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1P-8 Synthesis and characterization of new flame-retarding epoxy resin
( Mai Toan ),신승한,김상용 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1
Epoxy resins have been widely used as coatings, adhesives, and structural composites as well as electronic materials due to their superior mechanical properties, excellent thermal resistance and good process ability; diglycidyl ather of bisphenol A (BGEBA), comes from a fossil based materials, which presents the most common of the epoxy precursors in the world. Due to the limitation on environmental issue, fossil based materials should be replaced by bio-based one. Additionally, the low flame-retardancy of epoxy resin limits its use in may fields; there are many research groups effort to introduce flame resistance epoxy based polymer. In this work, levulinic acid was used as renewable resource to prepare and epoxy monomer and flame retardant reactivity. The new flame retarding epoxy resin was synthesized via 5-steps reaction. The resulted epoxy was cured with commercial curing agent isophorondiamine (IPDA) and some basic properties of final polymer were characterized.
Synthesis of new photocurable resin based on furanic core for replacing Bis-GMA
( Mai Toan ),신승한 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0
Bisphenol-A (BPA) has been widely used for plastics and epoxy resins because it provides clearness and toughness. However, there are many side effects for human heath, especially for children, because of its hormone-like properties. Therefore, some products based on BPA need to be replaced by others human friendly materials such as materials come from biomass. One of the most promising materials can replace BPA is biomass derived furanic core compounds. In this study, we synthesized and characterized new acrylate photocurable binder based on furanic core. We also compared its curing behaviour and mechanical properties with BisGMA (bisphenol-A-glycidyl dimethacrylate) that has been used for several decades as a photocurable binder.
Synthesis of new-flame retardant epoxy resin based on levulinic acid
( Mai Toan ),신승한 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
During the last decades, there have been many efforts intend to find renewable resources that can alternate the oil-based materials due to the depletion of petroleum reservoirs and environmental issue. Among polymetric materials, epoxy resins are an important class of thermosetting polymers due to there excellent mechanical properties and thermal resistance, there fore they have many applications on adhesives, coatings, electronic component and so on. In this work, levulinic acid was used as a renewable resource to prepare an epoxy monormer and phosphorus containing functional group was incorporated to enhance its flame resistance. The new flame retardant epoxy resin was synthesized via five-step reaction and its structure was characterized by <sup>1</sup>H-NMR, <sup>13</sup>C-NMR and 31P-NMR.
Synthesis of new photocuring resins based on Isorsobide core for replacing BisGMA
( Mai Toan ),신승한 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0
BisGMA ((Bisphenol”A”-bis-(2-hydroxypropyl) methacrylate) have been used for several decades as a photo-curing resin. However, due to the human health risk of Bis-Phenol A release so BisGMA need to be replaced by others human friendly materials. Carbohydrate biomass is most abundant and widely used feedstock and many efforts were made to transform carbohydrate into useful chemicals. In particular, isosorbide from biomass attracts attention as a promising platform to replace petroleum-based bisphenol A. New photo-curing resin with isosorbide backbone was synthesized and characterized, which have potential for replacing BisGMA.
Synthesis of New Furan based methacrylate for replacing Bis-GMA
( Mai Toan ),신승한 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0
BisGMA (Bisphenol”A”-bis-(2-hydroxypropyl) methacrylate) is one of the most famous curing resins and widely uses for many applications,especially for dental restorative material. However, there are many side effects of the release of Bis-phenol A in the human heath so BisGMA need to be replaced by others human friendly materials. Furan, which has origin from biomass, has emerged as a potential material that can replace aromatic core. New acrylate photo curing resins based on furanic core was synthesized and characterized, which have potential for replacing BisGMA
치과소재로의 적용을 위한 isosorbide 기반 사관능성 광경화 소재의 합성 및 물성 평가
( Mai Toan ),김영재,김보라,조진구,신승한 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1
현재 치과용 소재로 널리 사용되고 있는 비스페놀A 기반 물질인 BisGMA를 대체하기 위한 연구가 활발히 진행되고 있다. 특히, 바이오매스 유래 sugar-diol인 isosorbide에 dimethacrylate를 도입한 IsoGMA는 인체무해성으로 인해 BisGMA의 잠재적 대체물질로 각광받고 있다. 그러나 IsoGMA는 기존 BisGMA에 비해 기계적 강도와 흡습성이 낮다는 문제점이 있어 이러한 단점을 보안하기 위하여 본 연구에서는 IsoGMA에 dimethacrylate를 추가로 도입하여 새로운 형태의 사관능성 광경화 소재를 합성하였다. 사관능성 광경화 소재의 첨가를 통한 IsoGMA의 기계적 물성, 수축율 및 흡습성에 대한 변화를 고찰하였다.
Protein kinase Cδ knockout mice are protected from cocaine-induced hepatotoxicity
Mai, Huynh Nhu,Lee, Sung Hoon,Sharma, Garima,Kim, Dae-Joong,Sharma, Naveen,Shin, Eun-Joo,Pham, Duc Toan,Trinh, Quynh Dieu,Jang, Choon-Gon,Nah, Seung-Yeol,Jeong, Ji Hoon,Kim, Hyoung-Chun Elsevier 2019 Chemico-biological interactions Vol.297 No.-
<P><B>Abstract</B></P> <P>We investigated whether protein kinase Cδ (PKCδ) mediates cocaine-induced hepatotoxicity in mice. Cocaine treatment (60 mg/kg, i.p.) significantly increased cleaved PKCδ expression in the liver of wild-type (WT) mice, and led to significant increases in oxidative parameters (i.e., reactive oxygen species, 4-hydroxylnonenal and protein carbonyl). These cocaine-induced oxidative burdens were attenuated by pharmacological (i.e., rottlerin) or genetic depletion of PKCδ. We also demonstrated that treatment with cocaine resulted in significant increases in nuclear factor erythroid-2-related factor 2 (Nrf-2) nuclear translocation and increased Nrf-2 DNA-binding activity in wild-type (WT) mice. These increases were more pronounced in the rottlerin-treated WT or PKCδ knockout mice than in the saline-treated WT mice. Although cocaine treatment increased Nrf-2 nuclear translocation, DNA binding activity, and γ-glutamyl cysteine ligases (i.e., GCLc and GCLm) mRNA expressions, while it reduced the glutathione level and GSH/GSSG ratio. These decreases were attenuated by PKCδ depletion. Cocaine treatment significantly increased alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in the serum of WT mice signifying the hepatic damage. These increases were also attenuated by PKCδ depletion. In addition, cocaine-induced hepatic degeneration in WT mice was evident 1 d post-cocaine. At that time, cocaine treatment decreased Bcl-2 and Bcl-xL levels, and increased Bax, cytosolic cytochrome c, and cleaved caspase-3 levels. Pharmacological or genetic depletion of PKCδ significantly ameliorated the pro-apoptotic properties and hepatic degeneration. Therefore, our results suggest that inhibition of PKCδ, as well as activation of Nrf-2, is important for protecting against hepatotoxicity induced by cocaine.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cocaine induces hepatotoxicity via oxidative stress and activation of PKCδ. </LI> <LI> Depletion of PKCδ protects from cocaine-induced hepatotoxicity. </LI> <LI> Depletion of PKCδ exerts antioxidant activity via Nrf2-related glutathione system. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>