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"Yoon, Sangpil"
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Advancing Sustainable Mining: A Comparative Analysis of Research Trends and Knowledge Spillover in Critical Mineral Exploration
2026
As global demand for critical minerals intensifies with the expansion of energy transition technologies and advanced manufacturing, developing sustainable and efficient exploration strategies has become a national priority. In this shift, AI-driven exploration technologies are emerging as a transformative force, reshaping how mineral resources are discovered, assessed, and managed. This study analyzes the global research landscape in critical mineral exploration by examining patent and scientific publication data to evaluate both research efficiency and knowledge spillover capacity. Using data envelopment analysis and super-efficiency modeling, we compare national R&D performance, identify leading countries, and quantify diffusion dynamics. The results reveal significant disparities: countries such as the United States, South Korea, and Canada demonstrate high research efficiency and strong spillover effects, supported by active innovation ecosystems and technological adoption. In contrast, resource-rich nations including China, Australia, and Russia show limited diffusion due to weaker AI-based innovation incentives and insufficient industry–academia collaboration. Italy stands out as an effective model of policy-driven R&D utilization and technological diffusion. These findings highlight the strategic importance of combining AI-enabled exploration, qualitative research impact, and international cooperation. The study offers policy implications for countries seeking to strengthen resource security and enhance competitiveness through sustainable and innovation-driven mineral exploration.
Journal Article
FRET-Based Ca2+ Biosensor Single Cell Imaging Interrogated by High-Frequency Ultrasound
2020
Fluorescence resonance energy transfer (FRET)-based biosensors have advanced live cell imaging by dynamically visualizing molecular events with high temporal resolution. FRET-based biosensors with spectrally distinct fluorophore pairs provide clear contrast between cells during dual FRET live cell imaging. Here, we have developed a new FRET-based Ca2+ biosensor using EGFP and FusionRed fluorophores (FRET-GFPRed). Using different filter settings, the developed biosensor can be differentiated from a typical FRET-based Ca2+ biosensor with ECFP and YPet (YC3.6 FRET Ca2+ biosensor, FRET-CFPYPet). A high-frequency ultrasound (HFU) with a carrier frequency of 150 MHz can target a subcellular region due to its tight focus smaller than 10 µm. Therefore, HFU offers a new single cell stimulations approach for FRET live cell imaging with precise spatial resolution and repeated stimulation for longitudinal studies. Furthermore, the single cell level intracellular delivery of a desired FRET-based biosensor into target cells using HFU enables us to perform dual FRET imaging of a cell pair. We show that a cell pair is defined by sequential intracellular delivery of the developed FRET-GFPRed and FRET-CFPYPet into two target cells using HFU. We demonstrate that a FRET-GFPRed exhibits consistent 10–15% FRET response under typical ionomycin stimulation as well as under a new stimulation strategy with HFU.
Journal Article
Acoustic-transfection for genomic manipulation of single-cells using high frequency ultrasound
2017
Efficient intracellular delivery of biologically active macromolecules has been a challenging but important process for manipulating live cells for research and therapeutic purposes. There have been limited transfection techniques that can deliver multiple types of active molecules simultaneously into single-cells as well as different types of molecules into physically connected individual neighboring cells separately with high precision and low cytotoxicity. Here, a high frequency ultrasound-based remote intracellular delivery technique capable of delivery of multiple DNA plasmids, messenger RNAs, and recombinant proteins is developed to allow high spatiotemporal visualization and analysis of gene and protein expressions as well as single-cell gene editing using clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein-9 nuclease (Cas9), a method called acoustic-transfection. Acoustic-transfection has advantages over typical sonoporation because acoustic-transfection utilizing ultra-high frequency ultrasound over 150 MHz can directly deliver gene and proteins into cytoplasm without microbubbles, which enables controlled and local intracellular delivery to acoustic-transfection technique. Acoustic-transfection was further demonstrated to deliver CRISPR-Cas9 systems to successfully modify and reprogram the genome of single live cells, providing the evidence of the acoustic-transfection technique for precise genome editing using CRISPR-Cas9.
Journal Article
Label-free analysis of the characteristics of a single cell trapped by acoustic tweezers
2017
Single-cell analysis is essential to understand the physical and functional characteristics of cells. The basic knowledge of these characteristics is important to elucidate the unique features of various cells and causative factors of diseases and determine the most effective treatments for diseases. Recently, acoustic tweezers based on tightly focused ultrasound microbeam have attracted considerable attention owing to their capability to grab and separate a single cell from a heterogeneous cell sample and to measure its physical cell properties. However, the measurement cannot be performed while trapping the target cell, because the current method uses long ultrasound pulses for grabbing one cell and short pulses for interrogating the target cell. In this paper, we demonstrate that short ultrasound pulses can be used for generating acoustic trapping force comparable to that with long pulses by adjusting the pulse repetition frequency (PRF). This enables us to capture a single cell and measure its physical properties simultaneously. Furthermore, it is shown that short ultrasound pulses at a PRF of 167 kHz can trap and separate either one red blood cell or one prostate cancer cell and facilitate the simultaneous measurement of its integrated backscattering coefficient related to the cell size and mechanical properties.
Journal Article
Mechanogenetics for the remote and noninvasive control of cancer immunotherapy
2018
While cell-based immunotherapy, especially chimeric antigen receptor (CAR)-expressing T cells, is becoming a paradigm-shifting therapeutic approach for cancer treatment, there is a lack of general methods to remotely and noninvasively regulate genetics in live mammalian cells and animals for cancer immunotherapy within confined local tissue space. To address this limitation, we have identified a mechanically sensitive Piezo1 ion channel (mechanosensor) that is activatable by ultrasound stimulation and integrated it with engineered genetic circuits (genetic transducer) in live HEK293T cells to convert the ultrasound-activated Piezo1 into transcriptional activities. We have further engineered the Jurkat T-cell line and primary T cells (peripheral blood mononuclear cells) to remotely sense the ultrasound wave and transduce it into transcriptional activation for the CAR expression to recognize and eradicate target tumor cells. This approach is modular and can be extended for remote-controlled activation of different cell types with high spatiotemporal precision for therapeutic applications.
Journal Article
Considerations for the Effective National CDO Policy: A Comparative Analysis on the Governance of Major Countries
2022
Data is a strategic asset for digital transformation. National innovation based on data has become a matter of global competition and survival. For pursuing a national innovation, it is important that the governance clearly defines the role and responsibility to lead innovation at the national level. In this regard, a national chief data officer (CDO) system has emerged recently as a new paradigm for national data innovation, mainly in the United States, the United Kingdom, and South Korea. This study employs a comparative approach to explaining the trends and common features of the national CDO system. The focal point of analysis is the legal base of CDO system, organization and governance, the required capability and authority of CDO, and its hiring process. Summing up, the study shows that an organization-wide awareness of the benefits of data innovation, a powerful authority to lead and coordinate regarding agencies, and a competent supporting organization are crucial to the successful operation of a CDO system.
Journal Article
Direct and sustained intracellular delivery of exogenous molecules using acoustic-transfection with high frequency ultrasound
2016
Controlling cell functions for research and therapeutic purposes may open new strategies for the treatment of many diseases. An efficient and safe introduction of membrane impermeable molecules into target cells will provide versatile means to modulate cell fate. We introduce a new transfection technique that utilizes high frequency ultrasound without any contrast agents such as microbubbles, bringing a single-cell level targeting and size-dependent intracellular delivery of macromolecules. The transfection apparatus consists of an ultrasonic transducer with the center frequency of over 150 MHz and an epi-fluorescence microscope, entitled acoustic-transfection system. Acoustic pulses, emitted from an ultrasonic transducer, perturb the lipid bilayer of the cell membrane of a targeted single-cell to induce intracellular delivery of exogenous molecules. Simultaneous live cell imaging using HeLa cells to investigate the intracellular concentration of Ca
2+
and propidium iodide (PI) and the delivery of 3 kDa dextran labeled with Alexa 488 were demonstrated. Cytosolic delivery of 3 kDa dextran induced via acoustic-transfection was manifested by diffused fluorescence throughout whole cells. Short-term (6 hr) cell viability test and long-term (40 hr) cell tracking confirmed that the proposed approach has low cell cytotoxicity.
Journal Article
Strategies to shorten turnaround time in outpatient laboratory
2022
Background Turnaround time (TAT) is one of the most important indicators of laboratory quality. For the outpatient routine chemistry tests whose results are checked by clinicians on the same day, we set a quality goal that >90% of these samples should be reported within 60 min. As more than 20% of the samples failed to achieve this goal in 2020, we introduced an additional autoanalyzer and a real‐time monitoring system to improve this rate. Methods As the TAT of the pre‐analytical phase is the greatest contributor to TAT, we divided it into sampling, sample transport, and sample preparation times. An additional autoanalyzer was introduced, and its effect on TAT improvement was evaluated with the TAT data of June and July 2020. A real‐time monitoring system was introduced to sort delayed samples, and its effect was assessed with the TAT data of June and July 2021. TAT data from December 2019 to January 2020 were set as baseline controls. Results The preparation time comprised the largest proportion of TAT. Although there was a slight decrease in overall TAT after the introduction of the above two strategies, the target TAT achievement rate increased significantly from 78.5% to 88.7% (p < 0.001). Conclusions We checked the cause of TAT prolongation and introduced new strategies to improve it. The addition of an autoanalyzer per se was not so effective but was better when combined with the real‐time monitoring system. Such strategies would increase the quality of the laboratory services. To identify the delayed section, we further divided the pre‐analytical phase into three substeps. Among them, preparation time comprised the largest proportion of TAT. As the samples are rushed early in the morning, we devised a real‐time monitoring system to set the test priority of samples based on the time elapsed and assign them to four autoanalyzers considering their workload.
Journal Article
FRET-Based Ca 2+ Biosensor Single Cell Imaging Interrogated by High-Frequency Ultrasound
by
Shung, Kirk
,
Wang, Yingxiao
,
Pan, Yijia
in
Biosensing Techniques
,
Calcium - analysis
,
Cells, Cultured
2020
Fluorescence resonance energy transfer (FRET)-based biosensors have advanced live cell imaging by dynamically visualizing molecular events with high temporal resolution. FRET-based biosensors with spectrally distinct fluorophore pairs provide clear contrast between cells during dual FRET live cell imaging. Here, we have developed a new FRET-based Ca
biosensor using EGFP and FusionRed fluorophores (FRET-GFPRed). Using different filter settings, the developed biosensor can be differentiated from a typical FRET-based Ca
biosensor with ECFP and YPet (YC3.6 FRET Ca
biosensor, FRET-CFPYPet). A high-frequency ultrasound (HFU) with a carrier frequency of 150 MHz can target a subcellular region due to its tight focus smaller than 10 µm. Therefore, HFU offers a new single cell stimulations approach for FRET live cell imaging with precise spatial resolution and repeated stimulation for longitudinal studies. Furthermore, the single cell level intracellular delivery of a desired FRET-based biosensor into target cells using HFU enables us to perform dual FRET imaging of a cell pair. We show that a cell pair is defined by sequential intracellular delivery of the developed FRET-GFPRed and FRET-CFPYPet into two target cells using HFU. We demonstrate that a FRET-GFPRed exhibits consistent 10-15% FRET response under typical ionomycin stimulation as well as under a new stimulation strategy with HFU.
Journal Article
Signal Detection of Point Targets Using Eigen-Images for Super-Resolution Ultrasound Imaging and Gas Vesicle Localization
2025
Accurate signal detection of ultrasound contrast agents, such as microbubble (MB) and gas vesicle (GV), in the presence of clutter and noise is essential to increase image quality in super-resolution ultrasound imaging (SRUS) and achieve precise GV localization. We developed and evaluated an eigen-image based signal detection method using singular value decomposition (SVD) and changepoint detection to automatically segment the data that are closely related to physical events such as MB flow and GV collapse. Eigen-image based method was compared with the elbow point and hard thresholding method when selecting MB signals after SVD of raw data, acquired from phantom and in vivo experiments. Image reconstructed by eigen-image based method was also compared with unregistered difference image for GV localization when moving GVs in a phantom were collapsed by ultrafast plane waves. The eigen-image based MB signal detection method resulted in higher vessel density (VD) visualization in both the phantom and in vivo mouse tumor. It also achieved increased signal-to-noise ratio (SNR) in both cases. Moreover, this method localized moving GVs more efficiently than the difference imaging method, without requiring pixel registration based on landmarks. The eigen-image based method offers a reliable and automated approach to MB and GV signal detection for both SRUS and point target localization. This approach is a valuable tool for medical imaging providing high-quality vessel images along with accurate locations of moving ultrasound contrast agents, which can be potentially translatable to clinical diagnosis and pre-clinical research.
Journal Article