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Abstract  

Doping of crystalline /CoEDTA/2 Ba and /Co(en)3/(NO3)3 by60Co2+ creates a thermodynamically dissipative structure which gives rise to an oscillatory exchange of the radiocobalt with the inactive Co/III/ of the complex ions. The same compounds in which energetic60Co atoms have been produced by neutron irradiation show kinetically the same oscillatory parameters. The Volterra-Lotka model is applied for the oscillations.

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Abstract  

Thermal decomposition processes of selected chemicals used as food preservatives such as sodium formate, sodium propionate, sodium nitrates(V and III) and sodium sulphate(IV) were examined by the derivatographic method. Based on the curves obtained, the number of decomposition stages and characteristic temperatures of these compounds have been found. Mass decrements calculated from TG curves ranged from 28.9% for sodium formate to 77.8% for sodium nitrate(V), while sodium sulphate showed a mass increment of 5.6%. Kinetic parameters such as activation energy (E a ), frequency factor (A ) and reaction order (n ) were calculated from TG, DTG and T curves. Sodium formate shows the highest values of E a and A which amount to 171.7 kJ mol–1 and 5.8⋅1014 s–1 , respectively, while the lowest ones, E a =28.2 kJ mol–1 and A =3.65⋅102 s–1 belong to sodium nitrate(V).

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Abstract  

Prompt gamma ray neutron activation analysis methodologies were standardized using a reflected neutron beam and Compton suppressed γ-ray spectrometer to quantify boron from trace to major concentrations. Neutron self-shielding correction factors for higher boron contents (0.2–10 mg) in samples were obtained from the sensitivity of chlorine by irradiating KCl with and without boron. This method was validated by determining boron concentrations in six boron compounds and applied to three borosilicate glass samples with boron contents in the range of 1–10 mg. Low concentrations of boron (10–58 mg kg−1) were also determined in two samples and five reference materials from NIST and IAEA.

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Acta Alimentaria
Authors: R. Casañas Rivero, P. Suárez Hernández, E. Rodríguez Rodríguez, and C. Díaz Romero

1989 Casañas, R., González, M., Rodríguez, E., Marrero, A. & Díaz, C. (2002): Chemometric studies of chemical compounds in five

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is valid and is not chance correlation. The predicted values by Eq. 7 in comparison with the experimental values [ 50 ] are presented in Fig. 1 . The predicted values for the investigated chemical compounds, the calculated descriptors

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their mixtures to a certain extent. Benson groups adding principle can give danger level of chemical compounds based on the calculated reaction heat of exothermic reaction [ 6 , 7 ]. However, reaction heat is calculated by the integral of the

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Acta Chromatographica
Authors: Steven Yeung, Quanlan Chen, Yongbang Yu, Bingsen Zhou, Wei Wu, Xia Li, Ying Huang, and Zhijun Wang

-layer chromatography was also reported to screen GL based on the peak profiles of polysaccharide hydrolyzates, but it is less sensitive and specific for chemical compounds [ 15–17 ]. More than 400 compounds have been identified in GL, among which

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Abstract  

Experiments carried out with58CoO and58CoS in shaft furnace have shown that cobalt recovery from copper-matte is 70–75% for both chemical compounds and the dynamics of cobalt movement in the shaft furnace and settling tank turns out to be almost independent of these compounds. The tank-in-series model describes well the mixing characteristics in the melting zone of the shaft furnace, and a time-delay model is used to explain the time lag, short circuit and other mixing phenomena during the flow of materials in the settling tank.

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Abstract  

Cryosublimation is one technique, which allows the accumulation of tritium from aqueous solutions using certain chemical compounds. After studying several inorganic compounds such as zeolites and metal salts,1 as well as some humic substances,2 we have now investigated several mono-and polysaccharides, such as glucose, maltose, galactose, starch, agar, and gelatine. Except for starch all of the above mentioned compounds showed a clear enrichment of tritium. The highest value was reached for Agartine, which gave an enrichment factor of 6.2. Since mono-and polysaccharides form weak hydrogen bonds, these results prove again our theory that tritium is preferably accumulated in exchangeable hydrogen bonds.

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Abstract  

The synthesis of new compounds based on Bi2O3 is investigated because they can be used as new environmentally friendly inorganic pigments. Chemical compounds of the (Bi2O3)1–x(Er2O3)x type were synthetized. The host lattice of these pigments is Bi2O3 that is doped by Er3+ ions. The incorporation of doped ions provides interesting colours and contributes to an increase in the thermal stability of these compounds. The simultaneous TG-DTA measurements were used for determination of the temperature region of the pigment formation and thermal stability of pigments.

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