Suchergebnisse

Al momento de que México obtiene su independencia respecto a España en 1821, se comienza un proceso político-económico para su consolidación como Estado nacional. En ese devenir se inscriben políticas del nuevo Estado mexicano que trataron de incentivar la migración de extranjeros. Esto, con el fin de poblar, desarrollar e impulsar las actividades económicas y sociales de la joven nación americana. Para aclarar mejor esta etapa de construcción nacional, analizaremos las relaciones entre México y Europa, en cuestiones políticas y económicas, pues se remontan al entramado proceso comercial entre la Nueva España y los diversos reinos europeos mediados por la metrópoli española. Agregando la importancia económica del territorio americano, pues fue sustancial para el desarrollo español, "se puede decir que el auge minero del siglo XVIII en el virreinato le da el carácter de metrópoli económica, comercial y financiera que las otras posesiones españolas en América no tienen."1 La migración hacia México se inscribe en un proceso por etapas, pues es el caso de grupos atraídos por antecedentes históricos, a partir de las publicaciones de Alexander von Humboldt sobre las riquezas de la Nueva España en la primera década del siglo XIX, o en el caso de la actividad minera ya desde finales del siglo XVIII con las reformas en el sector. La búsqueda de especialistas extranjeros fue un factor que expuso la situación de las minas y sus beneficios al exterior, en específico en Europa. En ese sentido se dieron contrataciones por parte del reino español a técnicos de otras zonas como Alemania. Las obras de Humboldt no fueron las únicas, pues tras su ensayo sobre Nueva España le siguieron diversas publicaciones que fueron difundidas en un amplio sector europeo y estadounidense, tal es el caso del británico George Ward con su texto Mexico in 1827, y ya para la tercera década del siglo XIX tuvieron difusión diversos textos sobre investigaciones realizadas en México, por ejemplo mencionaremos sólo a Joseph Burkart2, Aufenhalt und Reisen in Mexico in den Jahren 18a México, además de las rutas mineras e industrias del ramo, además, hace una descripción sustanciosa de Zacatecas desde 1828 a 1834. Al hacer mención de dichas obras es con el fin de mostrar que la difusión de México en Europa no fue llevada a cabo exclusivamente por Humboldt, además, ya desde el primer tercio del siglo XIX se puede percibir producción de estudios sobre regiones específicas, que fueron difundidas en Alemania e Inglaterra principalmente, son los casos de Burkart y Ward. Ese devenir de presencia extranjera para el beneficio de las minas a finales del siglo XVIII se estableció en lugares y regiones específicas, tal es el caso de Real del Monte y las minas de Zacatecas, sitios que fueron analizados por dichos técnicos sajones para implementar técnicas de vanguardia como el método de barril o como se le conocía en Europa, el método de Born. Tales incursiones extranjeras patrocinadas por la Corona española, tuvieron alcances hasta la consolidación de centros especializados cono el Real Seminario de Minería, y aún más, hasta la consolidación del Estado nacional mexicano. Para el caso zacatecano la recepción de extranjeros europeos, en específico alemanes, fue en el tenor de la actividad minera para el primer tercio del siglo XIX. Esta migración se podría denominar como un pequeño grupo, se conformó por las sociabilidades de estos respecto a sus actividades. Los espacios donde incursionaron -por lo menos entre 1825 y 1835- fueron en el minero, militar y artístico-arquitectónico, pero tras las circunstancias políticas de Zacatecas, además de la culminación de las actividades de algunos de ellos, desde 1834 a 1836, el grupo se retiró del territorio zacatecano.25 bis 1834, en donde describe los pormenores de su viaje

Understanding this moment of the Spanish transition period within the Church, as a catalyst for a prepared change, makes us look to the Second Vatican Council II - the Dignitatis humanae declaration - where the Catholic Church passed from the confessional state, as Model, to the proclamation of religious freedom. Propitiated by this council and by figures such as those of Cardinal Tarancón who was not worried about the non-denominational state but of religious freedom, he was part of public liberties. The Church played an important role in this path towards democracy, with an outstanding contribution to reconciliation and the restoration of rights and freedoms. According to history, this is a chapter that has not been closed yet, as if the waves of these events continued -becoming less and less- giving reasons for tension, discussion (too heated) and questioning how they were carried out, and how are those actions of the Spanish transition updated. Something makes us intuit that everything is not well done (something very human) and that revisionism is not always made to grow. ; Comprender este momento de la Transiciónen el interior de la Iglesia, como catalizador para un cambio preparado nos hace tener la mirada puesta en el Concilio Vaticano II –en concreto de la declaración Dignitatis humanae–, donde la Iglesia Católica pasó del Estado confesional, como modelo, a la proclamación de la libertad religiosa. Propiciado por este concilio y por figuras como la del Cardenal Tarancón al que no le preocupaba la aconfesionalidad del Estado sino que la libertad religiosa formase parte de las libertades públicas. La Iglesia tuvo un importante papel en este camino hacia la democracia, con una destacada contribución a la reconciliación y la reinstauración de derechos y libertades. La sensación histórica es la de un capítulo aún sin cerrar, dando motivos para la tensión, la discusión (demasiado acalorada) y el cuestionar como se realizaron, y como se actualizan esas actuaciones de la Transición. Algo nos hace intuir que no está bien realizado todo (algo muy humano) y que el revisionismo no siempre es para crecer. ; Compreender este momento de transição dentro da Igreja, como um catalisador para uma mudança preparada, nos faz olhar para o Concílio Vaticano II - especificamente a declaração Dignitatis humanae - onde a Igreja Católica passou do Estado confessional, como um modelo, para a proclamação da liberdade religiosa. Isto foi promovido por este conselho e por figuras como o Cardeal Tarancón, que não estava preocupado com a natureza não confessional do Estado, mas com a liberdade religiosa que faz parte das liberdades públicas. A Igreja desempenhou um papel importante neste caminho rumo à democracia, com uma notável contribuição para a reconciliação e o restabelecimento dos direitos e liberdades. A sensação histórica é a de um capítulo que ainda não foi encerrado, dando origem a tensão, discussão (muito acalorada) e questionamento de como essas ações da transição foram realizadas, e como estão sendo atualizadas. Algo nos faz sentir que nem tudo é bem feito (algo muito humano) e que o revisionismo nem sempre é para o bem do crescimento.

Special Issue: Advanced Microscopy and Spectroscopy for Catalysis . ; Metal-organic frameworks (MOFs) are a family of porous solids combining organic and inorganic moieties with tunable porosity. Their structural parameters have converted MOFs into suitable compounds for gas storage or drug delivery. However, despite the excellent crystallinity they tend to exhibit their analysis through transmission electron microscopy is extraordinarily complicated owing to the high instability under the electron beam irradiation. In here, high-resolution Cs-corrected STEM imaging was used for the observation of the building units of MIL-100(Fe), and special attention was paid to the electron beam current. In addition, MIL-100(Fe) was reacted with AgNO3 through a solid-state reaction technique, which resulted into the formation of metal nanoparticles on the surface. The incorporation of Ag into the porous network has been also investigated. ; AM acknowledges the Government of Aragon and the European Social Fund under the project grant number E/26 "Construyendo Europa desde Aragón" 2014–2020. This work has been partially financed by the Spanish State Research Agency (Agencia Española de Investigación, AEI) and the European Regional Development Fund (Fondo Europeo de Desarrollo Regional, FEDER) through Project MAT2016-77496-R (AEI/FEDER, UE). ; Peer reviewed

One of the pioneering metal organic framework material, called MOF-2 and having the formula [Zn2(BDC)2], still continues awakening interest amongst the scientific community in spite of its layered character. However, the synthesis methods are either experimentally complicated or in two steps through the transformation of MOF-1. Here, we describe the preparation of a high-quality MOF-2 under more sustainable conditions, including room temperature, absence of any amine or any other pH-controller, partial substitution of the harmful organic solvent (N,N-dimethylformamide) by water, and by simply mixing linker and metal sources, the latter being zinc acetate, carefully selected as a function of their solubility in the solvent mixture. The optimum ratio of Zn(OAc)2·4H2O to terephthalic acid (H2BDC) is 1.74 and H2O to DMF is 3. MOF-2 [Zn2(BDC)2] has been characterized using powder X-ray diffraction, thermogravimetric analysis, N2 adsorption/desorption and scanning electron microscopy, all of them supporting the good quality of the material. ; NG acknowledges the financial support from the Spanish Ministry of Foreign Affairs-Spanish Agency for Cooperation and Development through the "Becas Institucionales" Program. ID acknowledges the CSIC for the research leave at Addis Ababa University. The authors acknowledge Spanish Government, MINECO (MAT2012-31127) and the Spanish Research Council CSIC (i-COOP014), for funding. The Chemistry Department, Addis Ababa University is also acknowledged for financial support. ; Peer Reviewed

© 2014 American Chemical Society ; This paper describes the preparation and characterization of nanoscaled M-MOF-74/CPO-27-M (M = Mg, Mn, Co, Ni, and Zn) materials at room temperature. Some of the so-formed crystals are the smallest ones of any metal−organic framework (MOF) material (and, to the best of our knowledge, of any microporous material) ever reported. They are at the limit of being able to diffract, particularly those forming the Co- and Ni-MOF-74 samples. Consequently, unequivocal identification as the crystalline MOF-74 phase was deduced by combining other characterization techniques rather than powder X-ray diffraction. These small crystals are unstable as isolated ones, so they form steady and robust aggregates, whose mechanical properties strongly depend on the crystal size. The particles that result from the "fusion" of nanocrystals smaller than 10 nm (more properly denoted as nanodomains) could not be disaggregated by conventional ultrasonic and graining techniques. On the contrary, agglomerates of crystals larger than 10 nm are dissociable in discrete crystals. It allows characterizing Zn-MOF-74 nanocrystals by advanced electron microscopy methods. Cs-corrected scanning transmission electron microscopy (STEM) provided, for the first time, "quasi" atomic resolution images of MOFs, which are especially unstable under electronic radiation. The magnitude of the crystal size of M-MOF-74 is tentatively associated with the solubility of the metal source. ; Funding is from Spanish Ministry (MAT-2012−31127) and European Union Seventh Framework Programme under Grant Agreement 312483 - ESTEEM2 (Integrated Infrastructure Initiative-I3). ; Peer Reviewed

By using asymmetric di-substituted imidazolium molecules (1-Butyl-3-methylimidazolium (BMIM) and 1-Ethyl-3-methylimidazolium (EMIM) bromide) as the structure directing agents, in combination with simple changes in silica source or sodium/water content it is possible to prepare three pure phase microporous 10-ring siliceous zeolitic structures. The crystallizations are comparatively rapid with fully crystalline material resulting in 1–3 days at 443 K. In contrast to many recipes reported for pure silica materials, the synthesis is performed without the use of HF or without the need to alter the properties of the SDA, while significantly lower amounts of both ionic liquid and mineralizing agent are required. The results obtained indicate that effective phase control can be achieved from a primary gel composition by minor changes to either the silica source or the water/sodium content, with a strong specificity in the formation of topologies with interconnected 10-rings. ; NWO-CW and EPSRC (EP/K007467/1) is thanked for funding support to Andrew M. Beale and Inés Lezcano-González respectively. Manuel Sánchez-Sánchez acknowledges the Spanish Government for financial support (MAT2016-77496-R) and the Slovenian research agency is acknowledged for financial support (grant MR-29397) to Marta Počkaj. ; Peer reviewed

The real industrial establishment of metal–organic frameworks (MOFs) requires significant advances in economic and chemical sustainability. This work describes a novel and simple method to prepare one of the most widely studied MOF materials, i.e., MIL-100(Fe), which significantly improves the sustainability of the conventional process in several aspects. This MOF material is prepared (i) at room temperature (instead of 150 °C used in the conventional method), (ii) after a few hours (instead of 6 days), (iii) in the absence of any inorganic corrosive acid (significant amounts of HF and HNO3 are used in the conventional method), and (iv) it is washed at room temperature (unlike the washing at 80 °C for 3 h). Interestingly, the only difference in the preparation method of MIL-100(Fe) compared with that of semiamorphous Fe-BTC (MOF material commercialized as Basolite F300 having the same metal and linker, and which can be also prepared under similar sustainable conditions) is to start from Fe(II) or Fe(III) sources, respectively, which opens certain versatility options in the room temperature synthesis procedures of MOF materials. The prepared samples were characterized using X-ray diffraction, thermogravimetric analysis, N2 adsorption/desorption isotherms, Cs-aberration corrected scanning transmission electron microscopy, and UV–vis diffuse reflectance spectroscopy. These two room-temperature-made Fe-BTC materials were tested in the industrially demanded photocatalytic degradation of methyl orange under both ultraviolet and solar light radiation. MIL-100(Fe) was a very active photocatalyst in comparison with its homologue. That difference was mainly attributed to the presence of larger cavities within its structure. ; A.M. acknowledges European Union Seventh Framework Programme under Grant Agreement 312483 - ESTEEM2 (Integrated Infrastructure Initiative-I3). C.A.D.C. acknowledges Science without Borders - CNPq - Brazil. K.G. and I.D. also acknowledge CSIC for Development Program I-COOP-2014 COOPB20082 project number. This work has been (partially) financed by the Spanish State Research Agency (Agencia Española de Investigación, AEI) and the European Regional Development Fund (Fondo Europeo de Desarrollo Regional, FEDER) through Project MAT2016-77496-R (AEI/FEDER, UE). ; Peer reviewed

Different TAPO-5 materials, prepared from Ti(III) chloride, have been tested as catalysts in the oxidation of cyclohexene with hydrogen peroxide under anhydrous conditions. Solid TiCl3 was shown to render better synthesis reproducibility and higher catalytic activity of the resultant materials compared to TiCl3 aqueous solution. The synthesis of these materials was carried out under N2 atmosphere to preserve the initial oxidation state of Ti during the crystallization process. As a consequence, the so-called Ti(III)APO-5 materials have Ti environments different to those found in conventional TAPO-5 (Ti(IV)APO-5). Indeed, their catalytic activity in the oxidation of cyclohexene markedly overcomes that of the Ti(IV)APO-5 at any Ti content and after any reaction time. Turnover number (TON) of Ti(III)APO-5 samples exponentially increases as Ti content decreases, the Ti-poorer sample (Ti/(Ti + Al + P) molar ratio of 0.003) reaching TON values higher than 200 after 6 h of reaction at 343 K and higher than 550 after 24 h. The interest of Ti(III)APO-5 catalysts lies on their high selectivity to products formed through allylic oxidation of cyclohexene. The main product of this reaction, 2-cyclohexenyl hydroperoxide, was obtained with more than 80% selectivity over Ti(III)APO-5 catalysts. This behavior is in contrast with the well-known strong tendency of the more active Ti-zeolites to epoxidize the double bond. ; They also acknowledge the Spanish Government for financial support (Projects MAT-2009-13569 and MAT-2012-31127). A. Alfayate acknowledges CSIC for a PhD Jae-Predoc fellowship. ; Peer Reviewed

The use of a metal–organic framework (MOF) as a support for the in situ immobilization of enzymes was explored. The MOF support, a Basolite F300‐like material, was prepared from FeCl3 and the tridentate linker trimesic acid. Immobilization of alcohol dehydrogenase, lipase, and glucose oxidase was performed in situ under mild conditions (aqueous solution, neutral pH, and at room temperature) in a rapid and facile manner with retention of activity for at least 1 week. The catalytic activities of lipase and glucose oxidase were similar to the activities of the free enzymes; with alcohol dehydrogenase, there was a substantial decrease in activity on immobilization that may arise from diffusion limitations. The approach demonstrates that a MOF material, prepared from cheap and commercially available materials, can be successively utilized to prepare stable and catalytically active biocatalysts in a rapid and facile manner. ; Support from the Science Foundation Ireland (12/RC/2275), the Programme for Third Level Institutions, the Irish Research Council (postdoctoral fellowship to V.G. GOIPD/2015/287), and the Spanish Government (MAT‐2012‐31127) is gratefully acknowledged. This work was also partially financed by the Spanish State Research Agency (Agencia Española de Investigación, AEI) and the European Regional Development Fund (Fondo Europeo de Desarrollo Regional, FEDER) through the Project MAT2016‐77496‐R (AEI/FEDER, UE). ; Peer reviewed