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Cavity Walls (cavity + wall)
Selected AbstractsIn vitro study of caries detection through sound dentin using a laser fluorescence device, DIAGNOdentEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2003Yukiteru Iwami The objective of this study was to investigate the feasibility of proximal surface caries detection using a laser fluorescence device, DIAGNOdent, through the sound dentin surrounding the cavity wall after removal of occlusal caries. Extracted sound human molars were ground to prepare horizontal and vertical dentin plates 1.4 mm thick. Extracted carious human molars were reduced in thickness horizontally from the occlusal surfaces until exposure of the dentin caries. The dentin plate was placed on the carious tooth. Before and after gradual thinning of the dentin plate from approximately 1.4 mm to 0.2 mm thick, the dentin caries was measured 10 times through the plate by the laser fluorescence device with a cone-shaped tip or a broad tip. When the dentin plate was reduced to less than 0.3 mm thick (using a combination of a horizontal plate and cone-shaped tip) or 0.2 mm thick (using the other combinations), the values measured with the laser fluorescence device were significantly larger than the values before reducing the thickness of the dentin. Based on these results, the device offers potential use as one of the screening tests for proximal surface caries detection through sound dentin when the sound dentin between tip and caries is thin. [source] Analysis of undrained cavity expansion in elasto-plastic soils with non-linear elasticityINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 1 2002Lai Fa Cao Abstract A large strain analysis of undrained expansion of a spherical/cylindrical cavity in a soil modelled as non-linear elastic modified Cam clay material is presented. The stress,strain response of the soil is assumed to obey non-linear elasticity until yielding. A power-law characteristic or a hyperbolic stress,strain curve is used to describe the gradual reduction of soil stiffness with shear strain. It is assumed that, after yielding, the elasto-plastic behaviour of the soil can be described by the modified Cam clay model. Based on a closed-form stress,strain response in undrained condition, a numerical solution is obtained with the aid of simple numerical integration technique. The results show that the stresses and the pore pressure in the soil around an expanded cavity are significantly affected by the non-linear elasticity, especially if the soil is overconsolidated. The difference between large strain and small strain solutions in the elastic zone is not significant. The stresses and the pore pressure at the cavity wall can be expressed as an approximate closed-form solution. Copyright © 2001 John Wiley & Sons, Ltd. [source] Calcium-phosphate surface coating by casting to improve bioactivity of titaniumJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 5 2001Taiji Sohmura Abstract In order to improve the bioactivity of titanium, an original surface treatment was attempted with the use of a casting technique was attempted. Pure titanium was cast into a special graphite mold in which the cavity wall was coated with hydroxyapatite (HA) powder. According to analyses of X-ray diffraction and EDX, the existence of HA and CaO and uptake of Ca and P on the surface of the titanium castings were identified. By immersing the specimen in Hank's solution, the concentrations of Ca and P on the surface increased with immersion time, and the formation of a thin layer with characteristics of spherical HA precipitates was observed after 1 week. The concentrations of Ca and P elements and the Ca/P ratio on the HA layer increased with immersion time. The formation of the HA layer on the titanium cast by this treatment was significantly accelerated compared with pure titanium. The present surface treatment of Ti is expected to improve early bone fixation of Ti implants. © 2001 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 58: 478,485, 2001 [source] Anti-adhesive Membrane for Pleural CavityARTIFICIAL ORGANS, Issue 3 2010Yasuharu Noishiki Abstract An anti-adhesive membrane containing a large amount of glycerin was developed for lung surgery and was tested in the pleural cavity of six dogs. The test membranes were put between the lung and the chest wound of the pleural cavity wall to separate them. In five of the animals, no adhesion was observed after 3 weeks in the area where the membrane had been inserted, but the area without the membrane showed firm adhesion between the lung and the pleural cavity wall. A sixth animal observed for 3 months also showed no adhesion. Seprafilm, which is the product of choice for peritoneal surgeries, was used as a control in six dogs. Seprafilm could not prevent adhesion in the pleural cavity of all six animals after 3 weeks observation. The new test membrane contained glycerin, which gathered and dispersed abundant water. Together with this, growth factors are also dispersed, resulting in dilution of excessive growth factors at the wound sites. In general, fibroblasts do not migrate in an extremely hydrous gel matrix. Migration of fibroblasts into the membrane is minimized, resulting in the prevention of formation of adhesion tissue composed of fibroblasts and collagen fibers. From the results, we assume that water can prevent adhesion after surgery. [source] Web based laboratory in electromagnetic compatibility using a Java appletCOMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 4 2006S. K. Goudos Abstract A web based virtual laboratory in electromagnetic compatibility using a Java applet is presented. The Java applet makes use of Green's functions calculations inside a rectangular cavity. The induced electric fields and surface currents on cavity walls are calculated and visualized in a user-friendly manner. Various source configurations are examined. A number of laboratory exercises using the applet is given. © 2006 Wiley Periodicals, Inc. Comput Appl Eng Educ 14: 269,280, 2006; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20087 [source] Full scale experiments for evaluating theoretical fire wall modelsFIRE AND MATERIALS, Issue 6 2004P. Clancy Abstract The aim of the research described in this paper was to provide experimental results for the evaluation of theoretical models for predicting the behaviour and time-to-failure of loadbearing and non-loadbearing wood framed walls in fire. References for thermal and mechanical properties of wood and gypsum board are given to provide comprehensive input for the evaluation of theoretical wall models. The scope of the research involved full-scale uninsulated cavity walls with well-controlled clearly known conditions including initial ambient vertical load capacity for benchmarking the reduction in capacity and stiffness, rotational stiffness of supports, eccentricity of vertical load, elastic moduli of wood and gypsum board in compression, stiffness of slip between gypsum board and studs and end stud effects. The experiments were repeated and they demonstrated that the controls led to high consistency in the results despite the inherent large variability of the mechanical properties of wood. The results include temperature distributions, initial vertical load capacity, load-deflection plots and times-to-failure. The results show that the temperatures in the studs are approximately uniform until all the moisture is vaporized. Thermal properties of wood will not vary significantly for consistent density, moisture content and species of wood. The main structural actions that should be modelled for different loading regimes are deduced. Copyright © 2004 John Wiley & Sons, Ltd. [source] Advances in modelling heat transfer through wood framed walls in fireFIRE AND MATERIALS, Issue 6 2001P. Clancy Described in this paper are advances made in modelling heat transfer through wood framed walls in fire. Previously unpublished experimental results are also given. This type of modelling is used for the determination of the performance of fire safety systems, such as wood framed wall barriers, in accordance with new performance-based building regulations being introduced around the world. Advances include a discrete modelling method for radiative heat transfer in cavities with re-entrant corners and gaps formed by the shrinkage of stud cross-sections. It has been shown that the formation of the gaps can prevent temperatures rising in the fire side of studs by as much as 100,200°C. A simple means of modelling heat transfer by the movement of moisture and vapour, involving the modification of conductivity values has been developed. Sloughing of gypsum board sheets has been satisfactorily modelled assuming that a sheet sloughs when the temperature on the surface opposite the fire reaches the melting point of glass fibres in the gypsum board; that is, approximately 700°C. Recommendations on thermal properties obtained independently by other researchers are presented. Overall, the advances improve temperature predictions and broaden the range of walls that can be modelled including staggered stud walls as well as ordinary cavity walls. Copyright © 2002 John Wiley & Sons, Ltd. [source] Cavity preparation using a superpulsed 9.6-,m CO2 laser,a histological investigationLASERS IN SURGERY AND MEDICINE, Issue 5 2002R. Müllejans Abstract Background and Objectives The superpulsed 9.6-,m CO2 laser is an effective laser for ablating dental tissues and decay. This histological study compares laser class V preparations with conventional treatment to evaluate the resulting formation at the cavity walls. Study Design/Materials and Methods Four class V preparations (one made with a diamond drill and three with the CO2 laser (9.6 ,m, 60 microseconds pulse width, 40 mJ pulse energy, 100 Hz, integrated scanner system, water cooling) were performed on ten extracted teeth. The cavities were filled with a composite resin partly including enamel and dentine conditioning. Results After laser preparation, no cracks or signs of carbonisation were detected. The results were comparable to those attained with conventional treatment. Following cavity filling without prior conditioning, gaps were noted at the cavosurface indicating a lack of adhesion. Dentinal bonding decreased gap formation significantly. Conclusion The 9.6-,m CO2 laser is an effective tool for cavity preparation. Lasers Surg. Med. 30:331,336, 2002. © 2002 Wiley-Liss, Inc. [source] Impeller Behavior and Displacement of the VentrAssist Implantable Rotary Blood PumpARTIFICIAL ORGANS, Issue 3 2004Michael K.H. Chung Abstract:, The VentrAssist implantable rotary blood pump, intended for long-term ventricular assist, is under development and is currently being tested for its rotor-dynamic stability. The pump is of the centrifugal type and consists of a shaftless impeller, also acting as the rotor of the brushless DC motor. The impeller remains passively suspended in the pump cavity by hydrodynamic forces, resulting from the small clearances between the impeller outside surfaces and the pump cavity. In the older version of the pump tested, these small clearances range from approximately 50 µm to 230 µm; the displacement of the impeller relative to the pump cavity is unknown in use. This article presents two experiments: the first measured displacement of the impeller using eddy-current proximity sensors and laser proximity sensors. The second experiment used Hall-effect proximity sensors to measure the displacement of the impeller relative to the pump cavity. All transducers were calibrated prior to commencement of the experiments. Voltage output from the transducers was converted into impeller movement in five degrees of freedom (x, y, z, ,x, and ,y). The sixth degree of freedom, the rotation about the impeller axis (,z), was determined by the commutation performed by the motor controller. The impeller displacement was found to be within the acceptable range of 8 µm to 222 µm, avoiding blood damage and contact between the impeller and cavity walls. Thus the impeller was hydrodynamically suspended within the pump cavity and results were typical of centrifugal pump behavior. This research will be the basis for further investigation into the stiffness and damping coefficient of the pump's hydrodynamic bearing. [source] | |||||||||||||