Evaluation of the components of production of the ricinus according of rates of calcareous rock and match

The soil of the Paraiba, in generality, are acid and with low levels of available match, seriously limiting the income of the plants. A research in vegetation house was lead, with the objective to evaluate doses of calcareous soil and match in the culture of ricinus. The treatments had been composites for five levels of match: 0.0; 80; 160; 240 and 360 kg ha(-1) of P(2)O(5) and four dosis of calcareous rock: 0.0; 2.5; 3.5 and 4.5 t ha(-1) in experimental delineation of blocks casualized with 4 factorial project x 3 (four levels of match and three doses of calcareous soil) more two treatments you add zero of match (0.0 P(2)O(5): 2,5 t ha(-1) of calcareous soil) and calcareous soil zero (240 P(2)O(5): 0.0 t ha(-1) of calcareous soil), with three repetitions. The calcareous soil reduced the acidity of the ground and effect of the application of the match (>= 80 kg ha(-1) of P(2)O(5)) in the presence of the collagen (>= 2.5 t ha(-1) of CaCO(3)) with of the calcareous soil (>= 2.5 t ha(-1) of CaCO(3)) in the presence of the match was not verified well (>= 80 kg ha(-1) of P(2)O(5)). The match applied in the absence of the calcareous soil was limited to the income of the culture of what the calcareous soil in the absence of the match.

Shear strength evaluation of composite-composite resin associations

Objective: The aim of this study was to investigate the shear strength between distinct associations of different commercial composite resins and their fracture modes.Methods: Nine composite-composite associations (n = 90) were prepared for shear strength evaluation and separated into the following groups: Z/Z (Filtek Z250 UD + Filtek Z250 A2); Z/ D (Filtek Z250 UD + Durafill VS A2); Z/S (Filtek Z250 UD + Filtek Supreme YT); C/C (Charisma OA2 + Charisma A2); C/D (Charisma OA2 + Durafill VS A2); C/S (Charisma OA2 + Filtek Supreme YT); H/H (Herculite XRV B2D + Herculite XRV B2E); H/D (Herculite XRV B2D + Durafill VS A2); H/S (Herculite XRV B2D + Filtek Supreme YT). Shear tests were carried out using universal mechanical test equipment with a load of 200 kgf and speed of 0.5 mm/min. Ultimate shear strength data (MPa) from all tested groups were submitted to analysis of variance (one-way ANOVA) and the Tukey test. The fractured surfaces of the test samples were visually evaluated by binocular stereomicroscope at 20 times magnification. Fractures were classified as either adhesive or cohesive or mixed.Results: The highest ultimate shear strength observed for composite-composite associations was found for the groups: Z/Z, C/S, H/H, H/S, Z/S and C/C. Those associations containing the Durafill resin were weaker than the others.Conclusion: Microparticle RBC associations presented lower shear strength than hybrid and/or nanoparticle RBC associations, once the only significant difference was found when the Durafill resin was involved. (c) 2008 Elsevier Ltd. All rights reserved.

Analysis of bone microarchitecture related to anthropometry in climateric women

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

An AM1 semiempirical study of the mechanism of sintering for ZnO in the presence of water and carbon dioxide

AM1 calculations were performed for the absorption of H2O and CO2 molecules on the surface of model ZnO crystals. The absorption of isolated molecules of each species and the co-absorption of both compounds simultaneously were considered. It was found that the absorption of H2O near a site where CO; is already absorbed favors the process of sintering, in agreement with the experimental findings. This is explained by the formation of Zn(OH)CO3H bound to the surface, a more mobile species than the ZnO unit itself. The roundening of the grains observed in atmospheres containing dry CO2 but suppressed when H2O is present, is also explained by these calculations. After absorption of CO2, the rupture of one bond - so that diffusion of the ZnCO3 species on the surface is allowed - requires much less energy than the breaking of two bonds, necessary for ZnO migration. These facts explain why the speed of surface transport does not decrease in CO2 atmospheres while sintering is indeed slowed down. © 1994.

SAXS measurements of the porosity in Cu(II)-doped SnO2 xerogels during crystallization

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Correlation of electrical conductivity and other vigor tests with field emergence of soybean seedlings

Seeds from six soybean cultivars (Cristalina, IAC 31-Foscarin, IAC-15, UFV-10, IAC-14 and IAS-5) and from five soybean cultivars (IAC 31-Foscarin, IAC-15, IAC-14, IAS-5 and Iguacu) were evaluated in 1993 and 1994, respectively, in terms of physiological seed quality by the mechanical damage (MD), standard germination (SG), accelerated aging (AA), electrical conductivity (EC), and seedling field emergence (FE) tests. Significant correlations were detected between SG, AA and EC and FE. However, in terms of the cultivar or the year, the degree of association among these parameters can change based on the environmental conditions of each year.

Effect of Surface Treatments on the Bond Strength between Composite Resin and Acrylic Resin Denture Teeth

Purpose: This investigation studied the effects of 3 surface treatments on the shear bond strength of a light-activated composite resin bonded to acrylic resin denture teeth. Materials and Methods: The occlusal surfaces of 30 acrylic resin denture teeth were ground flat with up to 400-grit silicon carbide paper. Three different surface treatments were evaluated: (1) the flat ground surfaces were primed with methyl methacrylate (MMA) monomer for 180 seconds; (2) light-cured adhesive resin was applied and light polymerized according to the manufacturer's instructions; and (3) treatment 1 followed by treatment 2. The composite resin was packed on the prepared surfaces using a split mold. The interface between tooth and composite was loaded at a cross-head speed of 0.5 mm/min until failure. Results: Analysis of variance indicated significant differences between the surface treatments. Results of mean comparisons using Tukey's test showed that significantly higher shear bond strengths were developed by bonding composite resin to the surfaces that were previously treated with MMA and then with the bonding agent when compared to the other treatments. Conclusion: Combined surface treatment of MMA monomer followed by application of light-cured adhesive resin provided the highest shear bond strength between composite resin and acrylic resin denture teeth.

Friction and wear properties of functionally graded aluminum matrix composites

Aluminum matrix composites are currently considered as promising materials for tribological applications in the automotive, aircraft and aerospace industries due to their great advantage of a high strength-to-weight ratio. A superior combination of surface and bulk mechanical properties can be attained if these composites are processed as functionally graded materials (FGM's). In this work, homogeneous aluminum based matrix composite, cast by gravity, and aluminum composites with functionally graded properties, obtained by centrifugal cast, are tested against nodular cast iron in a pin-on-disc tribometer. Three different volume fractions of SiC reinforcing particles in each FGM were considered in order to evaluate their friction and wear properties. The sliding experiments were conducted without lubrication, at room temperature, under a normal load of 5 N and constant sliding speed of 0.5 ms-1. The worn surfaces as well as the wear debris were characterized by SEM/EDS and by atomic force microscopy (AFM). The friction coefficient revealed a slightly decrease (from 0.60 to 0.50) when FGM's are involved in the contact instead of the homogeneous composite. Relatively low values of the wear coefficient were obtained for functionally graded aluminum matrix composites (≈10-6 mm3N-1 m-1), which exhibited superior wear resistance than the homogeneous composite and the opposing cast iron surface. Characterization of worn surfaces indicated that the combined effect of reinforcing particles as load bearing elements and the formation of protective adherent iron-rich tribolayers has a decisive role on the friction and wear properties of aluminum matrix composites.

Effect of ceramic surface treatment on the microtensile bond strength between a resin cement and an alumina-based ceramic

Purpose: The objective of this study was to test the following hypothesis: the silica coating on ceramic surface increases the bond strength of resin cement to a ceramic. Materials and Methods: In-Ceram Alumina blocks were made and the ceramic surface was treated: G1 - sandblasting with 110-μm aluminum oxide particles; G2 - Rocatec System: tribochemicai silica coating (Rocatec-Pre powder + Rocatec-Plus powder + Rocatec-Sil); G3 - CoJet System: silica coating (CoJet-Sand) + ESPE-Sil. The ceramic blocks were cemented to composite blocks with Panavia F resin cement (under a load of 750 g/1 min). The cemented blocks were stored in distilled water at 37°C for 7 days and sectioned along the x and y axes with a diamond disk. Samples with an adhesive area of ca 0.8 mm 2 (n = 45) were obtained. The samples were attached to an adapted device for the microtensile test, which was performed in a universal testing machine (EMIC) at a crosshead speed of 1 mm/min. Results: The obtained results were submitted to ANOVA and Tukey's test. Mean values of tensile strength (MPa) and standard deviation values were: (G1) 16.8 ± 3.2; (G2) 30.6 ± 4.5; (G3) 33.0 ± 5.0. G2 and 63 presented greater tensile strength than G1. There was no significant difference between G2 and G3. All the failures took place at the ceramic/resin cement interface. Conclusion: The silica coating (Rocatec or CoJet systems) of the ceramic surface increased the bond strength between the Panavia F resin cement and alumina-based ceramic.

Polymer light emitting devices with Langmuir Blodgett (LB) films of a polyfluorene derivative

Polyfluorenes are promising materials for the emitting layer of polymer light emitting devices (PLEDs) with blue emission. In this work, we report on PLEDs fabricated with Langmuir-Blodgett (LB) films of a polyfluorene derivative, namely poly(9,9-di-hexylfluorenediyl vinylene-alt-1,4-phenylenevinylene) (PDHF-PV). Y-type LB films were transferred onto ITO substrates at a surface pressure of 35 mN m-1 and with dipping speed of 3 mm min -1. A thin aluminum layer was evaporated on top of the LB film, thus yielding a sandwich structure (ITO/PDHF-PV(LB)/Al). Current-voltage (I vs V) measurements indicate that the device displays a classical behavior of a rectifying diode. The threshold value is approximately 5 V, and the onset for visible light emission occurs at ca. 10 V. From the a.c. electrical responses we infer that the active layer has a typical behavior of PLEDs where the real component of ac conductivity obeys a power-law with the frequency. Cole-Cole plots (Im(Z) vs. Re(Z)) for the device exhibit a series of semicircles, the diameter of which decreases with increasing forward bias. This PLED structure is modeled by a parallel resistance and capacitance combination, representing the dominant mechanisms of charge transport and polarization in the organic layer, in series with a resistance representing the ITO contact. Overall, the results presented here demonstrate the feasibility of LEDs made with LB films of PDHF-PV.

Global analysis of aerodynamics deflectors efficiency in the grinding process

The conventional, grinding methods in some cases are not very efficient because the arising of thermal damages in the pieces is very common. Optimization methods of cutting fluid application in the grinding zone are essential to prevent thermal problems from interaction of the wheel grains with the workpiece. surface. The optimization can happen through the correct selection of the cut parameters and development of devices that eliminate air layer effects generated around the grinding wheel. This article will collaborate with the development of an experimentation methodology which allows evaluating, comparatively, the performance of the deflectors in the cutting region to minimize the air layer effect of the high speed of the grinding wheel. The air layers make the cutting fluid jet to dissipate in the machine. An optimized nozzle was used in order to compare the results with the conventional method (without baffles or deflectors) of cutting fluid application. The results showed the high eficciency of the deflectors or baffles in the finish results. Copyright © 2006 by ABCM.

Installation of a getter vacuum pump in cathode-anode region of a high-power klystron amplifier - Propose and feasible

The possibility to install a getter vacuum pump and its feasible in the anode of a high-power klystron amplifier is investigated in order to decrease of the pressure in the gun and consequently increasing its lifetime. The study is conducted using a 1.3 GHz, 100 A and 240 kV high-power klystron with five reentrant coaxial cavities, assembled in a cylindrical drift tube 1.2 m long. This work takes into account the specific conductance of components of gun and all important gas sources, like the degassing of the drift tube, the cavity walls, the cathode, the anode, and the collector, as well the position and pumping speed of the getter vacuum pump in anode region. © 2006 IEEE.

Bond strength of adhesive systems to human tooth enamel

The purpose of this study was to evaluate in vitro three adhesive systems: a total etching single-component system (G1 Prime & Bond 2.1), a self-etching primer (G2 Clearfil SE Bond), and a self-etching adhesive (G3 One Up Bond F), through shear bond strength to enamel of human teeth, evaluating the type of fracture through stereomicroscopy, following the ISO guidance on adhesive testing. Thirty sound premolars were bisected mesiodistally and the buccal and lingual surfaces were embedded in acrylic resin, polished up to 600-grit sandpapers, and randomly assigned to three experimental groups (n = 20). Composite resin cylinders were added to the tested surfaces. The specimens were kept in distilled water (37°C/24 h), thermocycled for 500 cycles (5°C-55°C) and submitted to shear testing at a crosshead speed of 0.5 mm/min. The type of fracture was analyzed under stereomicroscopy and the data were submitted to Anova, Tukey and Chi-squared (5%) statistical analyses. The mean adhesive strengths were G1: 18.13 ± 6.49 MPa, (55% of resin cohesive fractures); G2: 17.12 ± 5.80 MPa (90% of adhesive fractures); and G3: 10.47 ± 3.14 MPa (85% of adhesive fractures). In terms of bond strength, there were no significant differences between G1 and G2, and G3 was significantly different from the other groups. G1 presented a different type of fracture from that of G2 and G3. In conclusion, although the total etching and self-etching systems presented similar shear bond strength values, the types of fracture presented by them were different, which can have clinical implications.

The effect of different light-curing units on tensile strength and microhardness of a composite resin

The aim of this study was to evaluate the influence of different light-curing units on the tensile bond strength and microhardness of a composite resin (Filtek Z250 - 3M/ESPE). Conventional halogen (Curing Light 2500 - 3M/ESPE; CL) and two blue light emitting diode curing units (Ultraled - Dabi/Atlante; UL; Ultrablue IS - DMC; UB3 and UB6) were selected for this study. Different light intensities (670, 130, 300, and 600 mW/cm2, respectively) and different curing times (20s, 40s and 60s) were evaluated. Knoop microhardness test was performed in the area corresponding to the fractured region of the specimen. A total of 12 groups (n=10) were established and the specimens were prepared using a stainless steel mold composed by two similar parts that contained a cone-shaped hole with two diameters (8.0 mm and 5.0 mm) and thickness of 1.0 mm. Next, the specimens were loaded in tensile strength until fracture in a universal testing machine at a crosshead speed of 0.5 mm/min and a 50 kg load cell. For the microhardness test, the same matrix was used to fabricate the specimens (12 groups; n=5). Microhardness was determined on the surfaces that were not exposed to the light source, using a Shimadzu HMV-2 Microhardness Tester at a static load of 50 g for 30 seconds. Data were analyzed statistically by two-way ANOVA and Tukey's test (p<0.05). Regarding the individual performance of the light-curing units, there was similarity in tensile strength with 20-s and 40-s exposure times and higher tensile strength when a 60-s light-activation time was used. Regarding microhardness, the halogen lamp had higher results when compared to the LED units. For all light-curing units, the variation of light-exposure time did not affect composite microhardness. However, lower irradiances needed longer light-activation times to produce similar effect as that obtained with high-irradiance light-curing sources.

Effect of a post-polymerization treatments on the flexural strength and vickers hardness of reline and acrylic denture base resins

This study evaluated the effect of water-bath and microwave post-polymerization treatments on the flexural strength and Vickers hardness of four autopolymerizing reline resins (Duraliner II-D, Kooliner-K, Tokuso Rebase Fast-TR and Ufi Gel Hard C-UGH) and one heat-polymerized acrylic resin (Lucitone 550-L), processed using two polymerization cycles (short cycle - 90 minutes at 73°C and 100°C for 30 minutes; and long cycle - 9 hours at 71°C). For each material, thirty specimens (64 x 10 x 3.3 mm) were made and divided into 3 groups (n=10). Specimens were tested after: processing (control group); water-bath at 55°C for 10 minutes (reline materials) or 60 minutes (L); and microwave irradiation. Flexural strength tests were performed at a crosshead speed of 5 mm/min using a three-point bending device with a span of 50 mm. The flexural strengths values were calculated in MPa. One fragment of each specimen was submitted to Vickers hardness test. Data were analyzed by 2-way ANOVA followed by Tukey's HSD test (α=0.05). L microwaved specimens (short cycle) exhibited significantly higher flexural strength means than its respective control group (p<0.05). Water-bath promoted a significant increase (p<0.05) in flexural strength of K and L (long cycle). The hardness of the tested materials was not influenced by the post-polymerization treatments. Post-polymerization treatments could be used to improve the flexural strength of some materials tested.