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3. Cryogenically-cooled neodymium-doped solid-state lasers

Author

Yoon, Sung Jin and Mackenzie, Jacob

Subjects
621.36
Abstract

The central idea of this thesis is to study cryogenically-cooled neodymium (Nd3+) doped lasers operating on the 4F3/2 → 4I9/2 transition around 0.95 microns, known as a quasi-four-level (QFL) transition. The QFL transition has unavoidable reabsorption loss at room temperature that introduces additional saturable losses into the laser cavity and must be overcome to achieve efficient operation. In general, this particular transition has lower gain than the dominant four-level 4F3/2 → 4I11/2 transition, around 1 micron. While the advantages of cryogenically cooled gain media have been recognised since the birth of the laser, in more recent times there has been a trend in exploiting these advantages for power-scaling QFL lasers, such as Yb-doped gain media. The first part of the thesis explores the extensive characterization of the spectroscopic properties of Nd3+ doped crystals. The present work tracks the spectroscopic changes over the temperature range from 77K to 450K. A number of crystals (YAG, GSAG, YVO4, GdVO4, KGW, YLF) hosting Nd3+ ions have been studied. The absorption cross section spectra for 800nm and 870nm bands were determined with 0.1nm resolution. The absorbance was measured exploiting the Beer-Lambert law and a bespoke set-up using two separate broadband light sources. The fluorescence spectrum was collected and characterized for the transitions to 4I9/2, 4I11/2, and 4I13/2 energy-levels from the metastable level, 4F3/2, from which we calculated the stimulated emission cross section of the various crystals and over the temperature range by applying the Füchtbauer-Ladenburg equation, with the measured fluorescence lifetime. Furthermore, in this report we determine the energy transfer upconversion parameters, for the same set of crystals, using the Z-scan technique. The technique measures the change in transmittance of a probe beam tuned to an absorption peak of crystal sample. The measured transmitted power changes as the intensity incident on the crystal is varied via scanning the beam size and correlated to the saturation intensity through a spatially-dependent rate equation model, we found excellent fit between experiment and simulation. The second part of this thesis reports the development of cryogenic lasers. The design strategies are described by end-pumped and side-pumped systems, with two different crystal geometries reported. Conventional radially-cooled rods are first reported with an end-pumping arrangement, then with a slab (Brewster angled, and afterwards AR coated), and finally a side-pumped Zigzag slab configuration. A rod geometry is tested using a Nd:YAG and a Nd:GSAG crystal for generation of QFL laser emission. The first end-pumped Nd:YAG rod have demonstrated 3.8W at 946nm for 12.8W of pump being absorbed and slope efficiency of 47%. Similar experiment was duplicated with Nd:GSAG rod demonstrating 3.5W at 942nm for 10.5W of pump absorbed. Both suffered significant modal instability during laser oscillation, which afterwards for the Nd:GSAG crystal was found to be due to AR-coating damage. A Nd:YAG slab crystal was tested for the both pumping configurations, using a wavelength-locked 869nm diode bar as a pump source. For this in-band pump-source, the quantum defect is only 8%, in the case of the main QFL transition. A top/bottom-face cooled slab presented effective mitigation of the previously observed modal stability, assumed to be associated with reducing birefringence losses. Despite the coating damage/contamination, which was repeatedly encountered, 946nm emission for both configurations was demonstrated. An end-pumping configuration has demonstrated 5.5W for 13.6W of absorbed pump with 47% slope efficiency. While the side-pumping the zigzag slab produced 6.3W for 30W of absorbed pump with 30% slope efficiency. It is expected that with improvements in the cleanliness within the vacuum chamber used for the cryogenic setup, better results in terms of slope efficiency, output power and beam quality will be realised in the near future.

Published
2016

4. TGF-β and SHH Regulate Pluripotent Stem Cell Differentiation into Brain Microvascular Endothelial Cells in Generating an In Vitro Blood–Brain Barrier Model

Author

Lee, Na Geum, primary, Lim, Mi-Hee, additional, Park, Jongjin, additional, Jeung, In Cheul, additional, Hwang, Byungtae, additional, Lee, Jangwook, additional, Park, Jong-Gil, additional, Son, Mi-Young, additional, Han, Baek Soo, additional, Yoon, Sung-Jin, additional, Lee, Seon-Jin, additional, Park, Young-Jun, additional, Kim, Jae Ho, additional, Lee, Nam-Kyung, additional, Lee, Sang Chul, additional, and Min, Jeong-Ki, additional

Published
2023
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9. Endothelial PTP4A1 mitigates vascular inflammation via USF1/A20 axis-mediated NF-κB inactivation

Author

Cho, Min Ji, primary, Lee, Dong Gwang, additional, Lee, Jeong Woong, additional, Hwang, Byungtae, additional, Yoon, Sung-Jin, additional, Lee, Seon-Jin, additional, Park, Young-Jun, additional, Park, Seung-Ho, additional, Lee, Hee Gu, additional, Kim, Yong-Hoon, additional, Lee, Chul-Ho, additional, Lee, Jangwook, additional, Lee, Nam-Kyung, additional, Han, Tae-Su, additional, Cho, Hyun-Soo, additional, Moon, Jeong Hee, additional, Lee, Ga Seul, additional, Bae, Kwang-Hee, additional, Hwang, Geum-Sook, additional, Lee, Sang-Hak, additional, Chung, Sang J, additional, Shim, Sungbo, additional, Cho, Jaehyung, additional, Oh, Goo Taeg, additional, Kwon, Young-Guen, additional, Park, Jong-Gil, additional, and Min, Jeong-Ki, additional

Published
2022
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13. Endothelial PTP4A1 mitigates vascular inflammation via USF1/A20 axis-mediated NF-κB inactivation.

Author

Cho, Min Ji, Lee, Dong Gwang, Lee, Jeong Woong, Hwang, Byungtae, Yoon, Sung-Jin, Lee, Seon-Jin, Park, Young-Jun, Park, Seung-Ho, Lee, Hee Gu, Kim, Yong-Hoon, Lee, Chul-Ho, Lee, Jangwook, Lee, Nam-Kyung, Han, Tae-Su, Cho, Hyun-Soo, Moon, Jeong Hee, Lee, Ga Seul, Bae, Kwang-Hee, Hwang, Geum-Sook, and Lee, Sang-Hak

Subjects
CELL adhesion molecules, APOLIPOPROTEIN E, PROTEIN-tyrosine phosphatase, SMALL interfering RNA, PHOSPHOPROTEIN phosphatases, KNOCKOUT mice
Abstract

Aims The nuclear factor-κB (NF-κB) signalling pathway plays a critical role in the pathogenesis of multiple vascular diseases. However, in endothelial cells (ECs), the molecular mechanisms responsible for the negative regulation of the NF-κB pathway are poorly understood. In this study, we investigated a novel role for protein tyrosine phosphatase type IVA1 (PTP4A1) in NF-κB signalling in ECs. Methods and results In human tissues, human umbilical artery ECs, and mouse models for loss of function and gain of function of PTP4A1, we conducted histological analysis, immunostaining, laser-captured microdissection assay, lentiviral infection, small interfering RNA transfection, quantitative real-time PCR and reverse transcription-PCR, as well as luciferase reporter gene and chromatin immunoprecipitation assays. Short hairpin RNA-mediated knockdown of PTP4A1 and overexpression of PTP4A1 in ECs indicated that PTP4A1 is critical for inhibiting the expression of cell adhesion molecules (CAMs). PTP4A1 increased the transcriptional activity of upstream stimulatory factor 1 (USF1) by dephosphorylating its S309 residue and subsequently inducing the transcription of tumour necrosis factor-alpha-induced protein 3 (TNFAIP3 / A20) and the inhibition of NF-κB activity. Studies on Ptp4a1 knockout or transgenic mice demonstrated that PTP4A1 potently regulates the interleukin 1β-induced expression of CAMs in vivo. In addition, we verified that PTP4A1 deficiency in apolipoprotein E knockout mice exacerbated high-fat high-cholesterol diet-induced atherogenesis with upregulated expression of CAMs. Conclusion Our data indicate that PTP4A1 is a novel negative regulator of vascular inflammation by inducing USF1/A20 axis-mediated NF-κB inactivation. Therefore, the expression and/or activation of PTP4A1 in ECs might be useful for the treatment of vascular inflammatory diseases. [ABSTRACT FROM AUTHOR]

Published
2023
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14. Decisive Indicator for Gastrointestinal Workup in Anemic Patients with Nondialysis Chronic Kidney Disease

Author

Hyeon Seok Hwang, Youn Mi Song, Eun Oh Kim, Eun Sil Koh, Hye Eun Yoon, Sung Jin Chung, Sang Ju Lee, Yoon Kyung Chang, Chul Woo Yang, Yoon Sik Chang, Suk Young Kim

Subjects
Medicine
Abstract

Background: Anemia and iron deficiency are universal problems in patients with chronic kidney disease (CKD). However, decisive indicator to guide the further gastrointestinal (GI) workup has not been determined.Methods: We included 104 anemic patients with nondialysis-dependent CKD stages 3-5 (38 patients at stage 3, 26 patients at stage 4, and 40 patients at stage 5). Hemoglobin, serum ferritin, transferrin saturation (TSAT), mean corpuscular volume (MCV), and corrected reticulocyte count data were assessed to evaluate diagnostic utility for bleeding-related GI lesions, which were identified by esophagogastroduodenoscopy and colonoscopy.Results: Bleeding-related GI lesions were found in 55 (52.9%) patients, and patients with stage 5 CKD had a higher prevalence of gastric lesions than patients with CKD stage 3 or 4 (all p < 0.05). The areas under the receiver operating characteristic curves used to predict bleeding-related lesions were 0.69 for TSAT (p = 0.002) and 0.61 for serum ferritin (p = 0.085). The sensitivity and specificity of a cutoff value for TSAT < 20% were 0.59 and 0.74, respectively. Hemoglobin, MCV, and corrected reticulocyte levels had no significant diagnostic utility. On multivariable logistic regression, the chance of GI lesions increased by 6% for each 1% reduction in TSAT and increased 4.1-fold for patients with CKD stage 5 (all p < 0.05).Conclusions: TSAT is a useful indicator for determining the GI workup in anemic patients with nondialysis-dependent CKD stages 3-5. Stage 5 CKD is independently associated with bleeding-related lesions and TSAT should be used cautiously in these patients.

Published
2012

17. A novel thermostable arylesterase from the archaeon Sulfolobus solfataricus P1: purification, characterization, and expression

Author

Park, Young-Jun, Yoon, Sung-Jin, and Lee, Hee-Bong

Subjects
Enzymes -- Identification and classification, Sulfur bacteria -- Physiological aspects, Biological sciences
Abstract

A novel thermostable arylesterase, a 35-kDa monomeric enzyme, was purified from the thermoacidophilic archaeon Sulfolobus solfataricus P1. The optimum temperature and pH were 94[degrees]C and 7.0, respectively. The enzyme displayed remarkable thermostability: it retained 52% of its activity after 50 h of incubation at 90[degrees]C. In addition, the purified enzyme showed high stability against denaturing agents, including various detergents, urea, and organic solvents. The enzyme has broad substrate specificity besides showing an arylesterase activity toward aromatic esters: it exhibits not only carboxylesterase activity toward tributyrin and p-nitrophenyl esters containing unsubstituted fatty acids from butyrate ([C.sub.4]) to palmitate ([C.sub.16]), but also paraoxonase activity toward organophosphates such as p-nitrophenylphosphate, paraoxon, and methylparaoxon. The [k.sub.cat]/[K.sub.m] ratios of the enzyme for phenyl acetate and paraoxon, the two most preferable substrates among all tested, were 30.6 and 119.4 [s.sup.-1] x [micro][M.sup.-1], respectively. The arylesterase gene consists of 918 bp corresponding to 306 amino acid residues. The deduced amino acid sequence shares 34% identity with that of arylesterase from Acinetobacter sp. strain ADP1. Furthermore, we successfully expressed active recombinant S. solfataricus arylesterase in Escherichia coli. Together, our results show that the enzyme is a serine esterase belonging to the A-esterases and contains a catalytic triad composed of Ser156, Asp251, and His281 in the active site.

Published
2008

20. Thioredoxin-Interacting Protein Promotes Phagosomal Acidification Upon Exposure to Escherichia coli Through Inflammasome-Mediated Caspase-1 Activation in Macrophages

Author

Yoon, Sung-Jin, primary, Jo, Dong Hyun, additional, Park, Seung-Ho, additional, Park, Jun-Young, additional, Lee, Yoo-Kyung, additional, Lee, Moo-Seung, additional, Min, Jeong-Ki, additional, Jung, Haiyoung, additional, Kim, Tae-Don, additional, Yoon, Suk Ran, additional, Chung, Su Wol, additional, Kim, Jeong Hun, additional, Choi, Inpyo, additional, and Park, Young-Jun, additional

Published
2019
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21. p38 Stabilizes Snail by Suppressing DYRK2-Mediated Phosphorylation That Is Required for GSK3β-βTrCP–Induced Snail Degradation

Author

Ryu, Ki-Jun, primary, Park, Sun-Mi, additional, Park, Seung-Ho, additional, Kim, In-Kyu, additional, Han, Hyeontak, additional, Kim, Hyo-Jin, additional, Kim, Seon-Hee, additional, Hong, Keun-Seok, additional, Kim, Hyemin, additional, Kim, Minju, additional, Yoon, Sung-Jin, additional, Asaithambi, Killivalavan, additional, Lee, Kon Ho, additional, Park, Jae-Yong, additional, Hah, Young-Sool, additional, Cho, Hee Jun, additional, Yook, Jong In, additional, Yang, Jung Wook, additional, Ko, Gyung-Hyuck, additional, Lee, Gyemin, additional, Kang, Yang Jae, additional, Hwangbo, Cheol, additional, Kim, Kwang Dong, additional, Park, Young-Jun, additional, and Yoo, Jiyun, additional

Published
2019
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26. Cryogenically-cooled neodymium-doped solid-state lasers

Author

Yoon, Sung Jin. and Yoon, Sung Jin.

Abstract

The central idea of this thesis is to study cryogenically-cooled neodymium (Nd3+) doped lasers operating on the 4F3/2 → 4I9/2 transition around 0.95 microns, known as a quasi-four-level (QFL) transition. The QFL transition has unavoidable reabsorption loss at room temperature that introduces additional saturable losses into the laser cavity and must be overcome to achieve efficient operation. In general, this particular transition has lower gain than the dominant four-level 4F3/2 → 4I11/2 transition, around 1 micron. While the advantages of cryogenically cooled gain media have been recognised since the birth of the laser, in more recent times there has been a trend in exploiting these advantages for power-scaling QFL lasers, such as Yb-doped gain media. The first part of the thesis explores the extensive characterization of the spectroscopic properties of Nd3+ doped crystals. The present work tracks the spectroscopic changes over the temperature range from 77K to 450K. A number of crystals (YAG, GSAG, YVO4, GdVO4, KGW, YLF) hosting Nd3+ ions have been studied. The absorption cross section spectra for 800nm and 870nm bands were determined with 0.1nm resolution. The absorbance was measured exploiting the Beer-Lambert law and a bespoke set-up using two separate broadband light sources. The fluorescence spectrum was collected and characterized for the transitions to 4I9/2, 4I11/2, and 4I13/2 energy-levels from the metastable level, 4F3/2, from which we calculated the stimulated emission cross section of the various crystals and over the temperature range by applying the Füchtbauer-Ladenburg equation, with the measured fluorescence lifetime. Furthermore, in this report we determine the energy transfer upconversion parameters, for the same set of cryst

Published
2016

29. TXNIP Deficiency Exacerbates Endotoxic Shock via the Induction of Excessive Nitric Oxide Synthesis

Author

Park, Young-Jun, primary, Yoon, Sung-Jin, additional, Suh, Hyun-Woo, additional, Kim, Dong Oh, additional, Park, Jeong-Ran, additional, Jung, Haiyoung, additional, Kim, Tae-Don, additional, Yoon, Suk Ran, additional, Min, Jeong-Ki, additional, Na, Hee-Jun, additional, Lee, Seon-Jin, additional, Lee, Hee Gu, additional, Lee, Young Ho, additional, Lee, Hee-Bong, additional, and Choi, Inpyo, additional

Published
2013
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36. B2-05: Frontline cytotoxic chemotherapy (CTx) for newly diagnosed non-small cell lung cancer (NSCLC) patients presenting with brain metastasis compared to whole brain radiotherapy (WBRT): Result of a randomized pilot study

Author

Lee, Dae Ho, primary, Han, Ji-Youn, additional, Kim, Heung Tae, additional, Pyo, Hong Ryull, additional, Cho, Kwan Ho, additional, Shin, Sang-Hoon, additional, Yoo, Heon, additional, Lee, Seung-Hoon, additional, Yoon, Sung Jin, additional, and Lee, Jin Soo, additional

Published
2007
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39. Laparoscopic Hiatal Hernia Repair and Roux-en-Y Conversion for Refractory Duodenogastroesophageal Reflux after Billroth I Distal Gastrectomy.

Author

Park JM, Yoon SJ, Kim JW, and Chi KC

Abstract

Distal gastrectomy with Billroth I or II reconstruction may cause duodenogastroesophageal reflux (DGER), thereby resulting in digestive or respiratory symptoms. The mainstay of treatment is medication with proton pump inhibitors. However, these drugs may have limited effects in DGER. Laparoscopic fundoplication has been proven to be highly effective in treating gastroesophageal reflux disease (GERD), but it cannot be performed optimally for GERD that develops after gastrectomy. We report the case of a 72-year-old man with a history of distal gastrectomy and Billroth I anastomosis due to early gastric cancer. GERD due to bile reflux occurred after surgery and was refractory to medical therapy. The patient underwent Roux-en-Y conversion from Billroth I gastroduodenostomy and hiatal hernia repair with only cruroplasty. Fundoplication was not performed. His symptoms improved significantly after the surgery. Therefore, laparoscopic hiatal hernia repair and Roux-en-Y conversion can be an effective surgical procedure to treat medically refractory DGER after Billroth I gastrectomy., Competing Interests: Conflict of Interest: No potential conflict of interest relevant to this article was reported., (Copyright © 2020. Korean Gastric Cancer Association.)

Published
2020
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