El cine mexicano de la edad de oro y su impacto internacional

A partir de una investigación documental en publicaciones periódicas de Argentina, Colombia, Cuba, Chile, Estados Unidos, Honduras, México, Nicaragua y Venezuela, este artículo demuestra el interés que el cine mexicano producido entre 1936 y 1956 provocó en los espectadores de Hispanoamérica y Estados Unidos, al igual que la presencia de actores, cineastas, temas y personajes de otros países hispanohablantes en la industria cinematográfica mexicana durante la denominada edad de oro del cine mexicano. Se constató la influencia de este cine en la conformación de la identidad cultural de los mexicanos y su proyección internacional

Virginia Aguirre una cuenta pendiente

Ensayo memorialístico que oborda la labor de Virginia Aguirre  como editora de la revista La Colmena  y, principalmente, como promotora cultural

"La llave" una perversidad cinematográfica de Josefina Vicens

_En el presente trabajo se da cuenta de la labor que desempeñó Josefina Vicens en la industria cinematográfica, a la par de su labor como escritora. En este medio se desempeñó durante un largo periodo en el que intervino en diversas producciones

Clinkering and hydration study of non-active and active Belite-Alite-Ye'elimite (BAY) cements

The aim of AIM is to promote industry-driven, interdisciplinary research in material science and engineering in order to provide leading-edge, sustainable solutions to the challenges facing engineers in today’s changing society and environment. http://www.ucl.ac.uk/aim/conference-info/37ccsThe manufacturing process of ye'elimite rich cements emit about 15-37% less CO2 to the atmosphere than OPC. Cements that contain belite, ye’elimite and ferrite, known as BYF cements, are promising eco-friendly binders. However, belite, their main phase, shows a slow hydrating behaviour; therefore the corresponding mortars present lower mechanical strengths than OPC at early ages. To solve this problem, BYF clinkers can be activated by: i) forming alite jointly with belite and ye’elimite during clinkering, known as BAY clinkers. The alite and ye’elimite reaction with water should develop high mechanical strengths at early ages, besides, belite contributes to later curing times. ii) A second activation is based on the stabilisation of alpha forms of belite by dopants. The objective of this work is to obtain two types of BAY clinkers (standard and active BAY) using CaF2 as mineraliser and borax as dopant agent to stabilize alpha forms of belite phase. After that, anhydrite was added as sulphate source to obtain the corresponding cements. The hydration behaviour of these cements has been studied through rheological and x-ray diffraction measurements, the latter combined with Rietveld quantitative phase analysis. In addition, mechanical and dimensional properties of BAY mortars are also presented and discussed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Advanced synchrotron studies of ye'elimite-based cement pastes

Synchrotron characterization techniques [1] are being used to study Portland-based cements and recently also CSA and related cements. A key property of these techniques is that they do not require sample preparation, so the microstructures of the pastes can be preserved. The classical application of synchrotron tools is powder diffraction used to determine the crystalline phase content evolution with hydration including the overall amorphous fraction. Furthermore, other most advanced techniques are being applied to ye'elimite-containing pastes such as i) Total Scattering Synchrotron Powder Diffraction (TS-SXPD), and ii) Ptychographic Synchrotron X-ray Computed Tomography (PSXCT). All these applications will be reviewed here. TS-SXPD data coupled with the Pair Distribution Function (PDF) analysis methodology [2] allows having a better insight about the nanocrystalline/amorphous atomic arrangements in the gels. It has been very recently shown that nanogibbsite with very small particles, 3nm, is the main constituent of ye'elimite-gypsum hydration paste [2]. Nanogibbsite particles being smaller than those originated from the hydration of monocalcium aluminate. In addition, PSXCT is a tomographic technique that profits from the partly coherent nature of the synchrotron beam to provide better (smaller) resolution, which can be lower than 100 nm. It also provides the mass densities if the chemical stoichiometries are known. This technique has been applied to ye'elimite hydration to determine the microstructure and chiefly the bulk densities of nanogibbsite [3]. The microstructure evolution at early age was also followed [4]. Figure 1 shows an example of a slide of the electron density tomogram for a ye'elimite paste at 8 days of hydration and the corresponding histogram for the full volume with all phases identified.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.This work has been supported by Spanish MINECO through BIA2014-57658-C2 and BIA2017-82391-R, which are co-funded by FEDER

Applications of synchrotron x-ray powder diffraction in hydrated cements: high-resolution and high-pressure studies

The main aim of this study is to apply synchrotron radiation techniques for the study of hydrated cement pastes. In particular, the tetracalcium aluminoferrite phase, C4AF in cement nomenclature, is the major iron-containing phase in Ordinary Portland Cement (OPC) and in iron rich belite calcium sulfoaluminate cements. In a first study, the hydration mechanism of pure tetracalcium aluminoferrite phase with water-to-solid ratio of 1.0 has been investigated by HR-SXRPD (high resolution synchrotron X-ray powder diffraction). C4AF in the presence of water hydrates to form mainly an iron-containing hydrogarnet-type (katoite) phase, C3A0.84F0.16H6, as single crystalline phase. Its crystal structure and stoichiometry were determined by the Rietveld method and the final disagreement factors were RWP=8.1% and RF=4.8% [1]. As the iron content in the product is lower than that in C4AF, it is assumed that part of the iron also goes to an amorphous iron rich gel, like the hydrated alumina-type gel, as hydration proceeds. Further results from the high-resolution study will be discussed. In a second study, the behavior of pure and iron-containing katoites (C3AH6 and C3A0.84F0.16H6) under pressure have been analyzed by SXRPD using a diamond anvil cell (DAC) and then their bulk moduli were determined. The role of the pressure transmitting medium (PTM) has also been studied. In this case, silicone oil as well as methanol/ethanol mixtures have been used as PTM. Some “new peaks” were detected in the pattern for C3A0.84F0.16H6 as pressure increases, when using ethanol/methanol as PTM. These new peaks were still present at ambient pressure after releasing the applied pressure. They may correspond to crystalline nordstrandite or doyleite from the crystallization of amorphous aluminium hydroxide. The results from the high-pressure study will also be discussed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Acknowledgments: We thank CELLS-ALBA (Barcelona, Spain) for providing synchrotron beam time. We also thank the financial support by BIA2014-57658-C2-1-R and BIA2014-57658-C2-2-R (FEDER)

A Careful Design for a Tool to Detect Child Pornography in P2P Networks

This paper addresses the social problem of child pornography on peer-to-peer (P2P) networks on the Internet and presents an automated system with effective computer and telematic tools for seeking out and identifying data exchanges with pedophilic content on the Internet. The paper analyzes the social and legal context in which the system must operate and describes the processes by which the system respects the rights of the persons investigated and prevents these tools from being used to establish processes of surveillance and attacks on the privacy of Internet users

Design and optimisation of new formulations of Belite-Alite Calcium Sulfoaluminate (BACSA) eco-cements

Belite Calcium SulfoAluminate (BCSA) eco-cements were developed as OPC substitutes since in their production release 22% less CO2 than OPC. BCSA eco-cements contain belite as main phase (>50 wt%) and ye'elimite as secondary main phase (~30 wt%). However, these materials develop low mechanical strengths at intermediate hydration ages (3, 7 and 28 days). A solution to this problem may involve the design and preparation of clinker/cement with the highest percentage of coexisting alite and ye'elimite. These materials are known as Belite-Alite Calcium SulfoAluminate (BACSA) clinkers/cements. Their manufacture may produce 15% less CO2 than OPC. Alite is the main component of OPC and is responsible for early mechanical strengths. The reaction of alite and ye´elimite with water will develop cements with high mechanical strengths at early ages, while belite will contribute to later curing times. This work is focused on the design and optimisation of all the parameters evolved in the preparation of BACSA eco-clinkers that develop mechanical strengths comparable to those of OPC with a reduction in CO2 emissions of at least 15% when compared to OPC production. These parameters include the selection of the raw materials (lime, gypsum, kaolin and sand), milling conditions of the crude, clinkering temperature (from 1280 to 1300ºC) and holding time at every temperature, and final composition. The clinker with the targeted composition (belite ~ 60 wt%, alite ~ 13 wt% and ye'elimite ~ 10 wt%) was chosen to perform the scaling-up (2 kg). BACSA eco-clinkers were chemically and mineralogically characterised through X-ray fluorescence and laboratory X-ray powder diffraction (LXRPD), the latter in combination with the Rietveld methodology to obtain the full phase assemblage including Amorphous and Crystalline non-quantified, ACn, contents. Finally, the hydration of the selected BACSA cement paste (prepared with the scaled-up clinker and anhydrite) was studied mainly through rheological measurements (at very early hydration time) and LXRPD in combination with the Rietveld methodology and G-factor method. The compressive strengths were also measured at different hydration times and were compared with OPC.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.Societ

Rheological and hydration characterization of calcium sulfoaluminate cement pastes

Calcium sulfoaluminate (CSA) cements are currently receiving a lot of attention because their manufacture produces less CO2 than ordinary Portland cement (OPC). However, it is essential to understand all parameters which may affect the hydration processes. This work deals with the study of the effect of several parameters, such as superplasticizer (SP), gypsum contents (10, 20 and 30 wt%) and w/c ratio (0.4 and 0.5), on the properties of CSA pastes during early hydration. This characterization has been performed through rheological studies, Rietveld quantitative phase analysis of measured x-ray diffraction patterns, thermal analysis and mercury porosimetry for pastes, and by compressive strength measurements for mortars. The effect of the used SP on the rheological properties has been established. Its addition makes little difference to the amount of ettringite formed but strongly decreases the large pore fraction in the pastes. Furthermore, the SP role on compressive strength is variable, as it increases the values for mortars containing 30 wt% gypsum but decreases the strengths for mortars containing 10 wt% gypsum.This work has been supported by Spanish Ministry of Science and Innovation through MAT2010- 16213 research grant, which is co-funded by FEDER, and Ramón y Cajal Fellowship (RYC-2008- 03523)

Hydration studies of calcium sulfoaluminate cements blended with fly ash

The main objective of this work is to study the hydration and properties of calciumsulfoaluminate cement pastes blended with fly ash (FA) and the corresponding mortars at different hydration ages. Laboratory X-ray powder diffraction, rheological studies, thermal analysis, porosimetry and compressive strength measurements were performed. The analysis of the diffraction data by Rietveld method allowed quantifying crystalline phases and overall amorphous contents. The studied parameters were: i) FA content, 0, 15 and 30 wt.%; and ii) water addition, water-to-CSA mass ratio (w/CSA = 0.50 and 0.65), and water-to-binder mass ratio (w/b = 0.50). Finally, compressive strengths after 6 months of 0 and 15 wt.% FA [w/CSA = 0.50] mortars were similar: 73 ± 2 and 72 ± 3 MPa, respectively. This is justified by the filler effect of the FA as no strong evidences of reactivity of FA with CSA were observed. These results support the partial substitution of CSA cements with FA with the economic and environmental benefitsThis work has been supported by Spanish MINECO through MAT2010-16213 research grant, which is co-funded by FEDER. I. Santacruz thanks a Ramón y Cajal fellowship, RYC-2008-03523