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Gayou V.L.,Autonomous University of the State of Morelos | Salazar-Hernandez B.,Autonomous University of the State of Morelos | Rojas-Lopez M.,Research Center en Biotecnologia Aplicada del | Islas C.Z.,National Institute of Astrophysics, Optics and Electronics | Ascencio J.A.,National Autonomous University of Mexico
Journal of Nano Research | Year: 2010

Doped ZnS nanocrystals have attracted attention since 1994. Previous results suggest that doped semiconductor nanocrystals form a new class of luminescent materials, which have a wide range of applications in displays, lighting, sensors and lasers. In this work we synthesized Y3+ doped ZnS nanoparticles by a chemical precipitation method. The reaction was performed with ZnSO 4, Na 2S, phosphates and Yttrium acetate in aqueous solution. Fluorescence (FL) studies of these nanoparticles have been carried out. FL analysis reveals that the incorporation of Yttrium and phosphates to colloidal solution of ZnS nanoparticles enhances the FL signal by 6-7 times of magnitude compared with uncapped ZnS nanoparticles. © (2010) trans Tech Publications, Switzerland. Source


Herrera-Celis J.,National Institute of Astrophysics, Optics and Electronics | Reyes-Betanzo C.,National Institute of Astrophysics, Optics and Electronics | Itzmoyotl-Toxqui A.,National Institute of Astrophysics, Optics and Electronics | Orduna-Diaz A.,Research Center en Biotecnologia Aplicada del | Perez-Coyotl A.,Research Center en Biotecnologia Aplicada del
Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films | Year: 2015

The characterization of a-SixC1-x:H thin films by plasma-enhanced chemical vapor deposition with high hydrogen dilution for biological applications is addressed. A root mean square roughness less than 1-nm was measured via atomic force microscopy for an area of 25-μm2. Structural analysis was done using Fourier transform infrared spectroscopy in the middle infrared region. It was found that under the deposition conditions, the formation of Si-C bonds is promoted. Electrical dark conductivity measurements were performed to evaluate the effect of high hydrogen dilution and to find the relation between carrier transport properties and the structural arrangement. Conductivities of the order of 10-7 to 10-9 S/cm at room temperature for methane-silane gas flow ratio from 0.35 to 0.85 were achieved, respectively. UV-visible spectra were used to obtain the optical band gap and the Tauc parameter. Optical band gap as wide as 3.55-eV was achieved in the regime of high carbon incorporation. Accordingly, deposition under low power density and high hydrogen dilution reduces the roughness, improves the structure of the network, and stabilizes the film properties as a greater percentage of carbon is incorporated. The biofunctionalization of a-SixC1-x:H surfaces with NH2-terminated self-assembled monolayers was obtained through silanization with 3-aminopropyltrimethoxysilane. This knowledge opens a window for the inclusion of these a-SixC1-x:H thin films in devices such as biosensors. © 2015 American Vacuum Society. Source


Gayou V.L.,Research Center en Biotecnologia Aplicada del | Gayou V.L.,Autonomous University of the State of Morelos | Salazar-Hernandez B.,Autonomous University of the State of Morelos | Macuil R.D.,Research Center en Biotecnologia Aplicada del | And 3 more authors.
Journal of Nano Research | Year: 2010

Zinc sulfide (ZnS), a representative of wide band gap semiconductor nanocrystals, has an excitonic Bohr radius (aBZnS) of 2.5 nm. It makes ZnS nanoparticles (ZnS NP) having such size very interesting as small biomolecular probes for fluorescence and laser scanning microscopy. To date, ZnS NP of diameters larger than aBZnS has been subject of extensive experimental and theoretical studies. However many questions remain open concerning the synthesis of undoped and uncapped ZnS NP of diameters less than 2.5 nm. To further probe into the physical properties of undoped and uncapped ZnS NP, in this work we report on studies of uncapped ZnS nanoparticles synthesized by a wet chemical process at room temperature. Three colloidal suspensions (named A, B and C, respectively) were obtained from 9:1, 1:1 and 1:9 volume mixtures of 1mM ZnSO4 and 0.85mM Na2S aqueous solutions. Qualitative differences in UV-Vis absorption spectra are discussed in the context of Z-contrast scanning transmission electron microscopy (Z-contrast), low and high resolution transmission electron microscopy (TEM) results. Distribution of particle size is dependent on different volumes of source solutions. For the intermediate mixture, it has been found that about 78% of ZnS nanoparticles have a diameter smaller than the excitonic Bohr Radius of 2.5 nm. HRTEM studies have revealed that nanoparticles grow preferentially with hexagonal structure. © (2010) trans Tech Publications, Switzerland. Source


Cortes-Espinosa D.V.,Research Center en Biotecnologia Aplicada del | Absalon A.E.,Research Center en Biotecnologia Aplicada del | Sanchez N.,Research Center en Biotecnologia Aplicada del | Loera O.,Metropolitan Autonomous University | And 2 more authors.
Journal of Molecular Microbiology and Biotechnology | Year: 2011

A strain of Aspergillus niger, previously isolated from sugarcane bagasse because of its capacity to degrade phenanthrene in soil by solid culture, was used to express a manganese peroxidase gene (mnp1) from Phanerochaete chrysosporium, aiming at increasing its polycyclic aromatic hydrocarbons degradation capacity. Transformants were selected based on their resistance to hygromycin B and the discoloration induced on Poly R-478 dye by the peroxidase activity. The recombinant A. niger SBC2-T3 strain developed MnP activity and was able to remove 95% of the initial phenanthrene (400 ppm) from a microcosm soil system after 17 days, whereas the wild strain removed 72% under the same conditions. Transformation success was confirmed by PCR amplification using gene-specific primers, and a single fragment (1,348 bp long, as expected) of the recombinant mnp1 was amplified in the DNA from transformants, which was absent from the parental strain. Copyright © 2012 S. Karger AG, Basel. Source


Delgado-Macuil R.J.,Research Center en Biotecnologia Aplicada del | Rojas-Lopez M.,Research Center en Biotecnologia Aplicada del | Gayou V.L.,Research Center en Biotecnologia Aplicada del | Orduna-Diaz A.,Research Center en Biotecnologia Aplicada del | And 2 more authors.
Materials Research Society Symposium Proceedings | Year: 2010

In this work we used the Fourier Transform Infrared spectroscopy and UV/Vis spectroscopy to analyze the behaviour of self-ensemble films of spiropyran when the films were irradiated by UV. In UV/Vis spectroscopy is possible observe the generation of the absorption peak, at 575 nm, associated to the merocyanine state when the ring-opening process is induced by UV light. In ATR the kinetics of the ring-opening was determinate too; following the spectra changes in real time. © 2010 Materials Research Society. Source

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