One hand to school them all: the Society for the Construction of Educational Facilities in Chile (SCEE)

The experience of the Society for the Construction of Educational Facilities (SCEE; initials from the Spanish title) is a unique case in Chile of a public agency dedicated to a single task: designing and building the schools of the whole country. It lasted for fifty years, delivering a final product that constitutes the presence of the State throughout Chile to this day, even if its participation in public education has decreased dramatically in recent years. Totaling more than four thousand schools throughout the country, the SCEE's production shows, from its creation in 1937 to its final closure in 1987, the leading tendencies that oriented the discipline of architecture during its most active and polemic years. From the initial modernity of massive, brick-and-mortar buildings to the prefabricated and modular systems (in wood, steel or prefabricated concrete) of the 1960s and 1970s, the SCEE's production can be considered to be a showcase of modern heritage. But although most of its schools are still in use, they are subject to modifications and threats from the dynamics of the expansion of contemporary society.     

Changes in actin and tubulin expression in osteogenic cells cultured on bioactive glass‐based surfaces

The present study evaluated whether the changes in the labeling pattern of cytoskeletal proteins in osteogenic cells cultured on bioactive glass‐based materials are due to altered mRNA and protein levels. Primary rat‐derived osteogenic cells were plated on Bioglass® 45S5, Biosilicate®, and borosilicate (bioinert control). The following parameters were assayed: (i) qualitative epifluorescence analysis of actin and tubulin; (ii) quantitative mRNA and protein expression for actin and tubulin by real‐time PCR and ELISA, respectively, and (iii) qualitative analysis of cell morphology by scanning electron microscopy (SEM). At days 3 and 7, the cells grown on borosilicate showed typical actin and tubulin labeling patterns, whereas those on the bioactive materials showed roundish areas devoid of fluorescence signals. The cultures grown on bioactive materials showed significant changes in actin and tubulin mRNA expression that were not reflected in the corresponding protein levels. A positive correlation between the mRNA and protein as well as an association between epifluorescence imaging and quantitative data were only detected for the borosilicate. SEM imaging of the cultures on the bioactive surfaces revealed cells partly or totally coated with material aggregates, whose characteristics resembled the substrate topography. The culturing of osteogenic cells on Bioglass® 45S5 and Biosilicate® affect actin and tubulin mRNA expression but not the corresponding protein levels. Changes in the labeling pattern of these proteins should then be attributed, at least in part, to the presence of a physical barrier on the cell surface as a result of the material surface reactions, thus limiting fluorescence signals. Microsc. Res. Tech. 78:1046–1053, 2015. © 2015 Wiley Periodicals, Inc.     

Activated carbon from agave wastes (agave tequilana) for supercapacitors via potentiostatic floating test

To prepare an efficient supercapacitor, an activated carbon from agave wastes was prepared and their electrochemical performance was evaluated as a novel electrode for supercapacitor. The carbon was prepared by two thermal pyrolysis processes under nitrogen atmosphere. The first pyrolysis was achieved at 500 °C until the charring of the bagasse; in the second pyrolysis step, the char was impregnated with different mass ratios of KOH (1:2–1:4) and thermally treated at 800 or 900 °C, for 1 h under N₂ flow. The textural analysis showed that the activated carbon had a specific surface area of 1462 m² g^?1 and depicted a type I isotherm (IUPAC) characteristic of a microporous carbon. Raman spectroscopy and XRD measurements confirm that the activated carbon contains a small graphitization degree and a disordered structure. The electrochemical study of the symmetric carbon supercapacitor was carried out in 1 M Li₂SO₄ solution as the electrolyte. The electrochemical performance of the coin cell supercapacitor was evaluated under an accelerated aging floating test consisting of potentiostatic steps at different voltages (1.5, 1.6 and 1.8 V) for 10 h followed by galvanostatic charge/discharge sequences, and the overall procedure summarized a floating time up to 200 h. The highest capacitance was observed at a floating voltage of 1.5 V, with a large initial specific capacitance of 297 F g^?1.

     

Synthesis and characterisation of porous polymer microneedles

This paper presents a study on the synthesis of porous polymers with an application to microneedles. A range of Poly (ethylene glycol-co-methacrylic acid) polymers are synthesised using bulk polymerisation techniques to produce porous polymers with various strength and fluid transport characteristics. The synthesised materials are morphologically and mechanically characterised. Using different porogens in the polymer synthesis results in different mechanical strength and fluid flow characteristics. The results indicate that the fluid flow characteristics of the polymers can be sacrificed to improve strength. Optimum polymer strength can be attained by synthesising polymers with macropores that are interconnected via nanopores using the minimum amount of porogenic solvents.     

A new Multiobjective Artificial Bee Colony algorithm to solve a real-world frequency assignment problem

Artificial bee colony (ABC) is a recently introduced algorithm that models the behavior of honey bee swarm to address a multiobjective version for ABC, named Multiobjective Artificial Bee Colony algorithm (MO-ABC). We describe the methodology and results obtained when applying the new MO-ABC metaheuristic, which was developed to solve a real-world frequency assignment problem (FAP) in GSM networks. A precise mathematical formulation for this problem was used, where the frequency plans are evaluated using accurate interference information taken from a real GSM network. In this paper, our work is divided into two stages: In the first one, we have accurately tuned the algorithm parameters. Then, in the second step, we have compared the MO-ABC with previous versions of distinct multiobjective algorithms already developed to the same instances of the problem. As we will see, results show that this approach is able to obtain reasonable frequency plans when solving a real-world FAP. In the results analysis, we consider as complementary metrics the hypervolume indicator to measure the quality of the solutions to this problem as well as the coverage relation information.     

COMPARATIVE ANALYSIS OF A HYBRID DE ALGORITHM WITH THE VNS ALGORITHM AND ITS VARIATION SVNS TO SOLVE A REAL-WORLD FREQUENCY ASSIGNMENT PROBLEM

The Frequency Assignment is a very important task in the planning of the GSM networks, and it still continues to be a critical task for current (and future) mobile communication operators. In this work, we compare a hybrid Differential Evolution algorithm with the Variable Neighbourhood Search algorithm and also its variant Skewed Variable Neighbourhood Search to solve a real-world Frequency Assignment problem (FAP) in GSM Networks. The results that are shown use accurate interference information. That information was also adopted by other researchers and it represents a real GSM network, granting, therefore, an really important applicability. Furthermore, we have analyzed and compared our approach with other algorithms proposed so far to this problem. Hence, our approach using the SVNS algorithm has proven to be efficient in solving this problem, and permitted us to obtain good results. In fact, with this work we have contributed to the FAP problem with an additional comparison between approaches using metaheuristics based on trajectory (VNS and SVNS) and others based on population (DE).