Renata Barbosa | Universidade de Marília (original) (raw)
Papers by Renata Barbosa
Biological Trace Element Research
The placenta is fundamental for fetal development. The aim of this study was to determine Ca, Fe,... more The placenta is fundamental for fetal development. The aim of this study was to determine Ca, Fe, Cu, and Zn content in the fetal and maternal portions of the placentas of teenage and adult women. Measurement of the minerals was conducted using Synchrotron radiation total reflection X-ray fluorescence. Forty samples from the fetal portion of teenagers and adults and 40 samples from the maternal portion of teenagers and adults were analyzed. There were significant differences in the Ca and Cu concentrations of the placenta’s maternal portion when compared to the fetal portion, for both teenagers and adults. There were differences in Fe and Zn concentrations only when comparing the maternal portion of placenta with the fetal portion of the adults. These results suggest important differences in mineral content based on the placental portion. No significant difference was observed between the minerals studied of the maternal portion of teenagers and adults; however, in the fetal portion, mineral concentrations were greater in adults than in teenagers. Therefore, the mineral concentration of the fetal portion of the placenta is influenced by the mother’s age. If there is mineral’s competition between the mother and fetus during pregnancy in adolescence due to the importance of these minerals in growth and development, then the mechanism and reason for it should be elucidated in future research. In addition, we believe that further research should be carried out on transporters of these minerals in the same portions of the placentas analyzed by our group, in teenagers and adults.
Biological Trace Element Research, 2011
Adolescence is marked by intensive growth and development. When pregnancy occurs during this peri... more Adolescence is marked by intensive growth and development. When pregnancy occurs during this period of the mother’s growth, there is an increase in her nutritional needs. The aim of this study was to determine the levels of calcium, iron, copper, and zinc in maternal plasma, the placenta, and in the cord plasma of pregnant teenagers and adults. A total of 80 sets of maternal plasma, placentas, and cord plasma (40 from teenagers and 40 from adults) were analyzed using synchrotron radiation total reflection X-ray fluorescence. The levels of calcium, copper, and zinc in the maternal and cord plasma from teenagers were not significantly different than those from adults. Iron levels in the teenagers maternal and cord plasma were higher than in the adults. All of the minerals analyzed were present at higher levels in the placentas from adults than those from teenagers. However, the low quantities of placental calcium, iron, copper, and zinc in the teenagers do not compromise the levels of these minerals in the cord plasma. Future research regarding the placental transport of these minerals is recommended to investigate the efficiency of mechanisms of transfer of these minerals in pregnant teenagers.
Oxford Economic Papers-new Series, 2008
This paper uses a unique data set of Latin American paintings auctioned by Sotheby's between 1995... more This paper uses a unique data set of Latin American paintings auctioned by Sotheby's between 1995 and 2002 to investigate several puzzles from the recent auctions literature. Our results suggest that: (1) the reputation of an artist and the provenance of the artwork, omitted variables in most previous studies, seem to be more important determinants of the sale price of a painting than standard factors, such as medium and size, (2) the opinion of art experts seems to be of limited use in predicting whether or not an artwork sells at auction, (3) there is little supporting evidence for the widespread notion that the best or more expensive artworks tend to generate above average returns (the "masterpiece effect"), although (4) there is strong evidence in our data for the declining price anomaly, or "afternoon effect." JEL Classification: D44, G11, L12, Z10
Materials Letters, 2007
Polyethylene (PE)/Brazilian clay nanocomposites and PE/commercial flame retardant systems were pr... more Polyethylene (PE)/Brazilian clay nanocomposites and PE/commercial flame retardant systems were produced via direct melt intercalation. A montmorillonite sample from the Brazilian state of Paraíba was organically modified with esthearildimethylammonium chloride (Praepagen) quaternary ammonium salt and has been tested to be used in polymer nanocomposites. The dispersion analysis and the interlayer distance of the clay particles were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The flammability behavior of the obtained systems was investigated by horizontal burning tests for HB classification, Underwriters Laboratories (UL94). It was observed that the burning rate of PE/Brazilian clay nanocomposites was significantly reduced in relation to pure PE and PE/flame retardant systems, indicating that the PE/Brazilian clay system was more efficient.
Objetivo: Traçar a trajetória percorrida por uma equipe multiprofissional em um projeto de interv... more Objetivo: Traçar a trajetória percorrida por uma equipe multiprofissional em um projeto de intervenção realizado com crianças desnutridas de 1 a 5 anos e suas famílias. Métodos: Trabalho de natureza quantitativa realizado com um universo de 165 crianças, sob responsabilidade de uma Equipe de Saúde da Família (ESF) da periferia do município de São Paulo. As variáveis estudadas foram: os dados socioeconômicos familiares, avaliação do consumo alimentar, triagem de desenvolvimento e classificação do estado nutricional por escore Z. Com base nesses dados, planejaram-se atividades de intervenção, que envolveram oficinas educativas sobre a saúde infantil, oficinas culinárias e visitas domiciliares. Resultados: Os aspectos socioeconômicos refletiam baixa renda familiar, com média de 6 anos de estudo, consumo alimentar inadequado e 53 (32,1%) encontravam-se desnutridas. A triagem de desenvolvimento mostrou 33(62,3%) crianças em situação de risco, com maior comprometimento na área da linguagem. Conclusão: Para a execução de intervenções em saúde é primordial conhecer a comunidade em que se está inserido, pois somente desta forma é possível se aproximar das reais necessidades e estabelecer estratégias nutricionais mais adequadas, que favoreçam a autonomia e a responsabilidade dos indivíduos para o cuidado com a saúde.
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007
Nanocomposites containing polyethylene (PE) and montmorillonite clay organically modified (OMMT) ... more Nanocomposites containing polyethylene (PE) and montmorillonite clay organically modified (OMMT) with quaternary ammonium salts were obtained via direct melt intercalation. A montmorillonite sample from the Brazilian state of Paraíba was treated with four different types of quaternary ammonium salts. After the treatment, the powder was characterized by X-ray diffraction and scanning electron microscopy. The dispersion and morphologies of OMMT within PE were investigated by X-ray diffraction and transmission electron microscopy. The results revealed the formation of intercalated montmorillonite layers in the PE matrix. The thermal stability and flammability of the PE/montmorillonite clay nanocomposites were measured by thermogravimetry and horizontal burning tests for HB classification, Underwrites Laboratories (UL 94), respectively. It was shown that the samples do not degrade at the processing temperature. By adding only 3 wt.% montmorillonite, the burning rate of the nanocomposites was reduced by 17%, and, in general, the tensile test showed that the yield strength and modulus of the nanocomposites are close to the pure PE. However, for a selected salt for MMT treatment the mechanical properties of nanocomposites were improved.
Journal of Thermal Analysis and Calorimetry, 2007
Nanocomposites containing both polyethylene and montmorillonite clay organically modified with fo... more Nanocomposites containing both polyethylene and montmorillonite clay organically modified with four different types of quaternary ammonium salts were obtained via direct melt intercalation. Thus, the main purpose of this work was to evaluate the effect of the organoclay on the thermal stability of polyethylene. The organoclays were characterized by XRD, FTIR, DSC and TG. The polyethylene/organoclay nanocomposites were studied by XRD, TEM, TG, besides an evaluation of their mechanical properties. The results showed that the salts were incorporated by intercalation between the layers of the organoclay and, apparently that the nanocomposites were more thermally stable than pure polyethylene.
Materials Science Forum, 2006
In this work, (nano)composites of polyethylene/bentonite clay were produced with 5wt.% of clay. T... more In this work, (nano)composites of polyethylene/bentonite clay were produced with 5wt.% of clay. The clays were treated with quaternary salts of ammonium and then treated and untreated clays were introduced in polyethylene by melt intercalation. The clays were characterized by X-Ray Diffraction (XRD) and Infrared (FT-IR). The (nano)composites were characterized by mechanical and flammability properties. The results showed that the mechanical properties were improved by introduction of organoclay in polyethylene matrix. By adding only 3wt% organoclay was observed that the burning rate of the nanocomposites was reduced by 17% in relation to PE matrix.
Journal of Thermal Analysis and Calorimetry, 2007
Polyethylene/montmorillonite clay nanocomposites were obtained via direct melt intercalation. The... more Polyethylene/montmorillonite clay nanocomposites were obtained via direct melt intercalation. The clay was organically modified with four different types of quaternary ammonium salts. The objective of this work is to study the use of montmorillonite clay in the production of nanocomposites by means on rheological, mechanical and crystallization properties of nanocomposites and to compare to the properties of the matrix and PE/unmodified clay nanocomposites. In general, the tensile test showed that the yield strength and modulus of the nanocomposites are close to the pure PE. Apparently, the mixture with Dodigen salt seems to be more stable than the pure PE and PE/unmodified clay.
Biological Trace Element Research
The placenta is fundamental for fetal development. The aim of this study was to determine Ca, Fe,... more The placenta is fundamental for fetal development. The aim of this study was to determine Ca, Fe, Cu, and Zn content in the fetal and maternal portions of the placentas of teenage and adult women. Measurement of the minerals was conducted using Synchrotron radiation total reflection X-ray fluorescence. Forty samples from the fetal portion of teenagers and adults and 40 samples from the maternal portion of teenagers and adults were analyzed. There were significant differences in the Ca and Cu concentrations of the placenta’s maternal portion when compared to the fetal portion, for both teenagers and adults. There were differences in Fe and Zn concentrations only when comparing the maternal portion of placenta with the fetal portion of the adults. These results suggest important differences in mineral content based on the placental portion. No significant difference was observed between the minerals studied of the maternal portion of teenagers and adults; however, in the fetal portion, mineral concentrations were greater in adults than in teenagers. Therefore, the mineral concentration of the fetal portion of the placenta is influenced by the mother’s age. If there is mineral’s competition between the mother and fetus during pregnancy in adolescence due to the importance of these minerals in growth and development, then the mechanism and reason for it should be elucidated in future research. In addition, we believe that further research should be carried out on transporters of these minerals in the same portions of the placentas analyzed by our group, in teenagers and adults.
Biological Trace Element Research, 2011
Adolescence is marked by intensive growth and development. When pregnancy occurs during this peri... more Adolescence is marked by intensive growth and development. When pregnancy occurs during this period of the mother’s growth, there is an increase in her nutritional needs. The aim of this study was to determine the levels of calcium, iron, copper, and zinc in maternal plasma, the placenta, and in the cord plasma of pregnant teenagers and adults. A total of 80 sets of maternal plasma, placentas, and cord plasma (40 from teenagers and 40 from adults) were analyzed using synchrotron radiation total reflection X-ray fluorescence. The levels of calcium, copper, and zinc in the maternal and cord plasma from teenagers were not significantly different than those from adults. Iron levels in the teenagers maternal and cord plasma were higher than in the adults. All of the minerals analyzed were present at higher levels in the placentas from adults than those from teenagers. However, the low quantities of placental calcium, iron, copper, and zinc in the teenagers do not compromise the levels of these minerals in the cord plasma. Future research regarding the placental transport of these minerals is recommended to investigate the efficiency of mechanisms of transfer of these minerals in pregnant teenagers.
Oxford Economic Papers-new Series, 2008
This paper uses a unique data set of Latin American paintings auctioned by Sotheby's between 1995... more This paper uses a unique data set of Latin American paintings auctioned by Sotheby's between 1995 and 2002 to investigate several puzzles from the recent auctions literature. Our results suggest that: (1) the reputation of an artist and the provenance of the artwork, omitted variables in most previous studies, seem to be more important determinants of the sale price of a painting than standard factors, such as medium and size, (2) the opinion of art experts seems to be of limited use in predicting whether or not an artwork sells at auction, (3) there is little supporting evidence for the widespread notion that the best or more expensive artworks tend to generate above average returns (the "masterpiece effect"), although (4) there is strong evidence in our data for the declining price anomaly, or "afternoon effect." JEL Classification: D44, G11, L12, Z10
Materials Letters, 2007
Polyethylene (PE)/Brazilian clay nanocomposites and PE/commercial flame retardant systems were pr... more Polyethylene (PE)/Brazilian clay nanocomposites and PE/commercial flame retardant systems were produced via direct melt intercalation. A montmorillonite sample from the Brazilian state of Paraíba was organically modified with esthearildimethylammonium chloride (Praepagen) quaternary ammonium salt and has been tested to be used in polymer nanocomposites. The dispersion analysis and the interlayer distance of the clay particles were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The flammability behavior of the obtained systems was investigated by horizontal burning tests for HB classification, Underwriters Laboratories (UL94). It was observed that the burning rate of PE/Brazilian clay nanocomposites was significantly reduced in relation to pure PE and PE/flame retardant systems, indicating that the PE/Brazilian clay system was more efficient.
Objetivo: Traçar a trajetória percorrida por uma equipe multiprofissional em um projeto de interv... more Objetivo: Traçar a trajetória percorrida por uma equipe multiprofissional em um projeto de intervenção realizado com crianças desnutridas de 1 a 5 anos e suas famílias. Métodos: Trabalho de natureza quantitativa realizado com um universo de 165 crianças, sob responsabilidade de uma Equipe de Saúde da Família (ESF) da periferia do município de São Paulo. As variáveis estudadas foram: os dados socioeconômicos familiares, avaliação do consumo alimentar, triagem de desenvolvimento e classificação do estado nutricional por escore Z. Com base nesses dados, planejaram-se atividades de intervenção, que envolveram oficinas educativas sobre a saúde infantil, oficinas culinárias e visitas domiciliares. Resultados: Os aspectos socioeconômicos refletiam baixa renda familiar, com média de 6 anos de estudo, consumo alimentar inadequado e 53 (32,1%) encontravam-se desnutridas. A triagem de desenvolvimento mostrou 33(62,3%) crianças em situação de risco, com maior comprometimento na área da linguagem. Conclusão: Para a execução de intervenções em saúde é primordial conhecer a comunidade em que se está inserido, pois somente desta forma é possível se aproximar das reais necessidades e estabelecer estratégias nutricionais mais adequadas, que favoreçam a autonomia e a responsabilidade dos indivíduos para o cuidado com a saúde.
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007
Nanocomposites containing polyethylene (PE) and montmorillonite clay organically modified (OMMT) ... more Nanocomposites containing polyethylene (PE) and montmorillonite clay organically modified (OMMT) with quaternary ammonium salts were obtained via direct melt intercalation. A montmorillonite sample from the Brazilian state of Paraíba was treated with four different types of quaternary ammonium salts. After the treatment, the powder was characterized by X-ray diffraction and scanning electron microscopy. The dispersion and morphologies of OMMT within PE were investigated by X-ray diffraction and transmission electron microscopy. The results revealed the formation of intercalated montmorillonite layers in the PE matrix. The thermal stability and flammability of the PE/montmorillonite clay nanocomposites were measured by thermogravimetry and horizontal burning tests for HB classification, Underwrites Laboratories (UL 94), respectively. It was shown that the samples do not degrade at the processing temperature. By adding only 3 wt.% montmorillonite, the burning rate of the nanocomposites was reduced by 17%, and, in general, the tensile test showed that the yield strength and modulus of the nanocomposites are close to the pure PE. However, for a selected salt for MMT treatment the mechanical properties of nanocomposites were improved.
Journal of Thermal Analysis and Calorimetry, 2007
Nanocomposites containing both polyethylene and montmorillonite clay organically modified with fo... more Nanocomposites containing both polyethylene and montmorillonite clay organically modified with four different types of quaternary ammonium salts were obtained via direct melt intercalation. Thus, the main purpose of this work was to evaluate the effect of the organoclay on the thermal stability of polyethylene. The organoclays were characterized by XRD, FTIR, DSC and TG. The polyethylene/organoclay nanocomposites were studied by XRD, TEM, TG, besides an evaluation of their mechanical properties. The results showed that the salts were incorporated by intercalation between the layers of the organoclay and, apparently that the nanocomposites were more thermally stable than pure polyethylene.
Materials Science Forum, 2006
In this work, (nano)composites of polyethylene/bentonite clay were produced with 5wt.% of clay. T... more In this work, (nano)composites of polyethylene/bentonite clay were produced with 5wt.% of clay. The clays were treated with quaternary salts of ammonium and then treated and untreated clays were introduced in polyethylene by melt intercalation. The clays were characterized by X-Ray Diffraction (XRD) and Infrared (FT-IR). The (nano)composites were characterized by mechanical and flammability properties. The results showed that the mechanical properties were improved by introduction of organoclay in polyethylene matrix. By adding only 3wt% organoclay was observed that the burning rate of the nanocomposites was reduced by 17% in relation to PE matrix.
Journal of Thermal Analysis and Calorimetry, 2007
Polyethylene/montmorillonite clay nanocomposites were obtained via direct melt intercalation. The... more Polyethylene/montmorillonite clay nanocomposites were obtained via direct melt intercalation. The clay was organically modified with four different types of quaternary ammonium salts. The objective of this work is to study the use of montmorillonite clay in the production of nanocomposites by means on rheological, mechanical and crystallization properties of nanocomposites and to compare to the properties of the matrix and PE/unmodified clay nanocomposites. In general, the tensile test showed that the yield strength and modulus of the nanocomposites are close to the pure PE. Apparently, the mixture with Dodigen salt seems to be more stable than the pure PE and PE/unmodified clay.