RESUMEN
We present a thorough study on the various impacts of polymer:nanoparticle ratios on morphology, charge generation and device performance in hybrid solar cells, comprising active layers consisting of a conjugated polymer and in situ prepared copper indium sulfide (CIS) nanoparticles. We conducted morphological studies through transmission electron microscopy and transient absorption measurements to study charge generation in absorber layers with polymer:nanoparticle weight ratios ranging from 1:3 to 1:15. These data are correlated to the characteristic parameters of the prepared solar cells. To gain a deeper understanding of our experimental findings, three-dimensional drift-diffusion-based simulations were performed. Based on elaborate descriptions of the contributions of polymer and nanoparticle phase to device performances, our results suggest that a polymer:CIS volume ratio of 1:2 (weight ratio 1:9) is necessary to obtain a balanced hole and electron percolation. Also at higher CIS loadings the photocurrent remains surprisingly high due to the contribution of the CIS phase to the charge carrier generation.
RESUMEN
BACKGROUND: Catheter-associated infections markedly contribute to treatment failure in peritoneal dialysis (PD) patients. There is much controversy surrounding prophylactic strategies to prevent these infections. METHODS: In this nationwide multicenter study we analyzed strategies to prevent catheter-associated infections as performed in Austrian PD centers in 2006. A questionnaire was sent to all 23 PD centers in Austria. RESULTS: Ten different catheter models were used in the 332 patients being treated in the 23 Austrian PD centers. Systemic antibiotics prior to catheter placement were given by 17 of the 23 PD centers (glycopeptides, n = 7; cephalosporins, n = 10). Nasal swabs were taken preoperatively by 17 PD centers; nasal Staphylococcus aureus carriers were treated prophylactically with mupirocin cream in 15 of these centers. Dressing change was routinely performed in 318 of 332 chronic PD patients (nonocclusive film dressing, n = 58; gauze dressing, n = 260). Disinfectants for chronic exit-site care included povidone iodine (n = 155), sodium hypochlorite (n = 31), povidone iodine + sodium hypochlorite together (n = 102), and octenidine dihydrochloride/phenoxyethanol (n = 17). Water + non-disinfectant soap or 0.9% sodium chloride was administered as a cleansing agent to the exit site by 27 patients. Routine S. aureus screening (nasal and/or exit-site swabs) in chronic PD patients was performed in 12 PD centers; carriers were treated with mupirocin cream in 11 of these centers. Dialysis staff members were screened for S. aureus in 8 PD centers and spouses were screened for S. aureus in 5 PD centers. The overall exit-site infection rate was 1 episode/43.9 patient-months, tunnel infection rate was 1 episode/88.9 patient-months, and peritonitis rate was 1 episode/51.0 patient-months. Patients of centers that have installed a prophylaxis protocol for treating S. aureus carriers had lower mean infection rates compared with those not using such a protocol. CONCLUSION: Various individual prophylactic strategies are used to prevent catheter-associated infections in Austrian PD centers. Infection rates are within the range reported in the literature. There is still scope for improvement in some centers (e.g., by establishing a prophylaxis protocol).