Rafael Duarte - Academia.edu (original) (raw)
Papers by Rafael Duarte
Journal of The World Aquaculture Society, 2010
Tambaqui, Colossoma macropomum, were fed with three vitamin C levels and two iron levels for 21 d... more Tambaqui, Colossoma macropomum, were fed with three vitamin C levels and two iron levels for 21 d: Diet 1 without vitamin C and with 30 mg of iron/kg; Diet 2 with 100 mg of vitamin C and 30 mg of iron/kg; and Diet 3 with 100 mg of vitamin C and 300 mg of iron/kg. Mortality was not observed during the feeding experiment. There were no changes in hematological parameters in fish that were fed the different diets. Iron contents in liver, muscle, and plasma were significantly different in fish fed with different iron content in the diets; when associated with vitamin C, changes were observed only for plasma iron. Therefore, tambaqui exhibits varied iron absorption in response to different levels of iron with and without vitamin C, a conclusion consistent with findings for other species of fish.
Progress in Organic Coatings, 2005
In this work, the protection conferred by Cr(VI)-containing and Cr-free pre-treatments and primer... more In this work, the protection conferred by Cr(VI)-containing and Cr-free pre-treatments and primers used in hot dip galvanized steel (HDG) coated systems were studied. The EIS results showed a differentiated behaviour for the specimens with Cr(VI) compared to the chromium-free ones. The samples with Cr(VI), both in the pre-treatment and in the primer, presented a better corrosion performance when compared to the Cr-free ones.Moreover, it can be said that the pre-treated and primed samples without Cr(VI) presented lower resistive properties and higher delamination fractions throughout the immersion time. The amount of Cr in the primer also influenced the coating resistance for shorter periods of immersion, but for long periods the passivating effect of Cr seems to be determinant.When topcoat was applied, i.e. for a complete system, the Cr-free specimens performed better than the Cr(VI)-containing ones, perhaps due to a better adhesion of the topcoat to the primer in the former case. This leads to the conclusion that there is a risk in assessing the behaviour of a paint scheme on the basis of the individual behaviour of each layer.
Progress in Organic Coatings, 2005
This work reports a comparative study on the corrosion resistance of AA2024-T3 pre-treated with t... more This work reports a comparative study on the corrosion resistance of AA2024-T3 pre-treated with three different silane solutions. The silanes used for the pre-treatments of the AA2024-T3 panels were: 1,2-bis(triethoxysilyl)ethane (BTSE), bis-[triethoxysilylpropyl]tetrasulfide (BTESPT) and γ-mercaptopropyltrimethoxysilane (γ-MPS). The analytical characterisation of the silane films was performed by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The corrosion performance of the pre-treated substrates was evaluated by electrochemical impedance spectroscopy (EIS). The results show that the pre-treatments based on silanes provide good corrosion protection of unpainted AA2024-T3. Painted substrates, previously pre-treated with the silane solutions also revealed improved corrosion resistance and good adhesion properties. Fatigue tests show that the silane pre-treatments do not affect the fatigue behaviour of the AA2024-T3. The work also discusses the formation of the protective silane films.
![Research paper thumbnail of Analytical characterisation and corrosion behaviour of bis-[triethoxysilylpropyl]tetrasulphide pre-treated AA2024-T3](https://attachments.academia-assets.com/50092149/thumbnails/1.jpg)
](Corrosion Science, 2005
This work aims at studying the corrosion behaviour of AA2024-T3 pre-treated with bis-[triethoxysi... more This work aims at studying the corrosion behaviour of AA2024-T3 pre-treated with bis-[triethoxysilylpropyl]tetrasulphide. Simultaneously, the work investigates the influence of the Cu-rich intermetallic particles on the formation of the silane film. The analytical characterisation of the silane films was performed by Auger electron spectroscopy and X-ray photoelectron spectroscopy. The corrosion performance of the pre-treated substrates was evaluated by electrochemical impedance spectroscopy. Atomic force microscopy associated with Kelvin probe was also used to determine the influence of the silane film on the Volta potential distribution on the alloy surface. The results show that copper present in the intermetallics plays an important role on the film formation.
Progress in Organic Coatings, 2009
In this work, a new and more intricate model of estimate water uptake inside an organic coating b... more In this work, a new and more intricate model of estimate water uptake inside an organic coating by impedance measurements is proposed, the tortuosity pore model (TPM). In this model, the organic coating (film) is considered to be a ternary system, composed of liquid (solution), solid (coating matrix) and gas (air) phases. Moreover, the pores tortuosity inside the coating is taken into consideration. Comparison between this new model and the other models found in the literature will be presented, showing that this new model presents for water uptake better correlation with the values obtained by gravimetry.
Electrochimica Acta, 2004
Cr(VI)-based pre-treatments have been in use for long time on several materials, however, they ar... more Cr(VI)-based pre-treatments have been in use for long time on several materials, however, they are target of great criticism and in the near future they could be definitely banned. The actual alternatives to Cr(VI) show pros and cons when sets of key properties are considered such as: corrosion resistance, adhesion of organic coatings, fatigue resistance, reliability and quality control. However, some of the possible alternatives show high potential, if some improvements are carried out and the if mechanisms involved are more deeply understood.
This study evaluated the biodiversity of 28 clinical and 24 environmental Mycobacterium isolates ... more This study evaluated the biodiversity of 28 clinical and 24 environmental Mycobacterium isolates from Rio de Janeiro, Brazil, by using hsp65 sequences, with the aim of contributing to a better understanding of the genetic diversity and usefulness of this marker. An extensive phylogenetic analysis was performed. The nucleotide diversity was similar between clinical (0.06508) and environmental (0.06221) isolates.
This work presents a technique to estimate the parameters of the restoration filter more suitable... more This work presents a technique to estimate the parameters of the restoration filter more suitable for correction on CBERS-2 CCD images through data mining techniques.
Information on the characteristics of Streptococcus agalactiae obtained from bovine sources in Br... more Information on the characteristics of Streptococcus agalactiae obtained from bovine sources in Brazil is still very limited. The aim of this study was to assess the phenotypic and genotypic diversity among S. agalactiae isolates from milk of dairy cows presenting clinical or subclinical mastitis in the southeast region of Brazil. Phenotypic characterization was based on physiological and serological tests. Antimicrobial susceptibility tests were carried out by the disk method. Genetic diversity was evaluated by using random amplified polymorphic DNA-PCR (RAPD-PCR) (by using the primer 1254) and pulsed-field gel electrophoresis (PFGE) (by using SmaI as the restriction enzyme) and by PCRs for detection of genes associated with resistance to erythromycin and tetracycline as well as PCRs for detection of genes coding for cell surface-associated proteins. According to the results of physiologic tests, 45 (52.9%) isolates showed beta-hemolysis and 44 (51.7%) were susceptible to bacitracin. Fourteen different biotypes were detected. The two most frequent biotypes comprised strains that were non-beta-hemolytic; fermented galactose, lactose, and salicin; produced protease; and were negative for DNase production. Serotype III was predominant (66 isolates [77.6%]), followed by serotypes II, Ia, Ib, and VI. Resistance to tetracycline and erythromycin was found in 38 (44.7%) and 9 (10.5%) isolates, respectively, with tet(O) (31.7%) and erm(B) (100%) being the most frequently occurring resistance genes. Three genes coding for surface proteins, bca, lmb, and scpB, were detected in 55 (64.7%), 7 (8.2%), and 43 (50.5%) isolates, respectively. In most cases, isolates from animals in the same herd presented closely related genetic profiles (determined by either RAPD-PCR or PFGE), which were distinct from those of isolates from different herds.
The phenotypic and genotypic characteristics of 25 Streptococcus porcinus isolates recovered from... more The phenotypic and genotypic characteristics of 25 Streptococcus porcinus isolates recovered from human sources were investigated and compared to the characteristics of 17 reference strains obtained from nonhuman sources. All of the S. porcinus isolates were beta-hemolytic (wide zones), susceptible to vancomycin, gave positive results for the leucine aminopeptidase and L-pyrrolidonylarylamidase tests, and produced acids from mannitol and sorbitol. Most of them were positive for the CAMP test and resistant to bacitracin. The isolates were susceptible to most of the 14 antimicrobials tested, except for tetracycline, for which 80% of the human isolates and 35.2% of the nonhuman strains were resistant. The tet(M) and the tet(O) genes were detected in 23 (88.5%) and 8 (30.8%) of the 26 tetracycline-resistant isolates, respectively. Analysis of whole-cell protein profiles obtained after sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a high similarity among the profiles. Chromosomal DNA was analyzed by pulsed-field gel electrophoresis (PFGE) after digestion with SmaI and by random(ly) amplified polymorphic DNA (RAPD)-PCR using primer 1254. Analysis of SmaI-restricted genomic DNA revealed the substantial genetic diversity among S. porcinus isolates from nonhuman sources, which were also serologically more diverse. Most of the human isolates belonged to serogroup NG1 and shared highly related PFGE profiles that were distinct from profiles of isolates from nonhuman sources. These results were in agreement with those obtained by analysis of amplicons after RAPD-PCR, indicating the potential ability of these techniques for typing S. porcinus and suggesting the occurrence of a few clonal groups of S. porcinus strains adapted to the human host.
Antimicrobial Agents and Chemotherapy, 2005
In the present report we describe the characteristics of 189 antimicrobial-resistant Streptococcu... more In the present report we describe the characteristics of 189 antimicrobial-resistant Streptococcus agalactiae isolates from bovine (38 isolates) and human (151 isolates) sources. All the strains were resistant to tetracycline (TET), and 16 (8.5%) were also resistant to erythromycin, corresponding to 23.7% of the TET-resistant bovine isolates and 4.6% of the TET-resistant human isolates. , and mreA resistance-related genes, as well as the bca and scpB virulence-related genes, were the most frequent among the bovine isolates, while the tet(M), erm(A), mreA, bca, lmb, and scpB genes were the most prevalent among the isolates from humans. Although a few major clusters were observed, pulsed-field gel electrophoresis results revealed a variety of profiles, reflecting the substantial genetic diversity among strains of this species isolated from either humans or bovines.
Ices Journal of Marine Science, 1997
P. 1997. Study of the growth of southern black and white monkfish stocks. -ICES Journal of Marine... more P. 1997. Study of the growth of southern black and white monkfish stocks. -ICES Journal of Marine Science, 54: 866-874.
Fisheries Research, 2001
The reproduction of black anglerfish (Lophius budegassa Spinola) and white anglerfish (Lophius pi... more The reproduction of black anglerfish (Lophius budegassa Spinola) and white anglerfish (Lophius piscatorius Linnaeus) has been studied from data collected between July 1996 and June 1997 off the Portuguese and Spanish Atlantic coasts at depths between 50 and 800 m. A total of 1301 black anglerfish (5–89 cm) and 1297 white anglerfish (11–129 cm) were sampled. The sex ratio, the spawning period and the maturity ogives by length and age were studied. The overall sex ratio was close to one for both species and the observed length related differences in sex ratio were explained by the different growth rate between sexes. The spawning period for black anglerfish was between November and February and for white anglerfish between January and June. The lengths and ages at first maturity for black anglerfish were 53.6 cm and 9–10 years for females, 38.6 cm and 7 years for males and 44.7 cm and 8 years for combined sexes. The lengths and ages at first maturity of white anglerfish were 93.9 cm and 14 years for females and 50.3 cm and 6 years for males. In this study no spawning white anglerfish females were sampled and the number of mature females was low for both species, suggesting a reproductive migration to other areas or depths.
Ices Journal of Marine Science, 2007
bottom trawl and gillnet commercial vessels and on trawl surveys, were tagged from 1995 to 2004; ... more bottom trawl and gillnet commercial vessels and on trawl surveys, were tagged from 1995 to 2004; 50 were recovered, and a growth rate of 13.6 cm year 21 was estimated from the four fish at liberty long enough to allow extrapolation of the growth rate to an annual period. Growth patterns were reviewed based on available studies of growth verification of white anglerfish in Atlantic waters, including another tag-recapture study, length-frequency of catches, and microstructure analysis of hard parts. The growth rate estimated from these studies showed many similarities, and an overall growth pattern was estimated: growth rate = 18.24e -0.015length . A von Bertalanffy growth curve fitted to all data yielded the parameter values L 1 = 140 cm and k = 0.11. This growth rate is faster than estimated recently using illicia for age estimation, but similar to that found in the first studies that used illicia and sectioned otoliths. Current estimates of growth based on illicia, which are used in assessing the northern European stock of white anglerfish, seem to be underestimated.
Journal of The World Aquaculture Society, 2010
Tambaqui, Colossoma macropomum, were fed with three vitamin C levels and two iron levels for 21 d... more Tambaqui, Colossoma macropomum, were fed with three vitamin C levels and two iron levels for 21 d: Diet 1 without vitamin C and with 30 mg of iron/kg; Diet 2 with 100 mg of vitamin C and 30 mg of iron/kg; and Diet 3 with 100 mg of vitamin C and 300 mg of iron/kg. Mortality was not observed during the feeding experiment. There were no changes in hematological parameters in fish that were fed the different diets. Iron contents in liver, muscle, and plasma were significantly different in fish fed with different iron content in the diets; when associated with vitamin C, changes were observed only for plasma iron. Therefore, tambaqui exhibits varied iron absorption in response to different levels of iron with and without vitamin C, a conclusion consistent with findings for other species of fish.
Progress in Organic Coatings, 2005
In this work, the protection conferred by Cr(VI)-containing and Cr-free pre-treatments and primer... more In this work, the protection conferred by Cr(VI)-containing and Cr-free pre-treatments and primers used in hot dip galvanized steel (HDG) coated systems were studied. The EIS results showed a differentiated behaviour for the specimens with Cr(VI) compared to the chromium-free ones. The samples with Cr(VI), both in the pre-treatment and in the primer, presented a better corrosion performance when compared to the Cr-free ones.Moreover, it can be said that the pre-treated and primed samples without Cr(VI) presented lower resistive properties and higher delamination fractions throughout the immersion time. The amount of Cr in the primer also influenced the coating resistance for shorter periods of immersion, but for long periods the passivating effect of Cr seems to be determinant.When topcoat was applied, i.e. for a complete system, the Cr-free specimens performed better than the Cr(VI)-containing ones, perhaps due to a better adhesion of the topcoat to the primer in the former case. This leads to the conclusion that there is a risk in assessing the behaviour of a paint scheme on the basis of the individual behaviour of each layer.
Progress in Organic Coatings, 2005
This work reports a comparative study on the corrosion resistance of AA2024-T3 pre-treated with t... more This work reports a comparative study on the corrosion resistance of AA2024-T3 pre-treated with three different silane solutions. The silanes used for the pre-treatments of the AA2024-T3 panels were: 1,2-bis(triethoxysilyl)ethane (BTSE), bis-[triethoxysilylpropyl]tetrasulfide (BTESPT) and γ-mercaptopropyltrimethoxysilane (γ-MPS). The analytical characterisation of the silane films was performed by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The corrosion performance of the pre-treated substrates was evaluated by electrochemical impedance spectroscopy (EIS). The results show that the pre-treatments based on silanes provide good corrosion protection of unpainted AA2024-T3. Painted substrates, previously pre-treated with the silane solutions also revealed improved corrosion resistance and good adhesion properties. Fatigue tests show that the silane pre-treatments do not affect the fatigue behaviour of the AA2024-T3. The work also discusses the formation of the protective silane films.
Corrosion Science, 2005
This work aims at studying the corrosion behaviour of AA2024-T3 pre-treated with bis-[triethoxysi... more This work aims at studying the corrosion behaviour of AA2024-T3 pre-treated with bis-[triethoxysilylpropyl]tetrasulphide. Simultaneously, the work investigates the influence of the Cu-rich intermetallic particles on the formation of the silane film. The analytical characterisation of the silane films was performed by Auger electron spectroscopy and X-ray photoelectron spectroscopy. The corrosion performance of the pre-treated substrates was evaluated by electrochemical impedance spectroscopy. Atomic force microscopy associated with Kelvin probe was also used to determine the influence of the silane film on the Volta potential distribution on the alloy surface. The results show that copper present in the intermetallics plays an important role on the film formation.
Progress in Organic Coatings, 2009
In this work, a new and more intricate model of estimate water uptake inside an organic coating b... more In this work, a new and more intricate model of estimate water uptake inside an organic coating by impedance measurements is proposed, the tortuosity pore model (TPM). In this model, the organic coating (film) is considered to be a ternary system, composed of liquid (solution), solid (coating matrix) and gas (air) phases. Moreover, the pores tortuosity inside the coating is taken into consideration. Comparison between this new model and the other models found in the literature will be presented, showing that this new model presents for water uptake better correlation with the values obtained by gravimetry.
Electrochimica Acta, 2004
Cr(VI)-based pre-treatments have been in use for long time on several materials, however, they ar... more Cr(VI)-based pre-treatments have been in use for long time on several materials, however, they are target of great criticism and in the near future they could be definitely banned. The actual alternatives to Cr(VI) show pros and cons when sets of key properties are considered such as: corrosion resistance, adhesion of organic coatings, fatigue resistance, reliability and quality control. However, some of the possible alternatives show high potential, if some improvements are carried out and the if mechanisms involved are more deeply understood.
This study evaluated the biodiversity of 28 clinical and 24 environmental Mycobacterium isolates ... more This study evaluated the biodiversity of 28 clinical and 24 environmental Mycobacterium isolates from Rio de Janeiro, Brazil, by using hsp65 sequences, with the aim of contributing to a better understanding of the genetic diversity and usefulness of this marker. An extensive phylogenetic analysis was performed. The nucleotide diversity was similar between clinical (0.06508) and environmental (0.06221) isolates.
This work presents a technique to estimate the parameters of the restoration filter more suitable... more This work presents a technique to estimate the parameters of the restoration filter more suitable for correction on CBERS-2 CCD images through data mining techniques.
Information on the characteristics of Streptococcus agalactiae obtained from bovine sources in Br... more Information on the characteristics of Streptococcus agalactiae obtained from bovine sources in Brazil is still very limited. The aim of this study was to assess the phenotypic and genotypic diversity among S. agalactiae isolates from milk of dairy cows presenting clinical or subclinical mastitis in the southeast region of Brazil. Phenotypic characterization was based on physiological and serological tests. Antimicrobial susceptibility tests were carried out by the disk method. Genetic diversity was evaluated by using random amplified polymorphic DNA-PCR (RAPD-PCR) (by using the primer 1254) and pulsed-field gel electrophoresis (PFGE) (by using SmaI as the restriction enzyme) and by PCRs for detection of genes associated with resistance to erythromycin and tetracycline as well as PCRs for detection of genes coding for cell surface-associated proteins. According to the results of physiologic tests, 45 (52.9%) isolates showed beta-hemolysis and 44 (51.7%) were susceptible to bacitracin. Fourteen different biotypes were detected. The two most frequent biotypes comprised strains that were non-beta-hemolytic; fermented galactose, lactose, and salicin; produced protease; and were negative for DNase production. Serotype III was predominant (66 isolates [77.6%]), followed by serotypes II, Ia, Ib, and VI. Resistance to tetracycline and erythromycin was found in 38 (44.7%) and 9 (10.5%) isolates, respectively, with tet(O) (31.7%) and erm(B) (100%) being the most frequently occurring resistance genes. Three genes coding for surface proteins, bca, lmb, and scpB, were detected in 55 (64.7%), 7 (8.2%), and 43 (50.5%) isolates, respectively. In most cases, isolates from animals in the same herd presented closely related genetic profiles (determined by either RAPD-PCR or PFGE), which were distinct from those of isolates from different herds.
The phenotypic and genotypic characteristics of 25 Streptococcus porcinus isolates recovered from... more The phenotypic and genotypic characteristics of 25 Streptococcus porcinus isolates recovered from human sources were investigated and compared to the characteristics of 17 reference strains obtained from nonhuman sources. All of the S. porcinus isolates were beta-hemolytic (wide zones), susceptible to vancomycin, gave positive results for the leucine aminopeptidase and L-pyrrolidonylarylamidase tests, and produced acids from mannitol and sorbitol. Most of them were positive for the CAMP test and resistant to bacitracin. The isolates were susceptible to most of the 14 antimicrobials tested, except for tetracycline, for which 80% of the human isolates and 35.2% of the nonhuman strains were resistant. The tet(M) and the tet(O) genes were detected in 23 (88.5%) and 8 (30.8%) of the 26 tetracycline-resistant isolates, respectively. Analysis of whole-cell protein profiles obtained after sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a high similarity among the profiles. Chromosomal DNA was analyzed by pulsed-field gel electrophoresis (PFGE) after digestion with SmaI and by random(ly) amplified polymorphic DNA (RAPD)-PCR using primer 1254. Analysis of SmaI-restricted genomic DNA revealed the substantial genetic diversity among S. porcinus isolates from nonhuman sources, which were also serologically more diverse. Most of the human isolates belonged to serogroup NG1 and shared highly related PFGE profiles that were distinct from profiles of isolates from nonhuman sources. These results were in agreement with those obtained by analysis of amplicons after RAPD-PCR, indicating the potential ability of these techniques for typing S. porcinus and suggesting the occurrence of a few clonal groups of S. porcinus strains adapted to the human host.
Antimicrobial Agents and Chemotherapy, 2005
In the present report we describe the characteristics of 189 antimicrobial-resistant Streptococcu... more In the present report we describe the characteristics of 189 antimicrobial-resistant Streptococcus agalactiae isolates from bovine (38 isolates) and human (151 isolates) sources. All the strains were resistant to tetracycline (TET), and 16 (8.5%) were also resistant to erythromycin, corresponding to 23.7% of the TET-resistant bovine isolates and 4.6% of the TET-resistant human isolates. , and mreA resistance-related genes, as well as the bca and scpB virulence-related genes, were the most frequent among the bovine isolates, while the tet(M), erm(A), mreA, bca, lmb, and scpB genes were the most prevalent among the isolates from humans. Although a few major clusters were observed, pulsed-field gel electrophoresis results revealed a variety of profiles, reflecting the substantial genetic diversity among strains of this species isolated from either humans or bovines.
Ices Journal of Marine Science, 1997
P. 1997. Study of the growth of southern black and white monkfish stocks. -ICES Journal of Marine... more P. 1997. Study of the growth of southern black and white monkfish stocks. -ICES Journal of Marine Science, 54: 866-874.
Fisheries Research, 2001
The reproduction of black anglerfish (Lophius budegassa Spinola) and white anglerfish (Lophius pi... more The reproduction of black anglerfish (Lophius budegassa Spinola) and white anglerfish (Lophius piscatorius Linnaeus) has been studied from data collected between July 1996 and June 1997 off the Portuguese and Spanish Atlantic coasts at depths between 50 and 800 m. A total of 1301 black anglerfish (5–89 cm) and 1297 white anglerfish (11–129 cm) were sampled. The sex ratio, the spawning period and the maturity ogives by length and age were studied. The overall sex ratio was close to one for both species and the observed length related differences in sex ratio were explained by the different growth rate between sexes. The spawning period for black anglerfish was between November and February and for white anglerfish between January and June. The lengths and ages at first maturity for black anglerfish were 53.6 cm and 9–10 years for females, 38.6 cm and 7 years for males and 44.7 cm and 8 years for combined sexes. The lengths and ages at first maturity of white anglerfish were 93.9 cm and 14 years for females and 50.3 cm and 6 years for males. In this study no spawning white anglerfish females were sampled and the number of mature females was low for both species, suggesting a reproductive migration to other areas or depths.
Ices Journal of Marine Science, 2007
bottom trawl and gillnet commercial vessels and on trawl surveys, were tagged from 1995 to 2004; ... more bottom trawl and gillnet commercial vessels and on trawl surveys, were tagged from 1995 to 2004; 50 were recovered, and a growth rate of 13.6 cm year 21 was estimated from the four fish at liberty long enough to allow extrapolation of the growth rate to an annual period. Growth patterns were reviewed based on available studies of growth verification of white anglerfish in Atlantic waters, including another tag-recapture study, length-frequency of catches, and microstructure analysis of hard parts. The growth rate estimated from these studies showed many similarities, and an overall growth pattern was estimated: growth rate = 18.24e -0.015length . A von Bertalanffy growth curve fitted to all data yielded the parameter values L 1 = 140 cm and k = 0.11. This growth rate is faster than estimated recently using illicia for age estimation, but similar to that found in the first studies that used illicia and sectioned otoliths. Current estimates of growth based on illicia, which are used in assessing the northern European stock of white anglerfish, seem to be underestimated.