Mesoporous iron oxides with tailored structural and magnetic properties were synthesized using the SBA-15 silica template and two different iron precursors: Fe(NO3)(3)& sdot;9H(2)O and Fe(C5H(7)O(2))(3), denoted as FeM-1 and FeM-2, respectively. The synthesis involved a two-step impregnation-calcination process followed by silica removal. Comprehensive characterization was performed using techniques such as nitrogen adsorption-desorption isotherms, TEM, SEM-EDX, XRD, XPS, and Mossbauer spectroscopy, as well as magnetic measurements. The results revealed significant differences in structural and magnetic properties between the two samples. FeM-1 exhibited higher structural order, greater homogeneity, and a single-phase alpha-Fe2O3 composition, whereas FeM-2 showed a bimodal pore size distribution and a dual-phase composition of alpha-Fe2O3 and gamma-Fe2O3. Magnetic characterization indicated enhanced magnetization in FeM-2 due to the ferrimagnetic nature of gamma-Fe2O3, while FeM-1 displayed lower magnetization consistent with the weak ferromagnetic behavior of alpha-Fe2O3. The combination of structural and magnetic analyses demonstrated the critical role of precursor selection in tuning the material properties for potential applications in catalysis and magnetic devices.

En este trabajo se presentan los avances alcanzados en la síntesis y caracterización de nanoestructuras basadas en óxidos de hierro mesoporosos y sus cuplas con Ni y Co, las cuales son diseñadas con el objetivo de conferirles fotoactividad bajo radiación UVA-Vis. Se prevé que en estas condiciones los sólidos den lugar a la generación de radicales oxidantes en medio acuoso capaces de degradar contaminantes orgánicos recalcitrantes. Además, se espera desarrollar propiedades magnéticas adecuadas para facilitar la recuperación y reutilización de los materiales. El método de síntesis seleccionado es el de moldeado duro (hard-templating) que consiste en usar una matriz mesoporosa del tipo de la SBA-15 como molde para la formación de la estructura mesoporosa. De esta manera, luego de eliminar selectivamente la matriz se obtiene un sólido que es una réplica inversa del material utilizado como molde. Las propiedades estructurales y ópticas de los óxidos obtenidos se midieron por medio de sortometría, difracción de rayos X (DRX) y UV-Vis DR. Las propiedades magnéticas se midieron con magnetometría de muestra vibrante (VSM).

The surplus of glycerol generated as a by-product in biodiesel production increased interest in the investigation of the catalytic conversion of this platform molecule into valuable chemical products, such as glycerol carbonate. Therefore, the catalytic transesterification of glycerol and dimethyl carbonate for the synthesis of glycerol carbonate was studied using Cu-Zn-Mg-Al mixed oxide catalysts with different Cu-Zn atomic ratios. Layered double hydroxides were the precursors materials to obtain multi metallic oxides. They were synthesized by coprecipitation. The materials were physico-chemically characterized by XRD, MP-AES, N2 sorption, SEM, XPS and TPDCO2. The addition of Cu and Zn to the Mg and Al matrix improved the catalytic behaviour of the solid materials. First, the highest glycerol carbonate yield was reached with the catalyst with the highest Zn load at 70 degrees C for 90 min. This result was taken as a basis to modify parameters and find the optimal reaction conditions. They were a temperature of 85 degrees C, a reaction time of 270 min, a DMC:glycerol molar ratio of 2:1, solvent free and 7.5 wt% of catalyst. The highest yield obtained (82%) was attributable to the synergistic effect of the Cu-Zn load promoted by an adequate distribution of basicity and textural properties. The reuses of the best catalyst were also investigated.

A new magnetic layered double hydroxide (MLDH) composed of Fe, Mg, and Al was designed to improve gallic acid delivery to breast tumors. The metals formed the octahedrons within the layers, while the gallate ions were dissolved in the aqueous interlayer space. The drug loading was 30 %, determined with UV/Vis spectrophotometry. The material exhibited superparamagnetic behavior with a saturated magnetization of 5.5 emu/gr. This magnetic property enables the compound to be directed towards the therapeutic target using an external magnetic field, while the superparamagnetic attribute prevents the material from remaining magnetized in the body after the external magnetic field is removed. The diameter of the composites, measured from TEM images, was 110 nm: small enough for systemic circulation. For comparison, a conventional layered double hydroxide composed of Mg and Al was loaded with gallic acid and impregnated with Fe3O4 magnetic nanoparticles (LDH-NP). The drug loading was slightly lower (23 %), and the material demonstrated a combination of superparamagnetic and ferromagnetic behavior. However, the saturated magnetization was higher, 15 emu/gr for the superparamagnetic-like component and 13 emu/gr for the ferromagnetic-like component. From TEM images, the diameter of the composites was 57 nm. Drug release was studied with Franz diffusion cells. Both systems showed fast release at the lysosomal pH (4.8), but the MLDH avoids the release at the blood pH (7.4) more than the LDH-NP. Lastly, the systems were tested against breast cancer cells. After 48 h, the new composite demonstrated a 77 % reduction in cell viability, while the conventional composite impregnated with NPs showed a 66 % reduction. The designed Fe/Mg/Al magnetic nano composite loaded with gallic acid is easier to manufacture and holds promise for breast cancer treatments.

Current cancer chemotherapy is associated with many side effects and, in some cases, drug resistance, which makes the search for new active molecules and drug delivery strategies imperative. Carbamazepine is an antiepileptic compound that has shown efficacy against breast cancer cell lines. In this study, it was incorporated into layered double hydroxide nanoclays, the percentage of drug loading was increased compared to previous research, and the clays were impregnated with magnetic Fe3O4 nanoparticles. The goal of the magnetic Fe3O4-impregnation was to direct the nanocomposites to the therapeutic target with an external magnetic field. The nanoclay-carbamazepine composites had a carbamazepine loading of 51 %, and the nanoclay-carbamazepine-nanoparticles had a drug loading of 13 % due to the addition of more ingredients. The structure of the composites was analyzed by X-ray diffraction and Scherrer equation, showing a layered double hydroxide organization with crystal sizes of 9-15 nm; from transmission electron microscopy, the final compounds showed a particle size of 97-158 nm, small enough for systemic circulation. In vibrating sample magnetization studies, the composites showed a superparamagnetic behavior with high magnetic saturation (9-17 emu/gr), which should allow a good material attraction by an external magnetic field located near the tumor. In vitro drug release studies were done in Franz cells and measured by UV/Vis spectrophotometry; they showed that carbamazepine release from the nanocomposites responds to the media pH: a good drug release at the lysosome pH and slow release at the blood pH. Finally, the efficacy was tested in vitro in MDA-MB-231 breast cancer cells, and the composites showed an enhanced efficacy in comparison with that produced by the free drug (96 % and 62 % of cell inhibition respectively). Carbamazepine administered with magnetic clays as a carrier is a promising treatment for breast cancer, and further studies should be done to measure the arrival time and the efficacy in vivo.

Temperature- and doping-dependent thermoelectric behavior of p-type SnS, and their dependence on space-group symmetry (Pnma(62)-SnS and C2mb(39)-SnS), were investigated by density functional theory calculation combined with the Boltzmann transport theory. Our results show that the anisotropy in electrical conductivity of C2mb-SnS (Pnma-SnS) in its in-plane value is six orders (one order) of magnitude greater than its corresponding out-of-plane value. The thermopower in C2mb-SnS is about eight times as large as that of in Pnma-SnS at high temperatures, and the maximum Power Factor for C2mb-SnS is two times as large as that of Pnma-SnS, being this difference considerably greater at high temperatures. Our findings indicate that the role of effective masses and bandgap characteristics are critical in reducing the impact of the bipolar transport effect at high temperatures, contributing to our predicted better performance of the C2mb-SnS as a thermoelectric device compared to Pnma-SnS.

Temperature and doping dependence of the power factor of p-type SnS, and their dependence on space-group symmetry (Pnma(62)-SnS and C2mb(39)-SnS), were investigated by density functional theory calculation combined with the Boltzmann transport theory. Our results show that the anisotropy in electrical conductivity of C2mb-SnS (Pnma-SnS) in its in-plane value is six orders (one order) of magnitude greater than its corresponding out-of-plane value. The thermopower in C2mb-SnS is about eight times as large as that of in Pnma-SnS at high temperatures, and the maximum Power Factor for C2mb-SnS is two times as large as that of Pnma-SnS, being this difference considerably greater at high temperatures. Our findings indicate that the role of effective masses and bandgap characteristics are critical in reducing the impact of the bipolar transport effect at high temperatures, contributing to our predicted better performance of the C2mb-SnS as a thermoelectric device compared to Pnma-SnS.

We report the successful growth of BaFe12O19–BaTiO3 (BaM-BTO) bilayer thin films using pulsed laser deposition, considering different crystallographic textures; BTO on (0001)-BaM and BaM on (100)-BTO. Our study involved the bilayers, the individual ferrite and titanate films, and the targets used in their growth. Raman spectroscopy and X-Ray diffraction were used to examine the structure of BaM-BTO thin films, indicating that there is no formation of impurity phases. The morphological characterization was made by scanning electron microscopy, and the magnetic behaviour was studied using SQUID magnetometry. The spontaneous magnetization, magnetic anisotropy constant, and anisotropy field were determined simultaneously from the magnetic hysteresis loop. In addition, we also studied the influence of different annealing temperatures over the magnetic behaviour of bare BaM and covered with BTO thin film. This allows to discern between the different magnetization reversal processes in bilayer systems, indicating a strong correlation between the anisotropy field and the coercive field, and an unusual linear relation of the anisotropy constant with the spontaneous magnetization. Our results indicate a direct influence of the BTO on the magnetic properties of the BaM phase, which places these composite bilayers as excellent candidates for the development of multifunctional devices.

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Magnetic nanoparticles have been synthesized on mesoporous silica by a simple method without the need for either an alkali or an organic solvent, nor for rigorous pH control, making it a safe procedure for the nanomedicine field. The systems have been exhaustively characterized through different instrumental techniques, including the analysis of physicochemical properties by N2 adsorption, TEM, HAADF/STEM, SAED, EDS, XRD, XPS, and UV/Vis DRS. Magnetic properties have been tested by means of magnetization curves at room temperature and 5 K, ZFC-FC curves, and Mössbauer spectroscopy. The nanocomposite obtained by heating in N2 atmosphere showed good specific surface area and structural order, as well as high magnetization and negligible magnetic hysteresis and remanence, arising from the presence of finely dispersed magnetite nanospecies. These features are very relevant for future application as carriers for drug delivery systems, among other uses.

Fil: Carraro, Paola Maria. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Centro de Investigacion y Tecnologia Quimica. Universidad Tecnologica Nacional. Facultad Regional Cordoba. Centro de Investigacion y Tecnologia Quimica; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto de Fisica Enrique Gaviola. Universidad Nacional de Cordoba. Instituto de Fisica Enrique Gaviola; Argentina

Fil: Carraro, Paola Maria. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Centro de Investigacion y Tecnologia Quimica. Universidad Tecnologica Nacional. Facultad Regional Cordoba. Centro de Investigacion y Tecnologia Quimica; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto de Fisica Enrique Gaviola. Universidad Nacional de Cordoba. Instituto de Fisica Enrique Gaviola; Argentina

Pure siliceous and aluminosilicate mesoporous molecular sieves of MCM-41 type have been used as support for nickel incorporation (2.5 wt%) by wet impregnation method. The hydrogen adsorption capacities at 77 K of these materials have been studied. Various techniques such as X-ray diffraction, N2 adsorption–desorption, X-ray photoelectron spectroscopy, Temperature-Programmed Reduction, UV–Vis diffuse reflectance spectroscopy and adsorption of pyridine coupled to infrared spectroscopy were employed to characterize the materials. In addition, Density Functional Theory calculations were used in order to interpret the results of hydrogen adsorption. The results obtained show that isolated metallic species are capable to promote hydrogen favorable sites. Isolated mononuclear Ni2+ species on the surface strengthen the interaction with the H2, enhancing the hydrogen adsorption capacity.

Los hidróxidos de doble capa son materiales pertenecientes a las arcillas aniónicas. Dichas arcillas pueden ser modificadas con determinados metales de manera de impartirles carácter básico para ser utilizadas en reacciones de química fina. En este trabajo se presenta el estudio realizado a los hidróxidos de doble capa incorporados por el método de coprecipitación, con metales como el Zn, Ni, La y Ce. Dichos materiales presentaron buena estructura, área superficial y alta basicidad. En cuanto a la actividad catalítica, se estudió la reacción de condensación para la obtención de chalconas, obteniéndose conversiones por encima de 80% con altas selectividades y pureza del producto deseado.

Mesoporous silica material type MCM-41 was modified with different amounts of Zn (1 - 15 wt.%) by the wet impregnation method. Support and catalysts were characterized by means of powder X-ray diffraction (XRD), N-2 nitrogen adsorption desorption, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and ICP-OES techniques. The Zn-modified mesoporous silicates have been successfully tested for the degradation in aqueous solutions of different endocrine disrupting (EDs), such as herbicides (atrazine), compounds derived from the plastic industry (bisphenol A) and from the pharmaceutical industry (clofibric acid). The results showed that the Zn/M(5) catalyst exhibited the highest activity. The high performance of this material indicates that the heterogeneous photo-Fenton-like reaction appears as a very promising pretreatment capable of enhancing the biodegradability of water contaminated with biorecalcitrant chemicals, as the most endocrine disruptors.

The hydrogen adsorption capacity of mesoporous materials MCM-41 modified with Co, Fe, Ti, Mg and Ni at 77 K and 10 bar was investigated. Various techniques including XRD, N-2 adsorption and DRUV-vis were employed for the materials characterization. The results showed that a low nickel loading on MCM-41 support promoted the presence of hydrogen-favorable sites, increasing the hydrogen storage capacity. (C) 2018 Elsevier B.V. All rights reserved.

The SAM-CONAMET congress is one of the largest Ibero-American conferences on research, technology and applications of Materials Science. The same is done alternately in Argentina and Chile, called CONAMET-SAM when it is developed in Chile. Its origin goes back to the year 2001 when the annual meetings that the Argentinean Association of Materials (SAM) and the Chilean Society of Metallurgy and Materials (SOCHIM) were carrying out independently. It aims to bring together the Material Science community to establish contacts, improve integration and present and discuss critically the latest developments and innovations in this area. It constitutes, therefore, an update on the latest research on new materials, allowing to know the current situation of the research that is developed in the field, following the SAM foundational spirit [1].

In this study, ordered mesoporous carbons CMK-3 were prepared by a nanocasting method using SBA-15 silica as template and sucrose as carbon source. The pure CMK-3 was modified with nickel by wet impregnation method and the effects on hydrogen storage capacity were studied at different pressures and temperatures. The structural, textural and chemical properties were evaluated in order to investigate their correlation with hydrogen adsorption properties. Also, computational methods (DFT) contributed to the understanding of hydrogen storage interactions in the Ni/C samples. Two different behaviors on the hydrogen adsorption were obtained after reduction treatment under H-2 atmosphere. For the unreduced samples at 77 K, the textural properties were the determining factor in the H-2 storage capacity. On the other hand, for the reduced samples at room temperatures, the presence of nickel nanoparticles increased the hydrogen adsorption, with a possible dependence of the particle size.

El hidrógeno es un importante vector energético capaz de sustituir el uso de combustibles fósiles en la actualidad. Uno de los principales inconvenientes para la implementación de sistemas que emplean hidrógeno es su almacenamiento. Actualmente, existen investigaciones en curso con el fin de desarrollar materiales para ser empleados en sistemas de almacenamiento, como por ejemplo materiales formadores de hidruros y materiales porosos que almacenan hidrógeno por adsorción. En este trabajo se sintetizaron materiales MCM-41 por síntesis hidrotérmica con relación Si/Ni = 20 y 60 y tiempos de síntesis de 0 a 7 días. Se estudió la influencia del tiempo de síntesis en las propiedades estructurales y texturales de los materiales, y se evaluó la adsorción de hidrógeno y el efecto de incorporar níquel en su estructura para mejorar el almacenamiento. Los materiales fueron caracterizados mediante adsorción-desorción de N2 a 77 K, difracción de rayos X, microscopía electrónica de transmisión y espectroscopia ultravioleta visible con reflectancia difusa.