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  • United States  (291)
  • Phosphorylation  (128)
  • kinetics  (125)
  • American Association for the Advancement of Science (AAAS)  (409)
  • Springer  (135)
  • 1995-1999  (544)
  • 1999  (298)
  • 1998  (246)
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  • American Association for the Advancement of Science (AAAS)  (409)
  • Springer  (135)
  • Wiley-Blackwell  (35)
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  • 1995-1999  (544)
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  • 1
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of MnO2 dissolution in H2SO4 in the presence of pyrite (1999)
    Springer
    Journal of applied electrochemistry 29 (1999), S. 191-200 
    Details
    ISSN: 1572-8838
    Keywords: cyclic redox reaction ; dissolution ; kinetics ; manganese dioxide ; mechanism ; pyrite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract This paper describes a study of the kinetics and mechanism of MnO2 dissolution in H2SO4 in the presence of pyrite through leaching and electrochemical parameters. Manganese(iv) was found to dissolve mainly through reduction by the ferrous ion generated during oxidation of pyrite by the ferric ion. The oxidation which is slower and rate controlling may proceed through two different reactions, one producing S0 and the other SO42−. Manganese dissolution runs at the same rate as that of pyrite oxidation by maintaining ferrous ion concentration at a much lower level than that of ferric. Kinetic equations based on corrosion coupling principles are developed to explain the observed leaching behaviour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003490810114
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  • 2
    Electronic Resource
    Electronic Resource
    Molecular structure of trans-[Co(NH3)4(NH2CH3)Cl](ClO4)2 (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 69-72 
    Details
    ISSN: 1572-8854
    Keywords: Co(III) complex ; crystal structure ; kinetics ; steric effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in the orthorhombic space group Pnma, with a = 7.9209(5), b = 9.818(1), c = 16.867(2) Å, and Z = 4. The structure was solved employing 1864 independent x-ray reflections with I〉2σ(I) by Patterson and difference Fourier techniques and refined by full-matrix least-squares to R = 0.036. The trans-[CO(NH3)4(NH2CH3)Cl](ClO4)2 molecule is on a crystallographic mirror plane. The cobalt ion is in an elongated octahedral coordination with four equatorial ammonia ligands [average Co–N distance equal to 1.966(2) Å], an axial methylamine [Co–N=1.965(3)Å], and an axial chlorine ion [Co–Cl=2.2771(9)Å]. Kinetic steric effects of the complex are interpreted in terms of structural results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021786804676
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  • 3
    Electronic Resource
    Electronic Resource
    Factors affecting bioleaching kinetics of sulfide ores using acidophilic micro-organisms (1999)
    Springer
    BioMetals 12 (1999), S. 1-10 
    Details
    ISSN: 1572-8773
    Keywords: acidophilic ; strain ; oxidation ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Recovery of metal values from sulfide ores by use of acidophilic microorganisms is gaining importance. A number of commercial/pilot plants are setup to find out the techno-economic feasibility of the overall process. The main drawback in the process is the slow kinetics of dissolution of metal values from the sulfide ores. To make the technology e attractive the kinetics should be improved considerably. There are various factors which determine the overall kinetics such as bacterial activity and concentration, iron and sulfur oxidation, oxygen consumption, reactor design and nature of ore. A brief review has been made dealing with the above parameters
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009228210654
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  • 4
    Electronic Resource
    Electronic Resource
    Reaction Between Copper Nitrate Hydrate and Methoxydimethyloctylsilane in Methanol (1998)
    Springer
    Journal of solution chemistry 27 (1998), S. 1123-1138 
    Details
    ISSN: 1572-8927
    Keywords: Sol–gel processing ; hydrolysis ; condensation ; kinetics ; methoxydimethyloctylsilane ; copper nitrate hydrate ; phase diagram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The reaction rate was determined for copper nitrate hydrate with methoxydimethyloctylsilane (MDOS) in methanol. The rate constants of hydrolysis and condensation were established by quantitative measurement of the product and Karl Fischer water determination. The reaction with the hydrated copper salt resulted in the phase separation of an insoluble product from the reaction mixture. The structure of the product was determined, by Fourier Transform Infrared Spectrometry (FTIR) and Nuclear Magnetic Resonance (NMR) to be a dimer of the MDOS. The results showed the alcohol, producing condensation reaction was negligible in the formation of the dimer. contrary to the case for the well-known reaction by trialkoxysilanes and tetraalkoxysilanes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022662017881
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  • 5
    Electronic Resource
    Electronic Resource
    Reaction Kinetics for the Anionic Ring-Opening Polymerization of Tetraphenyltetramethylcyclotetrasiloxane Using a Fast Initiator System (1998)
    Springer
    Journal of inorganic and organometallic polymers and materials 8 (1998), S. 111-117 
    Details
    ISSN: 1572-8870
    Keywords: Organosiloxane ; kinetics ; poly(phenylmethylsiloxane) ; catalyst ; anionic ; ring-opening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract It is well known that the rate of polymerization for an anionic mechanism is dependent on the ability of the bulk material or solvent system to disassociate the ion pair at the propagating chain end. In the anionic ring-opening polymerization of cyclic organosiloxanes in particular, the larger and softer the counter ion, the more rapidly the reaction proceeds. A recently developed phosphazene initiator system provides a large, soft counter ion relative to other traditional initiators used for the polymerization of poly(dimethylsiloxane) (PDMS). This novel initiator system was used in this investigation for the ring-opening polymerization of tetraphenyltetramethylcyclotetrasiloxane (P4) and the reaction kinetics under bulk and solution conditions were investigated. The new initiator system showed a dramatic increase in the rate of polymerization over the conventional potassium hydroxide-catalyzed system. Furthermore, this initiator was sufficiently reactive to be useful for the ring-opening polymerization of P4 at 293 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022487906770
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  • 6
    Electronic Resource
    Electronic Resource
    Degradation of Cellulosic Materials Under the Alkaline Conditions of a Cementitious Repository for Low- and Intermediate-Level Radioactive Waste. II. Degradation Kinetics (1999)
    Springer
    Journal of polymers and the environment 7 (1999), S. 41-51 
    Details
    ISSN: 1572-8900
    Keywords: Cellulose ; alkaline degradation ; peeling off ; degree of polymerization ; kinetics ; (gluco)isosaccharinic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The degradation of cellulosic materials, differing mainly in the degree of polymerization and the number of reducing end groups, was studied under the alkaline conditions similar to those existing in a cementitious repository for low- and intermediate-level radioactive waste (pH 13.3, T = 25°C). The kinetics of alkaline degradation (peeling-off reaction) were studied and the data analyzed by the model of Haas et al. [13]. The observed kinetic parameters for the propagation reaction and overall stopping reaction were compared with literature data. Although measured under different experimental conditions, literature data and data from this study show a consistent picture. Differences in the extent of degradation observed for the different cellulosic materials could be satisfactorily explained by differences in reducing end group content and, consequently, by differences in the degrees of polymerization. Besides the number of reducing end groups, the degree of amorphousness also plays an important role. The main degradation products formed under the experimental conditions used are α- and β-(gluco)isosaccharinic acid. This is in agreement with many other studies on alkaline degradation of cellulose. The two isomers are formed in roughly equal amounts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021894102937
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  • 7
    Electronic Resource
    Electronic Resource
    High resolution NMR techniques in catalysis (1998)
    Springer
    Topics in catalysis 5 (1998), S. 133-147 
    Details
    ISSN: 1572-9028
    Keywords: NMR ; catalysis ; high pressure ; dynamic equilibria ; magnetization transfer ; sapphire tube ; gas phase ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract High resolution NMR techniques are applicable to a variety of aspects of catalysis. Methods for studying homogeneously-catalyzed systems under high gas pressure are described along with approaches for obtaining mechanistic and dynamic information. Many of the same techniques may be applied to heterogeneous catalysis by following the reaction chemistry by gas phase NMR.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019133515789
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  • 8
    Electronic Resource
    Electronic Resource
    Selectivity from a kinetic point of view: nonlinear behavior of logarithmic product ratios as a function of the reciprocal temperature (1998)
    Springer
    Topics in catalysis 5 (1998), S. 159-176 
    Details
    ISSN: 1572-9028
    Keywords: nonlinear temperature behavior ; Eyring plot ; modified Eyring plot ; selectivity ; selection process ; enantioselectivity ; selection level ; isoinversion principle ; isoinversion temperature ; inversion temperature ; kinetics ; catalysis ; asymmetric hydrogenation ; dihydroxylation ; cocyclization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The influence of the temperature on selectivity is described under special consideration of nonlinearities in the corresponding modified Eyring plots. Reasons for the experimentally well-known behavior are discussed. Furthermore, the conditions for nonlinear temperature behavior are quantified and a concept is described which allows the determination of the temperature dependence of a single reaction pathway in a selection process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019185532627
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  • 9
    Electronic Resource
    Electronic Resource
    Sorption Equilibria and Kinetics of Hydrocarbons onto Activated Carbon Samples Having Different Micropore Size Distributions (1999)
    Springer
    Adsorption 5 (1999), S. 25-37 
    Details
    ISSN: 1572-8757
    Keywords: micropore size distribution ; activated carbon ; adsorption ; desorption ; equilibrium ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract This paper deals with the prediction of adsorption equilibrium and kinetics of hydrocarbons onto activated carbon samples having different micropore size distribution (MPSD). The microporous structure of activated carbon is characterised by the distribution of slit-shaped micropores, which is assumed to be the sole source of surface heterogeneity. The interaction between adsorbate molecule and pore walls is described by the Lennard-Jones potential theory. Different adsorbates have access to different pore size range of activated carbon due to the size exclusion, a phenomenon could have a significant influence on both multicomponent equilibria and kinetics. Activated carbons with three different MPSDs are studied with ethane and propane as the two model adsorbates. The Heterogeneous Macropore Surface Diffusion model (HMSD) is employed to simulate adsorption kinetics. The simulation results show that the MPSD is an important factor affecting both the multicomponent equilibria and kinetics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026481704926
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  • 10
    Electronic Resource
    Electronic Resource
    Furfural hydrogenation over carbon‐supported copper (1999)
    Springer
    Catalysis letters 60 (1999), S. 51-57 
    Details
    ISSN: 1572-879X
    Keywords: furfural hydrogenation ; Cu/carbon catalysts ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Furfural hydrogenation over copper dispersed on three forms of carbon – activated carbon, diamond and graphitized fibers – were studied. Only hydrogenation of the C=O bond to form either furfuryl alcohol or 2‐methyl furan occurred at temperatures from 473 to 573 K. Reduction at 573 K gave the most active catalysts, all three catalysts had activation energies of 16 kcal/mol, and turnover frequencies were 0.018–0.032 s-1 based on the number of Cu0 + Cu+ sites, which were counted by N2O adsorption at 363 K and CO adsorption at 300 K, respectively. The Cu/activated carbon catalyst showed no deactivation during 10 h on stream, in contrast to the other two catalysts. A simple Langmuir–Hinshelwood model invoking two types of sites was able to fit all kinetic data quite satisfactorily, thus it was consistent with the presence of both Cu0 and Cu+ sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019090520407
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  • 11
    Electronic Resource
    Electronic Resource
    Study of the ammonia decomposition over iron catalysts (1999)
    Springer
    Catalysis letters 60 (1999), S. 167-171 
    Details
    ISSN: 1572-879X
    Keywords: ammonia decomposition ; iron catalyst ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The decomposition of ammonia is a reaction associated with the process of the nitriding of metals. The kinetics of the ammonia decomposition on iron catalysts has been studied using a differential reactor with internal mixing. The balance between the inlet and outlet ammonia quantity has been used to determine the degree of conversion. The rate of ammonia decomposition could be described by the following expression: r = k0 exp (Ea/RT)pNH3. The activation energy of the ammonia decomposition process has been found for samples with potassium as E a= 96 kJ/mol, for samples without potassium as E a= 87 kJ/mol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019007024041
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  • 12
    Electronic Resource
    Electronic Resource
    Pure and Binary Gas Adsorption Equilibria and Kinetics of Methane and Nitrogen on 4A Zeolite by Isotope Exchange Technique (1999)
    Springer
    Adsorption 5 (1999), S. 145-158 
    Details
    ISSN: 1572-8757
    Keywords: kinetics ; isotope-exchange ; nitrogen ; adsorption ; methane ; zeolite ; equilibria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The Isotope Exchange Technique (IET) was used to simultaneously measure pure and binary gas adsorption equilibria and kinetics (self-diffusivities) of CH4 and N2 on pelletized 4A zeolite. The experiment was carried out isothermally without disturbing the adsorbed phase. CH4 was selectively adsorbed over N2 by the zeolite because of its higher polarizability. The multi-site Langmuir model described the pure gas and binary adsorption equilibria fairly well at three different temperatures. The selectivity of adsorption of CH4 over N2 increased with increasing pressure at constant gas phase composition and temperature. This curious behavior was caused by the differences in the sizes of the adsorbates. The diffusion of CH4 and N2 into the zeolite was an activated process and the Fickian diffusion model described the uptake of both pure gases and their mixtures. The self-diffusivity of N2 was an order of magnitude larger than that for CH4. The pure gas self-diffusivities for both components were constants over a large range of surface coverages (0 〈 θ 〈 0.5). The self-diffusivities of CH4 and N2 from their binary mixtures were not affected by the presence of each other, compared to their pure gas self-diffusivities at identical surface coverages.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008917308002
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  • 13
    Electronic Resource
    Electronic Resource
    Solvent effects in the kinetics of the enantioselective hydrogenation of ethyl pyruvate (1998)
    Springer
    Catalysis letters 55 (1998), S. 73-77 
    Details
    ISSN: 1572-879X
    Keywords: enantioselectivity ; hydrogenation of ethyl pyruvate ; Pt/alumina catalyst ; solvent effects ; kinetics ; solvent polarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The influence of solvent on the kinetics of enantioselective hydrogenation of ethyl pyruvate by Pt/Al2O3/dihydrocinchonidine is reported. In a non‐polar solvent, toluene, the reaction is approximately zero order in substrate at constant hydrogen pressure, while under the same conditions and at the same substrate concentration, in the polar solvents ethanol and propylene carbonate the reaction shows a first‐order substrate concentration dependence. Fits to a Michaelis–Menten rate expression show that these differences are the expression of the relative magnitudes of the adsorption term in the rate expression, which in turn reflects the influence of the solvent on the adsorption–desorption processes which take place at the catalyst surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019078727850
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  • 14
    Electronic Resource
    Electronic Resource
    The detailed kinetics of the desorption of hydrogen from polycrystalline copper catalysts (1999)
    Springer
    Catalysis letters 59 (1999), S. 143-149 
    Details
    ISSN: 1572-879X
    Keywords: hydrogen ; desorption ; copper ; activation energy ; kinetics ; order of desorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of desorption of hydrogen from the copper component of an alumina-supported polycrystalline copper catalyst has been studied in detail by temperature-programmed desorption (TPD). Line-shape analysis of the hydrogen TPD spectra shows: (i) that the desorption is second order, (ii) that the desorption activation energy is in the range 64–68 kJ mol−1 in the coverage range 7–44% of a monolayer, and (iii) that the desorption pre-exponential term has a value ∼10−5 cm2 s−1 atom−1 consistent with the desorption being second order, involving mobile adsorbates and a mobile desorption transition state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019080823616
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  • 15
    Electronic Resource
    Electronic Resource
    Transformation kinetics and potential availability of specifically-sorbed phosphate in soils (1998)
    Springer
    Nutrient cycling in agroecosystems 51 (1998), S. 209-215 
    Details
    ISSN: 1573-0867
    Keywords: Desorption ; kinetics ; microbial transformation ; phosphate ; soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The improvement of P management in agriculture and environment requires a good understanding of residual effect of applied P in soils. The specific adsorption of P on variable charge minerals has been considered as the major mechanism that leads to a very low utilization of P fertilizer by crops within a growing season in Chinese red soils. Soil incubation and isotope tracing analysis were carried out to examine the transformation kinetics and potential availability of added specifically sorbed 32P in two pH contrasting light textured soils. The 32P recovered by 0.5 M NaHCO3 extraction and microbial biomass-P measurement from the added specifically sorbed 32P in the soils was well described by a first-order reaction and a Langmuir-type kinetic model, with correlation coefficients (R) being, on average, 0.938 and 0.959, respectively. The half-life (t1/2, from the first-order model) of the four tested mineral-P complexes ranged from 29 to 47 d in the acid sandy soil and 33 to 105 d in the neutral silty soil. Goethite-P was the most stable among the four tested mineral-P complexes. The potential availability of the mineral complex P (q m , in percent of total 32P added) obtained from the Langmuir equation ranged from 43.7 to 90.9% for the four mineral-P complexes, and decreased in the order: Al oxide-P (90.9%) 〉 montmorillonite-P (86.2%) 〉 kaolinite-P (77.5%) 〉 goethite-P (60.2%) in the acid sandy soil, whereas the order was Al oxide-P (89.3%) 〉 kaolinite-P (86.2%) 〉 montmorillonite-P (82.6%) 〉 goethite-P (43.7%) in the neutral silty soil. Based on the release rate and potential availability, kaolinite-P and Al oxide-P could be important sources for residual effect of applied P in variable-charge soils. The goethite-P has the lowest release rate and potential availability among the mineral-P complexes, implying that iron oxides may be the most important variable-charge mineral responsible for P fixation in the Chinese red soils.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009749619865
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  • 16
    Electronic Resource
    Electronic Resource
    Growth of Ordered Domains in a Computer Model Alloy with Lattice Misfit (1999)
    Springer
    Journal of statistical physics 95 (1999), S. 23-43 
    Details
    ISSN: 1572-9613
    Keywords: model alloy ; Monte Carlo ; elastic interactions ; phase separation ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We study via Monte Carlo simulations the influence of elastic interactions on the ordering and decomposition of a two-dimensional model binary alloy with antiferromagnetic nearest and ferromagnetic next nearest neighbor type interactions following a quench into the coexistence region. The elastic interaction leads to the development of a platelet morphology for the segregated ordered and disordered regions. A length scale characterizing the coarsening process follows a law of the type R=a+bt 1/3 with the growth b decreasing with the amount of ordered phase; this appears to be due to the presence of anti-phase boundaries between neighboring domains ordered on different sublattices which are difficult to eliminate. The application of uniaxial external stress results in “rafting” of the domains. Many of the simulation results are in agreement with experimentally observed effects in nickel-base superalloys.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004569209618
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  • 17
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    Seeing Patterns: Models, Visual Evidence and Pictorial Communication in the Work of Barbara McClintock (1999)
    Springer
    Journal of the history of biology 32 (1999), S. 163-195 
    Details
    ISSN: 1573-0387
    Keywords: cytogenetics ; diagrams ; genetics ; illustrations ; McClintock ; models ; molecular biology ; photographs ; twentieth-century ; United States
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , History
    Notes: Abstract Barbara McClintock won the Nobel Prize in 1983 for her discovery of mobile genetic elements. Her Nobel work began in 1944, and by 1950 McClintock began presenting her work on “controlling elements.” McClintock performed her studies through the use of controlled breeding experiments with known mutant stocks, and read the action of controlling elements (transposons) in visible patterns of pigment and starch distribution. She taught close colleagues to “read” the patterns in her maize kernels, “seeing” pigment and starch genes turning on and off. McClintock illustrated her talks and papers on controlling elements or transposons with photographs of the spotted and streaked maize kernels which were both her evidence and the key to her explanations. Transposon action could be read in the patterns by the initiated, but those without step by step instruction by McClintock or experience in maize often found her presentations confusing. The photographs she displayed became both McClintock's means of communication, and a barrier to successful presentation of her results. The photographs also had a second and more subtle effect. As images of patterns arrived at through growth and development of the kernel, they highlight what McClintock believed to be the developmental consequences of transposition, which in McClintock's view was her central contribution, over the mechanism of transposition, for which she was eventually recognized by others. Scientific activities are extremely visual, both at the sites of investigation and in communication through drawings, photographs, and movies. Those visual messages deserve greater scrutiny by historians of science.
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    URL: http://dx.doi.org/10.1023/A:1004420726771
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  • 18
    Electronic Resource
    Electronic Resource
    Tissue-specific requirements for a phosphorylation site in the Fushi tarazu homeodomain (1999)
    Springer
    Development genes and evolution 209 (1999), S. 427-431 
    Details
    ISSN: 1432-041X
    Keywords: Key words Drosophila ; Fushi tarazu ; Homeodomain ; Phosphorylation ; Neurogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The homeodomain protein Fushi tarazu (Ftz) is required for several embryonic patterning processes including segmentation and neurogenesis. During the stages that these processes are regulated the protein is differentially phosphorylated, suggesting that phosphorylation plays a role in helping the protein to regulate different functions in different tissues. We showed in a recent study that one of the Ftz phosphorylation sites, a protein kinase A-type site in the N-terminal arm of the homeodomain, is required for normal Ftz-dependent segmentation. Here we test whether phosphorylation of this site (Thr-263) is also required in the developing central nervous system (CNS). A well-established role for Ftz in the CNS is for the differentiation of neurons referred to as RP2 neurons. Absence of Ftz expression in these cells causes a failure of certain target genes to be expressed and subsequent defects in RP2 differentiation. In contrast to its effect on segmentation, we find that mutation of Thr-263 to Ala (or Asp) has no effect on these CNS functions. This suggests that the phosphorylation state of this site is irrelevant for Ftz function in the CNS, and that there are tissue-specific differences in the requirements for Ftz phosphorylation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004270050273
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  • 19
    Electronic Resource
    Electronic Resource
    Analysis of potential phosphorylation sites in human T cell leukemia virus type 1 Tax (1999)
    Springer
    Journal of biomedical science 6 (1999), S. 206-212 
    Details
    ISSN: 1423-0127
    Keywords: Tax ; HTLV-1 ; Trans-activation ; Phosphorylation ; Mutagenesis ; Transcription ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The human T cell leukemia virus type 1 (HTLV-1) Tax is a phosphoprotein, however, the contribution of phosphorylation to Tax activity is unknown. Previous studies have shown that phosphorylation of Tax occurs on serine residue(s), within one tryptic fragment, in response to 4β-phorbol-12β-myristate-13α-acetate, in both mouse and human cells. Studies were conducted in multiple cell lines to identify the specific phosphorylated serines as a prelude to functional analysis. The phosphorylation pattern of Tax was found to be different in 293T and COS-7 cells in comparison with MT-4 and Px-1 cells. However, one tryptic fragment remained consistent in comigration analyses among all cell lines. Using selected Tax serine mutants a tryptic fragment containing a serine at residue 113 believed to be the site of phosphorylation of Tax did not comigrate with the common phosphorylated tryptic fragment. Analysis of selected Tax mutants for ability totrans-activate the cytomegalovirus promoter demonstrated mutation of serine 77 to alanine reducedtrans-activation by 90% compared to wild-type Tax. However, examination of the phosphorylation pattern of the serine 77 mutant demonstrated that it is not the site of phosphorylation. These studies demonstrate the importance of using relevant cell lines to characterize the role of phosphorylation in protein function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02255904
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  • 20
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    An acidic modification of the cytoplasmic domain contributes to the charge heterogeneity of the MHC class I antigens (1998)
    Springer
    Immunogenetics 47 (1998), S. 381-389 
    Details
    ISSN: 1432-1211
    Keywords: Key words H2 ; Histocompatibility ; 2-D PAGE ; Glycan ; Phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Polypeptide phosphorylation and sialylation of the glycan moieties contribute to the charge heterogeneity of the class I major histocompatibility complex glycoproteins. The present study demonstrates that a unique acidic modification unrelated to phosphorylation or glycosylation also affects the charge heterogeneity of the H2-Kk heavy chain of BW5147 lymphoma cells. In vitro cultivation of BW5147 cells results in changes in charge heterogeneity of the H2-Kk heavy chains due to the unique acidic modification. Sequential papain digestion of the 45 000 M r H2-Kk glycoprotein yields a 42 500 M r glycopolypeptide initially, followed by production of a 39 000 M r glycopolypeptide. Results from experiments designed to localize and characterize the novel acidic modification suggest that the modification resides in the segment of the H2-Kk polypeptide located between the two papain cleavage sites. This portion of the polypeptide consists of the transmembrane region and part of the cytoplasmic domain of the H2-Kk heavy chain. At steady state, 25% of the total cell surface H2-Kk possesses this modification. In addition, the modification is mutually exclusive with the phosphorylation of the H2-Kk heavy chain at Ser-333. The possible biological significance of the novel modification of class I antigens is discussed.
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    URL: http://dx.doi.org/10.1007/s002510050373
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    The β7 integrin gene (Itgb-7) promoter is responsive to TGF-β1: defining control regions (1998)
    Springer
    Immunogenetics 48 (1998), S. 184-195 
    Details
    ISSN: 1432-1211
    Keywords: Key words β7 integrin gene ; Promoter elements ; TGFβ1 ; Phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The β7 integrins LPAM-1 (α4β7) and M290 (αEβ7) mediate the homing of lymphocytes to gut-associated lymphoid tissue, and the proposed retention of intraepithelial lymphocytes (IEL), respectively. Here we show that the gut mucosal cytokine TGF- β1 increases the expression of β7 and αE subunit mRNA transcripts and the cell-surface expression of M290 on T cells, and that it decreases the level of α4 integrin transcripts. Induced β7 integrin gene expression was inhibited by the protein tyrosine kinase inhibitor genistein, implicating a role for tyrosine phosphorylation. An analysis of the β7 integrin gene promoter revealed three DNAse I hypersensitivity sites, two of which mapped to the 5′ and 3′ ends of a promoter fragment (nucleotides +690 to +63) that directed both the basal and the TGF-β1-induced expression of a heterologous reporter gene. Deletion analysis identified two TGF-β1 response regions encompassing nucleotides –509 to –398 (TGFBRR1), and –122 to +32 (TGFBRR2). TGFBRR1 interacted with at least five protein complexes, whose binding could be induced with TGF-β1 stimulation and could be antagonized by TGFBRR2 which harbored both similar and distinctive cis-elements. TGFBRR2 interacted specifically with at least two major nuclear protein complexes, whose binding was phosphorylation dependent. These data provide new insights into the mechanism by which TGF-β may switch LPAM-1+ve migrating T cells to express M290, facilitating their retention in the gut.
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    URL: http://dx.doi.org/10.1007/s002510050422
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    Purification of a nitrate reductase kinase from Spinacea oleracea leaves, and its identification as a calmodulin-domain protein kinase (1998)
    Springer
    Planta 206 (1998), S. 435-442 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Calmodulin-domain protein kinase ; Nitrate reductase ; Phosphorylation ; 14-3-3 proteins ; Spinacea (nitrate reductase)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Spinach (Spinacea oleracea L.) nitrate reductase (NR) is inactivated by phosphorylation on serine-543, followed by binding of the phosphorylated enzyme to 14-3-3 proteins. We purified one of several chromatographically distinct NRserine-543 kinases from spinach leaf extracts, and established by Edman sequencing of 80 amino acid residues that it is a calcium-dependent (calmodulin-domain) protein kinase (CDPK), with peptide sequences very similar to Arabidopsis CDPK6 (accession no. U20623; also known as CPK3). The spinach CDPK was recognized by antibodies raised against Arabidopsis CDPK. Nitrate reductase was phosphorylated at serine-543 by bacterially expressed His-tagged CDPK6, and the phosphorylated NR was inhibited by 14-3-3 proteins. However, the bacterially expressed CDPK6 had a specific activity approx. 200-fold lower than that of the purified spinach enzyme. The physiological control of NR by CDPK is discussed, and the regulatory properties of the purified CDPK are considered with reference to current models for reversible intramolecular binding of the calmodulin-like domain to the autoinhibitory junction of CDPKs.
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    URL: http://dx.doi.org/10.1007/s004250050419
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    Thermoxidative Decomposition of Some Polysulfones under Dynamic Conditions of Heating (1998)
    Springer
    Journal of thermal analysis and calorimetry 52 (1998), S. 569-579 
    Details
    ISSN: 1572-8943
    Keywords: bromomethylated polysulfone ; carboxylated polysulfone ; kinetics ; polysulfone ; thermoxidative decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Kinetic aspects of the first step of thermoxidative decomposition, under dynamic conditions of heating, of some polysulfones have been studied. The dependence of the kinetic parameters on the heating rate and conversion degree has been established. The compensation effect and conversion function have also been discussed. Polysulfone decomposes by the breaking of the main chain, a process involving very high activation energy. Chemically modified polysulfones show the first step of thermoxidative decomposition at relatively low temperatures. This step corresponds to the elimination of functional side - groups for the bromomethylated polysulfone while in the case of the carboxylated polysolfone, the loss of the carboxyl group is probably accompanied by a crosslinking reaction.
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    Thermal Decomposition of BaC2O4·0.5H2O Studied by Stepwise Isothermal Analysis and Non-Isothermal Thermogravimetry (1998)
    Springer
    Journal of thermal analysis and calorimetry 53 (1998), S. 397-410 
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    ISSN: 1572-8943
    Keywords: barium oxalate ; kinetics ; non-isothermal thermogravimetry ; stepwise isothermal analysis ; thermal decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermal decomposition of BaC2O4·0.5H2O in air was studied by a combination of stepwise isothermal analysis (SIA) and non-isothermal thermogravimetry. The results from both techniques show that the crystal water is released in one step and that anhydrous barium oxalate is decomposed in one step, while BaCO3 decomposes in three steps to BaO, forming two intermediate compounds with the formulas of BaCO3·(BaO)2 and (BaCO3)0.5·(BaO)2.5. Reaction mechanism analyses using the data from SIA measurements show that the controlling mechanism for all the five decomposition steps in isothermal conditions is a two-dimensional phase-boundary controlled process. Kinetic parameters are obtained for the five decomposition steps from the non-isothermal thermogravimetric data.
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    Obtaining Kinetic Parameters by Modulated Thermogravimetry (1998)
    Springer
    Journal of thermal analysis and calorimetry 54 (1998), S. 695-704 
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    ISSN: 1572-8943
    Keywords: activation energy ; decomposition ; kinetics ; modulated temperature ; thermogravimetry ; volatilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new technique, called modulated thermogravimetry, is introduced as a tool for obtaining continuous kinetic information for decomposition and volatilization reactions. The approach makes use of an oscillatory temperature program to obtain kinetic parameters during a mass loss. MTGA™ may be used under quasi-isothermal conditions to observe a single mass loss or may be combined with linear heating rate or Hi-Res™ controlled rate thermogravimetry to scan from one mass loss region to another. Results obtained are in agreement with those obtained by other kinetic methods.
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    URL: http://dx.doi.org/10.1023/A:1010171315715
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    Kinetic Studies on the Thermal Dissociation of β-Cyclodextrin·Ethyl Benzoate Inclusion Complexes (1998)
    Springer
    Journal of thermal analysis and calorimetry 54 (1998), S. 947-956 
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    ISSN: 1572-8943
    Keywords: β-cyclodextrin ; ethyl benzoate ; inclusion complex ; kinetics ; thermal decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The stability of β-cyclodextrin·ethyl benzoate·6H2O(β-CD·C6H5COOC2H5·6H2O) was investigated by TG and DSC. The mass loss takes place in three stages: the dehydration occurs at 50-120°C; the dissociation of β-CD·C6H5COOC2H5occurs at 200-260°C; the decomposition of β-CD begins at 280°C. The kinetics of the dissociation of β-CD·C6H5COOC2H5in a dry nitrogen flow was studied by means of thermogravimetry both at constant temperature and linearly increasing temperature. The results show that the dissociation of β-CD·C6H5COOC2H5is dominated by a three-dimensional diffusion process (D3). The activation energy E is 116.19 kJ mol-1and the pre-exponential factor A 6.5358·109min-1. Cyclodextrin is able to form inclusion complexes with a great variety of guest molecules, and the studies focus on the energy of binding between cyclodextrin and the guest molecule. In this paper, the β-cyclodextrin·ethyl benzoate inclusion complex was studied by fluorescence spectrophotometry and infrared absorption spectroscopy, and the results show that the stable energy of inclusion complexes of β-CD with weakly polar guest molecules consists mainly of van der Waals interaction.
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    Thermal Analysis Studies on Isopropylnitrate (1999)
    Springer
    Journal of thermal analysis and calorimetry 55 (1999), S. 9-19 
    Details
    ISSN: 1572-8943
    Keywords: ARC ; DSC ; HFC ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Isopropylnitrate (IPN) is described as a detonable material used in propellants and explosives. While there is considerable information available on its sensitivity and compatibility with other materials, very little is known about its thermochemical properties. This paper will describe the results obtained from some DSC, heat flux calorimetry (HFC) and accelerating rate calorimetry (ARC) measurements. The ASTM DSC method using a hermetic aluminum pan having a lid with a laser-produced pin hole was used to determine the vapour pressure of IPN1. Results calculated from an Antoine equation are in substantial agreement with those determined from DSC measurements. From the latter measurements, the enthalpy of vaporization was determined to be 35.32±0.62 kJ mol−1. Attempts to determine vapour pressures above about 0.8 MPa resulted in significant decomposition of IPNg. The enthalpy change for decomposition in sealed glass systems was found to be -3.43±0.09 kJ g−1 and -3.85±0.03 kJ g−1, respectively from DSC and HFC measurements on IPN1 samples loaded in air. Slightly larger exotherms were observed for the HFC results in air than those in inert gas, suggesting some oxidation occurs. In contrast, no significant difference in the observed onset temperature of about 150°C was observed for both the HFC and ARC results. From DSC measurements, an Arrhenius activation energy for decomposition of 126±4 kJ mol−1 was found. These measurements were also conducted in sealed glass systems and decomposition appeared to proceed primarily from the liquid phase.
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    Kinetics of Thermal Decomposition of Mixed Ligand Trinuclear Compound of Cadmium(II) (1999)
    Springer
    Journal of thermal analysis and calorimetry 55 (1999), S. 233-241 
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    ISSN: 1572-8943
    Keywords: cadmium(II) atom ; kinetics ; non-isothermal decomposition ; Schiff-base compound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal C81H78N12O6Cd3 was synthesized and its structure was determined by single crystal X-ray diffraction method. The complex crystallizes in the monoclinic system space group P21/n with cell parameters, a=15.959(4) Å, b=26.222(3) Å, c=25.907(6) Å, β=101.60(2)°. The non-isothermal kinetics of the crystal was studied by use of non-isothermal TG and DTG curves. The kinetic parameters were analyzed by means of integral and differential methods, and mechanism functions of the thermal decomposition reaction for its second step were proposed. The kinetic equation of thermal decomposition is expressed as: dα/dt=Aexp(-E/RT)1.5(1-α)4/3[1/(1-α)1/3-1]−1. The average values of E(kJ mol−1) and lnA/s−1 are 339.25, 43.95, respectively.
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    Re-examination of the Kinetics of the Thermal Dehydroxylation of Goethite (1999)
    Springer
    Journal of thermal analysis and calorimetry 55 (1999), S. 301-309 
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    ISSN: 1572-8943
    Keywords: dehydroxylation ; goethite ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of thermal dehydroxylation of aluminuous goethites [1] synthesised from a ferrous salt has been re-examined using the general reaction order kinetic law. The utilised data processing was based on the procedures employed by dissolution kinetics. Recalculation of the activation energies EA of the dehydroxylation yielded the values 130, 132, 128, and 123 kJ mol−1 for pure goethite, goethite with 10, 20, and 30 mol% Al substitution, respectively. The values of EA are in a good agreement with those given for goethite in literature. The EA values are linearly related with the chemically bound excess H2O/OH− in the crystal lattice that is apparently influenced by Al substitution.
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    Thermogravimetric Analysis of Cobalt(II)-dothiepin Complexes (1999)
    Springer
    Journal of thermal analysis and calorimetry 55 (1999), S. 841-849 
    Details
    ISSN: 1572-8943
    Keywords: cobalt(II)-dothiepin ; kinetics ; TG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The complexes of cobalt(II) with dothiepin (DOT) hydrochloride have been studied for kinetics of thermal degradation by thermogravimetric analysis (TG) and derivative thermogravimetric studies (DTG) in a static nitrogen atmosphere at a heating rate of 10° C min−1. A general mechanism of thermal decomposition is advanced involving dehydration and decomposition process for both organic and inorganic ligands. The thermal degradation reactions were found to proceed in three steps having an activation energy in the range 6.75–170 kJ mol−1. Thermal decomposition kinetics parameters were computed on the basis of thermal decomposition data.
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    Gegeneration of Deactivated β-Zeolite by Coke Oxidation (1999)
    Springer
    Journal of thermal analysis and calorimetry 56 (1999), S. 297-303 
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    ISSN: 1572-8943
    Keywords: β-zeolite ; coke ; cumene ; kinetics ; regeneration ; TG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An accurate description of coke burn off is obtained from a catalyst based on β-zeolite and used for benzene alkylation with propylene giving cumene by using the thermogravimetric technique. A simple empirical kinetic model was successfully applied to interpolate the data of thermogravimetric analysis performed on samples after partial burn off. Different temperatures, partial pressures of oxygen and gas flow rates were the variables studied in order to calculate the apparent rates and the activation energy for the coke oxidation reaction and to outline the best conditions for the industrial regeneration procedure of our proprietary catalyst PBE-1 for cumene synthesis. Combining the unusually long lifetime per reaction cycle with the optimized regeneration procedure leads to an outstanding overall catalyst life.
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    Non-Isothermal Pyrolysis and Kinetics of Oil Shales (1999)
    Springer
    Journal of thermal analysis and calorimetry 56 (1999), S. 953-958 
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    ISSN: 1572-8943
    Keywords: differential scanning calorimeter ; kinetics ; oil shale ; pyrolysis ; thermogravimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In this research, non-isothermal pyrolysis behavior and kinetics of three oil shales were studied by thermal analysis methods. All the thermal effects were endothermic and no exothermic region was observed in DSC curves. When oil shales are heated in nitrogen atmosphere in TG/DTG, two different mechanisms causing loss of mass were observed. The region between ambient temperature and 500 K was distillation. The second mechanism was visbreaking and cracking and it was observed between the region 500 and 800 K. Kinetic parameters of all the samples are determined by Coats and Redfern method and the results are discussed with regard to their accuracy and the ease of interpretation.
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    Pre-Eutectic Densification of Calcium Carbonate Doped with Lithium Carbonate (1999)
    Springer
    Journal of thermal analysis and calorimetry 56 (1999), S. 1461-1473 
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    ISSN: 1572-8943
    Keywords: CaCO3 ; densification ; kinetics ; Li2CO3
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Pressureless sintering of CaCO3 was carried out, with Li2CO3 (from 0.5 to 8 wt%) as an additive, under different pressures of CO2. Densification occurs between 600 and 700°C. Sintering above the eutectic temperature (T〉662°C) leads to the decomposition of calcium carbonate and the materials become expanded. At 620° under 1 kPa of CO2, a relative density of 96% is reached. Li2CO3 enhances the densification process and grain growth of calcium carbonate. CO2 pressure slows down densification and grain growth kinetics. These results are explained by the influence of carbonate and calcium ion vacancies on the sintering mechanisms.
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    Thermal Behaviour and Decomposition Kinetics for Two Palladium(II) Complexes with 1-aminopyrene and its Derivative (1999)
    Springer
    Journal of thermal analysis and calorimetry 58 (1999), S. 383-391 
    Details
    ISSN: 1572-8943
    Keywords: 1-aminopyrene (apyr) ; N-(2-pyridylmethylene)-1-pyrenylamine (pmpa) ; kinetics ; palladium(II)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal decomposition studies for two palladium(II) complexes Pd(apyr)2Cl2 and Pd(pmpa)Cl2 (apyr=1−aminopyrene and pmpa=N−(2−pyridylmethylene)−1−pyrenylamine) were carried out in pure nitrogen using TG-DTG techniques. The non-isothermal kinetic parameters for the two complexes were evaluated employing the method suggested by Málek, Šesták, Koga et al. Based on the above results, thermal behaviour of the complexes were carefully discussed, which showed that not only the parameters value, but also the decomposition pattern and mechanism for complex 1 are different from complex 2.
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    Studies on the Kinetics of the First Order Autocatalytic Decomposition Reaction of Highly Nitrated Nitrocellulose (1999)
    Springer
    Journal of thermal analysis and calorimetry 58 (1999), S. 403-411 
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    ISSN: 1572-8943
    Keywords: first order autocatalytic reaction ; HNNC ; kinetics ; TG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of the first order autocatalytic decomposition reaction of highly nitrated nitrocellulose (HNNC, 14.14%N) was studied by using thermogravimetry (TG). The results show that the TG curve for the initial 50% of mass-loss of HNNC can be described by the first order autocatalytic equation $$\frac{{{\text{d}}y}} {{dt}} = - 10^{16.4} \exp \left( { - \frac{{210380}} {{RT}}} \right)y - 10^{16.7} \exp \left( { - \frac{{171205}} {{RT}}} \right)y(1 - y)$$ and that for the latter 50% mass-loss of HNNC described by the reaction equations $$\frac{{dy}} {{dy}} = - 10^{16.3} \exp \left( { - \frac{{169483}} {{RT}}} \right)y\quad (n = 1)$$ and $$\frac{{dy}} {{dt}} = - 10^{16.8} \exp \left( { - \frac{{165597}} {{RT}}} \right)y^{2.61} \quad (n \ne 1)$$
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    Positronium Conversion Reactions for Testing the Electron Delocalization in 3d Complexes Caused by Ligands (1998)
    Springer
    Structural chemistry 9 (1998), S. 389-394 
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    ISSN: 1572-9001
    Keywords: Positronium chemistry ; kinetics ; spin exchange reactions ; paramagnetic 3d complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The rate constants of ortho- into para-positronium conversion reactions promoted by paramagnetic 3d complexes were found to be linearly correlated with the delocalization, β of unpaired metal electrons caused by ligands. It is shown here that βs, usually obtained by UV/Vis absorption spectroscopy, may also be deduced from the correlations mentioned above.
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    Kinetic On-line Evaluation of Chemical Reactions (1998)
    Springer
    Journal of thermal analysis and calorimetry 52 (1998), S. 187-194 
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    ISSN: 1572-8943
    Keywords: calorimetry ; kinetics ; on-line ; optimization ; software
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A computer program was developed for kinetic evaluations of calorimetric experiments to predict the further reaction run under adiabatic conditions. Kinetic modeling is based on elementary reaction steps whose rate laws form a set of differential equations. For the continuous parameter optimization time-temperature data and their derivatives are used. A special calorimeter of the ACTRON series with safety equipment was applied to investigate the kinetics of chemical reactions and to test kinetic on-line evaluations. In the paper, examples for the reaction of n-propanol with o-chlornitrobenzene and for the alcoholysis of phenyl isocyanate are given.
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    The cis-trans Isomerization of Azobenzene in the Molten State: A useful test reaction for the kinetic evaluation of DSC measurements (1998)
    Springer
    Journal of thermal analysis and calorimetry 52 (1998), S. 177-185 
    Details
    ISSN: 1572-8943
    Keywords: azobenzene ; DSC ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Contrary to the situation in the field of temperature, heat and heat flow rate calibration, so far no generally accepted and easily practicable chemical reaction exists with regard to a kinetic evaluation. A possible reaction would be the well-known first-order cis-trans isomerization of subcooled liquid azobenzene. Surprisingly, the evaluation of measurements performed with a power compensated calorimeter yields activation parameters, which are dependent on the heating rate. The desmearing of the curves does not produce any improvements. However, constant activation parameters are obtained, if a small self-heating of the sample during the exothermic reaction is taken into account.
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    Thermal Decomposition Kinetics of Lanthanum Complexes of 1,2-(Diimino-4'-Antipyrinyl)ethane (1998)
    Springer
    Journal of thermal analysis and calorimetry 52 (1998), S. 475-480 
    Details
    ISSN: 1572-8943
    Keywords: complexes of lanthanum ; entropy of activation ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics and mechanism of the thermal decomposition of perchlorate, nitrate and iodide complexes of lanthanum with the Schiff base 1,2-(diimino-4'-antipyrinyl)ethane (abbreviated as GA) have been studied by TG and DTG techniques. The kinetic parameters like the activation energy, the pre-exponential factor and the entropy of activation were calculated for the major decomposition stages (Stages I and II) using Coats-Redfern equation. The rate controlling process obey ‘Mampel model’ with random nucleation with one nucleus on each particle. The kinetic parameters indicate that the ligands are loosely bound to metal ion and the activated complex formed in the decomposition reaction is more ordered than the reactants.
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    Considerations on the Thermal Behaviour and Oxidation Resistance of Cast Iron (1998)
    Springer
    Journal of thermal analysis and calorimetry 52 (1998), S. 425-438 
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    ISSN: 1572-8943
    Keywords: kinetics ; nodular cast iron ; TG-DTG-DTA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermal analysis was used to characterize the thermal behaviour and oxidation resistance of some nodular cast irons. Samples of nodular cast iron in various stages of elaboration, with different chemical compositions, were studied. The samples were heated in air, in the temperature range 291-1273 K, and the thermal (TG, DTG and DTA) curves were recorded. A group of samples with low silicon content exhibit similar behaviour: a continuous increase in mass and an exothermic effect up to 1123 K. The thermal effects correspond to iron oxide (Fe3O4, FeO, Fe2O3) formation. At high temperatures (T〉1123 K), there is a decrease in mass and an endothermic effect. A decrease in the superficial carbon content by combustion (‘decarburization’ effect) occurs in the range of high temperatures. The two effects of oxidation and decarburization depend on the structural changes which occur in cast iron at high temperatures. The decarburization process was modelled and the kinetic parameters were determined (reaction order n=0.76; activation energy E=141 kJ mol-1; pre-exponential factor A=2·102s-1). The oxidation process was studied by non-isothermal methods with regard to two mechanisms: two-dimensional transport for low temperatures, and three-dimensional transport through a sphere for high temperatures. The activation energies were calculated: 68 kJ mol-1 for low temperatures and 122 kJ mol-1 for high temperatures.
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    Mechanism and Kinetics of Thermal Dissociation of Inclusion Complex of Benzaldehyde with β-Cyclodextrin (1998)
    Springer
    Journal of thermal analysis and calorimetry 53 (1998), S. 825-833 
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    ISSN: 1572-8943
    Keywords: benzaldehyde ; β-cyclodextrin ; inclusion complex ; kinetics ; mechanism ; thermal dissociation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The inclusion complex of benzaldehyde (BA) with β-cyclodextrin (β-CD) was prepared and was studied by thermal analysis and X-ray diffractometry. The composition of the complex was identified by TG and elemental analysis as β-CD·BA·9H2O. TG and DSC studies showed that the thermal dissociation of β-CD·BA·9H2O took place in three stages: dehydration in the range 70-120°C; dissociation of β-CD·BA in the range 235-270°C; and decomposition of β-CD above 280°C. The kinetics of dissociation of β-CD·BA in flowing dry nitrogen was studied by means of TG both at constant temperature and at linearly increasing temperature. The results showed that the dissociation of β-CD·BA was dominated by a one-dimensional random nucleation and subsequent growth process (A2). The activation energy E was 124. 8 kJ mol-1, and the pre-exponential factor A 5.04·1011 min-1.
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    The Non-Parametric Kinetics A New Method for the Kinetic Study of Thermoanalytical Data (1998)
    Springer
    Journal of thermal analysis and calorimetry 52 (1998), S. 933-943 
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    ISSN: 1572-8943
    Keywords: kinetics ; non-parametric kinetics method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The application of the new method non-parametric kinetics for kinetic analysis is discussed. It is shown that this method is able to obtain all the kinetic information needed to reproduce accurately the experimental data. To validate this method a set of numerical simulations of the most commonly used kinetic models has been performed and analysed with the method.
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    Oxidation of Saturated Fatty Acids Esters DSC investigations (1998)
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    Journal of thermal analysis and calorimetry 54 (1998), S. 211-217 
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    ISSN: 1572-8943
    Keywords: DSC ; fatty acids esters ; kinetics ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Oxidation of saturated fatty acids ethyl esters: laurate, myristate, palmitate and stearate was investigated by means of DSC techniques under isothermal and non-isothermal conditions. The activation energies of isothermal oxidation were similar to each other (112–123 kJ mol−1) and no influence of carbon length on the rate of oxidative decomposition was observed. Results obtained from non-isothermal experiments were similar only for the first stage of oxidation.
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    ASTM Kinetics of Oil Shales (1998)
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    Journal of thermal analysis and calorimetry 53 (1998), S. 567-575 
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    ISSN: 1572-8943
    Keywords: combustion ; differential scanning calorimeter ; kinetics ; oil shale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermal analysis is increasingly being used to obtain kinetic data relating to sample decomposition. In this research differential scanning calorimeter (DSC) was used to determine the combustion kinetics of three (Çan, Himmetoglu and Mengen) oil shale samples by ASTM and Roger & Morris methods. On DSC curves two reaction regions were observed on oil shale sample studied except Çan oil shale. In DSC experiments higher heating rates resulted in higher reaction temperatures and higher heat of reactions. Distinguishing peaks shifted to higher temperatures with an increase in heating rate. Three different kinetic models (ASTM I-II and Rogers & Morris) were used to determine the kinetic parameters of the oil shale samples studied. Activation energies were in the range of 131.8-185.3 kJ mol-1 for ASTM methods and 18.5-48.8 kJ mol-1 for Rogers & Morris method.
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    Thermal Analysis and Kinetic Study of Decomposition processes of Some Commercial Pesticides I. Triazine derivatives (1998)
    Springer
    Journal of thermal analysis and calorimetry 53 (1998), S. 937-956 
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    ISSN: 1572-8943
    Keywords: enthalpy ; GC—MS measurements ; kinetics ; simultaneous TG—DSC ; thermal stability ; 1,3,5 triazine derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal behaviour of some commercial pesticides was studied by means of simultaneous TG-DSC measurements. Kinetic parameters relating to liquid—gas-phase transition processes were determined via a dynamic TG technique. Gas chromatography-mass spectrometry were used to make measurements on the gaseous products. The liquid—gas-phase transition processes of these compounds seem to be influenced by the substituent groups rather than by the side-chains. A chlorine substituent destabilizes some compounds, bringing closer together the temperatures of melting and liquid—gas-phase transition processes.
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    Spectroscopic and Thermal Studies on 2,4,6-trinitro Toluene (TNT) (1999)
    Springer
    Journal of thermal analysis and calorimetry 55 (1999), S. 173-185 
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    ISSN: 1572-8943
    Keywords: IRS ; kinetics ; mechanism ; nitro aromatic ; TA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics and mechanism of the initial stage of thermal decomposition of 2,4,6-trinitro toluene (TNT), a widely used high explosive, have been studied, together with its morphology and evolved gaseous products using thermogravimetry (TG), differential thermal analysis (DTA), infrared spectroscopy (IR) and hot-stage microscopy. The kinetics of the thermolysis has been followed by IR after suppressing volatilisation by matrixing and by isothermal TG without suppressing volatilisation to simulate actual user conditions. The best linearity was obtained for Avrami-Erofeev equation for n=1 in isothermal IR and also in isothermal TG. The activation energy was found to be 135 kJ mol−1, with logA (in s−1) 12.5 by IR. The effect of additives on the initial thermolysis of TNT has also been studied. Evolved gas analysis by IR showed that CO2, NO2, NO and H2O are more dominant than N2O, HCN and CO. The decomposition involves the initial rupture of the C-NO2 bond, weakened by hydrogen bonding with the labile hydrogen atom of the adjacent CH3 group, followed by the abstraction of the hydrogen atom of the methyl group by NO2, generated in the initial step.
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    Thermal Decompositions of (RE)Ba2Cu3O6 (RE=Y, Nd, Er) (1999)
    Springer
    Journal of thermal analysis and calorimetry 55 (1999), S. 691-698 
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    ISSN: 1572-8943
    Keywords: activation energy ; kinetics ; solid-state reactions ; superconductors ; thermogravimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermogravimetric in situ measurements of oxygen loss from (RE)Ba2Cu3O6 samples (RE=Y, Nd, Er) heated isothermally in a relatively high dynamic vacuum were made with a Cahn RG electrobalance. Single-phase orthorhombic samples of composition (RE)Ba2Cu3O7-x (highest oxygen content) were synthesized from stoichiometric (1:2:3) mixtures of high-purity (RE)2O3, BaCO3 and CuO. The original 1:2:3 mixture was prepared by the two-stage procedure described earlier. The crystal structure of the sample in the original orthorhombic phase was controlled by the X-ray powder method (CuKα radiation) using a Stadi P Stoe diffractometer with a position-sensitive detector. The decomposition curves are described by the sum of exponential terms corresponding to rapid and slow first-order processes in which differently sized grains of the powder samples are involved. The activation energies are estimated from appropriate Arrhenius plots.
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    Thermal Decompositions of the Molybdotellurates of Nickel(II) and Cobalt(II) (1999)
    Springer
    Journal of thermal analysis and calorimetry 55 (1999), S. 779-788 
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    ISSN: 1572-8943
    Keywords: cobalt ; dynamic and isothermal methods ; kinetics ; molybdotellurates ; nickel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Molybdotellurates [M(H2O)6]3·[TeMo6O24], with M=Ni(II) and Co(II), were synthesized and characterized by single-crystal X-ray diffraction for compound 1 and X-ray powder diffraction for compound 2, EDAX, IR, electronic spectra in the solid phase and in solution, and magnetic properties. Thermogravimetry and differential scanning calorimetry of both compounds revealed a loss of 11 water molecules through an endothermal process with ΔH=800 kJ mol−1 for the nickel compound and ΔH=833 kJ mol−1 for the cobalt compound. The residual compounds were characterized by chemical analysis, IR and XPS spectroscopy
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    Physicochemical Studies and Thermal Decomposition Kinetics of Co(II), Ni(II), Cu(II) and Zn(II) Complexes of Citronellal Anthranilic Acid (1999)
    Springer
    Journal of thermal analysis and calorimetry 55 (1999), S. 817-831 
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    ISSN: 1572-8943
    Keywords: kinetics ; Schiff-bases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Cobalt(II), nickel(II), copper(II) and zinc(II) complexes of two new Schiff-bases, citronellal anthranilic acid and citronellal-5-bromoanthranilic acid have been synthesized. On the basis of spectral, magnetic and thermal data, octahedral structure was assigned to all complexes [ML2(H2O)2]. Thermal decomposition of these complexes was studied by TG. Kinetic parameters, viz activation energy, E, pre-exponential factor, A, and order of reaction, n, were calculated from the TG curves using mechanistic and non-mechanistic integral equations.
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    RCTA Techniques Used in Studies of Solid State Reactions in Inorganic Compounds (1999)
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    Journal of thermal analysis and calorimetry 56 (1999), S. 17-26 
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    ISSN: 1572-8943
    Keywords: kinetics ; reaction controlled thermal analysis ; stepwise isothermal analysis ; thermogravimetry
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The Reaction Controlled Thermal Analysis techniques, RCTA, are very useful both in thermogravimetric and dilatometric studies. In the present paper this big family of techniques is divided into three main classes: Quasi-Isothermal techniques (QIA); Controlled Reaction Rate Thermal Analysis (CRTA) and Reaction (Event) Controlled Heating Rate Adaption. After a short presentation of these techniques and the general advantages of RCTA, two examples of kinetic studies on thermal decomposition of Ba- and Ce oxalates by using Stepwise Isothermal Analysis, SIA, introduced by the author is presented and discussed.
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    Isothermal and Non-Isothermal Kinetics When Mechanistic Information Available (1999)
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    Journal of thermal analysis and calorimetry 56 (1999), S. 783-792 
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    ISSN: 1572-8943
    Keywords: complex process ; DSC ; isoconversional methods ; kinetics ; model-free kinetics ; peak maximum evolution methods ; simulations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In the case of a complex mechanism of two parallel independent reactions, peak maximum evolution methods and model-fitting methods give only a mean value of the kinetic parameters, while isoconversional methods are useful to describe the complexity of the mechanism. Isothermal and non-isothermal isoconversional methods can be used to elucidate the kinetics of the process. Nevertheless, isothermal isoconversional methods can be limited by restrictions on the temperature regions experimentally available because of duration times or detection limits.
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    Kinetic Study of Thermal Decomposition of the DMIT Complex of Cobalt (1999)
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    Journal of thermal analysis and calorimetry 56 (1999), S. 805-810 
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    Keywords: cobalt ; dmit ligand ; kinetics ; non-linear method ; Zsakó method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In this work, a cobalt complex with dmit (1,3-dithiol-2-thione-4,5-dithiolate) as ligand was prepared and its thermal stability was studied by thermogravimetric analysis and kinetics by means of the Zsakó method and a non-linear method. For both methods, numerical binomial and polynomial filters were used, where points in the central interval were utilized.
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    DSC Analysis of the Induction Period in the Vulcanisation of Rubber Compounds (1999)
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    Journal of thermal analysis and calorimetry 56 (1999), S. 1107-1113 
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    ISSN: 1572-8943
    Keywords: differential scanning calorimetry ; induction period ; kinetics ; vulcanisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Vulcanisation of rubber compounds was studied by DSC under isothermal and non-isothermal conditions. The parameters of an Arrhenius-like equation describing the temperature dependence of induction period have been obtained both from isothermal and non-isothermal measurements. A new method for obtaining the kinetic parameters from non-isothermal measurements, based on the dependence of onset temperature of vulcanisation peak on heating rate, is presented. Also, a procedure for the evaluation of temperature difference between the furnace and sample is proposed. It has been shown that the treatment of non-isothermal DSC measurements gives the kinetic parameters free of systematic errors. The new method can also be used for studying other reactions exhibiting the induction period.
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    Kinetics and Mechanism of Dehydration of Heteropolyacids (1998)
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    Journal of thermal analysis and calorimetry 53 (1998), S. 235-239 
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    Keywords: decomposition ; dehydration ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics and mechanism of the dehydration and decomposition of heteropolyacids of molybdenum, tungsten and vanadium (H3+xYx+M12O40·mH2O; Y=Si, P; M=Mo, W) were studied. The data obtained on the dehydration kinetic parameters correlate with the expected structures, of these crystal hydrates, the IR data and X-ray phase analysis.
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    Kinetics and Mechanism of the Oxidation of Molybdenum Sulphide (1998)
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    Journal of thermal analysis and calorimetry 53 (1998), S. 263-267 
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    ISSN: 1572-8943
    Keywords: kinetics ; molybdenum sulphide ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This paper reports on the results attained in the determination of the mechanism of oxidation of molybdenum sulphide under non-isothermal conditions in an air atmosphere. The mechanism of the process was determined by simultaneous DTA-TG-DTG, and the kinetic parameters of the reactions involved were obtained according to the methods of Kissinger and Ozawa.
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    Kinetics and Mechanism of the Thermal Decomposition of M(NO3)2·nH2O (M=Cu, Co, Ni) (1998)
    Springer
    Journal of thermal analysis and calorimetry 53 (1998), S. 617-623 
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    ISSN: 1572-8943
    Keywords: kinetics ; nitrates ; thermal decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This paper presents the results of simultaneous DTA-TG-DTG and DSC studies on the thermal decomposition of Cu(NO3)2·3H2O, Co(NO3)2·6H2O and Ni(NO3)2·6H2O in an air atmosphere. The mechanism and enthalpies of the investigated processes were determined, as well as the kinetic parameters of the processes run under non-isothermal conditions by means of Kissinger's method. The dependence of the activation energy on the ionic radius of the cations building up the crystal lattices of the investigated compounds was also studied.
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    Pyrolysis Analysis and Kinetics of Crude Oils (1998)
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    Journal of thermal analysis and calorimetry 52 (1998), S. 781-788 
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    ISSN: 1572-8943
    Keywords: crude oil ; differential scanning calorimetry ; kinetics ; pyrolysis ; thermal analysis ; thermogravimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This research presents the results of an experimental study on the determination of pyrolysis behaviour and kinetics of six crude oils by differential scanning calorimetry (DSC) and thermogravimetry (TG/DTG). Crude oil pyrolysis indicated two main temperature ranges where loss of mass was observed. The first region between ambient to 400°C was distillation. The second region between 400 and 600°C was visbreaking and thermal cracking. Arrhenius-type kinetic model is used to determine the kinetic parameters of crude oils studied. It was observed that as crude oils gets heavier (°API decreases) cracking activation energy increases. Activation energy of cracking also show a general trend with asphaltene content.
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    A Theoretical Approach to the Description of the Thermal Dissociation of N,N,N-Trimethylmethanaminium Halides (1998)
    Springer
    Journal of thermal analysis and calorimetry 54 (1998), S. 189-195 
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    ISSN: 1572-8943
    Keywords: decomposition ; kinetics ; N,N,N-trimethylmethanaminium halides ; theory ; thermodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract MNDO/d and PM3 quantum chemistry methods were used to examine reaction pathways and predict thermodynamic and kinetic barriers for the thermal dissociation of isolated conglomerates of N,N,N-trimethylmethanaminium cations (TMA+) and halide anions (X = Cl−, Br− and I−). Theoretically obtained changes in enthalpy and entropy for the above-mentioned process were subsequently supplemented with theoretically determined crystal lattice energies, that enabled prediction of relevant characteristics for the dissociation of crystalline phases. Data thus obtained compare only qualitatively with those available in literature and resulting predominantly from thermoanalytical investigations, although values of theoretical characteristics generally follow the same trends as experimental ones.
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    Kinetics and Mechanism of the Natural Mineral Marmatite Oxidation Process (1998)
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    Journal of thermal analysis and calorimetry 54 (1998), S. 35-40 
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    ISSN: 1572-8943
    Keywords: kinetics ; marmatite ; oxidation process
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Results obtained by the comparative investigations of the natural mineral marmatite (Zn,Fe)S (Stari Trg, Yugoslavia) oxidation process are presented in this paper. Determination of the oxidation process mechanism was done by thermal analysis methods: DTA-TG-DTG and DSC, while Mössbauer spectroscopy, X-ray and electronic microanalysis were used for phase composition determination of the products formed during the oxidation process. Kinetics of the process was defined for two temperature intervals 862–973 and 1023–1173 K, under isothermal conditions.
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    Determination of the Kinetic Parameters of Chemical Reactions on the Basis of Non-Isothermal Measurements A critical review (1998)
    Springer
    Journal of thermal analysis and calorimetry 54 (1998), S. 399-406 
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    Keywords: activation energy ; kinetics ; non-isothermal measurements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A detailed analysis is presented of the applicability of several dependences commonly used for the determination of activation energies from non-isothermal measurements. Reactions proceeding according to different kinetic equations are simulated and the validity of the activation energy values obtained is discussed. The general conclusion is drawn that none of the examined dependences should be used to determine the activation energy. For a rough estimation of activation energy, the Kissinger equation can be applied according to Ockham's razor.
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    Investigation of Kinetics of Solid-Phase Synthesis of Lithium Orthosilicate (1999)
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    Journal of thermal analysis and calorimetry 55 (1999), S. 699-705 
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    ISSN: 1572-8943
    Keywords: interaction in solid phase ; lithium carbonate ; lithium orthosilicate ; kinetics ; solid electrolytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of the interaction between lithium carbonate and silica with various degrees of dispersion was investigated by TG and DTA methods. It was found that the utilization of pyrogenic silica with a specific surface area of about 300 m2g-1 instead of aerosil with one of 175 m2g-1 leads to an increase of the reaction rate between lithium carbonate and silica, which depends on the formation and growth of lithium orthosilicate crystals in the first stage, and is conditioned by the diffusion of lithium and oxygen ions through the lithium orthosilicate layer formed at temperatures above 800 K. This supposition is supported by the kinetic analysis results obtained with the use of the different models. The optimal regime of heating is recommended.
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    Crystallization Kinetics of Lithium Diborate Glass by DTA (1999)
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    Journal of thermal analysis and calorimetry 56 (1999), S. 755-761 
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    ISSN: 1572-8943
    Keywords: crystallization ; DTA ; kinetics ; Kissinger plot ; lithium diborate glass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystallization process of Li2B4O7 in the glass of stoichiometric composition, characterized by the crystal growth of pre-existing nuclei, was analyzed kinetically by means of DTA. Because the number of pre-existing nuclei for the subsequent growth varies depending on the cooling rate of the glass-forming melt and heating rate of the as-prepared glass, a modified Kissinger plot was applied for evaluating the apparent activation energy to the crystal growth in the glass samples with three different thermal histories, i.e., the pre-annealed, slowly quenched and quickly quenched glasses. The process was characterized by the three dimensional growth of pre-existing nuclei with the apparent activation energy of ca 340 kJ mol−1.
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    A Dilatometric Investigation of the Thermal Compaction of Ferrite Powders Prepared by Coprecipitation (1999)
    Springer
    Journal of thermal analysis and calorimetry 56 (1999), S. 603-610 
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    ISSN: 1572-8943
    Keywords: coprecipitation ; ferrite ; kinetics ; sintering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The authors report on a non-isothermal kinetic investigation (at constant heating rate) of the sintering of manganese and nickel-zinc ferrite powders prepared by coprecipitation. The kinetic results point to the thermal compaction of the powders, which occurs mainly in the intermediate stage of sintering. A comparative study was performed in order to determine the influence of the sample characteristics (such as chemical nature, density and shape) and the heating rate on the kinetics and mechanism of the compaction.
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    Progress in Non-parametric Kinetics (1999)
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    Journal of thermal analysis and calorimetry 56 (1999), S. 843-849 
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    Keywords: adiabatic calorimetry ; kinetics ; non-parametric kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The non-parametric kinetics (NPK) method has been recently developed for the kinetic treatment of thermoanalytical data. The most significant feature of this method is its ability to provide information about the reaction kinetics without any assumptions either about the functionality of the reaction rate with the degree of conversion or the temperature. This paper presents the results of the application of the method to adiabatic calorimetry. Some data have been obtained by numerical simulation, but also the thermal decomposition of DTBP, a well known first order reaction, has been studied, being the obtained results in good agreement with literature.
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    Kinetics of Thermal Decomposition of Dolomite (1999)
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    Journal of thermal analysis and calorimetry 56 (1999), S. 829-833 
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    Keywords: dolomite ; kinetics ; thermal decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal decomposition reactions of calcitic dolomite were investigated. Simultaneous TG/DTG/DTA were applied under non-isothermal conditions. From the recorded curves, the activation energies, pre-exponential factors and thermodynamic parameters of activation were calculated for the two thermal decomposition steps.
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    Determination of Activation Energies by Using Different Factors Φ in Adiabatic Calorimetry (1999)
    Springer
    Journal of thermal analysis and calorimetry 58 (1999), S. 215-223 
    Details
    ISSN: 1572-8943
    Keywords: adiabatic calorimetry ; kinetics ; Kissinger method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Traditionally, the kinetic treatment of adiabatic calorimetry data has been based on the results of one or more experiments, but always with the assumption of the kinetic model that the reaction follows to calculate the kinetic parameters. In this paper a method for the determination of the activation energy that uses a set of adiabatic calorimetry data is developed. To check the method, the thermal decompositions of two peroxides were studied.
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    CRTA for the Thermoanalytical Screening of Volatile Compounds: 3. Study on thermal destruction process, taking place simultaneously with evaporation process (1999)
    Springer
    Journal of thermal analysis and calorimetry 58 (1999), S. 113-116 
    Details
    ISSN: 1572-8943
    Keywords: coordinationcompounds ; CRTA ; kinetics ; polymerization ; pyrolysis ; quasi-equilibrium ; TG ; thermolysis ; volatility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Quasi-equilibrium thermogravimetry (variant of CRTA) is put to use as an express method of thermoanalytical screening for volatile compounds. During the experiments for P—T relationship calculations (running with several calibrated standard sample holders) the non-volatile (polymerized) residue is formed (and is decomposed with further temperature rising). Thermogravimetric data are used for the calculation of the kinetic parameters for the polymerization reaction, taking place (concurrently with the evaporation) in the melt of the studied volatile compound.
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    URL: http://dx.doi.org/10.1023/A:1010183601559
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    Study of the Kinetics of the Combustion Reaction on Shuangya Mountain Coal Dust by TG (1999)
    Springer
    Journal of thermal analysis and calorimetry 58 (1999), S. 447-453 
    Details
    ISSN: 1572-8943
    Keywords: coal ; combustion reaction ; kinetics ; TG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The combustion behavior of Shuangya Mountain (SYM) coal dust has been investigated by means of TG in this paper. The reaction fraction α can be obtained from isothermal TG data. The regressions of g(α), an integral function of α vs. t for different reaction mechanisms were performed. The mechanism of nucleation and nuclei growth is determined as the controlling step of the coal dust combustion reaction by the correlation coefficient of the regression, and the kinetic equation of the SYM coal dust combustion reaction has been established.
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    URL: http://dx.doi.org/10.1023/A:1010123809663
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    Electron Delocalization in 3d Complexes Caused by Dimethylurea Checked by Positron Annihilation (1999)
    Springer
    Structural chemistry 10 (1999), S. 433-437 
    Details
    ISSN: 1572-9001
    Keywords: Positronium Chemistry ; kinetics ; spin exchange reactions ; paramagnetic 3d complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The rate constants, k CR, of ortho- into para-positronium conversion reactions promoted by paramagnetic 3d complexes are linearly correlated with the electron delocalization, β, of unpaired metal electrons caused by ligands, β being the ratio between the inter-electronic repulsion parameters in complexes and in the free gaseous ions. By applying a procedure previously described the β values of MnII, CoII, NiII complexes with dimethylurea were deduced from the mentioned correlations and compared with those of complexes with urea obtained both by the method of Ps reactions here applied and that based on UV-Vis absorption spectroscopy.
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    URL: http://dx.doi.org/10.1023/A:1022479106226
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    Tetrachlorosilane Consumption in Radio Frequency Glow Discharge (1998)
    Springer
    Plasma chemistry and plasma processing 18 (1998), S. 509-533 
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    ISSN: 1572-8986
    Keywords: RF SiCl4 discharge ; mass spectrometry ; kinetics ; decomposition ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Time-resolved mass spectrometry was used for analysis of the plasma reactions in radio frequency (RF) SiCl 4 and SiCl 4 −O 2 discharges as functions of starting partial pressure and electrical power. Molecular concentrations of the reactants and products from SiCl 4 alone and with O 2 were obtained from the mass spectra and used for plotting the kinetic curves. The SiCl 4 and O 2 consumption rates were calculated from the kinetic curves and compared with results of theoretical simulation of the reaction. Direct electron impact decomposition was found to be the main pathway for pure SiCl 4 conversion. On the contrary, the consumption of SiCl 4 in the SiCl 4 +O 2 mixtures was largely chemical. The experimental macrokinetics are in agreement with a model in which oxidation is caused by the atomic oxygen.
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    Investigation of the Chemical Action of the Gliding and “Point” Arcs Between the Metallic Electrode and Aqueous Solution (1999)
    Springer
    Plasma chemistry and plasma processing 19 (1999), S. 53-67 
    Details
    ISSN: 1572-8986
    Keywords: Arc ; gliding arc ; gas temperature ; electron temperature ; ion composition ; ion bombardment ; liquid electrode ; dye oxidation ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The plasma–solution interaction processes for gliding and “point” arcs between the aqueous solution surface and the metal electrode in the gas phase are studied. The plasma, liquid, and surface zones are taken into consideration. The electric field strength is measured, and the gas and electron temperatures and ion composition are estimated for the plasma zone. The cathode fall, water vaporization rate, and active species current yield due to the radiation chemistry mechanism are determined for the surface zone. The efficiency of oxidation of iodine ions and organic dyes by different types of discharge in the liquid zone are investigated. The difference in action of the various discharge types may be connected with various influences of the plasma and surface zone on the oxidation processes.
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    URL: http://dx.doi.org/10.1023/A:1021803932496
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    Study of the Influence of Alkaline Ions (Li, Na and K) on the Structure of the Silicate Entities in Silico Alkaline Sol and on the Formation of the Silico-Calco-Alkaline Gel (1998)
    Springer
    Journal of sol gel science and technology 13 (1998), S. 353-358 
    Details
    ISSN: 1573-4846
    Keywords: silicate ; alkaline ; gelation ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The study of silico-calco-alkaline gel is essential to warn against the degradation of concrete due to the alkali-silica reaction. In the laboratory, those gels are simulated by the destabilization of a silico-alkaline sol by calcium ions. Their speed of formation depends on the alkali species. The influence of alkaline ions (Li, Na and K) on the structure of silicate entities in sol and on the gel formation has been studied. The state of polymerization of the silico-alkaline sol was determined by NMR and depends on the alkali species and the molar ratio (Rm = [SiO2]/[A2O] with A = Li, Na or K). It appears that lithium enhances the polymerization. By scattering techniques (SAXS and ELS), the evolution of size and number of scattering particles during gelation can be determined from scattering curves with Guinier approximation. The mechanism of gelation appears as a hierarchic structure composed of several discrete sizes.
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    URL: http://dx.doi.org/10.1023/A:1008644405473
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    Kinetics of Solid State Reactions With Fractal Reagent (1998)
    Springer
    Journal of materials synthesis and processing 6 (1998), S. 305-309 
    Details
    ISSN: 1573-4870
    Keywords: Fractals ; solid state reaction ; kinetics ; nucleation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In the present research we theoretically studied the kinetics of nucleation-limited solid state reactions as influenced by the fractal properties of solid reagent. We consider the model of equal-sized primary particles assembled in fractal cluster. The geometry of such an object is assumed to be described solely by its fractal dimension D and by upper (R max) and lower (R min) cutoffs of fractality further identified with the overall size of the object and the size of the primary particle correspondingly. Depending on the ratio between R max, R min and the radius of the critical nucleus R nucl the following cases are considered: (1) R max ∼ R nucl. In this case the reaction kinetics is described by the equation: α = 1 − B{ln(k′ τ + 1)}D/(D−3), where B, k′ are constants. Numerical solution of this equation gives rise to n-order reaction kinetics with n & 1. (2) R min ≪ R nucl ≪ R max. In this case under certain conditions there can exist non-trivial critical density ρcrit ≠ 0, 1 that favors the formation of the critical nuclei of the new phase. The asymptotic kinetic equation for large times corresponds to n-order reaction with n = (D + 3)/(D + 1). (3) R min ≪ R nucl ∼ R max′. In this case the reaction follows the first-order kinetics with D-dependent rate constant.
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    Effects of phosphatidylinositol 4,5-bisphosphate and neomycin on phospholipase D: Kinetic studies (1999)
    Springer
    Molecular and cellular biochemistry 197 (1999), S. 195-201 
    Details
    ISSN: 1573-4919
    Keywords: phospholipase D ; phosphatidylinositol 4,5-bisphosphate ; neomycin ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The kinetics of phosphatidylcholine-specific phospholipase D activated by phosphatidylinositol 4,5-bisphosphate (PIP2) and inhibition by neomycin were studied in an enzyme preparation partially purified from human hepatocarcinoma cell line. It was found that phospholipase D was marginally activated by phosphatidyl-4-phosphate (PIP) and phosphatidylethanolamine (PE). In contrast, it was considerably activated by PIP2 in different concentration of phosphatidylcholine (PC). Sphingomyelin (SM), lysophosphatidylcholine (LPC) and phosphatidylserine (PS) were neither substrates nor inhibitors of the phospholipase D. PIP2 induced an allosteric effect on phospholipase D and a negative cooperative effect with respect to phosphatidylcholine as indicated in the Lineweaver-Burk plot. In the absence of PIP2, a straight line was obtained, whereas a downward concave curve was observed in the presence of 25 μM of PIP2. The Hill coefficient and the apparent Km of phosphatidylcholine in the presence of 25 μM PIP2 were calculated to be 0.631 and 10.79 mM, respectively. PIP2 also increased the maximal velocity (Vmax) of the phospholipase D reaction, suggesting that the affinity of substrate to enzyme was decreased, and the turnover number of the enzyme (kcat) was increased by PIP2. The activation of phospholipase D by PIP2 was dose dependent up to 50 μM of PIP2. The Ka of PIP2 was 15.8 mM. Neomycin, a polycationic glycoside, was shown to be an uncompetitive inhibitor of phospholipase D, and revealed the formation of a neomycin-PIP2 complex. The Ki of neomycin was estimated to be 8.7 mM.
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    The Kinetics of Pore Shape Evolution in Alumina (1998)
    Springer
    Journal of materials synthesis and processing 6 (1998), S. 161-167 
    Details
    ISSN: 1573-4870
    Keywords: Alumina ; surface ; kinetics ; diffusion ; SALK
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The kinetics of shape evolution of a completely faceted crystal/internal void by surface diffusion was modeled. Arrays of micron-sized cavities were generated in sapphire substrates with known surface orientations using microlithography and ion beam etching and converted to internal intragranular pores of nonequilibrium shape by diffusion bonding of the etched substrate to an identical-orientation unetched sapphire substrate. Pore shape evolution rates during high-temperature anneals were monitored and found to be highly sensitive to the orientation of the substrate surface. The observed evolution rates were compared with the predictions of the kinetic model using diffusivity values for alumina that span the range from the highest to the lowest diffusion constants reported in the literature. The comparison suggests that surface-attachment-limited kinetics (SALK) play a major role in surface mass transport on stable low-index planes of alumina.
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    Regulatory mechanisms of poly(ADP-ribose) polymerase (1999)
    Springer
    Molecular and cellular biochemistry 193 (1999), S. 19-22 
    Details
    ISSN: 1573-4919
    Keywords: poly(ADP-ribose)polymerase ; kinetics ; allosterism ; regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Here, we describe the latest developments on the mechanistic characterization of poly(ADP-ribose) polymerase (PARP) [EC 2.4.2.30], a DNA-dependent enzyme that catalyzes the synthesis of protein-bound ADP-ribose polymers in eucaryotic chromatin. A detailed kinetic analysis of the automodification reaction of PARP in the presence of nicked dsDNA indicates that protein-poly(ADP-ribosyl)ation probably occurs via a sequential mechanism since enzyme-bound ADP-ribose chains are not reaction intermediates. The multiple enzymatic activities catalyzed by PARP (initiation, elongation, branching and self-modification) are the subject of a very complex regulatory mechanism that may involve allosterism. For instance, while the NAD+ concentration determines the average ADP-ribose polymer size (polymerization reaction), the frequency of DNA strand breaks determines the total number of ADP-ribose chains synthesized (initiation reaction). A general discussion of some of the mechanisms that regulate these multiple catalytic activities of PARP is presented below.
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    Evidence for O-dealkylation of 7-pentoxyresorufin by cytochrome P450 2B1/2B2 isoenzymes in brain (1998)
    Springer
    Molecular and cellular biochemistry 189 (1998), S. 201-205 
    Details
    ISSN: 1573-4919
    Keywords: brain ; P450 ; PB ; PROD ; induction ; inhibition ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract O-dealkylation of 7-pentoxyresorufin (PR) was studied in rat brain to characterise the functional activity specific for cytochrome P450 2B1/2B2 isoenzymes in brain microsomes. Brain microsomes catalyzed the O-dealkylation of PR in the presence of NADPH. Pretreatment with phenobarbital (PB; 80 mg/kg body wt, i.p.× 5 days) resulted in 3-4 fold induction of pentoxyresorufin-O-dealkylase (PROD) activity while 3-methylcholanthrene (MC; 30 mg/kg body wt, i.p. × 5 days) did not produce any significant increase in enzyme activity. Kinetic studies revealed that the rate of velocity (Vmax) for the O-dealkylation of PR was significantly increased to 2.9 times higher in brain microsomes isolated from PB pretreated rats. In vitro studies using metyrapone, an inhibitor of P450 2B1/2B2 catalyzed reactions and antibody for hepatic PB inducible P450s (P450 2B1/2B2) significantly inhibited the activity of PROD in cerebral microsomes prepared from PB pretreated animals. These studies suggest that PB inducible isoenzymes of P450, i.e. P450 2B1/2B2 specifically catalyze the O-dealkylation of PR in brain microsomes.
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    Kinetic Studies on the Initial Crystallization Process of Lysozyme in the Presence of D2O and H2O (1998)
    Springer
    The protein journal 17 (1998), S. 9-14 
    Details
    ISSN: 1573-4943
    Keywords: Lysozyme ; turbidity ; kinetics ; nucleation ; relaxation time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In the initial stages of the crystallization of egg-white lysozyme, monomeric lysozyme aggregates rapidly and forms a nucleus in the presence of high salt concentrations. The formation process of the aggregates was examined to make clear the difference between the situations in heavy water and in water at the same sodium ion concentration. The aggregation in both cases was observed at unsaturated and/or saturated lysozyme concentrations. The turbidity at 350 nm of lysozyme increased remarkably within 60 min under each experimental condition and showed no appreciable changes over 60 min. The increase of turbidity in H2O was much slower than in D2O at the same salt concentration (3%). Lysozyme showed a critical concentration for nucleus formation whose value in H2O was lower than in D2O at 3% salt concentration. There are two different aggregation models, depending on the concentration of lysozyme. However, similar results were not obtained at 3% sodium ions in H2O. The initial aggregation rate was also dependent on the concentrations of both lysozyme and NaCI. Therefore, the effect of lysozyme concentration on the aggregation process in H2O may be smaller than in D2O.
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    Kinetics of Inhibition of Green Crab (Scylla Serrata) Alkaline Phosphatase by Sodium (2,2′-bipyridine) Oxodiperoxovanadate (1999)
    Springer
    The protein journal 18 (1999), S. 735-740 
    Details
    ISSN: 1573-4943
    Keywords: Alkaline phosphatase ; sodium (2, 2′-bipyridine) oxodiperoxovanadate ; inhibition ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Green crab (Scylla serrata) alkaline phosphatase (EC 3.1.3.1) is a metalloenzyme, which catalyzes the nonspecific hydrolysis of phosphate monoesters. The kinetics of inhibition of the enzyme by sodium (2, 2′-bipyridine) oxodiperoxovanadate, pV(bipy), has been studied. The time course of the hydrolysis of p-nitrophenyl-phosphate catalyzed by the enzyme in the presence of different pV(bipy) concentrations showed that at each pV(bipy) concentration, the rate decreased with increasing time until a straight line was approached, the straight line slopes are the same for all concentrations. The results suggest that the inhibition of the enzyme by pV(bipy) is a slow, reversible reaction with fractional remaining activity. The microscopic rate constants are determined for the reaction of inhibitor with the enzyme.
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    3D Monte Carlo Simulations of Diffusion Limited Cluster Aggregation up to the Sol-Gel Transition: Structure and Kinetics (1999)
    Springer
    Journal of sol gel science and technology 15 (1999), S. 129-136 
    Details
    ISSN: 1573-4846
    Keywords: simulation ; percolation ; aggregation ; structure ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Three-dimensional (3D) Monte Carlo simulations of diffusion limited cluster aggregation at different concentrations (φ) show a crossover from a flocculation regime at short times to a percolation regime close to the gel time (tg). Contrary to suggestions in the literature tg is independent of the system size (L) for large L. The structural and temporal crossovers between flocculation and percolation take place at characteristic values of the cluster mass (mc) and the time (tc) which depend on φ. After normalisation by these characteristic values the crossovers are independent of φ except for very small clusters and at short times. The concentration dependence of mc and tc indicates that the crossover takes place at a given cumulated volume fraction of the clusters independent of φ. At low concentrations the φ-dependence of tg is determined by the cluster growth in the flocculation regime.
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    Kinetics of Inhibition of Green Crab (Scylla serrata) Alkaline Phosphatase by L-Cysteine (1999)
    Springer
    The protein journal 18 (1999), S. 603-607 
    Details
    ISSN: 1573-4943
    Keywords: Alkaline phosphatase ; green crab ; inhibition ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The inhibition of alkaline phosphatase from green crab (Scylla serrata) by L-cysteine has been studied. The results show that L-cysteine gives a mixed-type inhibition. The progress-of-substrate-reaction method previously described by Tsou [(1988), Adv. Enzymol. Related Areas Mol. Biol. 61, 391–436] was used to study the inactivation kinetics of the enzyme by L-cysteine. The microscopic rate constants were determined for reaction of the inhibitor with the free enzyme and the enzyme–substrate complex (ES) The results show that inactivation of the enzyme by L-cysteine is a slow, reversible reaction. Comparison of the inactivation rate constants of free enzyme and ES suggests that the presence of the substrate offers marked protection of this enzyme against inactivation by L-cysteine.
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    ALASKA: A Mathematica package for two-state kinetic analysis of protein folding reactions (1998)
    Springer
    Journal of biomolecular NMR 11 (1998), S. 355-360 
    Details
    ISSN: 1573-5001
    Keywords: dynamic NMR ; kinetics ; line shape simulation ; protein folding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A Mathematica package (ALASKA) has been developed to simplify the measurement of protein folding kinetics by analysis of 1H NMR lineshape analysis. This package reads NMR data in ASCII format and can simulate an aromatic 1 NMR spectrum with or without lineshape broadening from chemical exchange. We describe the analysis of a urea denaturation series of a fast-folding protein, the G46A/G48A variant of monomeric λ repressor.
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    Monoclonal antibodies SMI 311 and SMI 312 as tools to investigate the maturation of nerve cells and axonal patterns in human fetal brain (1998)
    Springer
    Cell & tissue research 291 (1998), S. 433-443 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Neurofilaments ; Phosphorylation ; Differentiation ; Immunocytochemistry ; Brain storage ; Fixation ; Microwave ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Neurofilaments, which are exclusively found in nerve cells, are one of the earliest recognizable features of the maturing nervous system. The differential distribution of neurofilament proteins in varying degrees of phosphorylation within a neuron provides the possibility of selectively demonstrating either somata and dendrites or axons. Non-phosphorylated neurofilaments typical of somata and dendrites can be visualized with the aid of monoclonal antibody SMI 311, whereas antibody SMI 312 is directed against highly phosphorylated axonal epitopes of neurofilaments. The maturation of neuronal types, the development of area-specific axonal networks, and the gradients of maturation can thus be demonstrated. Optimal immunostaining with SMI 311 and SMI 312 is achieved when specimens are fixed in a mixture of paraformaldehyde and picric acid for up to 3 days and sections are incubated free-floating. Neurons, with their dendritic domains immunostained by SMI 311 in a Golgi-like manner, can be completely visualized in relatively thick sections. The limitations of Golgi-preparations, such as glia-labeling, artifacts, and the staining of only a small non-representative percentage of existing neurons, are not apparent in SMI preparations, which additionally provide the possibility of selectively staining axonal networks. The results achieved in normal fetal brain provide the basis for studies of developmental disturbances.
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    Alien plant species composition and associations with anthropogenic disturbance in North American forests (1998)
    Springer
    Plant ecology 139 (1998), S. 49-62 
    Details
    ISSN: 1573-5052
    Keywords: Alien species ; Anthropogenic disturbance ; Biological invasions ; Forests ; Ground vegetation ; United States
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A probability-based sampling scheme was used to survey plant species composition in forests of 16 states in seven geopolitical regions of the United States (California, Colorado, Minnesota, and parts of the Pacific Northwest, Southeast, Mid-Atlantic, and Northeast) in 1994. The proportion of alien species relative to the total species number and to canopy cover in the ground stratum (0–0.6 m height) was evaluated in 279 plots. Visually evident anthropogenic disturbances (e.g., artificial regeneration, logging, prescribed burning, and grazing by livestock), if any, were recorded on each plot. In each of the seven regions we quantified (1) the percentage of the number of species and total cover comprised of alien species, (2) the difference in these percentages for disturbed and undisturbed plots, and (3) the origin or native range for the alien species. The percentage of alien species ranged from approximately 4.5% (Colorado) to approximately 13.2% (California). The percentage of alien species cover ranged from approximately 1.5% in Colorado to 25% in California. In five regions, species introduced from temperate Eurasia comprised the largest proportion of alien species and cover. In the Southeast, species introduced from far eastern and subtropical Asia dominated the alien flora. In the Mid-Atlantic, the majority of alien species was Eurasian and the majority of alien species cover consisted of far eastern and subtropical Asian species. The proportion of plots in which at least one alien species was recorded was significantly higher in disturbed than undisturbed plots in the Southeast and marginally significantly higher ($p=0.053$) in the Northeast. These results are consistent with other published studies that indicate that anthropogenic disturbance affects the structure and composition of both the ground stratum and upper canopy of forest habitats. In other regions, however, no significant differences were found.
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    Kinetics of formation of GlcNAc-GlcNAc-P-P-dolichol by microsomes from the retina of the embryonic chick (1998)
    Springer
    Glycoconjugate journal 15 (1998), S. 11-17 
    Details
    ISSN: 1573-4986
    Keywords: dolichol pathway ; GlcNAc-P-P-dolichol ; GlcNAc-GlcNAc-P-P-dolichol ; kinetics ; retina ; GlcNAc-P-P-dolichol, N-acetylglucosaminylpyrophosphoryldolichol ; GlcNAc-GlcNAc-P-P-dolichol, N-acetyl-glucosaminyl-N-acetylglucosaminylpyrophosphoryldolichol ; TX-100, triton X-100 ; Tes, 2-{[tris-(hydroxymethyl)-methyl]-amino}-ethanesulfonic acid.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Little quantitative information is available concerning individual reactions of the dolichol pathway. We have investigated the kinetics of the GlcNAc-transferase that catalyzes the biosynthesis of GlcNAc-GlcNAc-P-P-dolichol using chemically synthesized GlcNAc-P-P-dolichol as the substrate. Using microsomal preparations from the retina of the embryonic chick as enzyme source, optimal incubation conditions of pH, metal ion and detergent concentrations were established, after which apparent kinetic constants (Km and Vmax) were determined under initial rate conditions for GlcNAc-P-P-dolichol and UDP-GlcNAc. These studies provide the first quantitative description of the kinetics of this reaction.
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    Stimulation as well as inhibition by antibiotics of the formation of GlcNAc-lipids of the dolichol pathway (1998)
    Springer
    Glycoconjugate journal 15 (1998), S. 405-414 
    Details
    ISSN: 1573-4986
    Keywords: dolichol pathway ; GlcNAc-P-P-dolichol ; GlcNAc-GlcNAc-P-P-dolichol ; antibiotics ; inhibition ; stimulation ; retina ; showdomycin ; diumycin ; amphomycin ; bacitracin ; microsomes ; embryonic chick ; kinetics ; Dionex ; GlcNAc-P-P-dolichol, N-acetylglucosaminylpyrophosphoryldolichol ; GlcNAc-GlcNAc-P-P-dolichol, N-acetyl-glucosaminyl-N-acetylglucosaminylpyrophosphoryldolichol ; TX-100, triton X-100 ; Tes, 2-{[tris-(hydroxy-methyl)-methyl]-amino}-ethanesulfonic acid ; chitobiose, GlcNAc-GlcNAc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The antiobiotics, diumycin, amphomycin, bacitracin, and showdomycin have been shown previously to block the synthesis of GlcNAc-P-P-dolichol and GlcNAc-GlcNAc-P-P-dolichol. In view of inconsistencies in the literature concerning the sites of inhibition, we have reinvestigated the influence of these drugs on the formation of these early intermediates of the dolichol pathway. Unexpectedly, when the individual products of the reactions were examined, instead of inhibition, showdomycin and bacitracin were found to stimulate the formation of GlcNAc-P-P-dolichol, and diumycin stimulated at low concentrations. Three derivatives of showdomycin were examined with similar results, showing stimulations of GlcNAc-P-P-dolichol formation of up to two-fold over controls. Amphomycin specifically inhibited GlcNAc-P-P-dolichol formation, an effect that was reversed by a high concentration of dolichyl phosphate. In contrast, with the exception of amphomycin, each compound directly inhibited the formation of GlcNAc-GlcNAc-P-P-dolichol. Using chemically synthesized GlcNAc-P-P-dolichol as substrate, the kinetics of inhibition of GlcNAc-GlcNAc-P-P-dolichol formation by showdomycin, bacitracin and diumycin was examined. The apparent Ki values calculated from these studies indicated that showdomycin was the most active inhibitor. These findings provide a new understanding of the action of these compounds on the GlcNAc-transferases of the dolichol pathway. © 1998 Rapid Science Ltd
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    Kinetic measurements of binding of galectin 3 to a laminin substratum (1999)
    Springer
    Glycoconjugate journal 16 (1999), S. 365-373 
    Details
    ISSN: 1573-4986
    Keywords: galectin 3 ; laminin binding ; kinetics ; cooperativity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Galectin 3, a β-galactoside binding protein, contains a C-terminal carbohydrate recognition domain (CRD) and an N-terminal segment including multiple repeats of a proline/tyrosine/glycine-rich motif. Previous work has shown that galectin 3 but not the isolated CRD binds to laminin, a multivalent ligand, with positive cooperativity indicating the formation of multiple interactions although the lectin in solution is monomeric. Using surface plasmon resonance, we find that hamster galectin 3 at sub-µmolar concentrations or its isolated CRD at all concentrations binds to a laminin substratum with similar association (kass; 10 – 30 000 M−1 S−1) and dissociation (kdiss; 0.2 – 0.3 S 1 −1 ) rates and weak affinity (Ka; 1 - 3 X 105 M−1). At higher concentrations of galectin 3 the off rate decreases ten fold leading to increased affinity. Ligation of an N-terminal epitope of galectin 3 with a monoclonal Fab fragment increases association and dissociation rates ten fold. A recombinant protein obtained by deletion of the first 93 N-terminal residues binds to laminin with positive cooperativity and a slowly dissociating fraction (Kdiss; 0.002 S−1) accummulates on the substratum. The data suggest that homophilic interactions between CRD as well as N terminal domains are implicated in galectin 3 aggregation on the substratum leading to positive binding cooperativity.
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    Folate Transport by Prawn Hepatopancreas Brush-Border Membrane Vesicles (1998)
    Springer
    Bioscience reports 18 (1998), S. 9-17 
    Details
    ISSN: 1573-4935
    Keywords: Folate transport ; prawn ; hepatopancreas ; brush-border membrane vesicles ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The transport system of folic acid (Pte-Glu) by brush-border membrane vesicles (BBMV) isolated from prawn (Penaeus japonicm) hepatopancreas, was studied by measuring the uptake of Pte-Glu. This uptake was found to have two components, intravesicular transport and membrane binding. Membrane binding was not affected by the presence of a transmembrane pH-gradient at a short incubation period. However, a transmembrane pH-gradient increased membrane binding at 60 min. The transport of Pte-Glu appeared to be carrier-mediated, was stimulated by an inwardly proton gradient (pH 5.5 outside, 7.4 inside) and was unaffected by a sodium-gradient. The relationship between pH gradient-driven Pte-Glu uptake and medium Pte-Glu concentration followed saturating Michaelis–Menten kinetics. Eadie–Hofstee representation of the pH gradient-driven Pte-Glu uptake indicated a single transport system with a Km of 0.37 μM and Vmax of 1.06 pmol/mg protein/15 s. These findings indicate that BBMV isolated from prawn hepatopancreas possesses a Pte-Glu transport system similar to that described in mammalian intestine.
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    The photosystem II subunit CP29 can be phosphorylated in both C3 and C4 plants as suggested by sequence analysis (1998)
    Springer
    Plant molecular biology 36 (1998), S. 11-22 
    Details
    ISSN: 1573-5028
    Keywords: chlorophyll a/b protein ; CP29 ; Phosphorylation ; Photosystem II ; cold stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The CP29 subunit of Photosystem II is reversibly phosphorylated in Zea mays upon exposure to high light in the cold (Bergantino et al., J Biol Chem 270 (1995) 8474–8481). This phenomenon was previously proposed to be restricted to C4 plants. We present the complete sequence of the CP29 protein, deduced from a maize Lhcb4 cDNA clone, and its comparison with the previously known Lhcb4 sequences of two C3 plants: Hordeum vulgare and Arabidopsis thaliana. Despite the relatively low degree of homology in their amino-terminal region, i.e. the part of the molecule which is phosphorylated in maize, the three polypeptides conserve consensus sequences for the site of phosphorylation. We proved by immunoblotting and 33P-labelling that the same post-translational modification occurs in barley. Being thus common to C3 and C4 plant species, the phosphorylation of this minor antenna complex of Photosystem II appears now as a widespread phenomenon, possibly part of the phosphorylation cascade which signals the redox status of the plastoquinone to the nuclear transcription apparatus. Arabidopsis plants do not show phosphorylation of CP29 in the same conditions, but other low-molecular-weight phosphoproteins, whose role need to be elucidated, become evident.
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    Low temperature-stimulated phosphorylation regulates the binding of nuclear factors to the promoter of Wcs120, a cold-specific gene in wheat (1998)
    Springer
    Molecular genetics and genomics 257 (1998), S. 157-166 
    Details
    ISSN: 1617-4623
    Keywords: Key words Cold ; Phosphorylation ; Promoter ; Transcription ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Wcs120 gene encodes a highly abundant protein which appears to play an important role during cold acclimation of wheat. To understand the regulatory mechanism controlling its expression at low temperature, the promoter region has been characterized. Electrophoretic mobility shift assays using short promoter fragments revealed the presence in nuclear extracts from non-acclimated (NA) plants of multiple DNA-binding proteins which interact with several elements. In contrast, no DNA-binding activity was observed in the nuclear extracts from cold-acclimated (CA) plants. In vitro dephosphorylation of these CA nuclear extracts with alkaline phosphatase restored the binding activity. Moreover, okadaic acid (a potent phosphatase inhibitor) markedly stimulated the in vivo accumulation of the WCS120 family of proteins. This suggests that protein phosphatases PP1 and/or PP2A negatively regulate the expression of the Wcs120 gene. In addition, both Ca2+-dependent and Ca2+-independent kinase activities were found to be significantly higher in the CA nuclear extracts. Western analysis using antibodies directed against protein kinase C (PKC) isoforms showed that a PKCγ homolog (84 kDa) is selectively translocated into the nucleus in response to low temperature. Taken together, our results suggest that, in vivo, the expression of the Wcs120 gene may be regulated by nuclear factors whose binding activity is modulated by a phosphorylation/dephosphorylation mechanism.
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    URL: http://dx.doi.org/10.1007/s004380050635
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    Time-resolved electron transfer at the donor side of Rhodopseudomonas viridis photosynthetic reaction centers in whole cells (1998)
    Springer
    Photosynthesis research 55 (1998), S. 317-323 
    Details
    ISSN: 1573-5079
    Keywords: bound cytochrome ; electron transfer ; kinetics ; Rhodopseudomonas viridis ; thermodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have studied the electron transfer reactions from the tetraheme cytochrome of Rhodopseudomonas viridis to the oxidized primary donor in whole cells with a new high sensitivity spectrophotometer. In this apparatus the monochromatic detecting flashes are provided by a YAG pumped Optical Parametric Oscillator, allowing a 10 ns time resolution. When four hemes are reduced the observed electron transfer reaction sequence is the following: first the low-potential c552 heme (the number refers to the maximum absorption wavelength in the alpha-band region) is oxidized with a half time of 130 ns, in agreement with previous reports of measurements performed with purified reaction centers. Then, the electron hole is transferred to the low potential c554 heme with a half time of 2.6 µs. When only the two high potential hemes are reduced the observed electron transfer sequence is the following: oxidation of the high potential c559 heme in the hundreds of ns time range (410 ns), reduction of this heme by the high potential c556 heme in the µs time range (2.7 µs). This confirms the first steps of electron transfer observed in isolated reaction centers. However, in the microsecond time domain, the overall amount of oxidized hemes increases suggesting that, in vivo, the equilibrium constant between the P+/P and the c559ox/c559red couples is significantly lower than expected from the difference in their midpoint potentials.
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    Characterization of the heat shock protein response of Atlantic salmon (Salmo salar) (1999)
    Springer
    Fish physiology and biochemistry 20 (1999), S. 279-292 
    Details
    ISSN: 1573-5168
    Keywords: heat shock proteins ; hsp70 ; kinetics ; in vitro ; salmon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The heat shock protein (hsp) response of juvenile Atlantic salmon, Salmo salar was investigated in isolated tissues subjected to various degrees of thermal shock. Distinct but overlapping arrays of proteins from the major hsp families (hsps 100, 90, 70, 60 and small hsps) were induced in branchial lamellae, hepatic tissue and erythrocytes. The two most prominent proteins induced by heat shock (MW ≅ 65 and 66 kDa) were found to be antigenic homologues of mammalian hsps72/73. A 2.6 kb transcript upregulated by the same conditions hybridized with cDNA probes to both human and salmon hsp70. Branchial lamellae exhibited the greatest degree of thermotolerance and mounted the most significant heat shock response. Moderate thermal shock induced more species of proteins in branchial lamellae than in hepatic tissue or erythrocytes, with the rate of hsp65/66 synthesis increased by as much as five fold. Thermal shock induced hsp65/66 eight fold in erythrocytes. In contrast, hepatic tissue which was least tolerant of thermal shock, lacked the inducible hsp65 and exhibited minimal induction of hsp66. Persistence of hsps was tested in erythrocytes, where elevated levels remained in the cells for at least 48 h after heat shock. The temporal pattern and magnitude of the hsp response in the stenothermal Atlantic salmon differed from that previously reported for eurythermal species. Also notable was the limited hsp response mounted by salmon tissues exposed to sodium arsenite, a known inducer of hsps. The characteristics of the hsp response to thermal shock support the significance of these proteins in adaptation of Atlantic salmon to environmental insult.
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    Kinetics of the Reconstituted Tricarboxylate Carrier from Eel Liver Mitochondria (1998)
    Springer
    Journal of bioenergetics and biomembranes 30 (1998), S. 555-563 
    Details
    ISSN: 1573-6881
    Keywords: Tricarboxylate carrier ; mitochondria ; transport ; liposomes ; kinetics ; reconstitution ; eel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The tricarboxylate carrier from eel liver mitochondria was purified by chromatography on hydroxyapatite and Matrix Gel Blue B and reconstituted into liposomes by removal of the detergent with Amberlite. Optimal transport activity was obtained by using a phospholipid concentration of 11.5 mg/ml, a Triton X-114/phospholipid ratio of 0.9, and ten passages through the same Amberlite column. The activity of the carrier was influenced by the phospholipid composition of the liposomes, being increased by cardiolipin and phosphatidylethanolamine and decreased by phosphatidylinositol. The reconstituted tricarboxylate carrier catalyzed a first-order reaction of citrate/citrate or citrate/malate exchange. The maximum transport rate of external [14C]citrate was 9.0 mmol/min per g of tricarboxylate carrier protein at 25°C and this value was virtually independent of the type of substrate present in the external or internal space of the liposomes. The half-saturation constant (K m) was 62 μM for citrate and 541 μM for malate. The activation energy of the citrate/citrate exchange reaction was 74 kJ/mol from 5 to 19°C and 31 kJ/mol from 19 to 35°C. The rate of the exchange had an external pH optimum of 8.
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    Structure function relationship of vanadate bound to a single site in chloroplast CF1-ATPase as determined by X-ray absorption (1998)
    Springer
    Photosynthesis research 57 (1998), S. 275-285 
    Details
    ISSN: 1573-5079
    Keywords: ATP synthase ; EXAFS ; k-edge ; kinetics ; MgADP ; transition state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The structure of vanadate, a phosphate analogue which was suggested to function in the presence of tightly bound ADP and divalent cations as a transition state inhibitor of CF1-ATPase, was investigated by X-ray absorption spectroscopy. Analysis of the vanadium K-edge was used for determination of the structure of vanadate bound to a single site in CF1-ATPase containing a single tightly bound ADP. There was a decrease in the intensity of the 1s-3d pre-edge transition and a change in the shape of two other shoulders at the edge region upon binding of vanadate to CF1 in the presence of Mg2+ ions. The changes are due to alteration in the structure of vanadium from tetrahedral to a five-coordinated trigonal bipyramidal geometry. Comparison of the pre-edge peak intensity of ADP-vanadate complex, and model compound resolved by crystallography support the proposed structure of CF1-bound vanadate. 51V NMR measurements were used to verify the pentacoordinated structure of ADP-vanadate complex used as a model in the X-ray absorption studies. The inhibition of a single and multiple site activity by vanadate and by MgADP was measured. Vanadate inhibition of CF1-ATPase activity decreased more than 90 fold in the presence of MgADP. A differential specificity of the inhibition in single and multiple mode of activity was observed. It is suggested that ADP-vanadate binds to the active sites of the enzyme as a pentacoordinated vanadium having approximate trigonal bipyramidal geometry. This structure is analogous to the proposed transition state of the phosphate during the synthesis and the hydrolysis of ATP by CF1.
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    Peroxy Radical Kinetics Resulting from the OH-Initiated Oxidation of 1,3-Butadiene, 2,3-Dimethyl-1,3-Butadiene and Isoprene (1998)
    Springer
    Journal of atmospheric chemistry 29 (1998), S. 267-298 
    Details
    ISSN: 1573-0662
    Keywords: peroxy radicals ; kinetics ; conjugateddienes ; biogenic VOC ; degradation mechanisms ; tropospheric ozone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The laser flash photolysis/UV absorption spectrometry technique has been used to investigate the kinetics of the peroxy radical permutation reactions (i.e. self and cross reactions) arising from the OH-initiated oxidation of isoprene (2-methyl-1,3-butadiene), and of the simpler, but related conjugated dienes, 1,3-butadiene and 2,3-dimethyl-1,3-butadiene. The results of the two simpler systems are analysed to provide values of the rate coefficients for the 6 peroxy radical permutation reactions of the three types of isomeric peroxy radical produced in each system (T = 298 K, P = 760 Torr). The rate coefficients are all significantly larger than values estimated previously by extrapolation of structure-reactivity relationships based on the kinetics of a limited dataset of simpler radicals containing similar structural features. The results are discussed in terms of trends in self and cross reaction reactivity of primary, secondary and tertiary peroxy radicals containing combinations of allyl, β-hydroxy and δ-hydroxy functionalities. Since the peroxy radicals formed in these systems are structurally very similar to those formed in the isoprene system, the kinetic parameters derived from the results of the simpler systems are used to assist the assignment of kinetic parameters to the 21 permutation reactions of the six types of isomeric peroxy radical generated in the isoprene system. Kinetic models describing the OH-initiated degradation of all three conjugated dienes to first generation products in the absence of NOx are recommended, which are also consistent with available end product studies. The model for isoprene is considered to be a further improvement on that suggested previously for its OH-initiated oxidation in the absence of NOx. The mechanism is further extended to include chemistry applicable to ‘NOx-present’ conditions, and calculated product yields are compared with those reported in the literature.
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    Kinetics of the Gas-Phase Reactions of OH and NO3 Radicals and O3 with the Monoterpene Reaction Products Pinonaldehyde, Caronaldehyde, and Sabinaketone (1998)
    Springer
    Journal of atmospheric chemistry 31 (1998), S. 281-297 
    Details
    ISSN: 1573-0662
    Keywords: hydroxyl radical ; nitrate radical ; ozone ; pinonaldehyde ; caronaldehyde ; sabinaketone ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Using a relative rate method, rate constants have been measured for the gas-phase reactions of OH and NO3 radicals with pinonaldehyde, caronaldehyde and sabinaketone at 296 ± 2 K. The OH radical reaction rate constants obtained are (in units of 10−12 cm3 molecule−1 s−1): pinonaldehyde, 48 ± 8; caronaldehyde, 48 ± 8; and sabinaketone, 5.1 ± 1.4, and the NO3 radical reaction rate constants are (in units of 10−14 cm3 molecule−1 s−1): pinonaldehyde, 2.0 ± 0.9; caronaldehyde, 2.5 ± 1.1; and sabinaketone, 0.036 ± 0.023, where the error limits include the estimated overall uncertainties in the rate constants for the reference compounds. Upper limits to the O3 reaction rate constants were also obtained, of 〈2 × 10−20 cm3 molecule−1 s−1 for pinonaldehyde and caronaldehyde, and 〈5 × 10−20 cm3 molecule−1 s−1 for sabinaketone. These reaction rate constants are combined with estimated ambient tropospheric concentrations of OH radicals, NO3 radicals and O3 to calculate tropospheric lifetimes and dominant transformation process(es) of these and other monoterpene reaction products.
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    Absolute Rate Coefficients for the Gas-Phase Reactions of NO3 Radical with a Series of Monoterpenes at T = 298 to 433 K (1999)
    Springer
    Journal of atmospheric chemistry 33 (1999), S. 265-282 
    Details
    ISSN: 1573-0662
    Keywords: atmosphere ; kinetics ; nitrate radical ; monoterpenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The aim of this work is to study the reactivity of some naturally emitted terpenes, 2-carene, sabinene, myrcene, α-phellandrene, d-limonene, terpinolene and γ-terpinene, towards NO3 radical to evaluate the importance of these reactions in the atmosphere and their atmospheric impact. The experiments with these monoterpenes have been carried out under second-order kinetic conditions over the range of temperature 298–433 K, using a discharge flow system and monitoring the NO3 radical by Laser Induced Fluorescence (LIF). This work is the first temperature dependence study for the reactions of the nitrate radical with the above-mentioned monoterpenes. The measured rate constants at 298 K for the reaction of NO3 with such terpenes are as follows: 2-carene, 16.6 ± 1.8, sabinene 10.7 ± 1.6, myrcene 12.8 ± 1.1, α-phellandrene 42 ± 10, d-limonene 9.4 ± 0.9, terpinolene 52 ± 9 and γ-terpinene 24 ± 7, in units of 10-12 cm3 molecule-1 s-1. The proposed Arrhenius expressions, for the reactions of NO3 with 2-carene, sabinene, myrcene and α-phellandrene are, respectively k1 = (1.4 ± 0.7) × 10-12 exp[(741 ± 190/T)] (cm3 molecule-1 s-1), k2=(2.3 ± 1.3) × 10-10 exp[−(940 ± 200/T)] (cm3 molecule-1 s-1), k3 = (2.2 ± 0.2) × 10-12 exp[(523 ± 35/T)] (cm3 molecule1 s-1) and k4 = (1.9 ± 1.3) × 10-9 exp[−(1158 ± 270/T)] (cm3 molecule-1 s-1). A decrease in the rate constants when raising the temperature has also been found for the reaction of d-limonene with NO3 while an increase in the rate constant with temperature has been observed for the reactions of terpinolene and γ-terpinene with NO3. Tropospheric half-lives for these terpenes have been calculated at night and during the day for typical NO3 and OH concentrations showing that both radicals provide an effective tropospheric sink for these compounds and that the night-time reaction with NO3 radical can be an important, if not dominant, loss process for these naturally emitted organics and for NO3 radicals.
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    URL: http://dx.doi.org/10.1023/A:1006178530211
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    Laboratory Kinetic Studies of the Reactions of Cl Atoms with Species of Biogenic Origin: δ3-Carene, Isoprene, Methacrolein and Methyl Vinyl Ketone (1999)
    Springer
    Journal of atmospheric chemistry 34 (1999), S. 163-170 
    Details
    ISSN: 1573-0662
    Keywords: δ3-carene ; chlorine atoms ; isoprene ; kinetics ; methacrolein and methyl vinyl ketone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The rate coefficients for the reaction between atomic chlorine and a number of naturally occurring species have been measured at ambient temperature and atmospheric pressure using the relative rate technique. The values obtained were (4.0 ± 0.8) × 10-10, (2.1 ± 0.5) × 10-10, (3.2 ± 0.5) × 10-10, and (4.9 ± 0.5) × 10-10 cm3 molecule-1 s-1, for reactions with isoprene, methyl vinyl ketone, methacrolein and δ3-carene, respectively. The value obtained for isoprene compares favourably with previously reported values. No values have been reported to date for the rate constants of the other reactions.
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    Energetic Approach to Kinetics of Mechanochemical Process (1998)
    Springer
    Journal of thermal analysis and calorimetry 52 (1998), S. 463-473 
    Details
    ISSN: 1572-8943
    Keywords: energetic efficiency ; intensity of treatment ; kinetics ; mechanochemical process
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Kinetics of a mechanochemical process is proposed to describe quantitatively with a problem set-up scaled to energy instead of time. This makes possible the comparability of experimental data obtained in machines with different intensities of treatment.
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    URL: http://dx.doi.org/10.1023/A:1010130530563
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    Non-isothermal Decomposition Kinetics of Complex of Co(III), Ni(II) with O,O'-dialkyldithiophosphates and Adducts of Ni-complex with Pyridines (1999)
    Springer
    Journal of thermal analysis and calorimetry 55 (1999), S. 197-203 
    Details
    ISSN: 1572-8943
    Keywords: adducts ; cobalt complex ; DSC ; kinetics ; nickel complex ; O,O'-dialkyldithiophosphate ; pyridine ; TG-DTG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermal behaviour of tri(O,O'-diisopropyldithiophosphate)cobalt(III), Co(dptp)3 and bis (O,O'-diethyldithiophosphate)nickel(II), Ni(detp)2 and its adducts with pyridine, Ni(detp)2(py)2 or 4-methylpyridine, Ni(detp)(mpy)2 in a dynamic nitrogen atmosphere was investigated by TG-DTG and DSC techniques, which showed a medium endothermic peak for the evolution process of pyridine(or 4-methylpyridine) and a strong exothermic peak for that of O,O'-diethyldithiophosphate. The thermal stability and decomposition patterns for these compounds were compared and interpreted in terms of structural features such as bond character and steric effects. The kinetic parameters and mechanisms of every decomposition stage involved for all these complexes were obtained employing the non-isothermal kinetic analysis method suggested by Malek et al., which showed the kinetics mechanism for pyrolysis of pyridine(or 4-methylpyridine) is an S-B empirical model with lower activation energy, while that of O,O'-dialkyldithiophosphate is a diffusion model. These results are in accord with the fact that two ligands are of different type.
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