995 resultados para Plants reproduction


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XX Symposium of Brazilian Medicinal Plants & X International Congress of Ethnopharmacology. S. Paulo, Brasil.

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The method, site, and stage of multiplication of Trypanosoma (Herpetosoma) rangeli Tejera, 1920 has not hitherto been known. "We have now observed many intracellular nests or pseudocysts, containing amastigotes and trypomastigotes of this parasite in the heart, liver, and spleen of suckling (5.0 g) male white mice (NMRI strain) inoculated i.p. with 9 x 10(4) metatrypomastigotes/g body weight from a 12-day-old culture of the "Dog-82" strain of T. rangeli. At the peak of parasitemia (1.9 x 10(6) trypomastigotes/ml blood, 3 days post-inoculation) various tissues were taken for sectioning and staining. The heart was most intensely parasitized. The amastigotes were rounded or ellipsoidal, with a rounded nucleus and the kinetoplast in the form of a straight or curved bar; the average maximum diameter of 50 measured amastigotes was 4.2 p. Binary fission was seen in the nucleus and kinetoplast of some amastigotes; no blood trypomastigotes were seen in division. The above characteristics, as well as the location of the pseudocysts in the tissues, are similar to T. cruzi. Comparison of these results with those reported for other Herpetosoma suggest study of the taxonomic position of T. rangeli.

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Over the past few decades there has been some discussion concerning the increase of the natural background radiation originated by coal-fired power plants, due to the uranium and thorium content present in combustion ashes. The radioactive decay products of uranium and thorium, such as radium, radon, polonium, bismuth and lead, are also released in addition to a significant amount of 40K. Since the measurement of radioactive elements released by the gaseous emissions of coal power plants is not compulsory, there is a gap of information concerning this situation. Consequently, the prediction of dispersion and mobility of these elements in the environment, after their release, is based on limited data and the radiological impact from the exposure to these radioactive elements is unknown. This paper describes the methodology that is being developed to assess the radiological impact due to the raise in the natural background radiation level originated by the release and dispersion of the emitted radionuclides. The current investigation is part of a research project that is undergoing in the vicinity of Sines coal-fired power plant (south of Portugal) until 2013. Data from preliminary stages are already available and possible of interpretation.

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Certain materials used and produced in a wide range of non-nuclear industries contain enhanced activity concentrations of natural radionuclides. In particular, electricity production from coal is one of the major sources of increased human exposure to naturally occurring radioactive materials. A methodology was developed to assess the radiological impact due to natural radiation background. The developed research was applied to a specific case study, the Sines coal-fired power plant, located in the southwest coastline of Portugal. Gamma radiation measurements were carried out with two different instruments: a sodium iodide scintillation detector counter (SPP2 NF, Saphymo) and a gamma ray spectrometer with energy discrimination (Falcon 5000, Canberra). Two circular survey areas were defined within 20 km of the power plant. Forty relevant measurements points were established within the sampling area: 15 urban and 25 suburban locations. Additionally, ten more measurements points were defined, mostly at the 20-km area. The registered gamma radiation varies from 20 to 98.33 counts per seconds (c.p.s.) corresponding to an external gamma exposure rate variable between 87.70 and 431.19 nGy/h. The highest values were measured at locations near the power plant and those located in an area within the 6 and 20 km from the stacks. In situ gamma radiation measurements with energy discrimination identified natural emitting nuclides as well as their decay products (Pb-212, Pb-2142, Ra-226, Th-232, Ac-228, Th-234, Pa-234, U- 235, etc.). According to the results, an influence from the stacks emissions has been identified both qualitatively and quantitatively. The developed methodology accomplished the lack of data in what concerns to radiation rate in the vicinity of Sines coal-fired power plant and consequently the resulting exposure to the nearby population.

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This research aims at analysing the mechanical performance of concrete with recycled aggregates (RA) from construction and demolition waste (CDW) from various locations in Portugal. First the characteristics of the various aggregates (natural and recycled) used in the production of concrete were thoroughly analysed. The composition of the RA was determined and several physical and chemical tests of the aggregates were performed. In order to evaluate the mechanical performance of concrete, compressive strength (in cubes and cylinders), splitting tensile strength, modulus of elasticity and abrasion resistance tests were performed. Concrete mixes with RA from CDW from several recycling plants were evaluated, in order to understand the influence that the RA's collection point, and consequently their composition, has on the characteristics of the mixes produced. The analysis of the mechanical performance allowed concluding that the use of RA worsens most of the properties tested, especially when fine RA are used. On the other hand, there was an increase in abrasion resistance when coarse RA were used. In global terms, the use of this type of aggregates, in limited contents, is viable from a mechanical viewpoint. (C) 2015 Elsevier Ltd. All rights reserved.

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The section at Cristo Rei shows sandy beds with intercalated clayey lenses (IVb division from the Lisbon Miocene series) that correspond to a major regression event dated from between ca. 17.6 and 17 Ma. They also correspond to a distal position (relatively to the typical fluviatile facies in Lisbon), nearer the basin's axis. Geologic data and paleontological analysis (plant fossils, fishes, crocodilians, land mammals) allow the reconstruction of environments that were represented in the concerned area: estuary with channels and ox-bows; upstream, areas occupied by brackish waters where Gryphaea griphoides banks developped; still farther upstream, freshwaters sided by humid forests and low mountain subtropical forests under warm temperate and rainy conditions, as well as not far away, seasonally dry environments (low density tree or shrub cover, or steppe).

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Coal contains trace elements and naturally occurring radionuclides such as 40K, 232Th, 238U. When coal is burned, minerals, including most of the radionuclides, do not burn and concentrate in the ash several times in comparison with their content in coal. Usually, a small fraction of the fly ash produced (2-5%) is released into the atmosphere. The activities released depend on many factors (concentration in coal, ash content and inorganic matter of the coal, combustion temperature, ratio between bottom and fly ash, filtering system). Therefore, marked differences should be expected between the by-products produced and the amount of activity discharged (per unit of energy produced) from different coal-fired power plants. In fact, the effects of these releases on the environment due to ground deposition have been received some attention but the results from these studies are not unanimous and cannot be understood as a generic conclusion for all coal-fired power plants. In this study, the dispersion modelling of natural radionuclides was carried out to assess the impact of continuous atmospheric releases from a selected coal plant. The natural radioactivity of the coal and the fly ash were measured and the dispersion was modelled by a Gaussian plume estimating the activity concentration at different heights up to a distance of 20 km in several wind directions. External and internal doses (inhalation and ingestion) and the resulting risk were calculated for the population living within 20 km from the coal plant. In average, the effective dose is lower than the ICRP’s limit and the risk is lower than the U.S. EPA’s limit. Therefore, in this situation, the considered exposure does not pose any risk. However, when considering the dispersion in the prevailing wind direction, these values are significant due to an increase of 232Th and 226Ra concentrations in 75% and 44%, respectively.

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The aim of this work was to simulate the radionuclides dispersion in the surrounding area of a coal-fired power plant, operational during the last 25 years. The dispersion of natural radionuclides (236Ra, 232Th and 40K) was simulated by a Gaussian plume dispersion model with three different stability classes estimating the radionuclides concentration at ground level. Measurements of the environmen-tal activity concentrations were carried out by γ-spectrometry and compared with results from the air dispersion and deposition model which showed that the stabil-ity class D causes the dispersion to longer distances up to 20 km from the stacks.

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The concerns on metals in urban wastewater treatment plants (WWTPs) are mainly related to its contents in discharges to environment, namely in the final effluent and in the sludge produced. In the near future, more restrictive limits will be imposed to final effluents, due to the recent guidelines of the European Water Framework Directive (EUWFD). Concerning the sludge, at least seven metals (Cd, Cr, Cu, Hg, Ni, Pb and Zn) have been regulated in different countries, four of which were classified by EUWFD as priority substances and two of which were also classified as hazardous substances. Although WWTPs are not designed to remove metals, the study of metals behaviour in these systems is a crucial issue to develop predictive models that can help more effectively the regulation of pre-treatment requirements and contribute to optimize the systems to get more acceptable metal concentrations in its discharges. Relevant data have been published in the literature in recent decades concerning the occurrence/fate/behaviour of metals in WWTPs. However, the information is dispersed and not standardized in terms of parameters for comparing results. This work provides a critical review on this issue through a careful systematization, in tables and graphs, of the results reported in the literature, which allows its comparison and so its analysis, in order to conclude about the state of the art in this field. A summary of the main consensus, divergences and constraints found, as well as some recommendations, is presented as conclusions, aiming to contribute to a more concerted action of future research. © 2015, Islamic Azad University (IAU).

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The objective of this research is the production of concrete with recycled aggregates (RA) from various CDW plants around Portugal. The influence of the RA collection location and consequently of their composition on the characteristics of the concrete produced was analysed. In the mixes produced in this research RA from five plants (Valnor, Vimajas, Ambilei, Europontal and Retria) were used: in three of them coarse and fine RA were analysed and in the remaining ones only coarse RA were used. The experimental campaign comprised two tests in fresh concrete (cone of Abrams slump and density) and eight in hardened concrete (compressive strength in cubes and cylinders, splitting tensile strength, modulus of elasticity, water absorption by immersion and capillarity, carbonation and chloride penetration resistance). It was found that the use of RA causes a quality decrease in concrete. However, there was a wide results scatter according to the plant where the RAs were collected, because of the variation in composition of the RA. It was also found that the use of fine RA causes a more significant performance loss of the concrete properties analysed than the use of coarse RA. © (2015) Trans Tech Publications, Switzerland.

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Dissertação apresentada para obtenção do Grau de Doutor em Sistemas de Informação Industriais, Engenharia Electrotécnica, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia

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Dissertation presented to obtain the degree of Doctorate in Biochemistry by Instituto de Tecnologia Química e Biológica of Universidade Nova de Lisboa

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A thesis submitted in fulfilment of the requirements for the Degree of Doctor of Philosophy in Sanitary Engineering in the Faculty of Sciences and Technology of the New University of Lisbon

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Leishmanias can be produced by inoculation in conditioned McCoy cell culture growth medium (CGM). Leishmania (Leishmania) infantum chagasi (100 parasites) grown in NNN medium was inoculated in 2.5 mL CGM, kept in plates (24 wells) and its multiplication was observed for five days (120 hours). After day 5, the medium was saturated with the flagellate forms of the parasite (promastigotes). The reproduction of the leishmanias was observed every 24 hours and the number of parasites was calculated by counting the parasites in a drop of 10 µ L and photomicrographied. So the number of Leishmanias was adjusted to 1 mL volume. The advantage of the technique by isolation of Leishmania in CGM demonstrated in this study is its low cost and high efficacy even with a small quantity of parasites (10² promastigotes) used as inoculum. Additionally, isolation of the leishmania can be obtained together with an increase in their density (180 times) as observed by growth kinetics, within a shorter time. These results justify the use of this low-cost technique for the isolation and investigation of the behavior and multiplication of Leishmania both in vertebrates and invertebrates, besides offering means of obtaining antigens, whether whole antigens (leishmanias) or the soluble antigens produced by the parasites which may be useful for the production of new diagnostic kits.

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Cation transporters/channels are key players in a wide range of physiological functions in plants, including cell signaling, osmoregulation, plant nutrition and metal tolerance. The recent identification of genes encoding some of these transport systems has allowed new studies toward further understanding of their integrated roles in plant. This review summarizes recent discoveries regarding the function and regulation of the multiple systems involved in cation transport in plant cells. The role of membrane transport in the uptake, distribution and accumulation of cations in plant tissues, cell types and subcellular compartments is described. We also discuss how the knowledge of inter- and intra-species variation in cation uptake, transport and accumulation as well as the molecular mechanisms responsible for these processes can be used to increase nutrient phytoavailability and nutrients accumulation in the edible tissues of plants. The main trends for future research in the field of biofortification are proposed.