[en] The objective of this case study is to analyze the use of prefabricated concrete systems and it´s incidence on the cost per square meter of construction in Ecuador. The analysis will be held for structural elements of buildings, comparing prefabricated systems to the system of reinforced concrete porticoes in situ, considered as the system traditional, taking into account its impact on both direct and indirect costs. Given the socioeconomic environment, it is important to study the economically viability for the Ecuadorian construction sector to begin to industrialize, using new methods to execute the structure of the buildings. The socio-economic situation that we find in Ecuador is very different from the one in Spain, not only on the basis that Spain has a much more developed industry but also from the point of view of the cost of labor that exists in these countries, which are very distant from each other.

[en] The activities in construction, excavation, earthworks and tunnels, with risk of falling height or burial appear specifically in section H of Annex I, Especially Dangerous Activities, Royal Decree 39/1997, of January 17, by which approves the Regulation of Prevention Services. Having said the above and seen the high number of incidents and accidents at work that year after year show the statistics of this sector, it is not unfounded to understand construction as a dangerous activity. If it is not incomprehensible, it draws attention to the fact that Royal Decree 1627/97 of October 24, which establishes minimum safety and health provisions in construction works does not prevent a young person from giving his first work steps providing their services in the work. In the year 2007 it has to be the IV General Agreement of the construction sector, which in a ^blunt way prohibits hiring people who have not yet reached the age of 18, the minimum age to work in construction that until then was in 16 years old. It is hard to understand that 10 years have to pass before, allow the expression, put a stop to and tackle such an irrational situation: there is no reason to describe it in this way. However, today, in construction, there is still another Kafkaesque situation, no less absurd or anguished: the presence on the work of foreign workers who neither speak nor understand a minimum of any of the official languages of this country.

[en] Currently in Spain there are more than 20 ''Data Banks''or ''Databases''with prices for construction, from which you can obtain parameters such as prices and yields for the realization of work budgets. These precedents are applicable for a specific autonomous community or geographical area, in some cases there is more than one ''Database''to which to go to obtain said values. The study is carried out for the autonomous communities of Castilla la Mancha, Madrid, Castilla y León, the Balearic Islands and Catalonia, using the databases; ''Price center'', ''PREOC'', ''ICCI'', ''ITEC'', ''COOAT''and CYPE Ingenieros, as appropriate, the article is based on a new work with 5,000 m2 built, according to the databases updated to 2017.

[en] The construction sector frequently presents delays and cost overruns during the execution of projects. These delays are due to a series of technical and administrative problems that affect the quality, cost and delivery time. Although there are several reasons that may lead to poor work development, the experience and professional practice have determined that, regardless of the magnitude of the management planning, projects are rarely complete within the planning. This forces us to think, from the perspective of the organizational level, that one of the causes of this problem is related to human resources, specifically to the selection processes, internal control and retention of personnel. Currently, high turnover and absenteeism are two variables that exist in all organizations and have had a significant impact on the management of information and knowledge transferring between projects. In order to improve the efficiency in the construction of projects, it is necessary to change and effectively organize all work processes, recognizing that knowledge, especially in construction companies, is one of the most important assets within the company. For this reason, it has been considered that knowledge management is an approach that could give good results if it is implemented in construction companies.

[en] Thanks to the existence of technological applications such as pre-dimensionators that allow us to obtain a budget for the execution of construction material quickly, we proceed to analyze the operation of these programs by obtaining a budget and comparing it with the construction cost of a work already executed. To determine the work to be analyzed, first proceed to determine the type of construction that is currently carried out in the municipalities of the community of Madrid.

[en] The use of titanium and its alloys in applications with the presence of friction is limited due to low hardness and reduced tribological properties. Some surface treatments are available in order to correct these problems, like the thermal surface treatment by means of nitrogen gaseous diffusion at high temperature. Nitrogen enters into the materials by diffusion, creating a surface layers of increased hardness. Oligocyclic fatigue behaviour in air of Ti6Al4V alloy has been studied. Results show a reduction of oligocyclic fatigue loads up to 10% compared to the not-treated materials. Studies suggest it is not related to the titanium nitride surface layer, but to microstructural changes caused by the high temperature treatment. (Author) 7 refs

[en] This study aims to improve the osseointegration of titanium implants through surface immobilization of peptides that induce a beneficial biological response. This was carried out biofunctionalizating titanium surfaces by silanization and subsequent covalent binding of a peptide with a sequence that promotes cell adhesion. Objective: The development of a new technique of immobilization of oligopeptides on the surface of titanium by using 3-chloropropyltrietoxisilane (CPTES) as bonding agent between the surface of titanium and the peptide. Materials and methods: A physicochemical characterization of the surfaces through the techniques of XPS, ToF-SIMS and contact angle was performed. Also cell adhesion studies have been conducted to evaluate in vitro biological response. Results: Through the process of silanization the titanium surface is completely covered with CPTES, which allows the subsequent accession of oligopeptides. The cell adhesion results show a higher cell adhesion and cell extension on biofunctionalized samples. Conclusions: We developed a system of covalent binding of oligopeptides on titanium surfaces that can modify the biological response of the attached cells.

[en] In this work the 2,5-diiodo-8-quinolyl methacrylate (IHQM), is proposed as a new radiopaque agent. The addition of the iodine containing methacrylate provided a statistically significant increase in the tensile strength, fracture toughness and ductility, with respect to the barium sulphate containing cement. This effect was attributed to the fact that the use of a radiopaque monomer eliminated the porosity associated to the barium sulphate particles. However, since fatigue resistance is one of the main properties required to ensure a good long-term performance of permanent pros these, as is the case of acrylic bone cements, it is important to compare the fatigue properties of this new bone cement formulation with the radiolucent and the BaSO₄ containing bone cements. The results show that the absence of inorganic particles with no matrix adhesion plays a negative role when the fatigue crack propagation is considered. (Author) 26 refs

[en] A method is described which enables one to deduce a range of possible values for the lifetime of a nuclear level when the delayed coincidence curve is experimentally given and the prompt curve is known only through some of its features. The method still applies when a prompt contribution is present. Experimental data in ¹⁸⁴Ir are analyzed. The method is also used to discuss results obtained with an experimental prompt curve in ¹⁸⁵Pt. (K.A.)

[en] The β⁺/EC decay of ¹⁸¹Au has been studied with mass separated sources from the ISOCELE facility. Main γ-rays which belong to the ¹⁸¹Au → ¹⁸¹Pt decay have been identified from X-γ coincidence measurements. A rotational band built on the 1/2 -[521] Nilsson state has been developed up to the 7/2^- state in ¹⁸¹Pt