Synergetic extraction of platinum(IV) from dilute hydrochloric acid by isoamyl alcohol — Methylisobutylketone mixture

A synergetic extraction system isoamyl alcohol-methylisobutylketone for the quantitative separation of platinum as a matrix component from the attending microimpurities is developed. The influence of the different factors on the extraction efficiency is studied. At optimum conditions, the platinum extraction is over 99%; Al, Ca, Mg, Mn, Ni, Cr are quantitatively retained in the aqueous phase. Cu and Pb are partially extracted but the distribution coefficients are constant, independent of the metals concentration. Investigations are made to explain the synergetic extraction mechanism. This method is recommended for the concentration of microimpurity elements in the analysis of pure platinum.     

Integrity of endothelium in cryopreserved human cornea

The aim of the present study was to elaborate an optimal method for cryopreservation of human donor cornea for transplantation and to follow the morphological changes in the structure of the endothelial cell layer using scanning electron microscopy (SEM). Sixteen groups, with four donor cornea each, were cryopreserved at cooling rates of 1 degree C per min and 5 degree C per min. Four cryoprotectants (glycerol, dimethyl sulfoxide, 1,2-propanediol, polyethylene glycol-400) in two concentrations (5% and 10% v/v) were prepared on the bases of medium Optisol GS supplied with 20% v/v human serum albumin. Four additional human cornea were used as controls. Endothelial cell recovery of the cornea after thawing and 24 hours culture, was calculated as a percent of the preserved recovered cells. Sufficient recovery of the endothelial cell layer, making the cornea suitable for transplantation was obtained using the cryoprotectants dimethyl sulfoxide and especially polyethylene glycol-400.     

A device for pulse investigation of heterogeneous catalytic reactions

In the present work a simple device is described for the pulse investigation of heterogeneous catalytic reactions and catalysts. Owing to the possibility for separate adjustment of the gas flow rate in the catalytic reactor and in the chromatographic column, it can be used for kinetic measurements too.

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