In this work, the influence of hydrogen on the microstructure and fracture toughness of API 5L X80 high strength pipeline steel welded by friction stir welding was assessed. Samples were hydrogenated ...at room temperature for a duration of 10 h in a solution of 0.1 M H2SO4 + 10 mg L−1 As2O3, with an intensity current of 20 mA cm−2. Fracture toughness tests were performed at 0 °C in single-edged notched bending samples, using the Critical Crack Tip Opening Displacement (CTOD) parameter. Notches were positioned in different regions within the joint, such as the stir zone, hard zone, and base material. Hydrogen induces internal stress between bainite packets and ferrite plates within bainite packets. Besides, hydrogen acted as a reducer of the strain capacity of the three zones. The base metal had a moderate capacity to resist stable crack growth, displaying a ductile fracture mechanism. While the hard zone showed a brittle behavior with CTOD values below the acceptance limits for pipeline design (0.1–0.2 mm). The fracture toughness of the stir zone is higher than that of the base metal. Nevertheless, the stir zone displayed higher data dispersion due to its high inhomogeneity. Hence, it can also show a brittle behavior with critical CTOD values.
•Hydrogen embrittlement of an FSW welded joint of a pipeline steel is studied.•The role of hydrogen on the microstructure and fracture toughness.•Samples were hydrogenated at room temperature during 10 h in a solution.•The embrittlement affected much more the stir and hard zone, than the base metal.•H-charged samples with fine bainite and ferrite present high toughness.
This work evaluates the suitability and quality of Aphis gossypii, Brevicoryne brassicae, Myzus persicae, Rhopalosiphum maidis and Schizaphis graminum as hosts for Aphidius colemani. Twenty ...second-instar nymphs of each aphid species were exposed to parasitism for one hour, and then kept in a climatic chamber at 22+/-1 deg C, 70+/-10% RH and a 12 h photophase. The aphid B. brassicae was unsuitable for the development of A. colemani. The different aphid host species varied in size: M. persicae more than (R. maidis = S. graminum) more than A. gossypii. Parasitoid fitness decreased accordingly when reared on (M. persicae = R. maidis) more than S. graminum more than A. gossypii. Large hosts seem to be better than small hosts based on parasitoid size. Egg load of A. colemani was related probably more with the ability of the parasitoid larva to obtain nutritional resources from the different host species than with host size.
BCR::ABL1-negative myeloproliferative neoplasms are hematopoietic disorders characterized by panmyelosis. JAK2 V617F is a frequent variant in these diseases and often occurs in the 46/1 haplotype. ...The G allele of rs10974944 has been shown to be associated with this variant, specifically its acquisition, correlations with familial cases, and laboratory alterations. This study evaluated the association between the 46/1 haplotype and JAK2 V617F in patients with myeloproliferative neoplasms in a population from the Brazilian Amazon. Clinical, laboratory and molecular sequencing analyses were considered. Carriers of the G allele of rs10974944 with polycythemia vera showed an increase in mean corpuscular volume and mean corpuscular hemoglobin, while in those with essential thrombocythemia, there was an elevation in red blood cells, hematocrit, and hemoglobin. Associations were observed between rs10974944 and the JAK2 V617F, in which the G allele (OR 3.4; p < 0.0001) and GG genotype (OR 4.9; p = 0.0016) were associated with JAK2 V617F + and an increase in variant allele frequency (GG: OR 15.8; p = < 0.0001; G: OR 6.0; p = 0.0002). These results suggest an association between rs10974944 (G) and a status for JAK2 V617F, JAK2 V617F + _VAF ≥ 50%, and laboratory alterations in the erythroid lineage.
One of the main difficulties in studying dengue virus infection in
humans and in developing a vaccine is the absence of a suitable animal
model which develops the full spectrum of dengue fever, ...dengue
haemorrhagic fever, and dengue shock syndrome. It is our proposal to
present morphological aspects of an animal model which shows many
similarities with the dengue infection in humans. BALB/c mice were
intraperitoneally infected with non-neuroadapted dengue virus serotype
2 (DENV-2). Histopathological and morphometrical analyses of liver
tissue revealed focal alterations along the infection, reaching
wide-ranging portal and centrolobular veins congestion and sinusoidal
cell death. Additional ultrastructural observations demonstrated
multifocal endothelial injury, platelet recruitment, and alterated
hepatocytes. Dengue virus antigen was detected in hepatocytes and in
the capillar endothelium of the central lobular vein area. Liver
function tests showed high levels of aspartate transaminase and alanine
transaminase enzyme activity. Lung tissue showed interstitial pneumonia
and mononuclear cells, interseptal oedema, hyperplasia, and hypertrophy
of the bronchiolar epithelial cells. DENV-2 led to a transient
inflammatory process, but caused focal alterations of the
blood-exchange barrier. Viremia was observed from 2nd to 11th day p.i.
by isolation of DENV-2 in C6/36 mosquito cell line inoculated with the
supernatant of macerated liver, lung, kidney, and cerebellum tissues of
the infected mice.
Glial cells have been implicated in temporal lobe epilepsy in humans and in its models. Astrocytes are lost in several brain regions after acute seizures induced by pilocarpine and may suffer ...hyperplasia at subsequent time points. This study investigated the effect of N-methyl-(2S,4R)-trans-4-hydroxy-L-proline (NMP) on astrocytes exposed to cytotoxic concentrations of pilocarpine. Astrocytes were incubated with pilocarpine (half maximal inhibitory concentration (IC.sub.50)=31.86 mM) for 24 h. Afterwards, they were treated with NMP at concentrations ranging from 3.12 to 100 microg/mL for 24 h. Cell viability was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cytoplasmic reactive oxygen species (ROS) and mitochondrial transmembrane potential (DELTAPSIm) were analyzed by flow cytometry using 2',7'-dichlorofluorescein diacetate (DCFH-DA) and rhodamine-123 (Rho123), respectively. Expression of glial fibrillary acidic protein (GFAP) and voltage-dependent anion channel-1 (VDAC-1) were measured by western blot. Pilocarpine significantly decreased cell viability and mitochondrial potential and increased ROS concentration significantly by 6.7 times compared to the control. NMP concentrations greater than or equal to 25 mg/mL protected astrocytes against pilocarpine-induced injury in a concentration-dependent manner. Concomitantly, NMP reduced cytoplasmic ROS accumulation to 27.3, 24.8, and 12.3% in the groups treated with 25, 50, and 100 mg/mL NMP, respectively. NMP also protected mitochondria from pilocarpine- induced depolarization. These effects were associated with improvement of pilocarpine-induced GFAP and VDAC-1 overexpression, which are important biomarkers of astrocyte dysfunction. In conclusion, the improvement of ROS accumulation, VDAC- 1 overexpression, and mitochondrial depolarization are possible mechanisms of the NMP protective action on reactive astrocytes. Key words: Temporal lobe epilepsy; Voltage-dependent anion channel; Mitochondrial transmembrane potential; Oxidative stress
Aphid parasitoids (Hymenoptera, Braconidae, Aphidiinae) and their associations related to biological control in Brazil Starý, Petr(Czech Academy of Sciences Institute of Entomology); Sampaio, Marcus Vinicius(Universidade Federal de Lavras Departamento de Entomologia ,Universidade Federal de Uberlândia Instituto de Ciências Agrárias); Bueno, Vanda Helena Paes(Universidade Federal de Lavras Departamento de Entomologia)
Revista Brasileira de Entomologia,
03/2007, Letnik:
51, Številka:
1
Journal Article
Recenzirano
Odprti dostop
This study evaluated the parasitoid-aphid-plant associations in Brazil with the objective of developing a useful research database for further studies of aphid parasitoid ecology and aphid ...management. The original material was obtained from collections made in Paraná, Rio Grande do Sul, Minas Gerais, and São Paulo states. The published information on the Aphidiinae in Brazil is revised. The general features of the target parasitoid fauna of Central and South America is summarized and promising biological control programs of some aphid species in Brazil is discussed.
Este trabalho avaliou as interações parasitóides-pulgão-planta no Brasil, com o objetivo de desenvolver um banco útil de dados para estudos subseqüentes em ecologia de parasitóides de afídeos e manejo de pulgões. O material original foi obtido de coletas nos estados do Paraná, Rio Grande do Sul, Minas Gerais e São Paulo, sendo revisadas as informações sobre Aphidiinae publicadas no Brasil. Foram também sumarizadas as caracteristicas gerais da fauna de parasitóides das Américas Central e do Sul e discutidos os programas potenciais de controle biológico de algumas espécies de pulgões no Brasil.
We present a systematic structural, microstructural and magnetic characterization of the hexagonal δ-FeSe nanophase produced by a simple one-step mechanochemical synthesis route, by using ...conventional X-ray powder diffraction (XRPD), Rietveld refinement, transmission electron microscopy (TEM) and magnetometry techniques. We observed the simultaneous formation of tetragonal β-FeSe and δ-FeSe after 3 h of milling (with minor amounts of unreacted iron), followed by complete β-FeSe → δ-FeSe phase transition as milling time increases to 6 h (no unreacted iron). The average crystallite size of the δ-FeSe phase of about 16 nm after 3 h milling time decreases by about 31% up to the final milling time (24 h). TEM images and electron diffraction patterns confirm the nanometric size of the crystalline domains in the irregularly-shaped agglomerated particles. Two ferromagnetic phases with distinct coercivity spectra were assumed here by considering an assembly of randomly-oriented weakly-anisotropic ferromagnetic particles, mixed at a 4 to 6 volume ratio with other randomly-oriented ferromagnetic grains. Four years after synthesis, the aged samples milled for less than 9 h revealed a certain amount of the β-FeSe phase that slightly affects the δ-FeSe (micro)structure but causes some variations (decreasing) in magnetic parameters. Milling times as long as 12 h were shown to be necessary to guarantee the δ-FeSe nanophase stability and to retain its magnetic properties over time.
We present a systematic structural, microstructural and magnetic characterization of the hexagonal δ-FeSe nanophase produced by mechanochemical synthesis. The aged samples showed chemical instability and lower values of magnetic parameters.
This paper presents 23 years (1992–2014) of quasi-continuous measurements of the total ozone column (TOC) over the Southern Space Observatory (SSO) in São Martinho da Serra, Brazil (29.26° S, 53.48° ...and 488 m altitude). The TOC was measured by a Brewer spectrometer, and the results are also compared to daily and monthly observations from the TOMS (Total Ozone Mapping Spectrometer) and OMI (Ozone Monitoring Instrument) satellite instruments. Analyses of the main interannual modes of variability computed using the wavelet transform method were performed. A favorable agreement between the Brewer spectrophotometer and satellite datasets was found. The seasonal TOC variation is dominated by an annual cycle, with a minimum of approximately 260 DU in April and a maximum of approximately 295 DU in September. The wavelet analysis applied in the SSO TOC anomaly time series revealed that the Quasi-Biennial Oscillation (QBO) modulation was the main mode of interannual variability. The comparison between the SSO TOC anomaly time series with the QBO index revealed that the two are in opposite phases.
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