Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 2000-2004  (14)
  • 1995-1999  (12)
Material
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Bingley : Emerald
    Environmental management and health 12 (2001), S. 67-78 
    ISSN: 0956-6163
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Medicine , Economics
    Notes: The continent of Antarctica consists of 14 million km2, roughly equivalent to the whole of South America, and is of immense interest to humanity, in particular to the countries of the Antarctic Treaty. The Antarctic continent is the continent of superlatives: it is almost isolated from the rest of the continents, and is severely cold, windy, and dry. In winter, the Antarctic area increases to nearly 32 million km2, because of formation of a 1,000km wide ice-belt. The average depth of ice on the continent is in the order of 2,000m, and in the transantarctic region this depth is 4,800 meters. Antarctica is the biggest sweet water reservoir of the planet earth. Icebergs are common and huge ones (190km in length and 130km wide) have also been observed. The minimum temperature recorded (–89.2°C) at Vostok (Russian base) on 21 July 1983 is also the minimum recorded environmental temperature on the planet earth. Because of extreme temperature variations the Antarctic winds have high velocity. The environment is very dry and at the center of the continent the dryness is of the same magnitude as in the driest desert anywhere on the planet. This is the only uninhabited continent of the planet, except for some 50 research bases which cover an insignificant area located on the continent and the Antarctica Peninsula. Because of its economic, strategic, geopolitical, scientific, meteorological, and oceanographic importance and possible exploitation in the future, Antarctica has been attracting greater attention every day. Antarctica is basically concentrated around the South Pole and it touches the Atlantic, Pacific, and Indian Oceans. Brazil, in common with many other nations, has geopolitical interests and in untapped mineral deposits (considerable deposits of coal, petroleum, gas). In the south, where the Atlantic, Pacific and Indian Oceans meet, the cold water of Antarctica is the habitat housing hundreds of species of sea life. Unrestricted and unbalanced exploitation of Antarctica could cause changes in the meteorological and oceanographic balance. In the present paper, the Brazilian Antarctic Program, and summarized results of studies of Antarctic soil, rocks, and sediments are reported.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of radioanalytical and nuclear chemistry 190 (1995), S. 327-332 
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract 57Fe Conversion electron Mössbauer spectroscopy, X-ray diffractometry and electron microprobe measurements were performed on Fe−Ni−Cr alloys coatings electrochemically deposited at different times (from 1 to 29 minutes). Significant differences have been found among the Mössbauer spectra of samples examined. The changes are also reflected by the hyperfine field distribution derived from the spectra. The observed changes can be associated with changes in the magnetic anisotropy and in the short range ordering in correlated to the duration of electrochemical deposition.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of radioanalytical and nuclear chemistry 210 (1996), S. 105-118 
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A new user-friendly software for analysis of Mössbauer-spectra has been developed. The program makes use of the advantages provided by the current generation of fast personal computers. An Evolution Algorithm1,2 is used for global search of Mössbauer parameters in order to enhance the reliability of the obtained results. Fitting of Lorentzians, Pseudo-Voigt line profiles, and deriving hyperfine-field distributions including correlations and combinations and Mössbauer Line Sharpening by Fourier transformation provide a wide range of applicability.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of radioanalytical and nuclear chemistry 232 (1998), S. 151-158 
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Eight di-n-butyltin(IV) complexes with glycolic, 2-hydroxy-propionic, succinic and malic acids, have been prepared by two different procedures. The compounds were characterised by elemental analysis, FTIR, Raman and119Sn Mössbauer spectroscopy. The IR and Raman data indicated the presence of bidentate and/or monodentate carboxylate groups, non linear C−Sn−C bonds, and Sn−O bonds within the complexes. The results of Mössbauer spectroscopic measurements, based on point-charge model calculations, have shown the occurrence of trigonal bipyramidal environment in the central tin(IV) atom, besides the octahedral and tetrahedral structure.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of radioanalytical and nuclear chemistry 246 (2000), S. 57-60 
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract 151Eu Mössbauer spectrum of IR-transmitting calcium aluminate glass, 60CaO·32Al2O3·5Fe2O3·3Eu2O3, consists of a broad peak due to distorted Eu(III) with δ and Δ values of 0.91 and −2.02 mm·s−1, respectively. Debye temperatures (θD) of 360 and 320 K were obtained from the temperature dependence of absorption area (A) and that of δ, respectively. These θD values indicate that Eu(III) atoms occupy substitutional sites of distorted Al(III)O4 tetrahedra in calcium aluminate glass. The δ value of 0.62 mm/s obtained from the heat-treated sample (glass ceramic) indicates that Eu(III)-O bonds became less covalent. A smaller Δ value of −1.20 mm·s−1 was obtained for Eu(III) in the glass ceramic, indicating less distorted Eu(III)O4 tetrahedra.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract 151Eu and 141Pr Mössbauer spectroscopy was applied to study the effects of Pr substitution for Eu or Ba atoms in Eu1-x Pr x Ba2Cu3O7-δ and EuBa2-x Pr x Cu3O7-δ, respectively. It was found that there exists a correlation between the 151Eu isomer shift and the onset temperature of the superconducting transition, independent of the location of Pr. This shows that the extra electrons provided by the Pr increase the electronic density in the copper oxide planes and in the 4f orbitals of Eu31, simultaneously. The polycrystalline compound EuBa1.3Pr0.7Cu3O7-δ has been investigated by 141Pr Mössbauer spectroscopy. The observed 141Pr isomer shift, δ(4.2 K) = 0.10(15) mm/s relative to PrF3, reflects a valence state of 3+ for the Pr located at the Ba site in EuBa1.3Pr0.7Cu3O7-δ, being in contrast to the valence state of 3.4+ found earlier for Pr which was situated at the rare earth site. This means that the valence state of Pr substituted for Eu is different from that of Pr substituted for Ba. These results suggest that the suppression of superconductivity by Pr substituted for the rare earth atoms is a consequence of the hole filling effect.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Mössbauer, FTIR and XRD analyses showed that in aqueous medium in air in the presence of L-tryptophan (Trp) or indole-3-acetic acid (IAA) the ambient-temperature ageing of the precipitates formed from ferrous sulphate at pH∼7 gave composite phases with varying proportions of γ-FeOOH (a dominating crystalline phase), α-FeOOH (both fine-grained, showing superparamagnetic behaviour at 298 K, and relatively better crystallized) and amorphous ferric hydroxide. The experimental data suggested a competition for adsorption sites at the oxyhydroxide surface in the suspension during phase transformations, as well as the transformation of γ-FeOOH (and/or amorphous ferric hydroxide) to α-FeOOH via the dissolution-reprecipitation mechanism. The formation of certain ferric oxyhydroxide phases in the presence of Trp and IAA — released e.g., in the course of bacterial and plant metabolism — can contribute to the regulation of soil mineral composition.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract 57Fe and 151Eu Mössbauer spectroscopy as well as RF susceptibility measurements were applied to study the effects of Pr substitution either into the rare earth or into the Ba site in Eu1−x Pr x Ba2Cu3O7−δ and EuBa2−x Pr x Cu3O7−δ, respectively. Site mixing of Pr between the rare earth and Ba sites could be excluded by the utilization of 57Fe Mössbauer spectroscopy. It was found that there exists a correlation between the 151Eu isomer shift and the onset temperature of the superconducting transition independent of the location of Pr. RF susceptibility measurements provide an evidence for a difference in the magnetic moment of Pr substituted for the Eu or Ba sites. The obtained results can be explained by hole filling as the dominant effect of Pr substitution.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of radioanalytical and nuclear chemistry 246 (2000), S. 379-384 
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract 57Fe transmission Mössbauer spectroscopy and X-ray diffractometry were used to study clay mineral samples originated from two different regions (Um-arrazm and Alkawasim) of Libya in order to get information about their mineralogical composition to assess their potential for use in the Libyan oil industry. In the samples originated from Um-arrazm calcite, akaganeite and nontronite while in the samples originated from Alkawasim quartz, akaganeite, montmorillonite, kaolinite, illite, mica and hematite were identified with different ratios by using diffraction method. The differences in the phase composition of iron-containing phases of samples from different localities have reflected in the complex Mössbauer spectra at both 300 K and 80 K. For the samples originated from Um-arrazm the Mössbauer parameters of subspectra were identified as nontronite and akaganeite.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...