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Kim S, Yoon J, Kim HD, Choi SJ. Carbon Nanotube Synaptic Transistor Network for Pattern Recognition. ACS APPLIED MATERIALS & INTERFACES 2015; 7:25479-25486. [PMID: 26512729 DOI: 10.1021/acsami.5b08541] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Inspired by the human brain, a neuromorphic system combining complementary metal-oxide semiconductor (CMOS) and adjustable synaptic devices may offer new computing paradigms by enabling massive neural-network parallelism. In particular, synaptic devices, which are capable of emulating the functions of biological synapses, are used as the essential building blocks for an information storage and processing system. However, previous synaptic devices based on two-terminal resistive devices remain challenging because of their variability and specific physical mechanisms of resistance change, which lead to a bottleneck in the implementation of a high-density synaptic device network. Here we report that a three-terminal synaptic transistor based on carbon nanotubes can provide reliable synaptic functions that encode relative timing and regulate weight change. In addition, using system-level simulations, the developed synaptic transistor network associated with CMOS circuits can perform unsupervised learning for pattern recognition using a simplified spike-timing-dependent plasticity scheme.
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Jang JT, Park J, Ahn BD, Kim DM, Choi SJ, Kim HS, Kim DH. Study on the photoresponse of amorphous In-Ga-Zn-O and zinc oxynitride semiconductor devices by the extraction of sub-gap-state distribution and device simulation. ACS APPLIED MATERIALS & INTERFACES 2015; 7:15570-15577. [PMID: 26094854 DOI: 10.1021/acsami.5b04152] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Persistent photoconduction (PPC) is a phenomenon that limits the application of oxide semiconductor thin-film transistors (TFTs) in optical sensor-embedded displays. In the present work, a study on zinc oxynitride (ZnON) semiconductor TFTs based on the combination of experimental results and device simulation is presented. Devices incorporating ZnON semiconductors exhibit negligible PPC effects compared with amorphous In-Ga-Zn-O (a-IGZO) TFTs, and the difference between the two types of materials are examined by monochromatic photonic C-V spectroscopy (MPCVS). The latter method allows the estimation of the density of subgap states in the semiconductor, which may account for the different behavior of ZnON and IGZO materials with respect to illumination and the associated PPC. In the case of a-IGZO TFTs, the oxygen flow rate during the sputter deposition of a-IGZO is found to influence the amount of PPC. Small oxygen flow rates result in pronounced PPC, and large densities of valence band tail (VBT) states are observed in the corresponding devices. This implies a dependence of PPC on the amount of oxygen vacancies (VO). On the other hand, ZnON has a smaller bandgap than a-IGZO and contains a smaller density of VBT states over the entire range of its bandgap energy. Here, the concept of activation energy window (AEW) is introduced to explain the occurrence of PPC effects by photoinduced electron doping, which is likely to be associated with the formation of peroxides in the semiconductor. The analytical methodology presented in this report accounts well for the reduction of PPC in ZnON TFTs, and provides a quantitative tool for the systematic development of phototransistors for optical sensor-embedded interactive displays.
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Lee J, Jang J, Choi B, Yoon J, Kim JY, Choi YK, Kim DM, Kim DH, Choi SJ. A Highly Responsive Silicon Nanowire/Amplifier MOSFET Hybrid Biosensor. Sci Rep 2015. [PMID: 26197105 PMCID: PMC4508832 DOI: 10.1038/srep12286] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
This study demonstrates a hybrid biosensor comprised of a silicon nanowire (SiNW) integrated with an amplifier MOSFET to improve the current response of field-effect-transistor (FET)-based biosensors. The hybrid biosensor is fabricated using conventional CMOS technology, which has the potential advantage of high density and low noise performance. The biosensor shows a current response of 5.74 decades per pH for pH detection, which is 2.5 × 105 times larger than that of a single SiNW sensor. In addition, we demonstrate charged polymer detection using the biosensor, with a high current change of 4.5 × 105 with a 500 nM concentration of poly(allylamine hydrochloride). In addition, we demonstrate a wide dynamic range can be obtained by adjusting the liquid gate voltage. We expect that this biosensor will be advantageous and practical for biosensor applications which requires lower noise, high speed, and high density.
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Song GG, Bae SC, Seo YH, Kim JH, Choi SJ, Ji JD, Lee YH. Meta-analysis of functional MBL polymorphisms. Associations with rheumatoid arthritis and primary Sjögren's syndrome. Z Rheumatol 2015; 73:657-64. [PMID: 25060516 DOI: 10.1007/s00393-014-1408-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
OBJECTIVE The aim of this study was to determine whether functional mannose-binding lectin gene (MBL) polymorphisms are associated with the susceptibility to rheumatoid arthritis (RA) or primary Sjögren's syndrome (pSS). METHODS A meta-analysis was conducted to investigate the potential association of RA or pSS with MBL polymorphisms, including the codon 54 (allele B), codon 57 (allele C), and codon 52 (allele D) variants of exon 1, and the - 550 (allele L) and - 221 (allele X) promoter variants. RESULTS A total of 12 comparative studies, including eight RA (1623 patients and 1671 controls) and four pSS (280 patients and 516 controls) studies, were included in the meta-analysis. The meta-analysis revealed no association between the MBL B allele and RA in the overall study population (odds ratio [OR] 0.991, 95 % confidence interval [CI] 0.726-1.355, p = 0.957). However, the meta-analysis showed significant associations between the MBL D, H, and X alleles and RA in the overall population (OR 1.708, 95 % CI 1.077-2.707, p = 0.023; OR 1.936, 95 % CI 1.218-3.078, p = 0.005; OR 1.582, 95 % CI 1.216-2.057, p = 0.001, respectively). An association was found between the MBL B allele and pSS in the overall study population (OR 0.691, 95 % CI 0.541-0.917, p = 0.010). Stratification by ethnicity indicated a trend toward an association between the B allele and pSS in European populations, but no association in Asian populations (OR 0.689, 95 % CI 0.465-1.021, p = 0.063; OR 0.896, 95 % CI 0.311-2.562, p = 0.838, respectively). CONCLUSION This meta-analysis demonstrated an association between the MBL D, L, and X alleles and the risk of RA. It also demonstrated an association between the MBL B allele and the susceptibility to pSS, suggesting a protective role of the MBL B allele against the development of pSS.
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Choi SJ, Yeum KJ, Park SJ, Choi B, Joo NS. Dietary calcium and Framingham Risk Score in vitamin D deficient male (KNHANES 2009-2011). Yonsei Med J 2015; 56:845-52. [PMID: 25837195 PMCID: PMC4397459 DOI: 10.3349/ymj.2015.56.3.845] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
PURPOSE The association between excess calcium intake and cardiovascular mortality has already been reported. In the present study, we investigated the relation between dietary calcium intake and Framingham Risk Score (FRS) according to serum 25-hydroxyvitamin D [25(OH)D] status. MATERIALS AND METHODS A total of 7809 subjects (3452 males and 4357 female) aged over 40 years were selected for this cross-sectional study from data obtained from the Korea National Health and Nutrition Examination Survey (2008-2011). Daily dietary calcium intake was categorized into <300, 300-600, 600-900, 900-1200, and >1200 mg/day and serum 25(OH)D concentration classified into <50, 50-75, >75 mmol/L. The FRS was compared by the daily dietary calcium intake categories according to 25(OH)D concentration after adjustment with relevant variables in both genders. RESULTS Higher FRS was observed in males with both <300 mg and >1200 mg of dietary calcium intake and females with <300 mg of dietary calcium intake without adjustment. The significantly higher FRS remained in the <300 mg and >1200 mg of dietary calcium intake groups in both genders after adjustments for relevant variables. FRS was significantly higher in the group with >1200 mg of dietary calcium intake and serum 25(OH)D <50 nmol/L, which was the male only vitamin D deficient group. CONCLUSION Very low (<300 mg/day) and excess (>1200 mg/day) dietary calcium intake were related with higher FRS in both genders. In particular, higher FRS was observed in the excess (>1200 mg/day) dietary calcium intake male group under vitamin D deficiency (<50 nmol/L).
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Bang DH, Shin WS, Choi SJ, Choi HS. Comparison of the effect of weight-bearing and non-weight-bearing positions on knee position sense in patients with chronic stroke. J Phys Ther Sci 2015; 27:1203-6. [PMID: 25995589 PMCID: PMC4434010 DOI: 10.1589/jpts.27.1203] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 12/11/2014] [Indexed: 12/30/2022] Open
Abstract
[Purpose] The purpose of this study was to investigate the knee joint proprioception in weight-bearing (WB) and non-weight-bearing (NWB) positions and to study the difference between the methods in chronic stroke patients. [Subjects and Methods] The subjects were 15 stroke patients who were randomly scheduled to perform both positions by a physical therapist not involved in the study. The subjects performed the positions (WB and NWB) based on a randomized controlled cross-sectional design. WB subjects were positioned in one-leg standing to assess the knee joint position sense. NWB subjects were instructed to sit comfortably in a chair and maintain the knees at 90° of flexion with the leg out of the plinth. [Results] The results revealed that the WB position showed a significant difference in knee position sense. The proprioception sense in the WB position was a higher than that in the NWB position. [Conclusion] The knee proprioception of chronic stroke patients differs between the weight-bearing and non-weight-bearing positions.
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Lee YH, Bae SC, Choi SJ, Ji JD, Song GG. Associations between the functional CD40 rs4810485 G/T polymorphism and susceptibility to rheumatoid arthritis and systemic lupus erythematosus: a meta-analysis. Lupus 2015; 24:1177-83. [DOI: 10.1177/0961203315583543] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 03/30/2015] [Indexed: 11/16/2022]
Abstract
Objective The aim of this study was to determine whether the functional CD40 rs4810485 G/T polymorphism is associated with susceptibility to rheumatoid arthritis (RA) or with susceptibility to systemic lupus erythematosus (SLE). Methods A series of meta-analyses were conducted to test for association between the CD40 rs4810485 G/T polymorphism and RA or SLE. Results A total of 21 comparisons involving 15,095 patients and 27,050 controls for RA, and 1353 patients and 2342 controls for SLE were considered. Meta-analysis showed a significant association between the CD40 rs4810485 T allele and RA in all subjects (odds ratio (OR) 0.890, 95% confidence interval (CI) 0.846–0.936, p = 5.5 × 10−7). After stratification by ethnicity, the CD40 T allele was found to be significantly associated with RA in Europeans (OR 0.879, 95% CI 0.848–0.901, p = 3.0 × 10−9). A similar pattern of association was observed between the CD40 T allele and RA when the analysis was performed using the recessive, dominant, and additive models. Meta-analysis also showed a significant association between the CD40 polymorphism and SLE in Europeans (OR for the T allele 0.715, 95% CI 0.641–0.832, p = 1.4 × 10−6). Conclusions Our meta-analyses confirm that the CD40 rs4810485 G/T polymorphism is associated with susceptibility to RA and SLE in Europeans.
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Han SB, Gwak MS, Choi SJ, Ko JS, Kim GS, Son HJ, Shin JC. Risk factors for inadvertent hypothermia during adult living-donor liver transplantation. Transplant Proc 2015; 46:705-8. [PMID: 24767329 DOI: 10.1016/j.transproceed.2013.11.091] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 11/15/2013] [Indexed: 01/10/2023]
Abstract
BACKGROUND Hypothermia (core temperature <35°C) causes multiple physiologic disturbances, including coagulopathy and cardiac dysfunction. Patients undergoing liver transplantation are at risk of inadvertent hypothermia and might be more vulnerable to its adverse effects. We sought to identify the factors contributing to hypothermia during living-donor liver transplantation (LDLT), which have not yet been studied in depth. METHODS Medical records of 134 recipients who underwent adult-to-adult LDLT were reviewed. Core temperature at the following time points were taken: anesthetic induction, skin incision, start and end of the anhepatic phase, and hourly after hepatic reperfusion. RESULTS Of 134 recipients, 29 (21.6%) developed hypothermia during surgery. Four independent risk factors for hypothermia were identified: small body weight-to-body surface area ratio, acute hepatic failure, high Model for End-Stage Liver Disease (MELD) score, and low graft-to-recipient weight ratio. The amount of core temperature drop was positively correlated with the number of involved risk factors. Each risk factor had a respective contribution according to the operative phases: body weight-to-body surface area ratio and the MELD score for the preanhepatic phase, acute deterioration of hepatic failure for the anhepatic phase, and graft-to-recipient weight ratio was for the postreperfusion phase. CONCLUSIONS Hypothermia was independently associated with the recipient's morphometric characteristics, emergency of end-stage liver disease, MELD score, and graft volume. These factors showed a cumulative effect, and the role of each factor was different according to the operative phase. These results should aid in the development of an optimal thermal strategy during LDLT.
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Wong MY, Borgkvist A, Choi SJ, Mosharov EV, Bamford NS, Sulzer D. Dopamine-dependent corticostriatal synaptic filtering regulates sensorimotor behavior. Neuroscience 2015; 290:594-607. [PMID: 25637802 DOI: 10.1016/j.neuroscience.2015.01.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 01/12/2015] [Accepted: 01/15/2015] [Indexed: 10/24/2022]
Abstract
Modulation of corticostriatal synaptic activity by dopamine is required for normal sensorimotor behaviors. After loss of nigrostriatal dopamine axons in Parkinson's disease, l-3,4-dihydroxyphenlalanine (l-DOPA) and dopamine D2-like receptor agonists are used as replacement therapy, although these drugs also trigger sensitized sensorimotor responses including dyskinesias and impulse control disorders. In mice, we lesioned dopamine projections to the left dorsal striatum and assayed unilateral sensorimotor deficits with the corridor test as well as presynaptic corticostriatal activity with the synaptic vesicle probe, FM1-43. Sham-lesioned mice acquired food equivalently on both sides, while D2 receptor activation filtered the less active corticostriatal terminals, a response that required coincident co-activation of mGlu-R5 metabotropic glutamate and CB1 endocannabinoid receptors. Lesioned mice did not acquire food from their right, but overused that side following treatment with l-DOPA. Synaptic filtering on the lesioned side was abolished by either l-DOPA or a D2 receptor agonist, but when combined with a CB1 receptor antagonist, l-DOPA or D2 agonists normalized both synaptic filtering and behavior. Thus, high-pass filtering of corticostriatal synapses by the coordinated activation of D2, mGlu-R5, and CB1 receptors is required for normal sensorimotor response to environmental cues.
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Park SJ, Son BH, Choi SJ, Kim HS, Ahn YH. Sensitive detection of yeast using terahertz slot antennas. OPTICS EXPRESS 2014; 22:30467-72. [PMID: 25606992 DOI: 10.1364/oe.22.030467] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We demonstrated sensitive detection of individual yeast cells and yeast films by using slot antenna arrays operating in the terahertz frequency range. Microorganisms located at the slot area cause a shift in the resonant frequency of the THz transmission. The shift was investigated as a function of the surface number density for a set of devices fabricated on different substrates. In particular, sensors fabricated on a substrate with relatively low permittivity demonstrate higher sensitivity. The frequency shift decreases with increasing slot antenna width for a fixed coverage of yeast film, indicating a field enhancement effect. Furthermore, the vertical range of the effective sensing volume has been studied by varying the thickness of the yeast film. The resonant frequency shift saturates at 3.5 μm for a slot width of 2 μm. In addition, the results of finite-difference time-domain simulations are in good agreement with our experimental data.
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Bang DH, Shin WS, Choi SJ. The effects of modified constraint-induced movement therapy combined with trunk restraint in subacute stroke: a double-blinded randomized controlled trial. Clin Rehabil 2014; 29:561-9. [PMID: 25246609 DOI: 10.1177/0269215514552034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Accepted: 08/27/2014] [Indexed: 12/31/2022]
Abstract
OBJECTIVE To investigate the effects of a modified constraint-induced movement therapy (mCIMT) with trunk restraint in subacute stroke patients. DESIGN Double-blind, randomized controlled trial. SETTING Rehabilitation clinic. PARTICIPANTS Eighteen subacute stroke patients with moderate motor impairment. INTERVENTIONS The patients were treated with either mCIMT combined with trunk restraint or mCIMT for 5 days per week for 4 weeks. The mCIMT combined with trunk restraint group participated in structured intervention sessions for use of the more affected upper-extremity in task-oriented activities with trunk restraint for 1 hour per day, and with the less affected upper-extremity restrained for 5 hours per day weeks. The mCIMT group followed the same protocol without trunk restraint. MAIN OUTCOME MEASURES The outcome measures included the action research arm test (ARAT), the Fugl-Meyer assessment (FMA), the modified Barthel index (MBI), the motor activity log (MAL) and the maximal elbow extension angle during reaching (MEEAR) were completed at baseline and post intervention. RESULTS The mCIMT combined with trunk restraint group exhibited more improved in the ARAT, FMA, MBI, MAL and MEEAR compared with the mCIMT group. Statistical analyses showed significantly different in ARAT (P = 0.046), FMA (P = 0.008), MBI (P = 0.001), MAL-AOU (P = 0.024), MAL-QOM (P = 0.010) and MEEAR (P = 0.001) between groups. CONCLUSIONS These results suggest that mCIMT combined with trunk restraint is more helpful to improve upper-extremity function than mCIMT only in subacute stroke patients with moderate motor impairment.
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Choi SJ, Shin WS, Oh BK, Shim JK, Bang DH. Effect of training with whole body vibration on the sitting balance of stroke patients. J Phys Ther Sci 2014; 26:1411-4. [PMID: 25276025 PMCID: PMC4175246 DOI: 10.1589/jpts.26.1411] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 03/09/2014] [Indexed: 11/24/2022] Open
Abstract
[Purpose] The purpose of this study was to determine the effects of task-oriented training with whole body vibration (WBV) on the sitting balance of stroke patients. [Subjects] The subjects were 30 stroke patients who were randomly divided into experimental (n1=15) and control (n2=15) groups. [Methods] Subjects in both groups received general training five times per week. Subjects in the experimental group practiced an additional task-oriented training program with WBV, which was performed for 15 minutes, five times per week, for four weeks. The center of pressure (COP) path length and average velocity were used to assess subjects static sitting balance, and the Modified Functional Reach Test (MFRT) was used to assess their dynamic sitting balance. The paired t-test was performed to test the significance of differences between before and after the intervention. The independent t-test was conducted to test the significance of differences between the groups. [Results] Following the intervention, the experimental group showed a significant change in MFRT. [Conclusion] The results of this study suggest that task-oriented training with WBV is feasible and efficacious for stroke patients.
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Park SJ, Hong JT, Choi SJ, Kim HS, Park WK, Han ST, Park JY, Lee S, Kim DS, Ahn YH. Detection of microorganisms using terahertz metamaterials. Sci Rep 2014; 4:4988. [PMID: 24832607 PMCID: PMC4023130 DOI: 10.1038/srep04988] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 04/28/2014] [Indexed: 12/23/2022] Open
Abstract
Microorganisms such as fungi and bacteria cause many human diseases and therefore rapid and accurate identification of these substances is essential for effective treatment and prevention of further infections. In particular, contemporary microbial detection technique is limited by the low detection speed which usually extends over a couple of days. Here we demonstrate that metamaterials operating in the terahertz frequency range shows promising potential for use in fabricating the highly sensitive and selective microbial sensors that are capable of high-speed on-site detection of microorganisms in both ambient and aqueous environments. We were able to detect extremely small amounts of the microorganisms, because their sizes are on the same scale as the micro-gaps of the terahertz metamaterials. The resonant frequency shift of the metamaterials was investigated in terms of the number density and the dielectric constants of the microorganisms, which was successfully interpreted by the change in the effective dielectric constant of a gap area.
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Seol ML, Im H, Moon DI, Woo JH, Kim D, Choi SJ, Choi YK. Design strategy for a piezoelectric nanogenerator with a well-ordered nanoshell array. ACS NANO 2013; 7:10773-9. [PMID: 24255989 DOI: 10.1021/nn403940v] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The piezoelectric nanogenerator (PNG) has been spotlighted as a promising candidate for use as a sustainable power source in wireless system applications. For the further development of PNGs, structural optimization is essential, but the structural analysis progress in this area has been scant. In the present study, we proposed a PNG with a well-ordered nanoshell array structure. The nanoshell structure has been considered as an effective core nanostructure for PNGs due to its effective stress confinement effect but has not been experimentally introduced thus far due to the challenging fabrication method required. To produce a controllable nanoshell structure, a top-down silicon nanofabrication technique which involves advanced spacer lithography is introduced. A comprehensive design strategy to enhance the piezoelectric performance is proposed in terms of the nanoshell diameter and shell-to-shell space. Both simulated and measured data confirm that an extremely high density of a structure is not always the best answer to maximize the performance. The highest amount of power can be achieved when the shell diameter and shell-to-shell space are within their proper ranges. The structural design strategy studied in this work provides a guideline for the further structural developments of PNG.
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Park DS, Lee DY, Choi SJ, Shin WS. Reliability and Validity of the Balancia using Wii Balance Board for Assessment of Balance with Stroke Patients. ACTA ACUST UNITED AC 2013. [DOI: 10.5762/kais.2013.14.6.2767] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Chung HE, Yu J, Baek M, Lee JA, Kim MS, Kim SH, Maeng EH, Lee JK, Jeong J, Choi SJ. Toxicokinetics of zinc oxide nanoparticles in rats. ACTA ACUST UNITED AC 2013. [DOI: 10.1088/1742-6596/429/1/012037] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Gwak MS, Kim WH, Choi SJ, Lee JJ, Ko JS, Kim GS, Kim YI, Kim MH. Arthroscopic shoulder surgery under general anesthesia with brachial plexus block: postoperative respiratory dysfunction of combined obstructive and restrictive pathology. Anaesthesist 2013; 62:113-20. [PMID: 23400711 DOI: 10.1007/s00101-012-2125-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2012] [Revised: 12/04/2012] [Accepted: 12/10/2012] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Changes in respiratory parameters and pulmonary function tests were evaluated after shoulder arthroscopic surgery with brachial plexus block (BPB). The purpose of this study was to identify the mechanism of respiratory dysfunction after this type of surgery. METHODS Patients undergoing arthroscopic rotator cuff repair under general anesthesia (GA) with BPB were enrolled in the arthroscopy group (n = 30) while those undergoing open reduction of a clavicle or humerus fracture under GA were enrolled in the control group (n = 30). Forced vital capacity (FVC) and forced expiratory volume 1 s (FEV(1)) were measured at the outpatient clinic stage (#1) before (#2) and 20 min after BPB (#3) and 1 h after extubation (#4). Respiratory variable measurements along with the cuff leak test were performed 5 min after surgical positioning (T1) and at the start of skin closure (T2). Respiratory discomfort was evaluated after extubation. The upper airway diameters and soft tissue depth of chest wall were also measured by ultrasonography at stages #3 and #4. RESULTS Static compliance decreased significantly at T2 in the arthroscopy group (50 ± 11 at T1 vs. 44 ± 9 ml/cm H(2)O at T2, p =0.035) but not in the control group. The incidence of positive cuff leak tests at T2 was significantly higher in the arthroscopy group than in the control group (47% in the arthroscopy group vs. 17% in controls, p =0.010). While FEV(1) and FVC remained stable at stages #1 and #2, FVC and FEV(1) decreased at stages #3 and #4 only in the arthroscopy group (FVC in arthroscopy group, #2: 3.26 ± 0.77 l; #3: 2.55 ± 0.63 l, p =0.015 vs. #2; #4: 2.66 ± 0.41 l, p =0.040 vs. #2). The subglottic diameter decreased at #4 in the arthroscopy group, while no changes occurred in the control group (0.70 ± 0.21 cm vs. 0.85 ± 0.23 cm in the arthroscopy and control groups, respectively, p =0.011). Depth of skin to pleura increased at both intercostal spaces 1-2 and 3-4 in the arthroscopy group. There were three cases of hypoxia (S(p)O(2) < 95%) with room air in the arthroscopy group while none occurred in the controls. CONCLUSION Shoulder arthroscopic surgery under GA with BPB induced both restrictive and obstructive pathologies. It is important to maintain a high level of awareness for the potential negative respiratory effects of this surgery especially for subjects with pre-existing cardiopulmonary disease. The measurements in this study would be useful to monitor the risk of respiratory dysfunction in these patients.
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Lee SH, Lee MW, Yoo KH, Kim DS, Son MH, Sung KW, Cheuh H, Choi SJ, Oh W, Yang YS, Koo HH. Co-transplantation of third-party umbilical cord blood-derived MSCs promotes engraftment in children undergoing unrelated umbilical cord blood transplantation. Bone Marrow Transplant 2013; 48:1040-5. [DOI: 10.1038/bmt.2013.7] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 01/05/2013] [Accepted: 01/10/2013] [Indexed: 12/11/2022]
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Choi SJ, Bennett P, Takei K, Wang C, Lo CC, Javey A, Bokor J. Short-channel transistors constructed with solution-processed carbon nanotubes. ACS NANO 2013; 7:798-803. [PMID: 23259742 DOI: 10.1021/nn305277d] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We develop short-channel transistors using solution-processed single-walled carbon nanotubes (SWNTs) to evaluate the feasibility of those SWNTs for high-performance applications. Our results show that even though the intrinsic field-effect mobility is lower than the mobility of CVD nanotubes, the electrical contact between the nanotube and metal electrodes is not significantly affected. It is this contact resistance which often limits the performance of ultrascaled transistors. Moreover, we found that the contact resistance is lowered by the introduction of oxygen treatment. Therefore, high-performance solution-processed nanotube transistors with a 15 nm channel length were obtained by combining a top-gate structure and gate insulators made of a high-dielectric-constant ZrO(2) film. The combination of these elements yields a performance comparable to that obtained with CVD nanotube transistors, which indicates the potential for using solution-processed SWNTs for future aggressively scaled transistor technology.
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Seol ML, Ahn JH, Choi JM, Choi SJ, Choi YK. Self-aligned nanoforest in silicon nanowire for sensitive conductance modulation. NANO LETTERS 2012; 12:5603-5608. [PMID: 23066892 DOI: 10.1021/nl3026955] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A self-aligned and localized nanoforest structure is constructed in a top-down fabricated silicon nanowire (SiNW). The surface-to-volume ratio (SVR) of the SiNW is enhanced due to the local nanoforest formation. The conductance modulation property of the SiNWs, which is an important characteristic in sensor and charge transfer based applications, can be largely enhanced. For the selective modification of the channel region, localized Joule-heating and subsequent metal-assisted chemical etching (mac-etch) are employed. The nanoforest is formed only in the channel region without misalignment due to the self-aligned process of Joule-heating. The modified SiNW is applied to a porphyrin-silicon hybrid device to verify the enhanced conductance modulation. The charge transfer efficiency between the porphyrin and the SiNW, which is caused by external optical excitation, is clearly increased compared to the initial SiNW. The effect of the local nanoforest formation is enhanced when longer etching times and larger widths are used.
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Seol ML, Choi SJ, Choi JM, Ahn JH, Choi YK. Hybrid porphyrin-silicon nanowire field-effect transistor by opto-electrical excitation. ACS NANO 2012; 6:7885-7892. [PMID: 22882562 DOI: 10.1021/nn303260a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A porphyrin-silicon nanowire (Si-NW) hybrid field-effect transistor is introduced. The hybrid device has separate electrical and optical gates surrounding the Si-NW channel. Porphyrin, a component of chlorophyll, is employed as an optical gate to modulate the potential of the Si-NW channel. Due to the independently formed hybrid gates, both optical and electrical excitation can effectively modulate the device. The exposed porphyrin optical gate responds to the optical excitation, and independently formed electrical gates respond to the electrical excitation. Charge transfer characteristics between a semiconductor channel and the porphyrin optical gate are deeply investigated. Optical, electrical, and opto-electrical excitation methods are employed to analyze the charging and discharging behaviors. Of these methods, opto-electrical excitation enables the strongest charge transfer because the inversion electron formation by an electrical pulse and the photoinduced charge transfer by an optical stimulus are affected simultaneously. Discharging processes, such as rapid discharging, exponential detrapping, and the formation of metastable states are also analyzed.
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Hahm TS, Ahn HJ, Ryu S, Gwak MS, Choi SJ, Kim JK, Yu JM. Combined carbamazepine and pregabalin therapy in a rat model of neuropathic pain. Br J Anaesth 2012; 109:968-74. [PMID: 22936823 DOI: 10.1093/bja/aes306] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Carbamazepine and pregabalin have proven effects against neuropathic pain. Carbamazepine blocks voltage-dependent Na(+) channels, whereas pregabalin blocks voltage-dependent Ca(2+) channels. The authors hypothesized that the co-administration of these drugs would synergistically reduce neuropathic pain. METHODS Neuropathic pain was induced by L5 nerve ligation in Sprague-Dawley rats. To determine their ED(50) values, carbamazepine and pregabalin were orally administered at 0.3, 3, 10, or 30 mg kg(-1). The drugs were then co-administered at 0, 1/4×ED(50), 1/2×ED(50), 1.5×ED(50), and 2×ED(50) to determine the ED(50) and ED(75) values of the drugs in combination. Allodynia was determined using the von Frey hair test and dose-effect curves and isobolograms were used to investigate drug interactions. Levels of the acute reactive protein c-Fos in the dorsal horn were evaluated as an indicator of pathological nerve excitation. RESULTS At ED(50) levels, carbamazepine and pregabalin did not exhibit synergism, but doses higher than ED(75) were found to be synergistic. The combination index was 0.18 (strong synergy) and dose reductions were 35.7-fold for carbamazepine and 6.8-fold for pregabalin when co-administered when compared with a single administration at ED(75). The percentage allodynia relief was only 60% for carbamazepine and 80% for pregabalin by single administration, whereas their co-administration relieved allodynia by 100%. Furthermore, treatment decreased c-Fos expression in the dorsal horn, but expressional differences between animals treated with carbamazepine plus pregabalin were not significantly different from those treated with single drug. CONCLUSIONS Carbamazepine and pregabalin ameliorate neuropathic pain synergistically at higher doses.
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Moon JI, Kwon CHD, Joh JW, Choi GS, Jung GO, Kim JM, Shin M, Choi SJ, Kim SJ, Lee SK. Primary versus salvage living donor liver transplantation for patients with hepatocellular carcinoma: impact of microvascular invasion on survival. Transplant Proc 2012; 44:487-93. [PMID: 22410053 DOI: 10.1016/j.transproceed.2011.11.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Salvage liver transplantation (LT) has been proposed for patients with a small hepatocellular carcinoma (HCC) and preserved liver function. Few reports have been issued on salvage LT in a living-donor (LD) LT setting. Therefore, we performed this study to evaluate differences in tumor invasiveness and other risk factors on survival after salvage versus primary LDLT. METHODS Between September 1996 and December 2008, 324 patients with HCC underwent LT. We excluded 138 patient from the analysis, leaving 186 HCC patients for analysis, including 17 (9.1%) who had undergone earlier resection, the salvage LDLT cohort. The other 169 patients underwent primary LDLT. RESULTS Intrahepatic metastasis, Edmonson-Steiner histologic grade, microscopic vascular invasion, and preoperative serum alpha-fetoprotein levels significantly influenced tumor recurrence. Microscopic vascular invasion, intrahepatic metastasis, Edmonson-Steiner histologic grade, and treatment by salvage LDLT were significantly associated with poor patient survival univariate analysis. However, only microscopic vascular invasion was significant on multivariate analysis. The treatment modality (primary or salvage LDLT) was not observed to affect overall or disease-free survival significantly on multivariate analysis. Disease-free survival was significantly better in the primary than in the salvage LDLT group. Furthermore, patients in the primary LDLT group tended to show better survival. However, when stratified by the presence or absence of microscopic vascular invasion, no significant group difference was found for overall or disease-free survival among those without versus with microscopic vascular invasion. CONCLUSIONS Five-year overall survival after primary versus salvage LDLT were similar when differences in tumor pathologic features, such as microscopic vascular invasion, were taken into account. Multivariate analysis showed that the treatment itself was not a significant prognostic factor for survival.
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Jang M, Park Y, Hyun Y, Jun M, Choi SJ, Zyung T, Kim JD. Top-down processed silicon nanowires for thermoelectric applications. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2012; 12:3552-3554. [PMID: 22849166 DOI: 10.1166/jnn.2012.5580] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
50 nm wide n-type silicon nanowires have been manufactured by using a top-down process in order to investigate the thermoelectric properties of silicon nanowire. Nanowire test structures with platinum heaters and temperature sensors were fabricated. The extracted temperature coefficient of resistance (TCR) of the temperature sensors was 786.6 PPM/K. Also, the extracted Seebeck coefficient and power factor of the 50 nm wide phosphorus doped n-type silicon nanowires were -118 miroV/K and 2.16 mW x K(-2) x m(-1).
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Choi SJ, Moon DI, Duarte JP, Ahn JH, Choi YK. Physical observation of a thermo-morphic transition in a silicon nanowire. ACS NANO 2012; 6:2378-2384. [PMID: 22324745 DOI: 10.1021/nn2046295] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A thermo-morphic transition of a silicon nanowire (Si-NW) is investigated in vacuum and air ambients, and notable differences are found under each ambient. In the vacuum ambient, permanent electrical breakdown occurs as a result of the Joule self-heating arising from the applied voltage across both ends of the Si-NW. The resulting current abruptly declines from a maximum value at the breakdown voltage (V(BD)) to zero. In addition, the thermal conductivity of the Si-NW is extracted from the V(BD) values under the vacuum ambient and shows good agreement with previously reported results. While the breakdown of the Si-NW does not exhibit negative differential resistance under the vacuum ambient, it interestingly shows negative differential resistance with multiple resistances in the current-voltage characteristics under the air ambient, similar to the behavior of carbon nanotubes. This behavior is triggered by current-induced oxidation, which leads to the thermo-morphic transition observed by TEM analyses. Additionally, the current-induced oxidation is favorably applied to reduce the size of a Si-NW at a localized and designated point.
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