MnO2 Thin Film Electrodes for Enhanced Reliability of Thin Glass Capacitors

Many dielectric thin films for energy storage capacitors fail by thermal breakdown events under high‐field drive conditions. The lifetime of the device can be improved under conditions where the current path within the defect regions in dielectrics is eliminated. Self‐healing electrodes were developed by depositing a manganese dioxide (MnO₂) thin film between the glass substrate and an aluminum film. For this purpose, thin films of MnO₂ on boroaluminosilicate glass were fabricated via chemical solution deposition and heat‐treated at temperatures in the range 500°C–900°C. The α‐MnO₂ structure was stabilized by Ba²⁺ insertion to form the hollandite structure. The phase transition temperature of α‐MnO₂ to Mn₂O₃ is strongly dependent on the Ba concentration, with transition temperatures of 600°C and 675°C with Ba concentrations of [Ba]/[Mn] = 0.04 and 0.1, respectively. The electrical resistivity increased from 4.5 Ω·cm for MnO₂ to 10⁵ Ω·cm for Mn₂O₃. Both dielectric breakdown strength and the associated cleared aluminum electrode area increased with an MnO₂ interlayer between Al electrodes and the borosilicate glass. The enhancement in dielectric strength was related with self‐healing. The associated redox reaction between MnO₂ and Mn₂O₃ was also proved by RAMAN spectroscopy following dielectric breakdown.     

Flammability of wood plastic composites prepared from plastic waste

The flammability of wood plastic composites manufactured from recycled plastics was investigated by using the cone calorimetry technique. The peak of the heat release rate was 12% to 25% lower compared to references produced from pure polyethylene‐ and polypropylene‐based composites. The total heat capacity and mass loss rate were also smaller for recycled material compared to the references. The stability of the composites was improved due to the presence of various thermally stable compounds, eg, traces of fire retardants, pigments, and other additives and impurities that can be present in recycled material. Incorporation of carbon black into the secondary materials did not reduce the peak of the heat release rate, but the total heat capacity and mass loss rate decreased further.     

Bromine as an ash forming element in a fluidised bed boiler combusting solid recovered fuel

Plastic materials are the main sources of chlorine in solid recovered fuels (SRF). Chlorine is attributed to be the main initiator of slagging, fouling and corrosion in biomass and waste combustion as it lowers the melting point of ash forming matter and reacts chemically with the heat transfer surface steels. SRF may also contain sources of bromine in the form of brominated flame retardants (BFRs) applied in many plastics and textiles. Results presented in this paper from an experimental campaign at an 80 MW_th bubbling fluidised bed (BFB) boiler show that bromine is behaving in a similar manner as chlorine: bromine was found at the corrosion front in boiler membrane wall tubes, and as water soluble salts in aerosol samples collected from the furnace and electrostatic precipitator (ESP) ash. It is evident from these results and the data in the literature that most of the salts of bromine are, by both their fate and physical and chemical properties, similar to those of chlorine. It can be concluded that it if there is a source of bromine in the fuel corrosive high vapour pressure bromides can be formed analogously to chlorides.     

Preparation,characterization, and swelling and drug release properties of a crosslinked chitosan‐polycaprolactone gel

For applications in biotechnology to prepare biopolymers containing functional groups is essential. In addition, these materials have to be strong to provide physical support for practical applications. Recently, chitosan, polycaprolactone (PCL), and their various combinations were used for this purpose. In this work, we described the preparation and characterization of a new biodegradable polymeric gel containing chitosan and PCL. The gel preparation reactions were performed in suitable acetic acid solutions to obtain the products in high yields. A crosslinking agent was added to produce crosslinked gels. Swelling behavior of chitosan/PCL gels in different compositions was studied, and the results were compared. The chitosan/PCL gels show a rather large equilibrium swelling in water and in the phosphate buffered saline solution. Acrylic acid (AA) was added to these gels during preparation process to obtain a stable material for various applications. These polymeric gels were characterized by Fourier transform infrared. Their physical and morphological properties were investigated by using differential scanning calorimeter and scanning electron microscope techniques, respectively. Cell growth experiments indicate that chitosan, a positively charged polysaccharide, is not suitable for cell proliferation studies. On the other hand, the drug release studies were successful and, 59% of lidocaine, was released from a chitosan/PCL/AA hydrogel in buffer solution at pH = 7.4 at 37°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A Novel Strategy as a Potential Rapid Therapy Modality in the Treatment of Corneal Ulcers: Fluconazole/Vancomycin Dual Drug-Loaded Nanofibrous Patches

Corneal ulcer, which is brought on by a breach in the epithelial barrier, is a dangerous infection of the avascular corneal stroma. New treatment strategies are needed, suppressing the aggressive nature of the disease and including a combination of different drugs. In this study, vancomycin (VAN) and fluconazole (FLU) dual-drug loaded dual-layered polyvinyl alcohol and gelatin (PVA/GEL) nanofibrous patches are produced by electrospinning. Scanning electron microscopy (SEM) images show smooth surfaces are obtained for both pure and drug-loaded nanofibrous patches. The tensile test results report that loading the FLU and VAN separately into the PVA/GEL patches decrease both the tensile strength and elongation at break and it is further reduced when combining two drug-loaded layers in one patch. According to drug release results, the FLU and VAN-loaded nanofibrous patches show a controlled release profile extending up to 96 h. Moreover, PVA/GEL/FLU, PVA/GEL/VAN, and PVA/GEL/FLU/VAN nanofibrous patches display significant antimicrobial activity against Candida albicans and Staphylococcus aureus. SEM, 4'-6diamidynofenyloindol (DAPI) staining, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay show that PVA/FLU and PVA/GEL/FLU/VAN nanofibrous patches have a superior effect on NIH3T3 cell spreading and proliferation. The novelty of this study lays in the development of a potential dual drug rapid treatment for corneal ulcers of aggressive nature.     

Nickel sorption by acclimatized activated sludge culture

The sorption of Ni(2+) by acclimatized activated sludge treating Ni(2+) bearing wastewater was investigated using a once-through completely mixed tank reactor. The culture developed from sewage was acclimatized to 85.2 microM/l Ni(2+) influent concentration by stepwise increases, at a low dilution rate 0.11/h. Acclimation was found to enhance the sorptive capacity of the activated sludge. In fact, at all of the intermediate concentrations, percentage Ni(2+) adsorbed by the biomass and also the sorptive capacity of the activated sludge drastically increased with an increase in the influent Ni(2+) concentration. All influent Ni(2+) concentrations were found to significantly stimulate the observed biomass yield of the culture over that observed in the base line. Experimental findings obtained at two other dilution rates; namely, 0.25/h and 0.45/h revealed that dilution rate is a significant operational parameter affecting the Ni(2+) sorption characteristics of acclimatized activated sludge microorganisms. Considerable complexation of nickel and organic and inorganic ligands in the wastewater appeared to be responsible for a relatively lower Ni(2+) sorption capacity.     

Intercomparison of air quality data using principal component analysis, and forecasting of PM₁₀ and PM₂.₅ concentrations using artificial neural networks, in Thessaloniki and Helsinki

In this paper we propose a methodology consisting of specific computational intelligence methods, i.e. principal component analysis and artificial neural networks, in order to inter-compare air quality and meteorological data, and to forecast the concentration levels for environmental parameters of interest (air pollutants). We demonstrate these methods to data monitored in the urban areas of Thessaloniki and Helsinki in Greece and Finland, respectively. For this purpose, we applied the principal component analysis method in order to inter-compare the patterns of air pollution in the two selected cities. Then, we proceeded with the development of air quality forecasting models for both studied areas. On this basis, we formulated and employed a novel hybrid scheme in the selection process of input variables for the forecasting models, involving a combination of linear regression and artificial neural networks (multi-layer perceptron) models. The latter ones were used for the forecasting of the daily mean concentrations of PM₁₀ and PM_2.5 for the next day. Results demonstrated an index of agreement between measured and modelled daily averaged PM₁₀ concentrations, between 0.80 and 0.85, while the kappa index for the forecasting of the daily averaged PM₁₀ concentrations reached 60% for both cities. Compared with previous corresponding studies, these statistical parameters indicate an improved performance of air quality parameters forecasting. It was also found that the performance of the models for the forecasting of the daily mean concentrations of PM₁₀ was not substantially different for both cities, despite the major differences of the two urban environments under consideration.     

Evaluation of a multiple regression model for the forecasting of the concentrations of NOx and PM10 in Athens and Helsinki

Forecasting models based on stepwise multiple linear regression (MLR) have been developed for Athens and Helsinki. The predictor variables were the hourly concentrations of pollutants (NO, NO₂, NO_x, CO, O₃, PM_2.5 and PM₁₀) and the meteorological variables (ambient temperature, wind speed/direction, and relative humidity) and in case of Helsinki also Monin-Obukhov length and mixing height of the present day. The variables to be forecasted are the maximum hourly concentrations of PM₁₀ and NO_x, and the daily average PM₁₀ concentrations of the next day. The meteorological pre-processing model MPP-FMI was used for computing the Monin-Obukhov length and the mixing height. The limitations of such statistical models include the persistence of both the meteorological and air quality situation; the model cannot account for rapid changes (on a temporal scale of hours or less than a day) that are commonly associated, e.g., with meteorological fronts, or episodes of a long-range transport origin. We have selected the input data for the model from one urban background and one urban traffic station both in Athens and Helsinki, in 2005. We have used various statistical evaluation parameters to analyze the performance of the models, and inter-compared the performance of the predictions for both cities. Forecasts from the MLR model were also compared to those from an Artificial Neural Network model (ANN) to investigate, if there are substantial gains that might justify the additional computational effort. The best predictor variables for both cities were the concentrations of NO_x and PM₁₀ during the evening hours as well as wind speed, and the Monin-Obukhov length. In Athens, the index of agreement (IA) for NO_x ranged from 0.77 to 0.84 and from 0.69 to 0.72, in the warm and cold periods of the year. In Helsinki, the corresponding values of IA ranged from 0.32 to 0.82 and from 0.67 to 0.86 for the warm and cold periods. In case of Helsinki the model accuracy was expectedly better on the average, when Monin-Obukhov length and mixing height were included as predictor variables. The models provide better forecasts of the daily average concentration, compared with the maximum hourly concentration for PM₁₀. The results derived by the ANN model where only slightly better than the ones derived by the MLR methodology. The results therefore suggest that the MLR methodology is a useful and fairly accurate tool for regulatory purposes.     

Comparison between rabbit lines for sensory meat quality

Rabbits from three synthetic lines were used in the experiment. Line R was selected for growth for 24 generations. Lines V and A were selected for litter size at weaning for 30 and 33 generations, respectively. Sensory analysis was carried out on the Longissimus muscle. The parameters evaluated were: juiciness (J), hardness (H), fibrousness (F), flouriness (Fl), intensity of rabbit flavour (IRF), aniseed odour (AO), aniseed flavour (AF), liver odour (LO) and liver flavour (LF). A Bayesian analysis was performed. Line V was only 82% as juicy as line R. Line V was 18% harder and 17% more fibrous than line R. Lines A and R had the same H and F. No differences in Fl were found. Small effects were found for flavour traits. We conclude that line origin has an influence on some sensory traits determining rabbit meat tenderness.     

High level of antimicrobial resistance in Campylobacter jejuni isolated from broiler chickens in Estonia in 2005 and 2006

The development of antimicrobial resistance in Campylobacter jejuni and Campylobacter coli is a matter of increasing concern. Because campylobacteriosis is transmitted to humans usually via food of animal origin, the presence of antimicrobial-resistant campylobacters in broiler chickens has important public health implications. The aim of our study was to analyze resistance patterns of C. jejuni isolated from fecal samples collected at a large Estonian chicken farm, from cecal contents collected at slaughterhouses, and from meat samples collected at the retail establishments in 2005 and 2006. A total of 131 C. jejuni isolates were collected over a 13-month period and tested by the broth microdilution VetMIC method (National Veterinary Institute, Uppsala, Sweden) to determine the MICs of various antimicrobials. Resistance to one or more antimicrobials was detected in 104 (79.4%) of the 131 isolates. High proportions of the isolates were resistant to enrofloxacin (73.3%) and nalidixic acid (75.6%). Multidrug resistance (resistance to three or more unrelated antimicrobials) was detected in 36 isolates (27.5%), all of which were resistant to enrofloxacin. Multidrug resistance was significantly associated with enrofloxacin resistance (P < 0.01), and the use of enrofloxacin may select for multiresistant strains.