9,250 research outputs found

    RILEM interlaboratory study on the mechanical properties of asphalt mixtures modified with polyethylene waste

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    Acknowledgments The Swiss company Innoplastics is acknowledged for providing the waste plastics. Empais participation is supported by Swiss National Science Foundation grant SNF 205121_178991/1 for the project titled “Urban Mining for Low Noise Urban Roads and Optimized Design of Street Canyons”. The participation of University of Belgrade, Faculty of Civil Engineering, is supported by the Ministry of Education, Science, and Technological Development of the Republic of Serbia under research project No. 2000092.This research aims to determine if the observed improvements using polyethylene (PE) waste in asphalt binder translate into better performance at the asphalt mixture scale in the laboratory environment while overcoming the stability and homogeneity issues experienced at the binder level. This is accomplished through a round-robin multinational experimental program covering four continents, with the active participation of eleven laboratories within the RILEM TC 279-WMR. PE modified AC16 mixtures were prepared employing the dry process using local materials with the PE waste provided by one source. Various mechanical tests were performed to investigate the compactability, strength, moisture sensitivity, stiffness and permanent deformation. Compared to the control mixtures, the following observations were made for PE modified mixtures: easier to compact, lower time dependence of stiffness, higher elastic behavior, lower creep rate, and higher creep modulus. Furthermore, cyclic compression test results showed that the resistance to permanent deformation is improved when using PE in asphalt mixtures, whereas the wheel tracking tests showed relatively similar or better results when 1.5% PE was added to the control mixture. The wheel tracking test results in water showed an increase in deformation with increasing PE content. The interlaboratory investigation showed that the use of PE as a performance-enhancing additive in asphalt pavements is a viable, environmentally friendly option for recycling waste plastic and could potentially reduce the use of polymer additives in asphalt.Swiss National Science Foundation grant SNF 205121_178991/1Ministry of Education, Science, and Technological Development of the Republic of Serbia under research project No. 200009

    Use of nanomaterials to conserve the stone of the Roman Theatre of Cartagena

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    [EN] The Roman Theatre of Cartagena is an important example of the monumental architecture of Hispania. Various types of local stone were used in its construction, including a type of sandstone known as Tabaire. This paper describes the physical characteristics of Tabaire. We also identify its deterioration patterns and study its consolidation using lime nanoparticles and silicon dioxide (ethyl silicate). Initial analyses using the imaging techniques Optical Microscopy (OM), Scanning Electron Microscopy (SEM) and X-Ray Tomography (CT) show that it is an extremely porous, soft stone. The effectiveness of the consolidating treatments was verified using non-destructive methods based on identifying dispersion and penetrability in the substrate (OM and SEM) and detecting colour variation (CIE-L*a*b*) or minimally destructive methods, such as the peeling test and Shore-D hardness, to determine their effect on the characteristics of the material.[ES] El Teatro de Cartagena es un importante exponente de la arquitectura monumental de la Hispania romana. Para su construcción fueron utilizados diversos pétreos locales, entre ellos una arenisca conocida como Tabaire. Este artículo tiene como objetivo la caracterización física del Tabaire, así como la identificación de sus formas de deterioro y el estudio de su consolidación mediante nanopartículas de cal y de dióxido de silicio (silicato de etilo). Los análisis iniciales mediante técnicas de imagen como la Microscopía Óptica (OM), Microscopía Electrónica de Barrido (SEM) y Tomografía de Rayos X (CT) muestran que es una roca de elevada porosidad y escasa dureza. La eficacia de los tratamientos consolidantes se comprobó mediante métodos no destructivos, basados en la identificación de la dispersión y penetrabilidad en el sustrato (OM y SEM) y en la detección de la variación del color (CIE-L*a*b*), o mínimamente destructivos, como el peeling test y la dureza Shore-D, para conocer su incidencia en las características del material.Navarro-Moreno, D.; Martínez-Arredondo, A.; García-Vera, VE.; Lanzón, M. (2023). Uso de nanomateriales para la conservación de la piedra del Teatro Romano de Cartagena. Loggia, Arquitectura & Restauración. (36):106-119. https://doi.org/10.4995/loggia.2023.193601061193

    Morfología de las ciudades silentes de Cartagena. Reflejos del urbanismo de la ciudad viva

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    La aspiración humana de ir más allá de la vida ha ocasionado diversas manifestaciones de grandeza que en ocasiones se han visto reflejadas en los lugares elegidos para alojar sus restos tras el momento final. Desde que en el s.XIX Cartagena acatara las disposiciones de la Real Cédula de Carlos III por la que se imponía emplazar los recintos funerarios extramuros de las ciudades, se establecieron en la misma dos cementerios que aún hoy siguen funcionando; el cementerio de San Antonio Abad (1806) y el de Nuestra Señora de los Remedios (1868). Esta comunicación pretende analizar las distintas morfologías urbanas ensayadas en estos camposantos para mostrar la diferente concepción de los dos espacios y el reflejo en la ciudad viva de los modelos urbanos con que fueron concebidas ambas ciudades silentes. El primero, imitó modelos racionales como el que Ferdinando Fuga había practicado en Italia, donde bajo ideales ilustrados; vivos y muertos serían igualados en el momento final, y el segundo fue proyectado como un cementerio romántico en el que los hombres ilustres de la Cartagena decimonónica construyeron sus panteones a imagen de las mansiones emplazadas en la otra ciudad

    A T-PROPER KARHUNEN-LOÈVE EXPANSION AND ITS APPLICATION TO THE PROBLEM OF SIMULATION

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    The paper addresses the Karhunen-Loeve series representation in the tessarine domain. Based on augmented statistics, a tessarine widely linear Karhunen-Loeve expansion is defined. Then, the impact of T-properness on this representationis analyzed, leading to a T-proper Karhunen-Loeve expansion that means a dimensionality reduction. Furthermore, this series representation serves as a versatile simulation tool, valid for both stationary and non-stationary, Gaussian and non-Gaussian random signals. Finally, the applicability of the simulation technique proposed is examined numerically

    Vascular Dysfunction in a Transgenic Model of Alzheimer's Disease: Effects of CB1R and CB2R Cannabinoid Agonists

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    There is evidence of altered vascular function, including cerebrovascular, in Alzheimer's disease (AD) and transgenic models of the disease. Indeed vasoconstrictor responses are increased, while vasodilation is reduced in both conditions. β-Amyloid (Aβ) appears to be responsible, at least in part, of alterations in vascular function. Cannabinoids, neuroprotective and anti-inflammatory agents, induce vasodilation both in vivo and in vitro. We have demonstrated a beneficial effect of cannabinoids in models of AD by preventing glial activation. In this work we have studied the effects of these compounds on vessel density in amyloid precursor protein (APP) transgenic mice, line 2576, and on altered vascular responses in aortae isolated ring. First we showed increased collagen IV positive vessels in AD brain compared to control subjects, with a similar increase in TgAPP mice, which was normalized by prolonged oral treatment with the CB1/CB2 mixed agonist WIN 55,212-2 (WIN) and the CB2 selective agonist JWH-133 (JWH). In Tg APP mice the vasoconstriction induced by phenylephrine and the thromboxane agonist U46619 was significantly increased, and no change in the vasodilation to acetylcholine (ACh) was observed. Tg APP displayed decreased vasodilation to both cannabinoid agonists, which were able to prevent decreased ACh relaxation in the presence of Aβ. In summary, we have confirmed and extended the existence of altered vascular responses in Tg APP mice. Moreover, our results suggest that treatment with cannabinoids may ameliorate the vascular responses in AD-type pathology.This work was supported by the Council of Madrid (S- BIO/0170/2006 and P2010/BMD-2349 to MLC) and by Instituto de Salud Carlos III/FISS (PI12/00590 to TT). AM received a fellowship from the Spanish Ministry of Education and Science and JN-D from FISS. Dr. R. Martínez-Murillo is acknowledged for preliminary EM experiments.Peer reviewedPeer Reviewe

    Solar abundance corrections derived through 3D magnetoconvection simulations

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    We explore the effect of the magnetic field when using realistic three-dimensional convection experiments to determine solar element abundances. By carrying out magnetoconvection simulations with a radiation-hydro code (the Copenhagen stagger code) and through a-posteriori spectral synthesis of three Fe I lines, we obtain evidence that moderate amounts of mean magnetic flux cause a noticeable change in the derived equivalent widths compared with those for a non-magnetic case. The corresponding Fe abundance correction for a mean flux density of 200 G reaches up to ~0.1 dex in magnitude. These results are based on space- and time-averaged line profiles over a time span of 2.5 solar hours in the statistically stationary regime of the convection. The main factors causing the change in equivalent widths, namely the Zeeman broadening and the modification of the temperature stratification, act in different amounts and, for the iron lines considered here, in opposite directions; yet, the resulting Δlogϵ(Fe)|\Delta\log\epsilon_{\odot}(Fe)| coincides within a factor two in all of them, even though the sign of the total abundance correction is different for the visible and infrared lines. We conclude that magnetic effects should be taken into account when discussing precise values of the solar and stellar abundances and that an extended study is warranted.Comment: ApJ accepte

    Evaluation of circulating type I procollagen propeptides in patients with Paget's disease of bone

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    We evaluated circulating aminoterminal and carboxyterminal propeptides of type I procollagen and total alkaline phosphatase levels in eighty consecutive patients affected by Paget's disease of bone. We compared the biochemical data with the extent of bone disease calculated on the basis of the bone scintigraphic indices. Serum aminoterminal propeptide of type I procollagen levels were high in 77% of patients, serum carboxyterminal propeptide of type I procollagen levels in 22% and serum total alkaline phosphatase levels in 76%. We found significant correlations between the three markers studied. The three biochemical markers correlated significantly with the bone scintigraphic activity indices, but the highest correlation coefficient was between the aminoterminal propeptide and total alkaline phosphatase. We conclude that there is a discrepancy between serum levels of the propeptides studied in relation to Paget's disease of bone. The sensitivity of the carboxyterminal propeptide of type I procollagen in this disease is low. In contrast the aminoterminal propeptide may be as sensitive a marker for the evaluation of this disorder as total alkaline phosphatase, and in addition may be more specific

    Museo Arqueológico de Sevilla (1879-2017): 138 años de historia y algunos más

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    El presente trabajo se centra en la historia del Museo Arqueológico de Sevilla, una institución de especial relevancia en el contexto de la museística española. Su trayectoria y formación, hoy gestionada por la Consejería de Cultura de la Junta de Andalucía, muestra la incidencia del contexto histórico regional en la personalidad actual y recorrido de uno de los principales museos arqueológicos de nuestro país. Su análisis histórico revela que quizás se trate del modelo andaluz que mejor representa el paso de los antiguos studioli o gabinetes humanistas del siglo XVI hacia el museo público de finales del siglo XIX, y desde el anticuarismo a la consolidación de la ciencia arqueológica a mediados del siglo XX

    The Mpemba effect in spin glasses is a persistent memory effect

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    The Mpemba effect occurs when a hot system cools faster than an initially colder one, when both are refrigerated in the same thermal reservoir. Using the custom built supercomputer Janus II, we study the Mpemba effect in spin glasses and show that it is a non-equilibrium process, governed by the coherence length \xi of the system. The effect occurs when the bath temperature lies in the glassy phase, but it is not necessary for the thermal protocol to cross the critical temperature. In fact, the Mpemba effect follows from a strong relationship between the internal energy and \xi that turns out to be a sure-tell sign of being in the glassy phase. Thus, the Mpemba effect presents itself as an intriguing new avenue for the experimental study of the coherence length in supercooled liquids and other glass formers.Comment: Version accepted for publication in PNAS. 6 pages, 7 figure

    Heteroreceptor complexes formed by dopamine D1, histamine H3 and N-methyl-D-aspartate glutamate receptors as targets to prevent neuronal death in Alzheimer's disease

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    Alzheimer’s disease (AD) is a neurodegenerative disorder causing progressive memory loss and cognitive dysfunction. Anti-AD strategies targeting cell receptors consider them as isolated units. However, many cell surface receptors cooperate and physically contact each other forming complexes having different biochemical properties than individual receptors. We here report the discovery of dopamine D , histamine H , and N-methylD-aspartate (NMDA) glutamate receptor heteromers in heterologous systems and in rodent brain cortex. Heteromers were detected by coimmunoprecipitation and in situ proximity ligation assays (PLA) in the rat cortex where H receptor agonists, via negative cross-talk, and H receptor antagonists, via cross-antagonism, decreased D receptor agonist signaling determined by ERK1/2 or Akt phosphorylation and counteracted D receptormediated excitotoxic cell death. Both D and H receptor antagonists also counteracted NMDA toxicity suggesting a complex interaction between NMDA receptors and D -H receptor heteromer function. Likely due to heteromerization, H receptors act as allosteric regulator for D and NMDA receptors. By bioluminescence resonance energy transfer (BRET), we demonstrated that D or H receptors form heteromers with NR1A/NR2B NMDA receptor subunits. D -H -NMDA receptor complexes were confirmed by BRET combined with fluorescence complementation. The endogenous expression of complexes in mouse cortex was determined by PLA and similar expression was observed in wild-type and APP/PS1 mice. Consistent with allosteric receptor-receptor interactions within the complex, H receptor antagonists reduced NMDA or D receptor-mediated excitotoxic cell death in cortical organotypic cultures. Moreover, H receptor antagonists reverted the toxicity induced by ß -amyloid peptide. Thus, histamine H receptors in D -H -NMDA heteroreceptor complexes arise as promising targets to prevent neurodegeneration
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