High resolution study of the reactions 54, 56, 58Fe(16O, 12C)58, 60, 62Ni and a comparison with (6Li,d) α-transfer spectroscopy

Spectra and angular distributions for the reactions ^{54, 56, 58}Fe(¹⁶O, ¹²C)^{58, 60, 62}Ni (E_x = 0.0–4.5 MeV) have been measured at 50 MeV with an energy resolution of 45–80 keV using a Q3D spectrograph. The selectivity of the (¹⁶O, ¹²C) reaction is found to be very similar to the (⁶Li, d) reaction. The close correspondence recently noted between the (⁶Li, d) spectra and levels strongly excited in (t, p) and (³He, n) two-nucleon transfer reactions is also observed to be present for the (¹⁶O, ¹²C) reaction. Relative α spectroscopic factors for (¹⁶O, ¹²C) and (⁶Li, d) obtained in a DWBA analysis assuming direct one-step α-cluster transfer are in very good quantitative agreement. Unnatural parity states, whose excitation is forbidden in the DWBA α-cluster approximation, are observed to be very weakly populated. These results, together with previous work on s-d shell and Ni targets, strongly suggest that the spectroscopic information provided by the (¹⁶O, ¹²C) and (⁶Li, d) reactions is essentially the same and that this information may be reliably extracted by DWBA analysis.     

Small-scale preparative supercritical fluid chromatography of cyproterone acetate

Summary A method for the micropreparative fractionation of steroid hormones from process solutions was developed. Using a commercial SFC equipment and raw cyproterone acetate (CPA) as a model sample, we showed the value of SFC as a lab scale purification method and also its potential as an environmentally friendly approach to preparative scale chromatography.     

Steric effects in the tetracyanoethylene catalysed methanolysis of some cyclohexane epoxides

The presence of a hydroxyl group has been shown to direct the regiochemistry and stereochemistry of the TCNE methanolysis of cyclohexane hydroxy-epoxides. α-Pinene epoxide underwent cleavage to form the 8-methyl ether of trans-sobrerol.     

Surface dependence of field ion energy distributions,He on W

Kinetic energy distributions of helium ions produced by field ionization above the (100), (110), and (111) planes of tungsten field emitters are reported. The energy resolution of these measurements if 0.3 eV fwhm. The main peak of these distributions is found to shift by as much as 0.7 eV at $\text{F = 5.3 V/}\text{A}\text{?}$, T = 21 K, when the origin of the ions collected is changed slightly. Several possible explanations for this shift are discussed. The most plausible of these involves electron tunneling through a field adsorbed helium atom. These results have important implications for the use of field ion energy distributions as a probe of the density of electronic states of the emitter.     

Particle ratios in inclusive electroproduction from hydrogen and deuterium

We present a high statistics study of particle ratios in electroproduction of forward hadrons. The π⁺/π^? ratios for a proton target rise monotonically to a value of 2.4 ± 0.2 at Q² of 3 (GeV/c)² and for a neutron target average 1.16 ± 0.04 from Q² of 0.35 to 3 (GeV/c)². We report the first data on electroproduction of $\text{p}$, and measure the cross sections of K^±, p, and $\text{p}$ relative to pions as a function of Q².     

Phosphorescence excitation spectra of methylbenzaldehydes in durene single crystals: Site structure and effects of deuterium substition

The low-temperature (15 K) laser phosphorescene excitation spectra of 2,4,5-trimethylbenzaldehyde-1h₁ and -1d₁, and 2,5-dimethylbenzaldehyde-1h₁ and -1d₁, each isolated in durene single crystals are presented. Spectra of molecules in each of two different durene crystal sites were obtained. The red shift of the T₁(0.0) bands upon deuteration, is consistent with these bands arising from φφ1 excitations. The red shift of the TMB T₂(0.0) and the blue shift of the DMB T₂(0.0) may reflect the differing electronic configurations of these states (φφ1 or nφ1 respectively) or may be determined by the details of the coupling of T₂ to the underlying T₁ vibronic levels. A broad continuum-like features was observed in the region of T₂. Changes in this feature brought about by deuteration or a change in crystal environment suggest the involvement of both vibronic and crystal-field-induced coupling of T₂ to the underlying T₁ vibronic levels     

Instantaneous three-dimensional flow visualization of a supersonic mixing layer

An imaging technique capable of time-resolved, three-dimensional visualizations of compressible flows is described and applied to a supersonic mixing layer. The three-dimensional planar imaging system uses a custom high-speed camera to acquire 10 successive planar images through the mixing layer at a rate of 10⁷ frames per second. Mixed fluid in the layer is visualized by Mie scattering of a laser light sheet from condensed alcohol droplets. After collection, the planar images are corrected for distortions and stacked to form data volumes. Comparative visualizations at low and moderate convective Mach numbers (M _c = 0.43 and 0.62) are used to examine the effects of compressibility on large-scale structure in mixing layers. The visualizations graphically reveal the shift from two-dimensional spanwise rollers to three-dimensional structure, such as oblique and V-shaped bands, with increasing compressibility. Additionally, direct comparison between the high- and low-speed edges of the mixing layer shows the high-speed interface to be smoother than its lowspeed counterpart.The authors would like to acknowledge Dr. Michael Miller and Dr. Jerry Seitzman for many helpful discussions, and William Urban for assistance in performing the experiments. This work is supported by the Air Force Office of Scientific Research, Aerospace Sciences Directorate, J. Tishkoff technical monitor.