Optimization of a high speed countercurrent chromatograph for analytical separations

The analytical capability of the high speed countercurrent chromatograph model 4000 (HSCCC-4000) has been improved by optimizing the dimensions of the multilayer coiled column. Using a two-phase solvent system of n-hexane – ethyl acetate – methanol – water (1:1:1:1) and a set of indole auxins as test samples, a series of studies was conducted to evaluate performance of coiled columns with i.d.s ranging from 0.1 to 0.55 mm. The studies on the stationary phase retention indicated that multilayer coils of 0.55 mm and 0.30 mm i.d. provide satisfactory retention of the stationary phase while the 0.10 mm i.d. column fails to yield reproducible retention. The best partition efficiencies were obtained from the 0.30 mm i.d. multilayer coil with a 6 ml capacity which produced theoretical plate numbers ranging from 5500 to 10500 with a resolution factor of 2.30. The feasibility of interfacing the HSCCC-4000 with a mass spectrometer is briefly discussed.     

Effect of pressure on the Néel temperature and the lattice parameter of MnTe

The Néel temperature of MnTe has been measured at high pressures up to 70 kbar and found to increase with pressure. The rate of increase changes discontinuously near 40 kbar. The lattice parameters were measured by X-ray diffraction techniques, and also change anomalously near 40 kbar. From these results, it appears that some kind of magnetic phase transition occurs at this point. A magnetic phase diagram is proposed.     

Asymptotic formulas for the hyperġeometric function2 F 1 of matrix argument,useful in multivariate analysis

Summary LetS _i have the Wishart distributionW _p(∑_i,n_i) fori=1,2. An asymptotic expansion of the distribution of for large n=n₁+n₂ is derived, when∑ ₁∑ ₂ ⁻¹ =I+n^−1/2θ, based on an asymptotic solution of the system of partial differential equations for the hypergeometric function₂ F ₁, obtained recently by Muirhead [2]. Another asymptotic formula is also applied to the distributions of −2 log λ and −log|S ₂(S ₁+S ₂)⁻¹| under fixed∑ ₁∑ ₂ ⁻¹ , which gives the earlier results by Nagao [4]. Some useful asymptotic formulas for₁ F ₁ were investigated by Sugiura [7].     

Optimal tests for electroweak loop effects

A statistical analysis is given for the experimental precision necessary for establishing loop effects in the electroweak theory. Cases with three observables, gauge boson masses and the Weinberg angle, is analyzed by an optimised test. An information on the Weinberg angle with even 5% error (±.01 in sin² θ _W ) is shown to reduce the requirement for the measurements of gauge boson masses significantly.     

Measurement of the liquid phase mass in gas-liquid sprays by X-ray attenuation

An optical method for measuring the mass of liquid phase in a spray has been developed into an X-ray method. An X-ray of about 6 keV is used to measure the mass distribution of liquid phase in the spray formed by a concentric injector with water and gaseous nitrogen at one atmosphere of pressure. The possibility of measuring the mass of gaseous oxygen and hydrogen is discussed.     

Benzyne-induced fragmentation of 1,3-oxathiolanes. A novel method for deprotection of carbonyl groups,preparation of phenyl vinyl sulfides,and 1,2-carbonyl transposition

A variety of 1,3-oxathiolanes undergo a benzyne-induced fragmentation leading to phenyl vinyl sulfides and carbonyl compounds. The reaction developed here provides a novel method for deprotection of carbonyl compounds from 1,3-oxathiolanes, preparation of phenyl vinyl sulfides, and 1,2-carbonyl transposition.     

The effect of morphology on sorption and transport of carbon dioxide in poly(4,4'-oxydiphenylene pyromellitimide)

Sorption and transport of carbon dioxide were investigated for poly(4,4'-oxydiphenylene-pyromellitimide) films (PI-1, PI-2, and PI-3) imidized at 160, 200, and 400°C, respectively, as well as for a chemically identical commercial polyimide film, Kapton-H. The solubility, permeability, and diffusion coefficients (S, P, and \[ \overline D \] , respectively) at 80°C and 20 atm in PI-3 were 67, 25, and 37%, respectively, as large as those in PI-2. These significant reductions are attributed to a higher degree of segmental aggregation in PI-3 caused by a 1.7% increase in the density (d) as compared with PI-2. The differences in S, P, \[ \overline D \] , and d between PI-3 and Kapton-H were rather small as compared with those between PI-3 and PI-2, suggesting that the in-plane orientation has a minor effect on the sorption and transport in Kapton-H as compared with the aggregation. Influence of the morphology on the dual-mode sorption and transport parameters was also investigated. With increasing density, the Langmuir capacity constant and the diffusion coefficients for the Henry's law and Langmuir populations decreased by higher rates than the Henry's law solubility constant, being contrary to the results reported for a typical semicrystalline glassy polymer, polyethylene terephthalate. This may suggest that the nonaggregated or less-aggregated regions taking an important part in the sorption and transport are denser for the sample having a higher overall density.