33 research outputs found

    Low temperature degradation behaviour of 10Ce-TZP/Al2O3 bioceramics obtained by microwave sintering technology

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    Zirconia is one of the most used ceramics, especially for biomedical applications, due to its exceptional mechanical properties. However, it is commonly known that its properties can be diminished owing to a low temperature degradation (LTD). This phenomenon consists on a spontaneous phase transformation, from tetragonal to monoclinic, under certain conditions, which is accelerated when the samples are exposed under high levels of humidity at a temperature range between 20-300 ºC. In addition to the fact that the monoclinic phase presents worse mechanical properties than the tetragonal one, there is a volume change of 4% between phases that gives rise to defects in the material as microcracks. Due to this reason, zirconia prostheses failed catastrophically inside the human body between 1999 and 2001 (1). Previous researches reveal that Al2O3 addition suppress the propagation of phase transformation (2). Thus, the aim of the present work is to study the hydrothermal ageing of zirconia doped with ceria and toughened with alumina (10Ce-TZP/Al2O3) composite, which has been sintered by microwave employing two different frequencies: 2.45 and 5.8 GHz. Microwave heating technology is based on the absorption of electromagnetic radiation by the material, which allows the sample to be heated. So far, most microwave heating equipments use 2.45 GHz; accordingly, the novelty of this study is to employ a frequency of 5.8 GHz and to investigate its effect on LTD. LTD is carried out in an autoclaved in steam at 120 ºC and 1.2 bar, because these conditions accelerate the hydrothermal aging process (3). In order to characterize the degraded samples, micro-Raman spectroscopy, AFM, nanoindentation technique and electronic microscopy have been performed. References 1. Norton, M. R., Yarlagadda, R., Anderson, G. H. J. Bone Joint Surg. Br., 2002, 84–B, 631–635. 2. Fabbri, P., Piconi, C., Burresi, E., Magnani, G., Mazzanti, F., Mingazzini, C. Dent. Mater., 2014. 3. Presenda, Á., Salvador, M. D., Moreno, R., Borrell, A. J. Am. Ceram. Soc., 2015, 98, 3680–3689

    Valor documental de los herbarios históricos : aportación de la exsiccata Flora Forestal Española al conocimiento de las cubiertas forestales de las provincias de Huelva y Sevilla (España)

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    Los herbarios, además de información botánica, pueden contener datos históricos de valor científico para el estudio de los montes y de su historia, como los recogidos en las colecciones de material que fue recolectado para la descripción y cartografía de las cubiertas forestales españolas. En este trabajo se sintetizan los datos obtenidos de la exsiccata Flora Forestal Española creada por investigadores del Instituto Forestal de Investigaciones y Experiencias-IFIE que, junto con información obtenida de documentos inéditos, evidencian la vinculación de esta colección a la realización de los mapas forestales y estudios de flora y vegetación provinciales; en particular a los de las provincias de Huelva y Sevilla, que quedaron inéditos, permitiendo precisar mejor su datación y aportando datos botánicos relevantes e información sobre el paisaje forestal anterior a las grandes repoblaciones con pinos y eucaliptos realizadas en el suroeste peninsular

    The effect of perceived discrimination on the health of immigrant workers in Spain

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    Background: Discrimination is an important determinant of health inequalities, and immigrants may be more vulnerable to certain types of discrimination than the native-born. This study analyses the relationship between immigrants' perceived discrimination and various self-reported health indicators. Methods: A cross-sectional survey was conducted (2008) amongst a non-random sample of 2434 immigrants from Ecuador, Morocco, Romania and Colombia in four Spanish cities: Barcelona, Huelva, Madrid and Valencia. A factorial analysis of variables revealed three dimensions of perceived discrimination (due to immigrant status, due to physical appearance, and workplace-related). The association of these dimensions with self-rated health, mental health (GHQ-12), change in self-rated health between origin and host country, and other self-reported health outcomes was analysed. Logistic regression was used adjusting for potential confounders (aOR-95%CI). Subjects with worsening self-reported health status potentially attributable to perceived discrimination was estimated (population attributable proportion, PAP %). Results: 73.3% of men and 69.3% of women immigrants reported discrimination due to immigrant status. Moroccans showed the highest prevalence of perceived discrimination. Immigrants reporting discrimination were at significantly higher risk of reporting health problems than those not reporting discrimination. Workplace-related discrimination was associated with poor mental health (aOR 2.97 95%CI 2.45-3.60), and the worsening of self-rated health (aOR 2.20 95%CI 1.73- 2.80). 40% (95% CI 24-53) PAP of those reporting worse self-rated health could be attributable to discrimination due to immigrant status. Conclusions: Discrimination may constitute a risk factor for health in immigrant workers in Spain and could explain some health inequalities among immigrant populations in Spanish society.This work was supported by the following sources: Carolina Foundation (Spain), Healthcare Research Fund of the Spanish Ministry of Health and Consumption (references PI050497, PI052202, PI052334, PI061701, and PI0790470

    Contribución de la Paleofitogeografía a la interpretación del paisaje vegetal ibérico: estado de conocimientos y nuevas perspectivas de investigación

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    The palaeobotanical studies that have been accomplished in the Iberian Peninsula during the last two decades have provided a great amount of data that can be applied in geobotanical knowledge. In most of the cases, those results have contributed to solve classical scientific debates regarding vegetal landscapes interpretations. One of the most relevant discussions is related to the aloctonous or non-aloctonous origin of much of the Iberian pine forests, on diverse Iberian habitats. The main contributions of Palaeobotany to the processes that explain the present distribution of plants are reviewed in a spatial and temporal framework, from old geological periods (Mesozoic, Tertiary) to the recent ones (Pleistocene, Holocene). Linked to the history of our vegetal landscapes, Pleistocene and Holocene epochs have been treated from two different points of view: firstly the problems within extensive territorial environments and, secondly, the problems related to the interpretation of the evolution and/or behaviour of taxa. In the last part, some new investigation trends related to palaeophytogeography are exposed, focusing on the high potential interest on being applied to Iberian ecosystems.Los trabajos de carácter paleobotánico realizados en la península Ibérica en las dos últimas décadas han proporcionado un importante volumen de resultados con aplicación en el ámbito del conocimiento geobotánico. En muchos casos, esos resultados han aportado soluciones a debates clásicos relativos a la interpretación del paisaje vegetal. Uno de los más conocidos es el de la consideración, como espontáneos o no, de muchos de los pinares ibéricos en diferentes ámbitos del territorio peninsular. Se revisan las contribuciones más importantes de la Paleobotánica a los procesos que explican la actual distribución de las plantas, en un marco tanto espacial como temporal, desde periodos geológicos antiguos (Mesozoico, Terciario) a los más recientes (Pleistoceno, Holoceno). Dentro de estos últimos nos hemos referido, por una parte, a problemas planteados en ámbitos territoriales extensos y, por otra, a problemas vinculados a la interpretación de la evolución y/o comportamiento de taxones concretos. Por último se hace referencia a las tendencias recientes y nuevas metodologías de aplicación en paleofitogeografía, aludiendo a los primeros resultados que hayan podido proporcionar en el marco peninsular

    The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats

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    The Mediterranean Sea is a marine biodiversity hot spot. Here we combined an extensive literature analysis with expert opinions to update publicly available estimates of major taxa in this marine ecosystem and to revise and update several species lists. We also assessed overall spatial and temporal patterns of species diversity and identified major changes and threats. Our results listed approximately 17,000 marine species occurring in the Mediterranean Sea. However, our estimates of marine diversity are still incomplete as yet—undescribed species will be added in the future. Diversity for microbes is substantially underestimated, and the deep-sea areas and portions of the southern and eastern region are still poorly known. In addition, the invasion of alien species is a crucial factor that will continue to change the biodiversity of the Mediterranean, mainly in its eastern basin that can spread rapidly northwards and westwards due to the warming of the Mediterranean Sea. Spatial patterns showed a general decrease in biodiversity from northwestern to southeastern regions following a gradient of production, with some exceptions and caution due to gaps in our knowledge of the biota along the southern and eastern rims. Biodiversity was also generally higher in coastal areas and continental shelves, and decreases with depth. Temporal trends indicated that overexploitation and habitat loss have been the main human drivers of historical changes in biodiversity. At present, habitat loss and degradation, followed by fishing impacts, pollution, climate change, eutrophication, and the establishment of alien species are the most important threats and affect the greatest number of taxonomic groups. All these impacts are expected to grow in importance in the future, especially climate change and habitat degradation. The spatial identification of hot spots highlighted the ecological importance of most of the western Mediterranean shelves (and in particular, the Strait of Gibraltar and the adjacent Alboran Sea), western African coast, the Adriatic, and the Aegean Sea, which show high concentrations of endangered, threatened, or vulnerable species. The Levantine Basin, severely impacted by the invasion of species, is endangered as well

    Perceived sexism as a health determinant in Spain

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    OBJECTIVES: The goals of the present study are to explore the association between perceived sexism and self-perceived health, health-related behaviors, and unmet medical care needs among women in Spain; to analyze whether higher levels of discrimination are associated with higher prevalence of poor health indicators and to examine whether these relationships are modified by country of origin and social class. MATERIALS AND METHODS: The study is based on a cross-sectional design using data from the 2006 Spanish Health Interview Survey. We included women aged 20-64 years (n = 10,927). Six dependent variables were examined: four of health (self-perceived health, mental health, hypertension, and having had an injury during the previous year), one health behavior (smoking), and another related to the use of the health services (unmet need for medical care). Perceived sexism was the main independent variable. Social class and country of origin were considered as effect modifiers. We obtained the prevalence of perceived sexism. Logistic regression models, adjusted for potential confounders, were fitted to study the association between sexism and poor health outcomes. Results: The prevalence of perceived sexism was 3.4%. Perceived sexism showed positive and consistent associations with four poor health outcomes (poor self-perceived health, poor mental health, injuries in the last 12 months, and smoking). The strength of these associations increased with increased scores for perceived sexism, and the patterns were found to be modified by country of origin and social class. CONCLUSION: This study shows a consistent association between perceived sexism and poor health outcomes in a country of southern Europe with a strong patriarchal tradition.This study was partially funded by CIBER Epidemiología y Salud Pública, Spain; by the Ministerio de Sanidad y Consumo—Observatorio de Salud de la Mujer, Dirección General de la Agencia de Calidad—y Ministerio de Ciencia e Innovación—Instituto de Salud Carlos III, Spain; and by the project "Analysis of the Effects of Discrimination in the Self-perceived Health in Adult and Children Populations in Spain" from the Fondo de Investigación Sanitaria of the latter institutions (reference PI080782)

    Effect of frequency on MW assisted sintering: 2.45 GHz versus 5.8 GHz

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    Innovative non-conventional approaches, such as microwave sintering, are being developed as a method for sintering a variety of materials which shown advantages over conventional sintering procedures. This work involves an investigation of the microwave sintering of an ATZ composite with two different microwave applicators and frequency generators: 2.45 GHz and 5.8 GHz. Zirconia doped with ceria and toughened with alumina (10Ce-TZP/Al2O3) is the composite used in this study. The samples were sintered by microwave in air at 1200 and 1300 \ub0C with 10 min of dwell time at 2.45 and 5.8 GHz in order to evaluate their effects on sintering, using an optimized experimental configuration. In addition, the mechanical properties of MW-sintered samples were compared with those obtained for the same composites sintered by the conventional method (1500 \ub0C/120 min), such as relative density, hardness and fracture toughness

    Periodontal outcomes and social, racial and gender inequalities in Brazil: a systematic review of the literature between 1999 and 2008 Condições periodontais e desigualdades sociais, raciais e de gênero no Brasil: revisão sistemática da literatura do período de 1999 a 2008

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    The objective of this study was to review the Brazilian epidemiologic literature on periodontal outcomes and socio-demographic factors, assessing bibliographic and methodological characteristics of this scientific production, as well as the consistency and statistical significance of the examined associations. A systematic review was carried out in six bibliographic sources. The review was limited to the period between 1999 and 2008, without any other type of restriction. Among the 410 papers identified, 29 were included in the review. An increasing number of articles, specifically in the last four years of study, was observed. However, there is a concentration of studies in the South and Southeast regions of Brazil, and many of them are not closely connected to theoretical formulations in the field. In spite of these shortcomings, the review findings corroborate the idea that poor socioeconomic conditions are associated with periodontal outcomes, as demonstrated primarily by income and schooling indicators.<br>O objetivo deste trabalho foi revisar a literatura epidemiológica brasileira sobre condições periodontais e aspectos sociodemográficos, avaliando características bibliográficas e metodológicas dessa produção, bem como a consistência e a significância estatística das associações examinadas. Foi conduzida uma revisão sistemática, por meio de consulta eletrônica, a seis fontes bibliográficas. A revisão foi restrita ao período de 1999 a 2008, sem a imposição de quaisquer outros limites de pesquisa. Entre os 410 artigos identificados, 29 foram incluídos na revisão. Observa-se crescimento da produção, especialmente no último quadriênio. Entretanto, há uma concentração dos estudos nas regiões Sul e Sudeste do país, e os trabalhos não se apoiam explicitamente em elaborações teóricas pertinentes ao tema. Apesar dessas limitações, os resultados dessa revisão sugerem que há uma relação inversa entre indicadores socioeconômicos e desfechos periodontais, demonstrada especialmente por indicadores de renda e escolaridade
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