Controlled Rate Thermal Analysis (CRTA) as New Method to Control the Specific Surface in Hydroxyapatite Thin Coatings

The control of the texture in synthetic hydroxyapatite ceramics had limited their application in the field of the materials for bone implantation, even more when it is used as a filling in cements and other formulations in orthopedic surgery. The present article shows preliminary results demonstrating the effectiveness of a modification of the controlled rate thermal analysis (CRTA), developed by J. Rouquerol, used for the preparation of ceramic materials with controlled textural characteristics, during the formation of ceramic powders of synthetic hydroxyapatite at low temperatures. The thermal treatments of the hydroxyapatite were carried out in a device connected to a computer, to control temperature and pressure system, keeping the decomposition speed constant. Results, reported when preparing ceramic powders of hydroxyapatite at 300 and 850°C under controlled pressure, using synthetic hydroxyapatite with a Ca/P molar ratio equal to 1.64, were checked using IR spectroscopy and X‐ray diffraction, showed that the formed phase corresponds to that of crystalline hydroxyapatite, even at 300°C of maximum temperature. Values of specific surface (BET) between 17 and 66 m2/g, with pore size in the range of 50–300 Å in both cases are obtained by N2 absorption isotherms, when analyzing the isotherms of nitrogen absorption

Symplectic Geometry of a Moduli Space of Framed Higgs Bundles

21 pages, minor modificationsLet $X$ be a compact connected Riemann surface and $D$ an effective divisor on $X$. Let ${\mathcal N}_H(r,d)$ denote the moduli space of $D$-twisted stable Higgs bundles (a special class of Hitchin pairs) on $X$ of rank $r$ and degree $d$. It is known that ${\mathcal N}_H(r,d)$ has a natural holomorphic Poisson structure which is in fact symplectic if and only if $D$ is the zero divisor. We prove that ${\mathcal N}_H(r,d)$ admits a natural enhancement to a holomorphic symplectic manifold which is called here ${\mathcal M}_H(r,d)$. This ${\mathcal M}_H(r,d)$ is constructed by trivializing, over $D$, the restriction of the vector bundles underlying the $D$-twisted Higgs bundles; such objects are called here as framed Higgs bundles. We also investigate the symplectic structure on the moduli space ${\mathcal M}_H(r,d)$ of framed Higgs bundles as well as the Hitchin system associated to it

Using zilpaterol in an intensive feeding system for steers in Yucatán, México.

The effect of zilpaterol, which is sold legally in Mexico, on growth and carcass yield and composition of zebu-type crossbred steers, was studied during the summer season in Mérida. A commercial product with a concentration of 4.8% of zilpaterol chlorhydrate was used, two treatments being randomly assigned to 95 finishing steers: control (C) and zilpaterol-treated (Z), during 33 days. All animals received the same finishing diet, composed of ground corn grain, soybean hulls, soybean meal, wheat bran, corn stalks, vegetable oil, and a vitamin-mineral premix (1.93 Mcal NEm and 1.29 Mcal NE g/kg; 13.2% CP). Post-slaughter warm and chilled carcass weights, and weight of internal fat were recorded. Fat thickness, area of the Logissimus muscle and marbling were measured between the 12th and 13th ribs. Carcass yield and yield grade were calculated. Steers in the Z group grew 3.1% faster and had heavier and leaner carcasses than those of the C group (P < 0.005). It was concluded that use of oral zilpaterol (0.14 mg/kg bodyweight daily equivalent) in finishing zebu-type steers, stimulates faster grains in weight of whole body and carcass and provides a more desirable carcass composition. (In Spanish)

Synthesis of Spherical 4R Mechanism for Path Generation using Differential Evolution

The problem of path generation for the spherical 4R mechanism is solved using the Differential Evolution algorithm (DE). Formulas for the spherical geodesics are employed in order to obtain the parametric equation for the generated trajectory. Direct optimization of the objective function gives the solution to the path generation task without prescribed timing. Therefore, there is no need to separate this task into two stages to make the optimization. Moreover, the order defect problem can be solved without difficulty by means of manipulations of the individuals in the DE algorithm. Two examples of optimum synthesis showing the simplicity and effectiveness of this approach are included.Comment: Submitted to Mechanism and Machine Theor

Do bad borrowers hurt good borrowers? A model of biased banking competition

This paper explores a two-bank model in which, first, one bank correctly estimates the probability of low-quality loan repayment while the other overestimates it, and second, both banks have identical convex costs when granting loans. In this context of optimistically biased banking competition, we show how the unbiased bank follows the biased competitor as long as the bias of the latter is not too large. This would favour bad borrowers, who get better credit conditions at the expense of good borrowers. As a consequence, the presence of a biased bank increases welfare as long as the expected default rate is sufficiently high. Contrariwise, in subprime markets, biased banking competition would be socially harmful.info:eu-repo/semantics/publishedVersio

Comparative study of hydroxyapatite coatings obtained by Sol-Gel and electrophoresis on titanium sheets

A comparative study of two coating methods on titanium (Ti) substrates, sol-gel and electrophoresis processes, was performed. Before coating, two different surface treatments were employed. The hydroxyapatite (HA) powder were characterized by infrared spectroscopy (FTIR) and X-ray diffraction (XRD) while coated samples were examined by using scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). Both techniques seem to be suitable to coat Ti. A previous surface treatment on metallic titanium seems to be fundamental to enhance coat uniformity and adhesion that was estimated by the adhesive tape test. The decrease in calcination temperature did not affect the coating adhesion.The authors thank the financial support of CAPES, CNPq, FAPERJ, and the cooperative project between CNPq/Brasil and MES/Cuba.Peer reviewe

Implicaciones del relieve sobre la baja atmósfera en una zona tropical y costera en México

Un círculo de 200 km de radio con centro en la nucleoeléctrica de Laguna Verde, México (19° 43,6’N, 96° 24’W) se puede dividir en un semicírculo sobre en el Golfo de México y otro sobre el continente. Este último se compone de dos planicies costeras con lomerío: una al sur-sudoeste y otra al norte. Hacia el poniente, el terreno es escarpado en los primeros 100 km de distancia y plano de gran altitud (más de 2000 m) los restantes 100 km. Los contrastes entre mar y continente, y entre los distintos tipos de relieve, generan comportamientos diferenciados en la atmósfera baja, que se exploran con datos de una campaña de mediciones realizada en el invierno de 2011 y otra en el verano de 2015, que constaron de sondeos con sodar, con dron y globo cautivo, así como estaciones termohigrométricas de superficie. Se mostrarán ejemplos de cómo el relieve tiene efectos diferenciados en las tendencias climáticas decadales, en el comportamiento de fenómenos meteorológicos de invierno como los frentes fríos, y en un día de verano bajo el influjo de los vientos alisios no perturbados.A circle of 200 km radius centered in nuclear power plant of Laguna Verde, Mexico (19°43.6’N, 96°24’W) can be divided in a semicircle on the Gulf of Mexico and another on the continent. The latter consists of two coastal plains with low hills: one south-southwest and other north. To the west the terrain is steep in the first 100 km away and plane at high altitude (2000 m) the remaining 100 km. The contrasts between sea and continent, and above this between different types of relief, generate different behaviors in the lower atmosphere, which are explored using data from a measurement campaign conducted in the winter of 2011 and again in the summer of 2015. Both them consisted of temperature and humidity soundings with sodar, drone, and tethersonde, and surface stations. This paper shows examples of how the relief has different effects on decadal climate trends, on the winter weather events such as cold fronts, and on a summer day under the soft trade winds.Proyecto Interacción superficie/atmósfera en la zona montañosa central de la vertiente del Golfo de México: observaciones y modelación a alta resolución (CONACyT CB183040)

Frozen ground and snow cover monitoring in Livingston and Deception islands, Antarctica: preliminary results of the 2015-2019 PERMASNOW project

Since 2006, our research team has been establishing in the islands of Livingston and Deception, (South Shetland archipelago, Antarctica) several monitoring stations of the active layer thickness within the international network Circumpolar Active Layer Monitoring (CALM), and the ground thermal regime for the Ground Terrestrial Network-Permafrost (GTN-P). Both networks were developed within the International Permafrost Association (IPA). In the GTN-P stations, in addition to the temperature of the air, soil, and terrain at different depths, the snow thickness is also monitored by snow poles. Since 2006, a delay in the disappearance of the snow layer has been observed, which could explain the variations we observed in the active layer thickness and permafrost temperatures. Therefore, in late 2015 our research group started the PERMASNOW project (2015-2019) to pay attention to the effect of snow cover on ground thermal This project had two different ways to study the snow cover. On the first hand, in early 2017 we deployed new instrumentation, including new time lapse cameras, snow poles with high number of sensors and a complete and complex set of instruments and sensors to configure a snow pack analyzer station providing 32 environmental and snow parameters. We used the data acquired along 2017 and 2018 years with the new instruments, together with the available from all our already existing sensors, to study in detail the snow cover. On the other hand, remote sensing data were used to try to map the snow cover, not only at our monitoring stations but the entire islands in order to map and study the snow cover distribution, as well as to start the way for future permafrost mapping in the entire islands. MODIS-derived surface temperatures and albedo products were used to detect the snow cover and to test the surface temperature. Since cloud presence limited the acquisition of valid observations of MODIS sensor, we also analyzed Terrasar X data to overcome this limitation. Remote sensing data validation required the acquirement of in situ ground-true data, consisting on data from our permanent instruments, as well as ad hoc measurements in the field (snow cover mapping, snow pits, albedo characterization, etc.). Although the project is finished, the data analysis is still ongoing. We present here the different research tasks we are developing as well as the most important results we already obtained about the snow cover. These results confirm how the snow cover duration has been changing in the last years, affecting the ground thermal behavior.info:eu-repo/semantics/publishedVersio

Variability of the air temperature and its comparison with MODIS Land Surface Temperature in the Hurd Peninsula of the Livingston Island, Antarctica, between 2000 and 2016

Ponencia presentada en: XVIII Congreso de la Asociación Española de Teledetección celebrado en Valladolid del 24 al 27 septiembre 2019.[ES]En los ambientes polares, tan vulnerables al cambio climático, el estudio de la temperatura es imprescindible. Por ello, y en el marco del proyecto PERMASNOW, en este trabajo hemos estudiado en detalle la variación de la temperatura del aire (Ta) en la península Hurd de la isla Livingston (Antártida) y hemos tratado de estimarla a partir de los datos de temperatura de la superficie terrestre (LST, por sus siglas en inglés) del sensor MODIS entre los años 2000 y 2016. Utilizamos datos de Ta media diaria obtenidos en seis puntos, tres estaciones meteorológicas de AEMET y tres estaciones del proyecto PERMASNOW: Juan Carlos I (JCI), Glaciar Johnson (GJ), Glaciar Hurd (GH), Incinerador (INC), Reina Sofía (RS) y Collado Ramos (CR), respectivamente. Los datos MODIS LST son los diurnos y nocturnos de los satélites Terra y Aqua. La tendencia en Ta se ha analizado mediante la regresión localmente ponderada (LOESS, por sus siglas en inglés) y la relación Ta -LST con regresiones lineales múltiples. Concluimos que Ta en el área de estudio varía: se observa en la estación JCI, más cercana a la costa, una tendencia al enfriamiento con valores entre –2,3 y –3,0°C década–1. En cambio, las estaciones más alejadas de la costa y de mayor altitud muestran una tendencia al calentamiento (entre +0,2 y +0,8°C década-1). Los mejores modelos de estimación de Ta a partir de LST y variables temporales se obtienen con los datos diurnos de Terra (R2 = 0,5-0,7; RSE = 2°C), exceptuando GJ, donde la variable LST no es significativa. Con la validación cruzada (CV) se aprecian también, excepto en GJ, mejores resultados con los datos diurnos de Terra (R2 CV = 0,5-0,6; RMSECV = 2,5-2,6°C). Finalmente, concluimos que los datos MODIS LST son útiles para estimar tendencias de Ta a largo plazo en el área de estudio.[EN]In polar zones, where satellite data are very useful due to the limited in situ data, it is therefore essential to study the air temperature behaviour. In the framework of the PERMASNOW project we estimated the air temperature (Ta) in the Hurd Peninsula of Livingston Island (Antarctica) from the land surface temperature (LST) data of the MODIS between 2000 and 2016. We worked with Ta data obtained at six stations (3 AEMET meteorological stations and 3 PERMASNOW project stations: Juan Carlos I (JCI), Johnson Glacier (JG), Hurd Glacier (HG), Incinerator (INC), Reina Sofia (RS) and Collado Ramos (CR), respectively. In addition, we analyzed daytime and nighttime LST data from the Terra and Aqua satellites. Locally weighted regression (LOESS) and multiple linear regressions were used for statistical analysis. We conclude that the Ta in the study area varies: a cooling trend with values between –2.3 and –3.0°C decade-1 is observed in JCI, which is closer to the coast. On the other hand, the stations farther from the coast and at higher altitudes show a warming trend (between +0.2 and +0.8°C decade-1). The best Ta models are obtained with Terra daytime data (R2 = 0.5-0.7 and RSE = 2°C), except JG, where the LST variable is not significant. With cross validation (CV), better results are also seen, except in JG, with the daytime Terra data (R2 CV = 0.5-0.6, RMSECV = 2.5-2.6°C). In summary, MODIS LST data are useful for estimating long-term Ta trends in the study area.Esta investigación fue posible gracias a la financiación de la Agencia Estatal de Investigación a través del proyecto PERMASNOW [CTM2014-52021-R], la ayuda de la Universidad de Oviedo al Grupo de Investigación RSApps en 2018 [PAPI-18-GR-2016-0005] y las ayudas obtenidas por A.C.-P. (“Severo Ochoa” del Gobierno del Principado de Asturias [BP17-151] y “Ayuda Predoctoral” de la Universidad de Oviedo)