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131.
Jin-Woong?Kim Jin-Gyu?Park Jee-Hyun?Ryu Ih-Seop?Chang Kyung-Do?SuhEmail author 《Colloid and polymer science》2005,283(11):1233-1240
This study presents a method to produce monodisperse chloromethyl-functionalized macroporous poly(styrene-co-divinylbenzene) polymer particles by seeded polymerization in aqueous media. We observed that the molecular structure of
polystyrene seed particles, the composition of the secondary monomer mixtures, and the type of solvents were very important
factors that determine the morphology and porosity of the final particles. This study proposes that the molecular chemistry
of polystyrene seed polymers, increasing molecular weight or crosslinking, is another factor that can control the porosity
of the final particles. Also, the selection of a poor solvent was effective in forming the larger surface area. In this study,
it was confirmed that the chloromethyl groups introduced on the surface of porous particles were quantified chemically and
their effective incorporation had a close relationship with the surface area. 相似文献
132.
Sung‐Nak Choi Sang‐Yub Kim Hae‐Wook Ryu Yong‐Min Lee 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(12):m504-m506
In the title compound, [HgCl2(C15H26N2)], the chiral alkaloid (6R,7S,8S,14S)‐(−)‐l ‐sparteine acts as a bidentate ligand, with two Cl− ligands occupying the remaining coordination sites, producing a distorted tetrahedron. The N—Hg—N plane is twisted by 81.1 (2)° from the Cl—Hg—Cl plane. The mid‐point of the N⋯N line does not lie exactly on the Cl—Hg—Cl plane but is tilted towards one of the N atoms by 0.346 Å. Similarly, the mid‐point of the Cl⋯Cl line is tilted toward one of the Cl atoms by 0.163 Å. The packing structure shows that the complex is stabilized by two interatomic Cl⋯H contacts involving both Cl atoms and the methylene or methine H atoms of the (−)‐sparteine ligand. 相似文献
133.
Sung-Sik You Hyeong-Won Ryu Young Cho Dae-Young Kim Thong-Sung Ko 《Reaction Kinetics and Catalysis Letters》1999,66(1):121-126
The nonenzymatic hydrolysis of RNA by polyvinylpyrrolidone (PVP) has been investigated. A bell-shaped kinetics was observed
when the first order rate constant of the reaction was ploted as a function of PVP concentration, which means the kinetic
feature of PVP as a degradative receptor distinct from those of degradative enzymes (e.g., ribonuclease). 相似文献
134.
The effects of annealing of B or N dual implanted regions in 15-20 Μm thick monocrystalline Β-SiC films has been investigated
using cross-sectional TEM, SIMS, Raman spectroscopy, C-V and sheet resistance measurements. Implantation resulted in buried
amorphous regions (in the B films) or highly disordered regions (in the N films) and residually strained regions. Annealing
for 300 s at selected temperatures between 1173 and 2073 K caused structural reordering, precipitation (in the B samples)
and dopant diffusion, as the temperature was progressively increased. Only slight changes were noted in the sheet resistance
of either type of sample as a result of annealing to 1973 K. However, the values of this parameter decreased markedly atT > 1973 K in both implanted and as-grown samples. Thus, this phenomenon was most probably caused by the formation of additionaln-type defects in the bulk of the materials.
Presented at the 1985 Electronic Materials Conference, Boulder, CO, June, 1985. 相似文献
135.
136.
Woonghwan Ryu Myung-Jin Yim Seungyoung Ahn Junho Lee Woopoung Kim Kyung-Wook Paik Joungho Kim 《Components and Packaging Technologies, IEEE Transactions on》2000,23(3):542-545
This paper firstly reports on the high-frequency SPICE model of the ACF flip-chip interconnections up to 13 GHz. The extraction process is based on an optimization procedure, called a genetic algorithm, which is known as a robust optimization tool. The proposed equivalent circuit model of the ACF interconnection can readily be used in SPICE circuit simulations for signal integrity analysis of high-frequency packages. Two different ACF interconnections were studied using the Au-coated polymer ball and Ni-filled ball. The extracted models of the two ACFs were found strongly dependent on not only size and rigidity of the conducting balls, but also on their magnetic permeability 相似文献
137.
Polarisation characteristics of the fused-taper-twisted single-mode-fibre coupler as a quarter-wave device are reported for the first time. In the case that circular polarisation is launched into the input port of the fused-fibre coupler, linear polarisation was observed at two output ports of the coupler, and an extinction ratio of about 30dB was obtained. 相似文献
138.
Herein, we report the fabrication of glycidyl methacrylate (GMA) polymeric conjugates of shortened multi‐walled carbon nanotubes (sMWCNT). The synthesis method involves the attachment of initiator on the surface of nanotubes followed by surface initiated atom transfer radical polymerization (SI‐ATRP) of GMA from the initiator‐bound sMWCNT surface. This is achieved by the procedure consisting of three important steps: introduction of amino groups onto the sMWCNT and attachment of polymerization initiator, 2‐bromo‐2‐methylpropinonyl bromide, and polymerization of GMA. The structure and properties of the resultant polymeric conjugates were characterized by Fourier transform infrared (FT‐IR) spectroscopy, Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X‐ray diffraction (XRD), atomic force microscopy (AFM), transmission electron microscopy (TEM) and SEM. The FT‐IR analysis of polymeric conjugates shows infrared (IR) peaks characteristic of GMA. AFM, TEM and SEM images clearly show the formation of poly(glycidyl methacrylate)(PGMA) polymer on sMWCNT surface. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
139.
140.
Nanocrystalline PbWO4 phosphor powders, which have scheelite structure, were successfully synthesized at low temperatures via a modified citrate complex route assisted by microwave irradiation. Crystallization of the PbWO4 precursor were detected at 400 °C, and entirely completed at 500 °C. Prepared PbWO4 nanocrystallites showed primarily spherical and disperse morphology. The average crystallite sizes were between 18 and 29 nm, showing an ordinary tendency to increase with temperature. The nanocrytalline PbWO4 phosphor powders exhibited spread-eagle shape of blue luminescence. Especially the PbWO4 phosphor powders prepared at 600 °C showed the strongest luminescent intensity, which was due to the higher crystallinity and homogeneous particle morphology. 相似文献