Thermal conductivity and viscosity measurements of ethylene glycol-based Al2O3 nanofluids

The dispersion and stability of nanofluids obtained by dispersing Al2O3 nanoparticles in ethylene glycol have been analyzed at several concentrations up to 25% in mass fraction. The thermal conductivity and viscosity were experimentally determined at temperatures ranging from 283.15 K to 323.15 K using an apparatus based on the hot-wire method and a rotational viscometer, respectively. It has been found that both thermal conductivity and viscosity increase with the concentration of nanoparticles, whereas when the temperature increases the viscosity diminishes and the thermal conductivity rises. Measured enhancements on thermal conductivity (up to 19%) compare well with literature values when available. New viscosity experimental data yield values more than twice larger than the base fluid. The influence of particle size on viscosity has been also studied, finding large differences that must be taken into account for any practical application. These experimental results were compared with some theoretical models, as those of Maxwell-Hamilton and Crosser for thermal conductivity and Krieger and Dougherty for viscosity

Rheological non-Newtonian behaviour of ethylene glycol-based Fe2O3 nanofluids

The rheological behaviour of ethylene glycol-based nanofluids containing hexagonal scalenohedral-shaped α-Fe2O3 (hematite) nanoparticles at 303.15 K and particle weight concentrations up to 25% has been carried out using a cone-plate Physica MCR rheometer. The tests performed show that the studied nanofluids present non-Newtonian shear-thinning behaviour. In addition, the viscosity at a given shear rate is time dependent, i.e. the fluid is thixotropic. Finally, using strain sweep and frequency sweep tests, the storage modulus G', loss modulus G″ and damping factor were determined as a function of the frequency showing viscoelastic behaviour for all samples

Aggregation and phase equilibria of fluorinated ionic liquids

Grant SFRH/BD/100563/2014. IF/00190/2014 . IF/00210/2014. PTDC/EQU-EQU/29737/2017. PTDC/QEQ-FTT/3289/2014. IF/00210/2014/CP1244/CT0003. UID/QUI/50006/2019. POCI-01-0145-FEDER - 007265.In this work a specific family of ionic liquids, denominated fluorinated ionic liquids, with fluorine tags equal or longer than four carbon atoms, are fully characterized in order to understand their solubility and self-aggregation in aqueous solutions. The numerous combinations between cations and anions make these compounds a feasible option for the replacement of traditional and toxic surfactants used in the industrial and biomedical field. In this work, the increment of both hydrogenated and fluorinated side chain lengths, the influence of the cation headgroup (imidazolium and cholinium)as well as the difference between perfluorobutanesulfonate and perfluoropentanoate anions were studied. The liquid-liquid phase equilibria of fluorinated ionic liquids based on the perfluorobutanesulfonate anion with water were carried out. The self-aggregation behaviour of the different fluorinated ionic liquids in aqueous solutions was also determined using conductimetric titration, surface tension measurements and transmission electron microscopy. Several thermodynamic and surface parameters were obtained and used to discuss the aggregation process. These novel characterized fluorinated ionic liquids demonstrate an improved surface activity and aggregation behaviour, driven essentially by the increment of both hydrogenated and fluorinated chain lengths.authorsversionpublishe

Viscosity affected by nanoparticle aggregation in Al2O3-water nanofluids

An investigation on viscosity was conducted 2 weeks after the Al2O3-water nanofluids having dispersants were prepared at the volume concentration of 1-5%. The shear stress was observed with a non-Newtonian behavior. On further ultrasonic agitation treatment, the nanofluids resumed as a Newtonian fluids. The relative viscosity increases as the volume concentrations increases. At 5% volume concentration, an increment was about 60% in the re-ultrasonication nanofluids in comparison with the base fluid. The microstructure analysis indicates that a higher nanoparticle aggregation had been observed in the nanofluids before re-ultrasonication

Effectiveness of rotavirus vaccination in Spain

With the aim of determining rotavirus vaccine effectiveness (RVVE) in Spain, from Oct-2008/Jun-2009, 467 consecutive children below 2 years old with acute gastroenteritis (AGE) were recruited using a pediatric research network (ReGALIP-www.regalip.org) that includes primary, emergency and hospital care settings. Of 467 enrolled children, 32.3% were rotavirus positive and 35.0% had received at least one dose of any rotavirus vaccine. RRVE to prevent any episode of rotavirus AGE was 91.5% (95% CI: 83.7%-95.6%). RVVE to prevent hospitalization by rotavirus AGE was 95.6% (85.6-98.6%). No differences in RVVE were found regarding the vaccine used. Rotavirus vaccines have showed an outstanding effectiveness in Spain

Targeted detection of in vivo endogenous DNA base damage reveals preferential base excision repair in the transcribed strand

Endogenous DNA damage is removed mainly via base excision repair (BER), however, whether there is preferential strand repair of endogenous DNA damage is still under intense debate. We developed a highly sensitive primer-anchored DNA damage detection assay (PADDA) to map and quantify in vivo endogenous DNA damage. Using PADDA, we documented significantly higher levels of endogenous damage in Saccharomyces cerevisiae cells in stationary phase than in exponential phase. We also documented that yeast BER-defective cells have significantly higher levels of endogenous DNA damage than isogenic wild-type cells at any phase of growth. PADDA provided detailed fingerprint analysis at the single-nucleotide level, documenting for the first time that persistent endogenous nucleotide damage in CAN1 co-localizes with previously reported spontaneous CAN1 mutations. To quickly and reliably quantify endogenous strand-specific DNA damage in the constitutively expressed CAN1 gene, we used PADDA on a real-time PCR setting. We demonstrate that wild-type cells repair endogenous damage preferentially on the CAN1 transcribed strand. In contrast, yeast BER-defective cells accumulate endogenous damage preferentially on the CAN1 transcribed strand. These data provide the first direct evidence for preferential strand repair of endogenous DNA damage and documents the major role of BER in this process

Age-Related Neuronal Degeneration: Complementary Roles of Nucleotide Excision Repair and Transcription-Coupled Repair in Preventing Neuropathology

Neuronal degeneration is a hallmark of many DNA repair syndromes. Yet, how DNA damage causes neuronal degeneration and whether defects in different repair systems affect the brain differently is largely unknown. Here, we performed a systematic detailed analysis of neurodegenerative changes in mouse models deficient in nucleotide excision repair (NER) and transcription-coupled repair (TCR), two partially overlapping DNA repair systems that remove helix-distorting and transcription-blocking lesions, respectively, and that are associated with the UV-sensitive syndromes xeroderma pigmentosum (XP) and Cockayne syndrome (CS). TCR–deficient Csa−/− and Csb−/− CS mice showed activated microglia cells surrounding oligodendrocytes in regions with myelinated axons throughout the nervous system. This white matter microglia activation was not observed in NER–deficient Xpa−/− and Xpc−/− XP mice, but also occurred in XpdXPCS mice carrying a point mutation (G602D) in the Xpd gene that is associated with a combined XPCS disorder and causes a partial NER and TCR defect. The white matter abnormalities in TCR–deficient mice are compatible with focal dysmyelination in CS patients. Both TCR–deficient and NER–deficient mice showed no evidence for neuronal degeneration apart from p53 activation in sporadic (Csa−/−, Csb−/−) or highly sporadic (Xpa−/−, Xpc−/−) neurons and astrocytes. To examine to what extent overlap occurs between both repair systems, we generated TCR–deficient mice with selective inactivation of NER in postnatal neurons. These mice develop dramatic age-related cumulative neuronal loss indicating DNA damage substrate overlap and synergism between TCR and NER pathways in neurons, and they uncover the occurrence of spontaneous DNA injury that may trigger neuronal degeneration. We propose that, while Csa−/− and Csb−/− TCR–deficient mice represent powerful animal models to study the mechanisms underlying myelin abnormalities in CS, neuron-specific inactivation of NER in TCR–deficient mice represents a valuable model for the role of NER in neuronal maintenance and survival

Estudos Luso-Hispanos de História do Direito

El primer volumen de los Estudios Luso-Hispanos de Historia del Derecho/ Estudos Luso-Hispanos de História do Direito recoge los trabajos presentados en el ámbito de la segunda edición del EHLHD (Encuentro Hispano-Luso de Historiadores del Derecho/Encontro Hispano-Luso de Historiadores do Direito), celebrado los días 6, 7 y 8 de julio de 2017 en la Universidad Autónoma de Madrid.Presentación / Laura Beck Varela y María Julia Solla Sastre (pp. 9-12). -- Quando il diritto era ancora compatto. Perché la storia giuridica svizzera è così diversa? / Pio Caroni (pp. 13-43). -- El derecho municipal medieval de la Cataluña Nueva (siglos XIII-XVII) / Josep Serrano Daura (pp. 45-62). -- Algunas consideraciones sobre el régimen local cantábrico frente al fomento naval y forestal en la Corona de Castilla (c.1560-1570) / Alfredo José Martínez González (pp. 63-91). -- Organização judiciária e administração da justiça no Portugal filipino: a “reformaçam da justiça” de Filipe I de Portugal (1582) / Jorge Veiga Testos (pp. 93-121). -- El oficio de secretario en la doctrina jurídica de la Edad Moderna / Marina Rojo Gallego-Burín (pp. 123-149). -- Notas sobre la reforma municipal carolina en Sevilla: la representación del común / María del Mar Tizón Ferrer (pp. 151-165). -- Un programa ilustrado para la formación de juristas. El Plan de Estudios de Pablo de Olavide de 1768 / Fernando Liendo Tagle (pp. 167-198). -- La formación del jurista en el virreinato del Perú en las postrimerías del antiguo régimen / Carlos Tormo Camallonga (pp. 199-237). -- Propiedad moderna y alteridad indígena en Brasil (1755-1862) / Camilla de Freitas Macedo (pp. 239-270). -- Direito, política e sociedade: as Novas Conquistas de Goa durante o Perismo. Os contributos de Nery Xavier e Cláudio Lagrange / Luís Pedroso de Lima Cabral de Oliveira y João Pedro Caleira (pp. 271-303). -- Horizonte nacional, espacio tradicional. La construcción jurídica de la nación y el extranjero en la constitución de Cádiz / Iván Pastoriza Martínez (pp. 305-337). -- La disolución de los consejos: entre quiebras, confusiones y continuidad (1834-1836) / Antonio Manuel Luque Reina (pp. 339-371). -- Justicia legal y derecho judicial: la influencia de la jurisprudencia en la formación de la ciencia jurídica isabelina / Blanca Sáenz de Santa María Gómez-Mampaso (pp. 373-409). -- Nuevas etiquetas disciplinares y sus contiendas: las ciencias políticas ante el derecho en Francia (1871-1900) / Pedro Luis López Herráiz (pp. 411-449). -- O casamento na legislação de 1910 em Portugal. A mudança de paradigma nas relações familiares / Miriam Afonso Brigas (pp. 451-479). -- Primeira Lei do Contrato de Trabalho em Portugal: Lei nº 1.952, de 10 de Março de 1937 / Margarida Seixas (pp. 481-513). -- A Revisão Constitucional de 1971: o Projecto de Lei 6/X da “Ala Liberal” num contexto de tensões internas no Marcelismo / Filipe de Arede Nunes (pp. 515-543)

Determination of Transport Properties of Glycol-Based NanoFluids Derived from Surface Functionalized Graphene

Suspensions of nanometric-sized graphene platelets have been proposed recently as potential heat exchange working fluids, due to their remarkably enhanced thermal profile. Nevertheless, their use presents serious long-term stability issues. Due to this limitation, the nanoplatelets surface chemical functionalization has been postulated as a promising alternative to solve this problem. In this work, graphene nanoplatelets were functionalized following an oxidation-reduction process, and then dispersed in glycol as base fluid. The nanoparticles chemical profile was determined using XPS (x-ray photoelectron spectroscopy). The thermo-physical properties characterization of these nanofluids was performed by determining their viscosity and thermal conductivity, because of their impact on practical applications related with fluid flow and heat transfer. The effect of temperature and shearing time on viscosity were analyzed. Viscosity was measured with a stress-controlled rheometer. All samples show shear-thinning behavior with a very remarkable influence of temperature in their viscoelastic profile