Preparación y caracterización de compuestos poliméricos a base de aceite de linaza epoxidado y nanotubos de carbono

Establecer las condiciones de preparación de compuestos poliméricos a base de aceite de linaza y nanotubos de carbono no modificados y modificados químicamente, y llevar a cabo su caracterización por FT-IR, SEM, propiedades eléctricasSe alcanzó el objetivo del proyecto. Se analizó el efecto de la funcionalización de nanotubos de carbono de pared múltiple (NTCPM) en la dispersión en una matriz polimérica. Esa dispersión se evaluó indirectamente mediante la medición de la resistencia eléctrica y posterior cálculo de la resistividad de películas de los compuestos poliméricos a base de Aceite de linaza epoxidado (ALE) y NTCPM sin modificar y modificados superficialmente por oxidación química, a diferentes composiciones de NTCPM. El método de dispersión y la observación cualitativa de ésta, se realizó como se estableció en la metodología, observando cada hora, en diferentes disolventes, un concentración dada de NTCPM , en un microscopio óptico. Se determinó como el tiempo de dispersión adecuado, aquel en donde se observaron en mayoría, NTCPM individuales, siendo el mejor disolvente la Dimetil Formamida (DMF). El tiempo varió acorde al tipo de NTC empleados. Con los datos de resistividad, se construyeron las curvas de percolación de las tres series de compuestos generadas y se modeló la concentración crítica

Formation of b-Bi2O3 and d-Bi2O3 during laser irradiation of Bi films studied in-situ by spatially resolved Raman spectroscopy

The formation of different phases of Bi2O3 induced by laser irradiation of Bi films has been assessed in situ by micro-Raman spectroscopy as a function of laser wavelength, power density and irradiation time. Raman mapping of the irradiated samples enabled a spatially-resolved study of the distribution of the formed Bi2O3 phases. Red laser (633 nm) irradiation was found to induce the appearance of b-Bi2O3, within a certain range of power densities, by diffusion-controlled processes. In contrast, ultraviolet (UV, 325 nm) laser irradiation, above a certain power density threshold, initially induces the formation of both b and d-Bi2O3 phases. The amount of the produced d-Bi2O3 phase increases by increasing the irradiation time, while that of the b phase follows the opposite trend. UV laser irradiation seems to be a suitable method to produce room temperature stable d-Bi2O3 patterns on Bi film

Femtosecond laser-induced periodic surface structures formation on bismuth thin films upon irradiation in ambient air

ARTICULO DE INVESTIGACIÓNARTICULO DE INVESTIGACIÓ

Temas selectos en ciencia de materiales i (pdf)

Se presentan una selección de 12 capítulos de diferentes investigadores , los temas de esta obra se encuentran relacionados con polímeros y sus compuestos, nanoestructuras metálicas y óxidos metálicos.El presente libro de investigación tiene como objetivo difundir a la comunidad estudiantil de nivel licenciatura y posgrado, principalmente, algunos temas de actualidad en el campo de Ciencia de Materiales, para motivarla e interesarla en esa área tan importante. Se espera también que el libro sea de utilidad para estudiantes de posgrado en Ciencias e Ingeniería de Materiales o áreas afines

Effect of thermal treatment on Zn nanodisks

Artículo asociado a tesis de Doctorado del estudiante Pedro Estanislao Acuña AvilaMetallic Zn nanodisks with hexagonal morphology were obtained onto glass sub- strate under vacuum thermal evaporation. A thermal characterization of Zn nanodiks showed a lower oxidation temperature than source powder Zn. Different thermal treatment on Zn nanodisks played an important role on the morphology, crystal size and surface vibrational modes of ZnO. The growth of ZnO nanoneedles started at the edge of metallic zinc hexagonal structures according with SEM images, the higher temperature the longer needles were grown. XRD diffractogram confirmed the wurtzite structure of ZnO with metallic nuclei. A wide band between 530 and 580 cm−1 of Raman scattering corresponded at surface vibrational modes not observed at higher temperatur

Ether gas-sensor based on Au nanoparticles-decorated ZnO microstructures

Trabajo de Investigación derivado de la estancia Posdoctoral del Dr. Roberto LópezAn 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 1025/2014RIF

Population based prostate cancer screening in north Mexico reveals a high prevalence of aggressive tumors in detected cases

Background: Prostate Cancer (PCa) is the second most frequent neoplasia in men worldwide. Previous reports suggest that the prevalence of PCa in Hispanic males is lower than in Africans (including communities with African ancestry) and Caucasians, but higher than in Asians. Despite these antecedents, there are few reports of open population screenings for PCa in Latin American communities. This article describes the results of three consecutive screenings in the urban population of Monterrey, Mexico. Methods: After receiving approval from our University Hospital's Internal Review Board (IRB), the screening was announced by radio, television, and press, and it was addressed to male subjects over 40 years old in general. Subjects who consented to participate were evaluated at the primary care clinics of the University Health Program at UANL, in the Metropolitan area of Monterrey. Blood samples were taken from each subject for prostate specific antigen (PSA) determination; they underwent a digital rectal examination (DRE), and were subsequently interviewed to obtain demographic and urologic data. Based on the PSA (>4.0 ng/ml) and DRE results, subjects were appointed for transrectal biopsy (TRB). Results: A total of 973 subjects were screened. Prostate biopsy was recommended to 125 men based on PSA values and DRE results, but it was performed in only 55 of them. 15 of these biopsied men were diagnosed with PCa, mostly with Gleason scores ≥ 7. Conclusion: Our results reflect a low prevalence of PCa in general, but a high occurrence of high grade lesions (Gleason ≥ 7) among patients that resulted positive for PCa. This observation remarks the importance of the PCa screening programs in our Mexican community and the need for strict follow-up campaigns

Population based prostate cancer screening in north Mexico reveals a high prevalence of aggressive tumors in detected cases

Background: Prostate Cancer (PCa) is the second most frequent neoplasia in men worldwide. Previous reports suggest that the prevalence of PCa in Hispanic males is lower than in Africans (including communities with African ancestry) and Caucasians, but higher than in Asians. Despite these antecedents, there are few reports of open population screenings for PCa in Latin American communities. This article describes the results of three consecutive screenings in the urban population of Monterrey, Mexico. Methods: After receiving approval from our University Hospital's Internal Review Board (IRB), the screening was announced by radio, television, and press, and it was addressed to male subjects over 40 years old in general. Subjects who consented to participate were evaluated at the primary care clinics of the University Health Program at UANL, in the Metropolitan area of Monterrey. Blood samples were taken from each subject for prostate specific antigen (PSA) determination; they underwent a digital rectal examination (DRE), and were subsequently interviewed to obtain demographic and urologic data. Based on the PSA (>4.0 ng/ml) and DRE results, subjects were appointed for transrectal biopsy (TRB). Results: A total of 973 subjects were screened. Prostate biopsy was recommended to 125 men based on PSA values and DRE results, but it was performed in only 55 of them. 15 of these biopsied men were diagnosed with PCa, mostly with Gleason scores ≥ 7. Conclusion: Our results reflect a low prevalence of PCa in general, but a high occurrence of high grade lesions (Gleason ≥ 7) among patients that resulted positive for PCa. This observation remarks the importance of the PCa screening programs in our Mexican community and the need for strict follow-up campaigns

Search for composite and exotic fermions at LEP 2

A search for unstable heavy fermions with the DELPHI detector at LEP is reported. Sequential and non-canonical leptons, as well as excited leptons and quarks, are considered. The data analysed correspond to an integrated luminosity of about 48 pb^{-1} at an e^+e^- centre-of-mass energy of 183 GeV and about 20 pb^{-1} equally shared between the centre-of-mass energies of 172 GeV and 161 GeV. The search for pair-produced new leptons establishes 95% confidence level mass limits in the region between 70 GeV/c^2 and 90 GeV/c^2, depending on the channel. The search for singly produced excited leptons and quarks establishes upper limits on the ratio of the coupling of the excited fermio

Search for lightest neutralino and stau pair production in light gravitino scenarios with stau NLSP

Promptly decaying lightest neutralinos and long-lived staus are searched for in the context of light gravitino scenarios. It is assumed that the stau is the next to lightest supersymmetric particle (NLSP) and that the lightest neutralino is the next to NLSP (NNLSP). Data collected with the Delphi detector at centre-of-mass energies from 161 to 183 \GeV are analysed. No evidence of the production of these particles is found. Hence, lower mass limits for both kinds of particles are set at 95% C.L.. The mass of gaugino-like neutralinos is found to be greater than 71.5 GeV/c^2. In the search for long-lived stau, masses less than 70.0 to 77.5 \GeVcc are excluded for gravitino masses from 10 to 150 \eVcc . Combining this search with the searches for stable heavy leptons and Minimal Supersymmetric Standard Model staus a lower limit of 68.5 \GeVcc may be set for the stau mas