Binary nucleation rates for ethanol/water mixtures in supersonic Laval nozzles: analyses by the first and second nucleation theorems.

We performed pressure trace measurements and small angle x-ray scattering measurements to determine the vapor-liquid nucleation rates of EtOH/H2O mixtures including pure EtOH and pure H2O in two supersonic Laval nozzles with different expansion rates. The nucleation rates varied from 0.9 × 10(17) to 16 × 10(17) cm(-3) s(-1) over the temperature range of 210 K to 230 K, EtOH activity range of 0 to 11.

Freezing water in no-man's land.

We report homogeneous ice nucleation rates between 202 K and 215 K, thereby reducing the measurement gap that previously existed between 203 K and 228 K. These temperatures are significantly below the homogenous freezing limit, T(H)≈ 235 K for bulk water, and well within no-man's land. The ice nucleation rates are determined by characterizing nanodroplets with radii between 3.

Methanol nucleation in a supersonic nozzle.

We determined the partial pressures p(Jmax), temperatures T(Jmax), monomer supersaturations S(Jmax), and characteristic times Δt(Jmax ) corresponding to the maximum nucleation rates of methanol in a supersonic nozzle. We found that T(Jmax) increased from 202.2 K to 223.

Monomer, clusters, liquid: an integrated spectroscopic study of methanol condensation.

We have combined static pressure, spectroscopic temperature, Fourier transform infrared spectroscopy (FTIR), and small angle X-ray scattering (SAXS) measurements to develop a detailed picture of methanol condensing from a dilute vapor-carrier gas mixture under the highly supersaturated conditions present in a supersonic nozzle. In our experiments, methanol condensation can be divided into three stages as the gas mixture expands in the nozzle. In the first stage, as the temperature decreases rapidly, small methanol n-mers (clusters) form, increase in concentration, and evolve in size.

Binary nucleation rates for ethanol/water mixtures in supersonic Laval nozzles.

Although the conditions corresponding to the onset of condensation of aqueous-alcohol mixtures have been measured in supersonic nozzles [B. E. Wyslouzil et al.

CH(3)CH(2)OD/D(2)O binary condensation in a supersonic Laval nozzle: Presence of small clusters inferred from a macroscopic energy balance.

We determined the heat released in the condensing flow of a CH(3)CH(2)OD/D(2)O/carrier gas mixture (EtOD/D(2)O for brevity) through a supersonic Laval nozzle by integrating the equations for supersonic flow with condensation, using the static pressure, temperature, and mole fractions of EtOD and D(2)O monomers [S. Tanimura, B. E.

Homogeneous nucleation of a homologous series of n-alkanes (C(i)H(2i+2), i=7-10) in a supersonic nozzle.

Homogeneous nucleation rates of the n-alkanes (C(i)H(2i+2); i=7-10) were determined by combining information from pressure trace measurements and small angle x-ray scattering (SAXS) experiments in a supersonic Laval nozzle. The condensible vapor pressure p(J max), the temperature T(J max), the characteristic time Deltat(J max), and supersaturation S(J max) corresponding to the peak nucleation rate J(max) were determined during the pressure trace measurements. These measurements also served as the basis for the subsequent SAXS experiments.

Nosocomial bacteremia caused by biofilm-forming Bacillus cereus and Bacillus thuringiensis.

Objective: Bacterial biofilms cause serious problems, such as antibiotic resistance and medical device-related infections. Recent reports indicate that Bacillus species potentially form biofilms and cause nosocomial bacteremia via catheter infection. Our objective was to investigate the relationship between nosocomial bacteremia caused by Bacillus species and biofilm formations.

Tunable diode laser absorption spectroscopy study of CH(3)CH(2)ODD(2)O binary condensation in a supersonic Laval nozzle.

We have developed a dual-beam tunable diode laser absorption spectroscopy system to follow the cocondensation of water and ethanol in a supersonic Laval nozzle. We determine the D(2)O monomer concentration in the vapor phase by fitting a Voigt profile to the measured line shape but had to develop a calibration scheme to evaluate the C(2)H(5)OD monomer concentration. To measure the temperature of the gas, we seed the flow with CH(4) and measure two absorption lines with different lower state energies.

Temperature and gas-phase composition measurements in supersonic flows using tunable diode laser absorption spectroscopy: the effect of condensation on the boundary-layer thickness.

We used a tunable diode laser absorption spectrometer and a static-pressure probe to follow changes in temperature, vapor-phase concentration of D2O, and static pressure during condensation in a supersonic nozzle. Using the measured static-pressure ratio p/p0 and the mass fraction of the condensate g as inputs to the diabatic flow equations, we determined the area ratio (A/A*)wet and the corresponding centerline temperature of the flow during condensation. From (A/A*)wet we determined the boundary-layer displacement thickness during condensation (delta#)wet.

Spatially resolved gas phase composition measurements in supersonic flows using tunable diode laser absorption spectroscopy.

We used a tunable diode laser absorption spectrometer to follow the condensation of D(2)O in a supersonic Laval nozzle. We measured both the concentration of the condensible vapor and the spectroscopic temperature as a function of position and compared the results to those inferred from static pressure measurements. Upstream and in the early stages of condensation, the quantitative agreement between the different experimental techniques is good.