Efficient Nanosecond Photoluminescence from Infrared PbS Quantum Dots Coupled to Plasmonic Nanoantennas

Infrared (IR) light sources with high modulation rates are critical components for on-chip optical communications. Lead-based colloidal quantum dots are promising nonepitaxial materials for use in IR light-emitting diodes, but their slow photoluminescence lifetime is a serious limitation. Here we demonstrate coupling of PbS quantum dots to colloidal plasmonic nanoantennas based on film-coupled metal nanocubes, resulting in a dramatic 1300-fold reduction in the emission lifetime from the microsecond to the nanosecond regime. This lifetime reduction is primarily due to a 1100-fold increase in the radiative decay rate owing to the high quantum yield (65%) of the antenna. The short emission lifetime is accompanied by high antenna quantum efficiency and directionality. This nonepitaxial platform points toward GHz frequency, electrically modulated, telecommunication wavelength light-emitting diodes and single-photon sources.United States. Dept. of Energy. Center for Excitonics (Award DE-SC0001088

The ionization produced in nuclear emulsion by very relativistic particles

In order to determine the shape of the ionization curve in nuclear emulsions at values of ϒ˃100, we have measured the blob density of relativistic electron tracks. The pv of the pair produced electrons used was determined by multiple scattering. A total of 84.45 centimeters of electron track was blob taunted and scattered. From ϒ = 100 to ϒ = 5400 the data were combined into 14 points each with a statistical uncertainty on blob density of less than 1%. These points indicate a level "plateau" and show no deviation from this plateau within our statistical accuracy. Pions were used to estimate the minimum of the ionization curve 5 and ratio of blob density plateau to blob density minimum is estimated to be 1.140 ± .020.http://www.archive.org/details/ionizationproduc00hansLieutenant, United States Coast GuardLieutenant, United States NavyLieutenant, United States Nav

Evaluation of a Multidrug Assay for Monitoring Adherence to a Regimen for HIV Preexposure Prophylaxis in a Clinical Study, HIV Prevention Trials Network 073

ABSTRACT Daily oral tenofovir disoproxil fumarate (TDF)-emtricitabine (FTC) is a safe and effective intervention for HIV preexposure prophylaxis (PrEP). We evaluated the performance of a qualitative assay that detects 20 antiretroviral (ARV) drugs (multidrug assay) in assessing recent PrEP exposure (detection limit, 2 to 20 ng/ml). Samples were obtained from 216 Black men who have sex with men (208 HIV-uninfected men and 8 seroconverters) who were enrolled in a study in the United States evaluating the acceptability of TDF-FTC PrEP (165 of the uninfected men and 5 of the seroconverters accepted PrEP). Samples from 163 of the 165 HIV-uninfected men who accepted PrEP and samples from all 8 seroconverters were also tested for tenofovir (TFV) and FTC using a quantitative assay (detection limit for both drugs, 0.31 ng/ml). HIV drug resistance was assessed in seroconverter samples. The multidrug assay detected TFV and/or FTC in 3 (1.4%) of the 208 uninfected men at enrollment, 84 (40.4%) of the 208 uninfected men at the last study visit, and 1 (12.5%) of the 8 seroconverters. No other ARV drugs were detected. The quantitative assay confirmed all positive results from the multidrug assay and detected TFV and/or FTC in 9 additional samples (TFV range, 0.65 to 16.5 ng/ml; FTC range, 0.33 to 14.6 ng/ml). Resistance mutations were detected in 4 of the 8 seroconverter samples. The multidrug assay had 100% sensitivity and specificity for detecting TFV and FTC at drug concentrations consistent with daily PrEP use. The quantitative assay detected TFV and FTC at lower levels, which also might have provided protection against HIV infection

ISOLATED HYPOPLASIA OF THE RIGHT VENTRICLE AND TRICUSPID VALVE IN SIBLINGS

This paper describes the clinical and morbid anatomical findings in two siblings having hypoplasia of the right ventricle and tricuspid valve without other cardiac defects, and it discusses the possible hemodynamic consequences and differential diagnosis of this malformation. Hypoplasia of the right ventricular chamber is seen in tricuspid atresia (Taussig, 1947) and in some cases of pulmonary atresia with intact ventricular septum, and it may be associated with tricuspid hypoplasia in the latter condition (Chiche, 1952). Apparently however, there have been no previous descriptions of isolated hypoplasia of the right ventricle and tricuspid valve, although Keith et al. (1958) list this combination as one that can be mistaken for tricuspid atresia. It is convenient to distinguish pathologically congenital tricuspid stenosis, in which the orifice is narrow because of failure of commissural separation, from tricuspid hypoplasia, in which the orifice is reduced by the small size of the valvular ring but the small valvular leaflets are otherwise essentially normal. In our cases the right ventricular hypoplasia consisted in abnormally small external size, wall thickness, and chamber capacity. REPORT OF CASES Clinical Observations. Case 1.-The patient, a girl, was born in August, 1954. Her mother had had on