46 resultados para wood-to-wood bonding
Resumo:
O gênero Lepidagathis apresenta distribuição pantropical com cerca de 100 espécies. No Brasil ocorrem 16 espécies, a maioria nas regiões Centro - Oeste e Sudeste. O estudo foi realizado em sub - bosque de remanescente florestal do município de Tangará da Serra - MT e teve como objetivo analisar a fenologia de floração, descrever a morfologia e biologia floral, verificar os visitantes florais e avaliar o sistema e o sucesso reprodutivo por meio de polinizações manuais. Lepidagathis sessilifolia apresenta inflorescências espiciformes, terminais, com cálice de cor rósea vistosa e corola de coloração branco-rósea. A floração ficou restrita aos meses de março a abril, durante a estação chuvosa. A senescência floral ocorreu após 24 ou 48 horas. A viabilidade dos grãos de pólen foi elevada (92,5%). O único polinizador observado visitando as flores de L. sessilifolia foi a abelha Partamona nhambiquara (Apidae - Meliponini). O sistema reprodutivo misto da espécie é caracterizado pela formação de frutos por meio de agamospermia, autopolinização e polinização cruzada. Esse sistema reprodutivo flexível é vantajoso, pois, garante a manutenção da espécie na área de estudo mesmo na ausência de polinizadores.
Resumo:
Allergen-induced bone marrow responses are observable in human allergic asthmatics, involving specific increases in eosinophil-basophil progenitors (Eo/B-CFU), measured either by hemopoietic assays or by flow cytometric analyses of CD34-positive, IL-3Ralpha-positive, and/or IL-5-responsive cell populations. The results are consistent with the upregulation of an IL-5-sensitive population of progenitors in allergen-induced late phase asthmatic responses. Studies in vitro on the phenotype of developing eosinophils and basophils suggest that the early acquisition of IL-5Ralpha, as well as the capacity to produce cytokines such as GM-CSF and IL-5, are features of the differentiation process. These observations are consistent with findings in animal models, indicating that allergen-induced increases in bone marrow progenitor formation depend on hemopoietic factor(s) released post-allergen. The possibility that there is constitutive marrow upregulation of eosinophilopoiesis in allergic airways disease is also an area for future investigation.
Resumo:
Artificial ecotopes of 121 peridomiciliary environments in four rural localities in the state of Ceará, Brazil, were studied and the type of material of the ecotopes was identified as triatomine infestation. Two thousand two hundred and four Triatoma brasiliensis Neiva, 340 Triatoma pseudomaculata Corrêa and Espínola, 121 Rhodnius nasutus Stall, and 5 Panstrongylus lutzi (Neiva and Pinto) were captured. Out of the 323 ecotopes found (X =2.0 ± 1.8 per dwelling) such as pigpens, henhouses, corrals, perches, dovecotes, piles of roofing tiles, bricks, wood, and straw 30.3% were infested by triatomines in all different developmental stages, including eggs. A substantial number of triatomines were found in perches, however the largest infestation took place in roofing materials used in the construction of goat/sheep corrals, henhouses, and pigpens, where 98% of them were captured: 1372 triatomines were located in the roofing tile covers, 285 in the straw, 187 in the perches, 77 in the coverings of roofing tiles and straw, and 13 in the straw and wood. Among all the different pile of materials, roofing tiles were the most infested (50%) followed by bricks (38.9%) and woods (36.1%). T. brasiliensis colonized mainly brick piles (chi2=16.539; p < 0.05) and roofing tiles (chi2=5,090.58; p < 0.05); T. pseudomaculata preferred wood perches (chi2= 472.39; p < 0.05) and woodpiles (chi2=126.0 p < 0.05), and R. nasutus was principally found in roofing straw (chi2=384.43; p < 0.05). These findings suggest that triatomines tend to colonize peridomiciliary ecotopes similar to their original habitats.
Resumo:
Infusions of Aspidosperma nitidum (Apocynaceae) wood bark are used to treat fever and malaria in the Amazon Region. Several species of this family are known to possess indole alkaloids and other classes of secondary metabolites, whereas terpenoids, an inositol and the indole alkaloids harmane-3 acid and braznitidumine have been described in A. nitidum . In the present study, extracts from the wood bark, leaves and branches of this species were prepared for assays against malaria parasites and cytotoxicity testing using human hepatoma and normal monkey kidney cells. The wood bark extracts were active against Plasmodium falciparum and showed a low cytotoxicity in vitro, whereas the leaf and branch extracts and the pure alkaloid braznitidumine were inactive. A crude methanol extract was subjected to acid-base fractionation aimed at obtaining alkaloid-rich fractions, which were active at low concentrations against P. falciparum and in mice infected with and sensitive Plasmodium berghei parasites. Our data validate the antimalarial usefulness of A. nitidum wood bark, a remedy that can most likely help to control malaria. However, the molecules responsible for this antimalarial activity have not yet been identified. Considering their high selectivity index, the alkaloid-rich fractions from the plant bark might be useful in the development of new antimalarials.
Resumo:
During timber exploitation in forest stands harvesting machines pass repeatedly along the same track and can cause soil compaction, which leads to soil erosion and restricted tree root growth. The level of soil compaction depends on the number of passes and weight of the wood load. This paper aimed to evaluate soil compaction and eucalyptus growth as affected by the number of passes and wood load of a forwarder. The study was carried out in Santa Maria de Itabira county, Minas Gerais State - Brazil, on a seven-year-old eucalyptus stand planted on an Oxisol. The trees were felled by chainsaw and manually removed. Plots of 144 m² (four rows 12 m long in a 3 x 2 m spacing) were then marked off for the conduction of two trials. The first tested the traffic intensity of a forwarder which weighed 11,900 kg and carried 12 m³ wood (density of 480 kg m-3) and passed 2, 4, and 8 times along the same track. In the second trial, the forwarder carried loads of 4, 8, and 12 m³ of wood, and the machine was driven four times along the same track. In each plot, the passes affected four rows. Eucalyptus was planted in 30 x 30 x 30 cm holes on the compacted tracks. The soil in the area is clayey (470 clay and 440 g kg-1 sand content) and at depths of 0-5 cm and 5-10 cm, respectively, soil organic carbon was 406 and 272 g kg-1 and the moisture content during the trial 248 and 249 g kg-1. These layers were assessed for soil bulk density and water-stable aggregates. The infiltration rate was measured by a cylinder infiltrometer. After 441 days the measurements were repeated, with additional analyses of: soil organic carbon, total nitrogen, N-NH4+, N-NO3-, porosity, and penetration resistance. Tree height, stem diameter, and stem dry matter were measured. Forwarder traffic increased soil compaction, resistance to penetration and microporosity while it reduced the geometric mean diameter, total porosity, macroporosity and infiltration rate. Stem dry matter yield and tree height were not affected by soil compaction. Two passes of the forwarder were enough to cause the disturbances at the highest levels. The compaction effects were still persistent 441 days after forwarder traffic.
Resumo:
The aim of these studies was to investigate whether residual toxic effects of exposing soybean root nodule bacteria to Al in a solid defined media (SDM) alter tolerance to Al, survival, sensitivity to antibiotics, N2 fixation effectiveness and genetic diversity of Bradyrhizobium strains. After being exposed four times to Al, strains showed variation in Al tolerance but there was no evidence of change in their original Al tolerance, sensitivity to the antibiotics or genetic diversity. Exposure of Bradyrhizobium strains to SDM plus Al did not alter biological N2 fixation effectiveness of five strains. Strain SEMIA 587 showed a reduction in its N2 fixation effectiveness but it seems that it was just a superficial toxic effect because one single passage through the plant eliminated this effect. Residual Al did not cause increases in Al tolerance and reductions in the survival and N2 fixation effectiveness of Bradyrhizobium strains USDA 143, SEMIA 586, SEMIA 5019, SEMIA 5039 and SEMIA 5073. It also did not alter the resistance to antibiotics of strains USDA 143, SEMIA 5039 and SEMIA 5073, and the genetic diversity of the strains SEMIA 587 and SEMIA 5019.
Resumo:
This study has shown that Eucalyptus tar and creosote can be used in phenolic adhesive formulations (resols) for wood products bonding. Some adhesives were prepared substituting 0; 17.7; 35.0 and 67.0% of the phenol by anhydrous tar and 0; 15.0 e 28.5% by creosote. In gluing Brazilian pine veneers, eucalypt tar and creosote based adhesives required longer pressing times for curing than conventional phenol-formaldehyde adhesives. By using 13C NMR, the number of carbons in side chains and hydroxyl, carbonyl, carboxyl and methoxyl groups related to 100 aromatic rings could be estimated in tar and creosote. In creosote, after reaction with excess formaldehyde in alkaline medium, only 0,28 hydroxymethyl groups was detected per phenolic ring. This low amount of hydroxymethylation explains the lack of reactivity in curing observed when creosote was introduced in a standard adhesive formulation.
Resumo:
The phytochemical investigation of the wood extracts of Senna reticulata (Leguminoseae) yielded six anthraquinones: chrysophanol, physcion, aloe-emodin, 1,3,8-trihydroxyanthraquinone, 3-methoxy-1,6,8-trihydroxyanthraquinone, emodin and the chrysophanol-10,10' bianthrone. The triterpenes a and b-amirin, the steroids b-sitosterol and stigmasterol as well as the flavonoid kaempferol were also identified. The structures were established by spectral analysis, including two-dimensional NMR techniques. It is the first report of 1,3,8-trihydroxyanthraquinone and 3-methoxy-1,6,8-trihydroxyanthraquinone in higher plants.
Resumo:
Phytochemical investigation of the wood from Zanthoxylum quinduense Tul. allowed the isolation and identification of norchelerythrine, decarine, 6-acetonyldihydrochelerythrine, syringaresinol, evofilin C, p-hydroxybenzaldehyde, vanillic acid, a mixture of β-sitosterol, stigmasterol and campesterol and a mixture of saturated and unsaturated fatty acids, and their esters derivatives. The structures of the isolated compounds were elucidated by spectroscopic techniques and comparison with literature data and the mixture of sterols and fatty acids were identified by GC/MS. The antifungal activity of the ethanolic extract, fractions and pure compounds against Fusarium oxysporum f. sp. lycopersici was determined by bioautography. Evofilin C and nochelerytrine were the only substances that present antifungal activity.
Resumo:
Acacia mearnsii de Wild (black wattle) is one of the most important trees planted in Southern Brazil for tannin extraction and charcoal production. The pyrolysis of the black wattle wood used for obtaining charcoal is performed in brick ovens, with the gas fraction being sent directly into the environment. The present study examines the condensable compounds present in the liquor produced from black wattle wood at different thermal degradation conditions, using gas chromatography coupled with mass spectrometry (GC/MS). Branches of black wattle were thermally degraded at controlled ambient and temperature conditions. Overall, a higher variety of compounds were obtained under atmospheric air pressure than under synthetic air pressure. Most of the tentatively identified compounds, such as carboxylic acids, phenols, aldehydes, and low molecular mass lignin fragments, such as guayacol, syringol, and eugenol, were products of lignin thermoconversion. Substituted aromatic compounds, such as vanillin, ethyl vanillin, and 2-methoxy-4-propeny-phenol, were also identified. At temperatures above 200 ºC, furan, 2-acetylfuran, methyl-2-furoate, and furfural, amongst others, were identified as polysaccharide derivatives from cellulose and hemicellulose depolymerization. This study evidences the need for adequate management of the condensable by-products of charcoal production, both for economic reasons and for controlling their potential environmental impact.
Resumo:
Trees with stem bark lesions are frequently observed in Eucalyptus globulus Labill. plantations, particularly in the central west region of Uruguay. These lesions constitute a problem for trunk decortications at harvest and they also facilitate the access of fungi that could cause wood decay. Seven, three and oneyear-old plantations, located at three sites in close proximity were selected. Four types of trunk lesions were present in trees regardless the age of plantation and more than one type was found in each plantation. The aim of this study was to investigate the fungal composition associated with these lesions and compare them to healthy tissues and try to find out the origin of these symptoms. Another purpose was to elucidate the real role of the fungi considered pathogens by means of experimental inoculations. Segments from lesions and healthy tissues yielded 897 fungal isolates belonging to 32 taxa, 681 isolates from bark lesions and 216 from healthy tissues. Both healthy and symptomatic tissues showed similar fungal species composition, but with differences in frequencies of colonization. Cytospora eucalypticola Van der Westhuizen, Botryosphaeria spp., Pestalotiopsis guepinii (Desm.) Stey. and Penicillium spp. were the dominant species isolated. As symptoms were not reproduced after experimental inoculation with Botryosphaeria ribis Grossenb. & Duggar and B. eucalyptorum Crous, & M.J. Wingf, it could be suggested that these lesions were originated by unfavorable environmental conditions. The frost that occurred for several days out of season and flooding may have been involved in the development of bark lesion.
Resumo:
Termites are well known for their ability to damage wood and various types of wood-derived products. This study was performed in the municipality of Seropédica, Rio de Janeiro state, Brazil, with the objective of evaluating the susceptibility of the wood of five different forest species to the activity of the Asian subterranean termite, Coptotermes gestroi. Wood stakes from the following forest species were used as specimens: pine (Pinus sp., Pinaceae), Brazil nut (Bertholletia excelsa, Lecythidaceae), cabbage angelin (Andira inermis, Leguminosae-Papilionoideae), maçaranduba (Manilkara huberi, Sapotaceae) and pink ipê (Tabebuia avellanedae, Bignoniaceae). The stakes, with dimensions of 2 cm x 2 cm x 16 cm, were subjected to the activity of C. gestroi from September 2, 2006 to June 2, 2007. The experimental design consisted of randomized blocks with four replications in an 11 x 5 x 3 factorial arrangement. Twelve stakes of each of the five forest species were installed at each of eleven sites, totaling 660 stakes. Three evaluations were performed, at 90, 180 and 270 days after stake installation. The results indicated that the pine, Brazil nut and cabbage angelin stakes were more susceptible to C. gestroi attack, while the pink ipê and maçaranduba stakes suffered no significant damage from this termite. There was a significant negative correlation between the wood consumption rate and the wood density of the species studied. The woods most susceptible to C. gestroi attack presented moderate to low densities and therefore less resistance, as in the case of pine and cabbage angelin.
Resumo:
ABSTRACTFour stands of 28-year-old radiata pine (Pinus radiata D. Don) grown in the eighth region (Biobio) of Chile were sampled to determine the effect of tree spacing on the microfibril angle. The samples were taken at two different stem levels of the tree, 2.5 m and 7.5 m, with increment strip taken in the Nothern direction. The four experimental stands were characterized by the following spacing 2x2, 2x3, 3x4 and 4x4. The microfibril angle was measured by X-ray diffraction with the SilviScan technology at the FP-Innovation-Paprican Division in Vancouver, Canada. The results showed a significant effect of tree spacing on the microfibril angle in both juvenile wood and mature wood as well as at the two stem levels considered. The minimum (9.42º) was reached in 2x2 stand at 7.5 m in mature wood, while maximum microfibril angle (24.54º) was obtained in 2x3 stand at 2.5 m in juvenile wood. Regarding the effect of tree spacing, 4x4 stand had the lowest microfibril angle,except in mature wood at 7.5 m where 4x4 had the highest microfibril angle (11°) of the four stands.
Resumo:
In São Paulo State, mainly in rural areas, the utilization of wooden poles is observed for different purposes. In this context, wood in contact with the ground presents faster deterioration, which is generally associated to environmental factors and, especially to the presence of fungi and insects. With the use of mathematical models, the useful life of wooden structures can be predicted by obtaining "climatic indexes" to indicate, comparatively among the areas studied, which have more or less tendency to fungi and insects attacks. In this work, by using climatological data of several cities at São Paulo State, a simplified mathematical model was obtained to measure the aggressiveness of the wood in contact with the soil.
Resumo:
The Thr(118)Met substitution in the peripheral myelin protein 22 (PMP22) gene has been detected in a number of families with demyelinating Charcot-Marie-Tooth (CMT1) neuropathy or with the hereditary neuropathy with liability to pressure palsy, but in none of them has it consistently segregated with the peripheral neuropathy. We describe here a CMT1 family (a 63-year-old man, his brother and his niece) in which two mutations on different chromosomes were found in the PMP22 gene, the 17p duplication, detected by fluorescent semiquantitative polymerase chain reaction (PCR) of microsatellite markers localized within the duplicated region on chromosome 17p11.2-p12, and the Thr(118)Met substitution, detected by direct sequencing the four coding exons of the PMP22 gene. A genotype/phenotype correlation study showed that the neuropathy segregates with the duplication and that the amino acid substitution does not seem to modify the clinical characteristics or the severity of the peripheral neuropathy. We did not find any evidence to characterize this substitution as a polymorphism in the population studied and we propose that the high frequency reported for this point mutation in the literature suggests that the Thr(118)Met substitution may be a hotspot for mutations in the PMP22 gene.