An enhanced deterministic beacon advertising algorithm for building TSCH networks

In this paper, we focus first on the time needed by a node to join a Time Slotted Channel Hopping (TSCH) network, this time is called joining time. Second, we are also interested in the network building time. Since the data generated by a sensor node remain unavailable as long as this node has not yet joined the wireless sensor network, these times are of prime importance for applications having strong latency requirements on data gathering. The joining time depends on the beacon advertising policy that has been left unspecified by the standard. The contribution of this paper is triple. First, we propose an Enhanced Deterministic Beacon Advertising algorithm, called EDBA, that ensures a collision-free advertising of beacons and minimizes the average joining time. Second, we model the behavior of a joining node by a Markov chain, validated by NS3 simulations, and compute the average joining time. Third, we compare the performance of EDBA with this of MBS, considered as the best beacon advertising algorithm in the literature.     

Review of Bioretention System Research and Design: Past, Present, and Future

This paper reviews the evolution of bioretention systems, a promising at-source storm-water best management practice. The introduction of bioretention systems in the 1990s by Prince George’s County, Md. is examined along with the motivations behind the development of the systems. A summary of the research findings on the performance of bioretention systems is provided including proposed design modifications to improve the field performance. Also included is an overview of past and current bioretention design guidelines in North America, as well as a discussion of issues surrounding the public adoption and implementation of bioretention systems. Potential alternative uses for the systems are highlighted and a review of bioretention modeling work is provided. Finally, the paper outlines research needs and anticipated future work necessary to bring about the widespread use of bioretention systems.     

Aquifex aeolicus membrane hydrogenase for hydrogen biooxidation: Role of lipids and physiological partners in enzyme stability and activity

Hydrogenase I from the hyperthermophilic bacterium Aquifex aeolicus is a good candidate for biotechnological devices thanks to its ability to oxidize hydrogen at high temperature, even in the presence of oxygen and CO. In order to enhance the enzyme stability and the catalytic efficiency, we investigated the hydrogen oxidation process with hydrogenase I embedded in a physiological-like environment. Hydrogenase I partners in the metabolic chain, namely membrane quinone and cytochrome b, were purified and fully characterized. The complex hydrogenase I–cytochrome b was inserted into liposomes. Surface Plasmon Resonance revealed that quinone took part in the stabilization of the complex. By use of molecular modelization and electrochemistry analysis, enzyme stability has been demonstrated to be stronger and enzymatic efficiency to be five times higher when hydrogenase is embedded into the liposomes. This result raises the possibility of using hydrogenases as biocatalysts in fuel cells.     

Incorporation of process integration into life cycle analysis for the production of biofuels

This article presents a new approach for incorporating process-integration tools into life cycle analysis (LCA) for biofuel production. Process synthesis techniques using mass- and energy-integration tools are employed to generate various scenarios for reducing mass and energy consumption in the process. The global implications of these changes and the associated trade-offs are assessed using the LCA tool: GREET. The developed approach enables the consideration of several levels of process integration while tracking the process economics and the reduction of the net greenhouse gas emissions. Several cases of biofuels with different processing technologies have been considered in this study, and the results show that when the process-integration tools are effectively utilized and combined with LCA, better insights are obtained and the net greenhouse gas emissions decrease drastically for different biofuels.     

Implication of scavenger receptors in the interactions between diesel exhaust particles and immature or mature dendritic cells

Background  

The exposure to pollutants such as diesel exhaust particles (DEP) is associated with an increased incidence of respiratory diseases. However, the mechanisms by which DEP have an effect on human health are not completely understood. In addition to their action on macrophages and airway epithelial cells, DEP also modulate the functions of dendritic cells (DC). These professional antigen-presenting cells are able to discriminate unmodified self from non-self thanks to pattern recognition receptors such as the Toll like Receptors (TLR) and Scavenger Receptors (SR). SR were originally identified by their ability to bind and internalize modified lipoproteins and microorganisms but also particles and TLR agonists. In this study, we assessed the implication of SR in the effects of DEP associated or not with TLR agonists on monocyte-derived DC (MDDC). For this, we studied the regulation of CD36, CXCL16, LOX-1, SR-A1 and SR-B1 expression on MDDC treated with DEP associated or not with TLR2, 3 and 4 ligands. Then, the capacity of SR ligands (dextran sulfate and maleylated-ovalbumin) to block the effects of DEP on the function of lipopolysaccharide (LPS)-activated DC has been evaluated.     

Life cycle assessment of a community hydroelectric power system in rural Thailand

Rural electrification and the provision of low cost, low emission technology in developing countries require decision makers to be well informed on the costs, appropriateness and environmental credentials of all available options. While cost and appropriateness are often shaped by observable local considerations, environmental considerations are increasingly influenced by global concerns which are more difficult to identify and convey to all stakeholders.Life cycle assessment is an iterative process used to analyse a product or system. This study iteratively applies life cycle assessment (LCA) to a 3 kW community hydroelectric system located in Huai Kra Thing (HKT) village in rural Thailand. The cradle to grave analysis models the hydropower scheme’s construction, operation and end of life phases over a period of twenty years and includes all relevant equipment, materials and transportation.The study results in the enumeration of the environmental credentials of the HKT hydropower system and highlights the need to place environmental performance, and LCA itself, in a proper context. In the broadest sense, LCA results for the HKT hydropower system are found to reflect a common trend reported in hydropower LCA literature, namely that smaller hydropower systems have a greater environmentally impact per kWh – perform less well environmentally - than larger systems. Placed within a rural electrification context, however, the HKT hydropower system yields better environmental and financial outcomes than diesel generator and grid connection alternatives.     

Evaluation of uncertainties in sewer condition assessment

Closed Circuit Television Inspection is used since decades as industry standard for sewer system inspection and structural performance evaluation. In current practice, inspection data are helpful to support asset management decisions. However, the quality and uncertainty of sewer condition assessment is rarely questioned. This article presents a methodology to determine the probability to underestimate, overestimate or accurately estimate the real condition of a pipe using visual inspection. The approach is based on the analysis of double inspections of the same sewer pipes and has been tested using the extensive data-set of the city of Braunschweig in Germany. Results indicate that the probability to inspect correctly a pipe in poor condition is close to 80%. The probability to overestimate the condition of a pipe in bad condition (false negative) is 20% whereas the probability to underestimate the condition of a pipe in good condition (false positive) is 15%. Finally, sewer condition evaluation can be used to assess the general condition of the network with an excellent accuracy probably because the respective effects of false positive and false negative are buffered.