Determination of thermal conductivity variation through Modified Transient Plane Source (MTPS), and its relationship with porosity variation on thermally treated Prada limestone

In this research, the variation of thermal conductivity with temperature of a limestone and its relationship with porosity is studied. Samples from Prada formation, a lower Cretaceous limestone from the Catalan Pyrenees (Spain), obtained from the Tres Ponts road tunnel were subjected to temperatures of 105, 300, and 600 °C and then cooled at a slow rate by air-cooling to laboratory temperature. Open porosity tests were determined before and after heating to evaluate the porosity increase and the micro-cracks growth. Complementarity, thermal conductivity was measured in the rock samples before and after the application of a thermal treatment by means of C-Therm TCi device, a Modified Transient Plane Source (MTPS). This is a non-invasive, quick, and precise method, when compared with other steady-state laboratory alternatives, widely used to directly determine thermal properties of rock samples. A clear decrease in the thermal conductivity of above 10% was observed for samples heated at 600 °C, probably due to a dramatic increase in porosity. The obtained results could be of great interest for the incorporation of the effect of temperature on rock in numerical models, to evaluate the potential impacts induced by eventual fires developed inside the Tres Ponts tunnel.This work was supported by the Department of Geological and Geotechnical Engineering, Universitat Politècnica de València

Temperature-Induced Explosive Behaviour and Thermo-Chemical Damage on Pyrite-Bearing Limestones: Causes and Mechanisms

In this investigation, two different varieties of ‘Prada’ limestones were studied: a dark grey texture, bearing quartz, clay minerals, organic matter and pyrites, and a light grey texture with little or no presence of such components. We have observed two effects of different intensity when heating the dark texture from 400 °C: (1) the explosion of certain samples and (2) greater thermal damage than in the light grey texture. Chemical and mineralogical composition, texture, microstructure, and physical properties (i.e. colour, open porosity, P and S-wave velocity) have been evaluated at temperatures of 105, 300, 400, and 500 °C in order to identify differences between textures. The violence of the explosive events was clear and cannot be confounded with ordinary splitting and cracking on thermally treated rocks: exploded samples underwent a total loss of integrity, displacing and overturning the surrounding samples, and embedding fragments in the walls of the furnace, whose impacts were clearly heard in the laboratory. Thermogravimetric results allowed the identification of a process of oxidation of pyrites releasing SO2 from 400 °C. This process jointly with the presence of microfissures in the dark texture, would cause a dramatic increase in pore pressure, leading to a rapid growth and coalescence of microcracks that leads to a process of catastrophic decay in rock integrity. In addition to the explosive events, average ultrasound velocities and open porosity showed a greater variation in the dark grey texture from 400 °C. That result also points towards a significant contribution of oxidation of pyrites on the thermo-chemical damage of the rock, among other factors such as the pre-existence of microfissures and the thermal expansion coefficient mismatch between minerals. Implications in underground infrastructure and mining engineering works are critical, as the explosive potential of pyrite-bearing limestones bears risk for mass fracturing and dramatic strength decay from 400 °C. Moreover, SO2 released has harmful effects on health of people and the potential to form acid compounds that corrode materials, shortening their durability and increasing maintenance costs.This work was supported by the Spanish Government [Grant number RTI2018-099052-B-I00] and by the Department of Geological and Geotechnical Engineering, Universitat Politècnica de València

Bullying victimization in young females with fragile-X-syndrome

The aim of this study is to investigate the risk associated with girls with fragile X syndrome (FXS) suffering bullying in the role of a victim and its effects on their adaptive behavior, socialization style, and emotional state. A neuropsychological assessment was carried out on a sample of 40 participants (26 FXS positive and 14 control group) using the following instruments: WISC-V, SENA, BAS-2, ABAS-II. The results show that the group of girls with FXS presented higher ratios of lack of social support and isolation from classmates. This finding suggests that problems with social interaction and communication in the group of girls with FXS could lead to difficulties in interpreting social signals and identifying situations of bullying correctly, placing them in a very vulnerable situation

Las reformas matrimoniales de 2015: una aproximación inicial

El presente trabajo trata sobre los cambios que la promulgación de la Ley 15/2015 de Jurisdicción Voluntaria ha introducido en parte del articulado del Código Civil. Concretamente, esta aproximación se va a referir a algunos de los preceptos relativos al matrimonio que se han visto modificados a consecuencia de dicha publicación

The pleiotropic effects of paricalcitol: Beyond bone-mineral metabolism

Secondary hyperparathyroidism (SHPT) is a common complication in patients with chronic kidney disease (CKD) that is characterised by elevated parathyroid hormone (PTH) levels and a series of bone-mineral metabolism anomalies. In patients with SHPT, treatment with paricalcitol, a selective vitamin D receptor activator, has been shown to reduce PTH levels with minimal serum calcium and phosphorus variations. The classic effect of paricalcitol is that of a mediator in mineral and bone homeostasis. However, recent studies have suggested that the benefits of treatment with paricalcitol go beyond PTH reduction and, for instance, it has a positive effect on cardiovascular disease and survival. The objective of this study is to review the most significant studies on the so-called pleiotropic effects of paricalcitol treatment in patients with CK

Vitamin D, vitamin D receptor and the importance of its activation in patients with chronic kidney disease

El déficit de vitamina D se asocia a distintas patologías, siendo especialmente significativa con la morbimortalidad en pacientes con enfermedad renal crónica (ERC). La pérdida progresiva de la función renal conduce a una reducción de calcitriol y alteración de la homeostasis de calcio, fósforo, FGF-23 y PTH, entre otros, los cuales influyen a su vez sobre la activación del receptor de vitamina D (RVD) y el desarrollo de hiperparatiroidismo secundario (HPS). El RVD media las acciones biológicas tanto de la vitamina D como de sus análogos sintéticos, actuando sobre distintos genes; existe una estrecha asociación entre niveles bajos de calcitriol y la prevalencia del HPS. Así, la activación de los RVD y la restricción de fósforo, entre otros, desempeñan un papel importante en el tratamiento de la «alteración óseo-mineral asociada a la ERC». La Sociedad Española de Nefrología, dada la uniforme e importante asociación con mortalidad y niveles altos de fósforo, aconseja su normalización, así como la de los niveles de calcidiol. Igualmente considera que, aparte de la utilización de activadores selectivos/no selectivos de RVD para la prevención y tratamiento del HPS, se podría asegurar la activación de los RVD en pacientes en diálisis, con vitamina D nativa o incluso bajas dosis de paricalcitol, independientemente de la PTH, dado que algunos estudios de cohortes y un metaanálisis reciente han observado una asociación entre el tratamiento con vitamina D activa y la disminución de la mortalidad en pacientes con ERC. En general, se considera que es razonable utilizar toda esta información para individualizar la toma de decisionesVitamin D deficiency has been linked to many different pathologies, especially with morbimortality in patients with chronic kidney disease. The progressive loss of renal function leads to calcitriol deficiency and homeostatic changes in calcium, phosphorus, FGF- 23 and PTH, among others. All these changes can also influence vitamin D receptor (VDR) activation and the development of secondary hyperparathyroidism (SHPT). The biologic actions of both vitamin D and its synthetic analogues are mediated by binding to the same VDR, acting on different genes. There is a narrow relationship between low levels of calcitriol and SHPT. The combined approach of VDR activation and phosphate restriction, among others, plays an important role in the early treatment of the chronic kidney disease-mineral and bone disorder (CKD-MBD). The Spanish Society of Nephrology, in order to reduce the uniform and significant association with CKD-associated mortality, calcidiol and high phosphate levels suggests normalization of phosphate as well as calcidiol levels in both CKD and dialysis patients. Moreover, it considers that, in addition to selective/non selective activation of VDR for the prevention and treatment of SHPT, VDR could be activated in dialysis patients by native vitamin D or even low paricalcitol doses, independently of PTH levels, as some cohort studies and a recent metaanalysis have found an association between treatment with active vitamin D and decreased mortality in patients with CKD. In general it is considered reasonable to use all this information to individualise decision makin

Thermal effects on the drilling performance of a limestone: relationships with physical and mechanical properties

This work evaluates the effect of high temperatures and cooling methods on the drillability of Prada limestone. Samples from boreholes drilled during the design stage of the Tres Ponts Tunnel in the Catalan south Pyrenean zone (Spain) were subjected to temperatures of 105, 200, 300, 400, and 600 °C, and then cooled at a slow rate or by quenching. Sievers’ J-value (SJ) and brittleness (S20) were determined on thermally treated samples, and the drilling rate index (DRI) was calculated for each temperature. The results show that thermal treatment implied a sustained increase in the drillability of the rock of up to 40% at 600 °C and a change in the drillability category (from medium to high). At 600 °C, SJ and S20 tripled and doubled, respectively, the initial values obtained for the intact rock. The results were inconclusive about the influence of the cooling method on the drilling performance of Prada limestone for the tested range of temperatures. The substantial improvement observed in the drillability of Prada limestone when heated, measured in terms of DRI, could help in the development of novel thermally-assisted mechanical excavation methods. Additionally, strong correlations between drillability variables (i.e., SJ and S20) and physical and mechanical variables of Prada limestone (i.e., P- and S-wave velocities, uniaxial compression strength, elastic modulus, and Poisson’s ratio) are proposed. Correlations will help make preliminary predictions of drillability based on properties such as uniaxial compression strength and ultrasound wave velocities.The authors wish to acknowledge David Benavente and Juan Carlos Canaveras from the University of Alicante, for their valuable help on mineralogical and petrographic description of the rock. Additionally, Kreum SA, Ayesa SA, Infraestructures de la Generalitat de Catalunya, S.A.U., and the Lleida regional roads authority (Servei Territorial de Carreteres de Lleida, Generalitat de Catalunya) for providing rock samples. This work was supported by the Department of Geological and Geotechnical Engineering, Universitat Politecnica de Valencia

Swelling potential reduction of Spanish argillaceous marlstone Facies Tap soil through the addition of crumb rubber particles from scrap tyres

[EN] During construction of road and railway projects, expansive soils may be encountered. Their use as construction material for embankments presents difficulties, due to their tendency to swell or shrink. Traditional solutions include mixing soil with cement or quicklime, or to import materials from other locations. As an alternative to these solutions, the present paper proposes a less expensive and more sustainable solution, consisting in mixing the natural expansive soil with rubber particles obtained from scrap tyres. Especially, the Facies Tap (a typical soil of southeastern Spain) is studied in this paper. This soil, which is mainly a white argillaceous marlstone, is mixed with six different amounts of rubber content (2.5, 5, 10, 15, 20 and 25% in terms of weight) and submitted to several geotechnical tests, including compaction, free swelling, unidimensional consolidation, direct shear testing and undrained shear compression. The addition of rubber particles to the soil up to a 15% makes it lighter and less prone to swelling, while compressibility remains similar to the natural soil and the drained shear strength slightly increases. Based on experimental results, the optimum rubber content mixed with the soil to prevent its swelling is established at around 3%.Hidalgo Signes, C.; Garzón-Roca, J.; Martínez Fernández, P.; Garrido De La Torre, ME.; Insa Franco, R. (2016). Swelling potential reduction of Spanish argillaceous marlstone Facies Tap soil through the addition of crumb rubber particles from scrap tyres. Applied Clay Science. 132-133:768-773. doi:10.1016/j.clay.2016.07.027S768773132-13