솔 - 젤 법으로 제조한 금속 담지 타이타니아 광촉매의 액상반응 특성

Anderson, Marc A,하흥용 한국화학공학회 1996 NICE Vol.14 No.4

솔 - 젤 법으로 제조한 금속 담지 타이타니아 광촉매의 액상반응 특성

하흥용,Anderson,Marc A 한국화학공학회 1996 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.34 No.3

스핀코팅법 및 침지코팅법을 이용하여 평판형 스테인레스 스틸 금속담체 위에 타이타니아 촉매를 담지시키고, 수용액상에서의 포름산 분해반응을 통해 광촉매 반응활성을 측정하였다. TiO₂/금속담체 촉매를 사용하는 경우에는 반응에 의해 금속담체 표면의 산화층이 환원되어 색깔이 변하는 현상이 관찰되었다. 담지된 타이타니아 촉매의 결정구조는 소결온도 600℃까지 아나타제 상을 유지하고 있었으며, 루타일 상은 관찰되지 않았다. 그러나 소결온도가 증가함에 따라 촉매의 반응활성이 급격히 감소되었다. 이것은 소결온도 증가시 촉매의 입자 크기가 증가하고 비표면적(BET 표면적)이 감소하기 때문에 나타나는 현상이다. 촉매를 금속판의 양면에 코팅하면 한 면에만 코팅한 경우에 비해 약 2배 정도의 반응활성을 보였다. 이것은 광촉매의 활성화 과정에서 생성된 전자들이 금속담체의 반대 면으로 이동되어 소비되므로써, election과 hole의 재결합반응이 억제되어 결과적으로 반응성이 증가된 때문이다. 촉매의 반응활성은 사용된 코팅방법에 큰 영향을 받지 않았다. TiO₂ catalysts supported on stainless steel plates were prepared by using either a spin-coating or a dip-coating method and tested for the photocatalytic degradation of formic acid in an aqueous solution. During the photodegradation reaction, the oxidized surface of the metallic support was reduced and bleached. The XRD patterns of the supported TiO₂ catalysts which were fired at temperatures up to 600℃ showed that all of the TiO₂ films had only an anatase structure, and the particle size increased as the firing temperature increased. The activity of the catalyst decreased with an increase in firing temperature, which implies a nearly linear relationship of the activity with the BET surface area of the TiO₂ catalyst. When the catalyst was coated on both side of the support plate, it appeared that total reaction rates increased as much as 2 times compared to those of the one-side-coated catalysts, even though UV light was illuminated only on one side of the catalyst plate in both cases. The activities of the catalysts were not affected by the coating methods employed.

Benzopyrimido-pyrrolo-oxazine-dione (<i>R</i>)-BPO-27 Inhibits CFTR Chloride Channel Gating by Competition with ATP

Kim, Yonjung,Anderson, Marc O.,Park, Jinhong,Lee, Min Goo,Namkung, Wan,Verkman, A. S. American Society for Pharmacology and Experimental 2015 Molecular pharmacology Vol.88 No.4

<P>We previously reported that benzopyrimido-pyrrolo-oxazinedione BPO-27 [6-(5-bromofuran-2-yl)-7,9-dimethyl-8,10-dioxo-11-phenyl-7,8,9,10-tetrahydro-6H-benzo[b]pyrimido [4',5': 3,4]pyrrolo [1,2-d][1,4]oxazine-2-carboxylic acid] inhibits the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel with low nanomolar potency and reduces cystogenesis in a model of polycystic kidney disease. We used computational chemistry and patch-clamp to show that enantiomerically pure (R)-BPO-27 inhibits CFTR by competition with ATP, whereas (S)-BPO-27 is inactive. Docking computations using a homology model of CFTR structure suggested that (R)-BPO-27 binds near the canonical ATP binding site, and these findings were supported by molecular dynamics simulations showing a lower binding energy for the (R) versus (S) stereoisomers. Three additional lower-potency BPO-27 analogs were modeled in a similar fashion, with the binding energies predicted in the correct order. Whole-cell patch-clamp studies showed linear CFTR currents with a voltage-independent (R)-BPO-27 block mechanism. Single-channel recordings in inside-out patches showed reduced CFTR channel open probability and increased channel closed time by (R)-BPO-27 without altered unitary channel conductance. At a concentration of (R)-BPO-27 that inhibited CFTR chloride current by similar to 50%, the EC50 for ATP activation of CFTR increased from 0.27 to 1.77 mM but was not changed by CFTRinh-172 [4-[[4-oxo-2-thioxo-3-[3-trifluoromethyl)phenyl]-5-thiazolidinylidene]methyl]benzoic acid], a thiazolidinone CFTR inhibitor that acts at a site distinct from the ATP binding site. Our results suggest that (R)-BPO-27 inhibition of CFTR involves competition with ATP.</P>

기체분리용 세라믹 복합분리막의 개발: I. 극미세 입자 실리카 졸의 코팅 특성

현상훈,윤성필,Marc A. Anderson 한국세라믹학회 1992 한국세라믹학회지 Vol.29 No.6

Alumina tubes suitable for the support of gas separation membranes have been prepared by the slipcasting technique. These supports have the average pore size of 0.1 ${\mu}{\textrm}{m}$ within the narrow distribution. The sol-gel dipcoating process of nanoparticulate sols is very sensitive to microstructure of the support, and the coating on the inside surface of the tube is found to be more successful than on the outside surface. Nanoparticulate silica sols (0.82 mol/ι) have been synthesized by an interfacial hydrolysis reaction between TEOS and high alkaline water. When coating an alumina tube with these sols, the minimum limits of the particle size and the aging time required for forming the coated gel layer at the given pH are provided. It is optimum to coat the support with less concentrated sols stabilized through aging for the appropriate time (more than 22 days) at the lower pH (pH 2.0) for producing a reproducible crack free thin film coating in composite membranes.

솔 - 젤 법으로 제조한 금속담지 타이타니아 광촉매의 액상반응 특성

하흥용 ( Heung Yong Ha ),Marc A . Anderson 한국화학공학회 1995 화학공학의이론과응용 Vol.1 No.1

Plasmon-Enhanced Photoelectrochemical Water Splitting with Size-Controllable Gold Nanodot Arrays

Kim, Hyung Ju,Lee, Sang Ho,Upadhye, Aniruddha A.,Ro, Insoo,Tejedor-Tejedor, M. Isabel,Anderson, Marc A.,Kim, Won Bae,Huber, George W. American Chemical Society 2014 ACS NANO Vol.8 No.10

<P>Size-controllable Au nanodot arrays (50, 63, and 83 nm dot size) with a narrow size distribution (±5%) were prepared by a direct contact printing method on an indium tin oxide (ITO) substrate. Titania was added to the Au nanodots using TiO<SUB>2</SUB> sols of 2–3 nm in size. This created a precisely controlled Au nanodot with 110 nm of TiO<SUB>2</SUB> overcoats. Using these precisely controlled nanodot arrays, the effects of Au nanodot size and TiO<SUB>2</SUB> overcoats were investigated for photoelectrochemical water splitting using a three-electrode system with a fiber-optic visible light source. From UV–vis measurement, the localized surface plasmon resonance (LSPR) peak energy (<I>E</I><SUB>LSPR</SUB>) increased and the LSPR line width (Γ) decreased with decreasing Au nanodot size. The generated plasmonic enhancement for the photoelectrochemical water splitting reaction increased with decreasing Au particle size. The measured plasmonic enhancement for light on/off experiments was 25 times for the 50 nm Au size and 10 times for the 83 nm Au nanodot size. The activity of each catalyst increased by a factor of 6 when TiO<SUB>2</SUB> was added to the Au nanodots for all the samples. The activity of the catalyst was proportional to the quality factor (defined as <I>Q</I> = <I>E</I><SUB>LSPR</SUB>/Γ) of the plasmonic metal nanostructure. The enhanced water splitting performance with the decreased Au nanodot size is probably due to more generated charge carriers (electron/hole pair) by local field enhancement as the quality factor increases.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2014/ancac3.2014.8.issue-10/nn504484u/production/images/medium/nn-2014-04484u_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn504484u'>ACS Electronic Supporting Info</A></P>

TSCOT ⁺ Thymic Epithelial Cell-Mediated Sensitive CD4 Tolerance by Direct Presentation

Ahn, Sejin,Lee, Gwanghee,Yang, Soo Jung,Lee, Deokjae,Lee, Seunghyuk,Shin, Hyo Sun,Kim, Min Cheol,Lee, Kee Nyung,Palmer, Douglas C,Theoret, Marc R,Jenkinson, Eric J,Anderson, Graham,Restifo, Nicholas P Public Library of Science 2008 PLoS biology Vol.6 No.8

<▼1><P>Although much effort has been directed at dissecting the mechanisms of central tolerance, the role of thymic stromal cells remains elusive. In order to further characterize this event, we developed a mouse model restricting LacZ to thymic stromal cotransporter (TSCOT)-expressing thymic stromal cells (TDLacZ). The thymus of this mouse contains approximately 4,300 TSCOT<SUP>+</SUP> cells, each expressing several thousand molecules of the LacZ antigen. TSCOT<SUP>+</SUP> cells express the cortical marker CDR1, CD40, CD80, CD54, and major histocompatibility complex class II (MHCII). When examining endogenous responses directed against LacZ, we observed significant tolerance. This was evidenced in a diverse T cell repertoire as measured by both a CD4 T cell proliferation assay and an antigen-specific antibody isotype analysis. This tolerance process was at least partially independent of <I>Autoimmune Regulatory Element</I> gene expression. When TDLacZ mice were crossed to a novel CD4 T cell receptor (TCR) transgenic reactive against LacZ (BgII), there was a complete deletion of double-positive thymocytes. Fetal thymic reaggregate culture of CD45- and UEA-depleted thymic stromal cells from TDLacZ and sorted TCR-bearing thymocytes excluded the possibility of cross presentation by thymic dendritic cells and medullary epithelial cells for the deletion. Overall, these results demonstrate that the introduction of a neoantigen into TSCOT-expressing cells can efficiently establish complete tolerance and suggest a possible application for the deletion of antigen-specific T cells by antigen introduction into TSCOT<SUP>+</SUP> cells.</P></▼1><▼2><P><B>Author Summary</B></P><P><B/></P><P>T cells play critical roles in the immune response. While developing in the thymus (from whence T cells and their precursors, thymocytes, derive their name), thymocytes are selected for the ability to recognize harmful antigen (positive selection), while those that respond to antigens present in their own body are eliminated (negative selection). Dogma holds that the thymus is divided into different functional compartments to ensure that these contrasting selection processes occur efficiently: the cortex is thought to be responsible for positive selection and the medulla for negative selection. In this study, we made use of a novel transgenic mouse (carrying a LacZ marker in a small fraction of cells in the cortex) to test whether the cortex is really excluded from negative selection. We were able to show that the introduced LacZ “antigen” present only in the cortical cells leads them to eliminate any LacZ-reactive T cells from the immune repertoire and leads to tolerance of the LacZ “antigen” by the body's immune system. This process is highly efficient, such that a relatively tiny number of antigen molecules present in a small fraction of the cells in the thymic cortex can singularly perform proofreading of all developing thymocytes.</P></▼2><▼3><P>A new study shows that antigen-specific negative selection of developing thymocytes is a property of thymic cortical epithelial cells, challenging the view that this process requires contact with specialized antigen-presenting cells found in the thymic medulla.</P></▼3>