Metal surface and subsurface inspection using nondestructive optical methods

This thesis considers nondestructive optical methods for metal surface and subsurface inspection. The main purpose of this thesis was to study some optical methods in order to find out their applicability to industrial measurements. In laboratory testing the simplest light scattering approach, measurement of specular reflectance, was used for surface roughness evaluation. Surface roughness, curvature and finishing process of metal sheets were determined by specular reflectance measurements. Using a fixed angleof incidence, the specular reflectance method might be automated for industrialinspection. For defect detection holographic interferometry and thermography were compared. Using either holographic interferometry or thermography, relativelysmall-size defects in metal plates could be revealed. Holographic techniques have some limitations for industrial measurements. On the contrary, thermography has excellent prospects for on-line inspection, especially with scanning techniques.

Focal Osteoporotic Bone Marrow Defect Mimicking A Mandibular Cystic Lesion.

An unusual presentation of a focal osteoporotic bone marrow defect (FOBMD) of the mandible mimicking a cystic lesion is documented. A definitive diagnosis could be established only on the basis of the histopathologic evaluation. A 66-year-old Brazilian woman was referred by her dentist for well-defined radiolucency of the mandibular molar region suggesting a cystic lesion of odontogenic origin. The computed tomography scan confirmed that the lesion did not affect the corticals. The biopsy confirmed the diagnosis of FOBMD. The diagnostic difficulty in the current case is obvious, because FOBMD, usually exhibiting an ill-defined radiolucency, is seldom suspected preoperatively when a differential diagnosis is considered for focal well-defined radiolucent areas in the jaws.

Surface and subsurface erosion of primary enamel by acid beverages over time

This study evaluated the influence of a cola-type soft drink and a soy-based orange juice on the surface and subsurface erosion of primary enamel, as a function of the exposure time. Seventy-five primary incisors were divided for microhardness test (n=45) or scanning electron microscopy (SEM) analysis (n=30). The specimens were randomly assigned to 3 groups: 1 - artificial saliva (control); 2 - cola-type soft drink; and 3 - soy-based orange juice. Immersion cycles in the beverages were undertaken under agitation for 5 min, 3 times a day, during 60 days. Surface microhardness was measured at 7, 15, 30, 45 and 60 days. After 60 days, specimens were bisected and subsurface microhardness was measured at 30, 60, 90, 120, 150 and 200 µm from the surface exposed. Data were analyzed by ANOVA and Tukey’s test (a=0.05). Groups 2 and 3 presented similar decrease of surface microhardness. Regarding subsurface microhardness, group 2 presented the lowest values. SEM images revealed that after 60 days the surfaces clearly exhibited structural loss, unlike those immersed in artificial saliva. It may be concluded that erosion of the surfaces exposed to the cola-type soft drink was more accentuated and directly proportional to the exposure time.

Alveolar osseous defect in rat for cell therapy: preliminary report

PURPOSE: To study were to reproduce an alveolar bone defect model in Wistar rats to be used for testing the efficacy of stem cell therapies. Additionally, we also aimed to determine the osteogenesis process of this osseous defect in the 1 month period post-surgery. METHODS: The animals were randomly divided into two groups of 7 animals each. A gingivobuccal incision was made, and a bone defect of 28 mm² of area was performed in the alveolar region. Animals were killed at 2 weeks after surgery (n=7) and 4 weeks after surgery (n=7). RESULTS: The average area of the alveolar defect at time point of 2 weeks was 22.27 ± 1.31 mm² and the average area of alveolar defect at time point of 4 weeks was 9.03 ± 1.17 mm². The average amount of bone formation at time point of 2 weeks was 5.73 ± 1.31 mm² and the average amount of bone formation at time point of 4 weeks was 19 ± 1.17 mm². Statistically significant differences between the amount of bone formation at 2 weeks and 4 weeks after surgery were seen (p=0.003). CONCLUSION: The highest rate of ossification occurred mostly from 2 to 4 weeks after surgery. This observation suggests that 4 weeks after the bone defect creation should be a satisfactory timing to assess the potential of bone inductive stem cells to accelerate bone regeneration in Wistar rats.

Horizontal subsurface flow constructed wetlands for mitigation of ametryn-contaminated water

The feasibility of using constructed wetlands (CWs) for the mitigation of pesticide runoff has been studied in the last decade. However, a lack of related data was verified when subsurface flow constructed wetlands (SSF CWs) are considered for this purpose. In the present work, SSF CWs were submitted to continuous ametryn addition and evaluated during an I I-week period, with the aim of determining the feasibility of these systems for mitigation of contaminated water. Ametryn was not added to one CW cell in order to provide a control for the experiments. Monitoring of treatment performance was executed by standard water quality parameters, ametryn chromatography quantification and macrophyte (Typha latifolia L) nutritional and agronomic property analysis. Results indicated that 39% of the total initially added amount of ametryn was removed, transferred or transformed. Herbicide metabolism and mineralisation were carried out by chemical and biological mechanisms. No statistic differences were observed in nutritional contents found in the T. latifolia crops of the CWs after the experimental period. Moreover, the biomass production (one valuable source of renewable energy) was equal to 3.3 t.ha(-1) (dry matter) in wetland cells. It was concluded that constructed wetland systems are capable of mitigating water contaminated with ametryn, acting as buffer filters between the emission sources and the downstream superficial water bodies.

Application of Low-Level Laser Irradiation (LLLI) and rhBMP-2 in Critical Bone Defect of Ovariectomized Rats: Histomorphometric Evaluation

Objectives: The aim of this study was to evaluate the osteogenic potential of recombinant human bone morphogenetic protein-2 (rhBMP-2) and low-level laser irradiation (LLLI), isolated or combined in critical bone defects (5mm) in parietal bone using ovariectomized female rats as an experimental animal model. Materials and Methods: Forty-nine female Wistar rats, bilaterally ovariectomized (OVX), were divided into seven treatment groups of seven animals each: (I) laser in a single application, (II) 7 mu g of pure rhBMP-2, (III) laser and 7 mu g of pure rhBMP-2, (IV) 7 mu g of rhBMP-2/monoolein gel, (V) laser and 7 mu g of rhBMP-2/monoolein gel, (VI) laser and pure monoolein gel, and (VII) critical bone defect controls. The low-level laser source used was a gallium aluminum arsenide semiconductor diode laser device (lambda = 780 nm, D = 120 J/cm(2)). Results: Groups II and III presented higher levels of newly formed bone than all other groups with levels of 40.57% and 40.39%, respectively (p < 0.05). The levels of newly formed bone of groups I, IV, V, and VI were similar with levels of 29.67%, 25.75%, 27.75%, and 30.64%, respectively (p > 0.05). The area of new bone formation in group VII was 20.96%, which is significantly lower than groups I, II, III, and VI. Conclusions: It was concluded that pure rhBMP-2 and a single dose of laser application stimulated new bone formation, but the new bone formation area was significantly increased when only rhBMP-2 was used. Additionally, the laser application in combination with other treatments did not influence the bone formation area.

Defect-induced effects on carrier migration through one-dimensional poly(para-phenylenevinylene) chains

Defects in one-dimensional (1D) systems can be intrinsically distinct from its three-dimensional counterparts, and polymer films are good candidates for showing both extremes that are difficult to individuate in the experimental data. We study theoretically the impact of simple hydrogen and oxygen defects on the electron transport properties of one-dimensional poly(para-phenylenevinylene) chains through a multiscale technique, starting from classical structural simulations for crystalline films to extensive ab initio calculations within density functional theory for the defects in single crystalline-constrained chains. The most disruptive effect on carrier transport comes from conjugation breaking imposed by the overcoordination of a carbon atom in the vinyl group independently from the chemical nature of the defect. The particular case of the [C=O] (keto-defect) shows in addition unexpected electron-hole separation, suggesting that the experimentally detected photoluminescence bleaching and photoconductivity enhancement could be due to exciton dissociation caused by the 1D characteristics of the defect.

Mechanism of point-defect diffusion in a two-dimensional colloidal crystal

The dynamics and mechanism of migration of a vacancy point defect in a two-dimensional (2D) colloidal crystal are studied using numerical simulations. We find that the migration of a vacancy is always realized by topology switching between its different configurations. From the temperature dependence of the topology switch frequencies, we obtain the activation energies for possible topology transitions associated with the vacancy diffusion in the 2D crystal. (C) 2011 American Institute of Physics. [doi:10.1063/1.3615287]

Woodgrain defect on tinned steel Flandres foil

Tin electrocoated steel strip, also referred to as Flandres foil, is largely used for manufacturing food containers. Tinplates must have good corrosion resistance, workability, weldability, as well as a bright appearance. The woodgrain defect, a not yet fully understood defect that occurs on tinplates and accounts for their high scrap rate, consists of alternate bands of bright/dull reflectivity and resembles longitudinally cut wood. Observations of the woodgrain defect by scanning electron microscopy showed that the molten tin spreads irregularly during both the melting and solidification stages. X-ray diffraction analyses showed that the metallic tin tended to crystallize in the (200) direction for coupons with and without the woodgrain defect. Nevertheless, the preferential orientation degree decreased for coupons with the woodgrain defect. The rocking curves, also known as omega-scan, showed that the tin grains were uniformly aligned parallel to the strip surface for coupons with no defects, whereas for tinplates with woodgrain, the tin grains were not uniformly oriented, probably due to the misalignment of the grains in relation to the surface. (C) 2011 Elsevier Inc. All rights reserved.

A study of plastic deformation around a defect using the magnetic Barkhausen noise in ASTM 36 steel

The present work presents the measurements of the magnetic Barkhausen noise (MBN) in ASTM 36 steel samples around a pit under plastic deformation. The contour maps obtained from these Barkhausen noise measurements are compared with the finite element analysis of the ideal plastic deformation. Also, a parameter of the Barkhausen signal to detect the plastic deformation around the pit in ASTM 36 steel is obtained. Additionally to that, we propose another MBN parameter to estimate the pit width using the Barkhausen noise. (c) 2007 Elsevier Ltd. All rights reserved.

A plateau detected in lead accumulation in subsurface deciduous enamel from individuals exposed to lead may be useful to identify children and regions exposed to higher levels of lead

In a previous study, we showed 4 times more lead in surface deciduous enamel (1.9-5.9 mu m) of a notoriously contaminated area (Bauru, Sao Paulo State, Brazil) in comparison to samples from a region with no lead contamination described (Ribeirao Preto, Sao Paulo State, Brazil). The samples from the more superficial enamel (1.9-3.18 mu m) showed higher amounts of lead and the highest variability, while in the subsurface enamel (3.18-5.9 mu m) a plateau in lead content was detected in children living in the contaminated environment (around 600 mu g/g). Here we expand our previous study, and use only samples obtained from subsurface enamel (Ribeirao Preto, n = 186; Bauru, n = 20). We tried to distinguish regions with more children with lead above the threshold of 600 mu g/g of lead in enamel. We tested whether differences in the percentage of children with ""high"" lead (>= 600 mu g/g) could be observed among the different Kindergartens studied in Ribeirao Preto. We also tested whether these results were different from the ones provided by conventional comparison of the data. Ribeirao Preto showed almost 4 times less lead than Bauru (p < 0.0001), and a statistically significant difference was found only in Ribeirao Preto between Kindergarten 2 and 5 (p<0.01). Twelve percent of the children from Ribeirao Preto had ""high"" lead, while 55% of the children from Bauru did so. However, when we looked at the percentages of children with ""high"" lead in each Kindergarten, and compared them, a whole new picture emerged, in which we could see children with ""high"" lead concentrated mainly in 3 Kindergartens from Ribeirao Preto, with Kindergarten 5 with 33% of the children with ""high"" lead, being statistically different from all Kindergartens, except 4 and 6. The threshold of 600 mu g/g of lead in subsurface enamel was tentatively settled here after the plateau seen in exposed children, and enabled us to identify locations with more children exposed to a higher amount of lead. (C) 2008 Elsevier Inc. All rights reserved.

Analysis of soil wetting and solute transport in subsurface trickle irrigation

The increased use of trickle or drip irrigation is seen as one way of helping to improve the sustainability of irrigation systems around the world. However, soil water and solute transport properties and soil profile characteristics are often not adequately incorporated in the design and management of trickle systems. In this paper, we describe results of a simulation study designed to highlight the impacts of soil properties on water and solute transport from buried trickle emitters. The analysis addresses the influence of soil hydraulic properties, soil layering, trickle discharge rate, irrigation frequency, and timing of nutrient application on wetting patterns and solute distribution. We show that (1) trickle irrigation can improve plant water availability in medium and low permeability fine-textured soils, providing that design and management are adapted to account for their soil hydraulic properties, (2) in highly permeable coarse-textured soils, water and nutrients move quickly downwards from the emitter, making it difficult to wet the near surface zone if emitters are buried too deep, and (3) changing the fertigation strategy for highly permeable coarse-textured soils to apply nutrients at the beginning of an irrigation cycle can maintain larger amounts of nutrient near to and above the emitter, thereby making them less susceptible to leaching losses. The results demonstrate the need to account for differences in soil hydraulic properties and solute transport when designing irrigation and fertigation management strategies. Failure to do this will result in inefficient systems and lost opportunities for reducing the negative environmental impacts of irrigation.

Persistence of ventilatory defect after resolution of pulmonary interstitial emphysema in a preterm baby

Pulmonary interstitial emphysema is a common complication of mechanical ventilation in preterm babies. We report a case of severe unilateral pulmonary interstitial emphysema in a premature newborn, treated with high-frequency oscillatory ventilation, lateral decubitus positioning and selective intubation. After complete radiological resolution of the pulmonary emphysema in the left lung, the patient was studied by electrical impedance tomography and a marked reduction of ventilation was identified in the left lung despite radiological resolution of the cysts. This finding indicates that functional abnormalities may persist for longer periods after radiologic resolution of such lesions.

Effects of Si content on defect band formation in hypoeutectic Al-Si die castings

Al-3-11% Si alloys have been high-pressure die-cast and characterized microstructurally. Alstruc was used to calculate the solidification characteristics and fraction of eutectic. Defect bands were observed at all Si contents, although their constitution, position and distinctiveness were a function of Si content. The defect bands contain a higher fraction Al-Si eutectic than the surroundings in all alloys, and porosity was additionally found in the band in AlSi3. With decreasing Si content, the defect bands formed closer to the casting surface, became more prevalent and also the width of the bands decreased. These differences are discussed by considering the effect of Si content on the distribution of solid in the mushy wall layers and on the feeding potentials of the alloys. The observations are consistent with the mechanism proposed by Gourlay et al. in which bands form due to deformation within the solidifying mushy wall layers. (c) 2005 Elsevier B.V. All rights reserved.

Hydraulic tracer studies in a pilot scale subsurface flow constructed wetland

Current design procedures for Subsurface Flow (SSF) Wetlands are based on the simplifying assumptions of plug flow and first order decay of pollutants. These design procedures do yield functional wetlands but result in over-design and inadequate descriptions of the pollutant removal mechanisms which occur within them. Even though these deficiencies are often noted, few authors have attempted to improve modelling of either flow or pollutant removal in such systems. Consequently the Oxley Creek Wetland, a pilot scale SSF wetland designed to enable rigorous monitoring, has recently been constructed in Brisbane, Australia. Tracer studies have been carried out in order to determine the hydraulics of this wetland prior to commissioning it with sealed sewage. The tracer studies will continue during the wetland's commissioning and operational phases. These studies will improve our understanding of the hydraulics of newly built SSF wetlands and the changes brought on by operational factors such as biological films and wetland plant root structures. Results to date indicate that the flow through the gravel beds is not uniform and cannot be adequately modelled by a single parameter, plug flow with dispersion, model. We have developed a multiparameter model, incorporating four plug flow reactors, which provides a better approximation of our experimental data. With further development this model will allow improvements to current SSF wetland design procedures and operational strategies, and will underpin investigations into the pollutant removal mechanisms at the Oxley Creek Wetland. (C) 1997 IAWQ. Published by Elsevier Science Ltd.