2,660 research outputs found
Growth performance, carcass traits and pork quality of pigs fed ractopamine and slaughtered between 100 and 145 kg.
Natural attenuation processes in AMD context by mineralogical control: iron oxyhydroxides, oxyhydroxysulfates, and efflorescent sulfates
Acid mine drainage (AMD) is a common problem associated with the weathering of metal sulfide
wastes in abandoned mining areas, which can be rich in toxic metals and metalloids. Oxidative dissolution
of these minerals may negatively affect the soils and water reservoirs nearby. The formation of secondary
mineral phases such as iron oxyhydroxides, oxyhydroxysulfates, and efflorescent sulfates may be a natural
attenuation process in these areas because these minerals can scavenge potentially toxic elements. Typically
formed by the evaporation (efflorescent salts) or precipitation (ochreous iron-rich oxyhydroxides) these
minerals are highly soluble and reactive. Therefore, their characterization and inventory are particularly
important for predicting the cycles of retention/contamination or accumulation zones of potential toxic
elements (PTE) and acidity in mining contaminated systems.
The abandoned mines of Valdarcas and São Domingos were selected for the present study due to
their AMD signature and occurrence of some of these secondary minerals. Valdarcas (north of Portugal) is
a W-mine associated with a skarn deposit with sulfides that has already been rehabilitated. However, the
AMD problems remain in the watercourse that receives leachates from the waste dumps. São Domingos is
a Cu-mine composed of massive sulfide deposits that belong to the Iberian Pyrite Belt (south of Portugal).
This mining area, which is presently under remediation process, is highly contaminated and AMD is a longlasting problem. The samples collected in these mining areas were characterized by their morphology, size,
mineralogy, and chemical composition using different techniques: binocular microscopy, SEM-EDS, TEM,
BET, DRX, FTIR, and XPS.
In Valdarcas mine area, typical ochreous phases such as schwertmannite and goethite were
identified as the dominant secondary phases. These brownish-yellow ferric amorphous and poorly
crystalline minerals with high surface area (125 mg2
/m) can remove PTE via adsorption processes,
contributing to their retention in the mining environment. In contrast, at São Domingos, efflorescent sulfate
salts are more abundant. Melanterite and copiapite were the prevailing salts identified. With different
morphologies, these minerals are highly soluble and therefore play a relevant key in the
retention/mobilization cycles of hazardous contaminants, such as arsenic (As).
This integrative methodologic approach, based on the use of several techniques, allowed a
complete characterization of these minerals. In addition to composition, the surface properties that are
relevant for the adsorption ability, were also obtained. Therefore, the study revealed a diversity of behaviors
for the identified phases, suggesting various roles in increasing the resilience of the contaminated systems
THE DETERMINATION OF DRAG IN THE GLIDING PHASE IN SWIMMING
The hydrodynamic drag forces produced by the swimmer during the sub aquatic gliding have been analyzed appealing to experimental investigation methods (e.g., Lyttle et al., 2000). However, the obtained results varied, which can translate some of the main inherent difficulties involved in the experimental studies. Thus, through application of a numerical method of Computational Fluid Dynamics (CFD), we intended to study the hydrodynamic drag forces, created during the displacement of the swimmer in different gliding positions, attempting to address some practical concerns to swimmers and coaches
Caracterização morfológica de sementes de variedades locais de feijoeiro comum (Phaseolus vulgaris) do Ace.
O feijoeiro comum é cultivado no Acre exclusivamente por agricultores familiares e representa grande importância agronômica, econômica, social e cultural. A abertura de novas estradas no Estado constitui-se em uma ameaça a perda da variabilidade e de espécies locais necessitando que essas seja estudadas para usos futuros. Este trabalho teve como objetivo caracterizar sementes de dez variedades locais de feijoeiro comum. Avaliaram-se 10 variedades. As sementes foram coletados em feiras e mercados públicos de municÃpios do Acre. Os trabalhos de campo e laboratório foram realizados no primeiro semestre de 2012. Foram avaliadas as seguintes caracterÃsticas; cor do tegumento, presença e cor do halo, brilho, forma e grau de achatamento da semente e o peso de 100 sementes. Detectou-se a ocorrência de variabilidade para todos os descritores de sementes avaliados, com destaque para a diversidade de cores, brilho e forma bem como para a amplitude do caráter peso de 100 sementes
CaracterÃsticas biométricas de sementes crioulas de feijoeiro comum do Acre.
O Estado do Acre possui uma grande variabilidade de variedades tradicionais de feijão comum cultivadas por agricultores familiar, ameaçadas de extinção e erosão genética. Esse recurso representa uma possibilidade de uso em melhoramento genético. Objetivou-se nesse estudo determinar a variabilidade das caracterÃsticas morfológicas de sementes de feijão comum crioulo do Acre. As variedades estudadas foram: Rosinha, Peruano amarelo, Gorgotuba vermelho, Peruano vermelho, Feijão preto, Gorgotuba branco, Enxofre; coletados em mercados públicos. As variáveis mensuradas: comprimento, largura, espessura e peso de 100 sementes; obtendo-se a amplitude, valor mÃnimo, valor máximo, média, erro padrão, variância e o desvio padrão. Para comprimento a maior amplitude e maior variância foram encontradas para o genótipo Enxofre; para largura, o genótipo Rosinha foi o de maior amplitude. Para espessura de sementes o maior valor foi apresentado por Gorgotuba branco. Há variabilidade para caracteres da semente de variedades tradicionais cultivadas no Acre
Extratos de Morinda citrifolia e Piper nigrum no controle da mancha bacteriana do maracujazeiro.
Suplemento, ref. 886. Edição dos Resumos do 45º Congresso Brasileiro de Fitopatologia, Manaus, 2012. CBFito 2012
Avaliação de espécies leguminosas na formação de cafezais no segmento da agricultura familiar no Acre.
Leguminosas quando consorciadas com o café e usadas como adubação verde podem contribuir fornecendo nitrogênio e proteção ao solo pela adição de matéria orgânica. O trabalho foi conduzido com o objetivo de avaliar o efeito do uso de leguminosas no sistema de produção de café, no segmento de agricultura familiar, visando promover a implantação e a manutenção dos cafezais de forma técnica e economicamente sustentável. O experimento foi conduzido no perÃodo de novembro de 2000 a abril de 2003, em delineamento experimental de blocos ao acaso em esquema de parcelas subdivididas, com quatro repetições. Os tratamentos utilizados nas parcelas foram as leguminosas (Stizolobium atterrimum, Cajanus cajan, Canavalia endiformis e Flemingia congesta) e a testemunha (sem leguminosa) e, nas subparcelas, duas doses de N (0 e 22 g de N por cova). A Flemingia congesta e a Mucuna aterrima foram as leguminosas que mais influenciaram positivamente a produtividade dos cafeeiros, independente da adubação nitrogenada. Em relação à testemunha, o aumento em produção foi de 109% quando utilizou-se a Flemingia congesta e 52% com a Mucuna aterrima. A Flemingia congesta foi também a leguminosa que melhor controlou as invasoras, dado o volume de fitomassa produzida e a possibilidade de 2 cortes durante um perÃodo de doze meses, evidenciando o potencial desta leguminosa na formação de novos cafezais no Acre. Por outro lado, a Canavalia ensiformis, leguminosa que é normalmente utilizada nas entrelinhas dos cafeeiros pelos cafeicultores, do Acre e de outras regiões produtoras, neste trabalho influenciou negativamente a altura das plantas, diâmetro da copa e crescimento dos cafeeiros
Anti-tumorigenic and Platinum-Sensitizing Effects of Apolipoprotein A1 and Apolipoprotein A1 Mimetic Peptides in Ovarian Cancer
Objective: Apolipoprotein A1 (ApoA1) is remarkably decreased in serum and ovarian tissues of ovarian cancer patients. ApoA1 and ApoA1 mimetic peptides can sequestrate pro-inflammatory phospholipids, some of which are known to activate a variety of oncogenic pathways. Besides, more intrinsic anti-tumorigenic properties, independent from interaction with lipids, have also been described for ApoA1. We aimed to disclose the effects of ApoA1 and a mimetic peptide on the malignant phenotype of ovarian cancer cells, particularly regarding cell viability, invasiveness and platinum sensitization. Methods: Cells viability was assessed by MTS assay. Extracellular matrix invasion was assessed by transwell and spheroid invasion assays. Western blotting was performed to evaluate the effect of test compounds on intracellular pathways. Sensitization assays were performed in vitro and in the biologically relevant in ovo chorioallantoic membrane model. Results: Both ApoA1 and the mimetic peptide, at a concentration of 100 μg/mL, were able to decrease the viability of SKOV3, CAOV3, and OVCAR3 cells (p 0.05). ApoA1 decreased SKOV3 cells invasiveness at 300 μg/mL after 72 and 96 h of exposure (p < 0.05), while the ApoA1 mimetic peptide prevented cell invasion at 50 and 100 μg/mL (p < 0.01). Treatment with 100 μg/mL of ApoA1 mimetic peptide decreased Akt phosphorylation in SKOV3 cells (p < 0.01). Accordingly, treatment with increasing concentrations of the peptide sensitized SKOV3, OVCAR3 and CAOV3 cells to cisplatin. This synergistic effect was observed both in vitro and in ovo. Conclusions: These results support the role of ApoA1 and ApoA1 mimetics as suppressors of ovarian tumorigenesis and as chemosensitising agents.publishersversionpublishe
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