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  • kinetics  (110)
  • Chromatographie, Dünnschicht  (90)
  • Chemistry
  • Humans
  • Immunocytochemistry
  • Life and Medical Sciences
  • Volumetrie
  • Springer  (346)
  • 2000-2004  (81)
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  • 1
    Digitale Medien
    Digitale Medien
    The effects of aqueous solvent structure on the mutarotation kinetics of glucose (1977)
    Springer
    Journal of solution chemistry 6 (1977), S. 203-216 
    Details
    ISSN: 1572-8927
    Schlagwort(e): Glucose ; kinetics ; mixed solvent ; kinetic isotope effect ; enthalpy of activation ; entropy of activation ; tetrahydrofuran ; tert-butanol ; mutarotation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The mutarotation rates of glucose in aqueous mixtures of tetrahydrofuran andtert-butanol in the mole fraction (xi) range 0〈xi〈0.2 have been measured at 5° intervals in the range 5–35°C. The kinetic deuterium isotope effects have been determined for the same solvent compositions at 25 and 35°C. A statistical analysis of the Arrhenius plots indicates that the experimental errors, although small, are too large for the establishment of any compensation behavior between ΔH
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00646739
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  • 2
    Digitale Medien
    Digitale Medien
    Solvent effects on the acid-catalyzed hydrolysis of tetramethylurea (1976)
    Springer
    Journal of solution chemistry 5 (1976), S. 163-169 
    Details
    ISSN: 1572-8927
    Schlagwort(e): Solvent effects ; tetramethylurea ; hydrolysis ; hydrogen bonding ; kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Tetramethylurea was hydrolyzed in aqueous hydrochloric acid at temperatures of 80, 90, and 100°C. All reactions were carried out in an excess of both tetramethylurea and water, with first-order dependence on acid concentration being observed. As the concentration of water was increased, the rate of hydrolysis decreased until equimolar amounts of water and tetramethylurea were present. Subsequent addition of water had no effect on the observed rate.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00654333
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  • 3
    Digitale Medien
    Digitale Medien
    Why Does the Linear Driving Force Model for Adsorption Kinetics Work? (2000)
    Springer
    Adsorption 6 (2000), S. 137-147 
    Details
    ISSN: 1572-8757
    Schlagwort(e): adsorption ; kinetics ; linear driving force model ; process design
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Physik , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Abstract The Linear Driving Force (LDF) model for gas adsorption kinetics is frequently and successfully used for analysis of adsorption column dynamic data and for adsorptive process designs because it is simple, analytic, and physically consistent. Yet, there is a substantial difference in the characteristics of isothermal batch uptake curves on adsorbent particles by the LDF and the more rigorous Fickian Diffusion (FD) model. It is demonstrated by using simple model systems that the characteristics of the adsorption kinetics at the single pore or the adsorbent particle level are lost in (a) evaluating overall uptake on a heterogeneous porous solid, (b) calculating breakthrough curves from a packed adsorbent column, and (c) establishing the efficiency of separation by an adsorptive process due to repeated averaging of the base kinetic property. That is why the LDF model works in practice.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008965317983
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  • 4
    Digitale Medien
    Digitale Medien
    Effect of K, Cs and Ba on the kinetics of NH3 synthesis over carbon-based ruthenium catalysts (2000)
    Springer
    Catalysis letters 68 (2000), S. 163-168 
    Details
    ISSN: 1572-879X
    Schlagwort(e): ammonia synthesis ; kinetics ; ruthenium catalysts ; promotional effect
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The kinetics of NH3 synthesis over carbon-based ruthenium catalysts promoted with barium or alkali was studied. Both the ammonia partial pressure dependencies of the reaction rates (T = 400°C, p = 63 bar, H2 : N2 = 3 : 1) and the pressure variations of the activity (T = 370°C, p= 4–63 bar, H2 : NN2 = 3 : 1) were found to be different for Ba and for the alkali (K, Cs). Ba–Ru/C proved to be more sensitive to the NH3 content and to the total pressure. The rate of synthesis over the alkali-promoted catalysts is, in turn, much stronger influenced by the ruthenium dispersion. TOFs of NH3 synthesis for the promoted samples at 370°C and 4 bar (Ba 0.085 1/s, Cs 0.05 1/s, K 0.035 1/s) are significantly higher than that for the Ru(0001) basal plane (0.0085 1/s results from the literature data at 370°C, 2 bar). The most active Ru/C samples (Ba or Cs) exceed significantly the fused iron catalyst, especially at high conversions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1019024629261
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  • 5
    Digitale Medien
    Digitale Medien
    Mechanism of the hydrodenitrogenation of o-toluidine and methylcyclohexylamine over NiMo/γ-Al2O3 (2000)
    Springer
    Topics in catalysis 11-12 (2000), S. 327-333 
    Details
    ISSN: 1572-9028
    Schlagwort(e): hydrodenitrogenation ; toluidine ; methylcyclohexylamine ; kinetics ; nickel-promoted molybdenum sulphide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The hydrodenitrogenation (HDN) of o-toluidine and its reaction intermediates was studied over a NiMo/γ-Al2O3 catalyst. The kinetics of the HDN of methylcyclohexylamine and of the hydrogenation of cyclohexene were also studied. Hydrogenation of o-toluidine alone produces methylcyclohexene and methylcyclohexane. When a sufficient quantity of cyclohexene is added during the HDN of toluidine, methylcyclohexylamine, the first intermediate in the hydrogenation of toluidine, becomes detectable. Because of its strong adsorption constant and high rate constant for reacting further to methylcyclohexene and methylcyclohexane, methylcyclohexylamine is not observed in the HDN of toluidine. Adding cyclohexene decreases the adsorption of methylcyclohexylamine, thus enabling its detection. The rate and adsorption constants of methylcyclohexylamine and cyclohexene in the HDN of methylcyclohexylamine were calculated by fitting the kinetic data to a Langmuir–Hinshelwood equation. A two-site model was used to describe the surface reactions, with one site for the methylcyclohexylamine reactions and the other for the cyclohexene reaction.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1027208200169
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  • 6
    Digitale Medien
    Digitale Medien
    Static and Kinetic Studies on the Adsorption Behavior of Sulfadiazene (2000)
    Springer
    Adsorption 6 (2000), S. 349-357 
    Details
    ISSN: 1572-8757
    Schlagwort(e): sulfadiazene ; adsorption ; kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Physik , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Abstract To investigate the nature of interactive forces between sulfadiazene molecules and alumina surface the experiments were performed for the adsorption of sulfadiazene (SD) from its aqueous sulution onto the alumina surfaces at 25 ± 0.2°C and the influence of factors such as increasing concentration of SD (4.0–20.0 × 10−3 mol cm−3), the time required for adsorption equilibrium, pH (2.0–12.0) and temperature (5–45°C) of the adsorption medium, the presence of ions like Cl−, SO2− 4 and PO3− 4 (0.01–0.30 M) and organic solvents (5% v/v) were observed on the course of adsorption of SD. Various adsorption and kinetic parameters such as adsorption coefficient, the rate constants for adsorption and desorption were also evaluated. The results of the above cited studies facilitated to formulate the mechanisms of interaction between SD and alumina surfaces. From application view point the present work may be a potential tool for an effective chromatographic separation of sulfa drugs from industrial effluents.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1026517117239
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  • 7
    Digitale Medien
    Digitale Medien
    NO reduction over La2O3 using methanol (2000)
    Springer
    Catalysis letters 64 (2000), S. 65-75 
    Details
    ISSN: 1572-879X
    Schlagwort(e): NO reduction ; CH3OH ; La2O3 ; methyl nitrite ; kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Nitric oxide (NO) reduction by methanol was studied over La2O3 in the presence and absence of oxygen. In the absence of O2, CH3OH reduced NO to both N2O and N2, with selectivity to dinitrogen formation decreasing from around 85% at 623 K to 50–70% at 723 K. With 1% O2 in the feed, rates were 4–8 times higher, but the selectivity to N2 dropped from 50% at 623 K to 10% at 723 K. The specific activities with La2O3 for this reaction were higher than those for other reductants; for example, at 773 K with hydrogen a specific activity of 35 μmol NO/s m2 was obtained whereas that for methanol was 600 μmol NO/s m2. The Arrhenius plots were linear under differential reaction conditions, and the apparent activation energy was consistently near 14 kcal/mol with CH3OH. Linear partial pressure dependencies based on a power rate law were obtained and showed a near‐zero order in CH3OH and a near‐first order in H2. In the absence of O2, a Langmuir–Hinshelwood type model assuming a surface reaction between adsorbed CH3OH and adsorbed NO as the slow step satisfactorily fitted the data, and the model invoking two types of sites provided the best fit and gave thermodynamically consistent rate constants. In the presence of O2 a homogeneous gas‐phase reaction between O2, NO, and CH3OH occurred to yield methyl nitrite. This reaction converted more than 30% of the methanol at 300 K and continued to occur up to temperatures where methanol was fully oxidized. Quantitative kinetic studies of the heterogeneous reaction with O2 present were significantly complicated by this homogeneous reaction.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1019036431195
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  • 8
    Digitale Medien
    Digitale Medien
    Oxidation of dicyclopentadiene catalyzed by palladium(II) acetate and p-benzoquinone in the presence of inorganic acid (2000)
    Springer
    Catalysis letters 69 (2000), S. 103-107 
    Details
    ISSN: 1572-879X
    Schlagwort(e): dicyclopentadiene ; Wacker oxidation ; Pd(AcO)2 ; benzoquinone ; kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The oxidation of dicyclopentadiene catalyzed by palladium(II) acetate and benzoquinone in the presence of perchloric acid was studied. Tricyclodecenone in high selectivity (85–98%) at a conversion of dicyclopentadiene up to 76% was obtained. The kinetic model assumed the significant inhibition complexation between dicyclopentadiene and tricyclodecenone with the catalytic species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1019053402854
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  • 9
    Digitale Medien
    Digitale Medien
    A sulphated glycopeptide in human supragingival calculus extracts (1977)
    Springer
    Calcified tissue international 23 (1977), S. 13-17 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Dental calculus ; Glycopeptide ; Chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary A method is described for the isolation and purification of a sulphated glycopeptide from human supragingival calculus. The compound was isolated after using EDTA treatment, 2 M CaCl2 extraction, proteolytic digestion, ethanol precipitation, and finally purified by DEAE cellulose chromatography. It migrated as a single component on cellulose acetate electrophoresis, and chemical and infrared spectral analysis showed the presence of covalently attached sulphate groups. The sulphated glycopeptide was distinguished from being a sulphated glycosaminoglycan.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02012761
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  • 10
    Digitale Medien
    Digitale Medien
    The consequences of the mutual recognition of measurement standards for international metrology (2000)
    Springer
    Accreditation and quality assurance 5 (2000), S. 409-413 
    Details
    ISSN: 1432-0517
    Schlagwort(e): Key words Metrology ; Comparisons ; Chemistry ; Standards
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract  After stressing the importance in the modern world of accurate and reproducible measurements, the actions taken by the Bureau International des Poids et Mesures to set up, together with the regional metrology organizations, a series of key comparisons are described. They are the technical foundation of a mutual recognition of national measurement standards arrangement prepared in conjunction with the National Metrology Institutes (NMIs). This arrangement also includes the recognition of calibration and measurement certificates issued by these institutes. Then, the consequences of this arrangement for trade are described. The case of chemical analysis is illustrated by the application of the Kyoto protocol on the reduction of greenhouse gases. But the global workload to be taken up by the International Committee of Weights and Measures, its Consultative Committee for Amount of Substance and the NMIs is huge.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s007690000228
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  • 11
    Digitale Medien
    Digitale Medien
    Proteins of the periodontium (1977)
    Springer
    Calcified tissue international 23 (1977), S. 39-44 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Dental cementum ; Collagen ; Protein ; Chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary Cyanogen bromide (CNBr) peptides were prepared of the insoluble collagen of bovine dental cementum. Following chromatographic separation, the peptides were identified by their amino-acid composition. Type I collagen ([α1(I)]2α2) accounted for more than 90% of the organic matrix, while Type III collagen ([α1(III)]3) was present at a level of approximately 5%. Amino-acid analyses revealed that the CNBr peptides from α1(I) and α2 chains of cementum closely resembled the corresponding peptides from calf skin. The only systematic difference was a higher level of hydroxylation of prolyl and lysyl residues of the cementum peptides.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02012764
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  • 12
    Digitale Medien
    Digitale Medien
    Calcium deficiency, pregnancy, and lactation in rats (1977)
    Springer
    Calcified tissue international 23 (1977), S. 87-94 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Calcium ; Osteoporosis ; Lactation ; Chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The calcium homeostatic mechanism was challenged in adult female rats by feeding them a calcium-deficient diet containing oxalate, and by subjecting them to pregnancy and lactation. The regimen caused a substantial weight loss, especially in those animals which reared their young well. Severe hypocalcaemia was observed in the lactating rats. Serum-P was slightly elevated. The content of hydroxyproline in serum was considerably elevated, reflecting the degree of calcium deprivation. Serum proteins were least influenced. The calcium depriving regimen reduced the growth of long bones, but did not stop it. The ash content of the bones was considerably reduced, the degree of reduction depended on the degree of calcium deprivation. Ash as percentage of total bone organ was reduced, but not to the same extent as total ash. Analyses of different parts of femur showed that the proximal and distal parts had lost more bone mineral than the diaphyseal shaft. The ash content of cortical bone tissue from the femur was estimated by a volumetric method. No differences were observed between test groups and controls, indicating that no measurable amounts of bone mineral had been removed from the walls of the vascular canals or by osteocytic osteolysis. Planimetric determinations on cross sections from femora disclosed that a great amount of bone had been removed from the endosteal surface of the diaphysis, while the periosteal surface demonstrated reduced bone apposition.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02012771
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  • 13
    Digitale Medien
    Digitale Medien
    Demonstration of enamel matrix proteins on root-analogue surfaces of rabbit permanent incisor teeth (1977)
    Springer
    Calcified tissue international 24 (1977), S. 223-229 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Enamel-cementum-morphology ; Immunocytochemistry ; Biochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The continuously erupting rabbit incisor tooth is normally thought of as having an enamel covered “crown” on its labial surface and a cementum covered “root” on its lingual surface. We have examined both surfaces of continuously erupting rabbit incisor teeth taken from near term embryos by a variety of means, including transmission and scanning electron microscopy, biochemical fractionation, and immunohistochemistry. In all cases, we could detect no qualitative difference in the early extracellular matrices taken from the labial and lingual surfaces of the teeth. Both matrices were shown to be composed of dentin and enamel, although the thickness and geometry of the enamel matrix on the lingual surface was somewhat different from that on the labial surface.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02223320
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  • 14
    Digitale Medien
    Digitale Medien
    Phytochrome photoreversibility: Empirical test of the hypothesis that it varies as a consequence of pigment compartmentation (1978)
    Springer
    Planta 141 (1978), S. 129-134 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Avena ; Immunocytochemistry ; Phytochrome
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Phytochrome of oat (Avena sativa L., cv. Garry) coleoptile cells in the red-light-absorbing form, Pr, is diffusely distributed while after conversion to the far-red-light-absorbing form, Pfr, it is observed only in very small areas within the cell. Comparison of phytochrome photoversibility measurements to the distribution of the pigment within the cell indicates that the spectral assay is not influenced by the observed compartmentalization of the chromoprotein. However, the observed compartmentalization of phytochrome is correlated with a loss in spectrophotometrically detectable Pr.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00387878
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  • 15
    Digitale Medien
    Digitale Medien
    Influence of acetylsalicylic acid on the renal handling of a spironolactone metabolite in healthy subjects (1976)
    Springer
    European journal of clinical pharmacology 10 (1976), S. 43-48 
    Details
    ISSN: 1432-1041
    Schlagwort(e): Spironolactone ; acetylsalicylic acid ; fludrocortisone ; kinetics ; pharmacology ; interaction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The influence of 600 mg acetylsalicylic acid (ASA) on the renal excretion and clearance of canrenone, the principal unconjugated metabolite of spironolactone, was examined in a double-blind crossover study in six healthy subjects. ASA significantly reduced the urinary excretion, and the fractional excretion, of canrenone between 4 — 6 hours after administration of 50 mg spironolactone. The pharmacological activity of spironolactone, assessed simultaneously by alterations in fludrocortisone-induced urinary electrolyte changes, was slightly but not significantly reduced. The reductions in urinary canrenone excretion correlated with changes in the urinary log 10 Na/K ratio. The results suggest that canrenone may be actively secreted at the proximal renal tubule, and that secretion is blocked by ASA or its conjugates. This is a possible mechanism for the pharmacological interaction between ASA and spironolactone which has been described previously.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00561548
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  • 16
    Digitale Medien
    Digitale Medien
    Kinetics and efficacy of theophylline in the treatment of apnea in the premature newborn (1978)
    Springer
    European journal of clinical pharmacology 13 (1978), S. 203-207 
    Details
    ISSN: 1432-1041
    Schlagwort(e): Theophylline ; kinetics ; apnea ; premature newborns ; developmental pharmacology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Aminophylline (theophylline-ethylenediamine) was administered to 27 premature newborns to prevent apneic spells. Of the 22 patients monitored for theophylline concentration, a therapeutic blood level was reached in 19 in 1–2 days, and 3 stayed below it. ‘Toxic’ blood levels (≥20 µg/ml) were reached in 3 cases, one of whom showed signs of toxicity. Theophylline treatment was not efficient in the prevention of apnea when a serious underlying disease was present. Theophylline blood half-life (mean : 27.0 h) and clearance (mean 12.9 ml/h/kg) confirmed the slow elimination pattern of the drug in the premature infant.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00609983
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  • 17
    Digitale Medien
    Digitale Medien
    Kinetic Analysis of the Decomposition of Chelates of Di-alkyldithiocarbamate of Cd(II) (2000)
    Springer
    Journal of thermal analysis and calorimetry 59 (2000), S. 633-642 
    Details
    ISSN: 1572-8943
    Schlagwort(e): cadmium ; dialkyldithiocarbamate ; kinetics ; thermal decomposition ; thermogravimetry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The thermal decomposition kinetics of the solid complexes Cd(S2 CNR2 )2 , where R =C2 H5 , n -C3 H7 , n -C4 H9 or iso -C4 H9 , was studied by using isothermal and non-isothermal thermogravimetry. The superimposed TG/DTG/DSC curves revealed that thermal decomposition reactions occur in the liquid phase. The kinetic model that best fitted the experimental isothermal TG data was the one-dimensional phase-boundary reaction-controlled process R1 . The thermal analysis data suggested the thermal stability sequence Cd(S2 CNBun 2 )2 〉Cd(S2 CNPrn 2 )2 〉Cd(S2 CNBui 2 )2 〉Cd(S2 CNEt2 )2 , which accords with the sequence of stability of the apparent activation energies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010120813517
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  • 18
    Digitale Medien
    Digitale Medien
    Kinetic and Thermodynamic Studies of Facial and Meridional uns-cis-[Co(eddp)gly] Complexes (2000)
    Springer
    Journal of thermal analysis and calorimetry 59 (2000), S. 807-814 
    Details
    ISSN: 1572-8943
    Schlagwort(e): facial and meridional Co(III) complexes ; kinetics ; thermodynamics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Thermal properties of facial and meridional uns-cis-[Co(eddp)gly]0.5H2O complexes were investigated by means of DSC and TG techniques. It wasshown that the processes of thermal decomposition of these complexes are multi-stepdegradation processes, which can also be well separated into individual steps, depending onthe molecular symmetry. Thus, the process of thermal degradation of the meridional isomerof the above complex consists of 4 well-separated steps in the temperature interval from 100to 500°C. The corresponding kinetic and thermodynamic parameters of this process weredetermined, and a possible mechanism is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010157821694
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  • 19
    Digitale Medien
    Digitale Medien
    Thermal Decomposition Kinetics of Some Metal Complexes of N,N-diethyl-n '-benzoylthiourea (2000)
    Springer
    Journal of thermal analysis and calorimetry 61 (2000), S. 955-965 
    Details
    ISSN: 1572-8943
    Schlagwort(e): kinetics ; metal complexes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Thermogravimetry (TG) and differential thermal analysis (DTA) were performed on the complexes with general formula (M(DEBT)n (where M =Fe, Co, Ni, Cu or Ru; n =2, or 3 and DEBT=N,N-diethyl-N'-benzoylthiourea). Derivative thermogravimetric (DTG) curves were also recorded in order to obtain decomposition data on the complexes. The complexes of Fe(III), Co(II), Ni(II), Cu(II) and Ru(III) displayed two- or three-stage decomposition patterns when heated in a dynamic nitrogen atmosphere. Mass loss considerations relating to the decomposition stages indicated the conversion of the complexes to the sulfides or to the corresponding metal alone (Cu, Ru, NiS, CoS or FeS). Mathematical analysis of the TG and DTG data showed that the order of reaction varied between 0.395 and 0.973. Kinetic parameters such as the decomposition energy, the entropy of activation and the pre-exponential factor are reported.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010171230450
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  • 20
    Digitale Medien
    Digitale Medien
    Fast Gas Adsorption Measurements For Complicated Adsorption Mechanisms (2000)
    Springer
    Journal of thermal analysis and calorimetry 62 (2000), S. 429-433 
    Details
    ISSN: 1572-8943
    Schlagwort(e): adsorption ; fast measurement ; gravimetry ; kinetics ; sorption ; kw6
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Jäntti introduced a method to reduce the time required for the stepwise measurement of adsorption isotherms. After each pressure change he measured the adsorbed mass three times and calculated its equilibrium value at the new pressure. In the present paper, we discuss the applicability of this method in a broader scope without starting from a given combination of sorptive and adsorbent and the influence of measuring inaccuracies. The method is applied to detect whether the adsorption process is based on more than one adsorption mechanism or not.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010190131304
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  • 21
    Digitale Medien
    Digitale Medien
    Study of Thermal Decomposition Kinetics of Low-temperature Reaction of Ammonium Perchlorate by Isothermal TG (2000)
    Springer
    Journal of thermal analysis and calorimetry 63 (2000), S. 375-386 
    Details
    ISSN: 1572-8943
    Schlagwort(e): activation energy ; ammonium perchlorate ; decompositon ; isothermal ; kinetics ; thermogravimetry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The kinetics of the thermal decomposition of ammonium perchlorate at temperatures between 215 and 260°C is studied, in this work, by measuring the sample mass loss as a function of time applying the isothermal thermogravimetric method. From the maximum decomposition rate – temperature dependence two different decomposition stages, corresponding to two different structural phases of ammonium perchlorate, are identified. For the first region (215–235°C), corresponding to the orthorhombic phase, the mean value of the activation energy of 146.3 kJ mol–1, and the pre-exponential factor of 3.43⋅1014 min–1 are obtained, whereas for the second region (240–260°C), corresponding to the cubic phase, the mean value of the activation energy of153.3 kJ mol–1, and the pre-exponential factor of 4.11⋅1014 min–1 are obtained.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010136308310
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  • 22
    Digitale Medien
    Digitale Medien
    Theoretical and Experimental Investigations of The Decomposition of 10-methylacridinium Halides (2000)
    Springer
    Journal of thermal analysis and calorimetry 60 (2000), S. 35-43 
    Details
    ISSN: 1572-8943
    Schlagwort(e): kinetics ; 10-methylacridinium halides ; thermodynamics ; thermogravimetric investigations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract 10-Methylacridinium chloride, bromide and iodide were prepared in crystalline forms (the first two salts as monohydrates) and subjected to thermogravimetric investigations. Decomposition of the compounds is initially accompanied by the liberation of water (in case of monohydrates), halomethanes and acridine molecules. As decomposition proceeds, side reactions occur which are reflected in a complex pattern of thermogravimetric curves. TG traces corresponding to the initial decomposition stage were used to determine the kinetic characteristics of the thermal dissociation of the salts. MNDO/d, AM1 and PM3 methods were employed independently to examine reaction pathways and to predict thermodynamic and kinetic barriers for the thermal decomposition of the compounds. These data were subsequently supplemented with theoretically determined crystal lattice energies, which enabled the relevant characteristics for the decomposition of crystalline phases to be predicted. The theoretically predicted characteristics are qualitatively comparable with those originating from thermogravimetric investigations, which allows one to believe that both are valid.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010160132175
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  • 23
    Digitale Medien
    Digitale Medien
    Thermal Decomposition of Triazine Herbicides. I. 1,2-(4-chloro-6-ethylamino-1,3,5-triazin-2-ylamino)-2-methylpropionitrile (cyanazine) (2000)
    Springer
    Journal of thermal analysis and calorimetry 60 (2000), S. 103-110 
    Details
    ISSN: 1572-8943
    Schlagwort(e): cyanazine ; DSC ; kinetics ; thermal stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Cyanazine was taken as an example for investigations under the influence of different conditions on thermal decomposition of triazine herbicides. DSC measurements were carried out under atmospheric pressure and hermetically closed, under pressure 1.3 kPa. The influence of the pressure on the constant reaction rate of decomposition of cyanazine was discussed. It was also proved that the predicted reaction constant rates from isothermal and non-isothermal measurements are consistent.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010132820788
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  • 24
    Digitale Medien
    Digitale Medien
    Influence of Gas Atmosphere on Removal of Sulphate Groups From Titanium Oxide (2000)
    Springer
    Journal of thermal analysis and calorimetry 60 (2000), S. 247-255 
    Details
    ISSN: 1572-8943
    Schlagwort(e): desulfuration ; gas atmosphere ; kinetics ; thermal decomposition ; titanium dioxide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The studies were devoted to determination of the effect of gas atmosphere and its pressure on the second step of decomposition of hydrated titanium dioxide (HTD) promoted by sulfate groups. It has been found that thermal decomposition of HTD at temperatures above 300°C consists of a number of processes such as dehydroxylation, desulfuration, recrystallization and sintering of solid grains, photochemical processes (if the decomposition proceeds in the presence of light) and adsorption of gas phase components (in the presence of air or SO2). Kinetic parameters characterizing this step of decomposition have been determined for processes carried out in vacuum and in argon or air atmospheres (at a pressure of 13.33hPa). The kinetic curves of decomposition carried out in the presence of gases capable of being adsorbed on the surface of partly dehydrated HTD are featured by local extrema due to simultaneous processes of decomposition and adsorption of gas components.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010178130783
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  • 25
    Digitale Medien
    Digitale Medien
    Solid State Coordination Chemistry. The quantitative thermoanalytical study of thermal dissociation reactions (2000)
    Springer
    Journal of thermal analysis and calorimetry 60 (2000), S. 9-15 
    Details
    ISSN: 1572-8943
    Schlagwort(e): coordination compounds ; kinetics ; thermal dissociation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Physicalo-chemical importance of the quantitative study of kineticliability of coordination compounds in thermal dissociation processes is considered. Muchattention is given to the proof of the physicalo-chemical meaning and validity of kineticparameters calculated from thermoanalytical data. Experimental data (thermal dissociation ofcoordination compounds and clathrates with such a matrix) are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010148028796
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  • 26
    Digitale Medien
    Digitale Medien
    The Effect of Cross-linked Polyethylene As a Surface Modifier on Crystallization of Polypropylene (2000)
    Springer
    Journal of thermal analysis and calorimetry 60 (2000), S. 401-407 
    Details
    ISSN: 1572-8943
    Schlagwort(e): cross-linking ; isothermal crystallization ; kinetics ; modification ; polypropylene ; silica
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The effect of addition of silica on the parameters of isothermal crystallization of polypropylene has been investigated. It was found that the covering of the silica surface by a layer of low-density polyethylene leads to a deactivation of the filler regarding the positive effect on the polypropylene crystallization rate parameters. Cross-linking of the surface polyethylene layer results in a stronger attachment of the modifying polymer to the filler surface and the deactivation effect of the silica surface modification is more pronounced.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010129106561
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  • 27
    Digitale Medien
    Digitale Medien
    Formation of Cr(II) Species in the H2/CrO3 System. Parameter control (2000)
    Springer
    Journal of thermal analysis and calorimetry 60 (2000), S. 541-547 
    Details
    ISSN: 1572-8943
    Schlagwort(e): Cr(II) ; chromium trioxide ; kinetics ; reduction ; thermal analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The thermal behaviour of CrO3 on heating up to 600°C in dynamic atmospheres of air, N2 and H2 was examined by thermogravimetry (TG), differential thermal analysis (DTA), IR spectroscopy and diffuse reflectance spectroscopy (DRS). The results revealed three major thermal events, depending to different extents on the surrounding atmosphere: (i) melting of CrO3 near 215°C (independent of the atmosphere), (ii) decomposition into Cr2(CrO4)3 at 340–360°C (insignificantly dependent), and (iii) decomposition of the chromate into Cr2O3 at 415–490°C (significantly dependent). The decomposition CrO3 → Cr2(CrO4)3 is largely thermal and involves exothermic deoxygenation and polymerization reactions, whereas the decomposition Cr2(CrO4)3 → Cr2O3 involves endothermic reductive deoxygenation reactions in air (or N2) which are greatly accelerated and rendered exothermic in the presence of H2. TG measurements as a function of heating rate (2–50°C min−1) demonstrated the acceleratory role of H2, which extended to the formation of Cr(II) species. This could sustain a mechanism whereby H2 molecules are considered to chemisorb dissociatively, and then spillover to induce the reduction. DTA measurements as a function of the heating rate (2–50°C min−1) helped in the derivation of non-isothermal kinetic parameters strongly supportive of the mechanism envisaged.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010142904261
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  • 28
    Digitale Medien
    Digitale Medien
    Kinetic Modeling of Advanced Inorganic Glass-ceramics Formation by Crystal Growth From Pre-existing Nuclei (2000)
    Springer
    Journal of thermal analysis and calorimetry 60 (2000), S. 667-674 
    Details
    ISSN: 1572-8943
    Schlagwort(e): accommodation function ; crystal growth ; glass-ceramics ; kinetics ; number of nuclei ; thermal history
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Kinetic modeling of the crystal growth from pre-existing nuclei was reexamined to obtain a fundamental information about the controlled crystallization of glasses during formation of advanced inorganic glass-ceramics. Methods of kinetic analysis were reviewed by taking account of thermal history of the sample within the temperature range of nucleation. An accommodation function depending on the thermal history was introduced in the kinetic equation. The role of the accommodation function was reinvestigated when determining the activation energy from a series of kinetic curves. The kinetic description of the crystal growth in the samples with different thermal history was generalized by extrapolating the rate behavior to infinite temperature.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010123805594
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  • 29
    Digitale Medien
    Digitale Medien
    Temperature Modulated DSC. Theoretical interpretation (2000)
    Springer
    Journal of thermal analysis and calorimetry 60 (2000), S. 333-343 
    Details
    ISSN: 1572-8943
    Schlagwort(e): base line ; DSC ; kinetics ; modeling ; thermodynamics ; TMDSC
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The application of non-linear heating program to a heat-flux DSC apparatus has attracted much attention. From thermodynamics viewpoint, it is shown that the variation of enthalpy of a sample changing with temperature change is due, to both the true heat capacity of the sample and the enthalpy of some transformations occurring in the sample, characterized by its degree of advance. Using the simple assumption that the rate of the transformation is proportional to the distance from the thermodynamic equilibrium, an electrical model of the thermal event is given. Using the coupled cell model of the DSC apparatus, we show how to obtain the rate of transformation of the sample and heat capacity, which is directly related to the base line of the experiment.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010148200201
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  • 30
    Digitale Medien
    Digitale Medien
    Practical Thermogravimetry (2000)
    Springer
    Journal of thermal analysis and calorimetry 60 (2000), S. 759-778 
    Details
    ISSN: 1572-8943
    Schlagwort(e): decomposition temperature ; error sources ; gas-flow and vapor control ; kinetics ; thermogravimetry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The well-known divergence between the present ‘state of the art’ of thermogravimetry and industrial requirements is discussed. Sources of errors are analyzed and the optimization of measuring conditions is discussed regarding the problems associated with static and dynamic (flow) atmospheres, and interactions between materials and gases or vapors. Recommendations for gas-flow control systems and vapor sources are given. Thermal stability and the kinetics of gas-evolving, reversible, thermal decompositions of solids are discussed. The scope of TG-derived kinetics for practical use is examined. Some new characteristic points of TG curves are proposed and defined, e.g. ‘procedure-independent decomposition temperature’ and ‘augmented decomposition temperature’ (obtained at pseudo-equilibrium conditions).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010187019979
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  • 31
    Digitale Medien
    Digitale Medien
    The Thermodynamic Driving Force in the Kinetic Evaluation of Thermoanalytical Curves (2000)
    Springer
    Journal of thermal analysis and calorimetry 60 (2000), S. 879-886 
    Details
    ISSN: 1572-8943
    Schlagwort(e): driving force ; kinetics ; rate equation ; reversible reactions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract This paper outlines the different ways of taking the distance from thermodynamic equilibrium into account in kinetic studies based on thermoanalytical experiments. The three main approaches are: (i) avoiding or neglecting the effect of the reverse reaction, (ii) describing the influence of distance from equilibrium on apparent kinetic parameters, and (iii) incorporating a driving force factor in the rate equation. Finally, the contradiction of the microscopic nature of the processes and the macroscopic character of the usual rate equation are briefly discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010159708593
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  • 32
    Digitale Medien
    Digitale Medien
    Kinetic Analysis of the Thermal Decomposition of Synthetic Malachite by CRTA (2000)
    Springer
    Journal of thermal analysis and calorimetry 60 (2000), S. 943-954 
    Details
    ISSN: 1572-8943
    Schlagwort(e): CRTA ; kinetics ; self-generated atmospheric conditions ; synthetic malachite ; thermal decomposition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The kinetic behavior of the thermal decomposition of synthetic malachite was investigated by means of CRTA under different conditions of reduced pressure, flowing gases and quasi-isobaric atmospheres. The thermal decomposition was found to proceed at lower temperatures under the influence of the self-generated gases, CO2 and H2O. From a viewpoint of chemical equilibrium, the normal and opposite effects on the overall kinetics were observed for the self-generated CO2 and H2O, respectively. The complexity of the present reaction is also reflected by the variations of the apparent kinetic parameters which depend on the applied and self-generated atmospheric conditions. The practical usefulness of CRTA when applied to a complicated thermal decomposition is discussed as exemplified by the kinetic approaches to the present reaction.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010172111319
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  • 33
    Digitale Medien
    Digitale Medien
    Thermal Studies on Some Lanthanide Complexes (2000)
    Springer
    Journal of thermal analysis and calorimetry 61 (2000), S. 151-156 
    Details
    ISSN: 1572-8943
    Schlagwort(e): complexes ; kinetics ; TG-DTA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Thermal behaviour of a few lanthanide complexes of the type ML3(I) [M=Eu,Gd; HL=4,4,4-trifluoro- 1-(2-napthyl)-1,3-butanedione and EuL30.5dmm dmm=2,6-dimethylmorpholine(II)], has been investigated. From thermogravimetric(TG) curves, the decomposition pattern of the compounds has been analysed on the basis of mass loss data. The order and activation energy of the thermal decomposition reactions have been elucidated. From differential thermal analysis (DTA) studies, the heat of reaction and rate of thermal decomposition reaction have been enumerated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010172926826
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  • 34
    Digitale Medien
    Digitale Medien
    Non-isothermal Kinetic Study of the Heterogeneous Thermal Decomposition of a Mannich Compound (2000)
    Springer
    Journal of thermal analysis and calorimetry 61 (2000), S. 239-242 
    Details
    ISSN: 1572-8943
    Schlagwort(e): kinetics ; Mannich compounds ; thermal decomposition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The authors present data concerning the evaluation of kinetic parameters of the decomposition of a Mannich compound by using the classical method of constant heating rate thermal analysis and the new one of controlled rate thermal analysis (CRTA). The data processed using the CRTA method allow to obtain more reliable kinetic parameters according to the proposed reaction mechanism.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010197632277
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  • 35
    Digitale Medien
    Digitale Medien
    Polypropylene Crystallization in an Ethylene-propylene-diene Rubber Matrix (2000)
    Springer
    Journal of thermal analysis and calorimetry 61 (2000), S. 437-450 
    Details
    ISSN: 1572-8943
    Schlagwort(e): crystallization ; EPDM ; kinetics ; morphology ; PP ; rubber
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The effect of the incorporation of an amorphous immiscible polymer (ethylene-propylene-diene- terpolymer) on the PP crystallization kinetics and thermodynamics is investigated by thermal analysis. The results of the investigation have shown that EPDM acts as a nucleant agent. A marked decrease of the half time of PP crystallization, τ1/2 , as well as a sensible increase of the overall crystallization rate, K n , has been observed in the presence of EPDM. Moreover, at any crystallization temperature, a minimum of τ1/2 , is obtained at 25% EPDM content in the blend. The Avrami model has been successfully applied to describe the crystallization kinetics of the blend. The kinetic curves obtained under non-isothermal conditions confirm the results obtained under isothermal conditions and demonstrate the nucleant action of the EPDM phase on the PP crystallization.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010165317028
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  • 36
    Digitale Medien
    Digitale Medien
    TG and DTA Study of the Thermal Dehydration of Metal-exchanged Zeolite-4A Samples (2000)
    Springer
    Journal of thermal analysis and calorimetry 62 (2000), S. 721-727 
    Details
    ISSN: 1572-8943
    Schlagwort(e): kinetics ; metal exchange ; thermaldehydration ; zeolite
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Zeolite-4A is a hydrated aluminosilicate which becomes more hydrated when exchanged with transition metals. In this work, the dehydration kinetics of cobalt, nickel and copper(II)-exchanged zeolite-4A were studied by means of TG and DTA over the temperature range from 20 to 500°C, and the numbers of water molecules in the metal-exchanged zeolite samples were calculated. It was observed that, as the ionic radius of the hydrated metal increased, the number of water molecules also increased. The loss of water from the zeolite samples generally occurred in the temperature range 100–300°C and was manifested in the DTA graphs by an extended endothermic effect. The DTA curves demonstrated that the peak position shifted towards lower temperatures as the metal concentration increased or, in other words, the water of hydration increased. The kinetic parameters (order of reaction and activation energy) were calculated via the Coats and Redfern method. The process of dehydration was found to follow first-order kinetics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1026725509732
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  • 37
    Digitale Medien
    Digitale Medien
    Kinetic Equations for Thermal Dissociation Processes. Part I. KEKAM equation (2000)
    Springer
    Journal of thermal analysis and calorimetry 63 (2000), S. 359-374 
    Details
    ISSN: 1572-8943
    Schlagwort(e): KEKAM equation ; kinetics ; thermal dissociation of solids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Relationships have been established between the average conversion degree and the dissociation time for polydisperse granular material, taking its grain size distribution into account. It has been checked in which cases the kinetic curves obtained by a numerical solution can be described in terms of KEKAM equation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010184224240
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  • 38
    Digitale Medien
    Digitale Medien
    Critical Analysis of the Isoconversional Methods for Evaluating the Activation Energy. II. The activation energy obtained from isothermal data corresponding to two successive reactions (2000)
    Springer
    Journal of thermal analysis and calorimetry 63 (2000), S. 465-469 
    Details
    ISSN: 1572-8943
    Schlagwort(e): isoconversional methods ; kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract An analysis is presented of the consequences of the use of a one term equation containing apparent activation parameters, instead of the true rate equation to describe two successive decomposition reactions undergone by a solid compound. It is demonstrated that the apparent activation energy, obtained by means of isoconversional differential and integral methods, varies with the conversion degree for a relatively narrow temperature range and with temperature at a given value of the conversion degree. The activation energy values obtained with the isoconversional differential method are higher than the corresponding values obtained with the isoconversional integral method.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010100712853
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  • 39
    Digitale Medien
    Digitale Medien
    Kinetics of Thermal Decomposition of Plumbo-jarosite (2000)
    Springer
    Journal of thermal analysis and calorimetry 59 (2000), S. 869-875 
    Details
    ISSN: 1572-8943
    Schlagwort(e): decomposition ; kinetics ; plumbo-jarosite
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract An investigation was carried out on the kinetics of thermal decomposition of plumbo-jarosite. The kinetic models of dissociation of the compounds in the ore were identified. The results of the kinetic studies and the mechanism of the process are discussed. The thermal decomposition of plumbo-jarosite occurs in three stages: the first up to 763, the second up to 1023 and the third up to 1223 K, the corresponding activation energy values being 62.2, 60.3 and 98.0 kJ mol–1 , respectively.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010122308490
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  • 40
    Digitale Medien
    Digitale Medien
    Thermal Characterization of Passivated Nanometer Size Aluminium Powders (2000)
    Springer
    Journal of thermal analysis and calorimetry 61 (2000), S. 805-818 
    Details
    ISSN: 1572-8943
    Schlagwort(e): aluminium ; ARC ; DSC ; kinetics ; nanometric size ; SDT ; TG
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The thermal properties of Alex, a nanosized Al powder, were determined using various techniques, including DSC, TG, simultaneous TG-DTA (SDT) and accelerating rate calorimetry (ARC). The results demonstrate that the specific heat capacities of nano and micron size Al powders are similar between 30 and 400°C. Dynamic and isothermal methods were used to determine the kinetic parameters for the oxidation reaction of Alex, which was detected at an onset temperature of 481°C. The results obtained were in good agreement with each other. From the ARC experiments, exotherms were detected near 340 and 260°C for experiments started at ambient pressure and at 0.72 MPa, respectively.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010197115003
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  • 41
    Digitale Medien
    Digitale Medien
    Thermal and Spectroscopic Studies on the Decomposition of Some Aminoguanidine Nitrates (2000)
    Springer
    Journal of thermal analysis and calorimetry 61 (2000), S. 861-871 
    Details
    ISSN: 1572-8943
    Schlagwort(e): DAGN ; kinetics ; mechanism and IR spectroscopy ; TAGN ; thermal decomposition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Diaminoguanidine nitrate (DAGN) and triaminoguanidine nitrate (TAGN),potential energetic materials in emerging propulsion technology with high mass impetus at low isochoric flame temperature have been studied as regards kinetics and mechanism of thermal decomposition using thermogravimetry (TG), differential thermal analysis (DTA),infrared spectroscopy (IR) and hot stage microscopy. Kinetics of thermolysis has been followed by isothermal TG and IR. For the initial stage of thermolysis of DAGN the best linearity with a correlation coefficient of 0.9976 was obtained for the Avrami-Erofe'evequation, n=2, by isothermal TG. The activation energy was found to be 130 kJ mol–1 and logA=11.4. The initial stage of thermolysis of TAGN also obeyed the Avrami-Erofe'ev equation, n=2, with a correlation coefficient of 0.9975by isothermal TG and the kinetic parameters are E=160.0 kJ mol–1 and logA=16.0. High temperature IR spectra showed exquisite preferential loss in intensity of the NH2, NH, N–N stretching and CNN bending. Spectroscopic and other results favour deamination reaction involving the rupture of the N–N bond as the primary step in the thermal decomposition.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010113707251
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  • 42
    Digitale Medien
    Digitale Medien
    Fractal Approach in the Kinetics of Solid-Gas Decompositions. Part II (2000)
    Springer
    Journal of thermal analysis and calorimetry 61 (2000), S. 979-984 
    Details
    ISSN: 1572-8943
    Schlagwort(e): kinetics ; nucleation-growth
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The author presents some applications of the fractal geometry in the kinetics of heterogeneous decomposition of solids.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010175415429
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  • 43
    Digitale Medien
    Digitale Medien
    Study of The Mechanism and Kinetic Parameters of The Thermal Decomposition of Cobalt Sulphate Hexahydrate (2000)
    Springer
    Journal of thermal analysis and calorimetry 59 (2000), S. 935-942 
    Details
    ISSN: 1572-8943
    Schlagwort(e): CoSO46H2O ; kinetics ; thermal decomposition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Thermogravimetry (TG-DTG), and differential thermal analysis (DTA) were used in the study of the kinetics of decomposition of cobalt sulphate hexahydrate under an air atmosphere. The kinetics of the particular stages of CoSO4 6H2 O decomposition were evaluated from the dynamic mass loss data. The values of the kinetic parameters for each stage of the thermal decomposition were calculated from the α(T) data by using the integral method, applying the Coats-Redfern approximation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010186628054
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  • 44
    Digitale Medien
    Digitale Medien
    Kinetic Study of the Accelerating Effect of Coal-burning Additives on the Combustion of Graphite (2000)
    Springer
    Journal of thermal analysis and calorimetry 62 (2000), S. 681-685 
    Details
    ISSN: 1572-8943
    Schlagwort(e): coal-burning additive ; combustion ; graphite ; kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The catalytic and accelerating effects of three coal-burning additives (CBA) on the burning of graphite were studied with the help of thermogravimetric (TG) analysis. The kinetic study on the catalytic oxidation of the graphite doped with CBA was carried out and the results were presented. The results show that the CBA can change the carbon oxidation/combustion course by catalytic action and change the activation energy, thus improving the combustion efficiency.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1026769323844
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  • 45
    Digitale Medien
    Digitale Medien
    Critical Analysis of the Isoconversional Methods for Evaluating the Activation Energy. I. Theoretical background (2000)
    Springer
    Journal of thermal analysis and calorimetry 63 (2000), S. 457-463 
    Details
    ISSN: 1572-8943
    Schlagwort(e): isoconversional methods ; kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract It is demonstrated that, if the activation energy depends on the degree of conversion, its values obtained by isoconversional differential and integral methods are different.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010148611036
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  • 46
    Digitale Medien
    Digitale Medien
    Modeling of the Phase Transformation Induced by Ball Milling in Anatase TiO2 (2000)
    Springer
    Journal of materials synthesis and processing 8 (2000), S. 139-144 
    Details
    ISSN: 1573-4870
    Schlagwort(e): TiO2 ; phase transformations ; mechanical alloying ; kinetics ; modeling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract A high-pressure and high-temperature phase of TiO2 : TiO2 II is formed transiently during room-temperature high-energy ball milling of anatase TiO2 : TiO2 anatase → TiO2 II → TiO2 rutile. Rutile is the only phase present after prolonged ball milling. The present paper focuses on the influences of physical and chemical processing conditions on the transformation kinetics. The effects of two milling parameters on the kinetics of phase transformation of anatase TiO2 were investigated: the nature of milling tools and the powder-to-ball weight ratio R. Granulometric characterizations and TEM observations have demonstrated that the transformation of TiO2 anatase into TiO2 II occurs without fracturing of particles and that TiO2 II nanograins form at the surface of anatase particles. The parameter R affects only the transformation rate. For a given R, the transformation rate is the largest with alumina grinding tools, intermediate with zirconia tools, and the smallest with steel tools. The parameters involved in current models of the mechanical alloying process do not suffice to explain the differences in transformation rates observed here. A parameter, which takes into account the influence of the mechanical properties of grinding materials, is considered.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1011351807629
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  • 47
    Digitale Medien
    Digitale Medien
    Dissolution kinetics of small amounts of oxygen in tantalum alloy T-111 and internal oxide displacement reactions during annealing (1976)
    Springer
    Oxidation of metals 10 (1976), S. 291-309 
    Details
    ISSN: 1573-4889
    Schlagwort(e): tantalum alloy ; oxygen ; dissolution ; kinetics ; oxides
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Oxygen was added to T-111 (Ta-8W-2Hf, wt.%) at 820 and 990°C at an oxygen pressure of about 3×10−4 Torr (4×10−2N/m2). The technique employed permitted predetermined and reproducible doping of T-111 up to 3.0 at% oxygen. Based on the temperature dependence of the doping reaction, it is concluded that the initial rates of oxygen pickup are probably controlled by solution of oxygen into the T-111 lattice. Although hafnium oxides are more stable than those of tantalum or tungsten, analyses of extracted residues indicate that the latter oxides predominate in the as-doped specimens, presumably because of the higher concentrations of tantalum and tungsten in the alloy. However, high-temperature annealing promotes gettering of dissolved oxygen and of other oxides to form hafnium oxides. Small amounts of tantalum and tungsten oxides were still present after high-temperature annealing. Tungsten oxide (WO3) volatilizes slightly from the surface of T-111 at 990°C. The vaporization of WO3 has no apparent affect on the doping reaction.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00612028
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  • 48
    Digitale Medien
    Digitale Medien
    The formation of a double oxide layer on pure copper (1977)
    Springer
    Oxidation of metals 11 (1977), S. 127-132 
    Details
    ISSN: 1573-4889
    Schlagwort(e): Duplex oxides ; copper oxidation ; kinetics ; oxygen partitioning
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The theory for the growth of a double oxide layer proposed by Yurek, Hirth, and Rapp, has been applied to copper using experimental rate-constant data obtained by Valensi. Calculated thicknesses of the layers agree very well with experimentally measured values.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00606399
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  • 49
    Digitale Medien
    Digitale Medien
    Effect of oxide grain structure on the high-temperature oxidation of Cr (1975)
    Springer
    Oxidation of metals 9 (1975), S. 459-472 
    Details
    ISSN: 1573-4889
    Schlagwort(e): Cr ; oxidation ; kinetics ; Cr2O3 grain size ; short-circuit diffusion ; surface ; preparation ; Fe-Cr
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Cr was oxidized in 1 aim O2 at 980, 1090, and 1200°C. ElectropolishedCr and some orientations of etched Cr oxidize rapidly and develop compressive stress in the growing Cr2O3; other orientations oxidize slowly, apparently free of stress. SEM examination of fracture sections shows that the thick oxide is polycrystalline whereas the thin oxide on etched Cr is monocrystalline. It is deduced that the monocrystalline oxide grows by lattice diffusion of cations outward, and the polycrystalline layer by the two-way transport of cation diffusion outward and anion diffusion inward along oxide grain boundaries. The consequent formation of oxide within the body of the polycrystalline layer generates compressive stress and leads to wrinkling by plastic deformation. The activation energy for oxidation of Cr by cation lattice transport is 58 kcal/mole. Polycrystalline Cr2O3 forms on Fe-26Cr alloy, whether electropolished or etched; oxidation is accordingly rapid and accompanied by compressive stress.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00611694
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  • 50
    Digitale Medien
    Digitale Medien
    Kinetics of high-temperature oxidation of boron carbide in oxygen (1976)
    Springer
    Oxidation of metals 10 (1976), S. 85-95 
    Details
    ISSN: 1573-4889
    Schlagwort(e): boron carbide ; oxidation ; kinetics ; chromatography method
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Thermogravimetry and gas-adsorption chromatography were used to study the kinetics of formation of solid and gaseous products during the hightemperature oxidation of compact boron carbide in oxygen at 740 Torr. Oxidation resistance was observed at temperatures up to 1200°C. The main oxidation products were B2O3 and CO2. Oxidation was paralinear; the carbon consumption exceeded the consumption of boron as compared to the ratio of these elements in the compound B4C. This difference resulted in carbon depletion of the carbide layer in the substrate near the scale〉.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00614238
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  • 51
    Digitale Medien
    Digitale Medien
    Influence on the oxidation kinetics of metals by control of the structure of oxide scales (1976)
    Springer
    Oxidation of metals 10 (1976), S. 361-376 
    Details
    ISSN: 1573-4889
    Schlagwort(e): metals ; scale structure ; epitaxy ; kinetics ; diffusion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract An explanation of the deviation from the parabolic law is the treatment which considers both shortcircuit and lattice diffusion in the oxide scale. In this study we examine how the oxidation kinetics are influenced by changing the structure of the scale of copper oxide in order to confirm the role of short-circuit diffusion in determining the oxidation rate. In addition we explain the oxidation kinetics of copper and nickel by using a model of the scale structure which includes recrystallization and grain growth. Results are as follows: (1) The nucleation and growth behavior of oxide have a direct effect on the structure and in turn the oxidation kinetics due to short-circuit diffusion. (2) A modified treatment is valid in the region where volume diffusion and short-circuit diffusion play an important role in which it is necessary to consider the scale structure such as the grain size distribution and the boundary width. (3) When recrystallization takes place it is necessary to consider the model of a two-layered scale structure which is different in properties and morphology. (4) In this region the rate curves are S-shaped when oxide recrystallization takes place and exhibit a transition from a parabolic to an nth-power relationship (n〉2) when grain growth takes place.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00612048
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  • 52
    Digitale Medien
    Digitale Medien
    Oxidation of tantalum in oxygen-nitrogen and oxygen-inert gas mixtures (1977)
    Springer
    Oxidation of metals 11 (1977), S. 225-239 
    Details
    ISSN: 1573-4889
    Schlagwort(e): tantalum ; oxidation ; high temperature ; kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation of tantalum in oxygen-nitrogen and oxygen-inert gas mixtures at925°C has been studied. The oxygen pressure was close to 0.5 atm in all experiments, and partial pressures of the second component of from 0 to 180 Torr were employed. Spherical specimens were used to provide quantitatively significant kinetic data. A model has been proposed which suggests that the oxygen pressure at the reaction interface close to the metal surface is lower than the external pressure because of the finite permeability of the porous outer oxide layer, and that the inert gas effectively reduces the permeability. The model gives good quantitative agreement with the experimental results.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00606059
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  • 53
    Digitale Medien
    Digitale Medien
    Oxidation of cobalt at high temperature (1977)
    Springer
    Oxidation of metals 11 (1977), S. 365-381 
    Details
    ISSN: 1573-4889
    Schlagwort(e): cobalt oxidation ; kinetics ; parabolic rate constant
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Precise values of parabolic rate constants of cobalt oxidation have been determined over a wide range of temperature (950–1300°C) and oxygen pressure (6.58× 10−4−0.658 atm). The dependence of the calculated values of parabolic rate constants k″p on oxygen pressure and temperature can be described by the following empirical equation: $$k''_p = const. \cdot {\text{p}}_{O_2 }^{{\text{1/n}}} \cdot exp ( - {\text{E}}_{\text{k}} /RT)$$ The exponent 1/n decreases with an increase in temperature from 1/3.40 at 950°C to 1/3.96 at 1300°C, whereas the activation energy Ek decreases with an increase in the oxygen pressure from 41.7 to 38.1 kcal/mole.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00608018
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  • 54
    Digitale Medien
    Digitale Medien
    Solid-solid reactions, I: Experimental study of barium metatitanate synthesis (1979)
    Springer
    Oxidation of metals 13 (1979), S. 77-88 
    Details
    ISSN: 1573-4889
    Schlagwort(e): BaTiO3 ; kinetics ; solid state
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The solid-state reaction between barium carbonate and rutile powders to form barium metatitanate BaTiO3 was studied by thermogravimetric analysis, X rays, and microscopy. Phase-stability domains were drawn in a temperature— $${\text{p}}_{CO_2 } $$ , diagram. The dependence of the reaction kinetics on $${\text{p}}_{CO_2 } $$ , $${\text{p}}_{O_2 } $$ or $${\text{p}}_{N_2 } $$ is discussed. In particular, the rate continuously decreases when $${\text{p}}_{CO_2 } $$ , or $${\text{p}}_{N_2 } $$ increases, but it reaches a maximum as a function of $${\text{p}}_{O_2 } $$ .
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00715871
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  • 55
    Digitale Medien
    Digitale Medien
    High-temperature oxidation kinetics of Cu-Si alloys containing up to 4.75 wt.% Si in $$p_{{\text{O}}_{\text{2}} } $$ =0.01 atm and pure CO2 (1978)
    Springer
    Oxidation of metals 12 (1978), S. 323-329 
    Details
    ISSN: 1573-4889
    Schlagwort(e): Cu-Si alloys ; oxidation ; kinetics ; silica
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation of Cu-Si alloys (containing up to 4.75 wt. % Si) in $${\text{p}}_{O_2 } $$ =0.01 atm from 800 to 1000°C has been investigated using thermogravimetry and other techniques. A 0.04% Si alloy followed a parabolic oxidation law with a rate similar to that of pure Cu. As the Si concentration increased the rate decreased and became irregular owing to SiO2 particles or flakes at the alloy-scale interface. It is considered that sintering of SiO2 particles and rupture of the sinter because of contraction during sintering are responsible for the irregular kinetics. A SiO2 layer forms directly on the 4.75% Si alloy which oxidizes uniformly. The SiO2 was always amorphous. In pure CO2 a similar pattern of amorphous SiO2 particles, flakes, and layers occurs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00603576
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  • 56
    Digitale Medien
    Digitale Medien
    The oxidation of Fe-Cr surface and bulk alloys at 300°C (1979)
    Springer
    Oxidation of metals 13 (1979), S. 283-298 
    Details
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; surface alloys ; Fe-Cr alloys ; iron ; kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation behavior of several surface and bulk Fe-Cr alloys and iron at 300°C and 4×10−6 Torr oxygen was studied. The surface alloys were fabricated by implantation of 25 keV Cr ions into the outermost 300Å of polycrystalline iron samples. The oxide thickness as a function of oxygen exposure was obtained using proton-excited X-ray analysis, and composition profiles of oxide films were obtained using Auger electron spectroscopy and ion sputtering. The addition of Cr to Fe by surface and bulk alloying caused the oxidation rate to decrease and changed the oxidation kinetics from parabolic (for Fe) to logarithmic (for Cr concentrations ≥4.7at.%). Interpretation of the data in terms of simple oxidation theories indicates that the Cr additions may reduce the oxidation rate by altering the electronic properties of the metal-oxide interface.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00603672
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  • 57
    Digitale Medien
    Digitale Medien
    Oxidation of Fe-C alloys at 700°C (1979)
    Springer
    Oxidation of metals 13 (1979), S. 255-272 
    Details
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; Fe-C ; graphite deposition ; nonadherent oxide ; kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation of Fe-C alloys containing 0.5 and 1.0% C was studied in 1 atm O2 at 700° C. The oxidation rate is considerably slower than for pure Fe. The oxide scale formed is detached, multilayered, and overoxidized, containing little or no FeO. A thin film of graphite was identified at the metal-oxide interface by electron diffraction. It is proposed that the slow oxidation and abnormal scale are caused by a residue of graphite left at the metal surface from the oxidation of Fe3C. This inhibition of the oxidation of Fe by carbon at 700°C is in contrast to the stimulation observed at 500°C.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00603670
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  • 58
    Digitale Medien
    Digitale Medien
    Kinetics interpretation of NiO electrical conductivity under low oxygen pressures (1979)
    Springer
    Oxidation of metals 13 (1979), S. 301-309 
    Details
    ISSN: 1573-4889
    Schlagwort(e): NiO ; Electrical conductivity ; gas-solid equilibria ; kinetics ; equivalent circuit
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract In a previous work it has been stated that the NiO electrical conductivity changes connected to the oxygen pressure changes may be considered as a transitory phenomenon. A mixed kinetics case controlled by the formation of surface cation vacancies and their diffusion in the bulk is proposed to explain the reaction process. By means of an equivalent electrical circuit in good agreement with the kinetics model it was possible to reproduce the experimental phenomenon.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00609302
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  • 59
    Digitale Medien
    Digitale Medien
    Kinetics and mechanism of high-temperature sulfur corrosion of Fe-Cr-Al alloys (1979)
    Springer
    Oxidation of metals 13 (1979), S. 481-504 
    Details
    ISSN: 1573-4889
    Schlagwort(e): kinetics ; sulfidation ; Fe-Cr-Al alloys
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The influence of aluminium on the kinetics and mechanism of high-temperature sulfidation of Fe-Cr alloys containing 20 at.% chromium has been investigated. It has been found that the addition of aluminum greatly improves the scaling resistance of Fe-Cr alloys against attack by sulfur vapors at high temperatures.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00812774
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  • 60
    Digitale Medien
    Digitale Medien
    The oxidation behavior of a Zr-0.5Y alloy (1975)
    Springer
    Oxidation of metals 9 (1975), S. 357-365 
    Details
    ISSN: 1573-4889
    Schlagwort(e): kinetics ; zirconia ; defect structure ; ionic conductivity ; yttria dopant
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract A Zr-0.5 Y alloy was found to oxidize about 6 times faster than pure zirconium over the temperature range of 400 to 565°C. The activation energies were nearly identical (∼32 kcal/mole). The activation energies correspond to grain boundary diffusion of oxygen through the scale. The higher oxidation rate of the alloy was attributed to a higher anion vacancy concentration and the assumption that diffusion sites in the lattice and boundaries were in local equilibrium. Measurements on yttria-doped zirconia showed that ionic conductivity was increased markedly by yttrium and extended over a wide range of oxygen pressure. The defect structure of the doped oxide was changed to one of oxygen vacancies, even at the high end of the oxygen pressure range, 10−8 to 0.2 atm, over which pure ziconia contains oxygen interstitials. The doped oxide was found to be extrinsic over the entire range of oxygen pressure and, although ionic conductivity predominated, electronic conductivity was still appreciable. The electronic conductivity, however, was still sufficiently high so that electron transport was not rate-controlling in the predominantly ionic-conducting scale.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00613535
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  • 61
    Digitale Medien
    Digitale Medien
    Relating Single-Impact Events to Macrokinetic Features in Mechanical Alloying Processes (2000)
    Springer
    Journal of materials synthesis and processing 8 (2000), S. 271-277 
    Details
    ISSN: 1573-4870
    Schlagwort(e): Comminution ; kinetics ; mechanical alloying ; phase transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract It has been shown that structural evolution occurring in powder mixtures subjected to mechanical treatment by milling follow well-defined conversion trends as a function of milling time. Sigmoidal curves were observed in the case of the mechanical alloying of transition metal mixtures, whereas a simpler kinetic course with a progressively decreasing transformation rate was found to characterize the disordering process of intermetallic equilibrium compounds by mechanical milling. Under the stipulation that collisions are the dominant energy transfer events, a kinetic model is developed to relate the observed macrokinetic features to the discrete powder fractions, which transform at each impact. Because of its intrinsic qualities, the milling process was regarded as discrete processing. A statistical approach was followed to work out a set of differential equations, solutions of which provide a sound description of the transformation kinetics in terms of conventional rate expressions. The model allows one to reproduce the different kinetic behaviors by means of a single, unifying mathematical formalism. Furthermore, quantifying the structural evolution rate by suitable kinetic constants permits the exploration of the reactive behavior of a system treated under different milling regimes or to compare, on an absolute basis, different systems processed under similar conditions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1011382008963
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  • 62
    Digitale Medien
    Digitale Medien
    High-temperature oxidation of SiC in a glow-discharge oxygen plasma (1976)
    Springer
    Oxidation of metals 10 (1976), S. 97-103 
    Details
    ISSN: 1573-4889
    Schlagwort(e): silicon carbide ; oxidation ; molecular oxygen ; glow-discharge oxygen plasma ; kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation kinetics and structure of the oxide scales formed on high-density SiC were studied in molecular oxygen at 740 Torr and in a glow-discharge oxygen plasma at 0.1 Torr at temperatures of 1000, 1100, and 1200°C. The monatomic oxygen formed by the glow discharge markedly increased the reaction rate and the vaporization of some of the oxidation products. The marked differences in kinetics suggest that the rate-controlling step during oxidation in molecular oxygen is the dissociation of adsorbed diatomic oxygen to the monatomic species. Films formed in molecular oxygen were mostly amorphous SiO2 with small inclusions of SiC and graphite, whereas films formed in dissociated oxygen were primarily amorphous SiO2 containing SiO, S2O3, and the coesite form of SiO2.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00614239
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  • 63
    Digitale Medien
    Digitale Medien
    Oxidation of an Fe—19 wt. % Ni alloy in CO2 at 700–1000°C (1978)
    Springer
    Oxidation of metals 12 (1978), S. 215-225 
    Details
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; Fe-Ni alloys ; kinetics ; scale morphology ; EPMA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation of an Fe—19.34 wt. % Ni alloy in dry CO2 has been studied at 700—1000°C using thermogravimetry, metallography, and EPMA. Weight gains for oxygen consumption followed a linear-parabolic-linear sequence at all temperatures. During the initial linear stage the scale consisted mainly of magnetite and the activation energy of 133±25 kJ · mole−1 is considered to be due to dissociation of CO2 into CO and adsorbed oxygen on the outer magnetite surface. During the parabolic oxidation stage a continuous Ni-rich layer containing ∼ 70% Ni forms a barrier to the diffusion which has an activation energy of 192±79 kJ · mole−1. The breakdown of the barrier layer causes a return to linear kinetics with an activation energy of 138±42 kJ · mole−1 for dissociation of CO2 on the outer surface. During the final linear stage there is pronounced general and intergranular subscale formation. Detailed information is presented of the Ni redistribution and concentrations during oxidation and its correlation with the kinetics and morphology.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00616097
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  • 64
    Digitale Medien
    Digitale Medien
    High-Temperature Oxidation Behavior of the Co-Base Superalloy DZ40M in Air (2000)
    Springer
    Oxidation of metals 53 (2000), S. 351-360 
    Details
    ISSN: 1573-4889
    Schlagwort(e): Co-base superalloy ; high-temperature oxidation ; kinetics ; structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation behavior of the Co-base superalloy DZ40M was studied in air at900–1100°C for times of up to 2000 hr. The results indicated thatthis alloy can grow a protective oxide scale at 900 and 1000°C duringisothermal oxidation, but not at 1100°C because of serious cracking andspalling of the oxide scales. Moreover, an internal-precipitate zone formedin the subsurface region of the alloy at all temperatures and times. Theprecipitates were rich in Cr in the vicinity of the alloy–scaleinterface and rich in Al deep in the alloy. The internal-precipitatemorphology changed from a granular to needlelike shape with increasingoxidation temperature.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1004597405809
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  • 65
    Digitale Medien
    Digitale Medien
    Kinetics of the oxidation of ilmenite (1975)
    Springer
    Oxidation of metals 9 (1975), S. 99-116 
    Details
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; kinetics ; ilmenite ; rutile ; pseudobrookite
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation of ilmenite (FeTiO3) in air and dry oxygen was investigated over the temperature interval 600 to 970°C. Dense platelets of ilmenite crystals as well as powder samples of ilmenite were oxidized. The weight data were recorded employing a thermobalance. The oxidation kinetics of ilmenite platelets were parabolic except for the initial stages during which logarithmic kinetics were observed. For powder samples the logarithmic rate law was followed primarily. The logarithmic rate law was attributed to free penetration of oxygen through cracks and short-circuit paths. The activation energies associated with the logarithmic rate law were nearly one-half of those obtained from parabolic oxidation. The growth morphology of the products of oxidation of ilmenite was observed with a scanning electron microscope. The effect of growth morphology on the kinetics is discussed, and a probable reaction mechanism is suggested for the oxidation of ilmenite.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00613496
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  • 66
    Digitale Medien
    Digitale Medien
    A rapid method for determining parabolic rate constants of metal oxidation as a function of temperature and oxidant pressure (1975)
    Springer
    Oxidation of metals 9 (1975), S. 441-450 
    Details
    ISSN: 1573-4889
    Schlagwort(e): kinetics ; cobalt and nickel oxidation ; parabolic rate constant
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract A new fast method is proposed for the determination of parabolic rate constants of metal oxidation as a function of pressure and temperature. The method consists of determining rate constants by oxidation of a single metal sample in a continuous manner, periodically changing the oxidant pressure or temperature. This method eliminates a number of errors inherent in the classical method which involves the use of a new metal specimen in each experiment and it further shortens the time of evaluating the functions k p '' = f (p, T). The method is particularly suitable for the determination of rate constants of slow processes. To verify the proposed method measurements of the kinetics of oxidation of cobalt and nickel at different oxygen pressures over the temperature range 1000–1300° C were carried out.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00611692
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  • 67
    Digitale Medien
    Digitale Medien
    Theoretical study of heterogeneous reaction kinetics: A comparison between microcalorimetric and thermogravimetric curves (1976)
    Springer
    Oxidation of metals 10 (1976), S. 105-111 
    Details
    ISSN: 1573-4889
    Schlagwort(e): kinetics ; oxidation ; microcalorimetry ; thermogravimetry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract In the kinetic theories of Bodenstein or Semenov the expression for the rate of a chemical reaction with several elementary stages can be expressed by different physical parameters. If two experimental methods are used, one method of necessity being microcalorimetry to measure the thermal flux produced by the reaction, it is possible to distinguish a pure kinetics case from a mixed one. The two-method technique has been verified by a study of the oxidation of niobium.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00614240
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  • 68
    Digitale Medien
    Digitale Medien
    The interaction of titanium and titanium alloys with nitrogen at elevated temperatures. I. The kinetics and mechanism of the titanium-nitrogen reaction (1976)
    Springer
    Oxidation of metals 10 (1976), S. 41-67 
    Details
    ISSN: 1573-4889
    Schlagwort(e): titanium ; nitridation ; kinetics ; diffusion ; scaling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The nitridation behavior of titanium has been examined in an atmosphere of nitrogen over the temperature range 900–1000° C. In addition to determining the reaction kinetics, microhardness and metallographic studies have been carried out on the nitrided substrates and nitride scales. Overall parabolic kinetics were exhibited, while a linear scaling reaction (associated principally with Ti2N formation) was observed. Extensive dissolution of nitrogen in the substrate was evident from the microhardness studies, and at 950 and 1000° C the growth of the nitrogen-stabilized αTi phase layer followed a parabolic law. Consideration of all the observed processes and derived data suggested that diffusion of nitrogen in the metal substrate was probably the rate-controlling mechanism.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00611698
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  • 69
    Digitale Medien
    Digitale Medien
    Studies of the kinetics of nickel sulfidation in H2S-H2 mixtures in the temperature range 450–600°C (1977)
    Springer
    Oxidation of metals 11 (1977), S. 263-276 
    Details
    ISSN: 1573-4889
    Schlagwort(e): nickel ; sulfidation ; kinetics ; mechanism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The reaction between pure nickel and H2S-H2 mixtures containing 1–65% H2S has been studied over the temperature range 450–600°C. The sulfidation of nickel in the temperature range 560–600°C has been found to follow a linear rate law at low concentrations of H2S and a parabolic rate law at higher concentrations (10% and 65% H2S); X-ray examination of the scale formed on the metal showed it to be almost entirely β-Ni3S2. On the basis of the kinetics and marker studies it can be concluded that the sulfide scale on nickel is formed by the outward transport of the metal and the inward transport of sulfur. In the temperature range 450–500°C the sulfidation of nickel follows a parabolic rate law. In mixtures containing 10% H2S the scale formed contains voids, the occurrence of which is connected with formation of Ni7S6. It has also been shown that the rate of transport through the Ni3S2 layer has an essential influence on the formation of a continuous layer of Ni7S6. Marker studies have shown that both nickel and sulfur appear to be mobile in β′-Ni3S2.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00606061
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  • 70
    Digitale Medien
    Digitale Medien
    Oxidation of Fe-C alloys at 500°C (1978)
    Springer
    Oxidation of metals 12 (1978), S. 67-82 
    Details
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; Fe-C ; kinetics ; oxide grain size ; grain-boundary diffusion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Fe-C alloys containing 0.1, 0.5, and 1.0% C were oxidized in 1 atm O2 at 500°C. Two specimen preparations were used: annealed followed by slow cooling to form coarse pearlite plus proeutectoid ferrite or cementite; and cold-worked by abrading after annealing. The cold-worked alloys oxidize more rapidly. Annealed pearlite oxidizes faster than annealed ferrite. The differences in oxidation rate are caused by differences in the Fe3O4 grain size, that is, by the number of oxide grain boundaries available to act as easy diffusion paths for the outward diffusion of Fe through the Fe3O4. The oxidation rate constant is 10 times larger for fine-grained poly crystalline oxide than for oxide in which the Fe3O4 is monocrystalline.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00609975
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  • 71
    Digitale Medien
    Digitale Medien
    Low-temperature oxidation of Fe-24 wt.%Cr (1979)
    Springer
    Oxidation of metals 13 (1979), S. 437-456 
    Details
    ISSN: 1573-4889
    Schlagwort(e): Fe-Cr ; oxidation ; kinetics ; oxide morphology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Ferritic polycrystalline Fe-24 wt.% Cr was oxidized in pure oxygen at 190 ≤ T≤490° C and pressures in the range 5.3×10−2–13.3 Pa for periods of up to 5 hr. The reaction proceeded in three stages. An initial period of accelerating rate was accompanied by oxide island nucleation and growth. Following island coalescence the rate was approximately logarithmic at low temperatures and somewhat slower than parabolic at high temperatures. Rate control during this period was thought to be due to mass transport through the oxide grain boundaries left by the island impingement process. During these first two stages the oxide formed was γ-M2O3 with possibly some spinel. The final stage of reaction involved the appearance of α-M2O3 on the outer oxide surface and a substantial slowing of the oxidation rate due to the low diffusivity in this phase.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00605109
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  • 72
    Digitale Medien
    Digitale Medien
    Solid-solid reactions, II: Mechanism of barium metatitanate synthesis (1979)
    Springer
    Oxidation of metals 13 (1979), S. 89-104 
    Details
    ISSN: 1573-4889
    Schlagwort(e): BaTiO3 ; kinetics ; solid state ; mechanisms
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The authors propose a mechanism for the solid-solid reaction BaCO3+ TiO2→BaTiO3+CO2. This mechanism is based on the real structure of the present semiconductors. The reactions at different interfaces and the diffusing species are identified. The reaction rates are calculated and the dependence of the reaction rate upon O2, N2, and CO2 gas pressure is interpreted and discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00715872
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  • 73
    Digitale Medien
    Digitale Medien
    Oxidation of high-chromium Ni-Cr alloys (1979)
    Springer
    Oxidation of metals 13 (1979), S. 119-158 
    Details
    ISSN: 1573-4889
    Schlagwort(e): nickel-chromium alloys ; oxidation ; high temperature ; kinetics ; mechanisms
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation of binary Ni-Cr alloys containing 44 and 50 wt. % Cr has been studied over a range of oxygen partial pressures at temperatures between 800 and 1100°C. The effects of cold work, surface preparation, and distribution of the Cr-rich second phase have been studied. The oxidation behavior is complex and cannot be described by a single model. The oxide grows by short-circuit diffusion as well as bulk transport through Cr 2 O 3 scales. The scale-growth mechanism includes extensive metal-oxide separation requiring Cr vapor transport to the scale, compressive stresses within the oxide which result in scale bulging and cracking, and the formation of a second oxide layer which results in voids being incorporated into the scale. Any factor which reduces the oxide grain size, such as cold work, finer distribution of the Cr-rich α phase or reduced oxygen pressure, results in an increased oxidation rate of binary alloys because of an increased number of grain-boundary short-circuit diffusion paths.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00611976
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  • 74
    Digitale Medien
    Digitale Medien
    Analysis of Aluminum—Yeast Hexokinase Interaction: Modifications on Protein Structure and Functionality (2000)
    Springer
    The protein journal 19 (2000), S. 199-208 
    Details
    ISSN: 1573-4943
    Schlagwort(e): Aluminum ; yeast hexokinase ; preferential interactions ; kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The aluminum and yeast hexokinase interaction was studied. Structural changes were correlated with variations in protein functionality. Results show two different behaviors: At low metal concentrations preferential adsorption of metal (and water exclusion) induces aggregate formation. No significant changes in the protein structure occur, but there is a continuous loss of activity (from the first concentration). At large salt concentrations a monomerization process and a conformational change in the secondary structure as well as in the three-dimensional structure take place. This change reduces the percentage of α-helix conformation, gives thermal stability to the protein, and allows the exposure of some tryptophan residue and hydrophobic regions. The protein inhibition increases. Conformational change and monomerization may allow access of the metal to the substrate site, mainly the ATP site. The inhibition in any case is of mixed type with a competitive component.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007055719926
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  • 75
    Digitale Medien
    Digitale Medien
    A Comparative Study of Human Muscle and Brain Creatine Kinases Expressed in Escherichia coli (2000)
    Springer
    The protein journal 19 (2000), S. 59-66 
    Details
    ISSN: 1573-4943
    Schlagwort(e): Creatine kinase ; human ; expression ; brain ; muscle ; purification ; kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract We report the expression of the human muscle (CK-MM) and brain (CK-BB) creatine kinases in Escherichia coli. The proteins have been purified to apparent homogeneity and several of their physical and kinetic properties investigated. In the process, we have conclusively verified the correct DNA sequence of the genes encoding the respective isozymes, and determined the correct primary structure and mass of the gene products. Alignment of the primary sequences of these two enzymes shows 81% sequence identity with each other, and no obvious gross structural differences. However, Western blot analyses demonstrated the general lack of antigenic cross-reactivity between these isozymes. Preliminary kinetic analyses show the K m and k cat values for the creatine and MgATP substrates are similar to values reported for other isozymes from various tissues and organisms. The human muscle and brain CKs do not, however, exhibit the synergism of substrate binding that is observed, for example, in rabbit muscle creatine kinase.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007047026691
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  • 76
    Digitale Medien
    Digitale Medien
    Immunocytochemical localization of vasotocin and mesotocin in the hypothalamus of lacertilian reptiles (1979)
    Springer
    Cell & tissue research 200 (1979), S. 223-227 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Hypothalamus ; Lacertilian reptiles ; Vasotocin neurons ; Mesotocin neurons ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The hypothalamic magnocellular neurosecretory system of lizards was studied with the unlabeled antibody peroxidase-antiperoxidase complex (PAP) technique at the light microscopic level. It was shown that vasotocin and mesotocin are synthesized in separate neurons. The vasotocinergic as well as the mesotocinergic perikarya are of different sizes. Both cell types occur in close juxtaposition, but without a distinct pattern of distribution. The external zone of the lacertilian median eminence contains numerous immunoreactive vasotocinergic fibers and only few immunoreactive mesotocinergic fibers. The general organization of the hypothalamic magnocellular neurosecretory system of lizards, as revealed by immunocytochemistry, is essentially similar to that revealed with unspecific staining methods.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00236415
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  • 77
    Digitale Medien
    Digitale Medien
    Electron microscopical-immunocytochemical evidence of ecdysteroids in the prothoracic gland of Galleria mellonella (1979)
    Springer
    Cell & tissue research 200 (1979), S. 285-290 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Immunocytochemistry ; Ecdysteroids ; Prothoracic gland ; Insect hormones ; Galleria mellonella
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Fixation of prothoracic glands of Galleria mellonella with a solution containing saponin permits immunocytochemical staining of the entire gland. By this means ecdysteroids were demonstrated electron microscopically to be present in the hyaloplasm and microtubules.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00236420
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  • 78
    Digitale Medien
    Digitale Medien
    Immunocytochemical identification of enkephalinergic neurons in the hypothalamic magnocellular preoptic nucleus of the goldfish, Carassius auratus (1979)
    Springer
    Cell & tissue research 200 (1979), S. 147-151 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Enkephalin neurons ; Vasotocin neurons ; Isotocin neurons ; Immunocytochemistry ; Goldfish (Carassius)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Our immunocytochemical investigation of the magnocellular neuroendocrine system in the goldfish hypothalamus reveals enkephalin (ENK)-containing neurons interspersed among the vasotocin (VT)- and isotocin (IT)-containing neurons of the preoptic nucleus. The perikarya of the ENK, VT, and IT neurons do not show distinct morphological differences at the level of light microscopy and are not located preferentially within the nucleus. Separate ENK, VT and IT fibers course laterally and ventrally through the hypothalamus as they descend toward the pituitary gland. All three fiber types form terminals around blood vessels in the neurohypophysis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00236894
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  • 79
    Digitale Medien
    Digitale Medien
    Immunoreactive pancreatic polypeptide (PP) occurs in the central and peripheral nervous system: Preliminary immunocytochemical observations (1979)
    Springer
    Cell & tissue research 200 (1979), S. 179-186 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Pancreatic polypeptide (PP) ; Neurones ; Central nervous system ; Peripheral nervous system, gut ; Immunocytochemistry ; Mammals ; Birds
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Pancreatic polypeptide (PP) is a candidate hormone of unknown physiological significance. It is produced by a population of endocrine cells in the pancreas. In the present study a PP-like peptide was found to occur in the mammalian and avian central and peripheral nervous systems. Immunoreactive nerve fibres and nerve cell bodies were widely distributed in the brain. Dense accumulations of nerve fibres occurred in the following areas: nucleus accumbens, interstitial nucleus of the stria terminalis, para- and periventricular hypothalamic nuclei, and medial preoptic area. In addition, nerve fibres were regularly seen in cortical areas. Immunoreactive perikarya were observed in the following regions: cortex, nucleus accumbens, neostriatum and septum. In the gut, immunoreactive nerve fibers were distributed in the myenteric plexus, in smooth muscle, around blood vessels, and in the core of the villi. Immunoreactive perikarya occurred in the submucosal and myenteric plexus, suggesting that PP immunoreactive nerves are intrinsic to the gut. In the species examined, the neuronal PP-like peptide could be demonstrated with an antiserum raised against avian PP, but not with those raised against bovine or human PP. Thus, neuronal PP is distinct from the PP that occurs in pancreatic endocrine cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00236410
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  • 80
    Digitale Medien
    Digitale Medien
    Autoradiographic studies of 3H-dexamethasone uptake by immunocytochemically characterized cells of the rat pituitary (1977)
    Springer
    Cell & tissue research 182 (1977), S. 347-356 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Pituitary ; Dexamethasone ; ACTH ; Autoradiography ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary 3H-Dexamethasone (10 μg/kg) was injected intravenously in adrenalectomized rats and after survival times of 5, 30, 60, and 180 min its uptake within the pituitary was studied by autoradiography. Radioactivity was concentrated in cell nuclei in the pars nervosa and pars distalis. Within the pars intermedia, only cells of the marginal zone were labeled. In the pars distalis, some cells showed a weak nuclear accumulation of radioactivity as early as 5 min after injection. The tissue radioactivity was nearly maximal at 5 min, and the proportion of radioactivity in nuclei reached a maximum of 60–70% by 30 min. In competition experiments, non-radioactive steroids (1 mg/kg) were injected 5 min before 3H-dexamethasone and sacrifice was 30 min later. Dexamethasone markedly diminished the nuclear accumulation in the pars distalis, but corticosterone and progesterone did not. In the pars nervosa, corticosterone and progesterone competed for nuclear uptake of 3H-dexamethasone, although less effectively than dexamethasone itself. Different cell types in the pars distalis were characterized by treating autoradiograms with an immuno-peroxidase bridge procedure. Cells treated with anti-ACTH 17–39 had the greatest nuclear concentration of radioactivity, and those stained with anti-TSH were least heavily labeled. Cells treated with antisera to GH, PRL, and hCG were moderately labeled.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00219770
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  • 81
    Digitale Medien
    Digitale Medien
    Ultrastructural characterization by ruthenium red of the surface of the fat globule membrane of human and rat milk with data on carbohydrates of fractions of rat milk (1975)
    Springer
    Cell & tissue research 157 (1975), S. 17-24 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Milk ; Fat globule membrane ; Carbohydrates ; Chemistry ; Ruthenium red ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The fat globules of the cream fractions of human and rat milk were stained with ruthenium red. Under the electron microscope, discrete granules and an amorphous coat of lesser density are seen at the surface of the milk fat globules. Since ruthenium red binds anionic groups selectively, it is probable that the granules containe the greatest concentration of these groups. The cream fraction of rat milk contains hexoses, hexosamines, methylpentoses and sialic acid. Methylpentoses and hexosamines are significantly enriched in the cream fraction. It is concluded that the finding of a surface coat in milk fat globules is in keeping with the Bargmann-Knoop model and suggests a distinct mechanism for carrying certain complex carbohydrates in milk. The role of the negative charges at the outer surface of the membrane coat in maintaining fat globules in suspension and in binding certain cations such as calcium is suggested.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00223228
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  • 82
    Digitale Medien
    Digitale Medien
    Electron microscopic immunocytochemical demonstration of separate neurophysin-vasopressinergic and neurophysin-oxytocinergic nerve fibres in the neural lobe of the rat hypophysis (1976)
    Springer
    Cell & tissue research 171 (1976), S. 31-37 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Rat posterior pituitary ; Neurophysin-vasopressinergic and neurophysin-oxytocinergic fibres ; Immunocytochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary By means of the unlabeled antibody peroxidase-antiperoxidase (PAP) technique at the electron microscopic level, it was demonstrated that the hormones of the neural lobe of the rat hypophysis are located in separate neurophysin-vasopressinergic and neurophysin-oxytocinergic nerve fibres. These observations confirm the results of our previous immunocytochemical studies at the light microscopic level.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00219698
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  • 83
    Digitale Medien
    Digitale Medien
    Growth hormone-release inhibiting hormone (GH-RIH) pathway of the rat hypothalamus revealed by the unlabeled antibody peroxidase-antiperoxidase method (1975)
    Springer
    Cell & tissue research 160 (1975), S. 423-430 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Growth hormone-release inhibiting hormone ; Somatostatin ; Hypothalamus ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Utilizing the unlabeled antibody enzyme method, we investigated the distribution of hypothalamic elements immunoreactive with antibodies to growth hormonerelease inhibiting hormone (GH-RIH). Immunostained elements, resembling neural processes, are distributed along a pathway corresponding to a portion of the tuberoinfundibular tract. However, GH-RIH fibers are caudal, dorsal and medial to LH-RH fibers detected by the same technique. Similar topographic arrangements are noted in coronal and sagittal sections. Comparable results were obtained with two different preparations of antisera to GH-RIH. No cell bodies specifically stained by anti-GH-RIH were detected. Our data agree with those of other investigators using immunohistochemical techniques.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00225761
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  • 84
    Digitale Medien
    Digitale Medien
    Quantitative autoradiographic assessment of 3H-estradiol uptake in immunocytochemically characterized pituitary cells (1976)
    Springer
    Cell & tissue research 166 (1976), S. 25-35 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Pituitary gland ; Cell types ; Estrogen ; Autoradiography ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Dry-mount autoradiography was combined with peroxidase immunocytochemistry to examine estrogen uptake in four pituitary cell types. Quantification by silver grain counts was used to compare 3H-estradiol uptake in nuclei of pituitary cells 60 min after i.v. injection into short-term (control) and long-term ovariectomized and in long-term thyroidectomized rats. Under all three hormonal states, the order of labeling intensity was: gonadotropes 〉 somatotropes 〉 lactotropes 〉 thyrotropes. Long-term ovariectomy caused a significant increase in estrogen uptake of gonadotropes, somatotropes and lactotropes, while uptake in thyrotropes decreased. Long-term thyroidectomy decreased uptake in somatotropes, lactotropes and thyrotropes while gonadotropes remained unchanged.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00215122
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  • 85
    Digitale Medien
    Digitale Medien
    Immunocytochemical localization of nerve growth factor (NGF) in the submandibular gland of adult mice by light and electron microscopy (1976)
    Springer
    Cell & tissue research 169 (1976), S. 289-299 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Nerve growth factor ; Submandibular gland mice ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Nerve growth factor (NGF) was localized in the submandibular gland of adult male mice by a direct immunocytochemical method using highly purified antibodies against NGF coupled to horseradish peroxidase. In light microscopic sections the reaction product was entirely confined to the cells of the secretory tubules. The acinar part of the gland was free of reaction product. This finding was confirmed by electron microscopy. Within the cells NGF was localized exclusively in the apical secretory granules. No reaction was observed in the rough endoplasmic reticulum, the Golgi region or in the granules of the basal part of the cells. This observation favours the assumption that NGF is derived from a precursor molecule and that the precursor is transformed into immunologically active NGF within the secretory granules during their transport from the basal to the apical part of the tubular cells. Stimulation of the submandibular gland with carbachol (2 mg/kg) led to a massive release of the content of the secretory granules, including NGF, into the salivary duct.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00219602
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  • 86
    Digitale Medien
    Digitale Medien
    Ultrastructural immunocytochemical localization of luteinizing hormone-releasing hormone (LH-RH) in the median eminence of the guinea pig (1976)
    Springer
    Cell & tissue research 169 (1976), S. 157-166 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Luteinizing hormone-releasing hormone ; Median eminence ; Electron microscopy ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary LH-RH was localized at the ultrastructural level in axons and nerve terminals of the median eminence of the male guinea pig. LH-RH positive neuronal profiles were most concentrated in the medial-dorsal aspect of the infundibular stalk and in the post-infundibular median eminence at the level immediately following separation of the stalk from the base of the brain. LH-RH containing axon profiles were most abundant in the palisade zone; nerve terminals in contact with the hypophysial portal vasculature were relatively rare. The hormone was present within granules that measured 900–1,200 Å in axons of the palisade zone and 400–800 Å in nerve terminals abutting on the portal plexus. The differently sized granules represent heterogeneous populations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00214205
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  • 87
    Digitale Medien
    Digitale Medien
    Cell differentiation of the fetal rat anterior pituitary in vitro (1976)
    Springer
    Cell & tissue research 170 (1976), S. 263-273 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Fetal pituitary ; Cell differentiation ; Immunocytochemistry ; Tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Adenohypophysial primordia of rat embryos at 13 to 15 days gestation were cultured in Parker 199 synthetic medium for 2 to 11 days. At the end of the culture period their fine structure and the presence of immunoreactive trophic hormones using the peroxidase-labeled antibody technique were investigated. The degree of differentiation in the glands depends largely on the age of the embryos furnishing the explants. Cultured pituitaries explanted on the 13th day of gestation contain only ACTH-positive cells and about 15% of the cells are granular. The granules are 50–100 nm in diameter in some cells, while in other cells they range from 50 to 200 nm. In cultivated adenohypophysial primordia of embryos on the 15th day of intrauterine life ACTH, prolactin, LH and TSH cells are evident, but only the same two kinds of granular cells can be observed with the electron microscope. The extent of cytodifferentiation in the glands explanted on the 14th day of gestation is intermediate between the two other groups. The data suggest that the fetal rat pituitary has the capacity of self-differentiation but to a lesser extent than that of the in situ hypophysis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00224303
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  • 88
    Digitale Medien
    Digitale Medien
    Ultrastructural immunocytochemical localization of neurophysin and vasopressin in the median eminence and posterior pituitary of the guinea pig (1975)
    Springer
    Cell & tissue research 159 (1975), S. 291-301 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Neurophysin ; Vasopressin ; Median eminence ; Electron microscopy ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary With the use of tissue prepared by freeze-substitution and the unlabelled antibody enzyme technique, neurophysin and vasopressin were localized at the ultrastructural level in the posterior pituitary and median eminence of the guinea pig. In the posterior pituitary neurophysin was found in the large neurosecretory granules (1300–1500 Å) of axons, Herring bodies, and nerve terminals. In some of these axons immunoreactive neurophysin was found outside of granules in the axoplasm. By light microscopy neurophysin was found in both the zona interna and zona externa of the median eminence; this was confirmed by electron microscopy. In the zona interna as in the posterior pituitary, neurophysin was localized both inside and outside the large neurosecretory granules. In the zona externa, immunoreactive deposit was primarily located in granules with a diameter of 900–1100 Å in nerve terminals abutting on the primary portal plexus. The distribution of vasopressin paralleled that of neurophysin except that the hormone was rarely extragranular. These results demonstrate for the first time that both neurophysin and vasopressin are present in granules of axons that are in contact with the hypophysial portal vasculature.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00221777
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  • 89
    Digitale Medien
    Digitale Medien
    Ontogeny of the pig hypothalamic neurosecretory system with particular reference to the distribution of neurophysin (1975)
    Springer
    Cell & tissue research 164 (1975), S. 543-557 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Magnocellular hypothalamic nuclei ; Fetal and neonatal pigs ; Anti-porcine neurophysin serum ; Immunocytochemistry ; Slab gradient polyacrylamide gel electrophoresis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The immunoperoxidase cytochemical reaction was applied to the localization of neurophysin-containing elements in the fetal and adult pig hypothalamus. In the 60 day fetal pig, cells of the supraoptic nucleus (SON) were the only structures in the hypothalamus in which neurophysin was detected. However, by 87 days the cell bodies in both the SON and paraventricular nucleus (PVN) contained neurophysin-like material. The distribution of immunoreactive material in the 111 day fetal animal was similar to that found in the adult pig. In transverse section of the mature pig the SON exists in two discrete components; an antero-lateral group of cells connected by scattered cells to a smaller postero-medial group. Anteriorly, the PVN appears as a line of cells bordering the third ventricle but as we proceed posteriorly the dorsal aspect expands laterally to give a wedge-shaped group of cells. In mid-sagittal sections, the cells of the PVN are distributed over a wide area of the anterior hypothalamus in a triangular profile. The borders between the SON and PVN became more difficult to define in medial sections than in lateral sections. Continuous gradient polyacrylamide gel electrophoresis was carried out on the neural lobe extracts from fetal, newborn and adult pigs. Proteins with an electrophoretic mobility similar to that of porcine neurophysins-I,-II and -III were present in the newborn and 98 day fetal pig. It is concluded that material immunoreactive with anti-neurophysin serum is present in the hypothalamus of the 60 day fetal pig. Furthermore, at late fetal development and during the postnatal period it is tentatively suggested that the neurophysin present in the pituitaries of these animals is chemically identical with that of adult neurophysin.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00219944
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  • 90
    Digitale Medien
    Digitale Medien
    Immunocytochemical demonstration of separate vasotocinergic and mesotocinergic neurons in the amphibian hypothalamic magnocellular neurosecretory system (1976)
    Springer
    Cell & tissue research 175 (1976), S. 289-296 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Amphibian hypothalamus ; Vasotocinergic and mesotocinergic neurons ; Neurophysins ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Using the unlabeled antibody peroxidase-antiperoxidase (PAP) technique at the light microscopic level, it was demonstrated that, in the amphibian magnocellular hypothalamo-hypophysial neurosecretory system, vasotocin and mesotocin are synthesized in separate neurons. A tendency to preferential location of the two kinds of neuronal perikarya is described. The neurosecretory perikarya are the origin of separate vasotocinergic and mesotocinergic axons. In the neural lobe, the pattern of distribution of the two types of axons is different. The coarse ventricular “dendrites” of both kinds of neurons are hormone-containing processes. Staining with anti-bovine neurophysin I serum suggested that the vasotocinergic and the mesotocinergic neurons synthesize different neurophysins.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00218707
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  • 91
    Digitale Medien
    Digitale Medien
    Isolation, characterization and localization of bovine adrenal medullary myosin (1977)
    Springer
    Cell & tissue research 178 (1977), S. 17-38 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Myosin ; Immunocytochemistry ; Adrenal medulla ; Exocytosis ; Secretion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Myosin was isolated in high purity from the bovine adrenal medulla by gel filtration and ion exchange chromatography. The purified myosin was analyzed by electrophoresis in gels containing SDS and found to contain a 200,000 molecular weight heavy chain and major light chains of molecular weights 20,000 and 17,000 in a 1∶1∶1 molar ratio. At high ionic strength the myosin had high Ca-ATPase and K-EDTA-ATPase activities and low Mg-ATPase activity. At low ionic strength, the Mg-ATPase was activated to a low level by rabbit muscle actin. The myosin was found to decorate F-actin in the absence, but not the presence of ATP. In low ionic strength solutions, the myosin assembled into characteristic bipolar filaments. The distribution of this myosin in the adrenal medulla and of cross-reacting myosin in several other bovine tissues was determined with the use of antimedullary myosin immunoglobulin G as a specific stain that was detected by direct and indirect immunofluorescence. In the medulla strong staining was seen between the chords of chromaffin cells indicating the presence of a highly muscular vasculature that may perform functions analogous to those of the myoepithelium of exocrine glands. The chromaffin cells showed weak positive staining around the nuclei and in a pattern radiating toward adjacent blood vessels. Cells of the inner zone of the adrenal cortex showed strong staining in the peripheral cytoplasm while cells in the intermediate and outer zones did not stain. In a blood smear, platelets and the cytoplasm of leukocytes stained strongly while erythrocytes did not stain. In striated muscle and the gray and white matter of the cerebrum only the capillaries and larger vessels stained. In the liver the phagocytic cells bordering vascular sinuses stained strongly while the hepatocytes were separated from one another by a 2 micron trilaminar band possibly representing the microfilament web surrounding the bile canaliculi and associated with junctional complexes. The results suggest that myosin is present in several highly differentiated, non-motile tissue cells where it may play a role in secretion or other specialized functions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00232821
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  • 92
    Digitale Medien
    Digitale Medien
    Separation of Ni, Mn, Co, Cu, Fe and Zn by thin-layer chromatography (1976)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 278 (1976), S. 363-363 
    Details
    ISSN: 1618-2650
    Schlagwort(e): Trenn, von Nickel, Mangan, Kobalt, Kupfer, Eisen, Zink ; Chromatographie, Dünnschicht
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00531101
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  • 93
    Digitale Medien
    Digitale Medien
    Diphenyl thiovioluric acid: A new extractive indicator for iron(II) (1976)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 279 (1976), S. 206-206 
    Details
    ISSN: 1618-2650
    Schlagwort(e): Best. von Eisen(II) mit Diphenylthioviolursäure als Indicator ; Volumetrie ; EDTA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00424113
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  • 94
    Digitale Medien
    Digitale Medien
    Dünnschicht-Chromatographie der Methylolmelamine (1975)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 276 (1975), S. 205-207 
    Details
    ISSN: 1618-2650
    Schlagwort(e): Trenn. von Methylolaminen, Melaminharzen ; Chromatographie, Dünnschicht ; Celluloseschicht
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die Identifizierung der Komponenten in einem Methylolmelamin-Gemisch mittels Dünnschicht-Chromatographie wurde möglich, nachdem die einzelnen Methylolmelamine (Mono-, Di-, Tri-, Tetra-, Penta- und Hexamethylolmelamin) rein dargestellt werden konnten. Aus der zweidimensionalen dünnschichtchromatographischen Entwicklung des Methylolmelamin-Gemisches folgt, daß während der Dauer der Entwicklung keine Änderung der Zusammensetzung des Methylolmelamin-Gemisches stattfindet. Die Chromatographie wurde auf Celluloseschichten mit Butanol/Äthanol/Wasser (4∶1∶2) als Fließmittel und ammoniakalkalischer Silbernitratlösung als Nachweisreagens durchgeführt.
    Notizen: Abstract Identification of the components in a methylolmelamine mixture by thin-layer chromatography was facilitated after obtaining each of the individual methylolmelamines (mono-, di-, tri-, tetra-, penta- and hexamethylolmelamine). By the use of two-dimensional thin-layer chromatography it was noted that no change in the composition of the mixture takes place during the time of Chromatographic development. Separation was achieved on cellulose layers using butanol/ethanol/water (4∶1∶2) as solvent and ammonia-alkaline AgNO3 solution as detection reagent.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00437568
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  • 95
    Digitale Medien
    Digitale Medien
    Beiträge zur titrimetrischen Bestimmung von dimeren Hydroxyaldehyden (1975)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 276 (1975), S. 201-204 
    Details
    ISSN: 1618-2650
    Schlagwort(e): Best. von Glykolaldehyd, Glycerinaldehyd, Hydroxyaldehyden ; Volumetrie ; Dimere
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Es wurden die Möglichkeiten für die titrimetrische Bestimmung von dimerem Glykolaldehyd (Fp: 94–96° C) und dl-Glycerinaldehyd (Fp: 138–141° C) untersucht. Die systematischen Fehler der auf Grund verschiedener funktioneller Gruppen durchführbaren Messungen sind von der Stabilität ihrer cyclischen Halbacetale sowie von den ihrer Depolymerisation folgenden weiteren Gleichgewichten bestimmt. Das aus dem dl-Glycerinaldehyd gebildete Halbacetal besitzt höhere Stabilität als dasjenige aus dem Glykolaldehyd. Mit der Hydrogensulfit-Methode werden 95–96%, mit der Hydroxylamin-Methode dagegen 98–99% vom wahren Wert gefunden. In Wasser gelöst zersetzt sich der Glykolaldehyd verhältnismäßig rasch, und das Gleichgewicht kann durch beide Aldehydreaktionen quantitativ gegen die Monomerenform verschoben werden. Unsere Untersuchungen ergaben, daß die Hydroxylamin-Methode zur Bestimmung der in Form cyclischer Halbacetale kristallisierenden, dimeren Hydroxyaldehyde Vorteile gegenüber der Hydrogensulfit-Methode bietet.
    Notizen: Abstract Possibilities for the titrimetric determination of dimeric glycolaldehyde (m.p. 94–96° C) and dl-glyceraldehyde (m.p. 138–141° C) have been investigated. The systematic errors based on different functional groups depend on the stability of the cyclic semiacetals and on the subsequent equilibria established after their depolimerisation. The semiacetal of dl-glyceraldehyde is more stable than that of glycolaldehyde. 95–96% and 98–99% of the real content were found by the hydrogensulphite and hydroxylamine methods, respectively. Glycolaldehyde decomposes rather quickly in aqueous solution and the equilibrium can be shifted towards the monomeric form by both the aldehyde reactions. The hydroxylamine method proved to be more advantageous for the determination of the dimeric hydroxyaldehydes, which cristallise in the form of cyclic semiacetals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00437567
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  • 96
    Digitale Medien
    Digitale Medien
    Titrimetric determination of mercaptans with trivalent cobalt (1976)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 278 (1976), S. 128-128 
    Details
    ISSN: 1618-2650
    Schlagwort(e): Best. von Mercaptanen mit Kobalt(III) ; Volumetrie
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00432575
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  • 97
    Digitale Medien
    Digitale Medien
    Assay of mixtures of hydrazine and other nitrogen bases by thermometric titrimetry (1976)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 280 (1976), S. 373-376 
    Details
    ISSN: 1618-2650
    Schlagwort(e): Best. von Hydrazin, Ammoniak, Anilin, Hydroxylamin, Thiocyanat, Dimethylhydrazin im Gemisch ; Volumetrie ; thermometrisch
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Summary Binary mixtures of hydrazine and one of the following N-containing bases: ammonia, aniline, hydroxylamine, thiocyanate and unsymmetrical dimethyl hydrazine have been assayed thermometrically. The titrations are based both on the basic and the reducing properties of the compounds. For example, whilst for mixtures of hydrazine and ammonia, the total base content is determined by an acid/base titration, and the hydrazine component is determined by oxidation with bromate ion; for mixtures containing aniline or hydroxylamine, serial titration with bromate ensures that all the hydrazine is oxidised before the onset of oxidation of the other component. Mixtures of hydrazine and UDMH have been assayed in both aqueous and non-aqueous media and a comparison of results has been reported. The main advantage of the proposed methods is that they can be applied to industrial samples, which would render other methods impossible.
    Notizen: Zusammenfassung Binäre Mischungen von Hydrazin mit Ammoniak, Anilin, Hydroxylamin, Thiocyanat und asymmetrischem Dimethylhydrazin wurden thermometrisch analysiert. Sowohl die basischen als auch die reduzierenden Eigenschaften des Hydrazins bilden die Grundlage der Titrationen. Zum Beispiel wird im Gemisch Hydrazin/Ammoniak der Gesamtbasengehalt acidimetrisch ermittelt und die Hydrazinkomponente durch Oxydation mit Bromat bestimmt. Im Gemisch Anilin/Hydrazin oder Hydroxylamin/Hydrazin wird mit Bromat zunächst alles Hydrazin oxydiert, bevor die Oxydation der zweiten Komponente einsetzt. Mischungen von Hydrazin mit asym. Dimethylhydrazin werden in wäßrigem und auch in nichtwäßrigem Medium ausgeführt und die Ergebnisse verglichen. Der Hauptvorteil der beschriebenen Verfahren besteht darin, daß auch industrielle Proben untersucht werden können, bei denen andere Verfahren versagen würden.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00439074
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  • 98
    Digitale Medien
    Digitale Medien
    Titrimetric determinations of cryptands and cryptates (1979)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 358-362 
    Details
    ISSN: 1618-2650
    Schlagwort(e): Best von Kryptanden, Kryptaten ; Volumetrie ; HCl, Metall-Standardlösung, Standardzugabeverfahren
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Summary Using bromocresol green as a visual endpoint indicator solutions of the cryptands [2.2.1] and [2.2.2] can be determined by titration with HCl in the concentration range of 10−1–10−3 M with relative standard deviations of 0.2–0.4 %. If both cryptand and cryptate are present in one solution, then the sum of them can be determined titrimetrically in the same way. It is also possible to determine the contents of [2.2.1] and [2.2.2] by using a calcium or barium standard solution and the unknown cryptand solution as a titrant. By evaluation of the pH-curve thus obtained, the endpoint of the titration can be determined. In the concentration range of 10−1–10−2 M relative standard deviations of about 0.5% are obtained. [2.2.1] cryptand solutions are determined by using the standard addition technique of Gran with a calcium chloride solution. An ion-selective electrode is used as a probe for calcium ions. If this method is applied, the relative standard deviation in the range of 10−2–10−4 M solutions is approximately 3%. With this technique cryptand can be analysed even when cryptate is present in the solution.
    Notizen: Zusammenfassung Bei Verwendung von Bromkresolgrün als visueller Endpunktindicator kann man [2.2.1] und [2.2.2] Kryptandlösungen im Konzentrationsbereich 10−1–10−3 M mit relativen Standardabweichungen von 0,2–0,4% mit HCl titrieren. Wenn in einer Lösung sowohl Kryptand als auch Kryptat vorhanden ist, ist die Summe beider Substanzen auf die gleiche Weise bestimmbar. [2.2.1] und [2.2.2] können auch dadurch bestimmt werden, daß eine Calciumbzw. Barium-Standardlösung mit der Kryptandlösung unbekannter Konzentration titriert wird. Die Auswertung der dabei erhaltenen pH-Kurve ergibt den Titrationsendpunkt, wobei hierdurch im Konzentrationsbereich von 10−1–10−2 M Kryptandlösungen relative Standardabweichungen von etwa 0,5% erreicht werden. [2.2.1] Kryptandlösungen werden außerdem mit der Standard-Additionstechnik nach Gran bestimmt, wobei eine calciumselektive Elektrode als Indicatorelektrode dient. Dabei werden im Konzentrationsbereich von 10−2–10−4 M relative Standardabweichungen von etwa 3 % erhalten. Diese Methode kann auch überschüssigen Kryptand neben Kryptat bestimmen.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00482014
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  • 99
    Digitale Medien
    Digitale Medien
    Titrimetry in a continuous flow system (1978)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 293 (1978), S. 413-415 
    Details
    ISSN: 1618-2650
    Schlagwort(e): Best. von Sulfat in Umweltmaterial ; Volumetrie ; Durchflußsystem, Dimethylsulfonazo als Indicator
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00471465
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  • 100
    Digitale Medien
    Digitale Medien
    Identification and detection of carbamate pesticides in autopsy tissues using thin-layer chromatography (1979)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 287-287 
    Details
    ISSN: 1618-2650
    Schlagwort(e): Nachw. von Carbamatpesticiden in biolog. Material ; Chromatographie, Dünnschicht
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00481656
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