Dy 3+ - and Tm3+-doped lanthanum chloride was prepared via reactive atmosphere processing (RAP) of sol-gel derived hydroxide powders. The low-phonon energy chloride host facilitated the 1.3-μm emission from Dy3+ and the 1.2- and 1.4-μm emissions from Tm3+. The emission intensities of the Dy3+ and Tm3+ ions increased logarithmically with increasing RAP temperature. The dependence of emission intensities and lifetimes on the rare-earth (RE) concentration was also investigated. The emission intensity was found to increase up to 1 mole % RE for both ions. Luminescence quenching was observed for concentrations exceeding 1 mole % for Tm3+ and 0.1 mole % for Dy3+.
Summary A specimen of coffee oil has been examined with the objective of determining its composition in the light of possible uses of the oil which is recoverable as a byproduct in the soluble coffee industry. The oil, as obtained by extraction of the coffee grounds with solvent, contains over 5% of unique unsaponifiable material which, without preliminary removal, makes the oil unsuitable for many purposes. It has been shown that the unsaponifiable and glyceridic components can be separated by molecular distillation. A specimen of the methyl esters of the fatty acids of the oil was examined by the ester distillation fractional crystallization techniques. The composition of the component fatty acids has been calculated. The oil contains 46% of linoleic acid. Saturated and unsaturated acids of the C20, C22, and C24 series are present in coffee oil in small amounts.
Summary A number of highly purified fatty acids have been prepared and their solubilities determined in six common organic solvents within the temperature range from 10° to −70°. The acids studied were palmitic, stearic, oleic, elaidic, petroselinic, petroselaidic, linoleic, stearolic, arachidic, eicosenoic, behenic, erucic, and brassidic. The solvents used were methanol, ethyl acetate, diethyl ether, acetone, toluene, and n‐heptane, representing six different solvent types. A limited study was also made with a series of hydrocarbon solvents in order to note any effects of solvent structure on fatty acid solubility. Data are discussed with respect to their application in separating various fatty acid mixtures by low temperature crystallization.
The two-stage Kober reaction with oestriol, oestrone and oestradiol-17\g=b\ has been investigated. The factors involved in the maximum production of colour are summarized.Reducing agents were important in both the first and second stages of the Kober reaction. Oestriol in small amounts did not form the red Kober colour when reducing agents were not present in the first stage.In the absence of water, sulphuric acid did not give optimal results in the first stage. Oestradiol-17\g=b\ failed to give the Kober colour reaction in the presence of high concentrations of sulphuric acid. Optimal sulphuric acid-water ratios differed for the three oestrogens and were 76 % sulphuric acid for oestriol, 66 % acid for oestrone and 60 % acid for oestradiol-17\g=b\. The development of fluorescence was similarly affected by sulphuric acid concentration.The phenol-sulphuric acid reagent used by many workers appears to owe its efficacy to the action of the phenol, partly as a reducing agent and partly as a diluent of the sulphuric acid.Oestriol reacted in the first stage at a slower rate than oestrone and oestradiol.Further water and heating was usually required after the first stage (i.e. for the second stage of the Kober reaction) for complete formation of the red colour. Maximum intensity and stability of the red colour in the second stage was obtained in the presence of 50-60 % sulphuric acid and water. Under these optimum conditions the second heating time was not critical.In the second stage, concentrations of sulphuric acid lower than 50 % caused instability of the colour and fading during heating.In the second stage of the Kober reaction, reducing agents with oxidation-reduction potentials of the order of the hydroquinone-quinhydrone couple were also required for the production of maximum density and stability of the red colour.A colour method based on these findings is presented.Marrian [1930] reported that when oestriol was warmed with concentrated sulphuric acid, an orange colour with a green fluorescence was produced. Kober [1931] noted that when this orange fluorescent solution was diluted with water and warmed, the colour changed to a clear red, also with a greenish fluorescence, and that this change appeared to be almost specific for the natural oestrogens. Phenol added to the reaction mixture quenched the final fluorescence making the red colour both more intense and suitable for visual colorimetry. This colour reaction is known generally as the Kober reaction, although many modifications have since been proposed. Kober's original method was thus carried out in two stages, the first being the formation of the orange (or under certain conditions, yellow) intensely fluorescing colour and the second the conversion of this to the red colour. The intense greenish fluorescence obtained in the first stage of the Kober colour reaction has been used by a number of workers [Jailer, 1947;, for the fluorimetrie estima¬ tion of the natural oestrogens. These fluorimetrie methods, though not highly specific, are very sensitive and...
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