Search results for "Ultima"
showing 10 items of 396 documents
In vitro assessment of retention and resistance failure loads of complete coverage restorations made for anterior maxillary teeth restored with two d…
2019
Background The purpose of this in vitrostudy was to evaluate the retention and resistance form of complete coverage restorations supported by two different cast post and core designs. Material and methods Forty extracted maxillary central incisors were randomly divided into four groups of 10 specimens each (namely A, B, C and D). All specimens were endodontically treated and a uniform post space of 9mm was created. All prepared teeth had a 360o chamfer ferrule of 2mm in axial height measured 0.5mm coronally from the cementoenamel junction (CEJ) and an axial wall thickness of 1.5 mm. Specimens in groups A and C received cast post and cores with the standardized core design, where the core en…
In vitro investigation of the impact of remaining tooth structure on the tensile failure loads of overdenture copings
2019
Background The purpose of this in vitro study was to evaluate the impact of the remaining tooth structure on the retention of overdenture cast metal copings. Material and Methods A freshly extracted intact mandibular human canine (length 25 mm) was selected and endodontically treated. An incisal reduction of 4 mm with no ferrule preparation was performed and a post space of 12 mm was created. By using polyvinyl siloxane duplication material and autopolymerizing polymethylmethacrylate resin, ten resin teeth analogs (control group) were obtained. A second set of ten resin teeth analogs (group 1) was created by preparing on the original natural tooth a 360o ferrule design of 1 mm in height and…
Kairos, the decisive moment
2015
En este artículo haremos un recorrido conceptual por el término y las problemáticas de la fotografía, utilizando la figura de Cartier-Bresson como hilo conductor. Tras intentar determinar las características que la definen, analizaremos la relación de la misma con la pintura; trataremos de ver, a continuación, diferentes opiniones y posturas acerca de si puede o no considerarse arte; y apuntaremos, en última instancia, ciertos cambios en el concepto de belleza que ha conllevado esta nueva forma de reproducir el mundo. : In this article we will explore the concept and problems of photography, using the figure of Cartier-Bresson as the thread that runs through the entire essay. After trying t…
Halloysite nanotubes as sustainable nanofiller for paper consolidation and protection
2014
We investigated the filling process of cellulose-based paper with natural clay nanotubes and their mixtures with hydroxypropyl cellulose (HPC) that is commonly used as glue and consolidant for degraded paper. A comprehensive characterization of the materials was carried out through morphology, wettability, thermal degradation, and tensile properties. The treatment with halloysite nanotubes generated a decrease of the paper mechanical performance and did not alter the thermal properties. The co-presence of HPC and nanoparticles generated a more uniform nanotubes distribution in the paper fibrous structure and a significant enhancement of both the mechanical properties and the surface hydroph…
Reheating the Standard Model from a hidden sector
2016
We consider a scenario where the inflaton decays to a hidden sector thermally decoupled from the visible Standard Model sector. A tiny portal coupling between the hidden and the visible sectors later heats the visible sector so that the Standard Model degrees of freedom come to dominate the energy density of the Universe before Big Bang Nucleosynthesis. We find that this scenario is viable, although obtaining the correct dark matter abundance and retaining successful Big Bang Nucleosynthesis is not obvious. We also show that the isocurvature perturbations constituted by a primordial Higgs condensate are not problematic for the viability of the scenario.
Water-Dependent Blending of Pectin Films: The Mechanics of Conjoined Biopolymers
2020
Biodegradable pectin polymers have been recommended for a variety of biomedical applications, ranging from the delivery of oral drugs to the repair of injured visceral organs. A promising approach to regulate pectin biostability is the blending of pectin films. To investigate the development of conjoined films, we examined the physical properties of high-methoxyl pectin polymer-polymer (homopolymer) interactions at the adhesive interface. Pectin polymers were tested in glass phase (10&ndash
Effect of Morphology and Size of Halloysite Nanotubes on Functional Pectin Bionanocomposites for Food Packaging Applications
2017
Pectin bionanocomposite films filled with various concentrations of two different types of halloysite nanotubes were prepared and characterized in this study as potential films for food packaging applications. The two types of halloysite nanotubes were long and thin (patch) (200-30 000 nm length) and short and stubby (Matauri Bay) (50-3000 nm length) with different morphological, physical, and dispersibility properties. Both matrix (pectin) and reinforcer (halloysite nanotubes) used in this study are considered as biocompatible, natural, and low-cost materials. Various characterization tests including Fourier transform infrared spectroscopy, field emission scanning electron microscopy, rele…
Limit order placement as an utility maximization problem and the origin of power law distribution of limit order prices
2006
I consider the problem of the optimal limit order price of a financial asset in the framework of the maximization of the utility function of the investor. The analytical solution of the problem gives insight on the origin of the recently empirically observed power law distribution of limit order prices. In the framework of the model, the most likely proximate cause of this power law is a power law heterogeneity of traders' investment time horizons .
In-process tool force and rotation variation to control sheet thickness change in friction stir welding of magnesium alloys
2016
Two different in-process control strategies, developed in order to produce sound joints in AZ31 magnesium alloy by Friction Stir Welding on sheet blanks with a non-uniform thickness, are presented and compared. To this purpose, sheets with dip or hump were machined and welded by either changing the rotational speed or the tool plunging in order to keep constant the vertical force occurring during welding. The mechanical strength of the joints was measured in the zones where the sheets before welding were characterised by different thicknesses. The sheets welded by the two different strategies are characterized by very similar ultimate tensile strength values. Finally, the results showed tha…
Risk of failure for the salso river railroad steel bridge
2020
Abstract The degradation state of railroad steel bridges is one of the most important and difficult aspects to be interpreted. The use of steel bridges started from 1900, and they are still in service today as railroad bridges. The case study examined was that of a bridge railroad steel bridge having a total length of 112 m and constituted by three isostatic, reticular beams having a Pratt type composition. The substructures (two shoulders and two intermediate piles) are in masonry with a reinforced concrete beam in the upper portion. The structure (steel bridge and piers) is in a degraded state. To determine the degradation level, non-destructive and partially destructive tests were carrie…