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171.
Soo‐Gyun Roh Jong Hwa Jeong 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):e120-e121
In the title compound, [{η5‐CpCo[P(O)(OMe)2]3}Nd(O2CCH3)2]2, with a centrosymmetric molecule, each Nd atom has an eight‐coordination environment, surrounded by a tripodal {LOMe = CpCo[P(O)(OMe)2]3} and four bridging acetato ligands. The coordination geometry around each Nd centre is described as a distorted square‐antiprism and the two different types of acetato ligands have μ‐O:O′‐ and μ‐O,O′:O′‐acetato coordination modes. The Nd—O distances are in the range 2.378 (4)–2.594 (5) Å and the Nd?Nd distance is 3.9913 (6) Å. 相似文献
172.
Correlations between acoustic properties and bone density were investigated in the 12 defatted bovine cancellous bone specimens in vitro. Speed of sound (SOS) and broadband ultrasonic attenuation (BUA) were measured in three different frequency bandwidths from 0.5 to 2 MHz using three matched pairs of transducers with the center frequencies of 1, 2.25, and 3.5 MHz. The relative orientation between ultrasonic beam and bone specimen was the mediolateral (ML) direction of the bovine tibia. SOS shows significant linear positive correlation with apparent density for all three pairs of transducers. However, BUA shows relatively weak correlation with apparent density. SOS and BUA are only weakly correlated with each other. The linear combination of SOS and BUA in a multiple regression model leads to a significant improvement in predicting apparent density. The correlations among SOS, BUA, and bone density can be effectively and clearly represented in the three-dimensional space by the multiple regression model. These results suggest that the frequency range up to 1.5 MHz and the multiple regression model in the three-dimensional space can be useful in the osteoporosis diagnosis. 相似文献
173.
H.S. Roh Y.C. Kang H.D. Park S.B. Park 《Applied Physics A: Materials Science & Processing》2003,76(2):241-245
Y2O3:Eu phosphor particles were prepared by large-scale spray pyrolysis. The morphological control of Y2O3:Eu particles in spray pyrolysis was attempted by adding polymeric precursors to the spray solution. The effect of composition
and amount of polymeric precursors on the morphology, crystallinity and photoluminescence characteristics of Y2O3:Eu particles was investigated. Particles prepared from a solution containing polyethylene glycol (PEG) with an average molecular
weight of 200 had a hollow structure, while those prepared from solutions containing adequate amounts of citric acid (CA)
and PEG had a spherical shape, filled morphology and clean surfaces after post-treatment at high temperature. Y2O3:Eu particles prepared from an aqueous solution with no polymeric precursors had a hollow structure and rough surfaces after
post-treatment. The phosphor particles prepared from solutions with inadequate amounts of CA and/or PEG also had hollow and/or
fragmented structures. The particles prepared from the solution containing 0.3 M CA and 0.3 M PEG had the highest photoluminescence
emission intensity, which was 56% higher than that of the particles prepared from aqueous solution without polymeric precursors.
Received: 22 March 2002 / Accepted: 26 March 2002 / Published online: 5 July 2002
RID="*"
ID="*"Corresponding author. Fax: +82-42/861-4245, E-mail: yckang@pado.krict.re.kr 相似文献
174.
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176.
Roh HS Choi GK An JS Cho CM Kim DH Park IJ Noh TH Kim DW Hong KS 《Dalton transactions (Cambridge, England : 2003)》2011,40(26):6901-6905
We demonstrated the formation of monodispersed spherical aluminum hydrous oxide precursors with tunable sizes by controlling the variables of a forced hydrolysis method. The particle sizes of aluminum hydrous oxide precursors were strongly dependent on the molar ratio of the Al(3+) reactants (sulfates and nitrates). In addition, the systematic phase and morphological evolutions from aluminum hydrous oxide to γ-alumina (Al(2)O(3)) and finally to α-Al(2)O(3) through thermal dehydrogenation were characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). After annealing the amorphous aluminum hydrous oxide in air at 900 °C and 1100 °C for 1 h, we observed complete conversion to phase-pure γ- and α-Al(2)O(3), respectively, while maintaining monodispersity (125 nm, 195 nm, 320 nm, and 430 nm diameters were observed). Furthermore, both γ- and α-Al(2)O(3) were found to be mesoporous in structure, providing enhanced specific surface areas of 102 and 76 m(2) g(-1), respectively, based on the Brunauer-Emmett-Teller (BET) measurement. 相似文献
177.
While DNA is a genetic material, it is also an inherently polymeric material made from repeating units called nucleotides. Although DNA's biological functions have been studied for decades, the polymeric features of DNA have not been extensively exploited until recently. In this tutorial review, we focus on two aspects of using DNA as a polymeric material: (1) the engineering methods, and (2) the potential real-world applications. More specifically, various strategies for constructing DNA-based building blocks and materials are introduced based on DNA topologies, which include linear, branched/dendritic, and networked. Different applications in nanotechnology, medicine, and biotechnology are further reviewed. 相似文献
178.
In this study, we elucidated a small molecule inhibitor on viral protein NS5B identified through a high-throughput screening strategy using optical nanoparticle-based RNA oligonucleotide. We have previously shown that quantum dots (QDs)-RNA oligonucleotide can specifically recognize the HCV viral proteins. We have also demonstrated that conjugated QDs-RNA oligonucleotide can specifically and sensitively interact with designed biochips [1] and [2]. Among the flavonoids examined, (−)-epigallocatechin gallate (EGCG) demonstrated a remarkable inhibition activity on HCV viral protein, NS5B. (−)-Epigallocatechin gallate, at 0.005 μg mL−1 or more, concentration-dependently attenuated the binding affinity on a designed biochip as evidenced by QDs-RNA oligonucleotide. At a concentration of 0.1 μg mL−1, (−)-epigallocatechin gallate showed a 50% inhibition activity on QDs-RNA oligonucleotide biochip assay. We screened a small molecule inhibitor on the viral protein, NS5B, identified through a high-throughput screening strategy using on-chip optical nanoparticle-based RNA oligonucleotide on chip. In this designed strategy, the convenient and efficient screening and development of an on-chip viral protein inhibitor using a QDs-RNA oligonucleotide assay is achievable with high sensitivity and simplicity. In addition, this platform is expected to be applicable toward the inhibitor screening of other types of diseases. 相似文献
179.
Structural Control of Hierarchically‐Ordered TiO2 Films by Water for Dye‐Sensitized Solar Cells
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Sung Hoon Ahn Dong Jun Kim Dr. Dong Kyu Roh Won Seok Chi Prof. Jong Hak Kim 《Chemphyschem》2014,15(9):1841-1848
A facile way of controlling the structure of TiO2 by changing the amount of water to improve the efficiency of dye‐sensitized solar cells (DSSCs) is reported. Hierarchically ordered TiO2 films with high porosity and good interconnectivity are synthesized in a well‐defined morphological confinement arising from a one‐step self‐assembly of preformed TiO2 (pre‐TiO2) nanocrystals and a graft copolymer, namely poly(vinyl chloride)‐g‐poly(oxyethylene methacrylate). The polymer–solvent interactions in solution, which are tuned by the amount of water, are shown to be a decisive factor in determining TiO2 morphology and device performance. Systematic control of wall and pore size is achieved and enables the bifunctionality of excellent light scattering properties and easy electron transport through the film. These properties are characterized by reflectance spectroscopy, incident photon‐to‐electron conversion efficiency, and electrochemical impedance spectroscopy analyses. The TiO2 photoanode that is prepared with a higher water ratio, [pre‐TiO2]:[H2O]=1:0.3, shows a larger surface area, greater light scattering, and better electron transport, which result in a high efficiency (7.7 %) DSSC with a solid polymerized ionic liquid. This efficiency is much greater than that of commercially available TiO2 paste (4.0 %). 相似文献
180.
I. J. Roh S. Y. Park J. J. Kim C. K. Kim 《Journal of Polymer Science.Polymer Physics》1998,36(11):1821-1830
Thin-film composite reverse osmosis membranes of polyamides were prepared by interfacial polymerization. Various benzenediamines and poly(aminostyrene) were interfacially reacted with various acyl chlorides to prepare a skin layer of composite membranes. Among the membranes prepared from the structural isomeric monomers of benzenediamines and acyl chlorides, i.e., the same chemical composition but different in the position of functional groups on the aromatic ring, the membrane with the best salt rejection was obtained when the reacting groups forming amide are located at the same position on the aromatic ring. Membranes prepared by interfacially reacting various diamines with trimesoyl chloride revealed that the salt rejection depends on the linear chain structure of polyamides and network formed by crosslinking. Membranes obtained by interfacial polymerization of poly(aminostyrene) with trimesoyl chloride showed higher water flux but lower salt rejection than those obtained by interfacial polymerization of various benzenediamines with trimesoyl chloride. Membranes obtained here showed the typical trade-off behavior between salt rejection and water flux. However, membranes prepared by interfacially reacting trimesoyl chloride with a mixture of poly(aminostyrene) and m-phenylenediamine or a mixture of poly(aminostyrene), m-phenylenediamine, and diaminobenzoic acid showed a performance advantage over usual membranes, i.e., a large positive deviation from the usual trade-off trend. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36 : 1821–1830, 1998 相似文献