Structural and electronic properties of CuInSe2

Structural investigation on monocrystalline CuInSe₂ samples has been made. From the single crystal results, the space group of CuInSe₂ was confirmed to be Iˉ42d and the crystal solidification direction was investigated. Compositional uniformity of the ingots was established by EPMA and it was found that the indium concentration was greater than that for copper. Systematic annealing experiments were carried out in vacuum at different temperatures (as low as 160° C) and for different times. Large variation in resistivity was observed after the annealing treatment. P-type samples were found to convert to n-type after the heat-treatments.     

Suggestions for the quantitative X-ray microanalysis of thin sections of frozen-dried and embedded biological tissues

When a microregion in a thin section of frozen-dried and embedded tissue is analysed by the conventional electron-probe X-ray continuum-normalization method, the measured quantity is in mmol of element per kg of embedded specimen. As each microregion contains an unknown amount of embedding medium, this quantity generally lies indeterminately somewhere within the wide range between mmol of element per kg of hydrated tissue and mmol of element per kg of dehydrated tissue. However, if a ‘tag’ element is incorporated in the embedding medium, the contribution of the medium to the local continuum count in each probed field should be measurable, and the X-ray data may then unambiguously yield mmol of element per kg of dehydrated tissue. This result should not be affected by shrinkage on freeze-drying or by incomplete replacement of water by embedding medium. The same X-ray data can additionally provide estimates of mmol of element per unit volume, mmol of element per kg of hydrated tissue and local dry-mass fraction. However, these estimates are subject to errors due to tissue shrinkage, incomplete replacement of water and beam damage.     

Transport of K in PVC matrix membranes containing valinomycin

We report impedance measurements on PVC matrix membranes which contain KBPh₄ with varying proportions of valinomycin. In agreement with our earlier measurements the value of the bulk membrane resistance (R_b) is much larger in the presence of valinomycin, indicating that the mobility of K⁺ is greatly reduced by the valinomycin. R_b shows a linear variation with valinomycin/K⁺ ratio between 0 and 1, but it is invariant at higher valinomycin/K⁺ ratios. Thus there is no evidence for a special transport mechanism for K⁺ in these membranes.     

Drying cellulose triacetate in a dryer with a vibrational fluidized bed

Conclusions The process of drying cellulose triacetate in a vibrating bed has been studied.For final drying of cellulose triacetate before solution, it is recommended to use an industrial specimen of a unit with a vibrating bed having a capacity of 2700 kg/h.This assembly can be used to dry other fibre-forming disperse polymeric materials containing strongly bound moisture.Translated from Khimicheskie Volokna, No. 3, pp. 49–51, May–June, 1984.     

N.m.r. line shape-relaxation correlation analysis of bitumen and oil sands

The first results of the analysis of bitumen and oil sands using the recently developed n.m.r. spingrouping technique are presented. The n.m.r. relaxation experiments were carried out on bitumen, and on natural and dried oil sands samples. The results indicate that the spin-grouping can resolve and quantify several components of the samples studied. The bitumen and bitumen fraction of the oil sands are resolved according to their spin-spin relaxation times into three major groups: solid-like (rigid), solid-like (mobile) and semi-liquid. The water in the oil sands exists in two different environments. Tentatively one environment is assigned to be the bridges between the sand grains, while the other is assigned to be the clay surface. One can conclude that with spin grouping of complex mixtures the decomposition (in which components are resolved according to their dynamic state) is possible. The accuracy of such resolution is of the order of a few per cent.