16 research outputs found
El dinero en la actividad económica en Puerto Rico: Una aplicación de la prueba de causalidad de Granger
No full textSinopsis de las siguientes tesis: Segmentación R-square: ¿Un nuevo instrumento para la inversión?; El uso de la teoría del arbitraje en determinar la prima de riesgo específica de cada industria; Relationship Marketing: La Nueva Tendencia en Mercadeo y Cómo es Aplicada por los Distribuidores de Bienes de Consumo en Puerto Rico; La calidad en los servicios de telecomunicaciones ofrecidos al pueblo de Puerto Rico por la Telefónica de Puerto Rico; El impacto de las leyes del FDIC en los sistemas de respaldo para las instituciones financieras; El dinero en la actividad económica en Puerto Rico: Una aplicación de la prueba de causalidad de Granger
MATRIX ISOLATION STUDY OF THE PRODUCTS OF THE REACTION OF TRIMETHYLALUMINUM WITH LEWIS BASES
No full textAuthor Institution: Department of Chemistry, University of CincinnatiTrimethylaluminum is a key reagent in the synthesis of aluminum-containing thin films, including aluminum nitride. The matrix isolation technique has been combined with infrared spectroscopy to investigate intermediates formed in several of these reactions. The initial reaction of ( with in argon matrices leads to the 1:1 adduct ( in very high yield. The spectrum of this complex was very intense, and different than the spectrum of the complex in the solid state. Pyrolysis of ( mixtures prior to matrix deposition led to a decrease in yield or the adduct, and the production of . However, no additional intermediate species were detected. Analogous reactions of ( with are currently under investigation, and will be reported
Characterization of infrared matrix-assisted laser desorption ionization samples by Fourier transform infrared attenuated total reflection spectroscopy
No full textFourier transform infrared attenuated total reflection (FT-IR ATR) spectroscopy was used to characterize thin films of succinic acid, a matrix compound commonly used with infrared matrix-assisted laser desorption ionization (IR-MALDI) mass spectrometry. IR spectra of succinic acid thin films deposited alone and in combination with the analyte biomolecules insulin and cytochrome c were obtained by FT-IR ATR spectroscopy. Spectra of analyte and matrix alone were similar to those obtained previously from KBr pellets, Nujol mull, or thin-film absorption, although the ATR spectra have significantly lower background interferences. Thin films deposited from mixtures of water and methanol have additional peaks compared to films deposited from a methanol solution. These additional peaks are attributed to carboxylate groups stabilized by residual water molecules. No evidence was found to suggest that residual water absorption contributes to absorption at wavelengths typically used for IR-MALDI. Absorption of energy by analyte vibrational modes with rapid energy transfer to the matrix is suggested as a contributor to desorption and ionization consistent with the FT-IR ATR results
Matrix isolation and ab initio study of the reactions of (CH3)3Al with CH3OH and H2O: spectroscopic evidence for (CH3)2AlOCH3
No full textMatrix isolation study of the 1:1 molecular complexes of (CH3)3Al with group V and VI bases
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Study of an ARS-like function of map units 88-100 of parvovirus LUIII
No full textThe synthesis of minus strand by parvovirus LuIII requires replication from the
left palindrome of the plus strand DNA. An origin of replication yet to be identified must
be present at the right end of the minus strand, required for the synthesis of plus
strand. Parvovirus LuIII contains a unique A/T-rich sequence that shares a sequence
homology with the autonomously replicating sequences (ARS) found in yeast. To test
if the A/T rich region and sequences downstream the A/T sequence are responsible
for autonomous replication, nucleotides 4527 to 5135 of LuIII were cloned (pUraLu88-
100) into a vector containing the URA3 gene as an auxotrophic marker. pUra-Lu88-
100 was transformed into Saccharomyces cerevisiae (SEY S288C,ura3-) by the
electroporation method. Plasmid DNA was isolated from the resulting colonies and
transformed into Echerichia coli DH5α cells. Analysis performed to the plasmid
rescued from yeast indicate that pUra-Lu88-100 was capable of existing in a free state
in S. cerevisiae, suggesting that the elements required for a limited ARS-like function
are present in at the right end of the LuIII viral genome.La síntesis de la hebra negativa por el parvovirus LuIII requiere la replicación
del palindrome izquierdo de la hebra positiva de ADN. Un origen de replicación que
no a sido identificado debe estar presente en el extremo derecho de la hebra
negativa. El parvovirus LuIII contiene una secuencia única rica en A/T que comparte
homología con las secuencias de replicación autónoma encontradas en levaduras.
Para evaluar si la región rica en A/T y las secuencias río abajo de ésta son
responsables de replicación autónoma, los nucleotidos 4527 a 5135 de LuIII fueron
clonados (pUraLu88-100) en un vector que contenía el gene URA3 como un
marcador auxotrófico. pUra-Lu88-100 fue transformado en el S. cerevisiae (SEY
S288C, ura3 -) por el método de electroporación. El ADN del plásmido fue aislado de
las colonias resultantes y transformado posteriormente en células del E. coli DH5α.
Análisis realizados al plásmido rescatado de la levadura indican que el clon pUra-
Lu88-100 fue capaz de existir en un estado libre en S. cerevisiae, sugiriendo que los
elementos requeridos para llevar a cabo replicación autónoma limitada similar a la
descrita para ARS están presentes en el terminal derecho del genoma viral de LuIII.200
Particle formation by infrared laser ablation of glycerol: implications for ion formation
No full textThe quantity and size distribution of micrometer-sized particles ejected from thin films of glycerol were measured using light scattering particle sizing. Thin glycerol films were irradiated at atmospheric pressure with an infrared optical parametric oscillator at wavelengths between 2.95 and 3.1 μm. Particulate material resulting from the ablation was sampled directly into a particle-sizing instrument and particles with diameters greater than 500 nm were detected and sized by light scattering. The fluence threshold for particle formation was between 2000 and 3000 J/m2 for all laser wavelengths. At threshold, fewer than 100 particles/cm3 were detected and this value increased to several thousand particles/cm3 at twice the threshold fluence. The average size of the coarse particles ranged from 900 nm to 1.6 μm at threshold and decreased by 10-20% at twice the threshold fluence. The coarse particle formation observations were compared with ion formation behavior in matrix-assisted laser desorption ionization and interpreted in terms of a photomechanical mechanism for material ablation and ion formation. Copyright © 2006 John Wiley & Sons, Ltd
