Removal of toxic metal ions from aqueous systems by biosorptive flotation

Biosorptive flotation was used as a combined operation for the simultaneous abstraction of nickel, copper and zinc ions from aqueous streams. Laboratory‐scale batch experiments, as well as pilot‐scale continuous experiments, have been conducted. Grape stalks, a by‐product of the winery industry, were used as sorbent material. The experimental procedure consisted of two consecutive stages: (i) biosorption, and (ii) flotation. The possibility of reusing biomass, after appropriate elution, was also examined. The main parameters examined were biomass concentration, particle size of sorbent, surfactant concentration, pH and flocculation. Flotation removals, following laboratory‐scale experiments, were found to be in the order of 100, 85 and 70% for copper, zinc and nickel, respectively. In pilot‐scale experiments, biomass sorption capacities were determined as 25 for copper, 81 for zinc and 7 µmol dm^?3 for nickel. The order of biomass affinity regarding the studied metals was Cu > Zn > Ni. Short retention time and high effectiveness suggest that biosorptive flotation is a promising treatment process for the removal of toxic metals from contaminated aqueous solutions. © 2002 Society of Chemical Industry     

Patient effective dose and radiogenic risks from fluoroscopically assisted surgical reconstruction of femoral fractures

The objectives were to assess patient effective radiation dose from fluoroscopically guided surgical reconstruction of femoral fractures and provide normalized data for the estimation of patient effective dose and risks associated with such procedures performed in any laboratory. The fluoroscopic control required during surgical reconstruction of femoral fractures was classified into two types identified by beam orientation, i.e., posterior-anterior (PA) and lateral crosstable (LC) exposures. The duration and the dose area product (DAP) of each exposure were monitored in 24 patients with femoral fractures. Patient dose per DAP unit and per minute of fluoroscopy were measured at 14 radiosensitive organs/tissues using an anthropomorphic phantom and thermoluminescence dosimetry. The typical effective dose to patients with femoral fracture treated surgically in our institution was 11.6-21.7 microSv. This effective dose is estimated to cause an excess of 1.4 fatal cancers per million patients treated, and an excess of 0.4 hereditary disorders per million of births. Induction of deterministic skin injuries to treated patients is highly improbable at the dose levels found in this study. Patient effective dose and associated risks from a typical fluoroscopically guided surgical fixation of femoral fracture are low. However, they may be significantly elevated if treated patients are young individuals and/or the fluoroscopic exposure is prolonged. The present data may be used to determine effective dose to patients undergoing surgical reconstruction of femoral fracture in any institution.     

Virtual agent multimodal mimicry of humans

This work is about multimodal and expressive synthesis on virtual agents, based on the analysis of actions performed by human users. As input we consider the image sequence of the recorded human behavior. Computer vision and image processing techniques are incorporated in order to detect cues needed for expressivity features extraction. The multimodality of the approach lies in the fact that both facial and gestural aspects of the user’s behavior are analyzed and processed. The mimicry consists of perception, interpretation, planning and animation of the expressions shown by the human, resulting not in an exact duplicate rather than an expressive model of the user’s original behavior.     

COVERAGE: detecting and reacting to worm epidemics using cooperation and validation

Cooperative defensive systems communicate and cooperate in their response to worm attacks, but determine the presence of a worm attack solely on local information. Distributed worm detection and immunization systems track suspicious behavior at multiple cooperating nodes to determine whether a worm attack is in progress. Earlier work has shown that cooperative systems can respond quickly to day-zero worms, while distributed detection systems allow detectors to be more conservative (i.e., paranoid) about potential attacks because they manage false alarms efficiently. In this paper we present our investigation into the complex tradeoffs in such systems between communication costs, computation overhead, accuracy of the local tests, estimation of viral virulence, and the fraction of the network infected before the attack crests. We evaluate the effectiveness of different system configurations in various simulations. Our experiments show that distributed algorithms are better able to balance effectiveness against worms and viruses with reduced cost in computation and communication when faced with false alarms. Furthermore, cooperative, distributed systems seem more robust against malicious participants in the immunization system than earlier cooperative but non-distributed approaches.     

Decentralized Navigation Functions for Multiple Robotic Agents with Limited Sensing Capabilities

The decentralized navigation function methodology, established in our previous work for navigation of multiple holonomic agents with global sensing capabilities is extended to the case of local sensing capabilities. Each agent plans its actions without knowing the destinations of the others and the positions of those agents lying outside its sensing neighborhood. The stability properties of the closed loop system are checked via Lyapunov stability techniques for nonsmooth systems. The collision avoidance and global convergence properties are verified through simulations. This work was partially presented in [5].     

Error rate performance analysis of dual-hop relaying transmissions over generalized-K fading channels

In this paper we present analytical expressions for the lower bounds of the error performance of dual-hop amplify-and-forward transmissions over independent and not necessarily identical Generalized-K fading channels. Using a tight upper bound for the end-to-end SNR, a novel expression for the probability density function is derived. Based on the abovementioned formula, tight lower bounds for the average bit error probability for a variety of modulation schemes are derived. In order to validate the accuracy of the proposed mathematical analysis, various numerical and computer simulation results are presented.     

Composition and Antioxidant Activity of Olive Leaf Extracts from Greek Olive Cultivars

The olive leaf phenolic composition of the Greek cultivars koroneiki, megaritiki and kalamon was determined using LC/MS. Furthermore, the antioxidant activity of olive leaf extracts from the above three cultivars, using solvents of increasing polarity (petroleum ether, dichloromethane, methanol and methanol/water: 60/40) was evaluated using the stable free radical diphenylpicrylhydrazyl (DPPH) test. Furthermore the oxidative stability index (OSI) was compared to that of the synthetic antioxidant TBHQ and commercial oleoresin (rosemary extract). The ability of phenolic compounds to inhibit the lipoxygenase (LOX) activity was also investigated. The ten main components determined in the olive tree leaf extracts for the cultivars koroneiki and kalamon were: secologanoside, dimethyloleuropein, oleuropein diglucoside, luteolin-7-O-glucoside, rutin, oleuropein, oleuroside, quercetin, ligstroside and verbascoside. Respective compounds for the cultivar megaritiki were: secologanoside, dimethyloleuropein, oleuropein diglucoside, luteolin7-O-glucoside, oleuropein, oleuroside, quercetin and ligstroside. In all three cultivars, oleuropein represented the main phenolic component. The solvent polarity influenced the total amount of the phenolic compounds determined. When methanol/water (60/40) was used, as solvent, more phenolic compounds were determined. The total amounts of phenols determined in the extracts, obtained by successive extractions using the above solvents, were 6,094, 5,579 and 6,196 mg/kg (mg gallic acid/kg dried olive leaves) for the cultivars megaritiki, kalamon and koroneiki, respectively. Among all extracts, methanol/water extracts exhibited the highest antioxidant activity as shown through the application of the DPPH and OSI methods. The OSI antioxidant activity followed the sequence: synthetic antioxidant TBHQ > commercial oleoresin > olive tree leaf extracts > control. Likewise, methanol/water olive leaf extracts significantly inhibited soybean lipoxygenase, although some small differences in the activity among the olive leaf extracts of the different cultivars were observed. The solvent polarity as well as the amount of the extract influenced the inhibitory activity. A positive correlation was shown between the antioxidant activity of leaf extracts and the total phenol content.     

Bonding behaviour of chemically modified wood particles for board production

The objective of this paper was to evaluate the bonding behaviour of chemically modified wood particles towards an isocyanate resin system, as determined from internal bond strength of the board, and to determine which resin system, isocyanate or formaldehyde is suitable for use in boards made from modified raw material. It was found that chemical modification of wood chips and strands did not significantly affect the bonding efficiency of isocyanate resin, but the bonding efficiency of formaldehyde resins was strongly influenced. This behaviour can be a consequence of the usage of a less pH dependent resin that is fully cured during hot pressing in combination with the high mobility of the resin which causes penetration to considerable depth into compressed particles repairing weak zones, which are created during the modification process as chips are exposed to elevated temperatures, by sticking them together. It is suggested therefore, that the isocyanate resin system is more suitable for use in boards made from modified raw material than the formaldehyde resin system.     

Ubiquitous Agents for Ambient Ecologies

The cost of state-of-the-art devices and robots is critical for the uptake of Ambient Intelligence (AmI). One way to utilize low-cost hardware for both devices and robots is to run smart software remotely as agents deployed on computationally rich environments. In this context, the devices and the robots can be seen as the Avatars of agents, while the way devices and agents are related may be considered as an Ambient Ecology. We show how the application of a middleware platform called EVATAR realizes this vision by exemplifying the main issues with a multi-robot and a smart-home scenarios.