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Compra pública sostenible y estratégica: una aproximación al concepto de rendición de cuentas en el proceso de la compra pública sostenible a través de indicadores
Get PDFLa presente tesis doctoral tiene como objetivo profundizar en el estudio de la rendición de
cuentas de una compra pública sostenible y estratégica. Para ello, esta tesis se asienta en un
marco teórico de tres pilares, que permite establecer un método objetivo capaz de comprobar si
la compra pública desempeña el papel mediador en la implementación de las prácticas
sostenibles. El primero de los pilares abarca las dimensiones o áreas de responsabilidad de la
compra pública sostenible (económica, legal, de equidad, ética y de la misión). El segundo,
considera la compra pública como un proceso. Y el tercero, examina cómo se rinden cuentas
sobre la efectividad de los objetivos políticos a través de indicadores, estudiando para ello, las
características cualitativas de la información contenida en ellos. Partiendo de este marco
teórico, esta investigación lleva a cabo un análisis documental y un estudio de caso como
métodos para explorar las prácticas de contratación en las administraciones públicas
Self-compacting concrete containing coarse recycled precast-concrete aggregate and its durability in marine-environment-related tests
Get PDFMarine environments are extremely challenging for the long-term durability of concrete. Prior validation of
concrete durability is therefore a prerequisite to guarantee its adequate performance under marine environmental conditions. In this study, the performance of Self-Compacting Concrete (SCC) with variable contents of
coarse Recycled Precast-Concrete Aggregate (RPCA) and two different cement contents is assessed in terms of
capillary water absorption, natural and accelerated carbonation, resistance to SO2 attack, and moist/dry performance in drinking water, marine water, and sulfate water. These tests are intended to simulate the conditions
of a marine environment. In general, the results showed that an SCC containing coarse RPCA of adequate
durability under marine conditions could be produced. On the one hand, porosity due to the presence of RPCA
increased less as the cement content was increased, which in turn reduced water absorption and SCC carbonation. For example, the effective porosity of the SCC was reduced by 25 % between day 28 and day 180,
following the addition of 100 % coarse RPCA. On the other hand, both the SO2-attack and the moist/dry tests
revealed that the weight of the SCC with RPCA underwent greater variations, due to the reactions of the cementhydration products with chlorides and sulfates, as well as salt deposition. However, SCC compressive strength
was never adversely affected, as the concrete strength increased up to 8 MPa after the drinking-water and the
sulfate-water moist/dry tests when using RPCA. According to both Fick’s and Parrot’s models, the projected
service life of all the mixes was over 100 years, regardless of the coarse RPCA content, making this sort of SCC a
feasible option for construction in marine environments.This research work was supported by the Spanish Ministry of Universities, MICINN, AEI, EU, ERDF and NextGenerationEU/PRTR [grant numbers PID2020-113837RB-I00; 10.13039/501100011033; TED2021-129715B-I00]; the Junta de Castilla y León (Regional Government) and ERDF [grant number UIC-231]; and, finally, the University of Burgos [grant number SUCONS, Y135.GI]
Full-scale sustainable structural concrete containing high proportions of by-products and waste
Get PDFThe construction industry in general is, through minor low-cost processing methods, converting
several of its by-products into viable materials; furthermore, some siderurgic sector by-products
are likewise of use. In this context, large-scale batches (mix volumes over 0.5 m3
) of good quality
structural concrete are proposed, in which two kinds of binder and two kinds of aggregate (steel
slag and recycled concrete) are used to perform four concrete mixtures, containing more than 80
% in mass of good-quality recycled materials. A batch of tests, both in the fresh and in the
hardened state, are performed, covering on-site placement and long-term properties, to guarantee
the suitability and the quality of the mixtures as structural concretes. Most of the results were
encouraging, mainly depending on the aggregate and the binder types that were used. The freshstate workability of all the test mixtures was good. All the results in terms of hardened properties,
strength (42 MPa in type I cement mixtures, and 32–38 MPa in type III cement mixtures), stiffness, long-term shrinkage, and microstructural state (porosity, permeability) were acceptable,
their quality depending on the type of each component. The good results of the mixtures based on
the slag-based binder deserve attention. Some weak points found were the slightly higher specific
weight of the slag aggregate mixes (amounting to more than 2.7 Mg/m3
), plastic shrinkage rates
(in some cases greater than 1.2–1.5 thousand), and loss of resistance against chlorine penetration
in recycled concrete mixes. However, drawbacks of that sort are no obstacle to their use in most
structural applications.The authors wish to express their gratitude to the following entities for the funding they provided: MCIN/AEI/10.13039/501100011033 and ERDF A way of making Europe, the European Union, and Next Generation EU/PRTR [PID2020-113837RB-I00; PID2021–124203OB-I00 and TED2021-129715B-I00]; the Junta de Castilla y León (Regional Government) and ERDF [UIC-231]; the Basque Government [IT1619-22 SAREN Research Group]; the University of Burgos [Y135. GI]
Review of the materials composition and performance evolution of green alkali-activated cementitious materials
Get PDFArtículo de revisiónAlkali-activated cementitious materials (AAMs) are a kind of green building materials compared to Portland cement components. This review considers the related research on the AAMs to systematically summarize the results on its materials
composition and performance infuencing factors. The precursor material is mainly industrial solid waste containing Al2O3
and SiO2. The alkali activator is compound containing caustic alkali and basic elements, which can provide an alkaline environment. Meanwhile, some new green precursors and alkali activators are summarized in this review. The main mechanism
of alkali-activated reaction is that the hydroxide ion from the alkali activator nucleophilically attacks the covalent bonds of
Al–O and Si–O in the precursor material, which generates Si(OH)4 and Al(OH)4
−. They generate three-dimensional network
gel of tetrahedral structure of [SiO4] and [AlO4]
− through polycondensation reaction, which forms cement stone-like block
material after setting and hardening. Too high or too low concentration of alkali activator is detrimental to the workability
and mechanical properties of AAMs. When the ratio of Na/K to Al is small, the mechanical properties of AAMs are reduced.
When the Ca content in the AAM is high, calcium ions enter the polycondensation chain and reduce the degree of polymerization and mechanical properties of the aluminosilicate gel phase and increase the shrinkage deformation. The hydration
products in the AAM are free of calcium hydroxide, calcium aluminate hydrate, ettringite, etc., and can resist the erosion
of acid and sulfate media. The main aim is to provide an informed outlook on the advantages and drawbacks of AAMs and
present a comprehensive review of the studies performed in this area
Identifying activity areas in a neanderthal hunting camp (the Navalmaíllo Rock Shelter, Spain) via spatial analysis
Get PDFSpatial analysis has been much used to examine the distribution of archaeological remains at Pleistocene sites. However, little is known about the distribution patterns at sites identified as hunting camps, i.e., places occupied over multiple short periods for the capture of animals later transported to a base camp. The present work examines a Neanderthal hunting camp (the Navalmaíllo Rock Shelter in Pinilla del Valle, Madrid, Spain) to determine whether different activities were undertaken in different areas of the site. A spatial pattern was detected with a main cluster of materials (lithic tools, faunal remains, and coprolites) clearly related to the presence of nearby hearths—the backbone of the utilised space. This main cluster appears to have been related to collaborative and repetitive activities undertaken by the hunting parties that used the site. Spatial analysis also detected a small, isolated area perhaps related to carcasses processing at some point in time and another slightly altered by water.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. AM is funded by a grant from the Junta de Castilla y León, financed in turn by European Social Funds via the Consejería de Educación (BDNS 376062). AA-F is supported by a Ph.D. grant from the Reale Foundation via the Fundación Atapuerca. This research was conducted within projects under the auspices of the Dirección General de Investigación of the Ministerio de Ciencia, Innovación y Universidades PGC 2018–094125-B-100 (MCIU/AEI/FEDER, UE), PGC 2018–093925-B-C32 (MICINN-FEDER), AGAUR (2017SGR1040 IPHES-URV), PGC 2018–093612-B-100, PID2021-122355NB-C31, PID2021-122355NB-C32 (Ministerio de Ciencia e Innovación—Agencia Estatal de Investigación), and funded by the I + D activities program for research groups run by the Education Secretariat of the Madrid Regional Government H2019/HUM-5840 (co-financed by the European Social Fund). The study was also partly funded by the Museo Arqueológico Regional de la Comunidad de Madrid (MAR) and Canal de Isabel II-Gestión
Effect of tempering temperature and grain refinement induced by severe shot peening on the corrosion behavior of a low alloy steel
No full textIn this study, the effect of tempering temperature on the corrosion behavior of a low carbon steel (F1272) was analyzed by means of electrochemical tests: linear polarization resistance, potentyodinamic polarization and electrochemical impedance spectroscopy (EIS) in freely aerated 3.5% NaCl solution, at room temperature. The results show that corrosion resistance of the steel increases with elevating tempering temperature from 200 to 500 °C and finally, to 680 °C. Additionally, a severe shot peening (SSP) treatment was applied in the sample with the best corrosion behavior (TT680), in order to modify the grain structure. Results evidence that corrosion resistance of the TT680 sample decreases after the applied SSP treatment (10A and 5000% coverage). Corrosion behavior is discussed through the different microstructural singularities induced both the heat treatments and the SSP.L.B. Peral is grateful for his Margarita Salas Postdoctoral contract (Ref.: MU-21-UP2021-030) funded by the University of Oviedo through the Next Generation European Union. P. Ebrahimzadeh is also grateful for his Predoctoral contract (Ref.: PAPI-21-PF-21) funded by the University of Oviedo and the Santander Bank
Investigating the Cytotoxicity of Ru(II) Polypyridyl Complexes by Changing the Electronic Structure of Salicylaldehyde Ligands
Get PDFA novel class of Ru(II)-based polypyridyl complexes with an auxiliary salicylaldehyde ligand [Ru(phen)2(X-Sal)]BF4 {X: H (1), 5-Cl (2), 5-Br (3), 3,5-Cl2 (4), 3,5-Br2 (5), 3-Br,5-Cl (6), 3,5-I2 (7), 5-NO2 (8), 5-Me (9), 4-Me (10), 4-OMe (11), and 4-DEA (12), has been synthesized and characterized by elemental analysis, FT-IR, and 1H/13C NMR spectroscopy. The molecular structure of 4, 6, 9, 10, and 11 was determined by single-crystal X-ray diffraction analysis which revealed structural similarities. DFT and TD-DFT calculations showed that they also possess similar electronic structures. Absorption/emission spectra were recorded for 2, 3, 10, and 11. All Ru-complexes, unlike the pure ligands and the complex lacking the salicylaldehyde component, displayed outstanding antiproliferative activity in the screening test (10 μM) against CCRF-CEM leukemia cells underlining the crucial role of the presence of the auxiliary ligand for the biological activity. The two most active derivatives, namely 7 and 10, were selected for continuous assays showing IC50 values in the submicromolar and micromolar range against drug-sensitive CCRF-CEM and multidrug-resistant CEM/ADR5000 leukemia cells, respectively. These two compounds were investigated in silico for their potential binding to duplex DNA well-matched and mismatched base pairs, since they showed remarkable selectivity indexes (2.2 and 19.5 respectively) on PBMC cells.This work is based upon research funded by Iran national science foundation (INSF) under project no.4005765
Nature of a Tetrabutylammonium Chloride–Levulinic Acid Deep Eutectic Solvent
Get PDFA deep eutectic solvent was formed by considering the mixtures of tetrabutylammonium chloride and levulinic acid, and it is studied via a combined theoretical and experimental approach. Physicochemical properties were measured as a function of temperature, providing a macroscopic characterization of the fluid. Quantum chemistry and classical molecular dynamics simulations were carried out for the nanoscopic characterization, providing attention to the nature, extension, and dynamics of the hydrogen bonding network, which is at the root of the properties of the fluid. The reported study allows multiscale characterization of this fluid as an archetypical example of a natural, low-cost, and sustainable fluid.This work was funded by Ministerio de Ciencia, Innovación y Universidades (Spain, project RTI2018-101987-B-I00), and European Union NextGenerationEU/PRTR funds. The authors also acknowledge SCAYLE (Supercomputación Castilla y León, Spain) for providing supercomputing facilities. The statements made herein are solely the responsibility of the authors
Repoblando desde el aula: propuesta de aprendizaje basado en proyectos para repoblar la Sierra de la Demanda en Geografía e Historia de 3º de la ESO
Get PDFLa despoblación rural es uno de los grandes problemas a los que se tendrá que enfrentar
nuestra sociedad en los próximos años, es por ello que crear líneas educativas desde la Educa ción Secundaria para concienciar y solucionar esta problemática son esenciales. En el presente
TFM se despliega una propuesta innovadora de intervención en el aula para la asignatura de
Geografía e Historia en 3º de la ESO. A lo largo de un curso escolar se propone utilizar una
metodología de ABP (Aprendizaje Basado en Proyectos) para que los alumnos por grupos desa rrollen un proyecto final en el que crearán un plan para repoblar el sector burgalés de la Sierra
de la Demanda. Para su elaboración se llevarán a cabo una serie de clases tanto explicativas
como prácticas en las que se ligarán gran parte de los contenidos del currículo de la asignatura
en torno al problema de la despoblación rural.Rural depopulation is one of the greatest problems that Spanish society will have to face
in the following years. Creating educational lines from Secondary Education to raise awareness
and solve this problem are essentials. In the present FMP an innovative proposal of intervention
in the classroom is presented for the subject of Geography and History in 3rd of Secondary.
Throughout a school year, it is proposed to use a FBL (Project Based Learning) methodology
so that students by groups develop a final project in which they will make a plan to repopulate
the Burgos sector of Sierra de la Demanda. For its preparation, a series of explanatory and
practical classes will be carried out in which a large part of the contents of the subject’s curriculum will be linked to the problem of rural depopulatio