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Yu HC, Kumar SV, Cho SY, Kudo K, Takayama T, Oh JM, Jung H, Kim JG, Chung CM. Preparation and characterization of nanoporous thin films from fully aliphatic polyimides. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2011; 11:6141-6147. [PMID: 22121674 DOI: 10.1166/jnn.2011.4342] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Fully aliphatic polyimides (APIs) were prepared from rel-(1'R,3S5'S)-spiro[furan-3(2H),6'-[3]oxabicyclo[3.2.1]octane]-2,2',4',5(4H)-tetrone (DAn) as unsymmetrical spiro dianhydride, and either cis-trans-1,4-diaminocyclohexane (mix-DACH) or trans-1,4-diaminocyclohexane (trans-DACH) as diamine. Structure of all prepared monomers and polymers was confirmed via 1H-NMR and FT-IR. The solubility, optical transparency, and thermal properties of the full APIs were investigated. The solubility and decomposition temperature of the full APIs were found to be correlated with their intermolecular regularity confirmed via wide-angle X-ray diffraction (WAXD). Triblock copolyimides were synthesized through the incorporation of a thermally labile polymer, poly(propylene glycol) (PPG), into the full APIs, and their thermal properties were studied via thermogravimetric analysis (TGA). Nanoporous thin films of the full APIs were prepared via thermolysis of the labile block in the copolyimide films. Phase separation and nanopore formation in the copolymer films were confirmed via atomic force microscopy (AFM) and scanning electron microscopy (SEM), respectively. Nanoporous pores were successfully prepared inside the films.
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Kim JG, Song YK, Jo YH, Yu MR, Ju HW, Choi IH, Chung CM. A New Efficient Synthetic Method for 3-Iodothyronamine Involving Sonication and its Potent Hypothermic Efficacy. B KOREAN CHEM SOC 2011. [DOI: 10.5012/bkcs.2011.32.4.1131] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Ahn KD, Chung CM. Photoacid-generating sulfonyloxymaleimide polymers and their application to photoimaging. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/masy.19991420115] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Chung CM, Ahn KD. Synthesis and thermal modification of n
-substituted functional polymaleimides. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/masy.19971180165] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Ju H, So H, Ha K, Park K, Lee JW, Chung CM, Choi I. Sustained torpidity following multi-dose administration of 3-iodothyronamine in mice. J Cell Physiol 2011; 226:853-8. [DOI: 10.1002/jcp.22573] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Kumar SV, Yu HC, Choi J, Kudo K, Jang YH, Chung CM. Structure–property relationships for partially aliphatic polyimides. JOURNAL OF POLYMER RESEARCH 2010. [DOI: 10.1007/s10965-010-9513-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Cho SY, Kim JG, Chung CM. Photochemical crack healing in cinnamate-based polymers. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2010; 10:6972-6976. [PMID: 21137836 DOI: 10.1166/jnn.2010.2953] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Four kinds of cinnamate-type monomers were synthesized as healing agents. Photoirradiation of the monomers gave cyclobutane-containing crosslinked polymers via [2+2] cycloaddition. Cyclobutane cleavage upon cracking of the crosslinked polymers and re-cycloaddition of the cracked polymers were investigated by FT-IR spectroscopy. Photochemical crack healing was demonstrated by measurement of flexural strength of crosslinked, cracked, and healed polymers. It was observed that microcracks with width of 200 nm to 2 microm were healed by photoirradiation.
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Cho SY, Kim JG, Oh SY, Chung CM. Heat-induced crack healing in a perfluorocyclobutane-containing polymer. Macromol Res 2010. [DOI: 10.1007/s13233-009-0177-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Chung CM, Cho KW, Hong SW, Kim YJ, Chung TH. Feasibility of electroflotation to separate solids and liquid in an activated sludge process. ENVIRONMENTAL TECHNOLOGY 2009; 30:1565-1573. [PMID: 20184001 DOI: 10.1080/09593330903313802] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In this study, electroflotation (EF) has been applied as a secondary clarification in the activated sludge process to improve the efficiency of the solids-liquid separation, which is essential in maintaining effluent quality. The effects of sludge settleability were examined through a series of batch and semi-continuous experiments. The results of the batch experiments revealed that thickening efficiencies using EF were 2.6 to 9.2 times higher than those with gravity settling (GS). In addition, clarification efficiencies were not significantly influenced by sludge settling properties, as compared with GS as a control. In the semi-continuous EF experiments, the concentrations of solids in the float layer were maintained above 10 g L(-1) during flotation, regardless of variations in sludge settleability. Furthermore, the volumetric gas proportion in the float layer increased as the gas to solids (G/S) ratio rose. This allowed the float layer to be more stably suspended against gravity at the top of the reactor. Based on the results obtained from these batch and semi-continuous experiments, an anoxic/oxic (AO) reactor combined with EF clarifier remained in successful continuous operation for four months. In comparison with conventional AO processes using a GS clarifier, enhanced clarification and thickening efficiencies were achieved through the EF-AO system. In addition, higher mixed liquor suspended solids concentrations (averaging 5300 mg L(-1)) in the bioreactor (EF-AO) were maintained via the return of highly concentrated sludge (averaging 16,400 mg L(-1)) from the EF clarifier. These findings suggest that EF could be a promising and effective alternative for the solids-liquid separation of poorly settling sludge.
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Cho SY, Song YK, Kim JG, Oh SY, Chung CM. Photoconversion of o-hydroxycinnamates to coumarins and its application to fluorescence imaging. Tetrahedron Lett 2009. [DOI: 10.1016/j.tetlet.2009.06.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Chung CM, Cho SY, Kim JG, Oh SY. Preparation of unsaturated polyester–silica nanocomposites. J Appl Polym Sci 2007. [DOI: 10.1002/app.26943] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Chung CM, Lee JH, Cho SY, Kim JG, Moon SY. Preparation of porous thin films of a partially aliphatic polyimide. J Appl Polym Sci 2006. [DOI: 10.1002/app.23360] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Chung CM, Man C, Jin Y, Jin C, Guan XY, Wang Q, Wan TSK, Cheung ALM, Tsao SW. Amplification and overexpression of aurora kinase A (AURKA) in immortalized human ovarian epithelial (HOSE) cells. Mol Carcinog 2005; 43:165-74. [PMID: 15880741 DOI: 10.1002/mc.20098] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Immortalization is an early and essential step of human carcinogenesis. Amplification of chromosome 20q has been shown to be a common event in immortalized cells and cancers. We have previously reported that gain and amplification of chromosome 20q is a non-random and common event in immortalized human ovarian surface epithelial (HOSE) cells. The chromosome 20q harbors genes including TGIF2 (20q11.2-q12), AIB1 (20q12), PTPN1 (20q13.1), ZNF217 (20q13.2), and AURKA (20q13.2-q13.3), which were previously reported to be amplified and overexpressed in ovarian cancers. Some of these genes may be involved in immortalization of HOSE cells and represent crucial premalignant changes in ovarian surface epithelium. Investigation of the involvement of these genes was examined in four pairs of pre-crisis (preimmortalized) and post-crisis (immortalized) HOSE cells. Overexpression of AURKA (Aurora kinase A), also known as BTAK and STK15, by both real time-quantitative polymerase chain reaction (RT-QPCR) and Western blotting was detected in all the four immortalized HOSE cells examined while overexpression of AIB1 and ZNF217 was observed in two of four immortalized HOSE cells examined. Overexpression of TGIF2 and PTPN1 was not significant in our immortalized HOSE cell systems. The degree of overexpression of AURKA was shown to be closely associated with the amplification of chromosome 20q in immortalized HOSE cells. Fluorescence in situ hybridization (FISH) with labeled P1 artificial clone (PAC) confirmed the amplification of the chromosomal region (20q13.2-13.3) where AURKA resides. DNA amplification of AURKA was also confirmed using semi-quantitative PCR. Our study showed that amplification and overexpression of AURKA is a common and significant event during immortalization of HOSE cells and may represent an important premalignant change in ovarian carcinogenesis.
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Kim JG, Chung CM. Elution from light-cured dental composites: Comparison of trimethacrylate and dimethacrylate as base monomers. J Biomed Mater Res B Appl Biomater 2005; 72:328-33. [PMID: 15529333 DOI: 10.1002/jbm.b.30158] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The effect of the number of functional units on a monomer on the elution property of dental composites was first studied. Elution from a composite of a trifunctional methacrylate, 1,1,1-tris[4-(2'-hydroxy-3'-methacryloyloxypropoxy)phenyl]ethane (THMPE), was compared to that of bis-GMA, a typical difunctional base monomer in current dental composites. The degrees of cure and the water solubilities of composites prepared from the two kinds of methacrylates were measured. The concentration of unreacted methacrylates (base monomer and diluent) present in the photo-cured composites as well as the quantity of the methacrylates eluted into water (or 75%, volume fraction, of ethanol in water) from the composites were determined by high-performance liquid chromatography (HPLC). THMPE-based composites showed lesser amounts of residual and eluted methacrylates when compared with bis-GMA composites. This is attributed to the higher degree of functionality and larger molecular size of THMPE compared with those of bis-GMA.
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Moon SY, Chung CM. Two-component photoresists containing thermally crosslinkable photoacid generators. POLYM ENG SCI 2004. [DOI: 10.1002/pen.11252] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Chung CM, Kim MS, Kim JG, Jang DO. Synthesis and photopolymerization of trifunctional methacrylates and their application as dental monomers. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 2002; 62:622-7. [PMID: 12221711 DOI: 10.1002/jbm.10359] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
1,1,1-Tris[4-(2'-hydroxy-3'-methacryloyloxypropoxy)phenyl]ethane (THMPE) and tris[4-(2'-hydroxy-3'-methacryloyloxypropoxy)phenyl]methane (THMPM) were synthesized and evaluated as base monomers in a dental composite system. The photopolymerization reactivity of the trifunctional methacrylates was similar to that of conventional 2,2-bis[4-(2'-hydroxy-3'-methacryloyloxy-propoxy)phenyl]propane (bis-GMA). Of the three monomers (THMPE, THMPM, and bis-GMA), THMPE has the greatest molecular volume, and its composite showed the lowest photopolymerization shrinkage of the composites derived from the three monomers. The water-solubility values for the light-activated composite resins formulated with THMPE and THMPM were much lower than that for a control bis-GMA composite. The trimethacrylates were not leached out into water from their corresponding photo-cured composites whereas the difunctional bis-GMA was eluted from its composite. The water sorption and flexural strength of the composite resins based on THMPE and THMPM were comparable to those of the bis-GMA composite. THMPE is promising for application as a photocurable dental monomer because of its good polymerization reactivity along with relatively low curing shrinkage and water-solubility of its photo-cured composite.
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Oh SY, Park JK, Choi JW, Chung CM. Fabrication and Photodegradation Behavior of Photosensitive Polyimide LB Film. ACTA ACUST UNITED AC 2001. [DOI: 10.1080/10587250108030063] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Chung CM, Connors LH, Benson MD, Walsh MT. Biophysical analysis of normal transthyretin: implications for fibril formation in senile systemic amyloidosis. Amyloid 2001; 8:75-83. [PMID: 11409037 DOI: 10.3109/13506120109007348] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Transthyretin (TTR) is a plasma protein that transports thyroid hormone and retinol binding protein-vitamin A complex. Eighty-four variants of TTR have been identified and seventy-four are associated with familial amyloidotic polyneuropathy. Normal TTR is the major protein found in the fibrillar deposits in the heart at time of autopsy of individuals with senile systemic amyloidosis. The mechanism by which normally soluble TTR deposits as organ-damaging, insoluble, pathological fibrils late in life is unknown. Understanding the mechanism of fibrillogenesis of normal TTR is critical to the design of clinical treatments aimed at retardation, prevention, or reversal of fibril deposition. We have employed a biophysical approach to explore the hypothesis that an instability in a particular secondary or tertiary structure plays a role in the ability of normal TTR to form fibrils at physiological pH. Using far UV circular dichroic (CD) spectroscopy as a function of temperature we have identified simultaneous, cooperative, reversible structural changes in the beta-sheet and alpha-helical regions. The flexible short, surface-located loops undergo an irreversible conformational change at a lower temperature. Spectra before and after heating are different, particularly in the wavelength region associated with these loops, strongly suggesting that the major portion of TTR returns to its initial conformation while the loops do not. Near UV CD reveals partially reversible and irreversible changes in tertiary structure. Using calorimetry to directly measure the enthalpy associated with these changes, two peaks are observed, with further analysis suggesting conformational intermediates. Precipitates from heated samples reveal pre-fibrillar morphology by negative stain electron microscopy. These biophysical studies suggest that heat-induced conformational rearrangements enable normal TTR to assemble into pre-fibrils at physiological pH.
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Jang DO, Kim J, Cho DH, Chung CM. Radical deoxygenation of alcohols via their trifluoroacetate derivatives with diphenylsilane. Tetrahedron Lett 2001. [DOI: 10.1016/s0040-4039(00)02184-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Jang DO, Cho DH, Chung CM. 1-Ethylpiperidium Hypophosphite: A Practical Mediator for Radical Carbon-Carbon Bond Formation. Synlett 2001. [DOI: 10.1055/s-2001-18781] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Moon SY, Chung CM. THREE-COMPONENT PHOTORESISTS CONTAINING VINYL ETHER CROSSLINKING AGENTS. JOURNAL OF MACROMOLECULAR SCIENCE PART A-PURE AND APPLIED CHEMISTRY 2001. [DOI: 10.1081/ma-100103346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Chung CM, Kim JG, Choi JH. Synthesis and photopolymerization of dicarboxylic acid dimethacrylates and their application as dental monomers. J Appl Polym Sci 2000. [DOI: 10.1002/1097-4628(20000822)77:8<1802::aid-app17>3.0.co;2-m] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Chung CM, Ahn KD. Photochemical acid generation from copolymers based on camphorsulfonyloxymaleimide and acidolytic deprotection. REACT FUNCT POLYM 1999. [DOI: 10.1016/s1381-5148(98)00007-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ahn KD, Chung CM, Kim YH. Synthesis and photopolymerization of multifunctional methacrylates derived from Bis-GMA for dental applications. J Appl Polym Sci 1999. [DOI: 10.1002/(sici)1097-4628(19990321)71:12<2033::aid-app13>3.0.co;2-i] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Chung CM, Kim JG, Choi JH. Photopolymerization Behavior of a Carboxylic Acid Dimetharylate and Its Application as a Dental Monomer. J PHOTOPOLYM SCI TEC 1999. [DOI: 10.2494/photopolymer.12.401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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