15 research outputs found
Análisis de Pulpa y Aceite de Aguacate con Espectroscopia Infrarroja
Attenuated total reflectance with infrared spectroscopy
has revolutionized the instrumental analysis for a
variety of materials, including those of biological
origin. Applications are focused to identification and
quantification of chemical compounds, detection
of changes at molecular level and evaluate the
authenticity of a product. The objective of this research
was to analyze pulp and oil from avocado by infrared
spectroscopy. The pulp showed several absorption
bands centered at 1653 cm-1 assigned to the vibration
of extensive type C=O (amide I in proteins), 1547 cm-1
(N-H bending, amide II), and 1237 cm-1 (N-H bending,
amide III). The spectrum of avocado oil showed C-H
groups in the range at 3000 to 2800 cm-1, and an
intense band at 1744 cm-1 attributed to C=O, extensive
vibrations of carbonyl group in esters. From the latter
group of frequency, the ratio of absorbance intensities
between 3007 cm-1 (band extended unsaturated =C-H)
and absorbance at 2924 cm-1 (extended-band C-H),
was used to estimate the iodine value of oil, it was 74.8
within the range of 69 to 95, obtained by chemical tests.La espectroscopia infrarroja con reflectancia total
atenuada ha revolucionado los análisis instrumentales
en diversos tipos de materiales, incluyendo los de origen
biológico. Las aplicaciones se enfocan a identificación,
cuantificación de compuestos quÃmicos, detección de
cambios a nivel molecular y contrastar la autenticidad
de un producto. El objetivo de esta investigación fue
analizar la pulpa y aceite de aguacate por medio de la
espectroscopia infrarroja. Para la pulpa se observaron
varias bandas de absorción centradas en 1653 cm-1,
asignada a la vibración de tipo extensiva C=O (amida
I de las proteÃnas), 1547 cm-1 (N�H flexión, amida II),
y 1237 cm-1 (N�H flexión, amida III). El espectro del
aceite de aguacate extraÃdo muestra los grupos C�H,
en el rango 3000 a 2800 cm-1, y una banda intensa en
1744 cm-1 atribuida al enlace C=O, vibraciones de
extensión del grupo éster carbonilo. Del último grupo
de frecuencias, la relación de intensidades entre la
absorbancia en 3007 cm-1 (banda extensiva insaturada
=C�H) y la absorbancia en 2924 cm-1 (banda extensiva
�C�H), fue utilizada para estimar el valor del Ãndice de
yodo del aceite, éste fue 74.8, valor dentro del rango de
69 a 95, obtenido mediante pruebas quÃmicas
Nonlocal nonlinear refractive index of gold nanoparticles synthesized by ascorbic acid reduction: comparison of fitting models
Guiding light with singular beams in nanoplasmonic colloids
We investigate the nonlinear propagation of light beams with complex phase and intensity structures, including a Gaussian-embedded vortex, a Bessel vortex, and a Bessel-cosine necklace. We employ a colloidal suspension of bio-synthesized plasmonic gold nanoparticles, where a self-defocusing response is mediated by absorption at the laser wavelength (532 nm). We show that, by means of nonlocal nonlinearity, these structured two-dimensional beams with on-axis singularity can counteract the diffraction of the dark core and guide therein a coaxial Gaussian probe of different wavelengths (633 nm) and lower intensities. Angular steering of the confined probe is also demonstrated by tilting the propagation direction of the pump