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Purification, crystallization, and X-ray crystallographic analysis of Nit2 from Kluyveromyces lactis
Chaewon Jin,Hyeonseok Jin,Bradley Quade,Jeong Ho Chang 한국구조생물학회 2020 Biodesign Vol.8 No.1
The nitrilase-like (NIT) protein subfamily is a member of the nitrilase superfamily, which exhibits CN hydrolase activity. NIT proteins are highly conserved, and mammals have Nit1 and Nit2. Nit proteins are putative tumor suppressors; however, the enzymatic activities of Nit1 and Nit2 are different. Nit1 is a metabolite repair enzyme, whereas Nit2 is an ω-amidase. In this study, in order to understand the structural features and functional diversity of Nit proteins, Nit2 from Kluyveromyces lactis was crystallized, and X-ray diffraction data were obtained at a resolution of 2.2 Å. The crystal of K. lactis Nit2 (KlNit2) belonged to the space group C2, with the unit cell parameters a = 79.0 Å, b = 211.1 Å, c = 89.4 Å, α = γ = 90°, β = 112.1°. The crystal contained four macromolecules in the asymmetric unit.
Jo, Yong Jin,Kim, Chaewon,Lee, Jun Hyeok,Ko, μ Seok,Jo, Anjae,Kim, Jin-Yeol,Jung, Woo-Gwang,Lee, Nohyun,Kim, Youn Hee,Kim, Jiyoung American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.11
<P>Transparent conductive films (TCFs) are indispensable components for various optoelectronic devices. Recently, the development of flexible TCFs has received attention for applications in flexible and wearable electronics. In this work, we developed silver nanowires (Ag NWs) with a mesh pattern to obtain the optical and electrical properties, as well as flexibility, required for touch screen panels (TSPs). The Ag NW grid pattern was achieved using photolithography by employing a titanium adhesion layer between Ag NWs and substrates to attain a uniform and stable pattern. The transmittance and sheet resistance of patterned Ag NWs were 95% and 88 Omega/square, respectively, and the NWs showed good stability against bending operations for up to 2,000 bending cycles. Moreover, this fabrication process has the advantage of low cost and can be applied to a large-scale devices using a solution process.</P>
Kim, Chaewon,Park, Jin-Woo,Kim, Jiyoung,Hong, Sung-Jei,Lee, Mi Jung ELSEVIER SCIENCE 2017 Journal of Alloys and Compounds Vol.726 No.-
<P><B>Abstract</B></P> <P>A highly efficient transparent heater was intensively studied by optimizing a solution-processed indium tin oxide nanoparticles (ITO-NPs) film with oxygen vacancy control. To control the oxygen vacancy, ITO-NPs layers coated onto glass substrates was annealed under various atmospheric conditions such as vacuum, air, and argon (Ar). In result, all the solution-processed ITO films achieved high transparency of more than 96% in the visible range (500–730 nm) with respect to the glass substrate. As well, sheet resistance (R<SUB>s</SUB>) decreased with increasing temperature and the lowest R<SUB>s</SUB> (309.4 Ω/□) was achieved by annealing at 600 °C under Ar atmosphere. X-ray photoelectron spectroscopy (XPS) analysis revealed that the highest concentration of oxygen vacancies occurred under Ar atmosphere resulting in the highest carrier mobility and lowest R<SUB>s</SUB>. Furthermore, application of the ITO-NPs films to transparent heater was attempted. In result, when applying 15 V, ITO-NPs film annealed under Ar atmosphere, showing the lowest R<SUB>s</SUB>, exhibited the highest temperature (215.1 °C) among the samples. Also, highly thermal efficiency of 162.9 °C/(W/cm<SUP>2</SUP>) were achieved from the optimized sample. Thus, we suggest that the optimized ITO-NPs film was applicable to highly efficient transparent heater.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Highly efficient transparent heater was made with solution-processed ITO-NPs film. </LI> <LI> Oxygen vacancy of ITO film was optimized with heat-treatment under Ar atmosphere. </LI> <LI> The lowest R<SUB>s</SUB>(309.4 Ω/□) and highest T<SUB>550</SUB>(96%) were achieved with Ar atmosphere. </LI> <LI> High heat-generating temperature (215.1 °C) was achieved with Ar atmosphere. </LI> <LI> Highly thermal efficiency (162.9 °C/(W/cm<SUP>2</SUP>)) was achieved with Ar atmosphere. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Kim, Chaewon,Park, Jin-Woo,Lee, Yeo-Ryang,Lee, Mi Jung Elsevier 2017 Sensors and actuators. A Physical Vol.263 No.-
<P><B>Abstract</B></P> <P>Thin film transistors (TFTs) based on metal oxides have high mobility, transparency, and excellent stability, and are considered to be a key part of the next generation transparent electronic devices. Solution-processed metal oxide thin films using the sol-gel method has enabled the deposition of metal oxide thin films without a vacuum system, and it allows metal oxide TFTs to be fabricated more efficiently at low cost and over a large area through a simple process. In this study, we fabricated In<SUB>2</SUB>O<SUB>3</SUB> using the sol-gel method and adopted various self-assembled monolayers (SAMs) to modify the interface between the semiconductor and dielectric layer. We used octadecyltrichlorosilane as a hydrophobic surface and partially removed it through exposure to UV radiation to form a patterned semiconductor using a simple spin-coating procedure that remarkably reduced the leakage current. 3-aminopropylsilane, (3-mercaptopropyl)trimethoxysilane, and cyclopentadienyltrimethylsilane as SAM materials and toluene and water as solvents to dilute them were used to modify the surface of the SiO<SUB>2</SUB>. We measured the contact angle under various conditions and the electrical characteristics of the TFTs annealed in various temperatures of 230, 250, and 300°C to confirm the effect of interface energy modification, and concluded that surface energy affected the mobility of the In<SUB>2</SUB>O<SUB>3</SUB> transistors and the lower surface energy enhanced the mobility of the TFTs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The active layer was patterned using interface energy modification with octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) and UV exposure. </LI> <LI> The patterned active layer led to reduced parasitic resistance resulting in a leakage current during transistor operation. </LI> <LI> Modified interface energy at the channel area affected the electrical characteristics of the thin film transistors. </LI> <LI> We confirmed that high interface energy leads better wetting of metal oxide precursor solution to improve performances. </LI> </UL> </P>
Kim Hyo Jin,Kim Chaewon,Kim Seong Min,Kim Wang Gi 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.10
We have studied the dependence of the growth of GaAs on Si substrate on the flow rate of the source for GaAs seed layer. GaAs buffer with different growth conditions of the inserted GaAs seed has been grown on Si (001) substrate by using metalorganic chemical vapor deposition (MOCVD). Structural properties of the GaAs buffer were investigated by using scanning electron microscopy (SEM) and high-resolution X-ray diffraction (HRXRD). The number of misfit dislocation in the GaAs seeds on Si substrates decreased as the growth rate and the V/III ratio of the GaAs seed were increased and decreased, respectively. Also, we have investigated the improvement in GaAs buffer due to electron beam (e-beam) treatment. The peak position for the GaAs buffer on Si reached the original peak of the GaAs substrate due to the e-beam treatment. Finally, the efficiency of an AlGaAs/GaAs double junction solar cell on a Si substrate was about 22.6%.