An investigation of worn work roll materials used in the finishing stands of the hot strip mill for steel rolling

The surface failure characteristics of different work roll materials, i.e. High Speed Steel, High Chromium Iron and Indefinite Chill Iron, used in the finishing stands of a hot strip mill have been investigated using stereo microscopy, 3D optical profilometry, scanning electron microscopy and energy dispersive X-ray spectroscopy. The results show that the surface failure mechanisms of work rolls for hot rolling are very complex, involving plastic deformation, abrasive wear, adhesive wear, mechanical and thermal induced cracking, material transfer and oxidation. Despite the differences in chemical composition and microstructure, the tribological response of the different work roll materials was found to be strongly dependent on the material microstructure and especially the presence and distribution of microstructural constituents, such as the different carbide phases and graphite (in the case of Indefinite Chill Iron). Cracking and chipping of the work roll surfaces, both having a negative impact on work roll wear, are strongly influenced by the presence of carbides, carbide networks and graphite in the work roll surface. Consequently, the amount of carbide forming elements as well as the manufacturing process must be controlled in order to obtain an optimised microstructure and a predictable wear rate.

Application of X-ray technique in nondestructive evaluation of eucalypt wood

X-rays were initially used for the inspection of special-purpose wood pieces for quantitative evaluation properties of different species. X-ray densitometry has had its use expanded ill dendroclimatology of Picea engelmannii trees. Subsequent laboratories developed applications of X-ray densitometry for environmental, wood science and technology, and related areas. This paper describes the basic methodology of X-ray densitometry applied to the eucalypt wood analysis, as well its presenting the results of applications in three areas: (i) evaluation of wood biodegradation by white rot fungi, (ii) detection of sapwood and heartwood, and (iii) determination of the effect of management oil wood properties. The wood decayed by white rot fungi was detected by X-ray densitometry with it decreasing wood density due to the biodegradation of cell wall components. The sapwood and heartwood of eucalypts were separated in response to the attenuation of X-rays, reflected by the wood anatomical structure and chemical composition. Also, Ill eucalypt trees after the application of irrigation and i characteristic wood density profiles were detected. Ill addition, the significant potential of X-ray densitometry for eucalypt wood research and analysis is discussed.

Chemical and physical attributes of two substratum for eucalypt seedling production

This work evaluated the viability of one commercial substrate with pinus bark, vermiculite and 30% of coconut fiber for Eucalyptus grandis seedlings production under different water management: 6, 8, 10, 12 e 14 mm day(-1). In relation to the substrates, it was evaluated, before and after the seedlings production, the total content of carbon, nitrogen and organic substances, pH and EC of the extract, the content of macronutrients (P, K, Ca, S, Mg) and macronutrients (B, Fe, Mn, Cu, Zn), as well as total porosity, density and water retention. It was evaluated the macro and mcronutrients accumulation in the roots and in the aerial part of the seedlings, 105 days after sowing. It was concluded that the substrates presented some distinct properties of those cited as ideal for production in containers with irrigation and fertilization. At the end of the production process, both substrates registered nutrient content little influenced by water management what would guarantee the initial development of the plants in the field.

Boron transport in Eucalyptus. 2. Identification in silico of a putative boron transporter for xylem loading in eucalypt

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

Effects of bamboo stands on seed rain and seed limitation in a rainforest

Bamboos often negatively affect tree recruitment, survival, and growth, leading to arrested tree regeneration in forested habitats. Studies so far have focused on the effects of bamboos on the performance of seedlings and saplings, but the influence of bamboos on forest dynamics may start very early in the forest regeneration process by altering seed rain patterns. We tested the prediction that the density and composition of the seed rain are altered and seed limitation is higher in stands of Guadua tagoara (B or bamboo stands), a large-sized woody bamboo native from the Brazilian Atlantic Forest, compared to forest patches without bamboos (NB or non-bamboo stands). Forty 1 m(2) seed traps were set in B and NB stands, and the seed rain was monitored monthly for 1 year. The seed rain was not greatly altered by the presence of bamboos: rarefied seed species richness was higher for B stands, patterns of dominance and density of seeds were similar between stands, and differences in overall composition were slight. Seed limitation, however, was greater at B stands, likely as a resulted of reduced tree density. Despite Such reduced density, the presence of trees growing amidst and over the bamboos seems to play a key role in keeping the seeds falling in B stands because they serve as food sources for frugivores or simply as perches for them. The loss of such trees may lead to enhanced seed limitation, contributing ultimately to the self-perpetuating bamboo disturbance cycle. (C) 2008 Elsevier B,V. All rights reserved.

Fish assemblages in stream stretches occupied by cattail (Typhaceae, Angiospermae) stands in Southeast Brazil

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

Jaguarundi (Puma yagouaroundi) (Geoffroy, 1803) (Carnivora, Felidae) food habits in a mosaic of Atlantic Rainforest and eucalypt plantations of southeastern Brazil

A dieta de uma população de jaguarundi (Puma yagouaroundi) (Geoffroy, 1803) (Carnivora, Felidae) foi estudada entre novembro de 2000 e novembro de 2001, em 24,9 km² de mosaico de Mata Atlântica secundária e reflorestamento de eucalipto na Serra de Paranapiacaba, São Paulo, Brasil. A análise das 26 amostras fecais e regurgitadas, obtidas em 570.1 km de percurso, indicou o consumo de 19 itens alimentares em um total de 74 ocorrências de presas. Pequenos mamíferos foram os itens mais frequentemente encontrados na dieta (42,5%), seguidos por aves (21%), répteis (14%) e mamíferos de tamanho médio (3%). A porcentagem de ocorrência (PO) sugere que a dieta concentra-se, principalmente, em pequenos roedores (30%) e aves (21%). Foi também registrada a predação sobre serpentes da família Viperidae. A amplitude de nicho alimentar padronizada (Bsta = 0,76) mostra uma dieta generalista, entretanto, os dados sugerem que o jaguarundi consome principalmente pequenos vertebrados (mamíferos, aves ou répteis), sobretudo, espécies terrestres.

Determinação de fósforo microbiano: comparação entre métodos e coberturas florestais

Muitos trabalhos mostram a importância da biomassa microbiana do solo (BMS), principalmente como fonte/dreno de C e de N em plantações florestais; contudo, são escassos os trabalhos relacionados ao fósforo microbiano (PBM), sobretudo aqueles relativos aos métodos de determinação do PBM nesses ecossistemas. O presente trabalho foi realizado com o objetivo de avaliar métodos de determinação do PBM em solo com diferentes coberturas vegetais. O trabalho consistiu da análise de amostras de Latossolo Vermelho-Amarelo distrófico muito argiloso (LVAd) localizado no município de Viçosa (MG), coletadas nas profundidades de 0 a 5 e 5 a 10 cm, em áreas com as seguintes coberturas vegetais: pínus (Pinus taeda), eucalipto (Eucalyptus grandis) e floresta nativa. Para determinação do P microbiano, foram empregados os métodos fumigação-extração (FE), irradiação com micro-ondas-extração (IE) e irradiação com micro-ondas-extração com membrana de troca aniônica (EMTA). em termos gerais, menores teores de PBM foram obtidos com o método irradiação-extração. Considerando a cobertura vegetal, foi detectada diferença significativa entre os três métodos sob floresta de eucalipto e floresta nativa, principalmente na camada superficial. Sob pínus, apenas o método IE diferiu dos demais, na camada subsuperficial. Menores coeficientes de variação (CV) foram obtidos com o FE, retratando maior precisão do método. Entretanto, o método IE mostrou-se, em termos operacionais, o mais adequado à determinação do PBM quando se tem maior número de amostras. Com relação às coberturas vegetais, a grande variabilidade observada nos CVs obtidos para cada cobertura, nos três métodos testados, inviabiliza a escolha de um único método que apresente maior precisão na avaliação do PBM.

Nutrients cycling aspects in stands of Pinus-elliottii engelm var elliottii under differents resining intensities .1. litter fall

Litter production was measured for two years (november 1986 to october 1988) in a 29 year -old Pinus elliottii var. elliottii stand in differents resin treatments. Needle production comprised 9 to 93% of total litter fall, while the other categories (branches, barks, seeds and cones) were not significant. Maximum litterfall occurred in march to may 1987 (autumn) and the minimum was in august 1988 (winter) for all treatments and the control. No relationship appeared between annual litterfall and environmental factors, although there was a tendence to exhibit two periods of production: one in summer and other in winter. The results showed that in two years of resin extraction was not sufficient in interfering the litter fall and consequently the productivity.

Nutrient cycling aspects in stands of Pinus-elliottii engelm var elliottii under differents resining intensities .2. nutrients contents in litter

Annual and monthly quantities of nutrients wich returned to the soil through litter fall in Pinus elliottii Engelm. var. elliottii stand were estimated durint a two years period, in Experimental Station of Mogi-Guacu, SP. From the trees of the stand was extracted oleoresin according two differents techniques and control. The annual average of nutrients that returned to the soil was 72.2 Kg/ha, in following order: N > Ca > K > Mg > P. No relationship appeared between nutrient concentrations plus quantities when they were compared with oleoresin yields treatments and control. The differences in annual quantities were possibly due to climatic factors. The soil profile showed short concentrations in nutrient contents. Thus, the forest may be suffering by nutrient deficiences.

Biomass yield and calorific value of six clonal stands of Eucalyptus urophylla S. T. Blake cultivated in Northeastern Brazil

A demanda mundial por energia limpa e sustentável tem aumentado nos últimos anos. Uma das alternativas é a biomassa, incluindo os plantios florestais, com destaque, no Brasil, para o gênero Eucalyptus spp., que, atualmente, possui diversos clones selecionados para a produção de energia. Em razão da diferença na adaptação dos clones aos diferentes ambientes, há necessidade de estudos específicos para avaliar a produção de energia para determinada região. Objetivou-se, neste estudo, determinar dentre seis clones de Eucalyptus urophylla S. T. Blake analisados, aqueles com maior potencial para a produção de biomassa e energia para a região Centro Sul do Maranhão (Grajaú). Os clones foram avaliados com 41 meses de idade, plantados em espaçamento de 4 x 3 m, e distribuídos em delineamento inteiramente casualizado, com cinco repetições. Cada parcela experimental era composta por 100 árvores. Foram determinadas a produção e a alocação de biomassa de cada parte da árvore e o poder calorífico de casca e do lenho. Dos seis clones estudados, dois se destacaram tanto na produção de biomassa, quanto para a geração de energia, sendo superiores em até 27 % em comparação com o clone de menor rendimento.

Plant growth and leaf-spot severity on eucalypt at different CO2 concentrations in the air

O objetivo deste trabalho foi avaliar os efeitos do aumento da concentração de CO2 do ar sobre o crescimento de plantas e sobre a mancha foliar causada por Cylindrocladium candelabrum em Eucalyptus urophylla. As mudas foram cultivadas durante 30 dias, a 451, 645, 904, 1.147 µmol mol-1 de CO2 ; em seguida, elas foram inoculadas com o patógeno e mantidas nas mesmas condições por sete dias. O aumento da concentração de CO2 aumentou a altura de plantas e a massa de matéria seca da parte aérea, e diminuiu a incidência e a severidade da doença. O diâmetro do caule não foi afetado pelos tratamentos. O aumento das concentrações de CO2 atmosférico afeta favoravelmente o crescimento de plântulas de eucalipto e reduz a severidade da mancha foliar.

Estimating cyclopoid copepod species richness and geographical distribution (Crustacea) across a large hydrographical basin: comparing between samples from water column (plankton) and macrophyte stands

Species richness and geographical distribution of Cyclopoida freshwater copepods were analyzed along the La Plata River basin. Ninety-six samples were taken from 24 sampling sites, twelve sites for zooplankton in open waters and twelve sites for zooplankton within macrophyte stands, including reservoirs and lotic stretches. There were, on average, three species per sample in the plankton compared to five per sample in macrophytes. Six species were exclusive to the plankton, 10 to macrophyte stands, and 17 were common to both. Only one species was found in similar proportions in plankton and macrophytes, while five species were widely found in plankton, and thirteen in macrophytes. The distinction between species from open water zooplankton and macrophytes was supported by nonmetric multidimensional analysis. There was no distinct pattern of endemicity within the basin, and double sampling contributes to this result. This lack of sub-regional faunal differentiation is in accordance with other studies that have shown that cyclopoids generally have wide geographical distribution in the Neotropics and that some species there are cosmopolitan. This contrasts with other freshwater copepods such as Calanoida and some Harpacticoida. We conclude that sampling plankton and macrophytes together provided a more accurate estimate of the richness and geographical distribution of these organisms than sampling in either one of those zones alone.

Heating value of eucalypt wood grown on SRC for energy production

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)