Inactivation of Giardia muris cysts using medium-pressure ultraviolet radiation in filtered drinking water

The effect of medium pressure ultraviolet radiation on Giardia muris was studied using a collimated beam apparatus with filtered surface water from the Grand River, Kitchener, Ontario, Canada. UV doses ranged from 5 to 83 mJ/cm² and resulted in 2–3 log-units of reduction in infectivity measured by a C3H/HeN mouse infectivity model. In vitro excystation and nucleic acid staining with Live/Dead BacLight^™ greatly underestimated the inactivation of Giardia when compared with animal infectivity. Medium pressure ultraviolet radiation is a potential alternative to conventional chemical disinfection methods.     

Antioxidant and Antimicrobial Activities of Echinacea (Echinacea purpurea L.) Extracts Obtained by Classical and Ultrasound Extraction

Antioxidant and antimicrobial activities of Echinacea purpurea L. (Asteraceae) extracts obtained by classical and ultrasound solvent extraction were compared. The dry aerial part of plant was extracted by 70% ethanol at a solid-to-liquid ratio of 1:10 (m/v) and 25°C. The extract obtained by classical solvent extraction contained 29% larger amounts of phenolic compounds and 20% higher content of flavonoids. 2,2-diphenyl-1-picril hydrazyl radical (DPPH) scavenging reached 93.6% and the values of EC50 were (34.16±0.65) μg·ml⁻¹ and (65.48±1.12) μg·ml⁻¹ for the extracts obtained by the classical and ultrasound extractions, respectively. The extracts, independent of the extraction technique applied, showed a considerable growth inhibition on Candida albicans and Saccharomyces cerevisiae, while no growth inhibition zones were observed for Aspergillus niger. The diameters of inhibition zone observed for all the microorganisms were larger for extracts obtained by classical extraction than those by ultrasound extraction.     

The assessment of particle association and UV disinfection of wastewater using indigenous spore-forming bacteria

Studies have shown that association between particles and coliform bacteria in wastewater influence the inactivation of these microorganisms by ultraviolet (UV) irradiation. This research investigated the potential use of indigenous aerobic spore-forming (ASF) bacteria for studying the particle - microorganism interaction and its effect on UV disinfection of protozoan pathogens, such as Giardia spp. and Cryptosporidium spp., present in effluents from full-scale municipal wastewater treatment plants. The effect of particle - ASF association was determined by homogenizing wastewater effluent samples before and after exposure to controlled UV doses delivered by a bench-scale collimated beam apparatus. Particle association between Bacillus subtilis spores added to wastewater and wastewater particles was also assessed. The results indicate that spores are not significantly associated with wastewater particulate matter and particle association does not significantly affect the inactivation of indigenous spores present in wastewater by UV radiation in this study.     

Preparation of Y2O3:Eu nanopowders via polymer complex solution method and luminescence properties of the sintered ceramics

Herein we presented polymer complex solution method for production of well crystalline europium doped Y₂O₃ nanopowders. Polyethylene glycol (PEG) of five different molecular weights is used both as a fuel and as a nucleation agent for the crystallization. Powders were cold-pressed and sintered to obtain ceramics. SEM images taken from ceramic pellets indicate formation of a dense structure, with a pronounced grain growth and low pore concentration. Luminescence emission spectra of powders and ceramics are similar, and in good agreement with theoretical data. Lifetimes of Eu³⁺⁵D₀ level in nanocrystalline powders are higher compared to one observed in bulk, confirming in this case theory of lifetime lengthening in nanophosphors due to the change of effective refraction index. As expected, lifetime values in ceramic samples decrease toward the value in bulk Y₂O₃. The optical filling factor is calculated from observed decay times, providing a measure of discrepancy between powder and bulk state regarding their luminescent properties.     

Coordinated stabilizing control for the exciter and governor loops using fuzzy set theory and neural nets

This paper presents a design technique for a new hydropower plant controller using fuzzy set theory and artificial neural networks. The controller is suitable for real time operation, with the aim of improving the generating unit transients by acting through the exciter input, the guide vane and the runner blade positions. The developed fuzzy logic based controller (FLC) whose control signals are adjusted using the on-line measurements, can offer better damping effects for generator oscillations over a wider range of operating conditions than conventional regulators. Digital simulations of a hydropower plant equipped with a low-head Kaplan turbine are performed and the comparisons of conventional excitation-governor control, optimal state-feedback control and FLC performances are presented. The FLC, based on a set of fuzzy logic operations that are performed on controller inputs, provides a means of converting linguistic control requirements based on expert knowledge into an efficient control strategy. A fuzzy associative matrix is generated by using unsupervised learning of artificial neural networks. Results obtained on the nonlinear hydrounit mathematical model simulation demonstrate that the performance of the FLC closely agrees with that obtained if the optimal state-feedback multivariable discrete-time controller is applied.     

Synthesis of Hard Real-Time Application Specific Systems

This paper presents a system level approach for the synthesis of hard real-time multitask application specific systems. The algorithm takes into account task precedence constraints among multiple hard real-time tasks and targets a multiprocessor system consisting of a set of heterogeneous off-the-shelf processors. The optimization goal is to select a minimal cost multi-subset of processors while satisfying all the required timing and precedence constraints. There are three design phases: resource allocation, assignment, and scheduling. Since the resource allocation is a search for a minimal cost multi-subset of processors, we adopted an A* search based technique for the first synthesis phase. A variation of the force-directed optimization technique is used to assign a task to an allocated processor. The final scheduling of a hard-real time task is done by the task level scheduler which is based on Earliest Deadline First (EDF) scheduling policy. Our task level scheduler incorporates force-directed scheduling methodology to address the situations where EDF is not optimal. The experimental results on a variety of examples show that the approach is highly effective and efficient.