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Search Results: 1 - 10 of 769710 matches for " A. F. D. C.;Morales-Carrera "
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Viabilidade do uso de argilas cauliníticas do Quadrilátero Ferrífero para a indústria ceramica
Peralta-Sánchez, M. G.;Morales-Carrera, A. M.;Varaj?o, A. F. D. C.;Ferreira, M. M.;
Ceramica , 2011, DOI: 10.1590/S0366-69132011000300002
Abstract: seven samples from three kaolin deposits of the quadrilátero ferrífero were characterized by physical, mineralogical and chemical analyses in order to determine their use in the ceramic industry. despite the predominant presence of kaolinite, the variations in the fe2o3 content from 2 to 44%, due to presence of goethite and hematite, resulted in different colors, namely: white (acm and db), yellow (r5), yellowed red (fs) and red (dv, r1 and am). specimens were burned at 900 and 1100 °c and they almost didn't change color. however, only specimens made with dv and r1 samples reached the technical specifications for the ceramic industry, without fractures and with values of compression strength of 96.2 and 64.2 mpa, respectively. the other samples were made by mixing phyllite in the proportions of 5, 10, 15, 20 and 25% and burned at 900 and 1100 °c. the bricks made with acm+15f, db+5f, r5+5f, fs+5f, am+5f and burned at 900 oc reached the technical specifications for ceramic industry, without fractures and with values of compression strength between 69.15 and 29.6 mpa.
Argilas bentoníticas da península de Santa Elena, Equador: pilariza??o, ativa??o ácida e seu uso como descolorante de óleo de soja
Morales-Carrera, Ana M.;Varaj?o, Angélica F. D. C.;Gon?alves, Marcos A.;Stachissini, Ant?nia S.;
Química Nova , 2009, DOI: 10.1590/S0100-40422009000900009
Abstract: two samples of calcic bentonite of the santa elena peninsula, ecuador, were pillared with al13 ions in the ratio of 10, 15 and 20 meq of al g-1 of clay, calcinated at 573, 723 and 873 ok and acid activated with 4, 6 and 8 mol l-1 h2so4. analyses by x-ray diffraction, x-ray fluorescence, differential and gravimetric thermal, density, surface area and porosity, were applied in order to study the modifications occurred in the crystalline structure of the montmorillonite. the 8 mol l-1 h2so4 acid-activated 15 meq of al g-1 of clay at 573 ok al-pillared samples indicated the best results in the bleaching of the soybean oil measured by uv-visible spectrophotometer.
Transforma??es mineralógicas e cristaloquímicas decorrentes dos ensaios termais em argilas cauliníticas ferruginosas
Ferreira, M. M.;Varaj?o, A. F. D. C.;Morales-Carrera, A. M.;Peralta-Sánchez, M. G.;Costa, G. M. da;
Ceramica , 2012, DOI: 10.1590/S0366-69132012000100017
Abstract: mineralogical and crystallochemical transformations of representative ferruginous kaolinitic clay samples were investigated in specimens burned at 800, 1000 and 1200 °c. x-ray diffraction and differential thermal and thermogravimetric analyses showed that kaolinite was the predominant mineral in the raw samples. the m?ssbauer spectroscopy results showed that the high iron content (22.5 wt.%), as determined by x-ray fluorescence, is related to the presence of goethite (18 wt.%) and hematite (16 wt.%). however, after fe was extracted using a dithionite-citrate system buffered with sodium bicarbonate, a residue of this element (fe3+ and fe2+) was found in the structure of the kaolinite. the sintering process showed the destruction of kaolinite, as well as the transformation of the goethite into hematite, the crystals growing as the temperature increases. the hematite crystal size at 1200 °c is five times larger than in the raw sample. the mullite formation at 1000 °c is comprised of a solid solution of fe2o3 and al2o3, which results in a resistant product with a higher thermal stability.
Mortalidad hospitalaria en un Servicio de Medicina Interna
Sanclemente,C.; Barcons,M.; Moleiro,Ma. A.; Alonso,F.; Pa?ella,D.; Carrera,R.; Toribio,R.; Anglada,A.; Vilaró,J.;
Anales de Medicina Interna , 2004, DOI: 10.4321/S0212-71992004000700002
Abstract: the internal medicine service of the hospital general de vic (barcelona) takes part in the mortality committee by revising and discussing in-hospital mortality. background: to establish the characteristics of the deceased, death causes and to revise possible changes in the last six-years time or problems related to the exitus, to evaluate and improve hospitalized patients' assistance. methodology: every case was revised following a specific register: demographical data, diagnosis and death cause, hospital death, documentation data, terminal or agonic situation when hospitalized, autopsies and death quality data. exitus due to hospital problems were analyzed and classified in different groups. the statistical analysis was performed with measures of central tendency and of standard deviation. results: during the revised six years, there were 819 exitus (5.1%). global average death age was 79 ± 1.8 years: 52.5% were men and 47.4% were women; 22.8% died in less than forty-eight hours after hospitalization. the most frequent death causes were cerebrovascular accident (24%), chronic obstructive pulmonary disease (14.4%) and pneumonia (9.6%). there were a small number of autopsies (4.8%). ratio of exitus due to hospital problems was stable during the six years (0.5%), in which nosocomial infection was the severest problem. conclusions: the total percentage of exitus was 5.1%, higher than the common standards. mortality causes coincide with other series. ratio of exitus due to hospital problems was according to recommended objectives. the number of autopsies was very small. a correct completing and revision of the clinical recording is indispensable to spot a shortage in the hospitalized patients' assistance.
ROSAC: Studying the clustering properties of X-ray selected AGNs
F. Tesch,F. J. Carrera,D. Engels,J. Hu,C. Ledoux,A. Ugryumov,D. Valls-Gabaud,W. Voges,J. Wei
Physics , 2000,
Abstract: We present the first ROSAC results of an AGN clustering analysis. This study comprises a sample of 200 AGNs, 75% of which being at low redshifts z<0.5, in the Ursa Major constellation. The spatial 2-point-correlation function (SCF) as well as the minimal spanning tree (MST) technique were applied. Some evidence for clustering is found in the SCF, although with low significance. Using the MST technique, we could find two AGN groups. This result is preliminary and the exact significance will be tested with careful simulations.
Clustering of X-ray selected Active Galactic Nuclei
F. J. Carrera,X. Barcons,A. C. Fabian,G. Hasinger,K. O. Mason,R. G. McMahon,J. P. D. Mittaz,M. J. Page
Physics , 1998, DOI: 10.1046/j.1365-8711.1998.01767.x
Abstract: A total of 235 Active Galactic Nuclei (AGN) from two different soft X-ray surveys (the ROSAT Deep Survey -DRS- and the ROSAT International X-ray Optical Survey -RIXOS-) with redshifts between 0 and 3.5 are used to study the clustering of X-ray selected AGN and its evolution. A 2 sigma significant detection of clustering of such objects is found on scales <40-80/h Mpc in the RIXOS sample, while no clustering is detected on any scales in the DRS sample. Assuming a single power law model for the spatial correlation function (SCF), quantitative limits on the AGN clustering have been obtained: a comoving correlation length 1.5<~ r_0 <~ 3.3/h Mpc is implied for comoving evolution, while 1.9 <~ r_0 <~ 4.8 for stable clustering and 2.2 <~ r_0 <~ 5.5 for linear evolution. These values are consistent with the correlation lengths and evolutions obtained for galaxy samples, but imply smaller amplitude or faster evolution than recent UV and optically selected AGN samples. We also constrain the ratio of bias parameters between X-ray selected AGN and IRAS galaxies to be <~1.7 on scales <~ 10/h Mpc, a significantly smaller value than is inferred from local large-scale dynamical studies.
Farmacovigilancia en Chile y el mundo PHARMASURVEILLANCE IN CHILE AND WORLDWILDE
Revista chilena de infectología , 2002,
Numerical chromosome polymorphism in Mikania cordifolia Willd. (Asteraceae)
Maffei, E.M.D.;Marin-Morales, M.A.;Ruas, P.M.;Ruas, C.F.;
Genetics and Molecular Biology , 1999, DOI: 10.1590/S1415-47571999000400023
Abstract: cytogenetical analysis of mikania cordifolia, from southeastern brazil, using the conventional feulgen method, showed a chromosome number of 2n = 36. previous karyotypic descriptions for this species showed a numerical chromosome variation of 2n = 34 to 38. there was a secondary constriction in every metaphase in the first chromosome pair, which constitutes a cytological marker. small extranumerary chromosomes with numerical variation in the same plant were found in the tenth chromosome pair.
Numerical chromosome polymorphism in Mikania cordifolia Willd. (Asteraceae)
Maffei E.M.D.,Marin-Morales M.A.,Ruas P.M.,Ruas C.F.
Genetics and Molecular Biology , 1999,
Abstract: Cytogenetical analysis of Mikania cordifolia, from southeastern Brazil, using the conventional Feulgen method, showed a chromosome number of 2n = 36. Previous karyotypic descriptions for this species showed a numerical chromosome variation of 2n = 34 to 38. There was a secondary constriction in every metaphase in the first chromosome pair, which constitutes a cytological marker. Small extranumerary chromosomes with numerical variation in the same plant were found in the tenth chromosome pair.
Chromosomal polymorphism in 12 populations of Mikania micrantha (Compositae)
Maffei Eliane M.D.,Marin-Morales M.A.,Ruas P.M.,Ruas C.F.
Genetics and Molecular Biology , 1999,
Abstract: Mikania micrantha is a climbing perennial weed of the family Asteraceae, with a vast distribution from South America to south of the United States. This species is widely distributed throughout Brazil, where it shows little morphological variation. Mitotic chromosomes of 12 populations of M. micrantha derived from several Brazilian sites were studied using Feulgen staining and C-banding. The populations included eight diploid (2n = 36 and 42) and four tetraploid (2n = 72) cytotypes. Chromosome numbers of 2n = 36 and 2n = 42 are reported for the first time for M. micrantha. These populations had a secondary constriction in the middle of the larger arm of chromosome pair 1, following the same pattern described for all Mikania species analyzed so far. Numerical and structural variation of the chromosomes was quite common among the karyotypes and nearly all cytotypes differed from each other in some aspect. Most of the chromosomal differentiation may be attributed to inversions and addition or deletion of DNA fragments. C-banding, applied to three of the 12 populations, also revealed polymorphism in the distribution of heterochromatin. Additionally, one to 14 supernumerary or B-chromosomes were observed. The Bs were detected in six of the 12 populations and varied in size, number, and structure among karyotypes and also among cells of the same root meristem. The B chromosomes were also heterochromatic, showing a C-banding pattern similar to the A chromosomes, and suggesting that they may be derived from the chromosomes of the A complement.
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