ABSTRACT
Colloidal quantum dots (QDs) are promising candidates for the next generation of photovoltaic (PV) technologies. Much of the progress in QD PVs is based on using PbS QDs, partly because they are stable under ambient conditions. There is considerable interest in extending this work to PbSe QDs, which have shown an enhanced photocurrent due to multiple exciton generation (MEG). One problem complicating such device-based studies is a poor stability of PbSe QDs toward exposure to ambient air. Here we develop a direct cation exchange synthesis to produce PbSe QDs with a large range of sizes and with in situ chloride and cadmium passivation. The synthesized QDs have excellent air stability, maintaining their photoluminescence quantum yield under ambient conditions for more than 30 days. Using these QDs, we fabricate high-performance solar cells without any protection and demonstrate a power conversion efficiency exceeding 6%, which is a current record for PbSe QD solar cells.
ABSTRACT
The purpose of this study is to evaluate the effectiveness of endoscopic dacryocystorhinostomy by the posterior lacrimal sac approach without use of lacrimal stents or harvest of mucosal flaps as a valid surgical procedure for the treatment of an obstruction of the lacrimal pathways. A retrospective evaluation was conducted in a cohort of 75 patients between 2007 and 2011. A total of 78 endoscopic dacryocystorhinostomies were analyzed in 75 patients. After a mean follow-up of 25.7 months (minimum 12 months), 93.3% had a complete relief of symptoms after surgery. Our experience appears to confirm that the endoscopic posterior lacrimal sac approach with no stent insertion or mucosal flaps creation is a good alternative to other known endoscopic procedures.
Subject(s)
Dacryocystorhinostomy/methods , Endoscopy , Nasolacrimal Duct , Adult , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Retrospective Studies , StentsABSTRACT
We report on photovoltaic cells based on ternary PbS(0.9)Se(0.1) quantum dots utilizing a heterojunction type device configuration. The best device shows an AM 1.5 power conversion efficiency of 4.25%. Furthermore, this ternary PbS(x)Se(1-x) quantum dot heterojunction device has a peak external quantum efficiency above 100% at 2.76 eV, approximately 2.7× the bandgap energy. The ternary quantum dots combine the higher short circuit currents of the binary PbSe system with the higher open circuit voltages of the binary PbS system.
ABSTRACT
OBJECTIVES: Evaluate the efficacy of endoscopic treatment in maxillary inverted papilloma (IP). METHODOLOGY: Between July 2002 - April 2008, 20 patients affected by maxillary localization of IP were treated in our Clinic. All patients underwent endoscopic treatment consisting of an endoscopic medial maxillectomy (simple or extended), or attachment-site endoscopic tumour surgery. RESULTS: The cohort was composed of 20 patients (male: 15, female: 5), mean age 58 years, and included 21 endoscopic resections of maxillary IP. Minimum follow-up: 24 months, mean follow-up: 50 months. We registered only 1 case of tumour persistence/recurrence after 15 months, which underwent a second endoscopic treatment. No association with malignant lesions was noted. The efficacy of the endoscopic treatment was 95% (19/20 cases) after primary surgery, and 100% after endoscopic revision. CONCLUSIONS: Our experience demonstrates the efficacy of endoscopic treatment in maxillary IP. Based On its reduced morbidity in comparison to external approaches and its good control of the disease, we consider it our standard treatment for maxillary-originated inverted papilloma.
