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Mussel-inspired functionalization of carbon nanotubes for hydroxyapatite mineralization
Lee, Minah,Ku, Sook Hee,Ryu, Jungki,Park, Chan Beum Royal Society of Chemistry 2010 Journal of materials chemistry Vol.20 No.40
<P>Hydroxyapatite (HAp)/carbon nanotubes (CNTs) hybrid composite materials are successfully synthesized <I>via</I> a biomineralization process that employs poly(dopamine) (PDA), a synthetic mimic of mussel adhesive proteins. Creating bio-inorganic composites for regenerative medicine requires appropriate fillers to enhance their mechanical robustness; for example, natural bones are composed mainly of HAp supported by collagen fibers. In this regard, many efforts have been made to harness HAp as a bone substitute through its integration with reinforcing fibrous materials such as CNTs. We found that the formation of a PDA ad-layer on the surface of CNTs changed the hydrophobic CNTs to become bioactive. This enabled efficient interaction between the CNTs and mineral ions (<I>e.g.</I>, Ca<SUP>2+</SUP>), which facilitated the mineralization of HAp. CNTs functionalized with PDA (CNT-PDA) highly accelerated the formation of HAp when incubated in a simulated body fluid and exhibited a minimal cytotoxic effect on bone osteoblast cells compared to pristine or carboxylated CNTs. Our results show the potential of CNT-PDA as a scaffold material for bone tissue regeneration and implantation.</P> <P>Graphic Abstract</P><P>Carbon nanotubes (CNTs) functionalized with poly(dopamine) promoted biomimetic mineralization of hydroxyapatite and reduced the cytotoxic effect of CNTs on osteoblast cells making CNTs suitable for application in bone-related therapies. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0jm01339k'> </P>
Accelerated Life Test of Eco-Friendly PP-TPE Insulating Material Using Frequency Acceleration
Lee Sanggoon,Yoon Sungho,Kim Donguk,Kim Minah,Park Kyu-Hwan,Lee Seungjun,Kim Dongseob,Kim Jeongtae 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.5
An accelerated life test was performed under 600 Hz power frequency at 90 °C with an electrode specially designed for a flat specimen to derive the long-term reliability and lifetime index required for power cable development using PP-TPE (Polypropylene-Thermo Plastic Elastomer) insulation materials. It was difficult to ensure failure data for life because failure did not occur well in the accelerated life-test to which the constant-stress test was applied at a low electric field, so it was converted to the step-Stress test and performed. As a result, the lifetime index of PP-TPE was determined to be around 12 to 13 which was comparably lower than that of XLPE (Cross-Linked Polyethylene) having the index of 15. However, the number of failures shows that PP-TPE is smaller than XLPE and is rather more voltage endurance than XLPE, and it is judged that it is difficult to evaluate the characteristics simply with the lifetime index. The cause of initial failure was interpreted as the presence of large TPE lumps in the specimen or low dispersion of TPE. In the future, it is judged that a clearer lifetime index should be derived through long-term ageing experiments on model cables with a thickness of several mm.
Lee, Sang-Hun,Lee, Donggeun,Choi, Man Ho,Son, Joo-Hiuk,Seo, Minah American Chemical Society 2019 ANALYTICAL CHEMISTRY - Vol.91 No.10
<P>Discrimination and quantification of trace amounts of steroid hormones in biological specimens are needed to elucidate their changing expression because their biological functions are responsible for the development and prevention of endocrine disorders. Although mass-spectrometry-based assays are most commonly recommended, development of a new type of highly sensitive and selective detection methods in clinical practices is needed. Here, we introduce a label-free type of terahertz molecule sensor capable of sensing and identifying progesterone and 17α-OH-progesterone selectively. Nanoslot-array-based sensing chips were used as launching pads for absorption cross-section enhancement of molecules at a reliable terahertz frequency. With use of nanoslots with resonances at 1.17 THz corresponding to intrinsic THz absorption resonance mode for progesterone and at 1.51 THz for 17α-OH-progesterone, respectively, each steroid shows prominent transmittance change in terms of its amount. In particular, the sensing performance has been much improved by controlling evaporation speed, in turn resulting in an efficient, homogeneous distribution of the molecules onto a sensing hot spot.</P> [FIG OMISSION]</BR>
Settling and Filtering Processes for Treatment of Fine Suspended Solidsand Soluble Heavy Metals
Minah Oh(오민아),Wonki Kim(김원기),Seungjin Oh(오승진),Dukmin Kim(김덕민),SangHoon Lee(이상훈),Jai-Young Lee(이재영) 한국지반신소재학회 2013 한국토목섬유학회 학술발표회 Vol.2013 No.11
Fine suspended solids and heavy metals generated effluence from mine drainage could destroy environment as the aesthetic landscapes, and depreciate water quality. Therefore, the purpose of this research is focused on process development applied the actual field for controlling fine suspended solids and heavy metals, and so lab-scale test was performed for inducement of basic data. The mine drainage used in this research was sampled in H. mine located Jeongseon-gun, Gangwon-do. Concentration of suspended soil, arsenic, iron and manganese was exceeded the standard of contaminant limitation for the clean water, and particle size of suspended solid was less than 10 μm as fine particle. Although hydraulic retention time of mine drainage for effective settling was required more than 6 hours, hydraulic retention time would be increased in winter season when the settling efficiency could be reduced because of viscosity decreasing. Moreover, installed inclination plate helped to increase settling efficiency of suspended solid about 30 %. Filtering media that was the most effective removal of suspended solids and heavy metal was indicated granular activated carbon of 1~2 mm was the optimal size.