We have measured peak and spectrally integrated absolute absorption cross sections for the first (E11) and second (E22) optical transitions of seven semiconducting single-walled carbon nanotube (SWCNT) species in bulk suspensions. Species-specific concentrations were determined using short-wave IR fluorescence microscopy to directly count SWCNTs in a known sample volume. Measured cross sections per atom are inversely related to nanotube diameter. E11 cross sections are larger for mod 1 species than for mod 2; the opposite is found for E22.

Covalent doping of single-walled carbon nanotubes (SWCNTs) can modify their optical properties, enabling applications as single-photon emitters and bio-imaging agents. We report here a simple, quick, and controllable method for preparing oxygen-doped SWCNTs with desirable emission spectra. Aqueous nanotube dispersions are treated at room temperature with NaClO (bleach) and then UV-irradiated for less than one minute to achieve optimized O-doping. The doping efficiency is controlled by varying surfactant concentration and type, NaClO concentration, and irradiation dose. Photochemical action spectra indicate that doping involves reaction of SWCNT sidewalls with oxygen atoms formed by photolysis of ClO − ions. Variance spectroscopy of products reveals that most individual nanotubes in optimally treated samples show both pristine and doped emission. A continuous flow reactor is described that allows efficient preparation of milligram quantities of O-doped SWCNTs. Finally, we demonstrate a bio-imaging application that gives high contrast short-wavelength infrared fluorescence images of vasculature and lymphatic structures in mice injected with only ~100 ng of the doped nanotubes.

ABSTRACT. Objective. To evaluate the effect of treatment without aspirin in the acute phase of Kawasaki disease (KD) and to determine whether it is necessary to expose children to high-or medium-dose aspirin.Methods. A total of 162 patients who fulfilled the established criteria of acute KD between 1993 and 2003 were included in this retrospective study. All patients were treated with high-dose intravenous immunoglobulin (IVIG; 2 g/kg) as a single infusion without concomitant aspirin treatment. Low-dose aspirin (3-5 mg/kg per day) was subsequently prescribed when fever subsided. Patients who had defervescence within 3 days after the completion of IVIG treatment were classified as the IVIG-responsive group, and those whose fever persisted for >3 days were classified as the IVIG-nonresponsive group. The 162 patients were divided further into 2 groups: those who were treated with IVIG before illness day 5, and those who were treated after illness day 5. We compared the response rate of IVIG therapy, duration of fever, and incidence of coronary artery abnormalities (CAAs) between these groups.Results. A total of 153 patients were classified into the IVIG-responsive group, and 128 (83.66%) of them had defervescence within 24 hours after completion of IVIG therapy. Nine (5.56%) patients were classified into the IVIG nonresponsive group, and all received additional IVIG (2 g/kg) without aspirin. Six (66.67%) had defervescence within 3 days after additional therapy. Patients in the IVIG-nonresponsive group had a significantly higher incidence of CAAs than those in the IVIG-responsive group (25% vs 2.92%). In the group that was treated before illness day 5 (n ‫؍‬ 16), all patients had defervescence within 3 days after IVIG therapy and 13 (81.25%) had defervescence within 24 hours. In the group that was treated after illness day 5 (n ‫؍‬ 146), 137 (93.84%) patients had defervescence within 3 days and 115 (78.77%) had defervescence within 24 hours. One (6.67%) patient in the group that was treated before illness day 5 got a new onset of CAAs, as did 5 (3.85%) in the group that was treated after illness day 5. There was no statistically significant difference in the response rate of IVIG therapy, duration of fever, and incidence of CAAs between these 2 groups. Conclusion.The results of our study indicate that the treatment without aspirin in acute stage of KD had no effect on the response rate of IVIG therapy, duration of fever, or incidence of CAAs when children were treated with high-dose (2 g/kg) IVIG as a single infusion, despite treatment before or after day 5 of illness. We conclude that it seems unnecessary to expose children to high-or medium-dose aspirin therapy in acute KD when the available data show no appreciable benefit in preventing the failure of IVIG therapy, formation of CAAs, or shortening the duration of fever. K awasaki disease (KD) is an acute systemic vasculitis of unknown origin that occurs predominantly in children who are Ͻ5 years old. The most significant complication is coronary arteritis, and an...

A new method based on variance spectroscopy has enabled the determination of absolute absorption cross sections for the first electronic transition of 12 (n,m) structural species of semiconducting single-walled carbon nanotubes (SWCNTs). Spectrally resolved measurements of fluorescence variance in dilute bulk samples provided particle number concentrations of specific SWCNT species. These values were converted to carbon concentrations and correlated with resonant components in the absorbance spectrum to deduce (n,m)-specific absorption cross sections (absorptivities) for nanotubes ranging in diameter from 0.69 to 1.03 nm. The measured cross sections per atom tend to vary inversely with nanotube diameter and are slightly greater for structures of mod 1 type than for mod 2. Directly measured and extrapolated values are now available to support quantitative analysis of SWCNT samples through absorption spectroscopy.

Hydrogenated amorphous silicon nitride (a-SiNx:H) films have been fabricated by plasma-enhanced chemical vapor deposition at temperatures ranging from 50 to 250 °C. It is found that as soon as the samples are taken out from the reaction chamber and exposed to the atmosphere, the a-SiNx:H films start to oxide. The oxidation processes are monitored using infrared absorption spectroscopy. A model of porous ‘‘fractal-like network’’ structure, which is probably inherent in low-temperature deposition, is proposed to explain why moisture (H2O) in the air can percolate through numerous microvoids into these films. The H2O molecules which percolate into these porous films are active to react with the —Si—N—Si—, —Si—N—H, and —N—Si—-H bonds and to form more chemically stabilized —Si—O—Si—, —Si—O—H, and H—O—H bond configurations with the result of eventual oxidization of the entire nitride films.