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Yoon T, Kim JH, Choi JH, Jung DY, Park IJ, Choi SY, Cho NS, Lee JI, Kwon YD, Cho S, Kim TS. Healing Graphene Defects Using Selective Electrochemical Deposition: Toward Flexible and Stretchable Devices. ACS NANO 2016; 10:1539-45. [PMID: 26715053 DOI: 10.1021/acsnano.5b07098] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Graphene produced by chemical-vapor-deposition inevitably has defects such as grain boundaries, pinholes, wrinkles, and cracks, which are the most significant obstacles for the realization of superior properties of pristine graphene. Despite efforts to reduce these defects during synthesis, significant damages are further induced during integration and operation of flexible and stretchable applications. Therefore, defect healing is required in order to recover the ideal properties of graphene. Here, the electrical and mechanical properties of graphene are healed on the basis of selective electrochemical deposition on graphene defects. By exploiting the high current density on the defects during the electrodeposition, metal ions such as silver and gold can be selectively reduced. The process is universally applicable to conductive and insulating substrates because graphene can serve as a conducting channel of electrons. The physically filled metal on the defects improves the electrical conductivity and mechanical stretchability by means of reducing contact resistance and crack density. The healing of graphene defects is enabled by the solution-based room temperature electrodeposition process, which broadens the use of graphene as an engineering material.
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Tae Lim J, Lee H, Cho H, Kwon BH, Sung Cho N, Kuk Lee B, Park J, Kim J, Han JH, Yang JH, Yu BG, Hwang CS, Chu Lim S, Lee JI. Flexion bonding transfer of multilayered graphene as a top electrode in transparent organic light-emitting diodes. Sci Rep 2015; 5:17748. [PMID: 26626439 PMCID: PMC4667220 DOI: 10.1038/srep17748] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 11/05/2015] [Indexed: 11/09/2022] Open
Abstract
Graphene has attracted considerable attention as a next-generation transparent conducting electrode, because of its high electrical conductivity and optical transparency. Various optoelectronic devices comprising graphene as a bottom electrode, such as organic light-emitting diodes (OLEDs), organic photovoltaics, quantum-dot LEDs, and light-emitting electrochemical cells, have recently been reported. However, performance of optoelectronic devices using graphene as top electrodes is limited, because the lamination process through which graphene is positioned as the top layer of these conventional OLEDs is a lack of control in the surface roughness, the gapless contact, and the flexion bonding between graphene and organic layer of the device. Here, a multilayered graphene (MLG) as a top electrode is successfully implanted, via dry bonding, onto the top organic layer of transparent OLED (TOLED) with flexion patterns. The performance of the TOLED with MLG electrode is comparable to that of a conventional TOLED with a semi-transparent thin-Ag top electrode, because the MLG electrode makes a contact with the TOLED with no residue. In addition, we successfully fabricate a large-size transparent segment panel using the developed MLG electrode. Therefore, we believe that the flexion bonding technology presented in this work is applicable to various optoelectronic devices.
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Lee KM, Kim H, Nemeno JG, Yang W, Yoon J, Lee S, Lee JI. Natural cardiac extracellular matrix sheet as a biomaterial for cardiomyocyte transplantation. Transplant Proc 2015; 47:751-6. [PMID: 25891725 DOI: 10.1016/j.transproceed.2014.12.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 12/31/2014] [Indexed: 11/26/2022]
Abstract
Cardiovascular diseases associated with myocardial infarction are among the major causes of death worldwide due to the limited regenerative capacity of cardiac tissues. Although various approaches, such as biosynthetic biomaterials, have been developed to promote postinfarction cardiac regeneration, a number of limitations, including the immune complications caused by biodegradation of these scaffolds and insufficient cell migration, need to be overcome prior to their clinical application. Hence, the development of natural biomaterials to support myocardial regeneration is crucial. Here, we investigated the effects of a natural biomaterial, cardiac extracellular matrix (ECM) on the proliferation and maintenance of cardiomyocytes in order to assess its suitability for cardiomyocyte expansion. The ECM components not only provide mechanical support, but also induce and preserve the required phenotypic and functional characteristics of the cells. We prepared ECM sheets from decellularized cardiac sections. Cardiomyocytes were then cultured with and without these cardiac ECM sheets. We compared the proliferation rates and phenotypes, and cardiac gene and protein expression, of the cultured cardiomyocytes by automatic cell counting and the MTT assay, microscopy, and RT-PCR and western blotting, respectively. The cardiomyocytes cultured with the natural cardiac ECM sheets exhibited higher proliferation rates and cardiac gene and protein expression than those cultured without the ECM sheets. Our results demonstrate that the ECM sheets are suitable for use in cardiomyocyte transplantation and can provide a novel in vitro model for investigating cell and ECM interactions. We hypothesize that these ECM sheets can be used in the future to improve cardiac transplantation strategies.
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Chung J, Cho H, Koh TW, Lee J, Kim E, Lee J, Lee JI, Yoo S. Towards highly efficient and highly transparent OLEDs: advanced considerations for emission zone coupled with capping layer design. OPTICS EXPRESS 2015; 23:27306-27314. [PMID: 26480391 DOI: 10.1364/oe.23.027306] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Strategies to achieve efficient transparent organic light-emitting diodes (TrOLEDs) are presented. The emission zone position is carefully adjusted by monitoring the optical phase change upon reflection from the top electrode, which is significant when the thickness of the capping layer changes. With the proposed design strategy, external quantum efficiency and transmittance values as high as 15% and 80% are demonstrated simultaneously. The effect of surface plasmon polariton (SPP) loss from thin metal electrodes is also taken into account to correctly describe the full scaling behavior of the efficiency of TrOLEDs over key optical design parameters.
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Park SK, Kwark YJ, Moon J, Joo CW, Yu B, Lee JI. Finely Formed, Kinetically Modulated Wrinkle Structures in UV-Crosslinkable Liquid Prepolymers. Macromol Rapid Commun 2015; 36:2006-11. [DOI: 10.1002/marc.201500370] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 08/12/2015] [Indexed: 11/10/2022]
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Mizuno M, Takebe T, Kobayashi S, Kimura S, Masutani M, Lee S, Jo YH, Lee JI, Taniguchi H. Elastic cartilage reconstruction by transplantation of cultured hyaline cartilage-derived chondrocytes. Transplant Proc 2015; 46:1217-21. [PMID: 24815164 DOI: 10.1016/j.transproceed.2013.12.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 11/23/2013] [Accepted: 12/10/2013] [Indexed: 11/18/2022]
Abstract
Current surgical intervention of craniofacial defects caused by injuries or abnormalities uses reconstructive materials, such as autologous cartilage grafts. Transplantation of autologous tissues, however, places a significant invasiveness on patients, and many efforts have been made for establishing an alternative graft. Recently, we and others have shown the potential use of reconstructed elastic cartilage from ear-derived chondrocytes or progenitors with the unique elastic properties. Here, we examined the differentiation potential of canine joint cartilage-derived chondrocytes into elastic cartilage for expanding the cell sources, such as hyaline cartilage. Articular chondrocytes are isolated from canine joint, cultivated, and compared regarding characteristic differences with auricular chondrocytes, including proliferation rates, gene expression, extracellular matrix production, and cartilage reconstruction capability after transplantation. Canine articular chondrocytes proliferated less robustly than auricular chondrocytes, but there was no significant difference in the amount of sulfated glycosaminoglycan produced from redifferentiated chondrocytes. Furthermore, in vitro expanded and redifferentiated articular chondrocytes have been shown to reconstruct elastic cartilage on transplantation that has histologic characteristics distinct from hyaline cartilage. Taken together, cultured hyaline cartilage-derived chondrocytes are a possible cell source for elastic cartilage reconstruction.
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Hahn SH, Lee J, Chu HY, Lee JI, Lee YJ, Hwang J, Shin SC, Kim YH. New Blue Emitting Material with Asymmetric Limb Structure. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2015; 15:355-359. [PMID: 26328360 DOI: 10.1166/jnn.2015.8820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The new assymmetric limb-structured blue light emitting material, composed of anthracene main core, naphthalene units at 9, 10-position of anthracene and xylene units at 2,3-positon of anthracene, was designed and synthesized. The three-dimensional structure from theoretical calculation was characterized to elucidate non-copolar structure with inhibited intermolecular interaction. The limb-structured blue material was thermally stable up to 373 degrees C with T(g) of 143 degrees C. ITO/TAPC/CBP (3% BMPNA)/Bphen/LiF/Al device exhibits the maximum quantum efficiency of 3.42% and maximum current efficiency of 3.07 cd/A with deep blue emission of (0.141, 0.115) CIE coordinates.
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Kim JY, Joo CW, Lee J, Woo JC, Oh JY, Baek NS, Chu HY, Lee JI. Save energy on OLED lighting by a simple yet powerful technique. RSC Adv 2015. [DOI: 10.1039/c4ra10434j] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In order to reduce power consumption in OLED lighting, polymeric lighting extraction films were integrated directly on the backside of green emissive bottom-emitting OLED glass substrates. The luminous efficacy and external quantum efficiency were improved by up to 50%.
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Cho DH, Shin JW, Joo CW, Lee J, Park SK, Moon J, Cho NS, Chu HY, Lee JI. Light diffusing effects of nano and micro-structures on OLED with microcavity. OPTICS EXPRESS 2014; 22 Suppl 6:A1507-A1518. [PMID: 25607307 DOI: 10.1364/oe.22.0a1507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We examined the light diffusing effects of nano and micro-structures on microcavity designed OLEDs. The results of FDTD simulations and experiments showed that the pillar shaped nano-structure was more effective than the concave micro-structure for light diffusing of microcavity OLEDs. The sharp luminance distribution of the microcavity OLED was changed to near Lambertian luminance distribution by the nano-structure, and light diffusing effects increased with the height of the nano-structure. Furthermore, the nano-structure has advantages including light extraction of the substrate mode, reproducibility of manufacturing process, and minimizing pixel blur problems in an OLED display panel. The nano-structure is a promising candidate for a light diffuser, resolving the viewing angle problems in microcavity OLEDs.
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Choi H, Choi JS, Kim JS, Choe JH, Chung KH, Shin JW, Kim JT, Youn DH, Kim KC, Lee JI, Choi SY, Kim P, Choi CG, Yu YJ. Flexible and transparent gas molecule sensor integrated with sensing and heating graphene layers. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2014; 10:3685-91. [PMID: 24832822 DOI: 10.1002/smll.201400434] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 04/01/2014] [Indexed: 05/13/2023]
Abstract
Graphene leading to high surface-to-volume ratio and outstanding conductivity is applied for gas molecule sensing with fully utilizing its unique transparent and flexible functionalities which cannot be expected from solid-state gas sensors. In order to attain a fast response and rapid recovering time, the flexible sensors also require integrated flexible and transparent heaters. Here, large-scale flexible and transparent gas molecule sensor devices, integrated with a graphene sensing channel and a graphene transparent heater for fast recovering operation, are demonstrated. This combined all-graphene device structure enables an overall device optical transmittance that exceeds 90% and reliable sensing performance with a bending strain of less than 1.4%. In particular, it is possible to classify the fast (≈14 s) and slow (≈95 s) response due to sp(2) -carbon bonding and disorders on graphene and the self-integrated graphene heater leads to the rapid recovery (≈11 s) of a 2 cm × 2 cm sized sensor with reproducible sensing cycles, including full recovery steps without significant signal degradation under exposure to NO2 gas.
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Huh JW, Shin JW, Cho DH, Moon J, Joo CW, Park SK, Hwang J, Cho NS, Lee J, Han JH, Chu HY, Lee JI. A randomly nano-structured scattering layer for transparent organic light emitting diodes. NANOSCALE 2014; 6:10727-10733. [PMID: 25099663 DOI: 10.1039/c4nr01520g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A random scattering layer (RSL) consisting of a random nano-structure (RNS) and a high refractive index planarization layer (HRI PL) is suggested and demonstrated as an efficient internal light-extracting layer for transparent organic light emitting diodes (TOLEDs). By introducing the RSL, a remarkable enhancement of 40% and 46% in external quantum efficiency (EQE) and luminous efficacy (LE) was achieved without causing deterioration in the transmittance. Additionally, with the use of the RSL, the viewing angle dependency of EL spectra was reduced to a marginal degree. The results were interpreted as the stronger influence of the scattering effect over the microcavity. The RSL can be applied widely in TOLEDs as an effective light-extracting layer for extracting the waveguide mode of confined light at the indium tin oxide (ITO)/OLED stack without introducing spectral changes in TOLEDs.
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Mizukami K, Yabuki A, Endoh D, Chang HS, Lee KW, Nakayama M, Kushida K, Kohyama M, Lee JI, Yamato O. Investigation of parallel and simultaneous selection for collie eye anomaly and ivermectin toxicosis. Vet Rec 2014; 175:174. [PMID: 24939474 DOI: 10.1136/vr.102015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Schreiner A, Hargarter L, Hitschfield K, Lee JI, Lenskaya I, Sulaiman AH, Diels J. Clinical effectiveness and resource utilization of paliperidone ER for schizophrenia: Pharmacoepidemiologic International Longitudinal Antipsychotic Registry (PILAR). Curr Med Res Opin 2014; 30:1279-89. [PMID: 24597755 DOI: 10.1185/03007995.2014.898630] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVE To document prescribing patterns in clinical practice and assess long-term outcomes related to initiation of paliperidone ER and other oral antipsychotics among patients with schizophrenia in a naturalistic setting. RESEARCH DESIGN AND METHODS An international, non-interventional, naturalistic study of adult patients (≥18 years) with schizophrenia. Patients were assigned to the relevant treatment group (paliperidone ER or 'all other oral antipsychotics') after switching to, or initiating, oral antipsychotic treatment. Retrospective 12 month data collection was followed by 12 month prospective data collection, with 3-monthly assessments. The primary endpoint was time to all-cause discontinuation of new medication. Secondary endpoints included Clinical Global Impression-Severity (CGI-S) score, Clinical Global Impression-Schizophrenia (CGI-SCH) score, Personal and Social Performance (PSP) score, health-related quality of life (HR-QoL) and quality of sleep, evaluation of healthcare resource utilization and patient's treatment satisfaction. RESULTS A total of 4051 patients were included in the intent-to-treat (ITT) analysis set. All-cause study discontinuation rates were comparable between the paliperidone ER group (16.8%) and the 'all other oral antipsychotics' group (15.5%). There was no difference in the time to discontinuation of newly initiated antipsychotic treatments between paliperidone ER and 'all other oral antipsychotics' groups. Paliperidone ER was associated with greater improvements from baseline to endpoint in both the PSP scale score (+14.2 vs +13.1, p = 0.041) and the physical component of quality of life (SF-12 Physical scores; +3.9 vs +2.9, p = 0.003) compared to 'all other oral antipsychotics'. Improvements in mean CGI-S score, CGI-SCH score, HR-QoL, quality of sleep and daytime drowsiness, as well as patients' treatment satisfaction were comparable between treatment groups. The incidence of adverse events was comparable between groups. CONCLUSIONS This study provides valuable data on the prescribing habits and treatment outcomes associated with use of paliperidone ER in everyday clinical practice, and supports previous findings of the favorable functional improvement and treatment satisfaction associated with paliperidone ER. CLINICAL TRIAL REGISTRATION NCT00696813; R076477SCH4015 (Register of German Association of Research-based Pharmaceutical Companies [VFA] http://www.vfa.de/de/arzneimittel-forschung/datenbanken-zu-arzneimitteln/nisdb).
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Shin JW, Cho DH, Moon J, Joo CW, Lee J, Huh JW, Park SK, Han JH, Cho NS, Hwang J, Chu HY, Lee JI. Random nanostructure scattering layer for suppression of microcavity effect and light extraction in OLEDs. OPTICS LETTERS 2014; 39:3527-3530. [PMID: 24978528 DOI: 10.1364/ol.39.003527] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In this study, we investigated the effect of a random nanostructure scattering layer (RSL) on the microcavity and light extraction in organic light emitting diodes (OLEDs). In the case of the conventional OLED, the optical properties change with the thickness of the hole transporting layer (HTL) because of the presence of a microcavity. However, OLEDs equipped with the an RSL showed similar values of external quantum efficiency and luminous efficacy regardless of the HTL thickness. These phenomena can be understood by the scattering effect because of the RSL, which suppresses the microcavity effect and extracts the light confined in the device. Moreover, OLEDs with the RSL led to reduced spectrum and color changes with the viewing angle.
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Noh H, Lee JI. Current and potential therapeutic strategies for mucopolysaccharidoses. J Clin Pharm Ther 2014; 39:215-24. [PMID: 24612142 DOI: 10.1111/jcpt.12136] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2013] [Accepted: 01/08/2014] [Indexed: 12/22/2022]
Abstract
WHAT IS KNOWN AND OBJECTIVE Mucopolysaccharidoses (MPSs) are a group of rare inherited metabolic diseases caused by genetic defects in the production of lysosomal enzymes. MPSs are clinically heterogeneous and are characterized by progressive deterioration in visceral, skeletal and neurological functions. This article aims to review the classification and pathophysiology of MPSs and discuss current therapies and new targeted agents under development. METHODS A Medline search through PubMed was performed for relevant articles and treatment guidelines on MPSs published in English for years 1970 to September of 2013 inclusive. The references listed in the identified articles, prescribing information of the drugs approved for the treatment of MPSs, as well as recent clinical trial information posted on Clinicaltrials.gov website, were reviewed. RESULTS AND DISCUSSION Until recently, supportive care was the only option available for the management of MPSs. In the early 2000s, enzyme replacement therapy (ERT) was approved by the United States Food and Drug Administration (FDA) for the treatment of MPS I, II and VI. Clinical trials of ERT showed substantial improvements in patients' somatic symptoms; however, no benefit was found in the neurological symptoms because the enzymes do not readily cross the blood-brain barrier (BBB). Haematopoietic stem cell transplantation (HSCT), another potentially curative treatment, is not routinely advocated in clinical practice due to its high risk profile and lack of evidence for efficacy, except in preserving cognition and prolonging survival in young patients with severe MPS I. In recent years, substrate reduction therapy (SRT) and gene therapy have been rapidly gaining greater recognition as potential therapeutic avenues. WHAT IS NEW AND CONCLUSION Enzyme replacement therapy (ERT) is effective for the treatment of many somatic symptoms, particularly walking ability and respiratory function, and remains the mainstay of MPS treatment. The usefulness of HSCT has not been established adequately for most MPSs. Although still under investigation, SRT and gene therapy are promising MPS treatments that may prevent the neurodegeneration not affected by ERT.
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Ju MK, Jeong JH, Lee JI, Kim YS, Kim MS. Proliferation and functional assessment of pseudo-islets with the use of pancreatic endocrine cells. Transplant Proc 2014; 45:1885-8. [PMID: 23769063 DOI: 10.1016/j.transproceed.2012.12.029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 12/31/2012] [Indexed: 11/26/2022]
Abstract
Many obstacles beset islet transplantation, particularly insufficient tissue mass. Previously, we reported production of pseudo-islets. In addition, there have been reports in which coculture with pancreatic islet and bone marrow mesenchymal stem cells (BMSCs) demonstrated positive effects on pancreatic islet function. The purpose of this study was to perform morphologic and functional evaluations of pancreatic pseudo-islets cocultured with BMSCs. Pancreatic endocrine cells (PECs) were collected with a previously reported method; bone marrow was aspirated from the rat femur. Subsequently, PECs and BMSCs cocultured at high density on low-cell-binding culture dishes kept suspended by shaking. The functionality and characteristics of the mixed cell complexes were evaluated by glucose challenge, insulin enzyme-linked immunosorbent assay, reverse-transcription polymerase chain reaction, and immunohistochemistry. Through expansion for 2 weeks in continuous culture passages, ∼1 million PECs were recovered after aggregation. They presented spherical shapes and sizes similar to naïve islets, according to phase-contrast microscopy. The spheroid aggregates of pancreatic islet cells and BMSCs showed fortified functions and maintained viability. In conclusion, PECs served as a cell source for pseudo-islets, which were both morphologically and genetically similar to naïve islets. We also suggest a manufacturing method for mixed cellular complexes from 2 different origins that can improve secretion ability and cell differentiation.
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Kim JW, Jang JH, Oh MC, Shin JW, Cho DH, Moon JH, Lee JI. FDTD analysis of the light extraction efficiency of OLEDs with a random scattering layer. OPTICS EXPRESS 2014; 22:498-507. [PMID: 24515010 DOI: 10.1364/oe.22.000498] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The light extraction efficiency of OLEDs with a nano-sized random scattering layer (RSL-OLEDs) was analyzed using the Finite Difference Time Domain (FDTD) method. In contrast to periodic diffraction patterns, the presence of an RSL suppresses the spectral shift with respect to the viewing angle. For FDTD simulation of RSL-OLEDs, a planar light source with a certain spatial and temporal coherence was incorporated, and the light extraction efficiency with respect to the fill factor of the RSL and the absorption coefficient of the material was investigated. The design results were compared to the experimental results of the RSL-OLEDs in order to confirm the usefulness of FDTD in predicting experimental results. According to our FDTD simulations, the light confined within the ITO-organic waveguide was quickly absorbed, and the absorption coefficients of ITO and RSL materials should be reduced in order to obtain significant improvement in the external quantum efficiency (EQE). When the extinction coefficient of ITO was 0.01, the EQE in the RSL-OLED was simulated to be enhanced by a factor of 1.8.
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Lee J, Cho H, Koh TW, Yun C, Hofmann S, Lee JH, Kim YH, Lüssem B, Lee JI, Leo K, Gather MC, Yoo S. Enhanced and balanced efficiency of white bi-directional organic light-emitting diodes. OPTICS EXPRESS 2013; 21:28040-28047. [PMID: 24514317 DOI: 10.1364/oe.21.028040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report on the characteristics of enhanced and balanced white-light emission from bi-directional organic light-emitting diodes (BiOLEDs) enabled by the introduction of micro-cavity effects. The insertion of an additional metal layer between the indium tin oxide anode and the hole transporting layer results in similar light output of our BiOLEDs in both top and bottom direction and in reduced distortion of the electroluminescence spectrum. Furthermore, we find that by utilizing MC effects, the overall current efficiency can be improved by 26.2% compared to that of a conventional device.
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Yeo JE, Nam BM, Yang W, Jo YH, Lee S, Nemeno JG, Kiml BY, Koh YG, Lee JI. Fragmin/protamine microparticle carriers as a drug repositioning strategy for cell transplantation. Transplant Proc 2013; 45:3122-6. [PMID: 24157048 DOI: 10.1016/j.transproceed.2013.08.086] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND The importance of drug repositioning has been gaining attention in the last few years, allowing existing pharmaceutical products to be reevaluated for potential alternative therapeutic applications. The purpose of this study was to evaluate the effects of fragmin/protamine microparticles (F/P MPs) on cell aggregates under the concept of drug repositioning. METHODS Mesenchymal stem cells (MSCs) and embryonic rat heart-derived cardiac H9C2 cells were mixed with D-PBS, basal medium, fragmin, protamine, and F/P MPs to manufacture aggregates intended for cell transplantation. To evaluate their adhesive properties as cell carriers, we injected combinations of MSC aggregates into cartilage tissue, observing their leakage from the implantation site. RESULTS Our data demonstrated that MSCs and H9C2 cells mixed with F/P MPs rapidly produced large, viscous cellular aggregates. F/P MPs were bound to the surface of MSCs and H9C2 cells; thus, F/P MPs induced the formation of F/P MP-cell aggregates. Cell aggregates were prevented from leaking from the transplanted site. CONCLUSION Aggregation induced by F/P MPs may improve the efficiency of cell therapy, a novel method for transplantation.
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Kim SI, Kim BH, Chang I, Lee JI, Kim JL, Pradhan AS. Response of six neutron survey meters in mixed fields of fast and thermal neutrons. RADIATION PROTECTION DOSIMETRY 2013; 156:518-524. [PMID: 23620566 DOI: 10.1093/rpd/nct103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Calibration neutron fields have been developed at KAERI (Korea Atomic Energy Research Institute) to study the responses of commonly used neutron survey meters in the presence of fast neutrons of energy around 10 MeV. The neutron fields were produced by using neutrons from the (241)Am-Be sources held in a graphite pile and a DT neutron generator. The spectral details and the ambient dose equivalent rates of the calibration fields were established, and the responses of six neutron survey meters were evaluated. Four single-moderator-based survey meters exhibited an under-responses ranging from ∼9 to 55 %. DINEUTRUN, commonly used in fields around nuclear reactors, exhibited an over-response by a factor of three in the thermal neutron field and an under-response of ∼85 % in the mixed fields. REM-500 (tissue-equivalent proportional counter) exhibited a response close to 1.0 in the fast neutron fields and an under-response of ∼50 % in the thermal neutron field.
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Jeon YB, Park KY, Moon JK, Park CH, Choi CH, Lee JI. Dobutamine induced cardiogenic shock due to systolic anterior motion after mitral valve repair. Anaesth Intensive Care 2013; 41:551-552. [PMID: 23808519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
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Kang WG, Choi JH, Jeon EJ, Lee JI, Kim HJ, Kim SK, Kim YD, Lee JH, Ma KJ, Myung SS, So JH. Ultra-low gamma-ray measurement system for neutrinoless double beta decay. Appl Radiat Isot 2013; 81:290-3. [PMID: 23726518 DOI: 10.1016/j.apradiso.2013.03.057] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 03/14/2013] [Indexed: 11/17/2022]
Abstract
An experiment for the detection of 0νβ(+)/EC and 0νEC/EC in 92Mo nuclei has been carried out with a scintillating crystal, CaMoO4, in coincidence with the HPGe detector. We study the background events inside the event selection window for 0ν β(+)/EC decays of CaMoO4 detector. For 51.2 days of data taking period, we didn't observe any event in the neutrinoless EC/EC decay event window. The (92)Mo 0νβ(+)/EC decay half-life limit was set to 0.61×10(20) years with a 90% confidence by method of Feldman and Cousins. This ultra-low gamma ray measurement utilizing coincidence technique can be used for the resonant EC/EC decay process of some nuclei which is potentially important for neutrinoless double beta decay process.
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Lee JI, Jeon WJ, Suh DH, Park JH, Lee JM, Park JW. Reply to Drs Fusetti, Garavaglia and Thébaud. J Hand Surg Eur Vol 2013; 38:577-8. [PMID: 23844419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Moon J, Park JA, Lee SJ, Lee JI, Zyung T, Shin EC, Lee JS. A physicochemical mechanism of chemical gas sensors using an AC analysis. Phys Chem Chem Phys 2013; 15:9361-74. [PMID: 23660648 DOI: 10.1039/c3cp44684k] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electrical modeling of the chemical gas sensors was successfully applied to TiO2 nanofiber gas sensors by developing an equivalent circuit model where the junction capacitance as well as the resistance can be separated from the comparable stray capacitance. The Schottky junction impedance exhibited a characteristic skewed arc described by a Cole-Davidson function, and the variation of the fit and derived parameters with temperature, bias, and NO2 gas concentration indicated definitely a physicochemical sensing mechanism based on the Pt|TiO2 Schottky junctions against the conventional supposition of the enhanced sensitivity in nanostructured gas sensors with high grain boundary/surface area. Analysis on a model Pt|TiO2|Pt structure also confirmed the characteristic impedance response of TiO2 nanofiber sensors.
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Xu F, Kim HU, Mi D, Lim JM, Hwang JH, Cho NS, Lee JI, Hwang DH. Synthesis and Characterization of Iridium-Containing Green Phosphorescent Polymers for PLEDs. B KOREAN CHEM SOC 2013. [DOI: 10.5012/bkcs.2013.34.2.399] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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