Development and testing of anode-supported solid oxide fuel cells with slurry-coated electrolyte and cathode

A laboratory setup was designed and put into operation for the development of solid oxide fuel cells (SOFCs). The whole project consisted of the preparation of the component materials: anode, cathode and electrolyte, and the buildup of a hydrogen leaking-free sample chamber with platinum leads and current collectors for measuring the electrochemical properties of single SOFCs. Several anode-supported single SOFCs of the type (ZrO(2):Y(2)O(3)+NiO) thick anode/(ZrO(2):Y(2)O(3)) thin electrolyte/(La(0.65)Sr(0.35)MnO(3)+ZrO(2):Y(2)O(3)) thin cathode have been prepared and tested at 700 and 800 degrees C after in situ H(2) anode reduction. The main results show that the slurry-coating method resulted in single-cells with good reproducibility and reasonable performance, suggesting that this method can be considered for fabrication of SOFCs. (c) 2005 Elsevier B.V. All rights reserved.

Rift to post-rift evolution of a passive continental margin: the Ponta Grossa Arch, SE Brazil

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

Morphology of Aortic Arch in Rabbits with Atherosclerosis Treated with Resveratrol

Objective: Atherosclerosis is a chronic inflammatory condition associated with the production of oxidative species. The phenoliccompound, resveratrol, seems to have cardioprotective activities preventing the oxidation of low-density lipoproteins.In this study we investigated the effect of resveratrol on prevention of induced atheromatosis, through the morphological study of the segment of aortic arch in White New Zealand rabbits.Study design: 20 rabbits were divided into four groups which received the following diet for 60 days: control group (CT) normal ration; resveratrol group (R) normal ration and resveratrol (3 mg/kg/day); cholesterol group (CL) 1.5% of cholesterol added to the ration; group cholesterol plus resveratrol (CR) 1.5% of cholesterol added to the ration and resveratrol (3 mg/kg/day). The analysis of the atherosclerotic lesions were performed by the means of appropriate histological techniques.Results and conclusions: The animals belonging to group CL showed atherosclerotic lesions with tunica intima thickening due to the presence of foam cells, placed in several disorganized layers, and extracellular lipid droplets in subendothelial conjunctive tissue.We also observed the invasion of foam cells in the beginning of tunica media. In animals belonging to group CR there were changes in the subendothelial of tunica intima, although in a minor degree of development as for the number of foam cells layers and extracellular lipid droplets. An invasion of foam cells in tunica media was observed in this group. We haven't seen any changes in tunica adventitia in any of the studied groups. There were not evident histological changes in any of the analised tunicas for groups CT and RConclusions: This study may help demonstrate that the phenolic compound, resveratrol, works as a preventive agent in the development of atherosclerotic lesions.

Loss of space and dental arch length after the loss of the lower first primary molar: A longitudinal study

The premature loss of primary teeth may harm the normal occlusal development, although there are debates relating to the necessity of using space maintainer appliances. The aim of the study is to evaluate the changes in the dental arch perimeter and the space reduction after the premature loss of the lower first primary molar in the mixed dentition stage. The sample consists of 4 lower arch plaster models of 31 patients, within the period of pre-extraction, 6, 12 and 18 months after the lower first primary molar extraction. A reduction of space was noted with the cuspid dislocation and the permanent incisors moving toward the space of the extraction site. It was concluded that the lower first molar primary premature loss, during the mixed dentition, implicates an immediate placement of a space maintainer.

Pressure field in the cathode-anode region of a high-power klystron amplifier

The pressure field of a high-power klystron amplifier in the cathode and anode region was investigated. The investigation was performed using a 1.3 GHz, 100 A and 240 kV high-power klystron with five reentrant coaxial cavities, assembled in cylindrical drift tube 1.2 m long. The diffusion equation in mathematical model was also solved by using a 3-D finite element method code, in order to obtain pressure profile in region of interest. The results show that density profile of molecules between cathode-anode region was determined, where cathode pressure is approximately 10% higher than anode pressure.

Setting the preheating process of electronic ballasts for hot-cathode fluorescent lamps, considering the Rh/Rc ratio

This paper presents a new model for the representation of the electrodes filaments of fluorescent lamps, during their preheating, and an analysis capable to guide the design of the preheating process in electronic ballasts. The main improvement obtained with the lamp model is the accurate theoretical reproduction of the behavior of the Rh/Rc ratio during the preheating process. In addition, using the proposed methodology based on the lamp model, it is possible to set a proper preheating process to the electrodes filaments, without the necessity of exhaustive empirical adjustments in the prototype, reducing time and costs involved in the design of ballasts with preheating capabilities. © 2006 IEEE.

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.

Comparative Analysis of 2 Techniques of Double-Gloving Protection During Arch Bar Placement for Intermaxillary Fixation

Purpose: This study was conducted to comparatively evaluate, in a prospective and randomized manner, 2 techniques for providing double-gloving protection during arch bar placement for intermaxillary fixation. Materials and Methods: A total of 42 consecutive patients in whom application of an Erich bar was indicated for intermaxillary fixation were equally divided into 2 groups. In group 1, 2 sterile surgical gloves were used; in group 2, a nonsterile disposable inner glove was used under a sterile surgical glove. Wilcoxon, Mann-Whitney, Kruskal-Wallis, and binomial statistical tests were used to analyze the findings. Results: A total of 103 perforations were found in the outer gloves (47 in group 1 and 56 in group 2), along with 5 perforations in inner gloves in both groups (α = .01). No significant statistical difference was found between groups in terms of inner glove perforations (α = .05). The nondominant hand presented with 70.9% of the perforations, statistically significant to 1%. Conclusions: Both double-gloving techniques were found to provide effective clinician protection. The use of a nonsterile disposable glove under the surgical glove is possible for less-invasive procedures, offering the same safety as using 2 sterile surgical gloves while decreasing operational costs. This method does not eliminate the need to change gloves when a perforation is suspected or noted during the surgery, however. © 2007 American Association of Oral and Maxillofacial Surgeons.

Performance of the CMS cathode strip chambers with cosmic rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47μm to 243μm. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns. © 2010 IOP Publishing Ltd and SISSA.

Comparison of different designs of implant-retained overdentures and fixed full-arch implant-supported prosthesis on stress distribution in edentulous mandible - A computed tomography-based three-dimensional finite element analysis

A finite element analysis was used to compare the effect of different designs of implant-retained overdentures and fixed full-arch implant-supported prosthesis on stress distribution in edentulous mandible. Four models of an human mandible were constructed. In the OR (O'ring) group, the mandible was restored with an overdenture retained by four unsplinted implants with O'ring attachment; in the BC (bar-clip) -C and BC groups, the mandibles were restored with overdentures retained by four splinted implants with bar-clip anchor associated or not with two distally placed cantilevers, respectively; in the FD (fixed denture) group, the mandible was restored with a fixed full-arch four-implant-supported prosthesis. Models were supported by the masticatory muscles and temporomandibular joints. A 100-N oblique load was applied on the left first molar. Von Mises (σvM), maximum (σmax) and minimum (σmin) principal stresses (in MPa) analyses were obtained. BC-C group exhibited the highest stress values (σvM=398.8, σmax=580.5 and σmin=-455.2) while FD group showed the lowest one (σvM=128.9, σmax=185.9 and σmin=-172.1). Within overdenture groups, the use of unsplinted implants reduced the stress level in the implant/prosthetic components (59.4% for σvM, 66.2% for σmax and 57.7% for σmin versus BC-C group) and supporting tissues (maximum stress reduction of 72% and 79.5% for σmax, and 15.7% and 85.7% for σmin on the cortical and trabecular bones, respectively). Cortical bone exhibited greater stress concentration than the trabecular bone for all groups. The use of fixed implant dentures and removable dentures retained by unsplinted implants to rehabilitate edentulous mandible reduced the stresses in the periimplant bone tissue, mucosa and implant/prosthetic components. © 2013 Elsevier Ltd.

Rehabilitation of the Maxillary Arch After Bone Graft Using Immediate Loading With Implant-Supported Fixed Restoration

Moderate and controlled loading environments support or enhance osteogenesis, and, consequently, a high degree of bone-to-implant contact can be acquired. This is because when osteoprogenitor cells are exposed to limited physical deformation, their differentiation into osteoblasts is enhanced. Then, some range of microstrain is considered advantageous for bone ingrowth and osseointegration. The primary stability has been considered one of the main clinical means of controlling micromotion between the implant and the forming interfacial tissue, which helps to establish the proper mechanical environment for osteogenesis. Based on the biological aspects of immediate loading (IL), the objective of this study is to present a clinical case of maxillary arch rehabilitation using immediate loading with implant-supported fixed restoration after bone graft. Ten dental implants were placed in the maxilla 6 months after the autogenous bone graft, removed from the mandible (bilateral oblique line and chin), followed by the installation of an immediate-load fixed cross-arch implant-supported restoration because primary stability was reached for 8 implants. In addition, instructions about masticatory function and how it is related to interfacial micromotion were addressed and emphasized to the patient. The reasons for the IL were further avoidance of an interim healing phase, a potential reduction in the number of clinical interventions for the patient, and aesthetic reasons. After monitoring the rehabilitation for 8 years, the authors can conclude that maxillary IL can be performed followed by a well-established treatment planning based on computed tomography, providing immediate esthetics and function to the patient even when autogenous bone graft was previously performed in the maxilla.

The influence of bone quality on the biomechanical behavior of full-arch implant-supported fixed prostheses

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

The role of superstructure material on the stress distribution in mandibular full-arch implant-supported fixed dentures. A CT-based 3D-FEA

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

Non-linear 3D finite element analysis of full-arch implant-supported fixed dentures

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