Rhizobial characterization in revegetated areas after bauxite mining

Abstract Little is known regarding how the increased diversity of nitrogen-fixing bacteria contributes to the productivity and diversity of plants in complex communities. However, some authors have shown that the presence of a diverse group of nodulating bacteria is required for different plant species to coexist. A better understanding of the plant symbiotic organism diversity role in natural ecosystems can be extremely useful to define recovery strategies of environments that were degraded by human activities. This study used ARDRA, BOX-PCR fingerprinting and sequencing of the 16S rDNA gene to assess the diversity of root nodule nitrogen-fixing bacteria in former bauxite mining areas that were replanted in 1981, 1985, 1993, 1998, 2004 and 2006 and in a native forest. Among the 12 isolates for which the 16S rDNA gene was partially sequenced, eight, three and one isolate(s) presented similarity with sequences of the genera Bradyrhizobium, Rhizobium and Mesorhizobium, respectively. The richness, Shannon and evenness indices were the highest in the area that was replanted the earliest (1981) and the lowest in the area that was replanted most recently (2006).

Comparative study between yeasts immobilized on alumina beads and on membranes prepared by two routes

Alumina channeled beads and rough surface membranes prepared from aqueous sols of fibrillar pseudoboehmite are able to immobilize yeasts for ethanol fermentation of sugar solutions. This paper describes comparative results of assays carried out with yeasts immobilized onto alpha-alumina beads and membranes prepared under two different conditions of processing and firing. The fermentation tests evaluated by the decrease of fermentable sugars, referred as Brix degrees per hour, indicated that the yeasts immobilized on beads had similar performance, probably because their surfaces, even being morphologically different, presented the same value of open porosity. One type of membrane (asymmetrical; precursor: pseudoboehmite; firing temperature 1,150liC; crystal structure; alpha-alumina) had better performance than the other type (asymmetrical; precursor: fibrillar pseudoboehmite plus aluminum hydroxiacetate mixture; 1,150liC; alpha-alumina) because the yeast cells entered into their porous interior through the surface slits, were immobilized and their growth was easier than on the external surface.

Medida da condutividade eletrica em medicamentos homeopaticos (III) / Electric condutivity measurements in homeopathic remedies (III)

Atraves da medida da condutividade eletrica dos medicamentos Alumina e Lycopodium, nas dinamizacoes C3, C6, C12, C15 e C30, os autores mostram que a maior porcentagem de agua presente no veiculo a ser utilizado na manipulacao do medicamento homeopatico, aumenta os valores de condutividade deste medicamento dinamizado, estimulando o poder energetico do mesmo

Prótese adesiva indireta: avaliaçäo da resistência de uniäo de uma liga de Ni-Cr-Be (Litecast B) usando dois tipos de agentes para fixaçäo - Conclude (com ataque eletrolítico) e Panavia Ex (sem ataque eletrolítico) - em quatro tipos de preparos / Indirect adhesive prosthesis: evaluation of the bond strength of a Ni-Cr-Be alloy (Litecast B) using two types of bonding agents - Conclude (with electrolytic etching) and Panavia Ex (without electrolytic etching) - in four preparation types

O objetivo deste trabalho foi verificar a resistência de uniäo de restauraçöes atacadas eletroliticamente e fixadas com Conclude, usando 2 agentes de uniäo no esmalte (Scotchbond e Concise) e restauraçöes tratadas apenas com jatos de óxido de alumínio e fixadas com Panavia Ex. Foram utilizados 4 tipos de preparos para próteses adesiva: desgaste lingual e proximais com 1 nicho oclusal (preparo 1); desgaste lingual e proximais com 2 nichos oclusais (preparo 2); desgaste lingual e proximais com caixas ocluso-proximal (preparo 3) e preparo para coroa total (preparo 4). Todos os preparos foram realizados em esmalte. Para isso, foram selecionados 90 molares recém-extraídos e incluídos em cilindros de resina acrília e as restauraçöes fundidas com uma liga de Ni-Cr-Be (Litecast B). Após a fixaçäo, as restauraçöes foram removidas por traçäo em uma máquina de ensaios Universal (Instron) à uma velocidade de 0,5mm/minuto. Com base nos resultados obtidos, concluiu-se: A utilizaçäo do Scotchbond como agente de uniäo em esmalte influenciou positivamente na resistência de uniäo, embora näo tenha ocorrido diferença estatisticamente significante; Comparando os 4 tipos de preparos, as restauraçöes fixadas com Conclude, no preparo n§ 4, apresentaram os melhores resultados seguidos pelos preparos n§ 2, 1 e 3; Com Panavia Ex, o preparo n§ 4 apresentou os melhores resultados seguidos pelos preparos n§ 3, 1 e 2; As restauraçöes fixadas com Panavia Ex, apresentaram resultados superiores aos fixados com Conclude, especificamente com os preparos n§ 3 e 4; Esses resultados mostram que restauraçöes fixadas com Conclude ou Panavia Ex, podem ser indicadas com retentores para próteses fixas adesivas em dentes posteriores