusing and coherence factor weighting for intravascular ultrasound imaging.

    Kang, Sungwoo / Lee, Junsu / Chang, Jin Ho

    Ultrasonics

    2021  Volume 113, Page(s) 106364

    Abstract: Synthetic aperture focusing (SAF) and coherence factor weighting (CFW) have been used to improve the lateral resolution of ultrasound images. Although the two methods are effective for array-based ultrasound imaging, many researchers have also employed ... ...

    Abstract Synthetic aperture focusing (SAF) and coherence factor weighting (CFW) have been used to improve the lateral resolution of ultrasound images. Although the two methods are effective for array-based ultrasound imaging, many researchers have also employed the methods for single-element-based imaging including intravascular ultrasound (IVUS) imaging. For single-element-based imaging, CFW is generally calculated from the scanlines obtained by SAF and applied to the scanline obtained after coherent summation of the SAF delayed scanlines, which is called a SAF-CFW method. In the paper, a theoretical model was derived to explore the effectiveness of SAF and CFW for single-element-based imaging, and the model was used to explain that SAF is not effective for IVUS imaging in terms of enhancing the spatial resolution, although it has the advantage of improving a contrast-to-noise ratio (CNR). This means that the SAF-CFW method is not optimal for improving the spatial resolution of IVUS imaging. In contrast, it was found in simulations and experiments that applying CFW to the target scanline itself is beneficial for the spatial resolution rather than a coherent summed scanline for IVUS SAF imaging, but CNR was not as good as SAF and SAF-CFW. As a result of both simulation and experimentation, it could be concluded that focused IVUS transducers without the application of those methods may be more advantageous to improve the spatial and contrast resolution simultaneously, considering the system complexity in the implementation of such imaging methods.
    MeSH term(s) Computer Simulation ; Equipment Design ; Image Enhancement/methods ; Image Processing, Computer-Assisted ; Phantoms, Imaging ; Signal Processing, Computer-Assisted ; Transducers ; Ultrasonography, Interventional/methods
    Language English
    Publishing date 2021-01-22
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 200839-7
    ISSN 1874-9968 ; 0041-624X
    ISSN (online) 1874-9968
    ISSN 0041-624X
    DOI 10.1016/j.ultras.2021.106364
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.B 1133: Show issues Location:
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  5. Article ; Online: A 40-MHz Ultrasound Transducer with an Angled Aperture for Guiding Percutaneous Revascularization of Chronic Total Occlusion: A Feasibility Study.

    Lee, Junsu / Chang, Jin Ho

    Sensors (Basel, Switzerland)

    2018  Volume 18, Issue 11

    Abstract: Complete blockage of a coronary artery, called chronic total occlusion (CTO), frequently occurs due to atherosclerosis. To reopen the obstructed blood vessels with a stent, guidewire crossing is performed with the help of angiography that can provide the ...

    Abstract Complete blockage of a coronary artery, called chronic total occlusion (CTO), frequently occurs due to atherosclerosis. To reopen the obstructed blood vessels with a stent, guidewire crossing is performed with the help of angiography that can provide the location of CTO lesions and the image of guidewire tip. Since angiography is incapable of imaging inside a CTO lesion, the surgeons are blind during guidewire crossing. For this reason, the success rate of guidewire crossing relies upon the proficiency of the surgeon, which is considerably reduced from 69.0% to 32.5% if extensive calcification, not penetrated by a guidewire, exists in CTO lesions. In this paper, a recently developed 40-MHz forward-looking intravascular ultrasound (FL⁻IVUS) transducer to visualize calcification within CTO lesions is reported. This transducer consists of a single element angled aperture and a guidewire passage. The aperture is spherically deformed to have a focal length of 3 mm in order to improve spatial resolution of FL⁻IVUS images. The angle between the beam direction and the axis of rotation is designed to be 30° to effectively visualize calcification within a CTO lesion as well as the blood vessel wall. The experimental results demonstrated that the developed FL⁻IVUS transducer facilitates visualization of calcification within CTO lesions and makes it possible to help the surgeon make decisions about whether to push the guidewire in order to cross the lesion or to change the surgical procedure.
    Language English
    Publishing date 2018-11-21
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2052857-7
    ISSN 1424-8220 ; 1424-8220
    ISSN (online) 1424-8220
    ISSN 1424-8220
    DOI 10.3390/s18114079
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article: Inhibitory effects of nicotinic acid, glycine, and other food additives on biogenic amine formation in Baechu kimchi fermentation

    Jin, Young Hun / Lee, Junsu / Pawluk, Alixander Mattay / Mah, Jae-Hyung

    Lebensmittel-Wissenschaft + [i.e. und] Technologie. 2022 Feb. 01, v. 155

    2022  

    Abstract: The current study was performed to reduce biogenic amine (BA) content in Baechu (napa cabbage) kimchi using food additives for prevention of BA-related risks. Through in-vitro experiments, among 9 selected additives, nicotinic acid and glycine exhibited ... ...

    Abstract The current study was performed to reduce biogenic amine (BA) content in Baechu (napa cabbage) kimchi using food additives for prevention of BA-related risks. Through in-vitro experiments, among 9 selected additives, nicotinic acid and glycine exhibited the highest inhibitory effects on the tyramine production of a prolific tyramine-producing Levilactobacillus brevis BC1M20, showing inhibition of up to 100% and 78%, respectively, depending on the concentrations tested, compared to the control. In Baechu kimchi fermentation experiments, tyramine content in kimchi prepared with L. brevis BC1M20 and either 1% nicotinic acid or 5% glycine was dramatically reduced by 90.66% and 82.51%, respectively, compared to naturally fermented kimchi. When compared to kimchi prepared with the inoculum and no food additives, remarkable tyramine reductions of 87.28% and 76.20% were achieved by 1% nicotinic acid and 5% glycine, respectively. With the additives, content of 3–5 other BAs was also considerably reduced by 22.57%–76.64%. Such reductions were likely attributed to the inhibition of growth and/or amino acid decarboxylase activity of BA-producing bacteria. Consequently, the findings of this study can be valuable in the prevention of BA-related food safety issues in kimchi.
    Keywords cabbage ; fermentation ; food safety ; inoculum ; kimchi ; niacin ; tyramine
    Language English
    Dates of publication 2022-0201
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 241369-3
    ISSN 0460-1173 ; 0023-6438
    ISSN 0460-1173 ; 0023-6438
    DOI 10.1016/j.lwt.2021.112921
    Database NAL-Catalogue (AGRICOLA)

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  7. Article: Reduction in Biogenic Amine Content in

    Lee, Junsu / Jin, Young Hun / Pawluk, Alixander Mattay / Mah, Jae-Hyung

    Microorganisms

    2021  Volume 9, Issue 12

    Abstract: This study was performed to mine biogenic amine (BA)-degrading lactic acid bacteria (LAB) from kimchi and to investigate the effects of the LAB strains on BA reduction ... ...

    Abstract This study was performed to mine biogenic amine (BA)-degrading lactic acid bacteria (LAB) from kimchi and to investigate the effects of the LAB strains on BA reduction in
    Language English
    Publishing date 2021-12-13
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2720891-6
    ISSN 2076-2607
    ISSN 2076-2607
    DOI 10.3390/microorganisms9122570
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  8. Article ; Online: Pseudo-Hydrodynamic Flow of Quasiparticles in Semimetal WTe

    Choi, Young-Gwan / Doan, Manh-Ha / Ngoc, Luu Ly Pham / Lee, Junsu / Choi, Gyung-Min / Chernodub, Maxim Nikolaevich

    Small (Weinheim an der Bergstrasse, Germany)

    2023  Volume 19, Issue 27, Page(s) e2206604

    Abstract: Recently, much interest has emerged in fluid-like electric charge transport in various solid-state systems. The hydrodynamic behavior of the electronic fluid reveals itself as a decrease of the electrical resistance with increasing temperature (the ... ...

    Abstract Recently, much interest has emerged in fluid-like electric charge transport in various solid-state systems. The hydrodynamic behavior of the electronic fluid reveals itself as a decrease of the electrical resistance with increasing temperature (the Gurzhi effect) in narrow channels, polynomial scaling of the resistance as a function of the channel width, violation of the Wiedemann-Franz law supported by the emergence of the Poiseuille flow. Similar to whirlpools in flowing water, the viscous electronic flow generates vortices, resulting in abnormal sign-changing electrical response driven by backflow. However, the question of whether the long-ranged sign-changing electrical response can be produced by a mechanism other than hydrodynamics has not been addressed so far. Here polarization-sensitive laser microscopy is used to demonstrate the emergence of visually similar abnormal sign-alternating patterns in semi-metallic tungsten ditelluride at room temperature where this material does not exhibit true hydrodynamics. It is found that the neutral quasiparticle current consisting of electrons and holes obeys an equation remarkably similar to the Navier-Stokes equation. In particular, the momentum relaxation is replaced by the much slower process of quasiparticle recombination. This pseudo-hydrodynamic flow of quasiparticles leads to a sign-changing charge accumulation pattern via different diffusivities of electrons and holes.
    Language English
    Publishing date 2023-03-23
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2168935-0
    ISSN 1613-6829 ; 1613-6810
    ISSN (online) 1613-6829
    ISSN 1613-6810
    DOI 10.1002/smll.202206604
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Yb Substitution and Ultralow Thermal Conductivity of the Ca

    Hong, Yeongjin / Lee, Junsu / Seo, Donghwan / Choi, Myung-Ho / Yox, Philip / Kovnir, Kirill / Miller, Gordon J / Ok, Kang Min / You, Tae-Soo

    Inorganic chemistry

    2023  Volume 62, Issue 26, Page(s) 10141–10151

    Abstract: A series of Yb-substituted Zintl phases in the ... ...

    Abstract A series of Yb-substituted Zintl phases in the Ca
    Language English
    Publishing date 2023-06-21
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1484438-2
    ISSN 1520-510X ; 0020-1669
    ISSN (online) 1520-510X
    ISSN 0020-1669
    DOI 10.1021/acs.inorgchem.3c00615
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Epigenetic MicroRNAs as Prognostic Markers of Postoperative Atrial Fibrillation: A Systematic Review.

    Lee, Junsu / Lee, Hyunmin / Sherbini, Adham El / Baghaie, Leili / Leroy, Fleur / Abdel-Qadir, Husam / Szewczuk, Myron R / El-Diasty, Mohammad

    Current problems in cardiology

    2023  Volume 49, Issue 1 Pt C, Page(s) 102106

    Abstract: Postoperative atrial fibrillation (POAF) is a common complication after cardiac surgery, increasing the risk for adverse outcomes such as perioperative and long-term mortality, stroke, myocardial infarction, and other thromboembolic events. Epigenetic ... ...

    Abstract Postoperative atrial fibrillation (POAF) is a common complication after cardiac surgery, increasing the risk for adverse outcomes such as perioperative and long-term mortality, stroke, myocardial infarction, and other thromboembolic events. Epigenetic biomarkers show promise as prognostic tools for POAF. Epigenetic changes, such as DNA methylation, histone modification, and microRNAs (miRNA), can result in altered gene expression and the development of various pathological conditions. This systematic review aims to present the current literature on the association between various epigenetic markers and the development of POAF following cardiac surgery. Here, an electronic literature search was performed using MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, and Google Scholar to identify studies that reported the role of epigenetic markers in the development of POAF. Five of the 6 studies focused on miRNAs and their association with POAF. In POAF patients, the expression of miR-1 and miR-483-5p were upregulated in the right atrial appendage (RAA), while the levels of miR-133A, miR-208a, miR-23a, miR-26a, miR-29a, miR-29b, and miR-29c were decreased in the RAA and venous blood. One study examined cytosines followed by guanines (CpGs) as DNA methylation markers. Across all studies, 488 human subjects who had undergone cardiac surgery were investigated, and 195 subjects (39.9%) developed new-onset POAF. The current literature suggests that miRNAs may play a role in predicting the development of atrial fibrillation after cardiac surgery. However, more robust clinical data are required to justify their role in routine clinical practice.
    MeSH term(s) Humans ; Atrial Fibrillation/etiology ; Atrial Fibrillation/genetics ; Cardiac Surgical Procedures/adverse effects ; Epigenesis, Genetic ; MicroRNAs/genetics ; Prognosis ; Risk Factors
    Chemical Substances MicroRNAs
    Language English
    Publishing date 2023-09-22
    Publishing country Netherlands
    Document type Journal Article ; Systematic Review
    ZDB-ID 441230-8
    ISSN 1535-6280 ; 0146-2806
    ISSN (online) 1535-6280
    ISSN 0146-2806
    DOI 10.1016/j.cpcardiol.2023.102106
    Database MEDical Literature Analysis and Retrieval System OnLINE

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