Sofia Azevedo

Synthesis of iron-doped TiO2 nanoparticles by ball-milling process : the influence of process parameters on the structural, optical, magnetic, and photocatalytic properties

Titanium dioxide (TiO2) absorbs only a small fraction of incoming sunlight in the visible region thus limiting its photocatalytic efficiency and concomitant photocatalytic ability. The large-scale application of TiO2 nanoparticles has been limited due to the need of using an ultraviolet excitation source to achieve high photocatalytic activity. The inclusion of foreign chemical elements in the TiO2 lattice can tune its band gap resulting in an absorption edge red-shifted to lower energies enhancing the photocatalytic performance in the visible region of the electromagnetic spectrum. In this research work, TiO2 nanoparticles were doped with iron powder in a planetary ball-milling system using stainless steel balls. The correlation between milling rotation speeds with structural and morphologic characteristics, optical and magnetic properties, and photocatalytic abilities of bare and Fe-doped TiO2 powders was studied and discussed.

On the refinement of use case models with variability support

Modeling software product lines shall imply modeling from different perspectives with different modeling artifacts such as use case diagrams, component diagrams, class diagrams, activity diagrams, sequence diagrams and others. In this paper, we elaborate on use cases for modeling product lines and we explore them from the perspective of variability by working with the unified modeling language (UML) «extend» relationship. We also explore them from the perspective of detail by (functionally) refining use cases with «extend» relationships between them. This paper’s intent is to provide for comprehension about use case modeling with functional refinement when variability is present.

Self-cleaning smart nanocoatings

Abstract: This chapter describes the major features of current smart, self-cleaning photocatalytic materials. These materials include semiconductor materials such as titanium dioxide (TiO2). This chapter focuses on TiO2-based materials because they are most widely studied. Characteristics such as low toxicity, high chemical stability, availability and low cost make TiO2 the ideal candidate for industrial applications.

Refinement of Software Product Line Architectures through Recursive Modeling Techniques

Currently, modeling methods applicable to software product line architectures do not explicitly comprise refinement, which implies dealing with a lot of complexity during their application to a high number of requirements. This paper suggests the extension of a modeling method applicable to product line architectural modeling, the 4SRS (Four Step Rule Set), to support the refinement of product lines. We have used the GoPhone case study to illustrate the approach and the recursion capability of the method as a solution to the challenges of modeling product line architectures. The strength of our approach resides in its stepwise nature and in allowing the modeler to work at the user requirements level without delving into lower abstraction concerns.

Electrochemical anodizing, structural and mechanical characterization of nanoporous alumina templates

Highly ordered Anodic Aluminum Oxide (AAO) structures produced from aluminum by using an electrochemical anodizing method were developed towards its application for the next generation of micro/nanomedical and energy devices. In addition of analyzing the anodizing current profile, the surface morphology was characterized by using Scanning Electron Microscopy (SEM), the crystalline structure by X-Ray Diffraction (XRD) and the mechanical properties by nanoindentation experiments. The anodizing time and applied potential determines the nanopores regularity and their size, although the effect of the potential is more pronounced than the effect of temperature in the transformation from crystalline alumina to amorphous alumina. Optimum pore growth was achieved with an applied potential of 17 V which led to a pore fraction - P(f) - of about 17.5%. The experimental Berkovich nanoindentation method was used to determine the AAO hardness as a function of the indenter depth, during the loading stage, using mechanical response and deformation behaviour of the nanopores structure. From the experimental data of the load-displacement curves, this method allows the calculation of the indenter contact depth at each reloading point, thus leading to the estimation of the materials hardness. The results reveal that the hardness depends on the processing conditions used for the production of the AAO samples that also strongly influences the organization and pore size uniformity.

Deposition of ITO Thin Films onto PMMA Substrates for Waveguide Based Biosensing Devices

Biosensors’ research filed has clearly been changing towards the production of multifunctional and innovative design concepts to address the needs related with sensitivity and selectivity of the devices. More recently, waveguide biosensors, that do not require any label procedure to detect biomolecules adsorbed on its surface, have been pointed out as one of the most promising technologies for the production of biosensing devices with enhanced performance. Moreover the combination of optical and electrochemical measurements through the integration of transparent and conducting oxides in the multilayer structures can greatly enhance the biosensors’ sensitivity. Furthermore, the integration of polymeric substrates may bring powerful advantages in comparison with silicon based ones. The biosensors will have a lower production costs being possible to disposable them after use (“one use sensor chip”). This research work represents a preliminary study about the influence of substrate temperature on the overall properties of ITO thin films deposited by DC magnetron sputtering onto 0,5 mm thick PMMA sheets.

High barrier plastics using nanoscale inorganic films

Abstract: Packaging materials for food containers need to fulfil extremely tight standards towards the fresh-like quality maintenance of packed products. Even though polymers are normally preferred for the production of packaging systems, their permeability to gases, water vapour and odours remains a concern. In this sense, new approaches using nanoscale effects are under development to design, create or model gas-barrier nanocoatings with significantly optimized properties. It is generally agreed that the final barrier performances of the deposited inorganic materials are strongly coupled with mechanical and morphological properties. Basically, a good barrier system should have a dense morphology without cracks, good adhesion to the substrate, low stress, uniform thickness and reproducibility. At the moment, researchers aim for development of cost effective mass production techniques.

The UML «extend» relationship as support for software variability

The development of software product lines with model-driven approaches involves dealing with diverse modeling artifacts such as use case diagrams, component diagrams, class diagrams, activity diagrams, sequence diagrams and others. In this paper we focus on use cases for product line development and we analyze them from the perspective of variability. In that context we explore the UML (Unified Modeling Language) «extend» relationship. This work allows understanding the activity of use case modeling with support for variability.

The UML «include» Relationship and the Functional Refinement of Use Cases

Developing software with model-driven approaches involves dealing with diverse modeling artifacts such as use case diagrams, component diagrams, class diagrams, activity diagrams, sequence diagrams and others. In this paper we focus on use cases for software development and we analyze them from the perspective of detail. In that context we explore the UML (Unified Modeling Language) «include» relationship. This work allows understanding the use case modeling activity with support for refinement and provides for specific guidelines on how to conduct such activity.

Smart self-cleaning coatings for corrosion protection

Abstract: Self-cleaning surfaces have attracted significant attention in recent years for their potential in both fundamental research and practical applications. Under the scope of self-cleaning smart coatings, this chapter explores the principal features of materials that can be used as protective coatings with an emphasis on the photocatalytic materials that have been developed to date. The chapter also highlights the importance of using titanium dioxide (TiO 2 ) as a semiconductor material in industrial applications since it can act as a photoanode for metal cathodic protection.