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61.
A new class of organic nanoparticles (CN-MBE nanoparticles) with a mean diameter of ca. 30-40 nm, which exhibit a strongly enhanced fluorescence emission, were prepared by a simple reprecipitation method. CN-MBE (1-cyano-trans-1,2-bis-(4'-methylbiphenyl)ethylene) is very weakly fluorescent in solution, but the intensity is increased by almost 700 times in the nanoparticles. Enhanced emission in CN-MBE nanoparticles is attributed to the synergetic effect of intramolecular planarization and J-type aggregate formation (restricted excimer formation) in nanopaticles. On/off fluorescence switching for organic vapor was demonstrated with CN-MBE nanoparticles. 相似文献
62.
Yong‐Min Lee Yoon‐Bo Shim Seung Jae Lee Sung Kwon Kang Sung‐Nak Choi 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(12):o733-o734
The structure of the title compound, C15H27N2+·ClO4?, consists of a monoprotonated sparteinium cation and a perchlorate anion. The two tertiary N atoms of the cation, one perchlorate O atom and a H atom form a bifurcated hydrogen bond, the four hydrogen‐bonding atoms being nearly in the same plane. 相似文献
63.
Reaction of CpMoMn(CO)(8) with elemental selenium and Me(3)NO in the absence of light yielded the diselenido complex CpMoMn(CO)(5)(mu-Se(2)), 2. Compound 2 contains a bridging diselenido ligand lying perpendicular to the Mo-Mn bond, Mo-Mn = 2.8421(10) A. In the presence of room light, the reaction yielded the tetranuclear metal complex Cp(2)Mo(2)Mn(2)(CO)(7)(mu(3)-Se)(4), 3 (36% yield), and 2 (7% yield). Compound 2 reacted with ethylene to yield the ethanediselenato complex CpMoMn(CO)(5)(mu-SeCH(2)CH(2)Se), 4, by insertion of ethylene into the Se-Se bond. Compound 2 also reacted with (PPh(3))(2)Pt(PhC(2)Ph) and CpCo(CO)(2) to yield the complexes CpMoMnPt(PPh(3))(2)(CO)(5)(mu(3)-Se)(2), 5, and Cp(2)CoMoMn(CO)(5)(mu(3)-Se)(2), 6, respectively, by insertion of the metal groupings CpCo and Pt(PPh(3))(2) into the Se-Se bond of 2. The oxo compound Cp(2)CoMo(O)Mn(CO)(5)(mu(3)-Se)(2), 7, was obtained from 6 by decarbonylation at molybdenum by using Me(3)NO. The molecular structures of the complexes 2-7 were established by single-crystal X-ray diffraction analyses. 相似文献
64.
The reactions of α-trifluoromethylated α-arylacetates 1 with 3 equiv of hydrazine, methylhydrazine or benzylhydrazine in 1,4-dioxane at reflux for 24 h afforded the corresponding 5-fluoropyrazolin-3-one derivatives 3a-m in high yields. Similarly, treatment of 1 with 3 equiv of PhNLiNH2 in THF at −78 °C, followed by warming to room temperature, resulted in the formation of 3n-s in high yields. 相似文献
65.
Kim WS Park M Lee DW Moon MH Lim H Lee S 《Analytical and bioanalytical chemistry》2004,378(3):746-752
Fly ash has been regarded as hazardous because of its high adsorption of toxic organic and/or inorganic pollutants. Fly ash is also known to have broad distributions of different chemical and physical properties, such as size and density. In this study, fly ash emitted from a solid waste incinerator was pre-fractionated into six sub-populations by use of gravitational SPLITT fractionation (GSF). The GSF fractions were then analyzed by sedimentation field-flow fractionation (SdFFF) and ICP–AES. SdFFF analysis showed the fly ash has a broad size distribution ranging from a few nanometers up to about 50 µm. SdFFF results were confirmed by electron microscopy. Inductively coupled plasma–atomic emission spectroscopy (ICP–AES) analysis of the GSF fractions showed the fly-ash particles contain a variety of inorganic elements including Ca, Si, Mg, Fe, and Pb. The most abundant in fly ash was Ca, followed by Si then Mg. No correlations were found between trace element concentration and particle size. 相似文献
66.
The mass spectral decomposition modes of a series of 2-imino-4-thiazolidinone derivatives are reported and discussed. The fragmentation patterns and mechanisms postulated have been confirmed by the analysis of the MIKE spectra and using DADI technique and the effects of heteroatoms and substituents on the MIKE spectrum of these compounds are compared with that of 3-substituted hydantoins. 相似文献
67.
A. Subbiah Pandi V. Rajakannan D. Velmurugan Masood Parvez Moon‐Jib Kim A. Senthilvelan S. Narasinga Rao 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(3):o164-o167
N‐(2‐Chlorobenzyl)‐1,2,3,4‐tetrahydroisoquinoline‐1,3‐dione, C16H12ClNO2, crystallizes in P21/n with three crystallographically independent molecules in the asymmetric unit, which differ slightly in conformation, N‐(2‐bromo‐4‐methylphenyl)‐1,2,3,4‐tetrahydroisoquinoline‐1,3‐dione, C16H12BrNO2, crystallizes in P21/n with one molecule in the asymmetric unit andN‐(2,3‐dichlorophenyl)‐1,2,3,4‐tetrahydroisoquinoline‐1,3‐dione, C15H9Cl2NO2, crystallizes in P21/c with one molecule in the asymmetric unit. In all three structures, the heterocyclic rings adopt approximately planar conformations. The pyridine rings are orthogonal to the substituted phenyl rings. In all three structures, the crystal packing is stabilized by intermolecular C—H?O hydrogen bonds. 相似文献
68.
The separation of wide molecular mass (Mr) ranges of macromolecules using frit inlet asymmetrical flow field-flow fractionation (FI-AFlFFF) has been improved by implementing a combination of field and flow programming. In this first implementation, field strength (governed by the cross flow-rate through the membrane-covered accumulation wall) is decreased with time to obtain faster elution and improved detection of the more strongly retained (high Mr) materials. The channel outlet flow-rate is optionally held constant, increased, or decreased with time. With circulation of the flow exiting the accumulation wall to the inlet frit, the dual programming of cross flow and channel outlet flow could be implemented using just two pumps. With this flow configuration, the channel outlet flow-rate is always equal to the channel inlet flow-rate, and these may be programmed independently of the cross flow-rate through the membrane. FI-AFlFFF retains its operational advantage over conventional asymmetrical flow FFF (AFlFFF). Unlike conventional AFlFFF, FI-AFlFFF does not require time consuming, and experimentally inconvenient, sample focusing and relaxation steps involving valve switching and interruption of sample migration. The advantages of employing dual programming with FI-AFlFFF are demonstrated for sets of polystyrene sulfonate standards in the molecular mass range of 4 to 1000 kDa. It is shown that programmed FI-AFlFFF successfully expands the dynamic separation range of molecular mass. 相似文献
69.
Glypican-3 (GPC3) encodes a cell-surface heparan- sulfate proteoglycan and its expression is frequently silenced in ovarian cancer, mesotheliomas, and breast cancer cell lines and ectopic expression of GPC3 inhibited the growth of these cells, suggesting that GPC3 plays a negative role in cell proliferation. In contrast, up-regulation of GPC3 is often observed in hepatoma, neuroblastoma, and Wilms' tumor. Whether GPC3 plays the same growth inhibitory role in these tumors remains to be studied. Here we report that antisense-mediated knockdown of GPC3 in the HepG2 hepatoma cells significantly promotes the growth of hepatoma cells. In addition, we show that this growth promotion is independent of insulin-like growth factor 2 (IGF2) signaling. Our data suggest that GPC3 plays a growth-suppressing role in hepatoma and provide cell biological evidence inconsistent with the hypothesis that GPC3 acts as a growth suppressor by downregulating IGF2. 相似文献
70.
The excited-state proton-transfer dynamics of 7-azaindole occurring in the water nanopools of reverse micelles has been investigated by measuring time-resolved fluorescence spectra and kinetics, as well as static absorption and emission spectra, with varying water content and isotope. 7-Azaindole molecules are found to exist in the bound-water regions of reverse micelles. The rate constant and the kinetic isotope effect of proton transfer are smaller than those in bulk water although both increase with the size of the water nanopool. The retardation of proton transfer in the bound regions is attributed to the increased free energy of prerequisite solvation to form a cyclically H-bonded 1:1 7-azaindole/water complex. 相似文献