Scaling-up of the electrodeposition process of nano-composite coating for corrosion and wear protection

The codeposition of hard nanoparticles into metal matrix electrodeposits usually leads to the increase of the coating hardness and abrasion resistance and causes a change to the microstructure of the deposits leading to more compact, nanostructured coatings with an increased corrosion resistance. Very often the laboratory scale results are not easily transferable to an industrial scale due to the introduction of new process variables such as the geometry and the dimensions of the component to coat.The aim of the present work was the study, in laboratory scale, of nano-composite nickel matrix coatings containing SiC nanoparticles and the transfer of this technology in industrial scale. The deposits have been produced using a Watts type bath containing 20 g/l of nanoparticles, under galvanostatic conditions using a current density of 2 A/dm². The deposits have been studied regarding their microstructure, abrasion and corrosion resistance. Based on the satisfactory results of the laboratory tests, the second part of this work contains the scaling-up and the industrialization of the process and the electrodeposition of the composite coating on ship propeller models and profiles as well as on train axles. The prototype parts were tested under actual working conditions.     

Study of nanofiber scaffolds of PAA,PAA/CS,and PAA/ALG for its potential use in biotechnological applications

In recent times, electrospun nanofibers have been widely studied from several biotechnological approaches; in this work, poly(acrylic acid) (PAA) solutions mixed with chitosan and alginate were electrospun and characterized to determine the behavior of these fibers when used in combination with bacteria, different samples were incubated with the bacterial strains: Streptomyces spp., Micromonospora spp., and Escherichia coli and a OD600 test was performed. The formation of nanofibers via electrospinning and the physicochemical properties of the obtained fibers were evaluated. Results showed that the presence of chitosan enhanced the thermal stability of PAA, since PAA/alginate fibers lost 5% of their mass at 41°C, whereas PAA/chitosan lost this amount at around 125°C. The fibers demonstrated suitable characteristics to be used as a bacteria bioreactor.     

Stabilized β-Bi2O3 nanoparticles from (BiO)4CO3(OH)2 precursor and their photocatalytic properties under blue light

Stabilized tetragonal Bi₂O₃ nanoparticles (β-Bi₂O₃) were obtained by annealing treatments of amorphous Bi-based precursors, obtained by chemical precipitations, at temperatures between 350 and 450?°C. The formation of the stabilized β-Bi₂O₃ phase was possible by using (BiO)₄CO₃(OH)₂ while other precursors such as amorphous bismuth carbonate ((BiO)₂CO₃) and amorphous basic bismuth nitrate (Bi₆O₆(OH)₂(NO₃)₄·2H₂O) led to the formation of the thermodynamically stable monoclinic α-Bi₂O₃ and Bi₅O₇NO₃ phases. The Bi-based precursors were prepared by the chemical precipitation method at room temperature in ethylenediamine-solvent varying the HNO₃/Bi³⁺ molar ratio (10, 26 and 56). The physicochemical properties of the three as-prepared amorphous precursors and the formed-after-calcination β-Bi₂O₃, α-Bi₂O₃ and Bi₅O₇NO₃ phases were analyzed by X-ray diffraction, scanning electron microscopy, thermogravimetry, X-ray photoelectron spectroscopy (XPS), FTIR analysis, diffuse reflectance spectroscopy and surface area by BET method. The photocatalytic activity of all annealed solids containing the β-Bi₂O₃ phase was tested in the photodegradation of the indigo carmine (IC) dye under specific blue light. A schematic diagram of the Bi₂O₃ phases obtained as a function of the annealing conditions and initial amorphous precursor is proposed and explained in terms of the amount of CO₃^2-, NO₃^- and amine (ENH₂²⁺ ? ENH⁺) ions present in each bismuth precursor.     

Functional stabilization of cellulase by covalent modification with chitosan

Chitosan was linked to cellulase (EC 3.2.1.4) from Trichoderma viride by covalent conjugation to periodate‐activated carbohydrate moieties of the enzyme. The modified enzyme contained about 1.5 mol of polymer per mol of protein. The specific activity of the conjugate prepared was 39.8% of the native cellulase. The optimum pH and temperature for cellulase remained unaltered after modification. The thermostability was increased by 8.9 °C for the cellulase–chitosan complex. Thermal inactivation at different temperatures ranging from 65 °C to 80 °C was markedly increased for the polymer‐modified enzyme. The stability within the pH range 1.0–3.2 was also improved for the modified enzyme. © 2001 Society of Chemical Industry     

Effect of ethanol administration on fatty acid desaturation

The effect of ethanol on the fatty acid desaturation by rat liver has been studied using liquid diets of different composition. Acute ethanol administration increased triacylglycerols of total liver lipids, but did not modify significantly the lipidic composition of microsomes. The Δ6 and Δ5 desaturases were inhibited by ethanol whereas the Δ9 desaturase and fatty acid synthetase were apparently modified only by diet composition. NADH-cytochrome (cyt.) c reductase was partially inhibited, whereas NADH-cyt. b₅ reductase remained practically unaltered and NADPH-cyt. c reductase activity was enhanced. Decreased electrons supplied by the microsomal cyt. b₅ electron transport chain would not be the reason for the inhibition of Δ6 and Δ5 desaturases by ethanol.     

Self-adaptive systems: A survey of current approaches,research challenges and applications

Self-adaptive software is capable of evaluating and changing its own behavior, whenever the evaluation shows that the software is not accomplishing what it was intended to do, or when better functionality or performance may be possible. The topic of system adaptivity has been widely studied since the mid-60s and, over the past decade, several application areas and technologies relating to self-adaptivity have assumed greater importance. In all these initiatives, software has become the common element that introduces self-adaptability. Thus, the investigation of systematic software engineering approaches is necessary, in order to develop self-adaptive systems that may ideally be applied across multiple domains. The main goal of this study is to review recent progress on self-adaptivity from the standpoint of computer sciences and cybernetics, based on the analysis of state-of-the-art approaches reported in the literature. This review provides an over-arching, integrated view of computer science and software engineering foundations. Moreover, various methods and techniques currently applied in the design of self-adaptive systems are analyzed, as well as some European research initiatives and projects. Finally, the main bottlenecks for the effective application of self-adaptive technology, as well as a set of key research issues on this topic, are precisely identified, in order to overcome current constraints on the effective application of self-adaptivity in its emerging areas of application.     

Diagnosis of Active Systems by Automata-Based Reasoning Techniques

This paper presents a method for the diagnosis of active systems, these being a class of distributed asynchronous discrete-event systems, such as digital networks, communication networks, and power transmission protection systems. Formally, an active system is viewed as a network of communicating automata, where each automaton describes the behavior of a system component. The diagnostic method encompasses four steps, namely system modeling, reconstruction planning, behavior reconstruction, and diagnosis generation. System modeling formally defines the structure and behavior of system components, as well as the topology of the active system. Based on optimization criteria, reconstruction planning breaks down the problem of system behavior reconstruction into a hierarchical decomposition. Behavior reconstruction yields an intensional representation of all the dynamic behaviors that are consistent with the available system observation. Eventually, diagnosis generation extracts diagnostic information from the reconstructed behaviors. The diagnostic method is applied to a case study in the power transmission network domain. Unlike other proposals, our approach both deals with asynchronous events and does not require any global diagnoser to be built off-line. The method, which is substantiated by an ongoing implementation, is scalable, incremental, and amenable to parallelism, so that real size problems can be handled.     

Hot metal pretreatment by powder injection of lime‐based reagents

A mathematical model earlier proposed has been improved to predict the kinetics of multicomponent reactions in the hot metal pretreatment through the injection of reactive fluxes. It is assumed that there are two reaction zones along the flux injection operation: a transitory reaction between the rising particles and the bulk metal, and the permanent reaction between the metal and the top slag. A criterion to estimate the fraction of solids which will react with molten iron in a three‐phase jet (gas‐solid‐liquid) was considered; this fraction of solids carries out the transitory reaction. The model also takes into account the thermodynamic changes produced in the metal and slag due to the chemical reactions. Calculated results of the model are in good agreement with experimental results for the desulfurization of hot metal through the injection of CaO‐SiO₂‐CaF₂‐FeO‐Na₂O reagents at 1400 ‐ 1450 °C. Two kinds of hot metal were tested, one with a low carbon mass content of 3 % and the other with a high carbon mass content of 4.5 %.     

Use of the task configuration system (TCS) for the design and on-line optimization of power plants operating with variable loads

The main purpose of this work is to show the ability of the TCS (task configuration system) to perform both the design and the operation optimization of power plants. The TCS is a module that permits to set the main task of each one of the equipments of the system and consequently setting how they respond to variable loads. In this work, the TCS was applied to a micro cogeneration plant of 60 kW in which both the electrical and the thermal loads were variable. Primarily, the design optimization of the nominal power of the equipments and of the TCS configuration was performed for the loads and electricity/fuel costs assumed in the design. After this operational optimizations in cases where the loads and electricity/fuel costs were doubled and then halved in relation to the standard case were performed. The results presented the TCS in a very robust way in most of the cases even the operational conditions being very different from the originally assumed. Based on the results, it is possible to defend the use of the TCS to decrease the risk of high initial investments made in cogeneration systems.     

ST-Audit: guideline-based automatic auditing of electronic patient records

This work presents the ST-Audit system that audits a patient record for conformance to a particular clinical guideline. The system uses ST-Guide which models a guideline as a set of states and transitions. The audit system tries to find a path in the state/transition diagram that corresponds to the actions taken by the physician, taking into consideration issues such as the unavailability of all the data needed to evaluate the transitions. The system was used to audit an outpatient clinic regarding their procedure for hypertension treatment (using the VI JNC guideline for hypertension), and the results of the number of non-compliant actions were presented and discussed. A follow up auditing showed a small but statistically significant reduction on the number of non-compliant actions for patients treated after the first audit.