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排序方式: 共有1678条查询结果,搜索用时 31 毫秒
31.
S. M. Jeong S.-B. Park S.-S. Hong C.-S. Seo S.-W. Park 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):349-356
Summary The
electrolytic reduction of U3O8 powder was carried out
using LiCl-Li2O molten salt in a 20-kg U3O8
batch cell to verify the feasibility of the process. As the current passes the
cell, the decomposition of Li2O and the reduction of U3O8
occur simultaneously in a cathode assembly and oxygen gas evolvs at the anode.
The results from a 20-kg U3O8 scale cell were compared
with data obtained from a bench scale cell. The results suggest a successful
demonstration of this process, exhibiting a reduction conversion of U3O8
of more than 99% in a batch.</p>
</p> 相似文献
32.
Seo M Nie Z Xu S Lewis PC Kumacheva E 《Langmuir : the ACS journal of surfaces and colloids》2005,21(11):4773-4775
We used coupling of flow and geometric confinement to assemble emulsion droplets in two-dimensional gliding lattices with a high degree of order and symmetry. Highly monodisperse discoid droplets with circular shapes were generated in a microfluidic flow-focusing device. Originally, close-packed lattices formed from these circular discoid droplets. Progressive confinement led to the gradual deformation of the circular disks: first, they elongated in the direction parallel to the direction of flow and then transformed into hexagons. Assembly driven by the combination of flow and confinement also allowed for the formation of lattices from droplets with a bimodal size distribution. We used photopolymerization of the monomer droplets to trap the lattice structure in the solid state and produce highly periodic arrays of solid polymer disks. 相似文献
33.
Ju-Woon Lee Ji-Hyun Seo Jae-Hun Kim Soo-Young Lee Joong-Won Park Myung-Woo Byun 《Radiation Physics and Chemistry》2007,76(11-12):1895-1898
House dust mites, Dermatophagoides farinae (DF) and Dermatophagoides pteronyssinus, are major allergens in the most common indoor allergen and are important risk factor for asthma. The modified antigen has been studied to treat allergic disorder. This study was carried out to measure possibility of modified allergen using gamma irradiation to treat allergy such as asthma. DF solutions (2 mg/ml) as target allergen were irradiated with Co-60 at 50 and 100 kGy. Conformational alternation of irradiated DF was observed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Levels of anti-irradiated DF mouse IgGs (sub-isotypes) against intact DF were measured similar to that of anti-intact DF IgGs. The binding abilities of house dust mite-allergic patients’ IgE were reduced depending on radiation dose, and irradiation could inhibit the binding ability of patients’ IgE more than 40%. This study has shown that the binding ability of IgE was reduced by conformational alteration by irradiation and the irradiated DF had epitopes capable to induce immunogeniciy. 相似文献
34.
Seo K Kim C Choi YS Park KA Lee YH Kim B 《Journal of the American Chemical Society》2003,125(46):13946-13947
CO2 molecule chemisorbs selectively on the zigzag tube edge without an activation barrier, whereas it physisorbs on the armchair edge of nanotubes. In addition, carbon nanotubes can be etched by an adsorbed oxygen atom of CO2 molecule. From our results, we suggest a selective etching mechanism for tuning the chirality of the mass-produced carbon nanotubes. 相似文献
35.
36.
Ki-Heon Kim Yong-Chil Seo Hoon Nam Hyun-Tae Joung Jae-Cheon You Dong-Jin Kim Yong-Chan Seo 《Microchemical Journal》2005,80(2):171-181
Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in slag of fly ash from three municipal solid waste (MSW) incinerators were analyzed to observe any changes in characteristics and distribution of their congeners by melting process. Actual concentration and Toxic Equivalent (TEQ) concentration profiles of 17 major congeners of PCDDs/PCDFs for gas, fly ash and melted slag were compared. The distributions of PCDDs/PCDFs in different streams macroscopically showed similarities with the generally known profiles for emission gas from a municipal waste incinerator. The total concentrations of PCDDs/PCDFs in off-gas and fly ash have been known to be a function of incineration conditions and of air pollution control device utilization; however, their normalized distributions were independent of such conditions. The concentrations of PCDDs/PCDFs in the melted slag of fly ash were not related to the concentrations of PCDDs/PCDFs congeners in fly ash but were rather a function of the melting furnace type and operation. The total amount of PCDDs/PCDFs in the melted slag of fly ash contained almost 150–27,000 times less dioxin than that in fly ash, however, the TEQ of dioxin in the slag was reduced by 435–43,500 times, which could enable them to be utilized as recycled construction materials. In normalized TEQ concentration profiles of 17 congeners of PCDDs/PCDFs, the ratio of PCDFs to PCDDs changed from 1.32 to 2.19 by melting, which showed relatively higher portion of furans left in melted slag than those in fly ash. By comparing reduction ratios of different congeners, PCDDs (dioxins) were relatively easier to destruct than PCDFs (furans) during melting process. The most difficult congener to destruct could be octa-chlorinated dibenzofuran (OCDF) among major congeners. For slag cooling methods, dioxin concentration in TEQ of slow cooled slag by air was four times higher than that of fast cooled slag by water. Thus cooling by water is more appropriate with the added beneficial effect of producing granules/particles, which can be utilized as roadbed materials. 相似文献
37.
We report a simple synthetic protocol for the 1,3-dipolar cycloaddition of azides with electron-deficient alkynes. Alkyne with at least one neighboring electron-withdrawing group proceeds with the cycloaddition successfully without any catalysts at room temperature in water. Under this simple condition, we evaluated a series of small molecule model reactions and then coupled an azido-DNA molecule with electron-deficient alkynes for the formation of [1,2,3]-triazole heterocycle, providing a potential method for introducing functional groups to DNA under biological conditions. 相似文献
38.
Kim SW Oh HM Kim BS Chung HT Han WC Kim EC Kim TH Seo GS Lyou JH Nah YH Jung JC Choi SC Jun CD 《Experimental & molecular medicine》2003,35(1):53-59
Tumor target-derived soluble secretary factor has been known to influence macrophage activation to induce nitric oxide (NO) production. Since heme oxygenase-1 (HO-1) is induced by a variety of conditions associated with oxidative stress, we questioned whether soluble factor from tumor cells induces HO-1 through NO-dependent mechanism in macrophages. We designated this factor as a tumor-derived macrophage-activating factor (TMAF), because of its ability to activate macrophages to induce iNOS. Although TMAF alone showed modest activity, TMAF in combination with IFN-gamma significantly induced iNOS expression and NO synthesis. Simultaneously, TMAF induced HO-1 and this induction was slightly augmented by IFN-gamma. Surprisingly, however, induction of HO-1 by TMAF was not inhibited by the treatment with the highly selective iNOS inhibitor, 1400 W, indicating that TMAF induces the HO-1 enzyme by a NO-independent mechanism. While rIFN-gamma alone induced iNOS, it had no effect on HO-1 induction by itself. Collectively, the current study reveals that soluble factor from tumor target cells induces HO-1 enzyme in macrophages. However, overall biological significance of this phenomenon remains to be determined. 相似文献
39.
New solid-gas metathetical synthesis of binary metal polysulfides and sulfides at intermediate temperatures: utilization of boron sulfides 总被引:1,自引:0,他引:1
A new simple synthetic method for binary metal polysulfides and sulfides was developed by utilizing an in situ formation of boron sulfides and their subsequent reactions with metal-source oxides in a closed container at intermediate temperatures above 350 degrees C at which the boron sulfides react in a gaseous form. The versatility of the new method is demonstrated with oxides of various transition metals (Ti, V, Mn, Fe, Ni, Nb, Mo, Ru, and W) and rare-earth metals (Y, Ce, Nd, Sm, Eu, Tb, and Er) as starting materials that exhibit different chemical characteristics. Regardless of the oxidation states of metals in the starting materials, the sulfidation reactions occurred quantitatively with stoichiometric mixtures of boron and sulfur, and within 24 h the reactions yielded pure products of TiS(2), TiS(3), VS(4), FeS(2), NiS(2), NbS(3), MoS(2), RuS(2), WS(2), Y(2)S(3), and RS(2) (R = Ce, Nd, Sm, Eu, Tb, and Er) which were the thermodynamically stable phases under the reaction conditions. The scope and implications of the new sulfidation method are also discussed. 相似文献
40.
Jin Y Yoon I Seo J Lee JE Moon ST Kim J Han SW Park KM Lindoy LF Lee SS 《Dalton transactions (Cambridge, England : 2003)》2005,(4):788-796
The NO2S2-donor macrocycle (L1) was synthesised from the ring closure reaction between Boc-N-protected 2,2'-iminobis(ethanethiol) (3) and 2,2'-(ethylenedioxy)bis(benzyl chloride) (4) followed by deprotection of the Boc-group. alpha,alpha'-Dibromo-p-xylene was employed as a dialkylating agent to bridge two L1 to yield the corresponding N-linked product (L2). The X-ray structure of L2 (as its HBr salt) is described. A range of Cd(II) and Hg(II) complexes of L1 (6-9) and L2 (10-12) were prepared and characterised. Reaction of HgX2 (X = Br or I) with L1 afforded [Hg(L1)Br]2[Hg2Br6].2CH2Cl2 6 and [Hg(L1)I(2)] 7, respectively. For 6, the Hg(II) ion in the complex cation has a distorted tetrahedral coordination environment composed of S2N donor atoms from L1 and a bromo ligand. In 7 the coordination geometry is highly distorted tetrahedral, with the macrocycle coordinating in an exodentate manner via one S and one N atom. The remaining two coordination sites are occupied by iodide ions. [Hg(L1)(ClO4)]ClO4 8 was isolated from the reaction of Hg(ClO4)2 and L1. The X-ray structure reveals that all macrocyclic ring donors bind to the central mercury ion in this case, with the latter exhibiting a highly distorted octahedral coordination geometry. The O2S2-donors from the macrocyclic ring define the equatorial plane while the axial positions are occupied by the ring nitrogen as well as by an oxygen from a monodentate perchlorato ion. Reaction of Cd(NO3)(2).4H2O with L1 afforded [Cd(L1)(NO3)2](.)0.5CH2Cl2 9 in which L1 acts as a tridentate ligand, binding exo-fashion via its S2N donors. The remaining coordination positions are filled by two bidentate nitrate ions such that, overall, the cadmium is seven-coordinate. Reactions of HgX2(X = Br or I) with L2 yielded the isostructural 2 : 1 (metal : ligand) complexes, [Hg2(L2)Br4] 10 and [Hg2(L2)I(4)] 11. Each mercury ion has a distorted tetrahedral environment made up of S and N donors from an exodentate L2 and two coordinated halides. Contrasting with this, the reaction of L2 with Cd(NO3)(2).4H2O yielded a 1-D coordination network, {[Cd2(L2)(NO3)4].2CH2Cl2}n 12 in which each ring of L2 is exo-coordinated via two S atoms and one N atom to a cadmium ion which is also bound to one monodentate and one bidentate nitrate anion. The latter also has one of its oxygen atom attached to a neighboring cadmium via a nitroso (mu2-O) bridge such that the overall coordination geometry about each cadmium is seven-coordinate. The [Cd(L2)0.5(NO3)2] units are linked by an inversion to yield the polymeric arrangement. 相似文献