Elastic modulus of posts and the risk of root fracture

The definition of an optimal elastic modulus for a post is controversial. This work hypothesized that the influence of the posts` elastic modulus on dentin stress concentration is dependent on the load direction. The objective was to evaluate, using finite element analysis, the maximum principal stress (sigma(max)) on the root, using posts with different elastic modulus submitted to different loading directions. Nine 3D models were built, representing the dentin root, gutta-percha, a conical post and the cortical bone. The softwares used were: MSC.PATRAN2005r2 (preprocessing) and MSC.Marc2005r2 (processing). Load of 100 N was applied, varying the directions (0 degrees, 45 degrees and 90 degrees) in relation to the post`s long axis. The magnitude and direction of the sigma(max) were recorded. At the 45 degrees and 90 degrees loading, the highest values of sigma(max) were recorded for the lowest modulus posts, on the cervical region, with a direction that suggests debonding of the post. For the 0 degrees loading, the highest values of sigma(max) were recorded for higher modulus posts, on the apical region, and the circumferential direction suggests vertical root fracture. The hypothesis was accepted: the effect of the elastic modulus on the magnitude and direction of the sigma(max) generated on the root was dependent on the loading direction.

A longitudinal study of quality of life of elderly with mandibular implant-supported fixed prostheses

Objectives: To verify the consequences of implant-supported fixed oral rehabilitation on the quality of life (QL) of elderly individuals. Material and methods: Fifteen patients were studied, being 10 females and five males; all were aged > 60 years, were completely edentulous, wore removable dentures on both arches, and were treated with implant-supported fixed dentures. Three QL questionnaires were applied, two related to the oral conditions (Oral Impact on Daily Performance - OIDP - and Oral Health Impact Profile, short version - OHIP-14) and one dealing with global aspects (World Health Organization Quality of Life - WHOQOL-BREF), before 3, 6, and 18 months after surgical placement of implants. Results: Scores in the OIDP and OHIP-14 questionnaires were better after dental treatment. The WHOQOL-BREF was less sensitive, confirming the higher reliability of specific questionnaires (focal) compared with general questions in such situations. Conclusion: Treatment with implant-supported fixed prostheses improved QL in the elderly; these effects are better detected by specific instruments focused on the subject.

Longitudinal Study of Growth of Children With Unilateral Cleft-Lip Palate From Birth to Two Years of Age

Objective: To study the growth of children with complete unilateral cleft lip and palate (UCLP) from birth to 2 years of age and to construct specific UCLP growth curves. Design: Physical growth was a secondary outcome measure of a National Institutes of Health-sponsored longitudinal, prospective clinical trial involving the University of Florida (United States) and the University of Sao Paulo (Brazil). Patients: Six hundred twenty-seven children with UCLP, nonsyndromic, both genders. Methods: Length, weight, and head circumference were prospectively measured for a group of children enrolled in a clinical trial. Median growth curves for the three parameters (length, weight, head circumference) were performed and compared with the median for the National Center for Health Statistics (NCHS) curves. The median values for length, weight, and head circumference at birth and 6, 12, 18, and 24 months of age were plotted against NCHS median values and statistically compared at birth and 24 months. Setting: Hospital de Reabilitacao de Anomalias Craniofaciais, Universidade de Sao Paulo, Bauru, Brazil (HRAC-USP). Results: At birth, children of both genders with UCLP presented with smaller body dimensions in relation to NCHS median values, but the results suggest a catch-up growth for length, weight, and head circumference for girls and for weight (to some degree) and head circumference for boys. Conclusions: Weight was the most compromised parameter for both genders, followed by length and then head circumference. There was no evidence of short stature. This study established growth curves for children with UCLP.

Concretes and mortars recycled with water treatment sludge and construction and demolition rubble

There are about 7500 water treatment plants in Brazil. The wastes these plants generate in their decantation tanks and filters are discharged directly into the same brooks and rivers that supply water for treatment. Another serious environmental problem is the unregulated disposal of construction and demolition rubble, which increases the expenditure of public resources by degrading the urban environment and contributing to aggravate flooding and the proliferation of vectors harmful to public health. In this study, an evaluation was made of the possibility of recycling water treatment sludge in construction and demolition waste recycling plants. The axial compressive strength and water absorption of concretes and mortars produced with the exclusive and joint addition of these two types of waste was also determined. The ecoefficiency of this recycling was evaluated by determining the concentration of aluminum in the leached extract resulting from the solubilization of the recycled products. The production of concretes and mortars with the joint addition of water treatment sludge and recycled concrete rubble aggregates proved to be a viable recycling alternative from the standpoint of axial compression strength, modulus of elasticity, water absorption and tensile strength by the Brazilian test method. (C) 2008 Elsevier Ltd. All rights reserved.

Occurrence of wide-band tracheids in Cactaceae: wood variation during Pilosocereus auriasetus development

Studies of wide-band tracheids (WBTs) have aroused the interest of researchers who have searched to understand their origin, function, and phylogenetic implications. The present research has the objective of studying the distribution of WBTs, together with anatomic aspects of vegetative organs in different stages of Pilosocereus aurisetus, in order to understand the occurrence of WBTs in columnar cacti. Transverse and longitudinal sections of the stem (apex, middle, and base) and the root were made. The epidermis was present in the photosynthetic stem, but was substituted by periderm which was already well established in the root. The differentiation of the cortex is visible in the middle of the stem, becoming homogeneous in the base. WBTs were observed in the base and middle of young stems (WBT monomorphic wood); common in stems of globular cacti. However, WBTs/ fibrous dimorphic wood was observed in the base of adult stems, a result of the cambial activity producing vessel elements and fibers. This wood polymorphism of the Cactaceae can be interpreted as cambial variation, a common character of Caryophyllales. Due to the small size of the plant, the presence of WBTs in the young stem may be related to water retention necessary for its development, rather than to physical support of the plant.

Lignocellulosic polysaccharides and lignin degradation by wood decay fungi: the relevance of nonenzymatic Fenton-based reactions

The brown rot fungus Wolfiporia cocos and the selective white rot fungus Perenniporia medulla-panis produce peptides and phenolate-derivative compounds as low molecular weight Fe(3+)-reductants. Phenolates were the major compounds with Fe(3+)-reducing activity in both fungi and displayed Fe(3+)-reducing activity at pH 2.0 and 4.5 in the absence and presence of oxalic acid. The chemical structures of these compounds were identified. Together with Fe(3+) and H(2)O(2) (mediated Fenton reaction) they produced oxygen radicals that oxidized lignocellulosic polysaccharides and lignin extensively in vitro under conditions similar to those found in vivo. These results indicate that, in addition to the extensively studied Gloeophyllum trabeum-a model brown rot fungus-other brown rot fungi as well as selective white rot fungi, possess the means to promote Fenton chemistry to degrade cellulose and hemicellulose, and to modify lignin. Moreover, new information is provided, particularly regarding how lignin is attacked, and either repolymerized or solubilized depending on the type of fungal attack, and suggests a new pathway for selective white rot degradation of wood. The importance of Fenton reactions mediated by phenolates operating separately or synergistically with carbohydrate-degrading enzymes in brown rot fungi, and lignin-modifying enzymes in white rot fungi is discussed. This research improves our understanding of natural processes in carbon cycling in the environment, which may enable the exploration of novel methods for bioconversion of lignocellulose in the production of biofuels or polymers, in addition to the development of new and better ways to protect wood from degradation by microorganisms.

PERMEABILITY MEASUREMENTS OF BRAZILIAN PINUS ELLIOTTII

The liquid and gas phase permeability, of Brazilian Pinus elliotii was studied with a custom built gas and liquid flow rate analysis chamber. The longitudinal gas phase permeability is shown to be six times greater than the radial permeability. There is no statistically significant difference between the longitudinal permeability of water versus wood preservative. Scanning Electron Microscopy (SEM) images confirm that the reported permeability properties arc due to the wood itself rather than to blocked pores or other artifacts of the sample cutting process. Wood composition analysis shows that the samples of Pinus elliotii grown in Brazil are similar to other species of Pinus grown in tropical climates. Specifically, the Pinus elliotti in this study is composed of 17% extractives, 0,27% ashes, 21% hemicellulose, 45% cellulose and 30% lignin. Results arc discussed in the context of the continued search for effective wood preservatives for use in tropical climates.

Limiting factors for phytoplankton growth in subtropical reservoirs: the effect of light and nutrient availability in different longitudinal compartments

Limited information is available on the interactions between environmental factors and algal growth in tropical and subtropical aquatic systems. We investigated the relationships between algal biomass (measured as chlorophyll, Chl-a) and light, total phosphorus (TP) and total nitrogen (TN) in longitudinal zones of subtropical reservoirs. We studied the seasonal variation of water variables in Itupararanga Reservoir (Brazil) and compared the results with 16 other subtropical lakes and reservoirs. The longitudinal zones in Itupararanga Reservoir were considered statistically different (p 0.05, MANOVA). From the riverine zone to the dam region of the reservoir, Spearman Correlation Test suggested that light limitation and TP limitation tended to decrease and increase, respectively. Although nitrate concentrations were high (400 g/L), the Spearman coefficients between Chl-a and TN and the TN:TP ratios (11:1 TN:TP 35:1) indicated that nitrogen may be co-limiting algal growth in the studied water body. Putting Itupararanga in a regional context allowed assessment of potential influences of land use on trophic state. Within the subtropical dataset, TP explained a greater percentage of variance in Chl-a (R2 = 0.70) than TN (R2 = 0.17). The main land use type within the reservoirs drainage area significantly influenced the concentrations of TP, TN, and Chl-a (p 0.05, MANOVA), with different relationships between nutrients and chlorophyll in forested (R2 = 0.12-0.33), agricultural (R2 = 0.50-0.68) and urban (R2 = 0.09-0.64) watersheds. Comparisons with literature values and those from reservoirs with less altered watersheds indicated that Itupararanga Reservoir is reaching the mesotrophic-eutrophic boundary, and further nutrient enrichment could cause water quality degradation.

Changes in wood-water relationship due to heat treatment assessed on micro-samples of three Eucalyptus species

Wood-water relationship of untreated and heat-treated wood was studied. Specimens of Eucalyptus grandis, E saligna, and E citriodora were submitted to five conditions of heat treatment: 180 degrees C and 220 degrees C with air; 220 degrees C, 250 degrees C, and 280 degrees C with N(2). The wood-water relationships were accurately studied in a special device, in which the moisture content (MC) of the sample was measured with a highly sensitive electronic microbalance placed in a climatic chamber. The dimensions of the sample were collected continuously without contact by means of two high-speed laser scan micrometers. Sorption curves and shrinkage-MC relationships were observed. To study the effects of heat treatment, the following parameters were also determined: fiber saturation point (FPS), wood anisotropy (T/R ratio), shrinkage slope, reduction in hygroscopicity, and anti-shrink efficiency (ASE). The physical properties were significantly affected only at 220 degrees C and above. At heat temperature levels higher than 220 degrees C, the reduction in hygroscopicity and ASE are higher than 40% and continue to be reduced with increasing temperature level. This work also demonstrates that heat treatment does not change the slope of the curves shrinkage vs. MC, proving that heat treatment affects the domain of alterations in wood properties, but not the behavior within this domain.

Variation of wood density and relationship with the tree-ring width of mahogany trees, Swietenia macrophylla, from Amazonian tropical forest of Peru

Mahogany trees, Swietenia macrophylla, occur in open rainforest, semi deciduous and deciduous and dense rainforest of Peruvian Amazonian tropical forest. They occur, preferentially, in areas with a defined dry season, with typical phenology and seasonal variation activity, forming distinct tree-rings. The present work had as aim to determine the wood density radial variation of 14 mahogany trees, of two populations of the Peruvian Amazonian tropical forest, through the X-ray densitometry and to evaluate their application as methodology, compared to the classic method of measurement table, for the determination of the treering width. The radial wood apparent density of the trees profiles rendered it possible to delimit the areas of juvenile-adult wood and of the heartwood-sapwood, relative to the anatomical structure and chemical composition differences, due to the extractives and the vessels obstruction by tyloses. The mean, minimum and maximum wood apparent density of the mahogany trees for the Populations A and B were of 0.70; 0.29; 1.01 g.cm(-3) and 0.81; 0.29; 1.19 g.cm(-3), respectively. The analysis of the variance and mean test indicate differences of mean wood density among the mahogany trees of each population, probably due to the age of the trees. There was no correlation between mean wood density of mahogany trees among the two populations, as well as, between the tree-ring width and the respective mean density. The X-ray densitometry technique is an important tool in the evaluation of the radial variation of wood apparent density and the delimitation of tree-ring boundaries, with correlations of 0.94 and 0.93 in relation to measurement table, for each sampled population.

NMR imaging of fluid pathways during drainage of softwood in a pressure membrane chamber

An experiment was implemented to study fluid flow in a pressure media. This procedure successfully combines nuclear magnetic resonance imaging with a pressure membrane chamber in order to visualize the non-wetting and wetting fluid flows with controlled boundary conditions. A specially designed pressure membrane chamber, made of non-magnetic materials and able to withstand 4 MPa, was designed and built for this purpose. These two techniques were applied to the drainage of Douglas fir sapwood. In the study of the longitudinal flow, narrow drainage fingers are formed in the latewood zones. They follow the longitudinal direction of wood and spread throughout the sample length. These fingers then enlarge in the cross-section plane and coalesce until drainage reaches the whole latewood part. At the end of the experiments, when the drainage of liquid water in latewood is completed, just a few sites of percolation appear in earlywood zones. This difference is a result of the wood anatomical structure, where pits, the apertures that allow the sap to flow between wood cells, are more easily aspirated in earlywood than in latewood. (C) 2007 Elsevier Ltd. All rights reserved.

Adhesion of an endodontic sealer to dentin and gutta-percha: shear and push-out bond strength measurements and SEM analysis

The use of an adequate method for evaluation of the adhesion of root canal filling materials provides more reliable results to allow comparison of the materials and substantiate their clinical choice. The aims of this study were to compare the shear bond strength (SBS) test and push-out test for evaluation of the adhesion of an epoxy-based endodontic sealer (AH Plus) to dentin and gutta-percha, and to assess the failure modes on the debonded surfaces by means of scanning electron microscopy (SEM). Three groups were established (n=7): in group 1, root cylinders obtained from human canines were embedded in acrylic resin and had their canals prepared and filled with sealer; in group 2, longitudinal sections of dentin cylinders were embedded in resin with the canal surface smoothed and turned upwards; in group 3, gutta-percha cylinders were embedded in resin. Polyethylene tubes filled with sealer were positioned on the polished surface of the specimens (groups 2 and 3). The push-out test (group 1) and the SBS test (groups 2 and 3) were performed in an Instron universal testing machine running at crosshead speed of 1 mm/min. Means (±SD) in MPa were: G1 (8.8±1.13), G2 (5.9±1.05) and G3 (3.8±0.55). Statistical analysis by ANOVA and Student's t-test (a=0.05) revealed statistically significant differences (p<0.01) among the groups. SEM analysis showed a predominance of adhesive and mixed failures of AH Plus sealer. The tested surface affected significantly the results with the sealer reaching higher bond strength to dentin than to gutta-percha with the SBS test. The comparison of the employed methodologies showed that the SBS test produced significantly lower bond strength values than the push-out test, was skilful in determining the adhesion of AH Plus sealer to dentin and gutta-percha, and required specimens that could be easily prepared for SEM, presenting as a viable alternative for further experiments.

Assessment of simulated mandibular condyle bone lesions by cone beam computed tomography

There are many limitations to image acquisition, using conventional radiography, of the temporomandibular joint (TMJ) region. The Computed Tomography (CT) scan is a better option, due to its higher accuracy, for purposes of diagnosis, surgical planning and treatment of bone injuries. The aim of the present study was to analyze two protocols of cone beam computed tomography for the evaluation of simulated mandibular condyle bone lesions. Spherical lesions were simulated in 30 dry mandibular condyles, using dentist drills and drill bits sizes 1, 3 and 6. Each of the mandibular condyles was submitted to cone beam computed tomography (CBCT) using two protocols: 1) axial, coronal and sagittal multiplanar reconstruction (MPR); and 2) sagittal plus coronal slices throughout the longitudinal axis of the mandibular condyles. For these protocols, 2 observers analyzed the CBCT images independently, regarding the presence or not of injuries. Only one of the observers, however, performed on 2 different occasions. The results were compared to the gold standard, evaluating the percentage of agreement, degree of accuracy of CBCT protocols and observers' examination. The z test was used for the statistical analysis. The results showed there were no statistically significant differences between the 2 protocols. There was greater difficulty in the assessment of small-size simulated lesions (drill # 1). From the results of this study, it can be concluded that CBCT is an accurate tool for analyzing mandibular condyle bone lesions, with the MPR protocol showing slightly better results than the sagittal plus coronal slices throughout the longitudinal axis.

Estudo longitudinal da compreensão verbal de crianças usuárias de implante coclear

OBJETIVO: analisar a compreensão verbal de crianças surdas usuárias de implante coclear (IC) por meio de um estudo longitudinal. MÉTODOS: os participantes foram nove crianças surdas usuárias de IC. A idade cronológica das crianças variou entre quatro e oito anos e o tempo de uso do IC foi, em média, 1 ano e 6 meses na 1ª avaliação, 3 anos e 7 meses na 2ª avaliação e 4 anos e 9 meses na 3ª avaliação. As crianças foram avaliadas longitudinalmente por meio da Escala de Compreensão Verbal da RDLS. Os materiais usados foram brinquedos, objetos e figuras. Os dados foram analisados qualitativa e quantitativamente. RESULTADOS: os resultados mostraram que as crianças implantadas obtiveram uma evolução estatisticamente significante em relação às habilidades de linguagem receptiva. CONCLUSÃO: o estudo comprova a efetividade do IC para o desenvolvimento da compreensão verbal.

Evolution of magnetic properties and crystallographic texture in electrical steel with large plastic deformation

Deformation leads to a hardening of steel due to an increase in the density of dislocations and a reduction in their mobility, giving rise to a state of elevated residual stresses in the crystal lattice. In the microstructure, one observes an increase in the contribution of crystalline orientations which are unfavorable to the magnetization, as seen, for example, by a decrease in B(50), the magnetic flux density at a field of 50 A/cm. The present study was carried out with longitudinal strips of fully processed non-oriented (NO) electrical steel, with deformations up to 70% resulting from cold rolling in the longitudinal direction. With increasing plastic deformation, the value of B(50) gradually decreases until it reaches a minimum value, where it remains even for larger deformations. On the other hand, the coercive field H(c) continually increases. Magnetometry results and electron backscatter diffraction results are compared and discussed. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3560895]