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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Environmental geology 39 (2000), S. 1059-1062 
    ISSN: 1432-0495
    Keywords: Key words River water ; Bed sediment ; Trace metal ; Heavy metals ; River pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The water and bed-sediment pollution status of the Padma River was determined by analysis of representative samples for selected metals and ions. Water and bed-sediment samples were collected at a T-dam, Rajshahi, Bangladesh, for 7 months. Water and silt-metal content analysis was performed using atomic absorption spectrophotometry or other analytical methods. The data showed the variation of the metal ion-levels in water as follows: Ca 17.11–48.37 ppm, Na 17.51–20.09 ppm, K 1.00–3.60 ppm, Cr 2.80–7.00 ppm, and SO4 4.17–5.48 ppm; in bed sediment, the levels were Cr 35–1050 ppm and Pb 12–48 ppm. The occurrence of Na, K and Ca was in the normal range (US EPA permissible limit), but the levels of Cr in water were much higher than the permissible limit. The SO4 ion content was well below the pollution level. The concentration of Pb in the bed sediment was within the permissible limit for the standard International Atomic Energy Agency (IAEA) Soil-5a, but the concentration of Cr in the bed sediment was significantly higher than the permissible limit for the standard IAEA Soil-5a. Thus the Padma river water was polluted with Cr. The occurrence of some ions showed a monthly variation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of environmental contamination and toxicology 61 (1998), S. 44-50 
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 11 (1976), S. 2082-2086 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The optical absorption spectra of cerium (III) and cerium (IV) in Na2O-B2O3, Na2O-SiO2, Na2O-P2O5 glasses, and in H2O-H2SO4 and H2O-H3PO4 solutions have been studied. Individual molar extinction coefficients of cerium (III) and cerium (IV) at different wavelengths (350 to 200 nm) have been estimated. In all the glasses and solutions, cerium (IV) produces a very strong and broad charge transfer band around 250 nm; the intensity, half-width, and position of this band change appreciably with glass composition. Cerium (III) in glass and in aqueous solution produces a number of absorption bands in the ultraviolet region corresponding to the f → d transitions. The cerium (III) bands are sharp and well resolved in Na2O-P2O5 and in low-alkali borate glasses; the sharpness of resolution deteriorates in Na2O-SiO2, and in high-alkali borate glasses. The intensity of cerium (III) absorption also changes with glass composition. In all the glasses the molar extinction coefficient of cerium (IV) is 5 to 10 times stronger than that of cerium (III).
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 12 (1977), S. 766-770 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The ferrous-ferric equilibrium in different BaO-B2O3 melts containing iron oxides have been studied as functions of temperature and total iron concentration. On equilibrating the melts at 1200° C with air, 3 to 6% of the total iron was reduced to the ferrous state. The equilibrium ferric/ferrous ratio in the melt decreased with increasing temperature and with decreasing BaO content of the melt. Total iron content (in the concentration range of 0.6 to 11.5 wt% Fe) had no significant effect on the equilibrium ferric/ferrous ratio of the melts.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 13 (1978), S. 1499-1502 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The influence of the pH of aqueous solutions on the chemical durability of two glasses in the system Na2O-FeO-Fe2O3-SiO2 has been compared with that of two glasses in the system Na2O-MgO-Al2O3-SiO2 where equimolar substitution of MgO for FeO and Al2O3 for Fe2O3 have been made. The presence of Fe2O3, and particularly of Al2O3, in glass reduces its alkali extraction in the pH range 4 to 9. The extraction results have been discussed and interpreted in the light of the available standard thermochemical data for the component oxides of these glasses.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 11 (1976), S. 2082-2086 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The optical absorption spectra of cerium (III) and cerium (IV) in Na2O-B2O3, Na2O-SiO2, Na2O-P2O5 glasses, and in H2O-H2SO4 and H2O-H3PO4 solutions have been studied. Individual molar extinction coefficients of cerium (III) and cerium (IV) at different wavelengths (350 to 200 nm) have been estimated. In all the glasses and solutions, cerium (IV) produces a very strong and broad charge transfer band around 250 nm; the intensity, half-width, and position of this band change appreciably with glass composition. Cerium (III) in glass and in aqueous solution produces a number of absorption bands in the ultraviolet region corresponding to the f → d transitions. The cerium (III) bands are sharp and well resolved in Na2O-P2O5 and in low-alkali borate glasses; the sharpness of resolution deteriorates in Na2O-SiO2, and in high-alkali borate glasses. The intensity of cerium (III) absorption also changes with glass composition. In all the glasses the molar extinction coefficient of cerium (IV) is 5 to 10 times stronger than that of cerium (III).
    Type of Medium: Electronic Resource
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