Denitrifying polyphosphate accumulating organisms population and nitrite reductase gene diversity shift in a DEPHANOX-type activated sludge system fed with municipal wastewater

Enhanced biological phosphorus removal (EBPR) is a widely applied method for nutrients removal, although little is known about the key genes regulating the complex biochemical transformations occurring in activated sludge during phosphorus removal. In the present study, the nitrite reductase gene (nirS) diversity and the denitrifying polyphosphate accumulating organisms (DPAOs) population, grown in a bench scale, two-sludge, continuous flow plant, operating for biological anoxic phosphorus removal (DEPHANOX-type), fed with municipal wastewater, were examined by means of physicochemical analyses and the application of molecular techniques. The DEPHANOX configuration highly influenced biomass phosphorus as well as polyhydroxyalkanoates content and facilitated the enrichment of the DPAOs population. The application of double probe fluorescent in situ hybridization (double probe FISH) technique revealed that DPAOs comprised 20% of the total bacterial population. Based on clone libraries construction and nirS gene sequencing analysis, a pronounced shift in denitrifying bacteria diversity was identified during activated sludge acclimatization. Moreover, nirS gene sequences distinct from those detected in any known bacterial strain or environmental clone were identified. This is the first report studying the microbial properties of activated sludge in a DEPHANOX-type system using molecular techniques.     

The <Emphasis Type="Italic">α</Emphasis> − λ − <Emphasis Type="Italic">μ</Emphasis> and <Emphasis Type="Italic">α − η − μ</Emphasis> Small-Scale General Fading Distributions: A Unified Approach

In this paper, a general small-scale fading model for wireless communications, that explores the nonlinearity and at the same time the inhomogeneous nature of the propagation medium, is presented, studied in terms of its first-order statistics of the envelope, and validated by means of field measurements and the Monte Carlo simulation. It is indeed a novel distribution with many advantages such as its generality, its physical interpretation that is directly associated with the propagation channel, and its mathematical tractability due to its simple and closed-form expression. By fitting to measurement data, it has been shown that the proposed distribution outperforms the widely known fading distributions. Namely, the α − λ − μ model, which can be in fact called α − η − μ format 2 model, can also be obtained from the α − η − μ format 1 model by a rotation of the axes. Both formats are combined, in order to result to a unified model in a closed form that may describe the propagation environment in a variety of different fading conditions. Its physical background is hidden behind the names of its parameters. The unified model includes the already known general distributions α − μ′, η − μ, λ − μ (η − μ format 2), and their inclusive ones as special cases.     

Effect of pre‐treatment and smoking process (cold and hot) on chemical,microbiological and sensory quality of mackerel (Scomber scombrus)

The sensory, hygienic, toxicological and nutritional profiles of hot‐ and cold‐smoked mackerel samples were studied with various pre‐treatments. The panellists assessed all smoked samples as barely to quite acceptable products whilst the product immersed in 120 g kg^?1 sodium chloride and 60 g kg^?1 fructose prior to smoking was assessed as very acceptable regarding its sensory characteristics. The available lysine in all hot smoked samples was reduced to the same extent (32%) whilst a very good correlation (r = 0.912) was observed between loss of available lysine and colour formation of the cold‐smoked products, indicating the high contribution of lysine in the interactions with carbonyls. Histamine was found in highly unacceptable levels even in the unprocessed samples (600 mg kg^?1) and strongly increased (2220 and 2250 mg kg^?1) in the cold‐ and hot‐smoked samples, respectively, due to all treatments. These are levels which would be expected to cause symptoms of scombrotoxin poisoning. Benzo(a)pyrene, fluoranthene and perylene were at high levels both in cold‐ (2.1, 4.3 ± 0.04 and 7.2 ± 0.05 µg kg^?1) and hot‐smoked samples (9.2, 7.8 ± 0.03 and 9.4 ± 0.14 µg kg^?1, respectively) and were, as expected, influenced by the temperature. The aerobic bacteria remained at acceptable levels, since salt and high temperature prevent bacterial growth. Copyright © 2004 Society of Chemical Industry     

Thermomechanical Behavior of Multifunctional GFRP Sandwich Structures with Encapsulated Photovoltaic Cells

The feasibility of encapsulating solar cells into the glass fiber-reinforced polymer (GFRP) skins of load-bearing and thermally insulating sandwich elements with foam cores has been evaluated. Exposure of the encapsulated cells to artificial sunlight led to a significant temperature increase on the top sandwich surface, which almost reached the glass transition temperature of the resin. Mechanical loading up to serviceability limit loads did not cause any damage to the solar cells. Stresses of less than 20% of the material strength arose in the face sheets due to thermal and mechanical loading up to failure. Composite action through the face sheets with encapsulated cells was maintained and no debonding between face sheets and foam core was observed. Thanks to the superior mechanical and thermal sandwich behavior, thin-film silicon cells are more appropriate than polycrystalline silicon cells for use in multifunctional GFRP sandwich structures, although they are less efficient.     

Integrated biological hydrogen production

Biological systems offer a variety of ways by which to generate renewable energy. Among them, unicellular green algae have the ability to capture the visible portion of sunlight and store the energy as hydrogen (H₂). They hold promise in generating a renewable fuel from nature's most plentiful resources, sunlight and water. Anoxygenic photosynthetic bacteria have the ability of capturing the near infrared emission of sunlight to produce hydrogen while consuming small organic acids. Dark anaerobic fermentative bacteria consume carbohydrates, thus generating H₂ and small organic acids. Whereas efforts are under way to develop each of these individual systems, little effort has been undertaken to combine and integrate these various processes for increased efficiency and greater yields. This work addresses the development of an integrated biological hydrogen production process based on unicellular green algae, which are driven by the visible portion of the solar spectrum, coupled with purple photosynthetic bacteria, which are driven by the near infrared portion of the spectrum. Specific methods have been tested for the cocultivation and production of H₂ by the two different biological systems. Thus, a two-dimensional integration of photobiological H₂ production has been achieved, resulting in better solar irradiance utilization (visible and infrared) and integration of nutrient utilization for the cost-effective production of substantial amounts of hydrogen gas. Approaches are discussed for the cocultivation and coproduction of hydrogen in green algae and purple photosynthetic bacteria entailing broad utilization of the solar spectrum. The possibility to improve efficiency even further is discussed, with dark anaerobic fermentations of the photosynthetic biomass, enhancing the H₂ production process and providing a recursive link in the system to regenerate some of the original nutrients.     

Mathematical modeling of diffusion‐controlled free‐radical terpolymerization reactions

A comprehensive mathematical model is developed to describe the kinetics and molecular and compositional developments in a free‐radical terpolymerization batch reactor. This model is based on a fairly general kinetic mechanism, including chain‐transfer and terminal double‐bond reactions. We take into account the effects of diffusion‐controlled phenomena (i.e., gel, glass, and cage effects) on polymerization kinetics by extending our previous model on diffusion‐controlled reactions to terpolymerization systems. Triple moments for the live and dead trivariate chain‐length terpolymer composition distributions are introduced to describe the molecular and compositional developments in the terpolymerization system. The predictive capabilities of this model are demonstrated by simulation of the free‐radical, bulk terpolymerization of butyl acrylate/methyl methacrylate/vinyl acetate under different experimental conditions. It is shown that the model predictions are in good agreement with experimental data on monomer conversion, average molecular weights, and terpolymer composition, as reported by Dube and Penlidis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 161–176, 2003     

Measurement-adaptive cellular random access protocols

This work considers a single-cell random access channel (RACH) in cellular wireless networks. Communications over RACH take place when users try to connect to a base station during a handover or when establishing a new connection. Within the framework of Self-Organizing Networks (SONs), the system should self-adapt to dynamically changing environments (channel fading, mobility, etc.) without human intervention. For the performance improvement of the RACH procedure, we aim here at maximizing throughput or alternatively minimizing the user dropping rate. In the context of SON, we propose protocols which exploit information from measurements and user reports in order to estimate current values of the system unknowns and broadcast global action-related values to all users. The protocols suggest an optimal pair of user actions (transmission power and back-off probability) found by minimizing the drift of a certain function. Numerical results illustrate considerable benefits of the dropping rate, at a very low or even zero cost in power expenditure and delay, as well as the fast adaptability of the protocols to environment changes. Although the proposed protocol is designed to minimize primarily the amount of discarded users per cell, our framework allows for other variations (power or delay minimization) as well.     

The contents of proteins and phospholipids in cloudy (veiled) virgin olive oils

Extra virgin olive oil is produced in the form of a “suspension–dispersion” which can persist for several months before full deposition of a residue. Many consumers and chefs prefer unfiltered raw olive oil because it looks thicker and richer in flavors. The nature of the material in the suspension–dispersion is poorly described. The presence of proteins has been connected with the appearance of the “veiled” oil and also with its oxidative stability, although there are discrepancies in the literature with regard to their levels. The level of phosphorus, a measure of phospholipids, is also poorly studied. This work aims at quantifying proteins and phospholipids in cloudy olive oil. For the analysis of proteins, a practical method is used that can be applied for routine analysis. The proteins are precipitated with acetone and determined colorimetrically using the Bradford method suitably modified to measure protein dye‐binding at low concentrations. Twenty three virgin and one refined olive oil samples from different places in Greece were all found to have protein levels below 2.5 mg/kg. In most of the samples, values were lower after filtration of the cloudy oils. In the refined oil samples, protein was hardly determined (value ≤0.1 mg/kg). Phosphorus levels ranged from 0.8 to 4.8 mg/kg. These correspond to approximately 21–124 mg/kg of phospholipids. The results are discussed in relation to the oxidative and physicochemical stability of the veiled oils.     

Inhibition of Clostridium tyrobutyricum by Streptococcus macedonicus ACA-DC 198 under conditions mimicking Kasseri cheese production and ripening

Three fermentations in skim milk were used to study the effectiveness of the bacteriocin-producing Streptococcus macedonicus ACA-DC 198 strain to inhibit Clostridium tyrobutyricum LMG 1285T spore outgrowth under conditions prevailing during Kasseri cheese production and ripening. In fermentation A, Clostridium spores were used solely; in fermentation B, S. macedonicus ACA-DC 198 and Clostridium spores were used; in fermentation C, a commercial starter culture and Clostridium spores were used. The temperature program applied was similar to that of Kasseri cheese production and ripening. The presence of macedocin, the bacteriocin produced by S. macedonicus ACA-DC 198, was confirmed in fermentation B. The results showed that macedocin was able to inhibit the outgrowth of Clostridium spores, since significantly higher inhibition in spore outgrowth was detected in fermentation B than in fermentation C.