Comparação entre valores de ensaios experimentais e calculados da resistência ao embutimento da madeira de Pinus taeda L.

To design connections between timber parts with metal dowels (nails or bolts), two phenomena must be considered: bending of the metal dowel and the embedment strength in the wood. The Brazilian Standard ABNT NBR 7190:1997 proposes the methods used in the laboratory tests to determine the embedment strength with the metal dowell and, in the absence of testing, specifies relations to calculate the embedment strength from the compression strength. The aim of this research was to compare the embedment strength values obtained by experimental tests and calculated by the relationships established by the Brazilian Standard ABNT NBR 7190:1997. By the results of the hypothesis tests, it was possible to conclude that the estimate of the embedment strength parallel to the grain proposed by the Brazilian standard ABNT NBR 7190:1997, establishing equivalence with the strength compression results in the same direction, must be effective to the wood species Pinus taeda L., however, the same was not found in the perpendicular direction with respect to the grain, possibly explained by the alpha(e) values in the equation to calculed fe(90)

Sinais digitais de um durômetro portátil para a estimativa de propriedades de madeiras para dormentes

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Which kind of miniplate to use in mandibular sagittal split osteotomy? An in vitro study

This study verified the resistance to displacement of six miniplate fixation methods after sagittal split osteotomy (SSO). SSO was performed in 30 polyurethane synthetic mandible replicas. The distal segments were advanced (4 mm) and specimens were grouped according to the fixation method: four-hole standard miniplate; four-hole locking miniplate; six-hole standard miniplate; six-hole locking miniplate; six-hole standard sagittal miniplate; six-hole locking sagittal miniplate. Biomechanical evaluation was performed by applying compression loads to three points on the second molar region, using an Instron universal testing machine until a 3 mm displacement of the segments occurred. Compression loads able to produce 3 mm displacement were recorded in kN and subjected to analysis of variance (P < 0.01) and Tukey's tests for comparison between groups (P < 0.05). The locking sagittal miniplate showed higher resistance to displacement than the regular four- and six-hole locking and standard miniplates. No significant differences were observed between the locking sagittal miniplate and the regular sagittal or the four-hole locking miniplates. Two of the three groups with the best results had locking plate fixation methods. Fixation of SSO with a single miniplate is better accomplished using six-hole locking sagittal miniplates, six-hole standard sagittal miniplates, or four-hole locking miniplates; these methods are more resistant to displacement.

Lignin from sugar cane bagasse: Extraction, fabrication of nanostructured films, and application

Four lignin samples were extracted from sugar cane bagasse using four different alcohols (methanol, ethanol, n-propanol, and 1-butanol) via the organosolv-CO2 supercritical pulping process. Langmuir films were characterized by surface pressure vs mean molecular area (Pi-A) isotherms to exploit information at the molecular level carrying out stability tests, cycles of compression/expansion (hysteresis), subphase temperature variations, and metallic ions dissolved into the water subphase at different concentrations. Briefly, it was observed that these lignins are relatively stable on the water surface when compared to those obtained via different extraction processes. Besides, the Pi-A isotherms are shifted to smaller molecular areas at higher subphase temperatures and to larger molecular areas when the metallic ions are dissolved into the subphase. The results are related to the formation of stable aggregates (domains) onto the water subphase by these lignins, as shown in the Pi-A isotherms. It was found as well that the most stable lignin monolayer onto the water subphase is that extracted with 1-butanol. Homogeneous Langmuir-Blodgett (LB) films of this lignin could be produced as confirmed by UV-vis absorption spectroscopy and the cumulative transfer parameter. In addition, FTIR analysis showed that this lignin LB film is structured in a way that the phenyl groups are organized preferentially parallel to the substrate surface. Further, these LB films were deposited onto gold interdigitated electrodes and ITO and applied in studies involving the detection of Cd+2 ions in aqueous solutions at low concentration levels throughimpedance spectroscopy and electrochemical measurements. FTIR spectroscopy was carried out before and after soaking the thin films into Cd+2 aqueous solutions, revealing a possible physical interaction between the lignin phenyl groups and the heavy metal ions. The importance of using nanostructured systems is demonstrated as well by comparing both LB and cast films.

Alternative saline solutions to float foraminiferal tests

Flotation has been widely used in studies of recent foraminifera in order to concentrate tests and save time during picking. In this paper, four flotation agents with different densities were compared: (1) trichloroethylene, TCE (C2HCl3), with a density of 1.46 g mL(-1); (2) sodium nitrate/sodium thiosulfate solution, SNT (NaNO3 + Na2O3S2 center dot 5H(2)O), with a density of 1.46 g mL(-1); (3) zinc chloride Solution, ZC (ZHCl(2)), with a density of 1.70 g mL(-1); and (4) sodium polytungstate solution, SPT (3Na(2)WO(4) center dot 9WO(3) center dot 5H(2)O), with a density of 2.50 g mL(-1). Comparison was carried out by means of qualitative and quantitative data. Results showed that ZC and SPT were the best flotation agents, recovering 91% and 96% of the total tests, respectively, whereas TCE and SNT recovered 59.1% and 72.8%, respectively. Both quantitative and qualitative results significantly improved with a higher density of the flotation liquid. Therefore, substitution of TCE with ZC or SPT solutions is strongly encouraged, because they are, additionally, less harmful to health and the environment. ZC is the most cost-effective, since its results were not significantly different from those of the SPT treatment. Carbon tetrachloride (CCl4) was not considered in this comparative study, because it has been banned in many countries and it is highly harmful to health and the environment.

AMS and grain shape fabric of the Late Palaeozoic diamictites of the Southeastern Paran Basin, Brazil

Diamictites interbedded with marine shales and turbidites onlap the eastern border of the Parana Basin (Southern Brazil). These poorly sorted sediments were deposited during the Permo-Carboniferous glaciation, and their matrix-supported clasts show no preferred orientation. These massive rocks have been studied using anisotropy of magnetic susceptibility (AMS) and grain shape fabric. Hysteresis loops and thermomagnetic measurements show that AMS depends mostly on the paramagnetic clays, but fine ferromagnetic particles also contribute to the anisotropy. The coarse silt to sand grain preferred orientation study supports the use of AMS in describing the diamictite fabric, at least regarding the orientation of the foliation. AMS and grain shape data reveal subhorizontal to weakly inclined magnetic and grain shape foliation parallel to the regional bedding. The magnetic lineations are normally scattered within the foliation plane in agreement with the oblate AMS ellipsoids found in these rocks. Both fabric patterns are consistent with deposition by subaqueous mudflows that were resedimented downslope, with elastic supply from continental sources. The off-vertical grain shape foliation poles suggest that the deposition of diamictites was controlled by the depocentre topography of the Rio do Sul sub-basin.

Structural behaviour of three-pile caps subjected to axial compressive loading

This work presents a comparative analysis about the behaviour of pile caps supported by 3 piles subjected to axial loading. Piles with 20 cm and 30 cm diameters were analysed. The main reinforcement was maintained in all the specimens, however, the arrangement of the secondary reinforcement varied. The main reinforcement consisted of steel bars connecting the piles. The secondary reinforcement was made up of: (a) bars going through the piles and through the projection of the column, (b) bars forming a network, and (c) vertical and horizontal stirrups. The main objective was the observation of the pile cap behaviour regarding the cracks and the modes of rupture. The real scale specimens were subjected to experimental tests until failure by rupture. Instruments were placed with the aim to obtain the displacement of the bases, the strains in the main and secondary reinforcement bars, in the compression struts, in the lower and upper nodal zones and in the sides of the caps. None of the caps reached failure by rupture with a load less than 1.12 times the theoretical load. The specimens ruptured due to the cracking of the compression strut and/or the yielding of the reinforcement bars in one direction.

Condutividade hidráulica saturada e direcional em xisto: ensaios em laboratório. -

Pós-graduação em Geociências e Meio Ambiente - IGCE

Physiological responses of the brown mussel Perna perna (Mollusca, Bivalvia) exposed to the anionic surfactant linear alkylbenzene sulphonate (LAS).

The effects of the Linear Alkylbenzene Sulphonate (LAS) were evaluated on the mussel Perna perna, using physiological and genotoxic biomarkers. The Micronuclei (MN) assay was used to estimate effects at nuclear level, whereas the physiological effects were evaluated by measuring the oxygen consumption and ammonia excretion rates. Significant effects were observed for the MN assay and the ammonia excretion rate, even in low concentrations. The oxygen consumption was not affected in the tested concentrations. For MN and ammonia excretion, the animals exposed to intermediate concentrations were not affected, but responded to the higher concentrations, indicating the existence of compensatory mechanisms at physiological level. However, parallel to this study other authors indicate the presence of progressive effects at the cellular level, suggesting that the organisms are not capable to recover of such increasing effects. Additionally, the results show that the levels of LAS observed for Brazilian coastal waters may chronically affect the biota.

Fine root isotropy in Eucalyptus grandis plantations. Towards the prediction of root length densities from root counts on trench walls

The objectives of the study were to assess changes in fine root anisotropy and specific root lengths throughout the development of Eucalyptus grandis ( W. Hill ex Maiden) plantations and to establish a predictive model of root length density (RLD) from root intercept counts on trench walls. Fine root densities (<1 mm in diameter) were studied in 6-, 12-, 22-, 28-, 54-, 68- and 72-month-old E. grandis plantations established on deep Ferralsols in southern Brazil. Fine root intercepts were counted on 3 faces of 90-198 soil cubes (1 dm(3) in volume) in each stand and fine root lengths (L) were measured inside 576 soil cubes, sampled between the depths of 10 cm and 290 cm. The number of fine root intercepts was counted on one vertical face perpendicular to the planting row (N(t)), one vertical face parallel to the planting row (N(l)) and one horizontal face (N(h)), for each soil cube sampled. An overall isotropy of fine roots was shown by paired Student's t-tests between the numbers of fine roots intersecting each face of soil cubes at most stand ages and soil depths. Specific root lengths decreased with stand age in the upper soil layers and tended to increase in deep soil layers at the end of the rotation. A linear regression established between N(t) and L for all the soil cubes sampled accounted for 36% of the variability of L. Such a regression computed for mean Nt and L values at each sampling depth and stand age explained only 55% of the variability, as a result of large differences in the relationship between L and Nt depending on stand productivity. The equation RLD=1.89*LAI*N(t), where LAI was the stand leaf area index (m(2) m(-2)) and Nt was expressed as the number of root intercepts per cm(2), made it possible to predict accurately (R(2)=0.84) and without bias the mean RLDs (cm cm(-3)) per depth in each stand, for the whole data set of 576 soil cubes sampled between 2 years of age and the end of the rotation.

Prediction of Soil Properties from the Concepts of Energy Transfer in Dynamic Penetration Tests

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of methyl methacrylate monomer on bond strength of denture base resin to acrylic teeth

Bond failures at the acrylic teeth and denture base resin interface are still a common clinical problem in prosthodontics. The effect of methyl methacrylate (MMA) monomer on the bond strength of three types of denture base resins (Acron MC, Lucitone 550 and QC-20) to two types of acrylic teeth (Biotone and Trilux) was evaluated. Twenty specimens were produced for each denture base resin/acrylic tooth combination and were randomly divided into control (acrylic teeth received no surface treatment) and experimental groups (MMA was applied to the surface of the acrylic teeth for 180 s) and were submitted to shear tests (1 mm/mm). Data (MPa) were analyzed using three-way ANOVA/Student's test (alpha = 0.05). MMA increased the bond strength of Lucitone denture base resins and decreased the bond strength of QC-20. No difference was detected for the bond strength of Acron MC base resin after treatment with MMA. (C) 2008 Elsevier Ltd. All rights reserved.

Influence of oxygen flow on crystallization and morphology of LiNbO3 thin films

Polymeric precursor solution (Pechini method) was used to deposit LiNbO3 thin films by spin-coating on (100) silicon substrates. X-ray diffraction data of thin films showed that the increase of oxygen flow promotes a preferred orientation of (001) LiNbO3 planes parallel to the substrate surface. Surface roughness and grain size, observed by atomic force microscopy, change also with oxygen flow.

Relationship between grain-boundary capacitance and bulk shallow donors in SnO2 polycrystalline semiconductor

The relationship between grain-boundary capacitance and extrinsic shallow donors caused by Nb addition to SnO2 center dot COO binary polycrystalline system has been investigated by means of combined techniques such as I-V characteristic response, complex impedance and capacitance analysis and electrostatic force microscopy. The estimated role of the Nb doping is to increase the concentration of shallow donors that are capable of enhancing the electronic donation to grain-boundary acceptors. This effect leads to the formation of potential barriers at grain boundaries with a simultaneous increase of grain-boundary capacitance and non-Ohmic features of the polycrystalline device doped with Nb atoms.

End-to-side neurorrhaphy with and without perineurium

OBJETIVOS: Comparar a neurorrafia término-lateral com epineuro versus sem epineuro. DESENHO: Foram operados 20 ratos. O nervo fibular foi seccionado e seu coto distal suturado na face lateral do nervo tibial. do lado direito nós removemos janela de epineuro e no lado esquerdo o epineuro foi deixado intacto. Depois de seis meses, os 14 animais sobreviventes foram submetidos a testes eletrofisiológicos, sacrificados e os nervos e músculos removidos para exames histológicos. O teste eletrofisiológico foi realizado mediante estímulo elétrico fornecido por um neuro-estimulador (LHM-110) com 2 milisegundos de duração, num modo repetido e 30 Hz. O estímulo foi aumentado progressivamente partindo de zero até atingir 1 volt. LOCAL: Faculdade de Medicina de Botucatu. RESULTADOS: No lado direito, os músculos que tiveram resposta positiva necessitaram uma média de 258,89 mv (±92,31) de estímulo elétrico para apresentar uma resposta e no lado esquerdo uma média de 298,34 mV (±139,32). O músculo tibial cranial apresentou peso médio para o lado direito de 0,47 g (±0,18) e para o lado esquerdo de 0,45 g (±0,15). O coto distal do nervo fibular apresentou uma média 310 fibras nervosas (±191,34) para o lado direito e 287,71 (±183,60) para o lado esquerdo. O nervo tibial acima da neurorrafia mostrou médias de 939,46 (±223,51) fibras nervosas para o lado direito e 959,46 (±327,48) para o lado esquerdo. O nervo tibial abaixo da neurorrafia mostrou médias de 935,17 (±298,65) fibras nervosas para o lado direito e 755,31 (±323,26) para o lado esquerdo. As fibras do músculo tibial cranial do lado direito apresentaram uma área média de 0,0162 (±0,008) m2 depois de 230 vezes de magnificação e 0,0152 (±0,0064) para as fibras do músculo tibial cranial do lado esquerdo. O aspecto histológico do músculo tibial cranial, tomando-se o normal como 100% foi de 78,21 (±20,75) para o lado direito e 82,14 (±15,89) para o lado esquerdo. A análise estatística (testetde Student) não mostrou diferenças (p>0,05) entre os lados esquerdo e direito para todas as variáveis. CONCLUSÕES: Ambas as neurorrafias (com e sem epineuro) não mostraram diferenças relacionadas aos aspectos morfológicos e eletrofisiológicos estudados.