40 resultados para Fossil Bivalves
Resumo:
A new fossil species of phlebotomine sandflies is described from Dominican amber based in one specimen. Pintomyia (Pifanomyia) paleotrichia sp. nov. is distinguished from the other extant and extinct species by aspects of paramere and the basal tuft of bristles in the gonocoxite.
Resumo:
Leptoconops nosopheris sp. n. (Diptera: Ceratopogonidae) is described from a blood-filled female biting midge in Early Cretaceous Burmese amber. The new species is characterized by a very elongate terminal flagellomere, elongate cerci, and an indistinct spur on the metatibia. This biting midge contained digenetic trypanosomes (Kinetoplastida: Trypanosomatidae) in its alimentary tract and salivary glands. These trypanosomes are described as Paleotrypanosoma burmanicus gen. n., sp. n., which represents the first fossil record of a Trypanosoma generic lineage.
Resumo:
This work considers mainly the problem of environmental pollution due to the production of energy by burning fossil fuels, particularly in urban vehicles. Electrochemical energy conversion is proposed as a partial solution to this problem, through the use of hydrogen in fuel cells. In both the production of hydrogen by electrolysis and in the electrochemical processes in fuel cells, the key factor is electrocatalysis. The concept of electrocatalysis, the production of catalysts and supported catalysts and their use in practical systems for the conversion of energy is discussed.
Resumo:
Adopting the perspective of human health risk assessment, an interdisciplinary research group has been investigating since 1998 the quality of mussels and oysters cultivated in coastal zones of Santa Catarina State. Evaluation of physico-chemical parameters considered relevant in measuring the degree of eutrophication showed values compatible with the dynamics of well balanced environmental systems. Concentrations of metallic and semi-metallic elements in seawater and bivalves were found to be similar to or lower than those found in Chile, Greenland and the USA. Further investigations focusing upon sediments will provide new and useful data for the management of sustainable mariculture strategies in Brazil.
Resumo:
The study of fossils has made considerable progress over the last years as a result of the use of new experimental techniques. This paper describes the chemical composition of a fossilized fish of the Cretaceous period, from a 100 million-year-old, material originated from the Araripe Basin (northeastern Brazil). The chemical composition of the fossilized fish was analyzed by means of X-ray powder diffraction and Fourier transform infrared spectroscopy (FT-IR). The spectroscopic study has proven that the main substances found in the fossilized fish are CaCO3 and Ca5(PO4)3(OH). A tentative mechanism to explain the fossilization process is also given.
Resumo:
Increasing natural gas use in Brazil triggered a discussion of its role as a Hg source. We show that Hg emissions to the atmosphere from fossil fuel combustion for power generation in Brazil contribute with 6.2% (4.2 t yr-1) to the total anthropogenic Hg atmospheric emissions, with coal combustion and biomass burning as major sources. Natural gas contributes with 0.04 t yr-1, mostly from electricity generation (88%) and industrial uses (7.6%). Preliminary results on Hg concentrations in natural gas suggest that a large fraction of it is trapped during refining and transport, which may create Hg point sources between extraction and consumption.
Resumo:
The main objective of this paper was to evaluate the level of occurrence of the organochlorine compounds in samples of sediments, bivalves and two fish species collected in the Piracicaba River basin (São Paulo, Brazil). The isomers alpha and gamma of HCH and Heptachlor were most frequently detected in samples of sediments and specimens of bivalve and fish. Therefore, although the levels of these compounds found were not critically high, they are still found in the environment. This fact suggests that they are still being used, despite the fact that the use of these compounds was outlawed more than twenty years ago.
Resumo:
Photosynthetic microorganism cultures, such as microalgae, represent one of the alternatives for fossil CO2 emissions mitigation. Carbon supply is the major cost component in microalgal cultures. Aiming to enhance the dissolved inorganic carbon uptake efficiency in microalgal cultures, Spirulina sp LEB-18 was cultivated in mediums containing NaHCO3 concentrations ranging from 2.8 to 100 g L-1. Results indicated that lower dissolved inorganic carbon concentratios (2.8 g L-1 NaHCO3) produce higher growth parameters (Xmax = 0.75 g L-1; Pmax = 0.145 g L-1 d-1; µmax = 0.254 d-1) and lower carbon losses (13.61%). At 50 g L-1 of NaHCO3 cell growth was inhibited and carbon losses reached 38.73%.
Resumo:
The cycle of fossil fuels as an energy source for mankind is approaching its end. Finite resources, coupled with greenhouse gas, have led to an increased effort in the search for alternative renewable energy sources. Brazil has a leading position, due to a 46% participation of renewable sources in its primary energy supply, compared to the global average of 12%. The expansion of the renewable sources in Brazil depends on medium and long term planning, and a large volume of investments. The present financial crisis will have major effects in the energy market. Despite a negative initial impact, it is expected that the rearrangement of the financial system will ultimately lead to an expansion in the use of renewable energy sources. Brazil is a tropical country, with the largest biodiversity in our planet and excellent conditions to expand the use of all forms of renewable sources.
Resumo:
The terpenoid composition of seven amber samples from Araripe Basin (Santana Formation, Crato Member) has been analyzed by gas chromatography-mass spectrometry to determine their botanical origin. The diterpenoids, which have been identified in the fossil resin extracts are derived primarily from the abietane class, e.g., dehydroabietane, 4-epidehydroabietol, 16,17,18-trisnorabieta-8,11,13-triene, 7-oxo-16,17,19-trisnorabieta-8,11,13-trieno, dehydroabietic acid, ferruginol, hinokiol and hinokione. Their composition is certainly typical for conifers, and angiosperms can be excluded as the botanical source, as no triterpene was identified. The terpenoid characteristics strongly support a relationship to the Araucariaceae or Podocarpaceae families. In addition, the fossil record of the embedding sediments (pollen and fossil leaves) also supports the proposal of these paleobotanical origins for the ambers.