Thermochemical Investigations in the System Cadmium-Praseodymium Relevant for Pyrometallurgical Fuel Reprocessing

Vapor pressure measurements, in terms of a (non-)isothermal isopiestic method, were carried out in the system Cd-Pr between 749 K and 1067 K (476 °C and 794 °C). Thermodynamic activities of cadmium as a function of temperature were obtained directly for the composition ranging from 50.0 to 85.7 at. pct Cd. From these results, partial molar enthalpies of mixing of Cd were derived for the corresponding composition range. The activity values of Cd were converted to an average sample temperature of 823 K (550 °C) by applying an integrated form of the Gibbs–Helmholtz equation. These data indicate that Cd₂Pr and Cd₅₈Pr₁₃ are probably the most stable intermetallic compounds in this system. Using an activity value of Pr from the literature as integration constant, Gibbs–Duhem integration was performed, and integral Gibbs energies are presented at 823 K (550 °C), referred to Cd(l) and α-Pr(s). Gibbs energies of formation at the stoichiometric compositions of the phases Cd₆Pr, Cd₅₈Pr₁₃, Cd₄₅Pr₁₁, Cd₃Pr, and Cd₂Pr were determined to be about ?18.8, ?23.5, ?24.8, ?28.7, and ?33.8 kJ g-atom^?1 at 823 K (550 °C), respectively.     

Controlled Creating of Cracks in Concrete for Non-destructive Testing

The non-destructive assessment of cracks in concrete is a common task for which non-destructive evaluation solutions have been published. Primarily, these tests have been carried out on artificial cracks that have been created by using notches instead of natural cracks. This study evaluates a procedure designed to create reproducible and controlled cracks in concrete. The procedure is based on using expanding mortar in a series of blind holes. This is done in combination with carefully aligned reinforcement to guide the direction of the crack development. The depth of the crack is also controlled by reinforcement. Crack depth varies statistically in the range of the maximum aggregate size (16 mm) used for concrete.     

Comments on “School Integration Policies in Northern Cities”

This study develops a research method of assessing people's satisfaction with housing. Instead of the old approaches which consider in fragmented ways the characteristics of the dwelling, or the neighborhood, or the social environment, the author proposes a systems approach in which various interdependent factors are studied in relation to one another. Using the techniques developed, the relative satisfaction of tenants in public housing projects in certain areas of Canada is identified, analyzed, and discussed.     

Urban Development the Pattern and the Background; Concluding Discussion

When We Build Again. A Bournville Village Trust Research Publication. George Allen &; Unwin, Ltd., London, 1941. Pp. xii (16), 138.

Report Relative to Postwar Reconstruction in the City, Prepared by Improvements and Town Planning Committee, published by The Corporation of London, 1944, pp. 66 plus maps and photographs.

The Economic Status of the New York Metropolitan Region in 1944, by The Regional Plan Association, Inc., New York, 1944, xx, 91 pp.     

Processing of CaLa2S4 infrared transparent ceramics: A comparative study of HP and FAST/SPS techniques

The densification of CaLa₂S₄ (CLS) powders prepared by combustion method was investigated by the use of Field-Assisted Sintering Technique (FAST) and Hot Pressing (HP). CLS powders were sintered using FAST at 1000°C at different pressures and heating rates and sintered by HP under 120 MPa from 800°C to 1100°C for 6 hours with a heating rate of 10°C/min. Comparison of both techniques was further realized by use of the same conditions of pressure, dwell time, and heating rate. Complementary techniques (XRD, SEM-EDS, density measurements, FTIR spectroscopy) were employed to correlate the sintering processes/parameters to the microstructural/compositional developments and optical transmission of the ceramics. Both sintering techniques produce ceramics with submicrometer grain size and relative density of about 99%. Nevertheless, HP is more suitable to densify CLS ceramics without fragmentation and also reach higher transmission than FAST. Transmission of 40%–45% was measured out of a possible maximum of 69% based on the Fresnel losses in the 8-14 μm window when HP is applied at 1000°C for 6 hours under 120 MPa. In both techniques, ceramics undergo reduction issues that originate from graphitic sintering atmosphere.     

Synthese von Benzo[b]thioxanthenen

Synthesis of Benzo[b]thioxanthenes Benzo[b]thioxanthenes, heterocyclic compounds related to tetracenes and tetracyclines can be obtained by the reaction of 2H-benzo[b]thiete ( 1 ) and 1,4-naphthoquinones ( 3a–g ). The primary cycloadducts 4a–g undergo an autoxidation process leading to the quinones 6a–g . The dihydroxy compound 4e shows an additional isomerization by a tetrafold H transfer ( 4e → 5e ′). Another preparative route to benzo[b]thioxanthenes makes use of the cycloadditon reaction of 1 and 1,4-epoxynaphthalenes ( 7a–d ). The primary adducts can be transformed to the title compounds by catalytic dehydration processes ( 8a–d → 9a-d ). An alternate regioselective opening of the oxygen bridge can be performed by the action of trimethyliodosilane ( 8a → 10a ). Methylation of 9a furnishes the sulfonium salt 14a which rearranges in a strongly alkaline medium to 16a ; in the presence of oxygen ketone 17a is generated.