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991.
Gan Q Song G Xu Y Gao J Cao Q Pan X Zhong Y Yang G Zhu X Chen L 《Optics letters》2005,30(12):1470-1472
The fabrication of very-small-aperture lasers is demonstrated, and their performance is analyzed. Because of strong optical feedback caused by a gold film on the front facet of the laser, its behavior changes: The threshold current decreases, the density of light inside the laser diode and the redshift effect of the spectra are enhanced, and the laser diode's lifetime is shorter than that of common laser diodes with large driving current. 相似文献
992.
A time-of-flight imaging technique is introduced to visualize fluid flow and dispersion through porous media using NMR. As the fluid flows through a sample, the nuclear spin magnetization is modulated by rf pulses and magnetic field gradients to encode the spatial coordinates of the fluid. When the fluid leaves the sample, its magnetization is recorded by a second rf coil. This scheme not only facilitates a time-dependent imaging of fluid flow, it also allows a separate optimization of encoding and detection subsystems to enhance overall sensitivity. The technique is demonstrated by imaging gas flow through a porous rock. 相似文献
993.
Song Y Challa SR Medforth CJ Qiu Y Watt RK Pena D Miller JE van Swol F Shelnutt JA 《Chemical communications (Cambridge, England)》2004,(9):1044-1045
Nanotubes prepared by the self-assembly of D-Phe-D-Phe molecules are investigated by electron microscopy and Monte Carlo simulations; the nanotubes appear to be porous and are capable of forming novel peptide-nanotube platinum-nanoparticle composites. 相似文献
994.
995.
996.
A nano-liquid chromatographic /tandem mass spectrometric (nanoHPLC/MS/MS) method has been developed for the sensitive determination of histamine, a vital neurotransmitter. The method involved pre-column derivatization of histamine with 7-fluoro-4-nitrobenzoxadiazole (NBD-F), thus increasing the hydrophobicity of the analyte and allowing it to be retained and stacked on a nanoelectrospay emitter packed with C18 reversed-phase particles. Sodium 1-heptanesulfonate, added as an ion-pairing reagent in the mobile phase for sample loading, was found to facilitate greatly the analyte retention. The packed nanoelectrospray emitter was easily prepared using fused-silica capillary of 75 microm i.d., and included creating an electrospray emitter tip and then slurry-packing a 5 cm long column with 5 microm silica-based particles. After sample loading, the mobile phase was changed for separation and a characteristic precursor-to-product ion transition, m/z 275 --> 258, was used for the quantification. A linear calibration curve in the range from 1.0-100 ng/mL histamine with an r2 value of 0.9995 was obtained. The detection limit was estimated to be 0.1 ng/mL histamine in water. In a preliminary validation, the method was applied to determine histamine in alcoholic beverages and rat brain tissues. 相似文献
997.
Five novel lanthanide (Eu3+, Tb3+, Gd3+, Sm3+ and Dy3+) complexes with 2, 2'-bipyridine-N, N'-dioxide (bipyO2) were synthesized and characterized by elemental analysis, IR spectrum. The triplet state energy of bipy O2 was determined to be 22275 cm(-1) with the phosphorescence spectrum of bipy O2 and its gadolinium complex. The photophysical properties of these complexes indicated that the triplet state energy of the ligand is suitable for the sensitization of the luminescence of Eu3+, Tb3+, Sm3+ and Dy3+, especially of Tb3+. 相似文献
998.
X.H.?LiuEmail author M.H.?Hong W.D.?Song G.X.?Chen J.F.?Chong J.P.?Wang Y.H.?Wu T.C.?Chong 《Applied Physics A: Materials Science & Processing》2004,78(3):423-425
Barium ferrite (BaFe12O19) thin films have been deposited by pulsed laser deposition at 900 °C in 250 mTorr oxygen on Si substrates with Pt(111) underlayers. The barium ferrite films contained platelet grains and a small amount of acicular grains, with sizes of 300 nm and 80×300 nm, respectively, and had a surface roughness of 11 nm. Vibrating-sample magnetometer measurements indicated that the BaFe12O19 films have some perpendicular orientation, with a perpendicular squareness of 0.64 and an in-plane squareness of 0.28. The saturation magnetization is about 190 emu/cc. The perpendicular and in-plane coercivities are 2.1 kOe and 1.6 kOe, respectively. PACS 75.50.Ss; 75.60.Ej; 75.70.Ak; 68.55.Ik 相似文献
999.
Lee BS Chi YS Lee JK Choi IS Song CE Namgoong SK Lee SG 《Journal of the American Chemical Society》2004,126(2):480-481
Self-assembled monolayers presenting imidazolium ions at the tail ends (SAMIMs) having different counteranions have been prepared on Au, and the measurement of water contact angles of the surfaces proved to be an extremely valuable simple technique for quantifying the effects of counteranions on hydrophilicity and hydrophobicity of SAMIMs, which will be extrapolated to the water miscibility of the related ionic liquids. 相似文献
1000.