Spectrophotometric study of uranium(VI) chelate formation with beta-diketones and tributyl phosphate in aqueous, nona(oxyethylene) dodecyl ether solution.
The distribution ratio of uranium(VI) with 2-thenoyltrifluoroacetone, 2-furoyltrifluoroacetone and benzoyltrifluoroacetone in the presence and absence of tributyl phosphate between micellar and bulk phases in nona(oxyethylene) dodecyl ether solution was measured spectrophotometrically as a function of hydrogen-ion concentration. The thermodynamic constants for these reactions were evaluated from the variation of the equilibrium constants as a function of temperature. The entropy change contributes to the synergistic reaction.
Temperature effect on the synergistic solvent extraction of some lanthanides with mixtures of 1-phenyl-3-methyl-4-benzoyl-pyrazol-5-one and Aliquat 336
Abstract The temperature effect on the synergistic solvent extraction of Pr, Gd and Yb with mixtures of 1-phenyl-3-methyl-4-benzoyl-pyrazol-5-one and the quaternary ammonium salt Aliquat 336 has been studied. The values of the equilibrium constants and other thermodynamic parameters have been calculated. Some considerations has been given to the extraction mechanism.
Hedy: A Gradual Language for Programming Education
One of the aspects of programming that learners often struggle with is the syntax of programming languages: remembering the right commands to use and combining those into a working program. Prior research demonstrated that students submit source code with syntax errors in 73% of cases and even the best students do so in 50% of cases. An analysis of 37 million compilations by 250.000 students found that the most common error was a syntax error, which occurred in almost 800.000 compilations. It was also found that Java and Perl are not easier to understand than a programming language with randomly generated keywords, stressing the difficulties that novices face in understanding syntax. This paper presents Hedy: a new way of teaching the syntax of a programming language to novices, inspired by educational methods by which punctuation is taught to children. Hedy starts as a simple programming language without any syntactic elements such as brackets, colons or indentation. The rules slowly and gradually change until the novices are programming in Python. Hedy is evaluated on 9714 programs.