Fabricación de nanopartículas de oro dentro de óxido de aluminio (γ-Al2O3) nanoestructurado con cavidades esféricas

Manufacturing of Gold Nanoparticles within Nanostructured Aluminum Oxide (γ-Al2O3) with Spherical Cavities

Mariela de Jesús Franco Gallegos (2023, [Tesis de maestría])

Los catalizadores basados en nanopartículas de oro han generado gran interés, gracias a su capacidad de ser selectivos en la promoción de reacciones específicas o en la producción de productos deseados, minimizando la formación de productos secundarios no deseados; sus propiedades electrónicas únicas; y su utilización bajo condiciones ambientales. Sin embargo, la desventaja principal de los catalizadores de oro es la sinterización de las nanopartículas debido a su baja temperatura de fusión, lo que provoca la pérdida de actividad catalítica y la desactivación del catalizador. Una de lassoluciones que ofrece el uso de la nanociencia y la nanotecnología es la utilización de soportes nanoestructurados que den mejor estabilidad a las nanopartículas y las protejan de la desactivación. En este trabajo se sintetizaron catalizadores basados en nanopartículas de oro soportados y encapsulados en alúmina macroporosa, por un método de impregnación húmeda asistida por ultrasonido; un método sencillo, rápido y ecológico. El desempeño catalítico de materiales sintetizados se analizó mediante espectroscopía UV-Visible in-situ en la reducción de 4-Nitrofenol a 4-Aminofenol. Así mismo, se presentan las caracterizaciones por TEM, SEM, FT-IR, espectroscopía UV-Visible, y XRD de catalizadores obtenidos. Se obtuvieron catalizadores altamente activos con alto rendimiento gracias al uso de un soporte nanoestructurado.

Catalysts -based on gold nanoparticles have recently gained interest due to their ability to selectively promote specific catalytic reactions or produce desired products, while minimizing the formation of unwanted byproducts, their unique electronic properties, and their utilization under ambient conditions. However, the main drawback of gold catalysts is the sintering of nanoparticles due to their low melting temperature, which leads to loss of catalytic activity and catalyst deactivation. One of the solutions offered by nanoscience and nanotechnology is the use of nanostructured supports that provide better stability to the nanoparticles and protect them from deactivation. In this work, gold nanoparticle-based catalysts supported and encapsulated in macroporous alumina were synthesized using a simple, fast, and eco-friendly method of ultrasound-assisted wet impregnation. The catalytic performance of synthetized materials was evaluated by in-situ UV-Visible spectroscopy in the reduction of 4-Nitrophenol to 4-Aminophenol. In addition, their characterization by TEM, SEM, FT-IR, UV Visible spectroscopy and XRD are presented. Highly active catalysts with high performance were obtained thanks to the use of a nanostructured supports.

nanopartículas de oro, alúmina macroporosa, impregnación, reducción 4-NF gold nanoparticles, macroporous alumina, impregnation, 4-NF reduction INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS TECNOLOGÍA DE MATERIALES PROPIEDADES DE LOS MATERIALES PROPIEDADES DE LOS MATERIALES

Synthesis of Ferroelectric and Multiferroics Thin films of BiMnO3/ SrTiO3 and Structural, Piezoelectric, Magnetic, Optical, and Mechanical Properties Characterization

Glory Valentine Umoh (2022, [Tesis de doctorado])

Multiferroic characteristics of BiMnO3 thin films offer great prospects to explore, either

in terms of ferroelectricity, ferromagnetism, or ferroelasticity. Ferroelectric and

ferromagnetic materials can be used in data storage due to their electrical and magnetic

properties. Ferroelastic can find its application in microelectromechanical systems

devices. This dissertation focused on the synthesis, characterization, and improvement of

the multiferroic properties of polycrystalline BiMnO3 thin films as well as the elaboration

influence of Cu on the magnetism of BiMnO3 thin films. BiMnO3 films were grown on

three different substrates, Si (001), Pt-buffered Si (001), Nb-doped SrTiO3 (100), and also

doped with different amounts of Cu. The films were characterized using techniques such

as X-Ray diffraction (XRD), scanning electron microscope (SEM), HRTEM

observations, by energy-dispersive X-ray spectroscopy (EDS), atomic force microscopy

(AFM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Visible-near-IR

spectroscopy (Vis-NIR), electron energy loss spectrometer (EELS), nanoindenter,

superconductor quantum interference device (SQUID) magnetometer, and finally, the

polarization-electric field (P-E) hysteresis loops of the BiMnO3 thin films were conducted

at 200 and 300 K. There are several studies on the growth of thin films, however, they are

not clear and in some cases contradictory, therefore, different parameters were controlled

during the deposition in terms of working pressure, RF power, substrate, deposition

10

temperature, and target to substrate distance. After deposition ex-situ thermal treatment

was carried out in order to compensate for the volatility of bismuth and also to eliminate

secondary phase.

Kramer’s–Krӧnig analysis was used to determine bandgap, via a polynomial fit in the

energy loss function (ELF) plot with an Eg = 1.63 eV, complex dielectric function, and

static dielectric constant, ε* = 4.68 of the grown BiMnO3 thin films. The reflection

coefficient Ґl of the BiMnO3 thin films was used to elucidate the reflection loss in the

BiMnO3 thin films. XPS analysis revealed the existence of Mn charge transition of 3+

and 4+ states. Resistivity result describes BIMnO3 as a semiconductor. The

nanomechanical characterization demonstrated that the region of penetration depth was

below 10% of BiMnO3 film thickness. Young's modulus (E), hardness (H), and Stiffness

(S) were measured to be 142 ± 3 GPa, 8 ± 0.2 GPa, and 44072 ± 45 N/m respec

SÍNTESIS DE MATERIALES Materiales Multiferroicos CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA OTRAS ESPECIALIDADES FÍSICAS OTRAS OTRAS

Data for the synthesis, characterization, and use of xerogels as adsorbents for the removal of fluoride and bromide in aqueous phase

NAHUM ANDRES MEDELLIN CASTILLO ELIZABETH DIANE ISAACS PAEZ Liliana Giraldo Gutiérrez JUAN CARLOS MORENO-PIRAJAN ITZIA RODRIGUEZ MENDEZ SIMON YOBANNY REYES LOPEZ JAIME REYES HERNANDEZ SONIA JUDITH SEGOVIA SANDOVAL (2022, [Artículo])

"Groundwater with high fluoride concentrations has been recognized as one of the serious concerns worldwide. Besides, the fluoride released into the groundwater by slow dissolution of fluoride-containing rocks, various industries also contribute to fluoride pollution [1]. Excess intake of fluoride leads to various health problems such as dental and skeletal fluorosis, cancer, infertility, brain damage, thyroid diseases, etc. [2]. On the other hand, bromide is naturally present in surface and groundwater sources. However, during the chlorination process, bromide can be oxidized to HOBr, which can react with natural organic matter in water to form brominated organic disinfection byproducts, which are very harmful to human health [3]. Among various methods for water treatment, the adsorption process has been widely used and seems to be an efficient and attractive method for the removal of many contaminants in water, such as anions, in terms of cost, simplicity of design, and operation [4,5]. In the past years, xerogels and carbon xerogels, a new type of adsorbents, which are synthesized by the sol-gel polycondensation of resorcinol and formaldehyde, have gained attention due to their moldable texture and chemical properties [6]. Moreover, melamine addition in resorcinol and formaldehyde xerogels adds basic groups on its surface, favouring Lewis acid-base interactions between xerogels and other components by adsorption [7]. In this data article, the synthesis of three resorcinolformaldehyde (R/F) xerogels with an increasing amount of melamine (M) was carried out by colloidal polymerization (molar ratios of M/R = 0.5, M/R = 1.0, and M/R = 2.0). Additionally, samples of M/R = 0.5 xerogel were carbonized at 400, 450, and 550 degrees C under an inert atmosphere to increase their specific area. Organic and carbon xerogels obtained were characterized by FTIR, TGA, SEM, Physisorption of N 2, and the pH at the point of zero charge (pH PZC). All organic xerogels were also tested as adsorbents on the removal of fluoride and bromide ions from aqueous phase. The Freundlich, Langmuir, and Radke-Prausnitz isotherm models were applied to interpret the experimental data from adsorption equilibrium. Additionally, the data of the mass of the xerogel needed to remove fluoride and bromide from groundwater and fulfill the maximum concentration levels are also included."

Xerogels Melamine Colloidal polymerization Fluoride and bromide ions Adsorption BIOLOGÍA Y QUÍMICA QUÍMICA QUÍMICA

A comprehensive account of SARS-CoV-2 genome structure, incurred mutations, lineages and COVID-19 vaccination program

Shailendra Sharma deepmala sehgal Apekshita Singh Shailendra Goel SoomNath Raina (2022, [Artículo])

Corona Viruses Genome Structure Novel Mutations Resistance to Vaccines SARS-CoV-2 CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA COVID-19 ANTIBODY FORMATION LIFE CYCLE VACCINATION VACCINES LINEAGE

Tensile behavior of 3D printed polylactic acid (PLA) based composites reinforced with natural fiber

Eliana M Agaliotis BALTAZAR DAVID AKE CONCHA ALEJANDRO MAY PAT Juan Pablo Morales Arias Celina Bernal Alex Valadez González Pedro Jesús Herrera Franco Gwenaelle Proust JUAN FRANCISCO KOH DZUL José Gonzalo Carrillo Baeza Emmanuel Alejandro Flores Johnson (2022, [Artículo])

Natural fiber-reinforced composite (NFRC) filaments for 3D printing were fabricated using polylactic acid (PLA) reinforced with 1–5 wt% henequen flour comprising particles with sizes between 90–250 μm. The flour was obtained from natural henequen fibers. NFRCs and pristine PLA specimens were printed with a 0° raster angle for tension tests. The results showed that the NFRCs’ measured density, porosity, and degree of crystallinity increased with flour content. The tensile tests showed that the NFRC Young’s modulus was lower than that of the printed pristine PLA. For 1 wt% flour content, the NFRCs’ maximum stress and strain to failure were higher than those of the printed PLA, which was attributed to the henequen fibers acting as reinforcement and delaying crack growth. However, for 2 wt% and higher flour contents, the NFRCs’ maximum stress was lower than that of the printed PLA. Microscopic characterization after testing showed an increase in voids and defects, with the increase in flour content attributed to particle agglomeration. For 1 wt% flour content, the NFRCs were also printed with raster angles of ±45° and 90° for comparison; the highest tensile properties were obtained with a 0° raster angle. Finally, adding 3 wt% content of maleic anhydride to the NFRC with 1 wt% flour content slightly increased the maximum stress. The results presented herein warrant further research to fully understand the mechanical properties of printed NFRCs made of PLA reinforced with natural henequen fibers. © 2022 by the authors.

POLYLACTIC ACID (PLA) NATURAL FIBER HENEQUEN FIBER NATURAL FIBER REINFORCED COMPOSITE (NFRC) ADDITIVE MANUFACTURING 3D PRINTING MECHANICAL PROPERTY INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS TECNOLOGÍA DE MATERIALES PROPIEDADES DE LOS MATERIALES PROPIEDADES DE LOS MATERIALES

Validation of Novel spot blotch disease resistance alleles identified in unexplored wheat (Triticum aestivum L.) germplasm lines through KASP markers

suneel kumar UTTAM KUMAR Guriqbal Singh Dhillon Amit Singh Vinod Mishra Pradeep Kumar Bhati Saikat Das Ramesh Chand Kuldeep Singh Sundeep Kumar (2022, [Artículo])

Spot Blotch Genome-Wide Association Study Marker Trait Association KASP Markers Kompetitive Allele Specific PCR CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA TRITICUM AESTIVUM MATERIAL TRANSFER AGREEMENTS MARKER-ASSISTED SELECTION DISEASE RESISTANCE WHEAT

Preparation and characterization of strongly sulfonated acid block and random copolymer membranes for acetic acid esterification with 2-Propanol

Verónica Rosiles González Ronan Le Lagadec ARELLY PAULINA VARGUEZ CATZIM María Isabel de los Dolores Loría Bastarrachea Abigail Gonzalez Diaz EMANUEL HERNANDEZ NUÑEZ Manuel de Jesús Aguilar Vega MARIA ORTENCIA GONZALEZ DIAZ (2022, [Artículo])

In this paper, we report the synthesis of block and random copolymers of 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) and methyl methacrylate (MMA), with different AMPS feed ratios. These solution-processable copolymers with strongly sulfonated acid groups resulted in membranes with tunable ion exchange (IEC) and water absorption capacities. AFM images confirmed the microphase separation of PAMPS-b-PMMA-1:1 block copolymer membrane, annealed under the appropriate conditions. The resulting copolymers from the random combination of a 1:1 molar ratio of AMPS and MMA monomers are effective at enhancing the esterification conversion of acetic acid, when compared with a reaction catalyzed by PAMPS-b-PMMA block copolymers and the previously studied catalytic membranes. With the PAMPS-co-PMMA-1:1 membrane, the esterification reaction using acetic acid achieved 85% isopropyl acetate. These results are closely correlated with the increase in IEC (2.63 mmol H+ g−1 ) and the relationship between weight loss (20.3%) and swelling degree (68%) in 2-propanol. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

BLOCK COPOLYMERS RANDOM COPOLYMERS CATALYTIC MEMBRANES ESTERIFICATION ISOPROPYL ACETATE INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS TECNOLOGÍA DE MATERIALES PROPIEDADES DE LOS MATERIALES PROPIEDADES DE LOS MATERIALES

Metodología para el diseño y elaboración de material didáctivo interactivo sobre cultura del agua

Joaquín Flores Ramírez VICTOR ALEJANDRO SAINZ ZAMORA Rafael Val Segura Mario Buenfil (2015, [Documento de trabajo])

Se presentan los materiales didácticos desarrollados, a partir de una propuesta metodológica que considera fundamentos conceptuales, psicológicos y de comunicación.

Cultura del agua Material didáctico HUMANIDADES Y CIENCIAS DE LA CONDUCTA

Las patologías de los recubrimientos en muros y su repercusión en la salud respiratoria de los usuarios

Rosario Tovar (2023, [Tesis de doctorado])

251 páginas. Doctorado en Diseño Bioclimático.

El nivel de calidad del aire interior (CAI) tiene incidencia directa en la salud humana, por eso, es objeto de estudio del diseño bioclimático, toda vez que éste promueve el aprovechamiento de los factores ambientales para la creación y acondicionamiento de espacios en los que los usuarios experimenten confort y bienestar. Además, de impulsar la construcción con sentido común, en donde prevalezca el uso racional de los recursos y una baja dependencia energética. En la presente tesis se pudieron identificar las propiedades de los materiales más comunes que conforman los recubrimientos de muros (cal, cemento, mortero de cemento y yeso) para reconocer los que mejor se adaptan al clima en la Cd. de México, mismos que según se pudo constatar, contribuyen en el control de algunos factores de riesgo (físico: humedad, químico: tóxicos y biológico: microbios) relacionados con una baja calidad del aire al interior de las viviendas. Tal función mitiga o reduce la aparición de algunos de los padecimientos respiratorios más frecuentes en los usuarios como: alergias, asma, rinitis, gripe y sinusitis. Los análisis a los que fueron sometidos los recubrimientos de cuatro materiales ligantes, permitieron evaluar su desempeño ante factores ambientales semi-controlados (temperatura, humedad relativa y concentración de dióxido de carbono) inherentes al funcionamiento del propio espacio interior y al lugar de emplazamiento del mismo. Obviamente, todos los recubrimientos reaccionaron de forma distinta y acorde con las propiedades físicas y químicas de los materiales presentes en cada uno de ellos. Siendo las variaciones más representativas y satisfactorias, las relacionadas con la permeabilidad y el efecto biocida de los recubrimientos hechos con mezcla de cal. Las patologías que mostraron algunos recubrimientos a lo largo del periodo de monitoreo, debido a la insuficiente gestión de la humedad, al alto desarrollo microbiano y a la naturaleza química del material ligante, fueron criptoeflorescencias, moho, bacterias y desprendimiento/diseminación de partículas; mismas que se consideraron definitorias para establecer que al igual que los seres vivos, los materiales de construcción necesitan rangos higrotérmicos específicos, que permitan su óptimo estado de operación. En apego a lo anteriormente citado, es que se considera conveniente concientizar a la población en temas tan importantes para el bienestar social, como la selección de materiales y -consecuente- conservación de los recubrimientos de muros, no sólo para disminuir los costos de ejecución y mantenimiento, sino para aprovechar sus propiedades, ya que tienen una incidencia directa en lo relacionado con el control de las condiciones ambientales básicas, la regulación de la calidad del aire interior y por ende, en la salud de los usuarios. Dicha labor puede iniciar en la etapa formativa de los profesionales de la construcción, con la intención de normalizar el estudio o correcta selección de los sistemas constructivos en función del clima, pero también identificando la función de cada espacio; para garantizar así, que las propuestas de diseño responderán -satisfactoriamente- a los requerimientos de regulación de la humedad, mediante su absorción, transpiración y/o evaporación.

The level of indoor air quality (IAQ) has a direct incidence on the human health, therefore, is the object of study of bioclimatic design, since it promotes the harnessing environmental factors for the creation and conditioning of spaces in which users experience comfort and well-being. In addition, to encourage construction with common sense, where the rational use of resources and low energy dependence prevail. In this thesis it has been identified the properties of the materials that make up the most common wall coverings (hydrated lime, cement, cement mortar and gypsum) for recognizing those that best adapt to the weather in Mexico City, as it could be verified, they contribute to the control of some risk factors (physical:moisture, chemical:toxics and biological:microbes) related with a low indoor air quality at dwellings. This function mitigates or reduces the appearance of some of the most frequent respiratory ailments in users such as: allergies, asthma, rhinitis, flu and sinusitis. The analyses to which the coatings of four binding materials were subjected, allowed to evaluate their performance in the face of semi-controlled environmental factors (temperature, relative humidity, and carbon dioxide concentration) inherent to the operation of the interior space itself and the place of its location. Obviously, all the coatings reacted differently and according with the physical and chemical properties of the materials in each of them. Being the most representative and satisfactory variations, those related to the permeability and biocidal effect of coatings made with hydrated lime mixture. The pathologies that some coatings showed throughout the monitoring period, due to insufficient moisture management, the high microbial development, and the chemical nature of the binding material, were cryptoefflorescences, mold, bacteria and particle shedding/dissemination; they were defining to establish that in similar way to living beings, building materials need specific hygrothermal ranges, to let them works in an optimal state. According with the above, it is considered convenient to raise awareness among the population on issues as important for social welfare, such as the selection of materials and -consequently- conservation of wall coverings, not only to reduce the costs of execution and maintenance, but to take advantage of their properties, since they have a direct incidence in all related with the control of basic environmental conditions, the regulation of indoor air quality and therefore, in users’ health. This work can begin in the formative stage of construction professionals, with the intention of standardizing the study or correct selection of construction systems depending on the weather, but also identifying the function of each space; to guarantee that the design proposals will respond -satisfactorily- to the requirements of humidity regulation, through its absorption, transpiration and/or evaporation.

Muro, recubrimientos, patologías, salud. Wall, coating, pathologies, health. Indoor air pollution--Health aspects. Architecture--Health aspects. Interior walls. Protective coatings. Lime as a disinfectant. Building materials. Communicable diseases--Transmission--Prevention. Contaminación del aire interior. Muros interiores. Revestimientos. Cal como desinfectante. RA577.5 HUMANIDADES Y CIENCIAS DE LA CONDUCTA CIENCIAS DE LAS ARTES Y LAS LETRAS ARQUITECTURA DISEÑO ARQUITECTÓNICO

Thermal and mechanical properties of PLA-based multiscale cellulosic biocomposites

MIGUEL ANGEL RUZ CRUZ Pedro Jesús Herrera Franco Emmanuel Alejandro Flores Johnson MARIA VERONICA MORENO CHULIM LUCIANO MIGUEL GALERA MANZANO Alex Valadez González (2022, [Artículo])

In this work polylactic acid (PLA) based multiscale cellulosic biocomposites were prepared with the aim to evaluate the effect of the incorporation of cellulose nanocrystals (CNCs) on the PLA biocomposites reinforced with cellulose microfibers (MFCs). For this, PLA composite materials reinforced with both MFCs and with a combination of MFCs and CNCs were prepared, while keeping the content of cellulosic reinforcements constant. The thermal and mechanical properties of these multiscale PLA biocomposites were characterized by thermogravimetry (TGA), differential scanning calorimetry (DSC), flexural mechanical and, dynamic mechanical (DMA) tests. Likewise, they were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results show that the replacement of MFCs by CNCs in the 1–5% range appreciably modifies the thermal and mechanical properties of multiscale compounds. For example, they increase the thermal stability of the materials, modify the PLA crystallization process and play the role of adhesion promoters since the mechanical properties in flexure increase in the order of 40% and the storage modulus increases in the order of 35% at room temperature. Also, the addition of CNCs increases the relaxation temperature of the material from 50 to 60 °C, thereby expanding the temperature range for its use. © 2022 The Author(s)

MULTISCALE BIOCOMPOSITES CELLULOSE MICROFIBER CELLULOSE NANOCRYSTALS HIERARCHICAL STRUCTURE PROPERTIES INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS TECNOLOGÍA DE MATERIALES PROPIEDADES DE LOS MATERIALES PROPIEDADES DE LOS MATERIALES