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Abstract  

Paleozoic black shales of the Saxothuringikum (Germany) with an average Corg. -content of 0.01 to 20 mass% were investigated with regard to the nature of organic matter. A special pyrolysis technique (DEGAS) was used for a temperature resolved analysis of different hydrocarbons (HC) and the simultaneous detection of inorganic volatiles during heating under vacuum up to 1450C. The presented data indicate three different forms of organic matter occurring in the investigated black shales (bitumen, kerogen and pyrobitumen). Finally the influence of an igneous dyke intrusion on the alteration of the organic matter was examined.

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Abstract  

A modified procedure using thin layer chromatography is described to determine the specific activity of carrier-free radioactive NaI solutions. It gives more accurate results and can be performed within a short time.

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Abstract  

The aim of this paper is to determine temperature and structural changes caused by tableting and to deduce from the combination of temperature measurement and the determination of structural changes whether temperature increase induced by tableting contributes to tablet quality. Tablets were produced of microcrystalline cellulose (MCC), spray-dried lactose, pregelatinized starch, and dicalcium phosphate dihydrate (DCPD) with an instrumented single punch tableting machine. The temperature pattern at the surface of the tablets was measured starting directly after tableting with an infrared thermoviewer and an infrared sensor. Powder and tablets were analyzed by FT-Raman spectroscopy, the tablets were analyzed directly after tableting and after one month of storage. The crushing force of the resulting tablets was determined. For all materials a temperature increase (TI) induced by tableting was determined with both methods used. The order of the temperature increase was the same for both methods used: TI (MCC)>TI (spray-dried lactose)>TI (pregelatinized starch)>TI (DCPD). The order was also identical for the crushing force of the tablets. The extent of differences in the spectra followed the same ranking. In conclusion, the temperature increase contributed to the changes in material structure and thus temperature increase is one factor which determined crushing force and thus tablet properties.

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Abstract  

The NRTL model has been used to correlate the data for the aqueous alkanolamine systems of (MEA+H2O), (DEA+H2O) and (MDEA+H2O). The model was successfully applied to correlate simultaneously the excess enthalpy, vapour-liquid equilibria, and low temperature activity coefficients. A large database of data was collected for the investigation and it covers a wide range of composition, temperature and pressures. It was found that the form of the binary interaction parameters used by Posey (1996) with a variable non-randomness parameter gave the best results.

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Summary The properties and quality of silicate glasses strongly depend on the amount of residual dissolved gases. Thus, the knowledge of the quantitative content of different volatile components is of great relevance within the technical production line. Several applications exist for the detection and quantification of a single gas in glass. Up to now no available technique provides simultaneous and quantitative information on different gases in a single run. We have developed a new technique to detect the most common volatiles (H2O, CO2, SO2, O2 and N2) simultaneously and quantitatively in silicate glasses with the help of a modified Netzsch TG/MS system. One characteristic feature of this new method is the direct coupling of a thermo balance and a mass spectrometer without the use of any capillary or skimmer system.

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Summary  

In this paper, a description is made of the survey that was undertaken, for the first time, about the situation of radiochemistry activities in the Region of Latin America, comprising twenty countries from South America, Central America and the Caribbean. It became clear from this study that very strong differences exist between the countries and that most of the nuclear facilities in operation, such as nuclear reactors, hot cells, radiochemical laboratories and cyclotrons are concentrated in seven countries, accompanied by research and educational activities. A detailed study of the situation and trends in the Latin American countries is presented, as regards teaching and other activities related to Radiochemistry, as well as a series of suggestions for preservation of knowledge in the field.

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The economy of glass-making is strongly correlated with the energy expended per unit of molten glass. With modified DTA equipment it is possible to get information about the energy consumed to heat the raw materials to the melting temperature, including the energy effects in a batch reaction. The influence of different concentrations of batch materials (cullets and slags) on the energy expended was investigated.

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The control and optimization of the glass-making process is a serious problem in glass production. An EGD procedure involving high-temperature vacuum extraction and total pressure measurement allows determination of the fining state (Läuterzustand) and fining behaviour (Läuterverhalten). The fining state is characterized by the contents of CO2, N2 and other gases from the batch reactions, and gas inclusions. Oxygen evolved in a second step is characteristic for the fining behaviour.

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Abstract  

The fast transfer system in the DR 2 reactor for irradiation at a thermal neutron flux density of 1013 n·cm−2·sec−1 was used for the determination of lithium by the7Li(n, γ)8Li reaction. β-counting with a large perspex Cerenkov detector begun at 0.3 s after the end of irradiation, and multi-scaler data was accumulated in 300 channels at 0.1 s per channel. With a suitable choice of discrimination level only16N and background interfere, and the 0.84 s half-life of8Li was resolved by the method of weighted least squares. Results are presented for 36 international geochemical reference materials, and for a few biological samples, including BOWEN's kale and the NBS Standard Reference Material 1571 Orchard Leaves.

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Journal of Thermal Analysis and Calorimetry
Authors: V. Roháč, M. Fulem, H.-G. Schmidt, V. Růžička, K. Růžička, and G. Wolf
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