Physiological and anatomical characteristics of leaves of two clones of guarana

The objective of this work was to analyze gas exchange, photosynthetic characteristics, photochemical efficiency of photosystem II and anatomical characteristics of young plant leaves of two guarana (Paullinia cupana) clones (BRS-CG372RC and BRS-CG611RL) growing under open field. The variables of gas exchange and fluorescence of chlorophyll a were evaluated in mature leaves. The values of photosynthesis and transpiration found for BRS-CG372RC were 27% greater and 80% lesser than values found for BRS-CG611RL, respectively. The values of stomatal conductance found for the clones BRS-CG372RC and BRS-CG611RL were in the order of 224 and 614 mmol mm-2 s-1, respectively. The values of photorespiration, rate of carboxylation and rate electron transport were greater in BRS-CG372RC. The clone BRS-CG372RC exhibited stomatal density 26% greater than BRS-CG611RL. However, the area of ostiolar opening was 42% greater in BRS-CG611RL. The values of the water use efficiency in BRS-CG372RC were 134% greater than in BRS-CG611RL. High stomatal density and low stomatal conductance can be important characteristics in the selection of the clones with a good ability to assimilate carbon and optimize the use of water

Características fisiológicas e anatômicas de folhas de dois clones de guaraná

The objective of this work was to analyze gas exchange, photosynthetic characteristics, photochemical efficiency of photosystem II and anatomical characteristics of young plant leaves of two guarana (Paullinia cupana) clones (BRS-CG372RC and BRS-CG611RL) growing under open field. The variables of gas exchange and fluorescence of chlorophyll a were evaluated in mature leaves. The values of photosynthesis and transpiration found for BRS-CG372RC were 27% greater and 80% lesser than values found for BRS-CG611RL, respectively. The values of stomatal conductance found for the clones BRS-CG372RC and BRS-CG611RL were in the order of 224 and 614 mmol mm-2 s-1, respectively. The values of photorespiration, rate of carboxylation and rate electron transport were greater in BRS-CG372RC. The clone BRS-CG372RC exhibited stomatal density 26% greater than BRS-CG611RL. However, the area of ostiolar opening was 42% greater in BRS-CG611RL. The values of the water use efficiency in BRS-CG372RC were 134% greater than in BRS-CG611RL. High stomatal density and low stomatal conductance can be important characteristics in the selection of the clones with a good ability to assimilate carbon and optimize the use of water.O objetivo deste trabalho foi analisar as trocas gasosas, as características fotossintéticas, a eficiência fotoquímica do fotossistema II e as características anatômicas foliares de plantas jovens de dois clones de guaraná desenvolvidas a pleno sol. As variáveis de trocas gasosas e fluorescência da clorofila a foram determinadas em folhas maduras. Os valores de fotossíntese e transpiração encontrados para BRS-CG372RC foram 27% maiores e 80% menores que os valores encontrados para BRS-CG611RL, respectivamente. Os valores de condutância estomática dos clones BRS-CG372RC e BRS-CG611RL foram de aproximadamente 224 e 614 mmol m-2 s-1, respectivamente. Os valores de fotorrespiração, taxa de carboxilação e taxa de transporte de elétrons foram maiores em BRS-CG372RC. O clone BRS-CG372RC apresentou densidade estomática 26% maior que BRS-CG611RL. A área de abertura do ostíolo foi 42% maior em BRS-CG611RL. O valor da eficiência no uso da água em BRS-CG372RC foi 134% maior que em BRS-CG611RL. Alta densidade estomática e baixa condutância estomática são características importantes para a seleção de clones com boa capacidade para assimilar carbono e que sejam eficientes no uso da água

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Agricultural land use change and associated driving forces over the past 180 years in two municipalities of the Brazilian Cerrado

This paper aims to test the hypothesis that a single driving force from the local, national, or global level is capable of triggering land use changes, including large scale deforestation, within a historical context. To reach this goal we describe and explain the driving forces from the global to farm level that have shaped agricultural land uses, as a case study, over 180 years in the municipalities of Quirinópolis and Gouvelândia in the Brazilian Cerrado. Through secondary data, field surveys, and interviews with farmers and other stakeholders involved with agricultural production, we identified four distinct periods in which drastic or little land use occurred. The evidence found supports our hypothesis. Two drastic land use changes occurred in Quirinópolis and Gouvelândia. The first one was the replacement of about 400,000 ha of original vegetation by pastures and crops between 1965 and 1985 triggered by the availability of abundant subsidized rural credits for farmers; the second one was initiated in 2005 with the replacement of 100,000 ha of pastures and cropping area by sugarcane, which was driven by the sudden domestic and world demand for sugar and ethanol

Agricultural land use change and associated driving forces over the past 180 years in two municipalities of the Brazilian Cerrado

This paper aims to test the hypothesis that a single driving force from the local, national, or global level is capable of triggering land use changes, including large scale deforestation, within a historical context. To reach this goal we describe and explain the driving forces from the global to farm level that have shaped agricultural land uses, as a case study, over 180 years in the municipalities of Quirinópolis and Gouvelândia in the Brazilian Cerrado. Through secondary data, field surveys, and interviews with farmers and other stakeholders involved with agricultural production, we identified four distinct periods in which drastic or little land use occurred. The evidence found supports our hypothesis. Two drastic land use changes occurred in Quirinópolis and Gouvelândia. The first one was the replacement of about 400,000 ha of original vegetation by pastures and crops between 1965 and 1985 triggered by the availability of abundant subsidized rural credits for farmers; the second one was initiated in 2005 with the replacement of 100,000 ha of pastures and cropping area by sugarcane, which was driven by the sudden domestic and world demand for sugar and ethanol

Zircônia: desafio do processo de tratamento de superfície

Introdution: Dental ceramics have been used as restorative materials since 1770 for presenting aesthetic properties similar to natural teeth. The search for procedures that aim to increase the adhesion between zirconia, a polycrystalline ceramic, and a cementing agent, is a challenge and has stimulated the development of several studies. Objective: The objective of this study is to discuss the different types of recommended surface treatments for yttria stabilized zirconia (Y-TZP), as well as the advantages and disadvantages described in the literature. Materials and methods: The present study is a literature review carried out of scientific articles published between 2003 and 2019, indexed in the MEDLINE, PubMed and Scielo databases. The following search terms were used: “zirconia surface treatment”, “Y-TZP surface treatment”, “zirconia cementing agent”, “Y-TZP cementing agent”, “zirconia adhesion” and “adhesion to zirconia Y-TZP”. Results: 413 articles were found that met at least one of the registered inclusion criteria. However, data from a total of 69 articles were used that met all the inclusion criteria. Conclusion: The reported surface treatment protocols still have limitations regarding the long-term behavior of bond strength. However, when the characteristics of the preparation are not favorable to retention, blasting with Al2O3 particles coated with silica (30μm) should be used, being less aggressive to ceramic than other blasting protocols described. As for the cementing agent, it is always recommended to use resin cements that have MDP in their composition, since they provide stable chemical bonds and long-lasting adhesive behavior.Introdução: As cerâmicas odontológicas têm sido utilizadas como materiais restauradores desde 1770 por apresentarem propriedades estéticas semelhantes aos dentes naturais. A busca por procedimentos que visem aumentar a adesão entre zircônia, uma cerâmica policristalina, e agente cimentante, é um desafio e tem estimulado o desenvolvimento de diversos estudos. Objetivo: O objetivo deste estudo é discutir os diferentes tipos de tratamentos de superfície preconizados para zircônia estabilizada com ítria (Y-TZP), bem como as vantagens e desvantagens descritas na literatura. Materiais e métodos: O presente estudo trata-se de uma revisão de literatura realizada de artigos científicos publicados entre 2003 e 2019, indexados nas bases de dados MEDLINE, PubMed e Scielo. Foram utilizados os seguintes termos de pesquisa: “tratamento de superfície da zircônia”, “tratamento de superfície Y-TZP”, “agente cimentante para zircônia”, “agente cimentante para Y-TZP”, “adesão à zircônia” e “adesão à Y-TZP”. Resultados: Foram encontrados 413 artigos que contemplavam pelo menos um dos critérios de inclusão registrados. No entanto, foram utilizados os dados de um total de 69 artigos que contemplavam todos os critérios de inclusão. Conclusão: Os protocolos de tratamento de superfície relatados ainda apresentam limitações quanto ao comportamento de longo prazo da resistência de união. No entanto, quando as características do preparo não são favoráveis à retenção, o jateamento com partículas de Al2O3 revestidas com sílica (30μm) deve ser utilizado, sendo menos agressivo à cerâmica que outros protocolos de jateamento descritos. Quanto ao agente cimentante, recomenda-se sempre o uso de cimentos resinosos que apresentem MDP em sua composição, uma vez que proporcionam ligações químicas estáveis e comportamento adesivo duradouro