In vitro evaluation of a multispecies oral biofilm over antibacterial coated titanium surfaces

Peri-implantitis is an infectious disease that affects the supporting soft and hard tissues around dental implants and its prevalence is increasing considerably. The development of antibacterial strategies, such as titanium antibacterial-coated surfaces, may be a promising strategy to prevent the onset and progression of peri-implantitis. The aim of this study was to quantify the biofilm adhesion and bacterial cell viability over titanium disc with or without antibacterial surface treatment. Five bacterial strains were used to develop a multispecies oral biofilm. The selected species represent initial (Streptococcus oralis and Actinomyces viscosus), early (Veillonella parvula), secondary (Fusobacterium nucleatum) and late (Porphyromonas gingivalis) colonizers. Bacteria were sequentially inoculated over seven different types of titanium surfaces, combining different roughness level and antibacterial coatings: silver nanoparticles and TESPSA silanization. Biofilm formation, cellular viability and bacterial quantification over each surface were analyzed using scanning electron microscopy, confocal microscopy and real time PCR. Biofilm formation over titanium surfaces with different bacterial morphologies could be observed. TESPSA was able to significantly reduce the cellular viability when compared to all the surfaces (p?<?0.05). Silver deposition on titanium surface did not show improved results in terms of biofilm adhesion and cellular viability when compared to its corresponding non-coated surface. The total amount of bacterial biofilm did not significantly differ between groups (p?>?0.05). TESPSA was able to reduce biofilm adhesion and cellular viability. However, silver deposition on titanium surface seemed not to confer these antibacterial properties.

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An autonomous valve stiction detection system based on data characterization

This paper proposes a valve stiction detection system which selects valve stiction detection algorithms based on characterizations of the data. For this purpose, novel data feature indexes are proposed, which quantify the presence of oscillations, mean-nonstationarity, noise and nonlinearities in a given data sequence. The selection is then performed according to the conditions on the index values in which each method can be applied successfully. Finally, the stiction detection decision is given by combining the detection decisions made by the selected methods. The paper ends demonstrating the effectiveness of the proposed valve stiction detection system with benchmark industrial data.     

Total Oxidation of Methane Over Sulfur Poisoning Resistant Pt/ZrO2 Catalyst: Effect of Pt2+–Pt4+ and Pt2+–Zr4+ Dipoles at Metal-Support Interface

Catalysis Letters - We present a Pt/ZrO2 catalyst that can operate in the harsh conditions of methane oxidation without being deactivated by SO2. XPS analysis of 1%Pt/ZrO2 catalyst revealed the...     

GA-based cloud resource estimation for agent-based execution of bag-of-tasks applications

Executing bag-of-tasks applications in multiple Cloud environments while satisfying both consumers’ budgets and deadlines poses the following challenges: How many resources and how many hours should be allocated? What types of resources are required? How to coordinate the distributed execution of bag-of-tasks applications in resources composed from multiple Cloud providers?. This work proposes a genetic algorithm for estimating suboptimal sets of resources and an agent-based approach for executing bag-of-tasks applications simultaneously constrained by budgets and deadlines. Agents (endowed with distributed algorithms) compose resources and coordinate the execution of bag-of-tasks applications. Empirical results demonstrate that the genetic algorithm can autonomously estimate sets of resources to execute budget-constrained and deadline-constrained bag-of-tasks applications composed of more economical (but slower) resources in the presence of loose deadlines, and more powerful (but more expensive) resources in the presence of large budgets. Furthermore, agents can efficiently and successfully execute randomly generated bag-of-tasks applications in multi-Cloud environments.     

Emissions from a diesel-bioethanol blend in an automotive diesel engine

Diesel emissions have been measured from an automotive engine using anhydrous bioethanol blended with conventional diesel, with 10% ethanol in volume and no additives. The resulting emissions have been compared with those from pure diesel. A stationary engine test bed, together with the instrumentation for measuring the most stringent regulated emissions (nitric oxides, total hydrocarbons and particulate matter) and the particle size distributions, allowed to study the effect of this blend on the engine performance and emissions under five different steady state operating conditions, selected from the transient cycle for light duty vehicles established in the European Emission Directive 70/220. Both the consideration of the thermochemical properties of the tested fuels and the computations of a chemical equilibrium model were helpful for the results analysis. These results proved that the use of this renewable component provides a significant reduction on particulate emissions, with no substantial increase in other gaseous emissions, which makes it helpful for contributing, on the one hand, to fulfil the European compromise of using more than 5.75% biofuels in 2010, and on the other hand, to stop the increase in particulate emissions caused by transportation as a consequence of the unceasing dieselization.     

A simple model matching for the stabilization of an inverted pendulum cart system

We present a simple model matching controller for the stabilization of the inverted pendulum cart system, assuming that the pendulum is initialized above the horizontal plane. The control strategy consists of forcing the closed‐loop system to behave as another nonlinear target system with some stability properties. To this end, we solve two matching conditions that allow us to shape a suitable target system. Having satisfied both matching conditions, the stabilizing controller is directly obtained from the proposed target system. The obtained close‐loop system is locally asymptotically exponentially stable, with a very large domain of attraction. Copyright © 2007 John Wiley & Sons, Ltd.     

Production of microporous resins for heavy‐metal removal. II. Functionalized polymers

Ion‐exchange polymers were used successfully in water‐treatment operations. In this study, three ion‐exchange resins based on 4‐vinylpyridine and divinylbenzene functionalized with N‐oxide groups were obtained. Their ion‐adsorption properties were measured in solutions containing chromium at concentrations of 4 and 500 ppm with column and batch equilibrium techniques. The removal efficiency of the chromium ions with HCl was observed to increase after the protonation of the N‐oxide groups. The resins could be reused after 10 cycles with the metal removal efficiency maintained at higher than 95%. These studies evidenced a strong correlation between the morphology and ionic group content in the resin and its chromium ion sorption capability. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Effect of the addition of calcium hydroxide on some characteristics of extruded products from blue maize (Zea mays L) using response surface methodology

The aim of this research was to study the effects of calcium hydroxide (0–0.2%) and screw speed (100–180 rpm) on the expansion index (EI), bulk density (BD), penetration force (PF) and specific mechanical energy (SME) values of blue maize meal extrudates. Blue maize meal was extruded using a commercial extruder (Brabender 20DN/8‐235‐00) with a compression screw ratio of 3:1. A second‐order, central composite experimental design was used. It was found that the EI and SME values decreased and the BD and PF values increased when the calcium hydroxide concentration was increased. The screw speed had a significant effect only on the SME and PF values. Quadratic model fitness was shown for all responses, with values of R² > 0.74, p of F (model) <0.01 and variability coefficient <13.3% (except for PF, 29.18%), and for almost all cases there was no lack of fit (p > 0.055). Calcium hydroxide concentration showed good correlation (p < 0.01) with EI (r = ?0.81), PF (r = 0.60), SME (r = ?0.76) and BD (r = 0.83). However, screw speed was marginally or not correlated (r < 0.36, p > 0.14) with the responses. The results suggest that it is possible to produce appropriate extruded products from blue maize fortified with calcium in an optimised calcium hydroxide concentration and screw speed range of 0.02–0.078% and 117–180 rpm respectively. © 2001 Society of Chemical Industry