Variations in tree community composition and structure in a fragment of tropical semideciduous forest in southeastern Brazil related to different human disturbance histories

In an area of tropical seasonal semideciduous forest, the soil characteristics, floristic composition, physiognomic structure, and the distribution of three regeneration and three dispersal guilds were studied for four stands within the forest that had documented histories of varying degrees of human disturbance. The aim was to study forest regeneration in areas of preserved forest and secondary forest, with parts of both types of forest experiencing either 'intensive' or 'occasional' cattle trampling. The study was carried out in the Sebastiao Aleixo da Silva Ecological Station, Bauru, São Paulo State, Brazil. Two stands were called 'secondary' because they corresponded to forest tracts that were felled and occupied by crops and pastures in the past and then abandoned to forest regeneration ca. 40 years before this study. The other two stands, called 'preserved', corresponded to areas of the fragment where the forest has been maintained with only minor human impacts. The arboreal component of the tree community (diameter at breast height or dbh greater than or equal to 5 cm) was sampled in 20 plots of 40 m x 40 m, and the subarboreal component (diameter at the base of the stem or dbs < 5 cm and height greater than or equal to 0.5 m) in subplots of 40 m x 2 m. Physiognomic features, such as canopy height and density of climbing plants, were registered all over a 5 m x 5 m gridline laid on the sample plots. Soil bulk samples were collected for chemical and textural analyses. Most detected differences contrasted the secondary to the preserved forest stands. The soils of the secondary stands showed higher proportions of sand and lower levels of mineral nutrients and organic matter than those of the preserved stands, probably due to higher losses by leaching and erosion. Compared to the secondary stands, the preserved ones had higher proportions of tall trees, higher mean canopy height, lower species diversity, higher abundance of autochorous and shade-tolerant climax species, and lower abundance of pioneer and light-demanding climax species. Despite the high proportion of species shared by the preserved and secondary stands (108 out of 139), they differed consistently in terms of density of the most abundant species. on the other hand, the secondary and preserved stands held similar values for tree density and basal area, suggesting that 40 years were enough to restore these features. Effects of cattle trampling on the vegetation were detected for the frequency of trees of anemochorous and zoochorous species, which were higher in the stands under occasional and intensive cattle trampling, respectively. The density of thin climbers was lower in the stands with intensive trampling. (C) 2004 Elsevier B.V. All rights reserved.

Biomass production and chemical composition of Lippia alba (Mill.) NEBr. ex Britt & Wilson in leaves on different plant parts in different seasons

Lippia alba, family Verbenaceae, is widely spread in Central and South American. It's a shurb with a quadrangular branch reaching 1,7m tall. The leaves are membranaceous, petiolate, pubescent with a strong flavor. It's limbs have variable forms with pointed apex, cuneiform or decumbent base, and serrated or crenated hordes. It was determined the best harvest season to biomass production, essential oil content and chemical composition, on different plant parts (apical, medium, basal). It has been observed that, both apical and medium parts represented around 80 % of the fresh leaf mass. The foliar biomass yields are about 5 ton/ha in four harvests during an year. The average yield of essential oil considering the three plant parts were 0.15%, 0.47%, 0.46%, 0.55% and 0.61% for summer/98, autumn/98, winter/98, spring/98 and summer/99, respectively. Essential oils showed similar chemical composition either in relation to seasonality, neral, geranial and t-cariofilene were the majority compounds.

Effect of post-polymerization heat treatments on the cytotoxicity of two denture base acrylic resins

Introduction: Most denture base acrylic resins have polymethylmethacrylate in their composition. Several authors have discussed the polymerization process involved in converting monomer into polymer because adequate polymerization is a crucial factor in optimizing the physical properties and biocompatibility of denture base acrylic resins. To ensure the safety of these materials, in vitro cytotoxicity assays have been developed as preliminary screening tests to evaluate material biocompatibility. 3H-thymidine incorporation test, which measures the number of cells synthesizing DNA, is one of the biological assays suggested for cytotoxicity testing. Aim: The purpose of this study was to investigate, using 3H-thymidine incorporation test, the effect of microwave and water-bath post-polymerization heat treatments on the cytotoxicity of two denture base acrylic resins. Materials and Methods: Nine disc-shaped specimens (10 x 1 mm) of each denture base resin (Lucitone 550 and QC 20) were prepared according to the manufacturers' recommendations and stored in distilled water at 37°C for 48 h. The specimens were assigned to 3 groups: 1) post-polymerization in a microwave oven for 3 min at 500 W; 2) post-polymerization in water-bath at 55°C for 60 min; and 3) without post-polymerization. For preparation of eluates, 3 discs were placed into a sterile glass vial with 9 mL of Eagle's medium and incubated at 37°C for 24 h. The cytotoxic effect of the eluates was evaluated by 3H-thymidine incorporation. Results: The results showed that the components leached from the resins were cytotoxic to L929 cells, except for the specimens heat treated in water bath (p<0.05). Compared to the group with no heat treatment, water-bath decreased the cytotoxicity of the denture base acrylic resins. Conclusion: The in vitro cytotoxicity of the tested denture base materials was not influenced by microwave post-polymerization heat treatment.

In vitro adhesion of Candida glabrata to denture base acrylic resin modified by glow-discharge plasma treatment

This study evaluated the potential of plasma treatments to modify the surface chemistry and hydrophobicity of a denture base acrylic resin to reduce the Candida glabrata adhesion. Specimens (n=54) with smooth surfaces were made and divided into three groups (n=18): control - non-treated; experimental groups - submitted to plasma treatment (Ar/50W; AAt/130W). The effects of these treatments on chemical composition and surface topography of the acrylic resin were evaluated. Surface free energy measurements (SFE) were performed after the treatments and after 48h of immersion in water. For each group, half (n=9) of the specimens were preconditionated with saliva before the adhesion assay. The number of adhered C. glabrata was evaluated by cell counting after crystal violet staining. The Ar/50W and AAt/130W treatments altered the chemistry composition, hydrophobicity and topography of acrylic surface. The Ar/50W group showed significantly lower C. glabrata adherence than the control group, in the absence of saliva. After preconditioning with saliva, C. glabrata adherence in experimental and control groups did not differ significantly. There were significant changes in the SFE after immersion in water. The results demonstrated that Ar/50W treated surfaces have potential for reducing C. glabrata adhesion to denture base resins and deserve further investigation, especially to tailor the parameters to prolong the increased wettability. © 2012 Blackwell Verlag GmbH.

Predictive formulas for food base excess and urine pH estimations of cats

Food base excess (BE, mEq/kg) can be calculated from the diet macroelements, together with either the sulfur amino acids methionine and cysteine (BEaa) or total sulfur (BEs) concentrations. The present study compared the use of sulfur or methionine and cysteine for calculating the food BE (experiment 1) and investigated the influence of food BE on blood gas analysis and the urine pH of cats, and proposes a prediction equation to estimate the urine pH of cats fed kibble diets based on the calculated food BE (experiments 2 and 3). In experiment 1, nine healthy, adult cats were used in a change-over design and fed with nine commercial dry cat foods. The cats were housed in metabolism cages over seven days for adaptation and three days for total urine collection. All of the urine produced over 24h was pooled by cat and diet. The cats' acid-base status was assessed through blood gas analysis after 10 days of diet consumption. A mean difference of -115mEq/kg between BEs and BEaa was observed, which could be explained by a greater concentration of sulfur in the whole diet than in methionine and cysteine. Urine pH presented a stronger correlation with food BEs (R2=0.95; P<0.001) than with food BEaa (R2=0.86; P<0.001). Experiment 2 included 30 kibble diets, and each diet was tested in six cats. The food BEs varied between -180 and +307mEq/kg, and the urine pH of the cats varied between 5.60 and 7.74. A significant correlation was found between the measured urine pH and the food BEs (urinary pH=6.269+[0.0036×BEs]+[0.000003×BEs2]; R2=0.91; P<0.001). In experiment 3, eight kibble diets were tested (food BEs between -187mEq/kg and +381mEq/kg) to validate the equation proposed in experiment 2 and to compare the obtained results with previously published formulae. The results of the proposed formula presented a high concordance correlation coefficient (0.942) and high accuracy (0.979) with the measured values, and the estimates of urine pH did not differ from the values obtained in cats (P>0.05). The cats' venous blood pH, bicarbonate, and blood BE were correlated with food BEs (P<0.001); the consumption of diets with low food BEs induced a reduction in these parameters. In conclusion, food macroelement composition has a strong influence on cats' acid-base equilibrium and food BEs calculation is a useful tool to formulate and balance kibble diets for felines. © 2013 Elsevier B.V.

Desenvolvimento de produto tipo “snack” a base de carne mecanicamente separada de tilápia do Nilo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Desenvolvimento e avaliação em simulador do ecossistema microbiano humano de uma bebida simbiótica à base de extratos aquosos de quinoa (chenopodium quinoa willd) e de soja

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

Preparação de espuma cerâmica à base de zircônia pelo processo sol-emulsão-gel

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo da usinagem em torneamento da superliga a base de niquel NIMONIC 80

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeito da fadiga cíclica na resistência, crescimento subcrítico de trincas e tempo de vida de cerâmicas a base de alumina infiltradas por vidro

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Incorporação do metacrilato 2-tert-butilaminoetil a uma resina acrílica para a base protética: caracterização química e efeito sobre a resistência flexural

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

O emprego na transição para uma economia verde: cenários para o Brasil com base no consumo de energia pela indústria

Pós-graduação em Economia - FCLAR

Microcompósitos fotocatalíticos a base de 'Ti' 'O IND.2' modificados com 'Ag'

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desenvolvimento e viabilidade econômica de mudas de espécies florestais nativas com o uso de fertirrigação em substratos a base de biossólido compostado

Pós-graduação em Ciência Florestal - FCA

Estudo ecossistêmico em uma vereda na região de Três Marias: com base em indicadores limnológicos e ecomorfológicos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)