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1.
Phys Chem Chem Phys ; 13(7): 2659-62, 2011 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-21180726

RESUMEN

The first-principles studies were performed for the modified graphites with various edge conformations, which revealed that the NH edge facilitates easy transfer of an electron into the adsorbed O(2).

2.
Anal Sci ; 24(2): 193-200, 2008 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-18270408

RESUMEN

Micromarkers with five photoluminescence colors were developed as tracers for shadowing pursuits. The markers are colorless powders with particle diameters of several tens to several hundreds of micrometers, prepared using a cryogenic sample crusher. They were visualized using red, green, yellow, magenta or cyan photoluminescence under ultraviolet light at approximately 365 nm. The markers were composed of photoluminescent compounds dispersed in polyvinyl butyral. The photoluminescent compounds in the polyvinyl butyral were stable under ambient conditions for more than one year after application. The compounds with the red, green, yellow, magenta and cyan photoluminescence contained a europium (Eu(3+)) complex, a terbium (Tb(3+)) complex, a mixture of Tb(3+) and Eu(3+) complexes, a mixture of Eu(3+) complex and o-coumaric acid, and a mixture of Tb(3+) complex and 7-hydroxycoumarin along with a few drops of a sodium bicarbonate aqueous solution, respectively. Neodymium (Nd(3+)) and ytterbium (Yb(3+)) complexes with photoluminescence in the near-IR wavelength region can also be added to these visible photoluminescent compounds as secret markers for discrimination. The markers were non-destructively identified using a microscopic FT-IR spectrometer and a microscopic spectrometer equipped with a fluorescence detector.


Asunto(s)
Colorantes Fluorescentes/química , Luminiscencia , Color , Ácidos Cumáricos/química , Europio/química , Neodimio/química , Tamaño de la Partícula , Fotoquímica , Bicarbonato de Sodio/química , Terbio/química , Umbeliferonas/química , Iterbio/química
3.
J Phys Chem B ; 109(43): 20415-23, 2005 Nov 03.
Artículo en Inglés | MEDLINE | ID: mdl-16853642

RESUMEN

The density functional theory (DFT) of the water-gas shift (WGS) reaction over molybdenum carbide was studied with the aim of understanding the dissociation of H(2)O, the OH group, and CO to determine on what sections of molybdenum carbide CO(2) and H(2) formed and whether they played a role in the reaction. The energy diagram of each elementary step, the reaction of the hydrogen and oxygen atoms with CO, and the transition state for this elementary step were also studied. The IR spectra of the CO adsorption was experimentally analyzed for the identification of several candidates of the CO adsorption modes. The adsorptions of the threefold Mo site (a) with and (b) without the underlying C atom of the second layer have the second and highest adsorption energies of -281.59 and -321.00 kJ/mol, respectively. The IR data showed that the bands at 1626 cm(-1) from the IR experiments are (a) the nearest adsorption of the threefold Mo site with the underlying C atom at the calculated/corrected band of 1621 cm(-1). The calculated/corrected threefold adsorption (b) had the highest adsorption energy but exhibited an IR band at 1147 cm(-1) which was not observed in the experimental data. The C-O bond length increased to 1.49 from 1.36 after the H(2)O adsorption (b), suggesting the dissociation of C-O after the H(2)O coadsorption. The WGS reaction on the beta-Mo(2)C(001) slab carbide was calculated and took place as follows: H(2)O was dissociated into OH and H on the Mo(2)C surface and the OH subsequently dissociated into H and O atoms. CO approached the O atom to form CO(2).


Asunto(s)
Molibdeno/química , Adsorción , Monóxido de Carbono , Gases , Modelos Moleculares , Conformación Molecular , Espectrofotometría Infrarroja , Agua
4.
Anal Sci ; 21(12): 1457-65, 2005 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-16379386

RESUMEN

Fatty acids in 42 types of saponified vegetable and animal oils were analyzed by electrospray ionization mass spectrometry (ESI-MS) for the development of their rapid discrimination. The compositions were compared with those analyzed by gas chromatography-mass spectrometry (GC-MS), a more conventional method used in the discrimination of fats and oils. Fatty acids extracted with 2-propanol were-detected as deprotonated molecular ions ([M-H]-) in the ESI-MS spectra of the negative-ion mode. The composition obtained by ESI-MS corresponded to the data of the total ion chromatograms by GC-MS. The ESI-MS analysis discriminated the fats and oils within only one minute after starting the measurement. The detection limit for the analysis was approximately 10(-10) g as a sample amount analyzed for one minute. This result showed that the ESI-MS analysis discriminated the fats and oils much more rapidly and sensitively than the GC-MS analysis, which requires several tens of minutes and approximately 10(-9) g. Accordingly, the ESI-MS analysis was found to be suitable for a screening procedure for the discrimination of fats and oils.


Asunto(s)
Grasas/química , Aceites/química , Espectrometría de Masa por Ionización de Electrospray/métodos , Ácidos Grasos/análisis , Cromatografía de Gases y Espectrometría de Masas/métodos
5.
Anal Sci ; 19(3): 451-4, 2003 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-12675358

RESUMEN

The emission spectra of luminescent trivalent europium (Eu3+) and terbium (Tb3+) complexes were measured using a microscope laser Raman spectrometer with a doubled Nd:YAG laser (532 nm) and an Ar laser (488 nm). Excitation at 532 and 488 nm corresponded to wavelengths of the 7F1 --> 5D1 band of Eu3+ and the 7F6 --> 5D4 band of Tb3+, respectively. The Eu3+ and Tb3+ complexes were discriminated by high-resolution emission spectra more distinctly and sensitively than by fluorescence spectrometry, the usual analytical method.

6.
J Forensic Sci ; 47(2): 244-53, 2002 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-11908591

RESUMEN

Identifiable fluorescent markers were developed as tracers to tail suspects using phenanthrene, anthracene, fluoranthene, pyrene, perylene, and coronene in vaseline. Vaseline was used as a carrier of the marker. Of the six compounds in the vaseline, perylene and fluoranthene were readily observed under ultraviolet (UV) light at a wavelength of 365 nm. All six compounds were identified selectively and sensitively without interference of vaseline using a high performance liquid chromatograph (HPLC) with a fluorescence detector. The detection limit was much less than 1 ng, corresponding to that of the observation behavior under UV light. The results showed that each component with vaseline was more effective than the individual component for the delay in degradation. The case examples of the fluorescent markers are shown.


Asunto(s)
Colorantes Fluorescentes/química , Medicina Legal/métodos , Hidrocarburos Policíclicos Aromáticos/química , Cromatografía Líquida de Alta Presión/métodos , Criminología/métodos , Colorantes Fluorescentes/análisis , Humanos , Vaselina , Hidrocarburos Policíclicos Aromáticos/análisis , Espectrometría de Fluorescencia/métodos , Robo/legislación & jurisprudencia , Rayos Ultravioleta
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