High-pressure assisted sintering of Ti-20Si-10B and Ti-10Si-5B powders

This work presents the structural characterization of Ti-10Si-5B and Ti-20Si-10B (at-%) alloys produced by high-pressure assisted sintering. Sintering was performed in air at 1100 and 1200°C for 60 s using pressure levels of 5 GPa. Structural evaluation of sintered samples was conducted by means of scanning electron microscopy and energy dispersive spectrometry. Samples were successfully consolidated after sintering, which presented theoretical density values higher than 99%. The microstructures of the sintered Ti-10Si-5B and Ti-20Si-10B alloys revealed the presence of the TiSS, TiB, TiB2, Ti5Si3, Ti5Si4, TiSi, and TiSi2.phases. A small amount of Ti6Si2B was formed after high-pressure assisted sintering of the Ti-20Si-10B alloy (5GPa, 1100°C for 60 s) indicating that equilibrium structures were not achieved during short sintering times. No oxygen and carbon contamination was detected in structures of Ti-Si-B alloys after high-pressure sintering at 1100 and 1200°C without controlled atmosphere. © (2012) Trans Tech Publications, Switzerland.

La industria de bienes de capital en América Latina y el Caribe: su desarrollo en un marco de cooperación regional

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Life mode of in situ Conularia in a Middle Devonian epibole

Exceptionally abundant specimens of Conularia aff. desiderata Hall occur in multiple marine obrution deposits, in a single sixth-order parasequence composed of argillaceous and silty very fine sandstone, in the Otsego Member of the Mount Marion Formation (Middle Devonian, Givetian) in eastern New York State, USA. Associated fossils consist mostly of rhynchonelliform brachiopods but also include bivalve molluscs, orthoconic nautiloids, linguliform brachiopods and gastropods. Many of the brachiopods, bivalve molluscs and conulariids have been buried in situ. Conulariids buried in situ are oriented with their aperture facing obliquely upward and with their long axis inclined at up to 87degree to bedding. Most specimens are solitary, but some occur in V-like pairs or in radial clusters consisting of three specimens, with the component specimens being about equally long or (less frequently) substantially different in length. The compacted apical end of Conularia buried in situ generally rests upon argillaceous sandstone. With one possible exception, none of the examined specimens terminates in a schott (apical wall), and internal schotts appear to be absent. The apical ends of specimens in V-like pairs and radial clusters show no direct evidence of interconnection of their periderms. The apical, middle or apertural region of some inclined specimens abuts or is in close lateral proximity to a recumbent conulariid or to one or more spiriferid brachiopods, some of which have been buried in their original life orientation. The azimuthal bearings of Conularia and nautiloid long axes and the directions in which conulariids open are nonrandom, with conulariids being preferentially aligned between 350 and 50degree and with their apertural end facing north-east, and nautiloids being preferentially aligned between 30 and 70degree. Otsego Member Conularia were erect or semi-erect, epifaunal or partially infaunal animals, the apical end of which rested upon very fine bottom sediment. The origin of V-like pairs and radial clusters remains enigmatic, but it is probable that production of schotts was not a regular feature of this animal's life history. Finally, conulariids and associated fauna were occasionally smothered by distal storm deposits, under the influence of relatively weak bottom currents. © The Palaeontological Association.

Tafonomia dos Pygocephalomorpha (Crustacea, Peracarida, Malacostraca), Permiano, Bacia do Paraná, Brasil, e seu significado paleoambiental

Taphonomy of the pygocephalomorpha (Crustacea, Peracarida, Malacostraca), Permian, Paraná Basin, Brazil, and its paleoenvironmental meaning. Crustaceans (Pygocephalomorpha, Peracarida) are the main fossil invertebrates recorded in the Early Permian Assistência Formation, Irati Subgroup, State of São Paulo, Paraná Basin. For this study, samples taken from the base of the Ipeúna Member, Bairrinho Bed, State of São Paulo, were analyzed and complemented by fossils from the Irati Formation, State of Rio Grande do Sul. The taphonomic spectrum of the pygocephalomorphs includes three main preservational modes: Type 1. Complete pygocephalomorphs (with outstretched or flexed abdomen), which are associated to cream-colored mudstones and more commonly to black shales. In rare cases, molds of soft parts are preserved. They suffered rapid burial (hours to days) by mud blankets associated to storm events in anoxic bottoms, below storm wave base with minimum bottom disruption, followed by low rates of background sedimentation; Type 2. Partly articulated (carapace and abdomen, with or without caudal fan and without appendages) pygocephalomorphs, with extended or flexed abdomen, which are present in cream-colored pelites, associated with hummocky cross-stratifications, intercalated with black shales. These may represent individuals or remains lying in the sediment-water interface preserved by rapid burial associated to episodic sedimentation events; Type 3. Disarticulated pygocephalomorphs, with isolated carapaces, abdomen, or abdominal segments. This is the predominant preservational mode in our samples. The skeletal remains can be found isolated or in dense, bioclast-supported concentrations (micro-coquines), representing proximal to distal tempestites. Finally, the extreme preservational quality seen in crustaceans of the Type 1 recorded in black shales, occasionally with molds of soft parts, indicates that the host rocks may represent Konservat-Lagerstätten deposits, as already suggested to coeval occurrences of the Irati Formation in Uruguay. © 2013 by the Sociedade Brasileira de Paleontologia.

Alternative interpretations of some earliest ediacaran fossils from China

In a letter to Nature (February, 2011), Xunlai Yuan and collaborators recorded carbon compression fossils from black shales of the Lantian Formation (Ediacaran), southern Anhui Province, South China. The new fossils, described under five morphological types (Types A to E), exhibit degrees of morphological differentiation suggesting that they were multicellular eukaryotes. Some of the Lantian macrofossils were interpreted as algae, but others are of unknown affinities. For reasons noted in this discussion, Type A fossils attracted our particular attention, and we suggest an alternative interpretation of their affinities. According to our view, some of them (at least those with three faces and no globose holdfast at their base) may represent conulariid cnidarians or close medusozoan relatives. The undistorted organism probably was a three-sided cone in life. We believe that our suggested alternative interpretations of the anatomy and affinities of the fossils in question can be useful in guiding future research on the oldest currently known fossil assemblage of multicellular organisms. Copyright © 2012.

Acute aerocystitis in Piaractus mesopotamicus: Participation of eicosanoids and pro-inflammatory cytokines

A total of 360 pacus (Piaractus mesopotamicus) were used to study vascular permeability (VP) and inflammatory cell component (CC) in induced aerocystitis in P. mesopotamicus through inoculation of inactivated Aeromonas hydrophila, and the effect of steroidal and nonsteroidal anti-inflammatory drugs. It was observed that after inoculation of A. hydrophila, the maximum VP occurred 180 min post-stimulus (MPS). Pretreatment with anti-inflammatory drugs inhibited VP, and the inhibitory effect of dexamethasone was seen earlier than the effects caused by meloxicam and indomethacin. Inoculation of the bacterium caused a gradual increase in the accumulation of cells, which reached a maximum 24 h post-stimulus (HPS). Pretreatment with dexamethasone, indomethacin and meloxicam reduced the accumulation of lymphocytes, thrombocytes, granulocytes and macrophages. There was no significant difference between the different doses of the drugs tested. The results suggest that eicosanoids and pro-inflammatory cytokines participate in chemical mediation in acute inflammation in pacus. © 2013 Elsevier Ltd.

Temario provisional anotado

Documento de trabajo de la Primera reunión del Comité Ejecutivo de la CEA-CEPAL, Brasil, Rio de Janeiro, 25-26 marzo de 2002.

Disseminação de Rickettsia rickettsii nas glândulas salivares e ovários de fêmeas de Rhipicephalus sanguineus (Latreille 1806) (Acari:Ixodidae) por meio da aplicação de técnicas morfológicas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação dos efeitos do inseticida imidacloprido para abelhas sem ferrão Scaptotrigona postica Latreille, 1807 (Hymenoptera, Apidae, Meliponini): Hellen Maria Soares. -

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Transformación de la agricultura campesina y el rol del mercado de trabajo

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A imagem do Papa Bento XVI na imprensa brasileira: a cobertura da Folha de S. Paulo sobre a pedofilia

Pós-graduação em Comunicação - FAAC