Deciphering Charging Status, Absolute Quantum Efficiency, and Absorption Cross Section of Multicarrier States in Single Colloidal Quantum Dots.

Upon photo- or electrical-excitation, colloidal quantum dots (QDs) are often found in multicarrier states due to multiphoton absorption, photocharging, or imbalanced carrier injection of the QDs. While many of these multicarrier states are observed in single-dot spectroscopy, their properties are not well studied due to random charging/discharging, emission intensity intermittency, and uncontrolled surface defects of single QDs. Here we report in situ deciphering of the charging status, precisely assessing the absorption cross section, and determining the absolute emission quantum yield of monoexciton and biexciton states for neutral, positively charged, and negatively charged single core/shell CdSe/CdS QDs.

[Epidemiological analysis on rubella cases in Songyang County in 2004].

Objective: To know the epidemiological characteristics of rubella case reported in Songyang County in 2004, and to know new ways of rubella control.

Method: To analyze the epidemiology on the rubella cases reported in Songyang County in 2004.

Results: In 2004, 195 rubella cases were reported, and the reported rubella incidence was 84.