SCORe-CT: a new method for testing effectiveness of sulfide-control chemicals used in sewer systems

A new method for testing the effectiveness of chemical products for sulfide control in sewers is reported. The method, called SCORe-CT (Sewer Corrosion and Odour Research - Chemical Testing), consists of two specially designed laboratory-scale systems that mimic sulfide production in real rising main sewers, and a multi-phase and multi-facet testing protocol. The monitoring tools/methods include both routine chemical analysis of various sulfurous and carbonaceous compounds in liquid and their on-line monitoring using advanced sensors. Molecular methods and microelectrodes can also be employed to examine the microbial structure and activity of sewer biofilms. The SCORe-CT method is not proposed to replace field trials but to screen chemicals prior to their often costly trials/applications in field conditions. For effective chemicals the method helps to reveal the mechanisms involved, and assists with the design of optimal dosage strategies, which would significantly reduce application costs. In this paper, the method is explained in detail and demonstrated with several case studies.     

Operating point selection for primary and secondary users in cognitive radio networks

This paper addresses the problem of opportunistic access of secondary users to licensed spectrum in cognitive radio networks. In order to avoid interference to the licensed primary users, efficient spectrum detection methods need to be developed. For this purpose, in recent years several sensing techniques have been proposed to monitor and regulate the spectrum access to the shared spectrum resources. However, spectrum sensing may be affected by errors in the form of missed-detections (i.e., an occupied spectrum is erroneously detected as free) or false-alarms (i.e., a free spectrum is erroneously detected as occupied). These two magnitudes pose a tradeoff on the design of the spectrum sensing mechanisms meaning that low missed-detection can only be achieved at the expense of high false-alarm and vice versa. Thus, the network designers should adaptively tune the sensing techniques such that the highest perceived Quality of Service (QoS) is achieved by both primary and secondary users. In this paper, a framework is introduced for determining the sensing operating points. Also the definition of Grade-of-Service (GoS) metrics is adopted to the case of primary/secondary users spectrum sharing. It is shown that the operating points of the sensing mechanisms can be easily adjusted according to the current traffic load of both primary and secondary users so that the perceived GoS is maximized. In addition, the Erlang Capacity of the spectrum sharing system for both primary and secondary users is also evaluated considering the effects of erroneous sensing.     

Subclass problem-dependent design for error-correcting output codes

A common way to model multi-class classification problems is by means of Error-Correcting Output Codes (ECOC). Given a multi-class problem, the ECOC technique designs a code word for each class, where each position of the code identifies the membership of the class for a given binary problem. A classification decision is obtained by assigning the label of the class with the closest code. One of the main requirements of the ECOC design is that the base classifier is capable of splitting each sub-group of classes from each binary problem. However, we can not guarantee that a linear classifier model convex regions. Furthermore, non-linear classifiers also fail to manage some type of surfaces. In this paper, we present a novel strategy to model multi-class classification problems using sub-class information in the ECOC framework. Complex problems are solved by splitting the original set of classes into sub-classes, and embedding the binary problems in a problem-dependent ECOC design. Experimental results show that the proposed splitting procedure yields a better performance when the class overlap or the distribution of the training objects conceil the decision boundaries for the base classifier. The results are even more significant when one has a sufficiently large training size.     

Optimal control of voltage source converters under power system faults

For the integration of renewable energy in power systems, Voltage Source Converters (VSCs) must transfer power from a DC source to an AC grid with effective control of the DC voltage. An important demand is that the converters remain connected to the grid even under severe voltage perturbations. In these situations, the power transfer capability of the converter suffers a drastic reduction, which may cause over-voltages. In this paper, a multi-variable optimal control with anti-windup compensation is proposed with the aim of improving performance, especially under severe voltage faults. The proposed control scheme is evaluated by simulations using a detailed model of the VSC.     

Protease–Antiprotease Imbalance in Bronchiectasis

Airway inflammation plays a central role in bronchiectasis. Protease–antiprotease balance is crucial in bronchiectasis pathophysiology and increased presence of unopposed proteases activity may contribute to bronchiectasis onset and progression. Proteases’ over-reactivity and antiprotease deficiency may have a role in increasing inflammation in bronchiectasis airways and may lead to extracellular matrix degradation and tissue damage. Imbalances in serine proteases and matrix-metallo proteinases (MMPs) have been associated to bronchiectasis. Active neutrophil elastase has been associated with disease severity and poor long-term outcomes in this disease. Moreover, high levels of MMPs have been associated with radiological and disease severity. Finally, severe deficiency of α1-antitrypsin (AAT), as PiSZ and PiZZ (proteinase inhibitor SZ and ZZ) phenotype, have been associated with bronchiectasis development. Several treatments are under study to reduce protease activity in lungs. Molecules to inhibit neutrophil elastase activity have been developed in both oral or inhaled form, along with compounds inhibiting dipeptydil-peptidase 1, enzyme responsible for the activation of serine proteases. Finally, supplementation with AAT is in use for patients with severe deficiency. The identification of different targets of therapy within the protease–antiprotease balance contributes to a precision medicine approach in bronchiectasis and eventually interrupts and disrupts the vicious vortex which characterizes the disease.     

Electroless Palladium-Coated Polymer Scaffolds for Electrical Stimulation of Osteoblast-Like Saos-2 Cells

Three-dimensional porous scaffolds offer some advantages over conventional treatments for bone tissue engineering. Amongst all non-bioresorbable scaffolds, biocompatible metallic scaffolds are preferred over ceramic and polymeric scaffolds, as they can be used as electrodes with different electric field intensities (or voltages) for electric stimulation (ES). In the present work we have used a palladium-coated polymeric scaffold, generated by electroless deposition, as a bipolar electrode to electrically stimulate human osteoblast-like Saos-2 cells. Cells grown on palladium-coated polyurethane foams under ES presented higher proliferation than cells grown on foams without ES for up to 14 days. In addition, cells grown in both conditions were well adhered, with a flat appearance and a typical actin cytoskeleton distribution. However, after 28 days in culture, cells without ES were filling the entire structure, while cells under ES appeared rounded and not well adhered, a sign of cell death onset. Regarding osteoblast differentiation, ES seems to enhance the expression of early expressed genes. The results suggest that palladium-coated polyurethane foams may be good candidates for osteoblast scaffolds and demonstrate that ES enhances osteoblast proliferation up to 14 days and upregulate expression genes related to extracellular matrix formation.     

Flow Effects in Supramolecular Chirality

There are an increasing number of reports on the emergence of circular dichroic signals when solutions of J-aggregates are vortex-stirred. Some authors claim that the transfer of chirality from the macroscopic stirring vortex occurs at the level of electronic transitions. Others argue that the signal observed is not due to true circular dichroism (CD), but rather that it is an artifact due to combinations of linear polarization contributions. For both interpretations it is necessary to assume that the alignment by effect of flows dominates over the Brownian dynamics. Therefore, the topic belongs to supramolecular chemistry because the alignment in current flows can only occur for relatively large particles with an appropriate shape. The phenomenon is detected by CD spectroscopy, which itself is also the main hindrance, even controversial, in its study and interpretation. However, modern Mueller matrix polarimetry can solve some of the problems. The phenomenon has been explained using different scenarios; however, in some of the systems the experimental evidence only supports the model in which deformation (folding/torsion) of elastic soft-matter yields true CD. Here we discuss the role of the gradient of shear rates in the deformation of nano particles of soft matter to give chiral supramolecular structures, as the first step to explaining the phenomenon.