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Chen WJ, Pozdeev AS, Choi HW, Boldyrev AI, Yuan DF, Popov IA, Wang LS. Searching for stable copper borozene complexes in CuB 7- and CuB 8. Phys Chem Chem Phys 2024. [PMID: 38456623 DOI: 10.1039/d4cp00296b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2024]
Abstract
Copper has been shown to be an important substrate for the growth of borophenes. Copper-boron binary clusters are ideal platforms to study the interactions between copper and boron, which may provide insight about the underlying growth mechanisms of borophene on copper substrates. Here we report a joint photoelectron spectroscopy and theoretical study on two copper-doped boron clusters, CuB7- and CuB8-. Well resolved photoelectron spectra are obtained for the two clusters at different wavelengths and are used to understand the structures and bonding properties of the two CuBn- clusters. We find that CuB8- is a highly stable borozene complex, which possesses a half-sandwich structure with a Cu+ species interacting with the doubly aromatic η8-B82- borozene. The CuB7- cluster is found to consist of a terminal copper atom bonded to a double-chain B7 motif, but it has a low-lying isomer composed of a half-sandwich structure with a Cu+ species interacting with an open-shell η7-B72- borozene. Both ionic and covalent interactions are found to be possible in the binary Cu-B clusters, resulting in different structures.
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Affiliation(s)
- Wei-Jia Chen
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA.
| | - Anton S Pozdeev
- Department of Chemistry, The University of Akron, Akron, Ohio 44325, USA.
| | - Hyun Wook Choi
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA.
| | - Alexander I Boldyrev
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA
| | - Dao-Fu Yuan
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA.
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China.
| | - Ivan A Popov
- Department of Chemistry, The University of Akron, Akron, Ohio 44325, USA.
| | - Lai-Sheng Wang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA.
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Gao HW, Choi HW, Hui J, Chen WJ, Kocheril GS, Wang LS. On the electronic structure and spin-orbit coupling of BiB from photoelectron imaging of cryogenically-cooled BiB- anion. J Chem Phys 2023; 159:114301. [PMID: 37712786 DOI: 10.1063/5.0170325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 08/28/2023] [Indexed: 09/16/2023] Open
Abstract
We report a study on the electronic structure and chemical bonding of the BiB molecule using high-resolution photoelectron imaging of cryogenically cooled BiB- anion. By eliminating all the vibrational hot bands, we can resolve the complicated detachment transitions due to the open-shell nature of BiB and the strong spin-orbit coupling. The electron affinity of BiB is measured to be 2.010(1) eV. The ground state of BiB- is determined to be 2Π(3/2) with a σ2π3 valence electron configuration, while the ground state of BiB is found to be 3Σ-(0+) with a σ2π2 electron configuration. Eight low-lying spin-orbit excited states [3Σ-(1), 1Δ(2), 1Σ+(0+), 3Π(2), 3Π(1), 1Π(1)], including two forbidden transitions, [3Π(0-) and 3Π(0+)], are observed for BiB as a result of electron detachment from the σ and π orbitals of BiB-. The angular distribution information from the photoelectron imaging is found to be critical to distinguish detachment transitions from the σ or π orbital for the spectral assignment. This study provides a wealth of information about the low-lying electronic states and spin-orbit coupling of BiB, demonstrating the importance of cryogenic cooling for obtaining well-resolved photoelectron spectra for size-selected clusters produced from a laser vaporization cluster source.
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Affiliation(s)
- Han-Wen Gao
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
| | - Hyun Wook Choi
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
| | - Jie Hui
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
| | - Wei-Jia Chen
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
| | - G Stephen Kocheril
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
| | - Lai-Sheng Wang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
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Pozdeev AS, Chen WJ, Choi HW, Kulichenko M, Yuan DF, Boldyrev AI, Wang LS. Photoelectron Spectroscopy and Theoretical Study of Di-Copper-Boron Clusters: Cu 2B 3- and Cu 2B 4. J Phys Chem A 2023. [PMID: 37235389 DOI: 10.1021/acs.jpca.3c02417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Copper has been found to be able to mediate the formation of bilayer borophenes. Copper-boron binary clusters are ideal model systems to probe the copper-boron interactions, which are essential to understand the growth mechanisms of borophenes on copper substrates. Here, we report a joint photoelectron spectroscopy and theoretical study on two di-copper-doped boron clusters: Cu2B3- and Cu2B4-. Well-resolved photoelectron spectra are obtained, revealing the presence of a low-lying isomer in both cases. Theoretical calculations show that the global minimum of Cu2B3- (C2v, 1A1) contains a doubly aromatic B3- unit weakly interacting with a Cu2 dimer, while the low-lying isomer (C2v, 1A1) consists of a B3 triangle with the two Cu atoms covalently bonded to two B atoms at two vertexes. The global minimum of Cu2B4- (D2h, 2Ag) is found to consist of a rhombus B4 unit covalently bonded to the two Cu atoms at two opposite vertexes, whereas in the low-lying isomer (Cs, 2A'), one of the two Cu atoms is bonded to two B atoms.
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Affiliation(s)
- Anton S Pozdeev
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, United States
| | - Wei-Jia Chen
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Hyun Wook Choi
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Maksim Kulichenko
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Dao-Fu Yuan
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Alexander I Boldyrev
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, United States
| | - Lai-Sheng Wang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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Ma X, Cheung YF, Lyu H, Choi HW. Heterogeneous integration of a GaN-based photonic integrated circuit with an Si-based transimpedance amplifier. Opt Lett 2023; 48:1124-1127. [PMID: 36857229 DOI: 10.1364/ol.481935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 01/23/2023] [Indexed: 06/18/2023]
Abstract
The heterogeneous integration of a GaN-based photonic integrated circuit (PIC) and an Si-based transimpedance amplifier (TIA) is demonstrated in this work. The monolithic GaN PIC, fabricated from a GaN-on-Si light-emitting diode (LED) wafer, comprises LEDs whose optical outputs are coupled to photodetectors (PD) through suspended waveguides. The PIC chip is mounted onto a printed circuit board together with a TIA chip and two filter chip capacitors, occupying a compact footprint. The components are interconnected directly using wire-bonds to minimize signal delays and attenuation. The integrated system achieves rise and fall times of 2.21 and 2.10 ns, respectively, a transmission delay of 3.54 ns, and a bandwidth exceeding 390 MHz. Transmission of a pseudorandom binary sequence-3 (PRBS-3) signal across the integrated system is also demonstrated at the data transmission rate of 280 Mbit/s with a clearly resolved open eye diagram.
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Jeong BG, Choi HW, Song JK, Park SM. Branching ratio in photodissociation of 1-bromo-3-chlorobenzene cation. Spectrochim Acta A Mol Biomol Spectrosc 2022; 271:120899. [PMID: 35104740 DOI: 10.1016/j.saa.2022.120899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 01/06/2022] [Accepted: 01/12/2022] [Indexed: 06/14/2023]
Abstract
A new and convenient calculation method based on Rice-Ramsperger-Kassel-Marcus (RRKM) theory assuming an extremely loose transition state (LTS) has been attempted to predict the branching ratio in photodissociation. This method enables estimation of the branching ratios without detailed structural information on the transition state which is indispensable in conventional RRKM calculations. To evaluate our simple method through comparison to the experimental results, photodissociation of 1-bromo-3-chlorobenzene cation (3BCB+) was chosen as a model unimolecular reaction system which has two distinct photodissociation channels in ultraviolet region: 3BCB+ → Br-dissociated daughter ion (ClBz+) + Br and 3BCB+ → Cl-dissociated daughter ion (BrBz+) + Cl. The branching ratio was monitored with decreasing the internal energy using a linear tandem time-of-flight mass spectrometer, which clearly showed decreased branching ratios of 3BCB+ → ClBz+ + Br over 3BCB+ → BrBz+ + Cl in reasonable agreement with the calculation results employing the new method. Although there was some discrepancy in internal energy between the experimental and calculation results, the new calculation method is worth to be extended to other diverse systems considering its intuitive and simple nature.
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Affiliation(s)
- Bong Gyu Jeong
- Department of Chemistry, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Hyun Wook Choi
- Department of Chemistry, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Jae Kyu Song
- Department of Chemistry, Kyung Hee University, Seoul 02447, Republic of Korea.
| | - Seung Min Park
- Department of Chemistry, Kyung Hee University, Seoul 02447, Republic of Korea.
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Abstract
Photoelectron spectroscopy and quantum chemistry studies are used to investigate the structure and bonding of AuB8-. Global minimum sturctural searches show that AuB8- possesses a chair-like structure, which can be viewed as Au+ bonded to the edge of the doubly-aromatic B82- borozene, Au+[η2-B82-]. Chemical bonding analyses reveal that the AuB8- is a novel borozene complex with unique Au-borozene bonding.
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Affiliation(s)
- Wei-Jia Chen
- Department of Chemistry, Brown University, Providence, RI 02912, USA.
| | - Yang-Yang Zhang
- Department of Chemistry and Key Laboratory of Organic Optoelectronics & Molecular Engineering of Ministry of Education, Tsinghua University, Beijing 100084, China.
| | - Wan-Lu Li
- Department of Chemistry and Key Laboratory of Organic Optoelectronics & Molecular Engineering of Ministry of Education, Tsinghua University, Beijing 100084, China.
| | - Hyun Wook Choi
- Department of Chemistry, Brown University, Providence, RI 02912, USA.
| | - Jun Li
- Department of Chemistry and Key Laboratory of Organic Optoelectronics & Molecular Engineering of Ministry of Education, Tsinghua University, Beijing 100084, China. .,Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, China
| | - Lai-Sheng Wang
- Department of Chemistry, Brown University, Providence, RI 02912, USA.
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7
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Chen WJ, Kulichenko M, Choi HW, Cavanagh J, Yuan DF, Boldyrev AI, Wang LS. Photoelectron Spectroscopy of Size-Selected Bismuth-Boron Clusters: BiB n- ( n = 6-8). J Phys Chem A 2021; 125:6751-6760. [PMID: 34333984 DOI: 10.1021/acs.jpca.1c05846] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Because of its low toxicity, bismuth is considered to be a "green metal" and has received increasing attention in chemistry and materials science. To understand the chemical bonding of bismuth, here we report a joint experimental and theoretical study on a series of bismuth-doped boron clusters, BiBn- (n = 6-8). Well-resolved photoelectron spectra are obtained and are used to understand the structures and bonding of BiBn- in conjunction with theoretical calculations. Global minimum searches find that all three BiBn- clusters have planar structures with the Bi atom bonded to the edge of the planar Bn moiety via two Bi-B σ bonds as well as π bonding by the 6pz orbital. BiB6- is found to consist of a double-chain B6 with a terminal Bi atom. Both BiB7- and BiB8- are composed of a Bi atom bonded to the planar global minima of the B7- and B8- clusters. Chemical bonding analyses reveal that BiB6- is doubly antiaromatic, whereas BiB7- and BiB8- are doubly aromatic. In the neutral BiBn (n = 6-8) clusters, except BiB6 which has a planar structure similar to the anion, the global minima of both BiB7 and BiB8 are found to be half-sandwich-type structures due to the high stability of the doubly aromatic B73- and B82- molecular wheel ligands.
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Affiliation(s)
- Wei-Jia Chen
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Maksim Kulichenko
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, United States
| | - Hyun Wook Choi
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Joseph Cavanagh
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Dao-Fu Yuan
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Alexander I Boldyrev
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, United States
| | - Lai-Sheng Wang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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Zi H, Fu WY, Tabataba-Vakili F, Kim-Chauveau H, Frayssinet E, De Mierry P, Damilano B, Duboz JY, Boucaud P, Semond F, Choi HW. Whispering-gallery mode InGaN microdisks on GaN substrates. Opt Express 2021; 29:21280-21289. [PMID: 34265918 DOI: 10.1364/oe.427727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 06/08/2021] [Indexed: 06/13/2023]
Abstract
Microdisks fabricated with III-nitride materials grown on GaN substrates are demonstrated, taking advantage of the high material quality of homoepitaxial films and advanced micro-fabrication processes. The epitaxial structure consists of InGaN/GaN multi-quantum wells (MQWs) sandwiched between AlGaN/GaN and InAlN/GaN superlattices as cladding layers for optical confinement. Due to lattice-matched growth with low dislocations, an internal quantum efficiency of ∼40% is attained, while the sidewalls of the etched 8 µm-diameter microdisks patterned by microsphere lithography are optically smooth to promote the formation of whispering-gallery modes (WGMs) within the circular optical cavities. Optically pumped lasing with low threshold of ∼5.2 mJ/cm2 and quality (Q) factor of ∼3000 at the dominant lasing wavelength of 436.8 nm has been observed. The microdisks also support electroluminescent operation, demonstrating WGMs consistent with the photoluminescence spectra and with finite-difference time-domain (FDTD) simulations.
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9
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Sock Hwee T, Koh HWL, Chua JY, Yang XX, Ong CC, Teo L, Choi HW, Pilbrow AP, Pickering JW, Troughton RW, Doughty RN, Richards AM, Chan MY. P5719Plasma proteomics identify plaque-related proteins that predict long-term recurrent coronary events in patients with acute coronary syndrome. Eur Heart J 2019. [DOI: 10.1093/eurheartj/ehz746.0660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Background
Coronary plaque burden and composition drive recurrent ischaemic events in coronary artery disease.
Purpose
We first investigated the association between plasma proteins and coronary plaque characteristics in a cohort of asymptomatic individuals with low-intermediate Framingham Risk Score. Plaque-related proteins were further evaluated in a second cohort of patients with acute coronary syndrome (ACS) to determine their prognostic value for predicting future myocardial infarction (MI).
Methods
We profiled 1305 plasma proteins using an aptamer-based array (SOMAscan) in asymptomatic individuals who had undergone 384-slice coronary computed tomography angiography. Plaques were categorized by composition as calcified or non-calcified. First, we identified proteins that were different (based on multiple testing adjusted p-values: q-value <0.05) between 250 ACS patients who suffered a recurrent MI event on follow-up compared with another 250 ACS patients who remained event-free using Mann-Whitney U test. Next, protein candidates that also correlated (Pearson's p<0.05) with specific categories of plaque composition were evaluated using a cox proportional hazards model to determine the risk of recurrent MI, adjusting for potential confounders in the second cohort.
Results
A total of 65 and 120 plasma proteins were significantly associated with calcified and non-calcified plaques respectively in the asymptomatic cohort (N=79). Of these 185 proteins, 23 proteins were differentially expressed (DE) between ACS patients with and without recurrent MI events (median follow-up 1811 days). The top three up-and down-regulated proteins in the recurrent MI group were macrophage-capping protein, trefoil factor 3 and cystatin-SN (median FC 1.22, 1.17 and 1.17; q-value 4.34x10–6, 2.18x10–4, 3.17x10–3 respectively) and fibroblast growth factor 20, lymphotoxin a2/b1 and vascular endothelial growth factor receptor 2 (median FC 0.92, 0.94 and −0.090; q-value 1.31x10–3, 9.45x10–3 and 3.90x10–3) respectively. The quartiles of these protein concentrations were also associated with risk of recurrent MI, (log-rank test p-value range from 2.71x10–7 to 0.04). Of the DE proteins, the adjusted hazards ratio (HR) of cystatin-SN in the highest quartile (Q4) was 1.44 times that of the first quartile (Q1) (adjusted HR: 1.44, 95% CI: 0.93–2.2) and higher plasma concentration of cystatin-SN was associated with increasing risk of recurrent MI events (Trend test p=0.004). On the other hand, the highest quartile of fibroblast growth factor 20 was associated with 44% reduction in risks of recurrent MI adjusted HR: 0.56, 95% CI of HR: 0.35–0.87), with significant trend test (p=0.0096).
Conclusions
Large-scale plasma proteomics identified novel plaque-related proteins predictive of recurrent coronary events in patients with ACS. Further studies may help unravel the biological underpinnings of these circulating proteins and their potential as novel prognostic biomarkers.
Acknowledgement/Funding
This work was supported by grant NMRC/CSA-INV/0001/2016 from the National Medical Research Council, Singapore.
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Affiliation(s)
- T Sock Hwee
- National University of Singapore, Singapore, Singapore
| | - H W L Koh
- National University of Singapore, Singapore, Singapore
| | - J Y Chua
- National University Heart Centre, Singapore, Singapore
| | - X X Yang
- National University of Singapore, Singapore, Singapore
| | - C C Ong
- National University Heart Centre, Singapore, Singapore
| | - L Teo
- National University Heart Centre, Singapore, Singapore
| | - H W Choi
- National University of Singapore, Singapore, Singapore
| | - A P Pilbrow
- University of Otago Christchurch, Christchurch, New Zealand
| | - J W Pickering
- University of Otago Christchurch, Christchurch, New Zealand
| | - R W Troughton
- University of Otago Christchurch, Christchurch, New Zealand
| | - R N Doughty
- The University of Auckland, Department of Medicine, Auckland, New Zealand
| | - A M Richards
- National University of Singapore, Singapore, Singapore
| | - M Y Chan
- National University of Singapore, Singapore, Singapore
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Choi HW, Kim KK, Jeong BG, Song JK, Park SM. Structures and infrared photodissociation of [(aniline)-(methanol)-(water) 2] . Spectrochim Acta A Mol Biomol Spectrosc 2019; 220:117119. [PMID: 31141781 DOI: 10.1016/j.saa.2019.05.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 04/30/2019] [Accepted: 05/10/2019] [Indexed: 06/09/2023]
Abstract
The structures of [(aniline)-(methanol)-(water)2]+ were investigated by infrared spectroscopy coupled with linear tandem mass spectrometry. We suggest the most stable structure of [(aniline)-(methanol)-(water)2]+ through infrared photodissociation spectra supported by the density functional theory calculations at the level of ωB97X-D/cc-pVQZ. Methanol and one water molecule formed hydrogen bonding with the amino group of aniline, while the other water formed hydrogen bonding with methanol. Upon infrared excitation of [(aniline)-(methanol)-(water)2]+, the water molecule connected to methanol turned out to be preferentially ejected, although the total internal energy in the cluster ion was large enough to dissociate other solvent molecules. This unique dissociation feature was attributed to the significant difference in the dissociation rates as obtained by the Rice-Ramsperger-Kassel-Marcus theory calculations as well as structural restriction.
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Affiliation(s)
- Hyun Wook Choi
- Department of Chemistry, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Kuk Ki Kim
- Department of Chemistry, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Bong Gyu Jeong
- Department of Chemistry, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Jae Kyu Song
- Department of Chemistry, Kyung Hee University, Seoul 02447, Republic of Korea.
| | - Seung Min Park
- Department of Chemistry, Kyung Hee University, Seoul 02447, Republic of Korea.
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Affiliation(s)
- Hee Ryong Lee
- Department of Nephrology, Maryknoll Hospital, Busan, Korea
| | - Jung Myung An
- Department of Nephrology, Maryknoll Hospital, Busan, Korea
| | - Dong Ryeol Lee
- Department of Nephrology, Maryknoll Hospital, Busan, Korea
| | - Hyun Wook Choi
- Department of Radiology, Maryknoll Hospital, Busan, Korea
| | - Joon Seok Oh
- Department of Nephrology, Bongseng Memorial Hospital, Busan, Korea
| | - Joong Kyung Kim
- Department of Nephrology, Bongseng Memorial Hospital, Busan, Korea
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12
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Kim BH, Park HU, Park SK, Jeon SM, Jung CW, Son CM, Choi HW, Kim HS. [Anisakiasis Induced Segmental Jejunum Obstruction]. Korean J Gastroenterol 2018; 72:33-36. [PMID: 30049176 DOI: 10.4166/kjg.2018.72.1.33] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Human anisakiasis is a disease caused by an infestation of the third stage larvae of family anisakidae. The ingested larvae invade the gastrointestinal wall, causing clinical symptoms that include abdomen pain, nausea, and vomiting. Although enteric anisakiasis is extremely rare, it can induce intestinal obstruction. We report a case in which emergency surgery was needed due to intestinal obstruction that coincided with symptoms related to anisakiasis, along with a brief literature review.
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Affiliation(s)
- Beom Hee Kim
- Department of Internal Medicine, Maryknoll Hospital, Busan, Korea
| | - Hee Ug Park
- Department of Internal Medicine, Maryknoll Hospital, Busan, Korea
| | - Seung Keun Park
- Department of Internal Medicine, Maryknoll Hospital, Busan, Korea
| | - Soung Min Jeon
- Department of Internal Medicine, Maryknoll Hospital, Busan, Korea
| | - Chan Woo Jung
- Department of Internal Medicine, Maryknoll Hospital, Busan, Korea
| | - Chang Mok Son
- Department of General surgery, Maryknoll Hospital, Busan, Korea
| | - Hyun Wook Choi
- Department of Radiology, Maryknoll Hospital, Busan, Korea
| | - Hye Sook Kim
- Department of Pathology, Maryknoll Hospital, Busan, Korea
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Park Y, Li KH, Fu WY, Cheung YF, Choi HW. Packaging of InGaN stripe-shaped light-emitting diodes. Appl Opt 2018; 57:2452-2458. [PMID: 29714220 DOI: 10.1364/ao.57.002452] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 02/26/2018] [Indexed: 06/08/2023]
Abstract
We demonstrate the fabrication of InGaN/GaN stripe-shaped light-emitting diodes (LEDs) in flip-chip packaging (FC-LED) and vertically mounted packaging (VM-LED). Compared to conventionally packaged LEDs, these packaging schemes enhance light output and emission divergence in ways favorable for general lighting applications. The FC-LED can sustain efficiency at high current operations due to effective heat sinking, while the VM-LED excels at light extraction efficiency due to the exposure of two large emission surfaces. Together with the properties of low luminous exitance and emission uniformity, the stripe-shaped LEDs are ideal for the assembly of luminaires. An LED light tube comprising a continuous linear array of 10 stripe-shaped LED chips has been assembled. The optical performance of the light tube is compared to another light tube assembled with conventional square-shaped LED chips (with and without external diffuser) by confocal microscopy. It is found that emission uniformity of the stripe-shaped LED tube is significantly improved, with a threefold increase in illumination area, without efficiency loss associated with diffusers.
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14
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Park YS, Lee SH, Lim CK, Choi HW, An JH, Park CW, Lee HS, Lee JS, Seo JT. Paternal age as an independent factor does not affect embryo quality and pregnancy outcomes of testicular sperm extraction-intracytoplasmic sperm injection in azoospermia. Andrologia 2017; 50. [PMID: 28703337 DOI: 10.1111/and.12864] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/27/2017] [Indexed: 12/25/2022] Open
Abstract
This study was performed to evaluate the independent influence of paternal age affecting embryo development and pregnancy using testicular sperm extraction (TESE)-intracytoplasmic sperm injection (ICSI) in obstructive azoospermia (OA) and nonobstructive azoospermia (NOA). Paternal patients were divided into the following groups: ≤30 years, 31-35 years, 36-40 years, 41-45 years and ≥46 years. There were no differences in the rates of fertilisation or embryo quality according to paternal and maternal age. However, clinical pregnancy and implantation rates were significantly lower between those ≥46 years of paternal age compared with other age groups. Fertilisation rate was higher in the OA than the NOA, while embryo quality, pregnancy and delivery results were similar. Clinical pregnancy and implantation rates were significantly lower for patients ≥46 years of paternal age compared with younger age groups. In conclusion, fertilisation using TESE in azoospermia was not affected by the independent influence of paternal age; however, as maternal age increased concomitantly with paternal age, rates of pregnancy and delivery differed between those with paternal age <41 years and ≥46 years. Therefore, paternal age ≥46 years old should be considered when applying TESE-ICSI in cases of azoospermia, and patients should be advised of the associated low pregnancy rates.
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Affiliation(s)
- Y S Park
- Laboratory of Reproductive Medicine, Cheil General Hospital & Women's Healthcare Center, Dankook University College of Medicine, Seoul, Korea
| | - S H Lee
- Laboratory of Reproductive Medicine, Cheil General Hospital & Women's Healthcare Center, Dankook University College of Medicine, Seoul, Korea.,Division of Developmental Biology and Physiology, School of Biosciences and Chemistry, Sungshin Women's University, Seoul, Korea
| | - C K Lim
- Laboratory of Reproductive Medicine, Cheil General Hospital & Women's Healthcare Center, Dankook University College of Medicine, Seoul, Korea
| | - H W Choi
- Laboratory of Reproductive Medicine, Cheil General Hospital & Women's Healthcare Center, Dankook University College of Medicine, Seoul, Korea
| | - J H An
- Laboratory of Reproductive Medicine, Cheil General Hospital & Women's Healthcare Center, Dankook University College of Medicine, Seoul, Korea
| | - C W Park
- Department of Obstetrics and Gynecology, Cheil General Hospital & Women's Healthcare Center, Dankook University College of Medicine, Seoul, Korea
| | - H S Lee
- Department of Urology, Cheil General Hospital & Women's Healthcare Center, Dankook University College of Medicine, Seoul, Korea
| | - J S Lee
- Department of Urology, Cheil General Hospital & Women's Healthcare Center, Dankook University College of Medicine, Seoul, Korea
| | - J T Seo
- Department of Urology, Cheil General Hospital & Women's Healthcare Center, Dankook University College of Medicine, Seoul, Korea
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15
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Bachus KJ, Mats L, Choi HW, Gibson GTT, Oleschuk RD. Fabrication of Patterned Superhydrophobic/Hydrophilic Substrates by Laser Micromachining for Small Volume Deposition and Droplet-Based Fluorescence. ACS Appl Mater Interfaces 2017; 9:7629-7636. [PMID: 28169515 DOI: 10.1021/acsami.6b16363] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The deposition of nanoliter and subnanoliter volumes is important in chemical and biochemical droplet-based microfluidic systems. There are several techniques that have been established for the deposition/generation of small volumes including the use of surfaces with patterned differences in wettability. Many such methods require complex and time-consuming lithographic techniques. Here, we present a facile method for the fabrication of superhydrophobic surfaces with patterned hydrophilic regions by laser micromachining. A comprehensive study of fabrication parameters (laser machining speed, laser power, and patch size) on the material, patch wettability, and droplet volume is presented. Patch sizes as small as 100 μm diameter and as large as 1500 μm diameter were investigated, and volumes as low as 400 pL were observed. As an example application of such patterned materials and the deposition of small volumes, halide salts were preconcentrated on the hydrophilic patches, and their fluorescence quenching constants were rapidly calculated using a 3D-printed device coupled to a fluorescence spectrometer.
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Affiliation(s)
- K J Bachus
- Department of Chemistry, Queen's University , Kingston, Ontario K7L 3N6, Canada
| | - L Mats
- Department of Chemistry, Queen's University , Kingston, Ontario K7L 3N6, Canada
| | - H W Choi
- Department of Chemistry, Queen's University , Kingston, Ontario K7L 3N6, Canada
| | - G T T Gibson
- CMC Microsystems , Innovation Park, Kingston, Ontario K7L 0E9, Canada
| | - R D Oleschuk
- Department of Chemistry, Queen's University , Kingston, Ontario K7L 3N6, Canada
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16
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Abstract
The majority of a GaN light-emitting diode (LED) is released from its sapphire substrate through selective-area laser lift-off to form a freely suspended light emitter. By virtue of being suspended in air without supporting substrates, the ultrathin crystalline and crack-free film possesses flexibility and bendability. The free-standing LEDs benefit from significant relaxation of strain, evident from red-shifting of the E2(high) phonon frequencies as measured by Raman spectroscopy toward those of strain-free free-standing GaN substrates. The phonon frequencies remain invariant upon bending of the film; this indicates that the properties of the flexible device will not be dependent on the bending curvatures. The observation of pronounced spectral blue-shifts from the photoluminescence (PL) spectrum from the flexible regions further confirms the occurrence of strain relaxation in the quantum wells. Being free-standing and thus lacking a direct heat-sinking pathway, emissions from the different regions of the suspended film can be affected by thermal effects to different extents, which are investigated by long-wave infrared thermometry. Heat accumulation is determined to be most severe at the far end of the flexible stripe at higher currents, leading to reduced efficiencies and electroluminescence (EL) spectral red-shifts. Based on this architecture, a monolithic 3 × 4 dot-matrix microdisplay prototype is demonstrated, comprising three adjacent flexible stripe emitters with four individually addressable pixels on each stripe. This proof-of-concept demonstration opens up new opportunities for GaN optoelectronics for a wide range of flexible display and visual applications.
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Affiliation(s)
- Y F Cheung
- Department of Electrical and Electronic Engineering, The University of Hong Kong , Pokfulam Road, Hong Kong
| | - K H Li
- Department of Electrical and Electronic Engineering, The University of Hong Kong , Pokfulam Road, Hong Kong
| | - H W Choi
- Department of Electrical and Electronic Engineering, The University of Hong Kong , Pokfulam Road, Hong Kong
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17
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Stebbings KA, Choi HW, Ravindra A, Caspary DM, Turner JG, Llano DA. Ageing-related changes in GABAergic inhibition in mouse auditory cortex, measured using in vitro flavoprotein autofluorescence imaging. J Physiol 2015; 594:207-21. [PMID: 26503482 DOI: 10.1113/jp271221] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Accepted: 10/18/2015] [Indexed: 12/24/2022] Open
Abstract
KEY POINTS Ageing is associated with hearing loss and changes in GABAergic signalling in the auditory system. We tested whether GABAergic signalling in an isolated forebrain preparation also showed ageing-related changes. A novel approach was used, whereby population imaging was coupled to quantitative pharmacological sensitivity. Sensitivity to GABAA blockade was inversely associated with age and cortical thickness, but hearing loss did not independently contribute to the change in GABAA ergic sensitivity. Redox states in the auditory cortex of young and aged animals were similar, suggesting that the differences in GABAA ergic sensitivity are unlikely to be due to differences in slice health. To examine ageing-related changes in the earliest stages of auditory cortical processing, population auditory cortical responses to thalamic afferent stimulation were studied in brain slices obtained from young and aged CBA/CAj mice (up to 28 months of age). Cortical responses were measured using flavoprotein autofluorescence imaging, and ageing-related changes in inhibition were assessed by measuring the sensitivity of these responses to blockade of GABAA receptors using bath-applied SR95531. The maximum auditory cortical response to afferent stimulation was not different between young and aged animals under control conditions, but responses to afferent stimulation in aged animals showed a significantly lower sensitivity to GABA blockade with SR95531. Cortical thickness, but not hearing loss, improved the prediction of all imaging variables when combined with age, particularly sensitivity to GABA blockade for the maximum response. To determine if the observed differences between slices from young and aged animals were due to differences in slice health, the redox state in the auditory cortex was assessed by measuring the FAD+/NADH ratio using fluorescence imaging. We found that this ratio is highly sensitive to known redox stressors such as H2 O2 and NaCN; however, no difference was found between young and aged animals. By using a new approach to quantitatively assess pharmacological sensitivity of population-level cortical responses to afferent stimulation, these data demonstrate that auditory cortical inhibition diminishes with ageing. Furthermore, these data establish a significant relationship between cortical thickness and GABAergic sensitivity, which had not previously been observed in an animal model of ageing.
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Affiliation(s)
- K A Stebbings
- Neuroscience Program, University of Illinois at Urbana-Champaign, IL, USA
| | - H W Choi
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, IL, USA
| | - A Ravindra
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, IL, USA
| | - D M Caspary
- Department of Pharmacology, Southern Illinois University College of Medicine, IL, USA
| | - J G Turner
- Department of Pharmacology, Southern Illinois University College of Medicine, IL, USA.,Department of Psychology, Illinois College, IL, USA
| | - D A Llano
- Neuroscience Program, University of Illinois at Urbana-Champaign, IL, USA.,Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, IL, USA
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18
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Shah L, Choi HW, Berrang-Ford L, Henostroza G, Krapp F, Zamudio C, Heymann SJ, Kaufman JS, Ciampi A, Seas C, Gotuzzo E, Brewer TF. Geographic predictors of primary multidrug-resistant tuberculosis cases in an endemic area of Lima, Peru. Int J Tuberc Lung Dis 2015; 18:1307-14. [PMID: 25299862 DOI: 10.5588/ijtld.14.0011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
SETTING Peru reports among the highest multidrug-resistant tuberculosis (MDR-TB) rates in the Americas, with a growing proportion in previously untreated tuberculosis (TB) cases. The identification of clusters of primary MDR-TB compared with drug-susceptible TB (DS-TB) could help prioritize interventions. OBJECTIVE To examine the clustering of primary MDR-TB case residences and their proximity to high-risk locations in San Juan de Lurigancho District, Lima, Peru. DESIGN Enrolled primary MDR-TB and primary DS-TB cases were interviewed and their primary residence was recorded using handheld Global Positioning System devices. Kuldorff's spatial scan statistic was used for cluster detection (SaTScan(TM), v. 9.1.1). Identified clusters were visualized in Quantum Geographic Information Systems software (v1.8.0). The following cluster centers were tested: a health centre with the highest TB and MDR-TB rates (Clinic X), a hospital and two prisons. Using regression analyses, we examined predictors of primary MDR-TB cases. RESULTS A statistically significant cluster of primary MDR-TB cases was identified within a 2.29 km radius around Clinic X. Proximity to Clinic X remained a significant predictor of primary MDR-TB in adjusted regression analyses. CONCLUSION We identified a hotspot of primary MDR-TB cases around Clinic X in a TB-endemic area. Causes of this clustering require investigation; targeted interventions for this high-risk area should be considered.
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Affiliation(s)
- L Shah
- Department of Epidemiology, Biostatistics & Occupational Health, McGill University, Montreal, Quebec, Canada
| | - H W Choi
- Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - L Berrang-Ford
- Department of Geography, McGill University, Montreal, Quebec, Canada
| | - G Henostroza
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - F Krapp
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - C Zamudio
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - S J Heymann
- Department of Epidemiology, Jonathan and Karin Fielding School of Public Health, University of California, Los Angeles, USA
| | - J S Kaufman
- Department of Epidemiology, Biostatistics & Occupational Health, McGill University, Montreal, Quebec, Canada
| | - A Ciampi
- Department of Epidemiology, Biostatistics & Occupational Health, McGill University, Montreal, Quebec, Canada
| | - C Seas
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - E Gotuzzo
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - T F Brewer
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, USA
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Li KH, Cheung YF, Choi HW. Whispering gallery mode lasing in optically isolated III-nitride nanorings. Opt Lett 2015; 40:2564-2567. [PMID: 26030558 DOI: 10.1364/ol.40.002564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
III-nitride nanorings fabricated from a combination of hybrid-nanosphere-lithography and laser lift-off processes is demonstrated. Being formed on an interfacial metallic layer optically coupling between the optical ring and its substrate is eliminated, maximizing optical confinement of whispering gallery resonant mode within the ring cavity. The tapered cross-sectional profile also promotes coupling of emitted light into resonant modes. Optically pumped lasing with a dominant peak at 421.5 nm is observed at room temperature, with threshold energy density of ∼6.5 mJ/cm2. Etch-induced sidewall roughness causes scattering of light at the interface to diminish confinement, and is also responsible for the mode-splitting effect according to finite-difference time-domain simulations.
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20
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Cheung WS, Cheung YF, Chen HT, Hui RSY, Waffenschmidt E, Choi HW. InGaN light-emitting diode stripes with reduced luminous exitance. Opt Express 2015; 23:15021-15028. [PMID: 26072858 DOI: 10.1364/oe.23.015021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
InGaN light-emitting diodes of stripe geometries have been demonstrated. The elongated geometry facilitates light spreading in the longitudinal direction. The chips are further shaped by laser-micromachining to have partially-inclined sidewalls. The light extraction efficiencies of such 3D chip geometries are enhanced by ~12% (~8% according to ray-trace simulations), leading to a reduction of junction temperatures. The effective emission area is also increased four times compared to a cubic chip. The stripe LEDs are thus more efficient emitters with reduced luminous exitance, making them more suitable for a wide range of lighting applications.
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21
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Zhang X, Cheung YF, Zhang Y, Choi HW. Whispering-gallery mode lasing from optically free-standing InGaN microdisks. Opt Lett 2014; 39:5614-5617. [PMID: 25360941 DOI: 10.1364/ol.39.005614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Optically pumped multi-mode whispering-gallery mode (WGM) lasing has been observed in optically free-standing InGaN/GaN quantum well microdisks at room temperature. The ∼6.6 μm optically isolated microdisks are patterned by microsphere lithography on GaN thin-films prepared by laser lift-off of the sapphire substrate, enabling superior optical confinement. The modes are determined to be of second order according to simulations. The lasing threshold is found to be ∼9.06 mJ/cm2, with a quality factor Q of ∼770 evaluated from the dominant mode at λ=430.2 nm, and a free space range (FSR) of 3.17 to 2.16 nm, which is mode-dependent.
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22
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Choi HW, Lee KH, Hur NH, Lim HB. Cerium oxide-deposited mesoporous silica nanoparticles for the determination of carcinoembryonic antigen in serum using inductively coupled plasma-mass spectrometry. Anal Chim Acta 2014; 847:10-5. [PMID: 25261895 DOI: 10.1016/j.aca.2014.08.041] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 08/13/2014] [Accepted: 08/14/2014] [Indexed: 12/31/2022]
Abstract
CeO2-deposited mesoporous silica nanoparticles were synthesized as a probe to determine carcinoembryonic antigen (CEA) in serum by inductively coupled plasma-mass spectrometry (ICP-MS). The prepared mesoporous nanoparticles were modified and tagged to the target for sandwich-type immunoassay. Fe3O4 magnetic nanoparticles (MNPs) were also synthesized and immobilized with antibody to extract the target biomarker. The calibration curve of the synthesized CeO2-deposited silica nanoparticles, which was plotted by the signal ratio of (140)Ce/(57)Fe measured by ICP-MS vs. the concentration of CEA, showed excellent linearity and sensitivity owing to the signal amplification and low spectral interference. Under optimal conditions, the sandwich-type analytical method was applied to determine CEA in serum spiked in the range of 0.001-5 ng mL(-1) and showed a limit of detection of 0.36 ng mL(-1). Since the deposited CeO2 in the mesoporous silica layer can be substituted by other metal compounds, various kinds of metal-deposited nanoparticles can be prepared as probe materials for multiplex detection in bioanalysis.
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Affiliation(s)
- H W Choi
- Department of Chemistry, NSBI, Dankook University, 126 Jukjeon-dong, Suji-gu, Yongin-si, Gyeonggi-do 448-701, South Korea
| | - K H Lee
- Department of Chemistry, Sogang University, Shinsu-dong, Mapo-gu, Seoul, South Korea
| | - N H Hur
- Department of Chemistry, Sogang University, Shinsu-dong, Mapo-gu, Seoul, South Korea
| | - H B Lim
- Department of Chemistry, NSBI, Dankook University, 126 Jukjeon-dong, Suji-gu, Yongin-si, Gyeonggi-do 448-701, South Korea.
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Choi HW, Miele K, Dowdy D, Shah M. Cost-effectiveness of Xpert® MTB/RIF for diagnosing pulmonary tuberculosis in the United States. Int J Tuberc Lung Dis 2014; 17:1328-35. [PMID: 24025386 DOI: 10.5588/ijtld.13.0095] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
SETTING Conventional approaches to tuberculosis (TB) diagnosis and resistance testing are slow. The Xpert® MTB/RIF assay is an emerging molecular diagnostic assay for rapid TB diagnosis, offering results within 2 hours. However, the cost-effectiveness of implementing Xpert in settings with low TB prevalence, such as the United States, is unknown. OBJECTIVE We evaluated the cost-effectiveness of incorporating Xpert into TB diagnostic algorithms in the United States compared to existing diagnostics. DESIGN A decision-analysis model compared current TB diagnostic algorithms in the United States to algorithms incorporating Xpert. Primary outcomes were the costs and quality-adjusted life years (QALYs) accrued with each strategy; cost-effectiveness was represented using incremental cost-effectiveness ratios (ICER). RESULTS Xpert testing of a single sputum sample from TB suspects is expected to result in lower total health care costs per patient (US2673) compared to diagnostic algorithms using only sputum microscopy and culture (US2728) and improved health outcomes (6.32 QALYs gained per 1000 TB suspects). Compared to existing molecular assays, implementation of Xpert in the United States would be considered highly cost-effective (ICER US39992 per QALY gained). CONCLUSION TB diagnostic algorithms incorporating Xpert in the United States are highly cost-effective.
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Affiliation(s)
- H W Choi
- Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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24
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Kim SW, Kim HK, Choi HW, Yoo DH, Kim EJ, Hahn SH. Photocatalytic activity of metal-inserted WO3 thin films prepared by RF magnetron sputtering. J Nanosci Nanotechnol 2013; 13:7053-7055. [PMID: 24245188 DOI: 10.1166/jnn.2013.7733] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Metal (Au,Pt)-inserted WO3 thin films were deposited on quartz glass using a radio frequency magnetron sputtering method. Their structural and optical properties were analyzed by scanning electron microscopy, X-ray diffractometry, absorption spectrometry, and photoluminescence spectrometry. The photocatalytic activities of the films were investigated by the measurement of photodecomposition of methylene blue under visible-ray irradiation. Metal-inserted WO3 films showed higher photocatalytic activity than WO3 film. Pt-inserted WO3 thin film showed the most effective decomposition efficiency, it is due to the high absorption and the suppression of recombination between photo-excited electrons and holes.
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Affiliation(s)
- Soon Wook Kim
- Department of Physics, University of Ulsan, Ulsan 680-749, Republic of Korea
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25
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Oh JY, Kang MS, Yoon H, Choi HW, An BK, Shin EG, Kim YJ, Kim MJ, Kwon JH, Kwon YK. The embryo lethality of Escherichia coli isolates and its relationship to the presence of virulence-associated genes. Poult Sci 2012; 91:370-5. [PMID: 22252350 DOI: 10.3382/ps.2011-01807] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The aims of this study were to determine if the chicken embryo lethality assay and the presence of 9 virulence-associated genes of Escherichia coli were correlated and to discover which virulence genes contributed most to embryo lethality. We examined 58 E. coli strains isolated from visceral organs of chickens with colibacillosis for the presence of 9 virulence genes (fimC, tsh, fyuA, irp2, iucD, cvi/cva, iss, astA, and vat) by PCR. The gene FimC (type I fimbriae) was detected with the highest prevalence in 93.1% of the isolates, followed by iucD (67.24%), iss (58.62%), tsh (34.48%), cvi/cva (34.48%), fyuA (32.76%), astA (31.0%), irp2 (27.59%), and vat (17.24%). The embryo mortality ranged from 5 to 100%; however, most of the isolates were moderately or highly virulent. High positive correlations were observed between the presence of virulence genes and chicken embryo lethality. In addition, presence of the iucD (aerobactin) gene was the trait that best contributed to embryo mortality by using the multivariate model. These results suggest that expression frequency of these 9 virulence genes is associated with embryo mortality, and the gene that best predicted embryo mortality was iucD.
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Affiliation(s)
- J Y Oh
- Animal, Plant and Fisheries Quarantine and Inspection Agency, Anyang, Kyunggi, Korea
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26
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Abstract
An ordered hexagonal closed-packed nanopillar array is fabricated on GaN. A metal coating is then applied to encapsulate the pillars for promoting optical confinement within the cylindrical cavity. Room-temperature lasing at 373 nm is observed under pulsed excitation, at a lasing threshold of 0.42 MW/cm2. With pillar diameters of around 980 nm, the number of modes overlapping the emission spectrum is reduced, giving rise to single-mode whispering gallery stimulated emission. Finite-difference time-domain simulations are carried out for the prediction of resonant frequencies and electric field patterns corresponding to the resonant modes.
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Affiliation(s)
- K H Li
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, China
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27
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Abstract
Blue GaN light emitting diodes (LEDs) in the shape of cuboids and circular disks have been fabricated by laser micromachining. The proposed circular geometry serves to enhance overall light extraction on a macro-scale and to improve uniformity of the emission pattern due to the rotational symmetry of the chip. Analysis of the chip shaping effect is carried out by ray-tracing simulations and further supported with mathematical modeling using ideal LED models, and subsequently verified with fabricated devices. In comparison, a 10% improvement in overall emission was observed for circular LEDs over the regular cuboids, consistent with simulations and calculations. The measured emission pattern from the circular LED confirms the axial symmetry of the emission beam.
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Affiliation(s)
- X H Wang
- Semiconductor Display and Lighting Laboratory, Department of Electrical and Electronic Engineering The University of Hong Kong, Pokfulam Road, Hong Kong
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28
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Abstract
A new design for a polychromatic light-emitting diode (LED) is proposed and demonstrated. LED chips of the primary colors are physically stacked on top of each other. Light emitted from each layer of the stack passes through each other, and thus is mixed naturally without additional optics. As a color-tunable device, a wide range of colors can be generated, making it suitable for display purposes. As a phosphor-free white light LED, luminous efficacy of 30 lm/watt was achieved.
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Affiliation(s)
- K N Hui
- Department of Electrical and Electronic Engineering, Semiconductor Display and Lighting Laboratory, The University of Hong Kong, Hong Kong
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29
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Hui KN, Fu WY, Ng WN, Leung CH, Lai PT, Wong KKY, Choi HW. Polychromatic light-emitting diodes with a fluorescent nanosphere opal coating. Nanotechnology 2008; 19:355203. [PMID: 21828836 DOI: 10.1088/0957-4484/19/35/355203] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A hexagonally close-packed array consisting of fluorescent nanospheres was coated onto short-wavelength GaN light-emitting diodes to demonstrate polychromatic white light emission. The spherical particles self-assemble into ordered three-dimensional opal structures, performing the role of color conversion to generate a polychromatic spectrum with smooth and uniform emission patterns. Different ratios of green and orange-red fluorescent nanospheres were mixed and coated onto high-extraction-efficiency micro-LEDs. Four devices with different shades of white emission were demonstrated. Device A, with a high content of orange-red nanospheres, offers the highest CRI value of 80, whereas device C with a well-balanced ratio of green and orange-red nanospheres exhibits color characteristics closest to ideal white with CIE coordinate at (0.34, 0.34). At 20 mA driving current, the luminous efficacy of the devices A, B, C, and D are 40.5 lm W(-1), 57.7 lm W(-1), 63.1 lm W(-1), and 67.2 lm W(-1) respectively, while the correlated color temperatures (CCTs) of the corresponding devices are 3587, 4778, 5271, and 13 000 K.
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Affiliation(s)
- K N Hui
- Department of Electrical and Electronic Engineering, University of Hong Kong, Hong Kong
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30
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Abstract
Instead of using conventional electron lithography, a two-dimensional photonic crystal consisting of a hexagonal array of triangular air-holes was created on the surface of a GaN LED substrate using microsphere lithography. The microspheres self-assemble into a single-layered hexagonal-close-packed array acting as an etch mask. A significant enhancement in photoluminescence intensity was recorded from the PhC LED structure. A twofold increase in electroluminescence was observed from the PhC LED compared to an as-grown LED with identical geometry. Besides geometrical factors due to surface roughening, the dispersive nature of PhCs and diffractive properties of the PhC as a grating contribute to the enhancement of light extraction from the LED.
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Affiliation(s)
- W N Ng
- Department of Electrical and Electronic Engineering, University of Hong Kong, Pokfulam road, Hong Kong
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31
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Abstract
An innovative spectral conversion scheme for light emitting diodes using fluorescent microspheres has been demonstrated. An optimally mixed proportion of green and red fluorescent microspheres were coated onto a high-extraction-efficiency GaN micro-LED with emission centred at 470 nm. The microspheres self-assemble into ordered hexagonally arrays, forming regular and uniform coating layers. Devices with cool and warm white emission were achieved. The bluish-white LED has a luminous efficacy of 27.3 lm/W (at 20 mA) with CIE coordinates of (0.26, 0.28) and 8500K CCT, while the yellowish-white LED has a luminous efficacy of 26.67 lm/W (at 20 mA) with CIE coordinates of (0.36, 0.43) and 13000K CCT.
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Affiliation(s)
- K N Hui
- Department of Electrical and Electronic Engineering, University of Hong Kong
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Choi HW, Farson DF, Bovatsek J, Arai A, Ashkenasi D. Direct-write patterning of indium-tin-oxide film by high pulse repetition frequency femtosecond laser ablation. Appl Opt 2007; 46:5792-9. [PMID: 17700755 DOI: 10.1364/ao.46.005792] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Ablation of indium oxide doped with tin oxide (ITO) from glass substrates is described. Laser pulse energy and focus spot size were varied in single-pulse, single-spot ablation tests and for ablation of linear features with scanned multiple pulses. The single-pulse ablation threshold of ITO was smaller than that of the glass substrate so the entire thickness of ITO could be removed in a single pulse or with overlying multiple pulses without the possibility of substrate ablation. Linear features could be created at much higher scanning speeds using a high repetition frequency (100 kHz) Yb fiber amplified laser as compared to a lower repetition frequency (2 kHz) laser. An analysis showed that incubation effects lowered ITO ablation thresholds when pulse frequency was high relative to scanning speed, contributing to large feasible scanning speeds for high pulse frequency lasers.
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Affiliation(s)
- H W Choi
- Laboratory for Multiscale Processing & Characterization, Ohio State University, Columbus 43221, USA
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Choi HW, Barakat AI. Modulation of ATP/ADP concentration at the endothelial surface by shear stress: effect of flow disturbance. Conf Proc IEEE Eng Med Biol Soc 2007; 2004:5065-8. [PMID: 17271456 DOI: 10.1109/iembs.2004.1404400] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The adenine nucleotides ATP and ADP modulate the release of endothelial-derived relaxing factors and hence play an important role in flow-mediated arterial vasoregulation. Adenine nucleotide concentration at the endothelial cell (EC) surface within an artery is determined by a balance of convective-diffusive delivery of blood-borne nucleotides to the EC surface, hydrolysis of these nucleotides at the cell surface, and flow-induced ATP release from ECs. Previous numerical simulations in a parallel plate flow chamber had demonstrated that flow-induced ATP release has a profound effect on nucleotide concentration under both steady and pulsatile flow conditions. In the present study, we have extended this analysis to probe the impact of disturbed flow downstream of a backward facing step on adenine nucleotide concentration at the EC surface. The results have demonstrated that over a wide range of applied wall shear stress, the ATP concentration at the EC surface drops abruptly within the disturbed flow zone due to increased nucleotide residence time within this region. The concentration is intricately sensitive to the kinetics of flow-induced ATP release, and this sensitivity is more pronounced at lower levels of wall shear stress.
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Affiliation(s)
- H W Choi
- Department of Mechanical & Aeronautical Engineering, California University, Davis, CA, USA
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Abstract
The frequency-dependent electrical data of the bismuth germanate silicate (BGSO) glasses have been discussed in the framework of the electric modulus representation and the power-law conductivity. The activation energies of the mean electric relaxation time and the direct current (dc) conductivity obtained by the complex modulus analysis show that the BGSO glasses satisfy the Barton, Nakajima, and Namikawa (BNN) relation. The proper relation between the exponent of the power-law conductivity and the stretched exponential of the modulus representation is shown. The temperature- and frequency-dependent characteristics of non-Debye behavior are discussed. The scaling properties of both the modulus M*(omega) and the alternating current (ac) conductivity sigma(omega) are examined.
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Affiliation(s)
- Y H Rim
- School of Liberal Arts, Semyung University, Chechon, Chungbuk 390-711, Korea
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Girkin JM, Gu E, Griffin C, Choi HW, Dawson MD, McConnell G. Use of confocal and multiphoton microscopy for the evaluation of micro-optical components and emitters. Microsc Res Tech 2004; 64:293-6. [PMID: 15481047 DOI: 10.1002/jemt.20085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We report on the application of confocal and multiphoton microscopic techniques for the evaluation of the latest generation of micro optical components. The optical emitting characteristics of arrays of matrix addressable GaN micrometer-sized light emitting diodes (micro-LEDs) have been measured using a commercial confocal microscope utilising the LEDs' own emission along with reflection confocal microscopy to determine the surface structure. Multiphoton induced luminescence from the 10-20-micron diameter emitters has also been used to examine the structure of the device and we compare this with electrically induced emission. In related work, the optical properties of micro lens arrays (10-100-micron diameter) fabricated in SiC, Sapphire, and Diamond have been determined using transmission confocal microscopy. Such optical microscopy techniques offer a simple, non-destructive method to determine the structure and performance of such novel devices.
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Affiliation(s)
- J M Girkin
- Institute of Photonics, Wolfson Centre, University of Strathclyde, Glasgow, G4 0NW, United Kingdom.
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Choi HW, Lemaux PG, Cho MJ. Long-term stability of transgene expression driven by barley endosperm-specific hordein promoters in transgenic barley. Plant Cell Rep 2003; 21:1108-1120. [PMID: 12836006 DOI: 10.1007/s00299-003-0630-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2002] [Revised: 02/27/2003] [Accepted: 03/02/2003] [Indexed: 05/24/2023]
Abstract
In order to evaluate the long-term stability of transgene expression driven by the B(1)- and D-hordein promoters in transgenic barley ( Hordeum vulgare L., 2 n=2 x=14), we analyzed plants from 15 independent transgenic barley lines [6 for uidA and 9 for sgfp(S65T)] produced via microprojectile bombardment of immature embryos; 4 were diploid and 11 were tetraploid. The expression and inheritance of transgenes were determined by analysis of functional transgene expression, polymerase chain reaction and fluorescence in situ hybridization (FISH). Ability to express transgenes driven by either B(1)- or D-hordein promoter was inherited in T(4) and later generations: T(4) (2 lines), T(5) (8 lines), T(6) (3 lines), T(8) (1 line) and T(9) (1 line). Homozygous transgenic plants were obtained from 12 lines [5 for uidA and 7 for sgfp(S65T)]; the remaining lines are currently being analyzed. The application of the FISH technique for physical mapping of chromosomes was useful for early screening of homozygous plants by examining for presence of the transgene. For example, one line expressing uidA, and shown to have doublet fluorescence signals on a pair of homologous chromosomes was confirmed as a homozygous line by its segregation ratio; additionally this line showed stable inheritance of the transgene to T(9) progeny. The expression of transgenes in most lines (14 out of 15 lines) driven by hordein promoters was stably transmitted to T(4) or later generations, although there was a skewed segregation pattern (1:1) from the T(1) generation onward in the remaining line. In contrast, transgene silencing or transgene loss under the control of the maize ubiquitin promoter was observed in progeny of only 6 out of 15 lines.
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Affiliation(s)
- H W Choi
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
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Cho MJ, Choi HW, Okamoto D, Zhang S, Lemaux PG. Expression of green fluorescent protein and its inheritance in transgenic oat plants generated from shoot meristematic cultures. Plant Cell Rep 2003; 21:467-474. [PMID: 12789450 DOI: 10.1007/s00299-002-0542-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2002] [Revised: 09/13/2002] [Accepted: 09/13/2002] [Indexed: 05/24/2023]
Abstract
The expression of green fluorescent protein (GFP) and its inheritance were studied in transgenic oat ( Avena sativa L.) plants transformed with a synthetic green fluorescent protein gene [sgfp(S65T)] driven by a rice actin promoter. In vitro shoot meristematic cultures (SMCs) induced from shoot apices of germinating mature seeds of a commercial oat cultivar, Garry, were used as a transformation target. Proliferating SMCs were bombarded with a mixture of plasmids containing the sgfp(S65T) gene and one of three selectable marker genes, phosphinothricin acetyltransferase (bar), hygromycin phosphotransferase (hpt) and neomycin phosphotransferase (nptII). Cultures were selected with bialaphos, hygromycin B and geneticin (G418), respectively, to identify transgenic tissues. From 289 individual explants bombarded with the sgfp(S65T) gene and one of the three selectable marker genes, 23 independent transgenic events were obtained, giving a 8.0% transformation frequency. All 23 transgenic events were regenerable, and 64% produced fertile plants. Strong GFP expression driven by the rice actin promoter was observed in a variety of tissues of the T(0) plants and their progeny in 13 out of 23 independent transgenic lines. Stable GFP expression was observed in T(2) progeny from five independent GFP-expressing lines tested, and homozygous plants from two lines were obtained. Transgene silencing was observed in T(0) plants and their progeny of some transgenic lines.
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Affiliation(s)
- M-J Cho
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
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Choi HW, Lemaux PG, Cho MJ. Use of fluorescence in situ hybridization for gross mapping of transgenes and screening for homozygous plants in transgenic barley ( Hordeum vulgare L.). Theor Appl Genet 2002; 106:92-100. [PMID: 12582875 DOI: 10.1007/s00122-002-0997-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2001] [Accepted: 04/18/2002] [Indexed: 05/24/2023]
Abstract
Introduced transgenes, uidA, sgfp (S65T) and/or bar, were localized using fluorescence in situ hybridization (FISH) on metaphase chromosomes of transgenic barley produced by microparticle bombardment of immature embryos. Of the 19 independent transgenic lines (eight diploid and 11 tetraploid), nine had uidA and ten had s gfp (S65T). All lines tested had three or more copies of the transgenes and 18 out of 19 lines had visibly different integration sites. At a gross level, it appeared that no preferential integration sites of foreign DNA among chromosomes were present in the lines tested; however, a distal preference for transgene integration was observed within the chromosome. In diploid T0 plants that gave a 3:1 segregation ratio of transgene expression in the T1, only single integration sites were detected on one of the homologous chromosomes. Homozygous diploid plants had doublet signals on a pair of homologous chromosomes. All tetraploid T0 plants that gave a 3:1 segregation ratio in the T1 generation had only a single integration site on one of the homologous chromosomes. In contrast, the single tetraploid T0 plant with a 35:1 segregation ratio in the T1 generation had doublet signals on a pair of homologous chromosomes. In the one tetraploid T0 line, which had a homozygote-like segregation ratio (45:0), there were doublet signals at two loci on separate chromosomes. We conclude that the application of FISH for analysis of transgenic plants is useful for the gross localization of transgene(s) and for early screening of homozygous plants.
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Affiliation(s)
- H W Choi
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
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Kwon TH, Kim MS, Choi HW, Joo CH, Cho MY, Lee BL. A masquerade-like serine proteinase homologue is necessary for phenoloxidase activity in the coleopteran insect, Holotrichia diomphalia larvae. Eur J Biochem 2000; 267:6188-96. [PMID: 11012672 DOI: 10.1046/j.1432-1327.2000.01695.x] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Previously, we reported the molecular cloning of cDNA for the prophenoloxidase activating factor-I (PPAF-I) that encoded a member of the serine proteinase group with a disulfide-knotted motif at the N-terminus and a trypsin-like catalytic domain at the C-terminus [Lee, S.Y., Cho, M.Y., Hyun, J.H., Lee, K.M., Homma, K.I., Natori, S. , Kawabata, S.I., Iwanaga, S. & Lee, B.L. (1998) Eur. J. Biochem. 257, 615-621]. PPAF-I is directly involved in the activation of pro-phenoloxidase (pro-PO) by limited proteolysis and the overall structure is highly similar to that of Drosophila easter serine protease, an essential serine protease zymogen for pattern formation in normal embryonic development. Here, we report purification and molecular cloning of cDNA for another 45-kDa novel PPAF from the hemocyte lysate of Holotrichia diomphalia larvae. The gene encodes a serine proteinase homologue consisting of 415 amino-acid residues with a molecular mass of 45 256 Da. The overall structure of the 45-kDa protein is similar to that of masquerade, a serine proteinase homologue expressed during embryogenesis, larval, and pupal development in Drosophila melanogaster. The 45-kDa protein contained a trypsin-like serine proteinase domain at the C-terminus, except for the substitution of Ser of the active site triad to Gly and had a disulfide-knotted domain at the N-terminus. A highly similar 45-kDa serine proteinase homologue was also cloned from the larval cDNA library of another coleopteran, Tenebrio molitor. By in vitro reconstitution experiments, we found that the purified 45-kDa serine proteinase homologue, the purified active PPAF-I and the purified pro-PO were necessary for expressing phenoloxidase activity in the Holotrichia pro-PO system. However, incubation of pro-PO with either PPAF-I or 45-kDa protein, no phenoloxidase activity was observed. Interestingly, when the 45-kDa protein was incubated with PPAF-I and pro-PO in the absence, but not in the presence of Ca2+, the 45-kDa protein was cleaved to a 35-kDa protein. RNA blot hybridization revealed that expression of the 45-kDa protein was increased in the Holotrichia hemolymph after Escherichia coli challenge.
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Affiliation(s)
- T H Kwon
- College of Pharmacy, Pusan National University, Jangjeon Dong, Kumjeong Ku, Pusan, Korea
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Lee KM, Lee KY, Choi HW, Cho MY, Kwon TH, Kawabata S, Lee BL. Activated phenoloxidase from Tenebrio molitor larvae enhances the synthesis of melanin by using a vitellogenin-like protein in the presence of dopamine. Eur J Biochem 2000; 267:3695-703. [PMID: 10848987 DOI: 10.1046/j.1432-1327.2000.01402.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
One of the biological functions of activated phenoloxidase in arthropods is the synthesis of melanin around invaded foreign materials. However, little is known about how activated phenoloxidase synthesizes melanin at the molecular level. Even though it has been suggested that the quinone derivatives generated by activated phenoloxidase might use endogenous protein components for melanin synthesis in arthropods, there is no report of protein components engaged in melanin synthesis induced by activated phenoloxidase. In this study, to isolate and characterize proteins involved in melanin synthesis, we prepared in vitro prophenoloxidase activating solution (designated G-100 solution), specifically showing phenoloxidase activity in the presence of Ca2+ and beta-1, 3-glucan, from the hemolymph of larvae of the coleopteran Tenebrio molitor by using a Sephadex G-100 column. When G-100 solution was incubated with dopamine to induce melanin synthesis in the presence of Ca2+ and beta-1,3-glucan, four types of protein (160 kDa, prophenoloxidase, phenoloxidase and 45 kDa) disappeared from SDS/PAGE under reducing conditions. Under identical conditions, but including phenylthiourea as a phenoloxidase inhibitor added to the G-100 solution, three of these proteins (160 kDa, phenoloxidase and 45 kDa) did not disappear. To characterize these melanization-engaging proteins, we first purified the 160-kDa melanization-engaging protein to homogeneity and raised a polyclonal antibody against it. Analysis of the cDNA revealed that it consisted of 1439 amino-acid residues and showed partial homology with Caenorhabditis elegans vitellogenin precursor-6 (19.7%). Western blot analysis showed that it disappeared when active phenoloxidase induced melanin synthesis. Furthermore, when the purified 160-kDa melanization-engaging protein was added to a G-100 solution deficient in it, melanin synthesis was enhanced compared with the same solution without the protein. These data support the conclusion that the 160-kDa vitellogenin-like protein is involved in arthropod melanin synthesis.
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Affiliation(s)
- K M Lee
- College of Pharmacy, Pusan National University, Korea
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Abstract
In Plasmodium vivax and Plasmodium ovale malaria, some of the liver stage parasites remain dormant. The activation of these dormant forms (called hypnozoite) can give rise to relapse weeks, months or years after the initial infection. To prevent relapses, a course of primaquine may be given as terminal prophylaxis to patients. Different strains of Plasmodium vivax vary in their sensitivity to primaquine and, recently, cases of relapse of Plasmodium vivax after this standard primaquine therapy were reported from various countries. We reported a case of primaquine resistant malaria which initially was thought to be relapsed caused by loss of terminal prophylaxis.
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Affiliation(s)
- D J Na
- Department of Internal Medicine, Sun General Hospital, Dae Jeon, Korea
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Cho MY, Choi HW, Moon GY, Kim MH, Kwon TH, Homma K, Natori S, Lee BL. An 86 kDa diapause protein 1-like protein is a component of early-staged encapsulation-relating proteins in coleopteran insect, Tenebrio molitor larvae. FEBS Lett 1999; 451:303-7. [PMID: 10371210 DOI: 10.1016/s0014-5793(99)00608-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Recently, we reported two novel early-staged encapsulation-relating proteins (56 kDa and 48 kDa ERPs) isolated from the hemolymph of coleopteran insect, Tenebrio molitor larvae [Cho et al. (1999) Eur. J. Biochem. (in press)]. Here, a cDNA clone for another early-staged encapsulation-relating protein (86 kDa) was isolated. We found that the 86 kDa protein shows high homology with insect diapause protein 1. The 86 kDa protein was localized in the fat body and hemolymph, but not hemocyte lysate. A significant level of 86 kDa protein was detected in pre-pupae stage, but it decreased rapidly at late larvae and pupae, and no protein was found in embryo, early larvae and adult stages. This diapause protein 1-like protein is likely to be a component of early-staged encapsulation-relating proteins in the insect cellular defense reaction.
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Affiliation(s)
- M Y Cho
- College of Pharmacy, Pusan National University, South Korea
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Yang XX, Choi HW, Yang SF, Li N. A UV-light activated cinnamic acid isomer regulates plant growth and gravitropism via an ethylene receptor-independent pathway. Aust J Plant Physiol 1999; 26:325-35. [PMID: 11542914 DOI: 10.1071/pp99007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
Abstract
Naturally occurring cinnamic acids (CA) exist in both trans- and cis-isoforms. UV-light irradiation of trans-CA is able to produce cis-CA. cis-CA was found to possess auxin-like activity before. In contrast, the vapor of cis-CA induced an epinastic response in tomato plants just as ethylene does. Given the existence of a double bond in and the gaseous nature of cis-CA, we suspected that cis-CA might also function as an ethylene-like compound. To distinguish between these possibilities, we selected an ethylene perception-deficient tomato plant, Never-ripe (Nr), and an ethylene biosynthesis-deficient tomato plant, A11. Not only did the vapor of cis-CA fail to trigger A11 tomato fruit ripening but it also delayed the ripening of banana fruit. Moreover, the vapor of cis-CA induced epinasty and the 'triple response' in both the wild type and Nr tomato plants, indicating that the vapor of cis-CA does not act via an ethylene receptor-dependent pathway. Furthermore, the vapor of cis-CA inhibited the negative gravitropic response of stems of both etiolated Nr seedlings and young plants, whereas ethylene had little effect on the negative gravitropism of the Nr plants. These results support the conclusion that the action sites of the vapor of cis-CA and ethylene are fundamentally different.
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Affiliation(s)
- X X Yang
- Department of Biology, The Hong Kong University of Science and Technology, Kowloon, Hong Kong SAR
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LaTrenta GS, Choi HW, Ward RF, Hoffman L, Neidich JA. Complete nasal agenesis with bilateral microphthalmia and unilateral duplication of the thumb. Plast Reconstr Surg 1995; 95:1101-4. [PMID: 7732122 DOI: 10.1097/00006534-199505000-00024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Complete nasal aplasia is an extremely rare clinical entity and most infants are stillborn when this is associated with holoprosencephaly. A viable 3-year-old infant born with frontonasal arrest without holoprosencephaly is presented. The child's main complaint was lack of a nasal airway, which made eating extremely difficult. A method for craniofacial reconstruction of the nasopharynx is presented.
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Affiliation(s)
- G S LaTrenta
- Division of Plastic and Reconstructive Surgery, New York Hospital-Cornell Medical Center, New York, N.Y., USA
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Choi HW, Breman JG, Teutsch SM, Liu S, Hightower AW, Sexton JD. The effectiveness of insecticide-impregnated bed nets in reducing cases of malaria infection: a meta-analysis of published results. Am J Trop Med Hyg 1995; 52:377-82. [PMID: 7771600 DOI: 10.4269/ajtmh.1995.52.377] [Citation(s) in RCA: 117] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The use of insecticide-impregnated bed nets to minimize human-vector contact may reduce the incidence of malaria. Consequently, several field trials have evaluated their effectiveness as a malaria prevention strategy. A meta-analysis of published reports of field trials that measured the incidence of infections was performed to provide a measure of the effectiveness of insecticide-treated bed nets in preventing clinical malaria. Subsetted analyses were performed on the 10 field trials to calculate pooled incidence rate ratios of infection among the study groups. For the studies comparing insecticide-impregnated bed nets with untreated bed nets, the summary incidence rate ratio for acquiring malarial infections was 0.757 (95% confidence interval [CI] = 0.612-0.938), representing a reduction of 24%. For the studies comparing permethrin-impregnated bed nets with controls without bed nets, the summary incidence rate ratio was 0.497 (95% CI = 0.417-0.592) (Rothman-Boice heterogeneity statistics = 17.27 [P = 0.004] and 23.55 [P = 0.0003], respectively). These data suggest that insecticide-impregnated bed nets are effective in preventing malaria, decreasing the incidence rate ratio by approximately 50% in field trials performed to date.
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Affiliation(s)
- H W Choi
- Epidemiology Program Office, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
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Abstract
Subsequent to 22 hr of deprivation of water, 40 male rats were given daily access to water and a sweetened ethanol solution for 2 hr each day for 24 days. Twenty of the rats had this opportunity to take fluids during the light-phase of the circadian cycle while the other twenty were given it during the dark. Prior to the 24 days, some rats (half of each group) were implanted subcutaneously with osmotic pumps giving them constant infusions of morphine (0.6 mg/kg/hr). Across daily sessions, all rats gradually increased their intakes of ethanol with the greatest increases among those having morphine and taking fluids during the light-phase. The rats which drank during the dark gained more weight than the others and the most marked gains in weight were by those receiving no morphine. The data support the conclusion that some general disruption resulting from the schedule of presentation of fluids during the day qualifies as a setting condition for heightened intake of ethanol.
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Affiliation(s)
- H W Choi
- Department of Psychology, Rensselaer Polytechnic Institute, Troy, NY 12180-3590
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