Kinetics of crystallization of FeB-based amorphous alloys studied by neutron thermo-diffractometry

Kinetics of crystallization of two amorphous alloys, Fe70Cr10B20 and Fe80Zr10B10, have been followed up by neutron thermodiffractometry experiments performed in the two axis diffractometer D20 (ILL, Grenoble). The structural changes are directly correlated with the temperature dependence of the magnetization. Fe70Cr10B20 crystallizes following a two-step process: an eutectic crystallization of alfa-Fe (bcc) and the metastable tetragonal phase (Fe0.8Cr0.2)3B followed by another eutectic transformation to the stable phase (Fe0.75Cr0.25)2B and more segregation of alfa-Fe. These tetragonal phases are magnetically anisotropic, giving rise to a large increase of the coercivity. This behaviour is similar to that of Fe80B20 alloys, with Cr atoms replacing the Fe positions in both crystalline phases. Fe80Zr10B10 shows also a two-step process in which two polymorphic transformations take place.Comment: 3 pages. Proceedings International Workshop Non-Crystalline Solids 2006, Gijon (Spain

Life cycle assessment of hot mix asphalt with recycled concrete aggregates for road pavements construction

In this study a comparative life cycle assessment (LCA) was conducted according to a ‘cradle-to-laid’ approach to evaluate the potential environmental impacts related to the use of recycled concrete aggregates (RCAs) as a partial replacement of coarse natural aggregates in the production of Hot Mix Asphalt (HMA). Specifically, three percentages of RCA replacements were analyzed: 15, 30 and 45%. Primary data collected mainly through surveys performed in Colombian contractors from the region of Barranquila were used to model the foreground system. The SimaPro 8.4.0 software was used for modelling the processes analyzed in the case study and all the life cycle inputs and outputs related to the functional unit were characterised during life cycle impact assessment (LCIA) phase into potential impacts according to the TRACI v.2.1 impact assessment methodology. The results of the case study showed that the mixtures incorporating 15 and 30% of RCA can be considered as eco-friendly alternatives to the conventional mixture (i.e. no RCA content), as both allow reductions in all impact categories scores. On the contrary, the mixture that contains 45% of RCA denoted a lower environmental performance than that of the conventional mixture

First-Principles Study of Substitutional Metal Impurities in Graphene: Structural, Electronic and Magnetic Properties

We present a theoretical study using density functional calculations of the structural, electronic and magnetic properties of 3d transition metal, noble metal and Zn atoms interacting with carbon monovacancies in graphene. We pay special attention to the electronic and magnetic properties of these substitutional impurities and found that they can be fully understood using a simple model based on the hybridization between the states of the metal atom, particularly the d shell, and the defect levels associated with an unreconstructed D3h carbon vacancy. We identify three different regimes associated with the occupation of different carbon-metal hybridized electronic levels: (i) bonding states are completely filled for Sc and Ti, and these impurities are non-magnetic; (ii) the non-bonding d shell is partially occupied for V, Cr and Mn and, correspondingly, these impurties present large and localized spin moments; (iii) antibonding states with increasing carbon character are progressively filled for Co, Ni, the noble metals and Zn. The spin moments of these impurities oscillate between 0 and 1 Bohr magnetons and are increasingly delocalized. The substitutional Zn suffers a Jahn-Teller-like distortion from the C3v symmetry and, as a consequence, has a zero spin moment. Fe occupies a distinct position at the border between regimes (ii) and (iii) and shows a more complex behavior: while is non-magnetic at the level of GGA calculations, its spin moment can be switched on using GGA+U calculations with moderate values of the U parameter.Comment: 13 figures, 4 tables. Submitted to Phys. Rev. B on September 26th, 200

Image Management in a Touristic Destination: A Qualitative Approach Analysis of the Border City of Ciudad Juarez, Mexico

This paper summarizes an academic experience. It has been made by the contributions of a group of experts from a Mexican university participating in a discussion panel called "Image of a Touristic Destination". This was done within the framework of the activities carried out during the 8va. Catedra Patrimonial "Sergio Molina" on October 19-21, 2016. The purpose of this paper is to analyze the process of image management of a border touristic destination through the experience of Ciudad Juárez, in order to obtain an improvement in it. The concept of image is analyzed from its components of responsibility and participation in management between Government (message), Society (context), and Universities (management). The methodological approach selected was exploratory. The grounded theory method was selected and thematic analysis with the support of the Atlas-ti software was made. Suggestions are offered for actions which seek to highlight the positive aspects of the city as a touristic destination. The importance of generating responsibility and participation within a social network was highlighted. It was recommended to take advantage of the economic and intellectual resources in education of the Juarez society so that they can know their culture and history

An investigation into the effect of customised insoles on plantar pressures in people with diabetes

Introduction High plantar pressures have been shown to be a key risk factor for foot ulceration in people with diabetes. Consequently, patients are often prescribed insoles designed to reduce pressure. New technologies, such as plantar pressure measurement devices and 3D foot scanners, have the potential to improve insole design. However, it is not clear to what extent such technologies are currently being used by clinicians, nor which other factors influence clinical decision making in the prescription of insoles. Furthermore, there has been minimal previous research designed to understand how best to use technology to improve insole design for patients with diabetes. Methods This thesis comprises four separate studies: a first qualitative study aimed at understanding the factors influencing practitioner decision making and the current role of technology. Three other quantitative studies were then performed to help understand the potential role of technology in designing insoles for medium-risk patients with diabetes and neuropathy. For each of these three studies, individually customised insoles were manufactured for every patient using CAD/CAM technology and data on both plantar pressure and foot shape. The first study investigated the reproducibility of plantar pressure collection in patients with diabetes and neuropathy while wearing the customised insoles, while the second investigated the effect of systematically varying two insole design features, metatarsal bar position and cushion material, on plantar pressures. In the final study, associations were investigated between changes in plantar pressure with different customised insole designs and specific structural and biomechanical foot characteristics of each participant. Results The findings of the qualitative study suggest that current clinical practice is based on training but that it develops in time based on practitioner’s clinical experience. Technology is not normally used because the data is considered too complex to use and interpret. However, practitioners agreed that they would use technology that is more user-friendly and focused on improving patient outcomes. The first quantitative study showed a relatively high level of pressure variability (up to 55 KPa under metatarsal heads) which we suggest is a characteristic of patients with diabetes and neuropathy. The second quantitative study showed that customised insoles which incorporate both a metatarsal bar and cushioning materials in front of the bar are effective in reducing peak pressures (PP). However, the optimum design was that which incorporated a combination of poron (cushioning material) with a metatarsal bar, located distal or on the point of PP. In the final quantitative study, specific individual characteristics which predicted PP changes were identified, such as tissue stiffness and joint range of movement (ROM). Based on these findings, some tentative recommendations for insole prescription were suggested. For example, to reduce PP under the 1st metatarsal when high tissue stiffness is present use a metatarsal bar just behind the PP combined with poron if there is a low range of movement of the 1st metatarsophalangeal joint. But if there is a high range of movement of the 1st metatarsophalangeal joint, a distal metatarsal bar with Poron should be used. Conclusion Taken together, the results of this work show that practitioners are willing to embrace more technology within their clinical practice and that it could be used to improve the efficacy of insoles designed to reduce plantar pressures for people with diabetes