Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 1989
Pressureless sintering of Si3N 4 powder with 20 wt. % of mixed Y20~, Al203 and Si02 additives was... more Pressureless sintering of Si3N 4 powder with 20 wt. % of mixed Y20~, Al203 and Si02 additives was carried out at 1650 °C under 1 atm flowing N 2 for 15-480 min. The a ~ fl phase transformation and densification kinetics during the first sintering stages seem to be controlled by the additive composition. Glassy grain boundary crystallization of as-sintered materials was performed at 1000 to 1300 °C producing yttrium aluminium garnet, ~03 "2Si02, Si2N:O and an unknown phase.
A particular meshless method, named meshless local Petrov -Galerkin is investigated. To treat the... more A particular meshless method, named meshless local Petrov -Galerkin is investigated. To treat the essential boundary condition problem, an alternative approach is proposed. The basic idea is to merge the best features of two different methods of shape function generation: the moving least squares (MLS) and the radial basis functions with polynomial terms (RBFp). Whereas the MLS has lower computational cost, the RBFp imposes in a direct manner the essential boundary conditions. Thus, dividing the domain into different regions a hybrid method has been developed. Results show that it leads to a good trade-off between computational time and precision.
The Brachyspira (formerly Serpulina) species rrl gene encoding 23S ribosomal RNA (rRNA) was used ... more The Brachyspira (formerly Serpulina) species rrl gene encoding 23S ribosomal RNA (rRNA) was used as a target for ampli®cation of a 517 bp DNA fragment by polymerase chain reaction (PCR). The primers for PCR ampli®cation had sequences that were conserved among Brachyspira 23S rRNA gene and were designed from nucleotide sequences of Brachyspira hyodysenteriae, Serpulina intermedia, Brachyspira innocens and Brachyspira pilosicoli available from the GenBank database. Digestion of PCR-generated products from reference and ®eld isolates of swine intestinal spirochetes with restriction enzymes Taq I and Alu I revealed ®ve restriction fragment length polymorphism (RFLP) patterns. Each RFLP pattern corresponded to previously established genetic groups including B. hyodysenteriae (I), S. intermedia/B. innocens (II), Brachyspira murdochii (III), B. pilosicoli (IV) and B. alvinipulli (V). The 23S rRNA PCR/RFLP provided a relatively simple genotypic method for identi®cation of porcine pathogenic B. hyodysenteriae and B. pilosicoli. #
World Journal of Microbiology & Biotechnology, 1997
PCR assays were formatted using primer pairs homologous to phoE and invA genes. The amplification... more PCR assays were formatted using primer pairs homologous to phoE and invA genes. The amplification conditions were optimized with pure cultures and reactions were carried out to define selectivity, specificity and sensitivity of both primer pairs. The performance of the invA primer pair was better than that of the phoE pair, making the specific detection of Salmonella serovars and strains isolated from different food samples possible. Using the invA primer pair, the combined selective enrichment method with the polymerase chain reaction assay was established and used to detect Salmonella from artificially multi-contaminated food samples. The complete procedure detected as few as three cells of Salmonella (3 c.f.u.) from milk and meat samples.
World Journal of Microbiology & Biotechnology, 1994
Genomic DNA of 13 Bradyrhizobium japonicum strains was prepared and analysed by restriction fragm... more Genomic DNA of 13 Bradyrhizobium japonicum strains was prepared and analysed by restriction fragment length polymorphism (RFLP) with nif and nod probes, and by random amplified polymorphic DNA (RAPD) with 11 primers of arbitrary nucleotide sequence. Polymorphism was observed in both analyses. The RFLP and RAPD banding patterns of different strains were used to calculate genetic divergence and to construct phylogenetic trees, allowing studies on the relationships between the strains. RFLP with nif and nod probes permitted the separation of the strains into two divergent groups, whereas RAPD separated them into four main groups. RAPD allowed closely related strains to be distinguished.
We describe a nested polymerase chain reaction (PCR) for the detection of Babesia equi in equine ... more We describe a nested polymerase chain reaction (PCR) for the detection of Babesia equi in equine infected erythrocytes using oligonucleotides designed on the published sequence of a B. equi merozoite antigen gene (ema-1). A 102bp DNA fragment is specifically amplified from B. equi but not from Babesia caballi, Babesia bovis or Babesia bigemina DNA. In a mock infection we were able to detect down to six infected cells in 10(8) equine erythrocytes or to detect the parasite in blood with an equivalent parasitemia of 0.000006%. Furthermore, gene polymorphism was found by performing a PCR-RFLP (PCR combined with restriction fragment length polymorphism) on both the 102bp and the entire ema-1 gene DNA amplified from two B. equi isolates, Florida (USA) and Pelotas (Southern Brazil) isolates. The polymorphism was confirmed by sequencing the entire ema-1 gene from the B. equi isolate Pelotas. Our results demonstrate that the ema-1 based nested PCR is a valuable technique for routine detection of B. equi in chronically infected horses. It may be used for epidemiological and phylogenetic studies of the parasite as well as monitoring B. equi infected horses in chemotherapeutic trials.
Effects of Cinnamomum zeylanicum (cinnamon) on the labelling of blood constituents with technetiu... more Effects of Cinnamomum zeylanicum (cinnamon) on the labelling of blood constituents with technetium-99 m( 99m Tc) and on the morphology of red blood cells were studied. Blood samples from Wistar rats were incubated with cinnamon extract for 1hour or with 0.9% NaCl, as control. Labelling of blood constituents with 99m Tc was performed. Plasma (P) and blood cells (BC), soluble (SF-P and SF-BC) and insoluble (IF-P and IF-BC) fractions were separated. The radioactivity in each fraction was counted and the percentage of radioactivity incorporated (%ATI) was calculated. Blood smears were prepared, fixed, stained and the qualitative and quantitative morphological analysis of the red blood cells was evaluated. The data showed that the cinnamon extract decreased significantly (po0.05) the %ATI on BC, IF-P and IF-BC. No modifications were verified on shape of red blood cells. Cinnamon extracts could alter the labelling of blood constituents with 99m Tc, and although our results were obtained with animals, precaution is suggested in interpretations of nuclear medicine examinations involving the labelling of blood constituents in patients who are using cinnamon. r
We studied the influence of a commercial extract of Paullinia cupana (guarana) on the binding of ... more We studied the influence of a commercial extract of Paullinia cupana (guarana) on the binding of technetium-99m-dimercaptosuccinic acid ( 99m Tc-DMSA) on blood constituents. Plasma (P) and blood cells (BC) from Wistar rats (control and treated) were separated. P and BC were precipitated with trichloroacetic acid (TCA) or ammonium sulphate (AS) and soluble (SF) and insoluble fractions (IF) isolated. The percentage of incorporated radioactivity (%ATI) in each fraction was determined. The treatment influenced the %ATI in IF-P and in IF-BC isolated by TCA precipitation. r
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 1989
Pressureless sintering of Si3N 4 powder with 20 wt. % of mixed Y20~, Al203 and Si02 additives was... more Pressureless sintering of Si3N 4 powder with 20 wt. % of mixed Y20~, Al203 and Si02 additives was carried out at 1650 °C under 1 atm flowing N 2 for 15-480 min. The a ~ fl phase transformation and densification kinetics during the first sintering stages seem to be controlled by the additive composition. Glassy grain boundary crystallization of as-sintered materials was performed at 1000 to 1300 °C producing yttrium aluminium garnet, ~03 "2Si02, Si2N:O and an unknown phase.
A particular meshless method, named meshless local Petrov -Galerkin is investigated. To treat the... more A particular meshless method, named meshless local Petrov -Galerkin is investigated. To treat the essential boundary condition problem, an alternative approach is proposed. The basic idea is to merge the best features of two different methods of shape function generation: the moving least squares (MLS) and the radial basis functions with polynomial terms (RBFp). Whereas the MLS has lower computational cost, the RBFp imposes in a direct manner the essential boundary conditions. Thus, dividing the domain into different regions a hybrid method has been developed. Results show that it leads to a good trade-off between computational time and precision.
The Brachyspira (formerly Serpulina) species rrl gene encoding 23S ribosomal RNA (rRNA) was used ... more The Brachyspira (formerly Serpulina) species rrl gene encoding 23S ribosomal RNA (rRNA) was used as a target for ampli®cation of a 517 bp DNA fragment by polymerase chain reaction (PCR). The primers for PCR ampli®cation had sequences that were conserved among Brachyspira 23S rRNA gene and were designed from nucleotide sequences of Brachyspira hyodysenteriae, Serpulina intermedia, Brachyspira innocens and Brachyspira pilosicoli available from the GenBank database. Digestion of PCR-generated products from reference and ®eld isolates of swine intestinal spirochetes with restriction enzymes Taq I and Alu I revealed ®ve restriction fragment length polymorphism (RFLP) patterns. Each RFLP pattern corresponded to previously established genetic groups including B. hyodysenteriae (I), S. intermedia/B. innocens (II), Brachyspira murdochii (III), B. pilosicoli (IV) and B. alvinipulli (V). The 23S rRNA PCR/RFLP provided a relatively simple genotypic method for identi®cation of porcine pathogenic B. hyodysenteriae and B. pilosicoli. #
World Journal of Microbiology & Biotechnology, 1997
PCR assays were formatted using primer pairs homologous to phoE and invA genes. The amplification... more PCR assays were formatted using primer pairs homologous to phoE and invA genes. The amplification conditions were optimized with pure cultures and reactions were carried out to define selectivity, specificity and sensitivity of both primer pairs. The performance of the invA primer pair was better than that of the phoE pair, making the specific detection of Salmonella serovars and strains isolated from different food samples possible. Using the invA primer pair, the combined selective enrichment method with the polymerase chain reaction assay was established and used to detect Salmonella from artificially multi-contaminated food samples. The complete procedure detected as few as three cells of Salmonella (3 c.f.u.) from milk and meat samples.
World Journal of Microbiology & Biotechnology, 1994
Genomic DNA of 13 Bradyrhizobium japonicum strains was prepared and analysed by restriction fragm... more Genomic DNA of 13 Bradyrhizobium japonicum strains was prepared and analysed by restriction fragment length polymorphism (RFLP) with nif and nod probes, and by random amplified polymorphic DNA (RAPD) with 11 primers of arbitrary nucleotide sequence. Polymorphism was observed in both analyses. The RFLP and RAPD banding patterns of different strains were used to calculate genetic divergence and to construct phylogenetic trees, allowing studies on the relationships between the strains. RFLP with nif and nod probes permitted the separation of the strains into two divergent groups, whereas RAPD separated them into four main groups. RAPD allowed closely related strains to be distinguished.
We describe a nested polymerase chain reaction (PCR) for the detection of Babesia equi in equine ... more We describe a nested polymerase chain reaction (PCR) for the detection of Babesia equi in equine infected erythrocytes using oligonucleotides designed on the published sequence of a B. equi merozoite antigen gene (ema-1). A 102bp DNA fragment is specifically amplified from B. equi but not from Babesia caballi, Babesia bovis or Babesia bigemina DNA. In a mock infection we were able to detect down to six infected cells in 10(8) equine erythrocytes or to detect the parasite in blood with an equivalent parasitemia of 0.000006%. Furthermore, gene polymorphism was found by performing a PCR-RFLP (PCR combined with restriction fragment length polymorphism) on both the 102bp and the entire ema-1 gene DNA amplified from two B. equi isolates, Florida (USA) and Pelotas (Southern Brazil) isolates. The polymorphism was confirmed by sequencing the entire ema-1 gene from the B. equi isolate Pelotas. Our results demonstrate that the ema-1 based nested PCR is a valuable technique for routine detection of B. equi in chronically infected horses. It may be used for epidemiological and phylogenetic studies of the parasite as well as monitoring B. equi infected horses in chemotherapeutic trials.
Effects of Cinnamomum zeylanicum (cinnamon) on the labelling of blood constituents with technetiu... more Effects of Cinnamomum zeylanicum (cinnamon) on the labelling of blood constituents with technetium-99 m( 99m Tc) and on the morphology of red blood cells were studied. Blood samples from Wistar rats were incubated with cinnamon extract for 1hour or with 0.9% NaCl, as control. Labelling of blood constituents with 99m Tc was performed. Plasma (P) and blood cells (BC), soluble (SF-P and SF-BC) and insoluble (IF-P and IF-BC) fractions were separated. The radioactivity in each fraction was counted and the percentage of radioactivity incorporated (%ATI) was calculated. Blood smears were prepared, fixed, stained and the qualitative and quantitative morphological analysis of the red blood cells was evaluated. The data showed that the cinnamon extract decreased significantly (po0.05) the %ATI on BC, IF-P and IF-BC. No modifications were verified on shape of red blood cells. Cinnamon extracts could alter the labelling of blood constituents with 99m Tc, and although our results were obtained with animals, precaution is suggested in interpretations of nuclear medicine examinations involving the labelling of blood constituents in patients who are using cinnamon. r
We studied the influence of a commercial extract of Paullinia cupana (guarana) on the binding of ... more We studied the influence of a commercial extract of Paullinia cupana (guarana) on the binding of technetium-99m-dimercaptosuccinic acid ( 99m Tc-DMSA) on blood constituents. Plasma (P) and blood cells (BC) from Wistar rats (control and treated) were separated. P and BC were precipitated with trichloroacetic acid (TCA) or ammonium sulphate (AS) and soluble (SF) and insoluble fractions (IF) isolated. The percentage of incorporated radioactivity (%ATI) in each fraction was determined. The treatment influenced the %ATI in IF-P and in IF-BC isolated by TCA precipitation. r
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