Dielectric study of the glass transition: correlation with calorimetric data

The glass transition in amorphous poly(ethylene terephthalate) is studied by thermally stimulated depolarization currents (TSDC) and differential scanning calorimetry (DSC). The ability of TSDC to decompose a distributed relaxation, as the glass transition, into its elementary components is demonstrated. Two polarization techniques, windows polarization (WP) and non-isothermal windows polarization (NIW), are employed to assess the influence of thermal history in the results. The Tool-Narayanaswami-Moynihan (TNM) model has been used to fit the TSDC spectra. The most important contributions to the relaxation comes from modes with non-linearity (x) around 0.7. Activation energies yield by this model are located around 1eV for polarization temperature (Tp) below 50C and they raise up to values higher than 8eV as Tp increases (up to 80C). There are few differences between results obtained with WP and NIW but, nonetheless, these are discussed. The obtained kinetic parameters are tested against DSC results in several conditions. Calculated DSC curves at several cooling and heating rates can reproduce qualitatively experimental DSC results. These results also demonstrate that modelization of the non-equilibrium kinetics involved in TSDC spectroscopy is a useful experimental tool for glass transition studies in polar polymers.Comment: 13 pages, 2 tables, 10 figures; minor change

Control of the degradation of silica sol-gel hybrid coatings for metal implants prepared by the triple combination of alkoxysilanes

Hybrid materials obtained by sol-gel process are able to degrade and release Si compounds that are useful in regenerative medicine due to their osteoinductive properties. The present work studies the behavior of new organic-inorganic sol-gel coatings based on triple mixtures of alkoxysilanes in different molar ratios. The precursors employed are methyl-trimethoxysilane (MTMOS), 3-glycidoxypropyl-trimethoxysilane (GPTMS) and tetraethyl-orthosilicate (TEOS). After optimization of the synthesis conditions, the coatings were characterized using 29Si nuclear magnetic resonance (29Si-MNR), Fourier transform infrared spectrometry (FT-IR), contact angle measurements, hydrolytic degradation assays, electrochemical impedance spectroscopy (EIS) and mechanical profilometry. The degradation and EIS results show that by controlling the amount of TEOS precursor in the coating it is possible to tune its degradation by hydrolysis, while keeping properties such as wettability at their optimum values for biomaterials application. The corrosion properties of the new coatings were also evaluated when applied to stainless steel substrate. The coatings showed an improvement of the anticorrosive properties of the steel which is important to protect the metal implants at the early stages of the regeneration process.The financial support of MAT2014-51918-C2-2-R, P11B2014-19 and Plan de Promoción de la Investigación from the Universitat Jaume I (Predoc/2014/25) is gratefully acknowledged. J. García-Cañadas acknowledge financial support from Ramón y Cajal programme (RYC-2013-13970). The experimental support of Raquel Oliver Valls and José Ortega Herreros is also acknowledged

Abundance of baleen whales in the European Atlantic

The abundance of fin whales (Balaenoptera physalus), sei whales (B. borealis) and minke whales (B. acutorostrata) was estimated from data collected during shipboard sightings surveys conducted as part of CODA and TNASS (Faroese block) in July 2007 in offshore waters of the European Atlantic west of the UK, Ireland, France and Spain, combined with data collected from shipboard and aerial surveys of European Atlantic continental shelf waters conducted as part of SCANS-II in July 2005. Double platform methods employing the trial-configuration method (BT-method) were used in all shipboard surveys. Analysis used Mark-Recapture Distance Sampling to account for animals missed on the transect line. Density surface modelling was undertaken to generate model-based abundance estimates and maps of predicted density. Estimates are presented for the SCANS-II and CODA survey areas. Estimates for the Faroese block of TNASS have been presented elsewhere. The abundance of fin whales in the CODA and SCANS-II areas was estimated as 19,354 (CV 0.24) for identified sightings and 29,512 (CV 0.26) when adjusted to include a proportion of unidentified large whale abundance (which included large baleen and sperm whales), prorated by number of sightings, because there were a large number of such sightings in one of the CODA survey blocks. The model-based estimate of identified fin whales was 19,751 (CV 0.17), more precise than the design-based estimate. Fin whales were mainly found in the southern part of the CODA survey area. Estimates based on identified sightings were comparable to those from the Spanish survey conducted as part of 1989 NASS but were larger if adjusted for a proportion of unidentified large whales. Sei whales were rare except in the southwest of the survey area; the estimate of abundance was 619 (CV 0.34) for identified sightings and 765 (CV 0.43) adjusted for a proportion of unidentified large whales. Minke whale abundance was estimated for shelf and offshore European Atlantic waters as 30,410 (CV 0.34). The model-based estimate was less precise and considerably larger

Meanings given to algebraic symbolism in problem posing

Some errors in the learning of algebra suggest students have difficulties giving meaning to algebraic symbolism. In this paper, we use problem posing in order to analyze the students’ capacity to assign meaning to algebraic symbolism and the difficulties that students encounter in this process depending on the characteristics of the algebraic statements given. We designed a written questionnaire composed of eight closed algebraic statements expressed symbolically, which was administered to 55 students who had finished their compulsory education and that had some previous experience in problem posing. In our analysis of the data, we examine both syntactic and semantic structures of the problem posed. We note that in most cases students posed problems with syntactic structures different to those given. They did not include computations within variables, and changed the kinds of relationships connecting variables. Students easily posed problems for statements with additive structures. Other differences in the type of problems posed depend on the characteristics of the given statements

VDR gene polymorphisms on risk of osteoporotic hip fracture in an adult population spanish

La osteoporosis es una enfermedad esquelética compleja multifactorial con un fuerte componente genético, caracterizada por un deterioro en la microestructura ósea que causa fragilidad ósea y un incremento en el riesgo de fracturas osteoporóticas. El gen VDR podría estar fuertemente involucrado en el riesgo de fractura. El objetivo de este trabajo fue investigar la asociación entre polimorfismos del gen VDR y la susceptibilidad a fractura de cadera (FC). Se reclutaron 147 pacientes andaluces (102 con factores de riesgos de fracturas osteoporóticas y 45 con metabolismo óseo normal). El aislamiento de ADN se realizó a partir de 300 mL de sangre, genotipando 2 SNPs: BsmI y FokI mediante PCRRFLP (PCR-Restriction Fragment Length Polymorphism). Todas las fracturas fueron confirmadas por rayos-X mientras que el riesgo de fracturas a través de la escala FRAX y DMO. Los resultados se evaluaron estadísticamente, considerando significativo valores de p<0,05. La edad media de los pacientes fracturados fue de 68,5 años, cuyas frecuencias alélicas fueron 64.7% G y 68.6% C para BsmI y FokI, respectivamente. La prevalencia de estos SNPs en la población caso fueron: 43,3% GA, 43.3% GG y 13,7% AA para BsmI y 49,0% CC, 39,20% CT, 11,8% TT para FokI. Las frecuencias de los alelos y genotipos no mostraron diferencias entre pacientes con riesgo de fracturas y pacientes control. Las frecuencias están acorde con las demostradas en HapMap para población europeacaucásica. No se encontró ninguna asociación significativa entre estos SNPs y la susceptibilidad a las FC en la población adulta andaluza.Osteoporosis is a multifactorial complex skeletal disease with strong genetic component, characterized by a deterioration of bone microstructure that causes bone fragility and an increased risk of osteoporotic fractures. VDR gene could be strongly involved in the risk of fracture. The aim of this study was to investigate the association between VDR gene polymorphisms and susceptibility to hip fracture (HF). 147 Andalusian patients were recruited (102 with risk factors for osteoporotic fractures and 47 with normal bone metabolism). DNA isolation was performed from 300 mL of blood, genotyping 2 SNPs: BsmI and FokI by PCR-RFLP (PCR-Restriction Fragment Length Polymorphism). All fractures were confirmed by X-rays while the risk of fractures through FRAX level and BMD. The results were statistically evaluated, considering significant p-values <0.05. The average age of fractured patients was 68.5 years, whose allele frequencies were 64.7% G and 68.6% C for BsmI and FokI, respectively. Prevalence of these SNPs in the case population were: 43.3% GA, 43.3% GG and 13.7% AA BsmI and 49.0 % CC, 39.2% CT, 11.8% TT for FokI. The frequencies of alleles and genotypes showed no differences between patients with and without risk of hip fracture. The frequencies are agree to HapMap for European-Caucasian population. It was found no significant association between these SNPs and susceptibility to HF in the adult population of Andalusia

Cetaceans in the Mediterranean Sea. Encounter rate, dominant species, and diversity hotspots

We investigated the presence and diversity of cetaceans in the Mediterranean Sea, analysing the data collected by 32 different research units, over a period of 15 years (2004–2018), and shared on the common web-GIS platform named Intercet. We used the encounter rate, the species prevalence, and the Shannon diversity index as parameters for data analysis. The results show that cetacean diversity, in the context of the Mediterranean basin, is generally quite low when compared with the eastern Atlantic, as few species, namely the striped dolphin, the bottlenose dolphin, the fin whale, and the sperm whale, dominate over all the others. However, some areas, such as the Alboran Sea or the north-western Mediterranean Sea, which includes the Pelagos Sanctuary (the Specially Protected Area of Mediterranean Interest located in the northern portion of the western basin), show higher levels of diversity and should be considered hotspots to be preserved. Primary production and seabed profile seem to be the two main drivers influencing the presence and distribution of cetaceans, with the highest levels of diversity observed in areas characterized by high levels of primary production and high bathymetric variability and gradient. This collective work underlines the importance of data sharing to deepen our knowledge on marine fauna at the scale of the whole Mediterranean Sea and encourages greater efforts in the networking process, also to accomplish the requirements of the Marine Strategy Framework Directive, with particular reference to Descriptor 1: biological diversity is maintained

Marine mammals and Good Environmental Status: Science, Policy and Society; Challenges and Opportunities

The Marine Strategy Framework Directive has become the key instrument for marine conservation in European seas. We review its implementation, focusing on cetacean biodiversity, using the examples of Spain and the Regional Seas Convention, OSPAR. The MSFD has been widely criticised for legal vagueness, lack of coordination, uncertainty about funding, and poor governance; its future role within EU Integrated Maritime Policy remains unclear. Nevertheless, the first stages of the process have run broadly to schedule: current status, environmental objectives and indicators have been described and the design of monitoring programmes is in progress, drawing on experience with other environmental legislation. The MSFD is now entering its critical phase, with lack of funding for monitoring, limited scope for management interventions, and uncertainty about how conservation objectives will be reconciled with the needs of other marine and maritime sectors, being among the main concerns. Clarity in governance, about the roles of the EU, Member States, Regional Seas Conventions and stakeholders, is needed to ensure success. However, even if (as seems likely) good environmental status cannot be achieved by 2020, significant steps will have been taken to place environmental sustainability centre-stage in the development of Integrated Maritime Policy for EU seas.Postprin

Validation of a small-animal PET simulation using GAMOS: a Geant4-based framework

onte Carlo-based modelling is a powerful tool to help in the design and optimization of positron emission tomography (PET) systems. The performance of these systems depends on several parameters, such as detector physical characteristics, shielding or electronics, whose effects can be studied on the basis of realistic simulated data. The aim of this paper is to validate a comprehensive study of the Raytest ClearPET small-animal PET scanner using a new Monte Carlo simulation platform which has been developed at CIEMAT (Madrid, Spain), called GAMOS (GEANT4-based Architecture for Medicine-Oriented Simulations). This toolkit, based on the GEANT4 code, was originally designed to cover multiple applications in the field of medical physics from radiotherapy to nuclear medicine, but has since been applied by some of its users in other fields of physics, such as neutron shielding, space physics, high energy physics, etc. Our simulation model includes the relevant characteristics of the ClearPET system, namely, the double layer of scintillator crystals in phoswich configuration, the rotating gantry, the presence of intrinsic radioactivity in the crystals or the storage of single events for an off-line coincidence sorting. Simulated results are contrasted with experimental acquisitions including studies of spatial resolution, sensitivity, scatter fraction and count rates in accordance with the National Electrical Manufacturers Association (NEMA) NU 4-2008 protocol. Spatial resolution results showed a discrepancy between simulated and measured values equal to 8.4% (with a maximum FWHM difference over all measurement directions of 0.5 mm). Sensitivity results differ less than 1% for a 250–750 keV energy window. Simulated and measured count rates agree well within a wide range of activities, including under electronic saturation of the system (the measured peak of total coincidences, for the mouse-sized phantom, was 250.8 kcps reached at 0.95 MBq mL−1 and the simulated peak was 247.1 kcps at 0.87 MBq mL−1). Agreement better than 3% was obtained in the scatter fraction comparison study. We also measured and simulated a mini-Derenzo phantom obtaining images with similar quality using iterative reconstruction methods. We concluded that the overall performance of the simulation showed good agreement with the measured results and validates the GAMOS package for PET applications. Furthermore, its ease of use and flexibility recommends it as an excellent tool to optimize design features or image reconstruction techniques

A new insight for monitoring ungulates : density surface modelling of roe deer in a Mediterranean habitat

We would like to thank the University of Aveiro (Department of Biology) and FCT/MEC for the financial support to CESAM RU (UID/AMB/50017) through national funds and, where applicable, co-financed by the FEDER, within the PT2020 Partnership Agreement. TAM is partially funded by FCT, Fundação para a Ciência e a Tecnologia, Portugal, through the project UID/MAT/00006/2013.Ungulates are especially difficult to monitor, and population estimates are challenging to obtain; nevertheless, such information is fundamental for effective management. This is particularly important for expanding species such as roe deer (Capreolus capreolus), whose populations dramatically increased in number and geographic distribution over the last decades. In an attempt to follow population trends and assess species ecology, important methodological advances were recently achieved by combining line or point sampling with geographic information systems (GIS). In this study, we combined density surface modelling (DSM) with line transect survey to predict roe deer density in northeastern Portugal. This was based on modelling pellet group counts as a function of environmental factors while taking into account the probability of detecting pellets and conversion factors to relate pellet density to animal density. We estimated a global density of 3.01 animals/100 ha (95 % CI 0.37–3.51) with a 32.82 % CV. Roe deer densities increased with increasing distance to roads as well as with higher percentage of cover areas and decreased with increasing distance to human populations. This recently developed spatial method can be advantageous to predict density over space through the identification of key factors influencing species abundance. Furthermore, surface maps for subset areas will enable to visually depict abundance distribution of wild populations. This will enable the assessment of areas where ungulate impacts should be minimized, allowing an adaptive management through time.PostprintPeer reviewe