No abstract

During the last decade interest in dye-sensitized solar cells (DSC) has grown enormously. Electrical impedance spectroscopy (EIS) is an electrochemical technique commonly used for investigation of charge carrier dynamics in these photovoltaic devices. We used EIS for characterization of our DSC; moreover, symmetric cells with counter-counter or photo-photo electrodes were realized and measured in order to simplify impedance cell analysis by separating the contribution of counter and photoelectrode, respectively. In particular, we provided very accurate illumination of the photoelectrode symmetric cell, aiming to approach the experimental conditions of a complete cell. By fitting of experimental data, we obtained values for the charge transfer resistance at the counter-electrode and the electron percolation time at the photoelectrode. Moreover, the simulation of a whole cell, combining the data from the fitting procedures above, was in good agreement with experimental data

Successful treatment of prosthetic joint infections often requires multiple surgical interventions and prolonged antimicrobial therapy. However, in certain situations, a surgical approach may not be in the best interest of the patient. A conservative approach was used to treat 34 patients with prosthetic joint infection between 1995 and 2003. Diagnosis of infection was based on clinical-microbiological evidence, confirmed by (99)Tc-labelled leukocyte scintigraphy, and involved 12 Staphylococcus aureus infections, nine Staphylococcus epidermidis infections, two Enterococcus faecalis infections, two mixed infections (S. aureus plus Pseudomonas aeruginosa; S. epidermidis plus E. faecalis), with the infecting pathogen being unidentified for nine patients. Most infections were treated initially with intravenous or intramuscular teicoplanin +/- ciprofloxacin or rifampicin, followed by oral ciprofloxacin or minocycline plus rifampicin. The mean duration of antimicrobial therapy was 41.2 weeks. Overall, only three patients did not respond to therapy, and infection was controlled in the remaining 31 patients. Among these, no relapse was observed in 17 patients during follow-up for 9-57 months; improvement with early (within 6 months of antibiotic discontinuation) or late relapse was observed in seven and three patients, respectively; two patients improved clinically, but continued to receive antibiotic therapy; and two patients whose condition improved initially were lost after a 6-month follow-up following discontinuation of antibiotics. No patient complained of side effects requiring discontinuation of antibiotic therapy. The study confirmed that suppression of infection, with salvage of the infected device in an acceptably functional state, can be achieved in selected cases.

The vascular bed of a Leydig cell tumor is wider and the blood flow velocity is higher than that of a seminoma due to more regular neovascularization. In contrast, a seminoma presents large areas of necrosis due to irregular neovascularization. This explains the different PE and WiR values. Further studies involving larger patient populations are mandatory to confirm these encouraging preliminary results.

Dye solar cells with Co(III)/Co(II) redox mediators have been prepared. To obtain higher conversion efficiencies, the recombination between photoinjected electrons and Co(III) species was minimized by deposition of a thin Al2O3 blocking layer over the mesoporous TiO2 surface. Measurements of current-voltage characteristic curves, both under illumination and in dark conditions, together with electrochemical impedance spectroscopy demonstrate the great effectiveness of the addition of a blocking layer in cells containing cobalt based electrolyte, by substantially reducing the recombination current. The consequent power conversion efficiency increase is more than double, passing from 0.94% to 2.48% under 300 W m−2 AM 1.5 illumination.