Hydrogen production from soft-drink wastewater in an upflow anaerobic packed-bed reactor

The production of hydrogen from soft-drink wastewater in two upflow anaerobic packed-bed reactors was evaluated. The results show that soft-drink wastewater is a good source for hydrogen generation. Data from both reactors indicate that the reactor without medium containing macro- and micronutrients (R2) provided a higher hydrogen yield (3.5 mol H₂ mol⁻¹ of sucrose) as compared to the reactor (R1) with a nutrient-containing medium (3.3 mol H₂ mol⁻¹ of sucrose). Reactor R2 continuously produced hydrogen, whereas reactor R1 exhibited a short period of production and produced lower amounts of hydrogen. Better hydrogen production rates and percentages of biogas were also observed for reactor R2, which produced 0.4 L h⁻¹ L⁻¹ and 15.8% of H₂, compared to reactor R1, which produced 0.2 L h⁻¹ L⁻¹ and 2.6% of H₂. The difference in performance between the reactors was likely due to changes in the metabolic pathway for hydrogen production and decreases in bed porosity as a result of excessive biomass growth in reactor R1. Molecular biological analyses of samples from reactors R1 and R2 indicated the presence of several microorganisms, including Clostridium (91% similarity), Enterobacter (93% similarity) and Klebsiella (97% similarity).     

An enhanced Lemaitre model formulation for materials processing damage computation

The Lemaitre damage model is now widely used to deal with coupled damage analyses for various mechanical applications. In this article, different extensions of the model are presented and discussed to deal with complex multiaxial configurations—such as multi-stages bulk forming processes. A specific treatment is done to account for compressive damage growth, and a stress triaxiality cut-off value is considered to avoid any damage evolution below a critical negative triaxiality. The damage potential is also modified to deal with highly ductile materials, and the plastic strain is split into a negative part and a positive part to differentiate damage growth for compressive states of stress and for tensile states of stress. Finally, an anisotropic damage approach based on the comparison between grain flow orientation and principal loading directions is defined. A combination of these extensions is achieved within a single Lemaitre formulation. Application on different examples show the robustness and accuracy of the model defined in this paper.     

Maintenance resources optimization applied to a manufacturing system

This paper presents an availability optimization of an engineering system assembled in a series configuration, with redundancy of units and corrective maintenance resources as optimization parameters. The aim is to reach maximum availability, considering as constraints installation and corrective maintenance costs, weight and volume. The optimization method uses a Genetic Algorithm based on biological concepts of species evolution. It is a robust method, as it does not converge to a local optimum. It does not require the use of differential calculus, thus facilitating computational implementation. Results indicate that the methodology is suitable to solve a wide range of engineering design problems involving allocation of redundancies and maintenance resources.     

Active and passive distraction using a head-mounted display helmet: Effects on cold pressor pain in children.

Objective: The current study tested the effectiveness of interactive versus passive distraction that was delivered via a virtual reality type head-mounted display helmet for children experiencing cold pressor pain. Design: Forty children, aged 5 to 13 years, underwent 1 or 2 baseline cold pressor trials followed by interactive distraction and passive distraction trials in counterbalanced order. Main Outcome Measures: Pain threshold and pain tolerance. Results: Children who experienced either passive or interactive distraction demonstrated significant improvements in both pain tolerance and pain threshold relative to their baseline scores. In contrast, children who underwent a second cold pressor trial without distraction showed no significant improvements in pain tolerance or threshold. Conclusion: Although both distraction conditions were effective, the interactive distraction condition was significantly more effective. Implications for the treatment of children's distress during painful medical procedures are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Research directions for service-oriented multiagent systems

Today's service-oriented systems realize many ideas from the research conducted a decade or so ago in multiagent systems. Because these two fields are so deeply connected, further advances in multiagent systems could feed into tomorrow's successful service-oriented computing approaches. This article describes a 15-year roadmap for service-oriented multiagent system research.     

Bilateral negotiation decisions with uncertain dynamic outside options

We present a model for bilateral negotiations that considers the uncertain and dynamic outside options. Outside options affect the negotiation strategies via their impact on the reservation price. The model is composed of three modules: single-threaded negotiations, synchronized multithreaded negotiations, and dynamic multithreaded negotiations. These three modules embody increased sophistication and complexity. The single-threaded negotiation model provides negotiation strategies without specifically considering outside options. The model of synchronized multithreaded negotiations builds on the single-threaded negotiation model and considers the presence of concurrently existing outside options. The model of dynamic multithreaded negotiations expands the synchronized multithreaded model by considering the uncertain outside options that may come dynamically in the future. Experimental analysis is provided to characterize the impact of outside options on the reservation price and thus on the negotiation strategy. The results show that the utility of a negotiator improves significantly if he/she considers outside options, and the average utility is higher when he/she considers both the concurrent outside options and the foresees future options.     

Coffee with jelly or unbuttered toast: Commissions and omissions are dissociable aspects of everyday action impairment in Alzheimer's disease.

Relative to our understanding of the memory and language deficits associated with Alzheimer's disease (AD), little is known about problems with everyday action performance (i.e., meal preparation, grooming). The resource theory proposes that everyday action problems are best explained by a unitary deficit in general cognitive resources. However, recent research suggests that omission and commission errors may reflect dissociable aspects of action impairment, with only omissions associated with resource limitations. This study examined everyday action performance in 70 participants with AD who also underwent a neuropsychological evaluation. First, correlation and principal component analyses were performed to examine the construct(s) that might explain everyday action impairment. Second, relations between everyday task component(s) and neuropsychological tests were examined by using correlation and regression analyses. Third, differences in everyday action error patterns were examined among participants of comparable overall impairment levels. Results showed omission and commission errors were uncorrelated and distinct components of everyday action performance, predicted by different neuropsychological tests, and differentially distributed even among participants with comparable overall impairment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Novel curing agents: Thermal radical initiators as viable alternatives to peroxides

Stable 1-pack coating systems are gaining importance at the expense of short-potlife 2-pack formulations. Two processes can initiate the cure mechanism: the action of heat and the action of UV-light. The use of heat has traditionally been the more popular process, as UV-curing still requires some investment and process modification on the part of customers willing to enter this market. In contrast to UV-curing, thermal curing ensures homogeneous cure on large 3D surfaces, as a result of the uniform distribution of heat all over the substrate.

Thermal curing of 1-pack coating systems is usually induced by polymerization of acrylates set off by peroxide initiators. The extreme exothermic reactivity of peroxides can result in an explosion if they are stored under unsuitable conditions (temperature increase). Another major but less dangerous drawback to using peroxide-containing 1-pack systems is their tendency to gel prematurely. The coating industry is therefore increasingly demanding a safe alternative to peroxides, i.e. non-explosive thermal radical initiators that combine good thermal stability and curing at relatively low temperature.

This paper describes a novel class of curing initiators, non-peroxide thermal radical initiators (TRI), and gives details of their reactivity, stability and coating performance when they are incorporated in 1-pack acrylate functionalized coating formulations.     

Effects of a Hindered Amine Stabilizer (HAS) on radiolytic and thermal stability of poly(methyl methacrylate)

Commercial Poly(methyl methacrylate) (PMMA) containing Tinuvin 622, a Hindered Amine Stabilizer (HAS), in 0.3% (wt/wt) concentration was investigated. The samples were irradiated with gamma radiation (⁶⁰Co) at room temperature in air. The viscosity‐average molecular weight (M_v) was analyzed by viscosity technique. Both control PMMA (without HAS) and PMMA + 622 (with HAS) showed a decrease in molecular weight with the increase in dose, reflecting the random scissions that occurred in the main chain. The G value (scissions/100 eV of energy transferred to the system) was also obtained by viscosity analysis. G value results showed that the addition of Tinuvin 622 into the PMMA matrix significantly decreased the number of scissions/100 eV at dose range of 0–60 kGy. Analysis of infrared spectra showed a decrease in the carbonyl index (CI) in irradiated samples. However the CI decrease was found lower for PMMA + 622 than for control PMMA sample. Thermogravimetric analysis (TGA) revealed that maximum decomposition temperature of additive PMMA is 42°C higher than control PMMA for unirradiated system. On the other hand this difference is not significant in irradiated systems at 60‐kGy irradiation dose. The activation energy of the thermal degradation of PMMA was 165 kJ/mol, this activation energy increased 60 kJ/mol when Tinuvin 622 was added to PMMA matrix. Therefore Tinuvin 622 is a suitable radiostabilizing agent for commercial PMMA in a 0–60 kGy dose interval. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Removal of Direct Yellow 27 Dye by Ionic Flocculation: The Use of an Environmentally Friendly Surfactant

The presence of dyes is one of the main contributors to the organic load in textile effluents. In this study a mixture of surfactants, produced from animal/vegetable fats, was used to remove the Direct Yellow 27 dye from a synthetic wastewater through an ionic flocculation process. It was evaluated the effect of contact time, temperature, and surfactant concentration on dye removal efficiency. It was also evaluated the kinetics, equilibrium, and diffusion mechanism of the process. The kinetics of the process was well described by both Pseudo-second order and Elovich models. The transport of dye molecules to the surfactant flocs is controlled by the external layer. Equilibrium data showed a good fit to the Langmuir model. A removal rate of 93% was achieved in a single stage, after 5 h of contact time.