Author: ALFREDO SÁNCHEZ LÓPEZ
"La investigación se realizó con el propósito de conocer los efectos de prohexadiona–Ca en los niveles de giberelinas y citocininas endógenas en híbridos experimentales de tomate (Lycopersicon esculentum Mill.) tipo saladette con hábito de crecimiento determinado e indeterminado. Se aplicó el retardante de crecimiento a plantas de tomate en invernadero cuando estas alcanzaron 12 hojas verdaderas a concentraciones de 0 (testigo), 175 y 250 mg·litro-1. Las dosis de P-Ca utilizadas, redujeron los niveles de giberelinas y aumentaron las citocininas en meristemos apicales. En estos tejidos se identificaron las giberelinas A12 y A20 así como zeatina. En ápices testigo se encontraron giberelinas A1, A4 y A7, además de zeatina."
"The present research was conducted with the purpose to learn on the effects of prohexadione – Ca on the endogenous gibberellins and cytokinins levels in two experimental saladette tomato hybrids (Lycopersicon esculentum Mill.) with determinate and indeterminate growth habit. The concentrations of P-Ca used, have reduced in apical meristems the levels of gibberellins and have increased the cytokinins content. In these tissues, gibberellins A12, A20 and zeatin were identified. In control samples gibberellins A1, A4, A7 and zeatin were found."
Non-stoichiometric silicon oxide (SiOx) with embedded Si nanoparticles (Si-nps) shows novel physical characteristic, which permits its use in optoelectronic devices as photodetectors and light emitters. In this work, a detailed analysis of the structural and optical properties of silicon rich oxide films deposited via hot filament chemical vapor deposition is done. SiOx films with different Si content were obtained at different hydrogen flow. FTIR spectra show vibrational bands related to the presence of hydrogen in as-deposited SiOx films. This band is more intense as the hydrogen flow is increased, but disappears after thermal annealing. SiOx films exhibit a broad photoluminiscence (PL) spectra with main peaks at 700 and 750 nm. The PL band at 700 nm is enhanced as the hydrogen content in the SiOx films is increased. XPS spectra show a high Si concentration and a low oxygen concentration in the SiOx films. Transmittance spectra have a shifted to high wavelength after thermal annealing, and optical band gap was from 2.34 to 3.95 eV.
Biogenic Silver Nanoparticles as Sensors of Cu2+ and Pb2+ in Aqueous Solutions
Silver nanoparticles (Ag-NPs) were bio-synthesized using Camellia sinensis (green tea) aqueous extract. Nanoparticles prepared with 10-3 M AgNO3 solution, using 3mL of green tea extract and at 60˚C, have spherical shape with a mean diameter of 7nm. The formation of the nanoparticles was confirmed by UV-Vis spectrophotometry through studies of the surface plasmon resonance (SPR). The morphology, size and crystalline structure of the Ag-NPs were determined using high definition transmission electron microscopy (TEM). Moreover, these green synthesized Ag-NPs were found to exhibit good sensing properties towards Cu2+ and Pb2+ ions in aqueous solutions. This metal ions-sensing ability of the biogenic Ag-NPs was monitored by UV-Vis spectrophotometry (SPR analyses) and fluorescence spectroscopy.
En este trabajo se prepararon biocompositos de nanopartículas de plata utilizando fibra de algodón como soporte y Camellia sinensis como agente reductor. Para la preparación de los biocompositos primero se llevó a cabo la inmersión de fibras de algodón cargadas aniónicamente en una solución de iones de plata. Posteriormente se hizo una segunda inmersión de las fibras en una solución de Camellia sinensis. Los biocompositos obtenidos se caracterizaron por espectroscopia infrarroja para determinar cambios estructurales en la celulosa. Las fibras fueron observadas por las técnicas Microscopía Electrónica de Barrido de Emisión de Campo (FE-SEM) y Microscopia Electrónica de Transmisión de Emisión de Campo (FE-TEM) para determinar la impregnación de la superficie con las nanopartículas de plata y la distribución de tamaño de las mismas, obteniendo tamaños promedio de 5 y 11nm para dos diferentes muestras. Finalmente se determinaron las energías de enlace de la plata reducida por la técnica de Espectroscopia Fotoelectrónica de Rayos X (XPS), la cual mostro que se encontraban presentes en la fibra plata metálica (Ag0) y un complejo formado por plata y oxigeno (Ag-O).
Trabajo de Investigación derivado de la estancia Posdoctoral del Dr. Roberto López
An ether gas-sensor was fabricated based on gold nanoparticles (Au-NPs) decorated zinc oxide microstructures (ZnO-MS). Scanning electron microscope (SEM) and high-resolution transmission elec- tron microscope (HRTEM) measurements were performed to study morphological and structural proper- ties, respectively, of the ZnO-MS. The gas sensing response was evaluated in a relatively low temperature regime, which ranged between 150 and 250 C. Compared with a sensor fabricated from pure ZnO-MS, the sensor based on Au-NPs decorated ZnO-MS showed much better ether gas response at the highest working temperature. In fact, pure ZnO-MS based sensor only showed a weak sensitivity of about 25%. The improvement of the ether gas response for sensor fabricated with Au-NPs decorated ZnO-MS was attributed to the catalytic activity of the Au-NPs.
Investigación realizada bajo proyecto UAEM 1025/2014RIFC
It is well known that silicon-rich oxide (SRO) shows intense photoluminescence (PL). In this work, the authors studied the relationship of the surface morphology and the PL emission. PL spectra of SRO as a function of the excess silicon, temperature, and time of thermal annealing were obtained. The same samples were studied using transmission electronic microscopy and atomic force microscopy to determine their microstructure and surface morphology. A relationship between silicon agglomerates in the SRO and the surface morphology was obtained. Then, the red PL emission was related to the surface morphology. The authors found that the surface roughness is an important parameter for the high red emission of SRO.
"The chemical interaction between biogenic gold nanoparticles (AuNPs) and several metal (II) ions can be regarded as a practical, twofold, colorimetric, and plasmon resonance sensing method for the recognition of some divalent metal ions in aqueous solutions. The green synthesized AuNPs, using Camellia sinensis as a reducing agent, were characterized by a surface plasmon resonance (SPR) using UV-Vis spectroscopy, infrared spectroscopy, and transmission electron microscopy. The AuNP colloidal solutions obtained have a pink-reddish color with SPRs centered between 529 and 536nm. AuNPs with spherical, triangular, and hexagonal shapes were found by TEM analyses. Despite their divergent morphologies, these AuNPs can be employed as colorimetric and plasmon resonance sensors for detection of Ca2+, Sr2+, Cu2+, and Zn2+, primarily, in aqueous solutions. Sensibility studies based on molar concentrations were also performed for these metal ions. Furthermore, solid biogenic AuNPs/cellulosic biocomposites were prepared with the aim of developing portable, fast, and dependable colorimetric sensors; nevertheless, these biocomposites resulted to be good adsorbent materials of metal ions."
RAUL ALBERTO MORALES LUCKIE Víctor Sánchez Mendieta Oscar F. Olea-Mejia ALFREDO RAFAEL VILCHIS NESTOR GUSTAVO LOPEZ TELLEZ VICTOR VARELA GUERRERO LAZARO HUERTA ARCOS JESUS ANGEL ARENAS ALATORRE (2013)
SINTESIS DE NANOPARTICULAS
Silver nanoparticles were synthesized and supported on thin nylon membranes by means of a simple method of impregnation and chemical reduction of Ag ions at ambient conditions. Particles of less than 10nm were obtained using this methodology, in which the nylon fibers behave as constrained nanoreactors. Pores on nylon fibres along with oxygen and nitrogen from amide moieties in nylon provide effective sites for in situ reduction of silver ions and for the formation and stabilization of Ag nanoparticles. Transmission electron microscopy (TEM) analysis showed that silver nanoparticles are well dispersed throughout the nylon fibers. Furthermore, an interaction between
Research Article Plasmonic Sensing of Aqueous-Divalent Metal Ions by Biogenic Gold Nanoparticles
The chemical interaction between biogenic gold nanoparticles (AuNPs) and several metal (II) ions can be regarded as a practical, twofold, colorimetric, and plasmon resonance sensing method for the recognition of some divalent metal ions in aqueous solutions. The green synthesized AuNPs, using Camellia sinensis as a reducing agent, were characterized by a surface plasmon resonance (SPR) using UV-Vis spectroscopy, infrared spectroscopy, and transmission electron microscopy. The AuNP colloidal solutions obtained have a pink-reddish color with SPRs centered between 529 and 536 nm. AuNPs with spherical, triangular, and hexagonal shapes were found by TEM analyses. Despite their divergent morphologies, these AuNPs can be employed as colorimetric and plasmon resonance sensors for detection of Ca2+, Sr2+, Cu2+, and Zn2+, primarily, in aqueous solutions. Sensibility studies based on molar concentrations were also performed for these metal ions. Furthermore, solid biogenic AuNPs/cellulosic biocomposites were prepared with the aim of developing portable, fast, and dependable colorimetric sensors; nevertheless, these biocomposites resulted to be good adsorbent materials of metal ions.
Este artículo describe una metodología de planificación, localización y mapeo simultáneos enfocada en el problema de localización global, el robot explora el ambiente eficientemente y también considera los requisitos de un algoritmo de localización y mapeo simultáneos. El método está basado en la generación aleatoria incremental de una estructura de datos llamada árbol aleatorio basado en sensores, la cual representa un mapa de caminos del área explorada con su región segura asociada. Un procedimiento de localización continuo basado en características B-splines de la región segura se integró en el esquema.
This paper describes a simultaneous planning localization and mapping (SPLAM) methodology focussed on the global localization problem, where the robot explores the environment efficiently and also considers the requisites of the simultaneous localization and mapping algorithm. The method is based on the randomized incremental generation of a data structure called Sensorbased Random Tree, which represents a roadmap of the explored area with an associated safe region. A continuous localization procedure based on B-Splines features of the safe region is integrated in the scheme.