977 resultados para Soil physical and chemical characters


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El foc bacterià és una malaltia que afecta a plantes de la família de la rosàcies, causada pel bacteri Erwinia amylovora. El seu rang d'hostes inclou arbres fruiters, com la perera, la pomera o el codonyer, i plantes ornamentals de gran interès comercial i econòmic. Actualment, la malaltia s'ha dispersat i es troba àmpliament distribuïda en totes les zones de clima temperat del món. A Espanya, on la malaltia no és endèmica, el foc bacterià es va detectar per primer cop al 1995 al nord del país (Euskadi) i posteriorment, han aparegut varis focus en altres localitzacions, que han estat convenientment eradicats. El control del foc bacterià, és molt poc efectiu en plantes afectades per la malaltia, de manera que es basa en mesures encaminades a evitar la dispersió del patogen, i la introducció de la malaltia en regions no endèmiques. En aquest treball, la termoteràpia ha estat avaluada com a mètode d'eradicació d'E. amylovora de material vegetal de propagació asimptomàtic. S'ha demostrat que la termoteràpia és un mètode viable d'eradicar E. amylovora de material de propagació. Gairebé totes les espècies i varietats de rosàcies mantingudes en condicions d'humitat sobrevivien 7 hores a 45 ºC i més de 3 hores a 50 ºC, mentre que més d'1 hora d'exposició a 50 ºC amb calor seca produïa danys en el material vegetal i reduïa la brotació. Tractaments de 60 min a 45 ºC o 30 min a 50 ºC van ser suficients per reduir la població epífita d'E. amylovora a nivells no detectables (5 x 102 ufc g-1 p.f.) en branques de perera. Els derivats dels fosfonats i el benzotiadiazol són efectius en el control del foc bacterià en perera i pomera, tant en condicions de laboratori, com d'hivernacle i camp. Els inductors de defensa de les plantes redueixen els nivells de malaltia fins al 40-60%. Els intervals de temps mínims per aconseguir el millor control de la malaltia van ser 5 dies pel fosetil-Al, i 7 dies per l'etefon i el benzotiadiazol, i les dosis òptimes pel fosetil-Al i el benzotiadiazol van ser 3.72 g HPO32- L-1 i 150 mg i.a. L-1, respectivament. Es millora l'eficàcia del fosetil-Al i del benzotiadiazol en el control del foc bacterià, quan es combinen amb els antibiòtics a la meitat de la dosi d'aquests últims. Tot i que l'estratègia de barrejar productes és més pràctica i fàcil de dur a terme a camp, que l'estratègia de combinar productes, el millor nivell de control de la malaltia s'aconsegueix amb l'estratègia de combinar productes. Es va analitzar a nivell histològic i ultrastructural l'efecte del benzotiadiazol i dels fosfonats en la interacció Erwinia amylovora-perera. Ni el benzotiadiazol, ni el fosetil-Al, ni l'etefon van induir canvis estructurals en els teixits de perera 7 dies després de la seva aplicació. No obstant, després de la inoculació d'E. amylovora es va observar en plantes tractades amb fosetil-Al i etefon una desorganització estructural cel·lular, mentre que en les plantes tractades amb benzotiadiazol aquestes alteracions tissulars van ser retardades. S'han avaluat dos models (Maryblyt, Cougarblight) en un camp a Espanya afectat per la malaltia, per determinar la precisió de les prediccions. Es van utilitzar dos models per elaborar el mapa de risc, el BRS-Powell combinat i el BIS95 modificat. Els resultats van mostrar dos zones amb elevat i baix risc de la malaltia. Maryblyt i Cougarblight són dos models de fàcil ús, tot i que la seva implementació en programes de maneig de la malaltia requereix que siguin avaluats i validats per un període de temps més llarg i en àrees on la malaltia hi estigui present.

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Micromorphological characters of the fruiting bodies, such as ascus-type and hymenial amyloidity, and secondary chemistry have been widely employed as key characters in Ascomycota classification. However, the evolution of these characters has yet not been studied using molecular phylogenies. We have used a combined Bayesian and maximum likelihood based approach to trace character evolution on a tree inferred from a combined analysis of nuclear and mitochondrial ribosomal DNA sequences. The maximum likelihood aspect overcomes simplifications inherent in maximum parsimony methods, whereas the Markov chain Monte Carlo aspect renders results independent of any particular phylogenetic tree. The results indicate that the evolution of the two chemical characters is quite different, being stable once developed for the medullary lecanoric acid, whereas the cortical chlorinated xanthones appear to have been lost several times. The current ascus-types and the amyloidity of the hymenial gel in Pertusariaceae appear to have been developed within the family. The basal ascus-type of pertusarialean fungi remains unknown. (c) 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 89, 615-626.

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The objective of this study was to evaluate the effects of diet supplementation with vitamin E on the physical and chemical characteristics of ground, frozen and stored or aged Quadriceps femoris (QF) and Longissimus dorsi (LD) muscles from Nellore steers fed high concentrate diets. Muscles were obtained from 24 animals that were 30 months old with a mean live weight of 279 kg. Half of the animals received daily doses of 1,000 mg of alpha-tocopherol acetate (VIT E) per head per day that was added to 100 g of corn meal. The other half received 100 g of corn meal without the antioxidant. Twenty-four hours after slaughtering, QF samples from each animal were ground, frozen and stored for up to 6 months. In addition, 4 samples from the LD of each animal were vacuum packed individually and kept for 21 days. All samples were analyzed to determine the pH, color and water-holding-capacity. The VIT E supplementation improved only the water loss characteristics of frozen ground QF and did not have any positive effect on the physical-chemical characteristics of the aged LD.

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

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O trabalho teve como objetivo a caracterização físico-química de frutos de mangostão amarelo (Garcinia xanthochymus Hook). Seis amostras de 25 frutos cada foram colhidas em plantas de mangostão amarelo do Banco Ativo de Germoplasma da Universidade Estadual Paulista e caracterizadas pela avaliação de diâmetro e altura, peso, percentagem e número de sementes por fruto, percentagem de casca, percentagem de polpa, sólidos solúveis (SS), acidez titulável (AT), vitamina C e relação SS/AT. O mangostão amarelo tem boas qualidades tecnológicas e é uma fonte intermediária de vitamina C com conteúdo médio de 120,33 mg/100g de fruta fresca.

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

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

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

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Objective. The aim of this study was to evaluate the pH, calcium release, setting time, and solubility of two commercially available mineral trioxide aggregate (MTA) cements (white MTA Angelus and MTA Bio), and of three experimental cements (light-cured MTA, Portland cement with 20% bismuth oxide and 5% calcium sulfate, and an epoxy resin-based cement).Study design. For evaluation of pH and calcium ion release, polyethylene tubes with 1.0 mm internal diameter and 10.0 mm length were filled with the cements and immediately immersed in flasks containing 10 mL deionized water. After 3, 24, 72, and 168 hours, the tubes were removed and the water from the previous container was measured for its pH and calcium content with a pH meter and an atomic absorption spectrophotometer. For analysis of the setting time, Gilmore needles weighing 100 g and 456.5 g were used, in accordance with the American Society for Testing and Materials specification no. C266-03. Solubility of each cement was also tested.Results. All the cements were alkaline and released calcium ions, with a declining trend over time. After 3 hours, Portland cement + bismuth oxide and MTA Bio had the highest pH and light-cured MTA the lowest. After 1 week, MTA Bio had the highest pH and light-cured MTA and epoxy resin-based cement the lowest. Regarding calcium ion release, after 3 hours, Portland cement + bismuth oxide showed the highest release. After 1 week, MTA Bio had the highest. Epoxy resin-based cement and light-cured MTA had the lowest calcium release in all evaluation periods. Regarding setting times, white MTA Angelus and MTA Bio had the shortest, Portland cement + bismuth oxide had an intermediate setting time, and the epoxy resin-based cement had the longest. The materials that showed the lowest solubility values were the epoxy resin-based cement, Portland cement + bismuth oxide, and light-cured MTA. The highest solubility values were presented in white MTA Angelus and MTA Bio.Conclusions. The white MTA Angelus and MTA Bio had the shortest setting times, higher pH and calcium ion release, and the highest solubility. In contrast, the epoxy resin-based cement and light-cured MTA showed lower values of solubility, pH, and calcium ion release. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010; 110: 250-256)

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Duarte MAH, Alves de Aguiar K, Zeferino MA, Vivan RR, Ordinola-Zapata R, Tanomaru-Filho M, Weckwerth PH, Kuga MC. Evaluation of the propylene glycol association on some physical and chemical properties of mineral trioxide aggregate. International Endodontic Journal, 45, 565570, 2012. Abstract Aim To evaluate the influence of propylene glycol (PG) on the flowability, setting time, pH and calcium ion release of mineral trioxide aggregate (MTA). Methodology Mineral trioxide aggregate was mixed with different proportions of PG, as follows: group 1: MTA + 100% distilled water (DW); group 2: MTA + 80% DW and 20% PG; group 3: MTA + 50% DW and 50% PG; group 4: MTA + 20% DW and 80% PG; group 5: MTA + 100% PG. The ANSI/ADA No. 57 was followed for evaluating the flowability and the setting time was measured by using ASTM C266-08. For pH and calcium release analyses, 50 acrylic teeth with root-end cavities were filled with the materials (n = 10) and individually immersed in flasks containing 10 mL deionized water. After 3 h, 24 h, 72 h and 168 h, teeth were placed in new flasks and the water in which each specimen was immersed had its pH determined by a pH metre and the calcium release measured by an atomic absorption spectrophotometer with a calcium-specific hollow cathode lamp. Data were analysed by using one-way anova test for global comparison and by using Tukeys test for individual comparisons. Results The highest value of flowability was observed with MTA + 20% DW and 80% PG and the lowest values were found with MTA + 100% DW. They were significantly different compared to the other groups (P < 0.05). The presence of PG did not affect the pH and calcium release. The MTA + 100% PG favoured the highest (P < 0.05) pH and calcium release after 3 h. Increasing the PG proportion interfered (P < 0.05) with the setting time; when used at the volume of 100% setting did not occur. Conclusion The addition of PG to MTA-Angelus increased its setting time, improved flowability and increased the pH and calcium ion release during the initial post-mixing periods. The ratio of 80% DW 20% PG is recommended.

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Physical and chemical characteristics of sediment were analyzed at eight sampling areas in the estuarine region of Cananeia (SP), Brazil. The samples were collected in 1995 during four periods; summer, autumn, winter and spring. Total nitrogen and phosphorus concentrations, redox potential, water and organic matter percentage, sand and silt percentage and grain size were determined in six different layers of 20 cm deep columns of sediment. In general, the nutrient concentration and the percentage of organic matter decreased with depth and greater variations were observed in the first centimeter of the samples. Differences in nutrient concentration and organic matter were also observed during the study period. The highest concentrations were recorded during the rainy season (February) as a consequence of an accumulation of organic matter brought into the system by rivers and adjacent flooded areas. In general, the sediments had oxidized characteristics until the 5 or 10 cm depth in areas near the rich coastal vegetation. However, in areas open to the ocean, the entire sediment columns were almost completely oxidized.

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The aim of this paper is to investigate the influence of physical and chemical factors on transport and use of substrate for Atta sexdens rubropilosa workers. Three types of rectangular fragments were used to study the physical influence factors: filter paper with paraffin, filter paper without paraffin and polyester film. To study the chemical factors, some fragments were impregnated with organic extract of orange albedo, others were soaked with soybean oil and for the remaining ones nothing was applied. The following parameters were evaluated: (i) attractiveness of substrate for transport and number of loading workers per treatment; (ii) foraged material incorporation; (iii) rejection by numbers of fragments deposited in the garbage or beside the fungus garden. All the polyester film fragments carried out to the fungus garden were subsequently rejected. We verified that chemical factors of the substrate were more quickly detected by the workers, whereas physical factors were used as a criterion in the decision-making to reject or accept the substrate collected.

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

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Devido às mudanças climáticas do planeta, principalmente ao aquecimento global, as formas de utilização dos solos na agricultura têm atraído grande atenção de pesquisadores. Mudanças de manejo podem influenciar a respiração do solo e, por conseguinte, alterar drasticamente o sequestro de C. Os objetivos deste trabalho foram avaliar, em semeadura direta, a influência da calagem nas emissões de CO2 do solo e correlacioná-las aos atributos químicos deste após dois anos da calagem. Utilizou-se o delineamento em blocos casualizados, com seis repetições. Os tratamentos constituíram de quatro doses de calcário e uma testemunha. Decorridos dois anos da calagem, avaliou-se a emissão residual de CO2 do solo, coletaram-se amostras nas camadas de 0-5, 5-10, 10-20 e 20-30 cm de profundidade e determinaram-se os teores de P, Ca2+ e Mg2+ e valores de pH e de saturação por bases. A emissão residual de CO2 do solo, quando a dose recomendada foi aplicada, foi 24,1 % superior, quando comparada à do solo sem aplicação de calcário, e 47,4 % maior, quando se aplicou o dobro da dose recomendada. A calagem melhorou as condições químicas do solo, e a emissão de CO2 aumentou linearmente com o aumento das doses. A emissão de CO2 do solo apresentou correlações positivas com os teores de P, Ca2+ e Mg2+ e com os valores de pH e de saturação por bases e negativas com os teores de H + Al e Al3+. Maiores coeficientes de correlação entre as taxas de emissão de CO2 do solo e os atributos químicos deste ocorreram na camada de 10-20 cm.