Temperature dependent hyperfine distributions in Fe-B and Fe-Ni-Si-B glasses

Mössbauer spectra of amorphous Fe_xNi_{80- x} Si₁₀B₁₀ (x=10,50) and Fe₈₀B₂₀ have been taken at 4.2-300K and in 0-6T applied magnetic fields. Detailed analysis shows that the standard deviation of the magnetic hyperfine field σ(B) varies with temperature depending on the iron concentration. For small x the variation is taken as evidence for a break-down of long-range magnetic order. Temperature induced changes in the fluctuations and correlations of the hyperfine parameters are reported. In all cases the isomer shift fluctuations are small compared to those of the first-order electric quadrupole splitting (u); neither are strongly temperature dependent. The correlation <ΔBΔu> is negative and increases with temperature. For Fe₈₀B₂₀, <ΔBΔδ> is positive and increases with temperature, whereas for Fe-Ni-Si-B it is small, negative, and temperature invariant.     

Determination of iodine value fatty acids by a flow-injection method

An automated method for determining the iodine value for various industrial fatty acids is described. The method is based on flow-injection techniques and the chemistry is a modified version of the standard Wij's solution method. The system is fully computerized with an AIM-65 microcomputer. Two detection system, u.v.-visible absorbance and potentiometric sensing, are compared. Results comparable to the conventional method are obtained. Continuous-run sample throughput rates of 12 h^?1 are eralistic.     

On the Mössbauer spectrum of γ-Fe2O3

High quality Mössbauer spectra of γ-Fe₂O₃ particles have been analyzed in detail to determine the effects of overlapping patterns, quadrupole splitting, and applied magnetic fields. The results are discussed with regard to the use of Mössbauer spectroscopy to measure particle and magnetic moment orientation. Data were collected from two samples at 4.2–315K and with 6.1T longitudinal and 1.65T transverse magnetic fields applied. It is shown that electric field gradient effects alone are insufficient to account for the presence of Δm_I=0 lines when a large longitudinal field is applied.     

Some new heterocyclic compounds as analytical reagents

A survey of the metal-complexing reactions, as determined by reactions on chromatography paper, of 44 compounds with a substituted or modified 4-(2-pyridylazo)-resorcinol (PAR) or 1-(2-pyridylazo)-2-naphthol (PAN) structure is reported.     

The sensitivity of some chromatographic sprays

The limits of identification of twenty six common cations, with a selected number of spray reagents used in paper chromatography, have been determined. A table of the most sensitive tests is given.     

On not storing the path of a random walk

We describe a novel form of Monte Carlo method with which to study self-avoiding random walks; we do not (in any sense) store the path of the walk being considered. As we show, the problem is related to that of devising a random-number generator which can produce itsnth number on request, without running through its sequence up to this point.