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Magnetic Resonance Imaging: Historical Overview, Technical Developments, and Clinical Applications
Jahng, Geon-Ho,Park, Soonchan,Ryu, Chang-Woo,Cho, Zang-Hee Korean Society of Medical Physics 2020 의학물리 Vol.31 No.3
The authors congratulate the cerebrations for the 30 years of the Korean Society of Medical Physics (http://www.ksmp.or.kr/). The paper is published to recognize the anniversary. Geon-Ho Jahng invited Professor Z. H. Cho to join to submit this manuscript because he has been one of the leaders in the field of magnetic resonance imaging (MRI) during the last 40 years. In this review, we describe the development and clinical histories of MRI internationally and domestically. We also discuss diffusion and perfusion MRI, molecular imaging using MRI and MR spectroscopy (MRS), and the hybrid systems, such as positron emission tomography-MRI (PET-MRI), MR-guided focused ultrasound surgery (MRgFUS), and MRI-guided linear accelerators (MRI-LINACs). In each part, we discuss the historical evolution of the developments, technical developments, and clinical applications.
Jahng, Junghoon,Yang, Heejae,Lee, Eun Seong Nature Publishing Group UK 2018 Light, science & applications Vol.7 No.1
<▼1><P>The opto-mechanical force response from light-illuminated nanoscale materials has been exploited in many tip-based imaging applications to characterize various heterogeneous nanostructures. Such a force can have two origins: thermal expansion and induced dipoles. The thermal expansion reflects the absorption of the material, which enables one to chemically characterize a material at the absorption resonance. The induced dipole interaction reflects the local refractive indices of the material underneath the tip, which is useful to characterize a material in the spectral region where no absorption resonance occurs, as in the infrared (IR)-inactive region. Unfortunately, the dipole force is relatively small, and the contrast is rarely discernible for most organic materials and biomaterials, which only show a small difference in refractive indices for their components. In this letter, we demonstrate that refractive index contrast can be greatly enhanced with the assistance of a functionalized tip. With the enhanced contrast, we can visualize the substructure of heterogeneous biomaterials, such as a polyacrylonitrile-nanocrystalline cellulose (PAN-NCC) nanofiber. From substructural visualization, we address the issue of the tensile strength of PAN-NCC fibers fabricated by several different mixing methods. Our understanding from the present study will open up a new opportunity to provide enhanced sensitivity for substructure mapping of nanobiomaterials, as well as local field mapping of photonic devices, such as surface polaritons on semiconductors, metals and van der Waals materials.</P></▼1><▼2><P><B>Photoinduced force microscopy: Enhanced sensitivity</B></P><P>Contamination of a scientific instrument is usually considered to be an undesirable outcome. However, researchers from Korea and Canada have now discovered that it can actually benefit an imaging technique called photoinduced force microscopy (PiFM). PiFM is a high-resolution scanning technique that is capable of mapping local refractive index contrast of a sample by measuring the light-induced force that arises between the sample and a closely-spaced tip. Junghoon Jang and coworkers from the Korea Research Institute of Standards and Science (KRISS) and the University of British Columbia have now discovered that the presence of a small amount of polydimethylsiloxane (PDMS) contaminant on the tip can serve to functionalize it and significantly increase the strength of the sample-tip interaction. The team has shown that the functionalized tip can map the substructure of nanofibres of a biomaterial called polyacrylonitrile-nanocrystalline cellulose.</P></▼2>
Jahng, Yurngdong,Kim, Jin-Il 영남대학교 약품개발연구소 1994 영남대학교 약품개발연구소 연구업적집 Vol.4 No.-
trans-Ethyl 1, 2, 3, 4a, 5, 6, 8a-octahydro-2-benzyl-4-hydroxy-6-methyl-5-isoquinoline-carboxylate was prepared by intramolecular Diels-Alder reaction as a precursor of newly designed aza-analogue of mevinolin.
Jahng, Junghoon,Potma, Eric O.,Lee, Eun Seong American Chemical Society 2018 ANALYTICAL CHEMISTRY - Vol.90 No.18
<P>We investigate the tip-enhanced thermal expansion force for nanoscale chemical imaging and spectroscopy in the tip-sample junction. It is found, both theoretically and experimentally, that the tip-enhanced absorption of the near-field at the tip followed by sample expansion shows characteristic behaviors with respect to the sample thickness and the incident laser pulse width. The van der Waals interaction plays a major role in exerting a force on the tip from the thermally expanded sample. The force behavior of the photoinduced force microscope (PiFM) is compared with that of the existing photothermal-induced resonance technique (PTIR) to unravel the ambiguous thermal expansion force mechanism. The present study opens up new opportunities for enhancing the performance of optical nanoscopy and spectroscopy such as chemical imaging of nanobiomaterials and the local field mapping of photonic devices, including surface polaritons on van der Waals materials with the assistance of the thermal expansion of a functionalized tip.</P> [FIG OMISSION]</BR>
Jahng, Jaehoon,Youn, Young Hoon,Kim, Kwang Hyun,Yu, Junghwan,Lee, Yong Chan,Hyung, Woo Jin,Noh, Sung Hoon,Kim, Hyunki,Kim, Hogeun,Park, Hyojin,Lee, Sang In WJG Press 2012 World journal of gastroenterology Vol.18 No.27
<P>To investigate endoscopic and clinicopathologic characteristics of early gastric cancer (EGC) according to microsatellite instability phenotype.</P>
Jahng, J.W.,Lee, J.H. North-Holland ; Elsevier Science Ltd 2015 european journal of pharmacology Vol.768 No.-
Intraperitoneal injections (ip) of lithium chloride at large doses induce c-Fos expression in the brain regions implicated in conditioned taste aversion (CTA) learning, and also activate the hypothalamic-pituitary-adrenal (HPA) axis and increase the plasma corticosterone levels in rats. A pharmacologic treatment blunting the lithium-induced c-Fos expression in the brain regions, but not the HPA axis activation, induced CTA formation. Synthetic glucocorticoids at conditioning, but not glucocorticoid antagonist, attenuated the lithium-induced CTA acquisition. The CTA acquisition by ip lithium was not affected by adrenalectomy regardless of basal corticosterone supplement, but the extinction was delayed in the absence of basal corticosterone. Glucocorticoids overloading delayed the extinction memory formation of lithium-induced CTA. ip lithium consistently induced the brain c-Fos expression, the HPA activation and CTA formation regardless of the circadian activation of the HPA axis. Intracerebroventricular (icv) injections of lithium at day time also increased the brain c-Fos expression, activated the HPA axis and induced CTA acquisition. However, icv lithium at night, when the HPA axis shows its circadian activation, did not induce CTA acquisition nor activate the HPA axis, although it increased the brain c-Fos expression. These results suggest that the circadian activation of the HPA axis may affect central, but not peripheral, effect of lithium in CTA learning in rats, and the HPA axis activation may be necessary for the central effect of lithium in CTA formation. Also, glucocorticoids may be required for a better extinction; however, increased glucocorticoids hinder both the acquisition and the extinction of lithium-induced CTA.