Search results for "medium"
showing 10 items of 3746 documents
PLZT laser beam modulator
1992
Abstract Laser beam modulator on transparent electrooptic PLZT ceramics are developed for the use in teaching process in schools and universities. Characteristics of the modulator and its electronic control unit are given.
Metal oxide semiconductor sensors for monitoring of oxidative status evolution and sensory analysis of virgin olive oils with different phenolic cont…
2009
An electronic nose based on an array of six metal oxide semiconductor sensors was used to monitor the oxidative status of virgin olive oils (VOO) during storage. VOO samples, with and without phenolic compounds, were stored at 60 °C for 7 weeks. Once a week, absorbance at 232 and 270 nm, oxidized stability index, electronic nose, and sensory analysis were evaluated. Linear discriminant analysis models were constructed in order to classify samples according to oxidative levels. Based on these models, VOO samples with and without phenolic compounds at different storage times, divided in eight categories, were correctly classified also achieving a good correlation for sensory analysis. The met…
Hydrothermal aging of carbon reinforced epoxy laminates with nanofibrous mats as toughening interlayers
2016
Electrospun mats have been applied as toughening interlayers in high performance carbon fiber epoxy composites. While the toughening mechanism exerted by the mat at the interface is the subject of several recent studies, no investigations are reported on the aging behaviour of laminates comprising these nanostructured elements. This work investigates the influence of the combined effect of water and temperature (90 °C) on laminates with Nylon 6,6 electrospun membranes placed either at the middle plane only or at each interlayer. The water-uptake behaviour is modelled by a two-stage diffusion model and compared with the behaviour of the neat resin and of the laminate without mats. Interestin…
Characterization of Sorolla's gouache pigments by means of spectroscopic techniques
2016
Abstract This paper presents the characterization of the Joaquin Sorolla's gouache sketches for the oil on canvas series “Vision of Spain” commissioned by A. M. Huntington to decorate the library of the Hispanic Society of America in New York. The analyses were focused on the identification of the elemental composition of the gouache pigments by means of portable EDXRF spectrometry in a non-destructive mode. Additionally, SEM-EDX and FTIR analyses of a selected set of micro-samples were carried out to identify completely the pigments, the paint technique and the binding media. The obtained results have confirmed the identification of lead and zinc white, vermillion, earth pigments, ochre, z…
SMEs' Growth Heterogeneity - Evidence from Regional Developments
2014
Previous empirical research on small and medium-sized enterprises (SMEs) frequently struggled with the extreme heterogeneity of these frms. We scrutinise one major source of this heterogeneity: SMEs' growth development. Based on a large dataset of French, Italian, UK and US firms between 2000 and 2008, we find that SMEs fall in two categories in all countries: One large group of firms that display only slow growth and one much smaller group that actively seek strong growth. We show that the growth factors particularly of the slowly-growing firms vary strongly between the countries. European SMEs differ mainly in the growth effects of their ownership structures. US firms set themselves apart…
Evaluating European Union support for innovation in Spanish small and medium enterprises
2009
Finding funding is one of the main problems small and medium enterprises (SMEs) face, which is why the European Union has set up programmes to support SME development. This paper has two objectives: firstly, to describe the different European funding programmes available to Spanish firms; secondly, to present an empirical study on the use Spanish SMEs (and especially, SMEs in the service sector) make of these programmes in order to innovate, together with an analysis of the importance these funding programmes have on SME innovation.
Product development process in Spanish SMEs: an empirical research
2002
Rapid product development has been treated as a competitive strategy in a global market environment. It is essential to improve the product development process with the objective of reducing product development cycle time and hence to reach the market as quickly as possible. Large-scale companies have adopted new strategies and technologies to reduce the product development cycle time, taking into account various market and innovation barriers. However, small and medium enterprises (SMEs) have not received adequate attention from researchers for their product development process. In this paper, an attempt has been made to analyze the critical success factors for the product development proc…
Resistance to demineralisation of adjacent enamel and dentine, fluoride release and dentine bond strength of fluoride-containing self-etch adhesive s…
2019
Background The current study aimed to assess the amount of fluoride released from fluoride-containing dental adhesives and its effect on micro-tensile bond strength (µTBS) and on resistance to demineralisation of dentine and enamel. Material and Methods Two fluoride-containing dental adhesives, and a fluoride-free adhesive were used as experimental adhesives. After thermal cycling the µ-TBS of adhesives to dentine and the failure mode were assessed. The fluoride release and cross-sectional microhardness (CSMH) of specimens were measured before and after one day, 7 and 28 days of pH-cycling. The data were analysed using one-way ANOVA, Weibull statistics and repeated measures ANOVA. Results T…
Effects of acids used in the microabrasion technique: microhardness and confocal microscopy analysis
2015
Background: This study evaluated the effects of the acids used in the microabrasion on enamel. Material and Methods: Seventy enamel/dentine blocks (25 mm 2 ) of bovine incisors were divided into 7 groups (n=10). Experimental groups were treated by active/passive application of 35% H 3 PO 4 (E1/E2) or 6.6% HCl (E3/ E4). Control groups were treated by microabrasion with H 3 PO 4 +pumice (C5), HCl+silica (C6), or no treatment (C7). The superficial (SMH) and cross-sectional (CSMH; depths of 10, 25, 50, and 75 μm) microhardness of enamel were analyzed. Morphology was evaluated by confocal laser-scanning microscopy (CLSM). Data were analyzed by analysis of variance (Proc Mixed), Tukey, and Dunnet…
Influence of energy drinks on enamel erosion : in vitro study using different assessment techniques
2021
Background Dental erosion has become a relevant public health problem in recent years and is related to the increase in the consumption of acidic beverages. Objective: The aim of the present study was to evaluate the erosive potential of energy drinks on dental enamel using an in vitro erosion model. Material and Methods Thirty-eight blocks of human enamel were divided into four groups: G1- TNT Energy Drink®(n=8), G2- Red Bull® (n=10), G3- Monster Energy® (n=10), and G4- Coca-Cola® (n=10) (positive control). For the chemical analysis, the pH values, titratable acidity, and buffering capacity of the beverages were measured in triplicate. For the erosive test, the specimens were immersed in t…