We report homogeneous-nucleation-temperature measurements in liquid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ over a bath-temperature range $2.31<\mathrm{}{T}_b<4.62\mathrm{}$ K. These measurements were performed with the use of a transient superheating technique. The nucleation data constitute a demonstration of the quantitative accuracy of the Becker-Döring nucleation theory in describing the first-order transition kinetics in a quantum liquid, such as liquid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, in a region far from the critical point. A simple empirical form is presented for estimating the homogeneous-nucleation temperatures for any liquid with a spherically symmetric interatomic potential. The ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ data are compared with nucleation data for Ar, Kr, Xe, and ${\mathrm{H}}_2$; theoretical predictions for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ are given in terms of reduced quantities. It is shown that the nucleation data for both quantum and classical liquids obey a quantum law of corresponding states (QCS). On the basis of this QCS analysis, predictions of homogeneous-nucleation temperatures are made for hydrogen isotopes such as HD, DT, HT, and ${\mathrm{T}}_2$.

We investigate the manipulation of 5 nm diamond nanoparticles in a user-defined pattern on a substrate using the acoustic radiation force associated with a bulk acoustic standing wave. Both concentric and rectangular patterns are studied and the experimental results are compared with theoretical predictions. The effect of drag force acting on a nanoparticle is evaluated and limits for particle speed and particle size that can be moved by acoustic radiation force are determined. We found good agreement between our experimental results and existing theoretical models and demonstrate that nanosized particles can be manipulated effectively by means of bulk wave acoustic radiation force.

Funneling-current transients produced in semiconductor devices are predicted to occur on a picosecond time scale. We have measured these transients using a high bandwidth sampling system. Measurements were made on 1, 3, and 10 μ-cm silicon low capacitance diodes and 1016 cm-3 Te-doped GaAs diodes. The data is compared to the Hsieh, Murley and O'Brien, the McLean and Oldham, and the Messenger models. Risetime versus doping density, peak current, total charge, and amplitude versus bias were measured. Also, current transients and prompt charge versus energy are presented.

A new class of devices for levitation and/or concentration of aerosols and small liquid/solid samples (up to several millimeters in diameter) in air has been developed. The novelty of these devices is their simplicity in design. These are inexpensive, low-power, and, in their simplest embodiment, do not require accurate alignment of a resonant cavity. Best of all, these can be off-the-shelf items. The devices are constructed from a hollow, cylindrical piezoelectric tube. The main design criteria requires a resonant mode of the tube to match a resonant mode of the interior air-filled cavity. Once matched, it is shown that drops of water in excess of 1 mm in diameter may be levitated inside the cylinder cavity against the force of gravity for less than 1 Watt of input electrical power. Efficient concentration/agglomeration of aerosol particles in air is also demonstrated.

This paper presents a method of determining the volume fractions of two liquid components in a two-phase flow by measuring the speed of sound through the composite fluid and the instantaneous temperature. Two separate algorithms are developed, based on earlier modeling work by Urick (Urick, 1947, “A Sound Velocity Method for Determining the Compressibility of Finely Divided Substances,” J. Appl. Phys., 18 (11), pp. 983–987) and Kuster and Toksöz (Kuster and Toksöz, 1974, “Velocity and Attenuation of Seismic Waves in Two-Phase Media: Part 1. Theoretical Formulations,” Geophysics, 39 (5), pp. 587–606). The main difference between these two models is the representation of the composite density as a function of the individual densities; the former uses a linear rule-of-mixtures approach, while the latter uses a nonlinear fractional formulation. Both approaches lead to a quadratic equation, the root of which yields the volume fraction ($φ$) of one component, subject to the condition $0≤φ≤1$. We present results of a study with mixtures of crude oil and process water, and a comparison of our results with a Coriolis meter. The liquid densities and sound speeds are calibrated at various temperatures for each fluid component, and the coefficients are used in the final algorithm. Numerical studies of sensitivity of the calculated volume fraction to temperature changes are also presented.