Influência da secagem, armazenamento e embalagem nos resultados da análise química de terra para fins de fertilidade

Amostras de terra provenientes de uma Terra Roxa Estruturada e um Latossol Vermelho Escuro textura média foram analisados quimicamente para se verificar a influência de embalagem (caixa de papelão saco de polietileno), tempo de armazenamento (1-32 dias) e processo de secagem (ao ar ou estufa a 60°C). A secagem foi o fator que mais influenciou a análise determinando variações nos resultados analíticos principalmente para pH e fósforo. O armazenamento apresentou influência apenas para fósforo trocável enquanto que a embalagem não influiu nos resultados. As variações dos resultados analíticos para pH, em função da secagem, e fósforo, em função da secagem e tempo de armazenamento, foram de ordem a alterar a interpretação da fertilidade quanto aos limites de classes.

EMBALAGEM INDIVIDUAL DE MANGAS CV. TOMMY ATKINS em FILME PLÁSTICO: EFEITO SOBRE A VIDA DE PRATELEIRA

Estudou-se o efeito da embalagem de policloreto de vinila (PVC) sobre a vida de prateleira de mangas cv. Tommy Atkins armazenadas sob refrigeração. Mangas no estádio de maturidade fisiológica, com casca verde ou levemente avermelhada, foram embaladas individualmente, com filme de 10mm de espessura, e armazenadas por 28 dias a 12ºC (80-90% UR). Frutos sem embalagem serviram de controle. Durante o período de armazenagem, foram feitas avaliações sensoriais utilizando o método de escala hedônica não estruturada para aceitação da aparência e do sabor, utilizando-se de 30 provadores não treinados por sessão. Determinou-se também a perda de massa, a acidez titulável e os teores de sólidos solúveis e vitamina C ao longo da armazenagem. As mangas embaladas apresentaram uma vida de prateleira de 21 dias contra 6 dias das não embaladas, e uma taxa de perda de massa 3,5 vezes menor que as não embaladas. em relação à taxa de degradação de vitamina C, não houve diferença entre os tratamentos. A combinação da embalagem com a armazenagem a 12ºC aumentou a vida de prateleira do produto pela redução da atividade metabólica e do desenvolvimento de podridão.

Otimização e validação de metodologia cromatográfica para determinação simultânea de composição monomérica em polímero biodegradável

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estimativa da composição gasosa em embalagem de atmosfera modificada contendo mangas (mangifera indica l.) Cv. Keitt

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Development and applications of three-dimensional gamma ray tomography system using ray casting volume rendering techniques

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evaluation of shear bond strength at the interface of two porcelains and pure titanium injected into the casting mold at three different temperatures

Statement of problem. Titanium has physical and mechanical properties, which have led to its increased use in dental prostheses despite casting difficulties due to high melting point and formation of oxide layers which affect the metal-ceramic bond strength.Purpose. This in vitro study evaluated the shear bond strength of the interface of 2 dental porcelains and pure titanium injected into a mold at 3 different temperatures.Material and methods. Using commercially pure (cp) titanium bars (Titanium, Grade I) melted at 1668degreesC and cast at mold temperatures of 430degreesC, 700degreesC or 900degreesC, 60 specimens were machined to 4 x 4 mm, with a base of 5 x 1 mm. The 4-mm surfaces were airborne-particle abraded with 100 mum aluminum oxide before applying and firing the bonding agent and evaluating the 2 porcelains (Triceram/Triline ti and Vita Titankeramik). Ten specimens were prepared for each temperature and porcelain combination Shear bond testing was performed in a universal testing machine, with a 500-kg load cell and crosshead speed of 0.5 mm/min. The specimens were loaded until failure. The interfaces of representative fractured specimens of each temperature were examined with a scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Data for shear bond strength (MPa) were statistically analyzed by 2-way ANOVA and the Tukey test (alpha = .05).Results. The results showed significant differences for the metal/porcelain interaction effect (P = .0464). There were no significant differences for the 2 porcelains (P = .4250). The Tukey test showed a significant difference between the pair cp Ti 430degreesC Triceram and cp Ti 900degreesC Triceram, with respective mean values and SDs of 59.74 +/- 11.62 and 34.03 +/- 10.35 MPa.Conclusion. Triceram porcelain showed a bond strength decrease with an increase in the mold temperature for casting titanium. The highest bond strength for Vita porcelain and the best metal-ceramic interface observed with the SEM were found with the mold temperature of 700degreesC.

Sintering of zirconia composites obtained by slip casting

Composites containing a matrix of nanometric Ce-stabilized zirconia with an addition of micrometric monoclinic zirconia were processed by slip casting and sintered at a relatively low temperature. The ratio between nanometric and micrometric particles was determined according to the viscosity of the suspensions and the final density of the pellets. An optimum amount of micrometric particles was necessary to achieve improved suspension dispersion and higher pellet density. The amount of deflocculant in the suspensions containing the mixture of micrometric and nanometric particles was optimized by viscosity measurements. The pellets were characterized by dilatometry, Hg porosimetry, density measurement (the Archimedes method) and scanning electron microscopy. Despite the low green density obtained (35-38% of the theoretical density), densities as high as 97.5% were achieved after sintering. (C) 2001 Elsevier B.V. Ltd and Techna S.r.l. All rights reserved.

Validação de métodos para determinação do teor de 3-hidroxibutirato e 3-hidroxivalerato em polímero biodegradável

The efficiency of two methods for determining 3-hydroxybutyrate and 3-hydroxyvalerate content in the biopolymer (poly(3-hydroxybutyrate-co-3-hydroxyvalerate) has been evaluated. Both methods are based on (a) the hydrolysis of polymers, (b) the esterification with methyl (method A) and isoamilic alcohol (method B) and (c) analysis of the esters by gas chromatography using flame ionization detection (GC-FID). After optimization of the analytical conditions, the main validation parameters (linearity, quantification limit, detection limit, recovery, sensitivity and precision) were determined showing that both analytical procedures can be applied to control the process of poly(3-hydroxybutyrate) production. However, method B gives better analytical results than method A and has the advantage of not using chlorinated solvents.

Sintering of tin oxide processed by slip casting

Sintering of SnO 2 compacts, obtained through slip casting, was studied by means of dilatometry, Hg porosimetry, scanning electron microscopy, and density measurement (Archimedes method). Sintering is strongly influenced by the green microstructure. Moreover, the sintering mechanisms are not dependent on the slurries' solid content up to 50% of solids in volume. Above this value, agglomerates are formed, leading to differential sintering inside and among the agglomerates. Another important point is the reduction of the temperature of maximum shrinkage rate when compared to tin oxide processed by isostatic pressing. This reduction is more accentuated when ammonium hydroxide is added to the suspension. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.

Aderência e formação do biofilme por Staphylococcus aureus ao polietilenotereftalato (PET) usado como embalagem para acondionamento de medicamentos e cosméticos

The polyethylene terephthalate (PET) is used for package drugs and cosmetics. The aim of this research was examine by scanning electron microscopy (SEM) a Staphylococcus aureus attachment and biofilm formation on a polyethylene terephthalate (PET) surface and hydrophobicity of S. aureus by adherence to hydrocarbons. A suspension of S. aureus was prepared in Mueller-Hinton broth and, coupons of polyethylene terephthalate were incubated for 30 minutes, two, 24 and 48 hours, 15 and 30 days. Afteron the coupons were removed and prepared for scanning electron microscope analysis. The attachment and biofilm formation was observed on the surfaces of PET. The SEM revealed adhesion and biofilm formation on PET surfaces. The hydrophobicity test classified S. aureus as hydrophobic.

In vitro comparisons of casting retention on implant abutments among commercially available and experimental castor oil-containing dental luting agents

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Produção otimizada de alginato e plástico biodegradável (poli-hidroxibutirato) por Azotobacter vinelandii

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Embalagem para produtos da fruticultura: uma reflexão em torno de norma, matéria, forma e uso das embalagens para fruticultura na sociedade contemporânea

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)