Ferrofluid Lubrication of Compliant Polymeric Contacts: Effect of Non-homogeneous Magnetic Fields

This paper demonstrates a new route to control friction in the isoviscous elastic lubrication regime between compliant point contacts. For this aim, the superposition of non-homogeneous magnetic fields in ferrofluid lubricated contacts is proposed. Under appropriate conditions, a friction reduction is observed by simply displacing the magnetic field distribution in the flow direction towards the inlet of the contact. This friction reduction is associated with a lower Couette friction contribution as a result of the fact that surfaces become more separated under field. Experiments and simulations are in good qualitative agreement.     

On the influence of the shear deformation and boundary conditions on the transverse vibration of multi-walled carbon nanotubes

The vibrational properties of multi-walled carbon nanotubes (MWCNTs) are studied, especially the influence of the shear deformation and the boundary conditions on the non-coaxial frequencies. A high order continuum beam model is proposed, which can be applied to study the transverse vibrations of MWCNTs, including those that could have initial deformations due to defects or external actions. Using the model it was found that the non-coaxial intertube frequencies are independent of the shear deformation and the boundary conditions. This result is important considering that the concentric structure of MWCNTs is a crucial geometrical characteristic and a non-coaxial vibration would affect their electronic and optical properties.     

Facilitating insight into a simulation model using visualization and dynamic model previews

This paper shows how model simplification, by replacing iterative steps with unitary predictive equations, can enable dynamic interaction with a complex simulation process. Model previews extend the techniques of dynamic querying and query previews into the context of ad hoc simulation model exploration. A case study is presented within the domain of counter-current chromatography. The relatively novel method of insight evaluation was applied, given the exploratory nature of the task. The evaluation data show that the trade-off in accuracy is far outweighed by benefits of dynamic interaction. The number of insights gained using the enhanced interactive version of the computer model was more than six times higher than the number of insights gained using the basic version of the model. There was also a trend for dynamic interaction to facilitate insights of greater domain importance.     

Analysis of Grain Boundary Character in a Fine-Grained Nickel-Based Superalloy 718

In the current work, sheets of superalloy 718 were processed via thermomechanical route by hot and cold rolling, followed by annealing below the δ phase solvus temperature and precipitation hardening to optimum strength. Grain boundary character distribution throughout the processing was mapped via EBSD and its evolution discussed. The results show that it is possible to process the alloy to a fine grain size obtaining concomitantly a considerably high proportion of special boundaries Σ3, Σ9, and Σ27. The precipitation of δ phase presented a strong grain refining role, without significantly impairing the twinning mechanism and, consequently, the Σ3, Σ9, and Σ27 boundary formations.     

Evaluation of the peptide profile with a view to authenticating buffalo mozzarella cheese

Electrophoretic and chromatographic techniques were used to determine water‐soluble peptide profiles aiming to identify the adulteration of buffalo milk mozzarella cheese by the addition of cow's milk. Thus, cheeses were produced with contents of cow's milk varying from 0% to 100%, and the peptides extracted after production and after 20 days of refrigeration. Polyacrylamide gel electrophoresis under denaturing conditions in the presence of sodium dodecyl sulphate (SDS‐PAGE) identified a potential peptide marker of exclusively bovine origin with a size of about 21 kDa for the addition of cow's milk above 30%. Reverse‐phase high‐performance liquid chromatography (RP‐HPLC) indicated the existence of two potential peptides present in higher concentrations in buffalo milk and one exclusive for cow's milk, the latter making it possible to estimate the addition of cow's milk to buffalo milk. Six commercial brands of buffalo mozzarella cheese were evaluated, and indications of adulteration found in four of them.     

Immobilization of aloin encapsulated into liposomes in Layer-by-layer films for transdermal drug delivery

Layer-by-layer (LbL) films have been exploited in drug delivery systems that may be used in the form of patches, but the encapsulation of poor water soluble drugs and their release with a controlled rate are still major challenges to be faced. In this paper, we demonstrate the controlled release of aloin (barbaloin), an important component of the widely used Aloe vera, encapsulated into liposomes and immobilized in LbL films with a polyelectrolyte. With a systematic study using fluorescence spectroscopy of aloin release from solutions and from LbL films with different phospholipid liposomes, we inferred that optimized release was achieved with aloin incorporated into palmitoyl oleyl phosphatidyl glycerol (POPG) or dipalmitoyl phosphatidyl glycerol (DPPG) liposomes immobilized in LbL films. Significantly, with this optimized system aloin was almost completely released within 30 h, with a small release rate at the end, which followed a sharp release in the first 5 h. Upon comparing the rates of the distinct systems, we conclude that the main factors controlling the release are the electrostatic interactions involving the negatively charged phospholipids. Because these interactions can be tuned in LbL films, the approach used here opens the way for new drug delivery systems to be developed with fine control of the drug release.     

Distributed simulation of virtual workshops for the multi-site scheduling feasibility evaluation

In this article, a distributed simulation tool for the feasibility evaluation of multi-site scheduling is proposed. The application areas concern supply chains (SCs) or networks of distributed workshops. The distributed simulation of workshops, called virtual workshops, generates various problems of causality and of tasks execution coordination. These problems are addressed in the proposed distributed architecture by the use of High Level Architecture protocol guaranteeing the synchronisation and the chronology of events occurring in the distributed simulations. An application to a simple case of the SC organising the flow between three workshops shows the effectiveness of the distributed simulation tool.     

A PROMETHEE-based approach to portfolio selection problems

In this paper, we study the use of PROMETHEE outranking methods for portfolio selection problems. Starting from a new formulation of the PROMETHEE V method, we develop several alternative approaches based on the concepts of boundary portfolios and c-optimal portfolios. The proposed methods are compared in an extensive computational study. Results of these experiments show that methods based on the concept of c-optimal portfolios provide a good approximation to the (often computationally untractable) PROMETHEE ranking of all portfolios, while requiring only small computational effort even for large problems. For smaller problems, a PROMETHEE ranking of all boundary portfolios can be performed and provides a close approximation of the total ranking.