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  • Analytical Chemistry and Spectroscopy  (1)
  • DTA  (1)
  • *Muscle Relaxation
  • 1990-1994  (2)
  • 1980-1984
  • 1993  (2)
Collection
Keywords
Publisher
Years
  • 1990-1994  (2)
  • 1980-1984
Year
  • 1
    Electronic Resource
    Electronic Resource
    A study on the thermal decomposition of iron-cobalt mixed hydroxides (1993)
    Springer
    Journal of thermal analysis and calorimetry 39 (1993), S. 309-321 
    Details
    ISSN: 1572-8943
    Keywords: DTA ; electrical conductivity ; mixed hydroxides ; TG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Mittels TG, DTA und der Kinetik von Messungen der isothermen Zersetzung und der elektrischen Leitfähigkeit wurde die Zersetzung von Fe(OH)3 in reinem Zustand und vermengt mit Co(OH)2 untersucht. Die thermischen Produkte wurden mittels Röntgendiffraktion und IR-Spektroskopie charakterisiert. TG und DTA zeigen, daß die Zersetzung von Eisen(III)-hydroxid und die Bildung von -Fe2O3 durch Gegenwart von Co2+ verzögert wird. Die Zersetzungskinetik zeigt, daß die Mischproben mehr Energie für die Thermolyse benötigen. Die Untersuchung der thermischen Produkte zeigt die Bildung von Cobaltferrit bei Zusatz vonx=1 oder 1,5 Cobalthydroxid. Die elektrische Leitfähigkeit nimmt bei der thermischen Zersetzung in Gegenwart von niedrigen Co2+-Konzentrationen (x=0.2) durch Verbrauch der bei der Thermoanalyse geschaffenen Löcher ab. Das monotone Ansteigen der -Werte bei steigender Co2+-Konzentration stimmt mit dem Überspringen von Elektronen zwischen Fe2+ und Co3+ überein.
    Notes: Abstract Thermal decomposition of pure Fe(OH)3 and mixed with Co(OH)2 were studied using TG, DTA, kinetics of isothermal decomposition and electrical conductivity measurements. The thermal products were characterized by X-ray diffraction and IR spectroscopy. The TG and DTA analysis revealed the presence of Co2+ retards the decomposition of ferric hydroxide and the formation of α-Fe2O3. The kinetics of decomposition showed that the mixed samples need higher energy to achieve thermolysis. The investigation of thermal products of mixed samples indicated the formation of cobalt ferrite on addition ofx=1 or 1.5 cobalt hydroxide. The electrical conductivity accompanying the thermal decomposition decreases in presence of low ratio of Co2+ (x=0.2) via the consumption of holes created during thermal analysis. The continuous increase in σ values on increasing of Co2+ concentration corresponded to the electron hopping between Fe2+ and Co3+.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01983530
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  • 2
    Electronic Resource
    Electronic Resource
    Fullerene-linked particles as LC chromatographic media and modification of their electron donor/acceptor properties by secondary chemical reactions (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 5 (1993), S. 223-235 
    Details
    ISSN: 1040-7685
    Keywords: fullerene-linked polymer ; fullerene-linked silica ; synthesis ; stationary phases ; microcolumns ; polycyclic aromatics ; polychlorinated biphenyls ; environmental contaminants ; liquid chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fullerenes (C60 and C70) linked to small silica or polymer particles provide novel chromatographic stationary phases with electron donor/acceptor surface interactions that may parallel those of aromatic carbons. Separations of fullerenes and aromatic compounds frequently encountered as environmental contaminants were investigated using LC microcolumns containing either particles prepared from BrHC60 linked to amino-silica (Spherisorb-NH2, Phenomenex) or porous polymers containing ca. 12% fullerene by weight. The polystyrene divinylbenzene (PSDVB)-C60/70H column had greater capacity (k') than the Si—NH—C60/70H column. Toluene and polycyclic aromatic hydrocarbons (PAHs), naphthalene, anthracene, pyrene, and perylene, were retained in the order of increasing ring number; nitro-substituents increased retention; and chlorinated-dibenzo-p-dioxins and -dibenzofurans were more strongly retained than their parent compounds. PCB congeners with no chlorine in the ortho, ortho'-positions are co-planar and are strongly retained; for these isomers, retention increased with higher chlorination. We demonstrate that surface-linked fullerenes can also accommodate further chemical modification through the addition of 2-(4-nitrophenyl)ethyl or -NH—CH2CH2NH2 moieties to yield altered electron donor/acceptor affinity. Separations appear to be derived primarily from aromatic electron induced dipole-dipole or electron-pair donor or acceptor interactions (charge transfer complexes). Except for the fullerenes, surface interactions with compounds are largely suppressed with methylene chloride as the mobile phase.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mcs.1220050307
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