Electromagnetic radiation originating from unstable electron oscillations

Electromagnetic oscillations in the range 300 – 700 MHz were observed from an unmagnetized argon discharge with an unstable electron velocity distribution function.     

Ion-beam-excited electrostatic ion cyclotron waves

Self-excited electrostatic ion cyclotron waves were observed in an ion-beam-plasma system produced in a DP-operated Q-machine. The frequency of the waves showed the theoretically predicted variation with the magnetic field.     

A derivation of local composition expressions from partition functions

This paper presents a method for developing local composition expressions from partition functions and the two-liquid theory. The assumptions required for the derivation are discussed. It is shown that the local composition expressions are theoretically founded only in the vicinity of complete randomness.     

Spin-canting and transverse relaxation in maghemite nanoparticles and in tin-doped maghemite

The magnetic properties of maghemite nanoparticles and tin-doped maghemite have been studied by ⁵⁷Fe and ¹¹⁹Sn Mössbauer spectroscopy at temperatures from 6 to 300 K with and without applied magnetic fields. The low-temperature ⁵⁷Fe spectra of both samples, obtained in a field of 4 T, can be described in terms of A-site and B-site components with perfect ferrimagnetic order and a strongly canted component, which seems to have its main contribution from B-site ions. At higher temperatures, the components with strong canting are influenced by transverse relaxation, which results in significant line broadening, a reduction of the magnetic hyperfine splitting and a reduction in the relative areas of lines 2 and 5. The ¹¹⁹Sn spectra show a very broad distribution of magnetic hyperfine fields at low temperatures. When the sample was exposed to applied magnetic fields the distribution became narrower. The spectra show that the direction of the hyperfine field of a large fraction of the tin ions in maghemite is antiparallel to the applied field, but a minor fraction of the tin ions have canted hyperfine fields.     

H Chemical Shielding Anisotropies from Polycrystalline Powders Using MSHOT-3 Based CRAMPS

It is demonstrated that combined rotation and multiple-pulse spectroscopy (CRAMPS) based on MSHOT-3 homonuclear multiple-pulse decoupling represents a powerful method for determination of¹H chemical shielding anisotropies from polycrystalline powders. By virtue of high-order dipolar decoupling, large spectral width, resonance offset stability, and the absence of artifacts fromtilted-axis precession, MSHOT-3-based CRAMPS enables straightforward sampling of high-quality spectra. Comparison with explicit calculations, taking the effect of the multiple-pulse sequence into account, shows that the spectra may be simulated and iteratively fitted using standard software for the calculation of magic-angle spinning spectra influenced by chemical shielding anisotropy with the shielding interaction reduced by the scaling factor of the MSHOT-3 decoupling sequence. The method is demonstrated by experimental determination of¹H chemical shielding anisotropies for adipic acid, Ca(OH)₂, malonic acid, and KHSO₄. The data are compared with those determined previously from single-crystal NMR studies.     

Prediction of Separation Factors Using Group Contribution Methods a Review

For separation process design calculations such as distillation, absorption and extraction it is unconditionally necessary to have quantitative information on the mixtures in consideration, i.e. knowledge about phase equilibrium compositions, heats of mixing etc.     

Infrared Spectra of Tris(ethylendiamine) Cobalt(III) Complex Ion in Solid State and Dissolved in Light and Heavy Water

In recent years, at least two groups^1,2 have developed programmes for combined conformational and vibrational analysis of complicated molecular systems. A version of one of these systems² is currently being adapted for work on coordination complexes. In such work experimental data are needed, and they stem almost exclusively from x-ray structural determinations, and infrared spectra of solids. Most calculational schemes so far deal with isolated molecules, and as one objective of the calculations is to provide thermodynamic functions, which, as far as coordination complexes are concerned, are measured in aqueous solution, we consider it necessary to compare some key properties of the substances as measured in the solid state and in solution. In particular, we want to investi- gate the extent to which internal vibrations are independent of the surroundings of the complexion.     

Profiling of impurities in illicit amphetamine samples by high-performance liquid chromatography using column switching

A simple high-performance liquid chromatographic method, suitable for routine profiling of impurities in illegally produced amphetamine, has been developed. Amphetamine is dissolved in acetonitrile-citrate buffer (pH 3) (2:8) and injected directly without further sample pre-treatment. The impurities are enriched on-line on a C8 extraction column, while amphetamine and polar diluents are washed out with water. After washing for 1.5 min, a six-port valve is switched and an acetonitrile-0.2 M butylamine in water (pH 8) gradient elutes the impurities from the extraction column on to a C18 analytical column where they are separated. The compounds are monitored by UV detection at 220 and 254 nm. The total extraction and analysis time is 30 min. The method allows automated extraction and analysis to be performed.     

Nuclear rotational population patterns in heavy-ion scattering and transfer reactions

A model of²³⁹Pu with decoupled neutron is used for theoretical calculations of rotational population patterns in heavy ion inelastic scattering and one-neutron transfer reactions. The system treated is⁹⁰Zr on²³⁹Pu at the near-barrier energy of 500 MeV and backscattering angles of 180° and 140°. The influence of the complex nuclear optical potential is seen to be very strong, and the Nilsson wave function of the odd neutron produces a distinctive pattern in the transfer reaction.