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  • 1
    Electronic Resource
    Electronic Resource
    Invariant kinetic approach to the description of a rock fracture process and induced seismic events (1996)
    Springer
    Pure and applied geophysics 147 (1996), S. 367-375 
    Details
    ISSN: 1420-9136
    Keywords: Induced seismicity ; kinetics ; rock fracture ; rockburst ; earthquake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Powerful seismic events, such as earthquakes and rockbursts, are caused by the accumulation of energy in rocks and loss of rock mass stability. Usually methods of their forecasting are based on the registration of anomalous behavior of geophysical fields. However an efficiency of this approach is low. The present paper proposes a kinetic approach to the description of rock fracture process, which can be used for the forecasting of seismic events and an investigation of structure and energy distributions in rock. 3-D and 1-D kinetic equations describing a process of cluster formation in rock were obtained. The equations are invariant to deformation conditions and to the scale level of events. They showed a good agreement with the results of field observations and laboratory experiments. It was also shown that these equations well describe the processes of earthquake, rockburst and rock sample failure preparation. Catalogues of rockbursts in mines were analyzed with the use of the kinetic equations to find out evidence of induced seismic events. The proposed approach makes it possible to reveal trends in rock behavior and thus predict the rock failure at different scale levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00877489
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of pyrophosphate and orotidine monophosphate on cytosine deaminase regulatory properties (1985)
    Springer
    Cellular and molecular life sciences 41 (1985), S. 1563-1564 
    Details
    ISSN: 1420-9071
    Keywords: Cytosine deaminase ; kinetics ; pyrophosphate ; orotidine monophosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The maximal velocity of the reaction (Vmax) and the half-saturation constant (K0.5) values of theS. typhimurium cytosine deaminase were altered in the presence of its effectors, pyrophosphate and orotidine monophosphate. From the kinetics of orotidine monophosphate inhibition of cytosine deaminase, it was characterized as a mixed-type noncompetitive inhibitor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01964808
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  • 3
    Electronic Resource
    Electronic Resource
    A comparison of pyridoxal 5′-phosphate dependent decarboxylase and transaminase enzymes at a molecular level (1991)
    Springer
    Cellular and molecular life sciences 47 (1991), S. 1104-1118 
    Details
    ISSN: 1420-9071
    Keywords: Transaminase ; decarboxylase ; serine hydroxymethyltransferase ; pyridoxal 5′-phosphate ; enzyme mechanism ; stereochemistry ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Pyridoxal 5′-phosphate is a coenzyme for a number of enzymes which catalyse reactions at Cα of amino acid substrates including transaminases, decarboxylases and serine hydroxymethyltransferase. Using the X-ray coordinates for a transaminase, aspartate aminotransferase, and the results of stereochemical and mechanistic studies for decarboxylases and serine hydroxymethyltransferase, an active-site structure for the decarboxylase group is constructed. The structure of the active-site is further refined through active-site pyridoxyllysine peptide sequence comparison and a 3-D catalytic mechanism for the L-α-amino acid decarboxylases is proposed. The chemistry of serine hydroxymethyltransferase is re-examined in the light of the proposed decarboxylase mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01918374
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  • 4
    Electronic Resource
    Electronic Resource
    Kinetics of sodiumd-glucose cotransport in bovine intestinal brush border vesicles (1984)
    Springer
    The journal of membrane biology 79 (1984), S. 41-51 
    Details
    ISSN: 1432-1424
    Keywords: glucose ; brush borders ; sodium cotransport ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Brush border membrane vesicles (BBMV) purified from steer jejunum were used to study the kinetics of sodiumd-glucose cotransport under voltage clamped, zero-trans conditions. When the initial rate of glucose transport (J gluc) was measured over a wide range of glucose concentrations ([S]=0.01–20mm), curvature of the Woolf-Augustinsson-Hofstee plots was seen, compatible with a diffusional and one major, high capacity (maximal transport rateJ max=5.8–8.8 nmol/mg·min) saturable system. Further studies indicated that changes incis [Na] altered theK t , but not theJ max, suggesting the presence of a rapid-equilibrium, ordered bireactant system with sodium adding first.Trans sodium inhibitedJ gluc hyperbolically. KCl-valinomycin diffusion potentials, inner membrane face positive, loweredJ gluc, while potentials of the opposite polarity raiseJ gluc. At low glucose concentrations ([S]〈0.05mm), a second, minor, high affinity transport system was indicated. Further evidence for this second saturable system was provided by sodium activation curves, which were hyperbolic when [S]=0.5mm, but were sigmoidal when [S]=.0.01mm. Simultaneous fluxes of22Na and [3H]glucose at 1mm glucose and 30mm NaCl yielded a cotransport-dependent flux ratio of 2∶1 sodium/glucose, suggestive of 1∶1 (Na/glucose) high capacity, low affinity system and a ∼3∶1 (Na/glucose) high affinity, low capacity system. Kinetic experiments with rabbit jejunal brush borders revealed two major Na-dependent saturable systems. Extravesicular (cis) Na changed theK t , but not theJ max of the major system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01868525
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  • 5
    Electronic Resource
    Electronic Resource
    Characterization of ion channels from Acetabularia plasma membrane in planar lipid bilayers (1993)
    Springer
    The journal of membrane biology 133 (1993), S. 145-160 
    Details
    ISSN: 1432-1424
    Keywords: Acetabularia ; K+ channels ; kinetics ; planar lipid bilayers ; voltage dependence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Plasma membrane from Acetabularia acetabulum was prepared by aqueous-polymer two-phase partitioning and incorporated into planar 1-palmitoyl-2-oleoyl phosphatidylethanolamine bilayers by stirring in the presence of a (cis∶trans) 325∶100 mm KCl gradient. Under these conditions five distinct K+-selective channels were observed which had unitary chord-conductances (determined between 30 mV either side of the reversal potential) and frequencies of incorporation (in parentheses) of 1,600 pS (26%), 485 pS (21%), 259 pS (53%), 140 pS (37%) and 27 pS (37%). Two Cl−-selective channels were also observed, which had unitary chord-conductances of 8 and 48 pS and were present in 21 and 16% of bilayers, respectively. The voltage dependencies of channel open probability (P o ), open-state time constant (τ o) and closed-state time constant (τ c) were determined for the 259, 140 and 27 pS K+ channels. The P o of all three channels increased with increasingly positive membrane potentials. Thus, since these channels were oriented with their extracellular face adjacent to the cis chamber, which was grounded, all would exhibit outward rectification in vivo. Changes in P o were effected by modulation of τ c in all channels, which shortened as membrane potentials became more positive, and also of τ o in the 140 and 27pS channels, which increased as membrane potentials became more positive. Extracellular (cis) KCl concentration (and/or the KCl gradient across the bilayer) affected the P o of all three K+ channels, shifting the P o /membrane potential relationship in the direction of the change in the potassium reversal potential. In all channels this was achieved largely by changes in τ c .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233795
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  • 6
    Electronic Resource
    Electronic Resource
    Protonophore anion permeability of the human red cell membrane determined in the presence of valinomycin (1988)
    Springer
    The journal of membrane biology 102 (1988), S. 225-234 
    Details
    ISSN: 1432-1424
    Keywords: erythrocytes ; valinomycin ; protonophore ; CCCP ; permeability ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary A transport model for translocation of the protonophore CCCP across the red cell membrane has been established and cellular CCCP binding parameters have been determined. The time course of the CCCP redistribution across the red cell membrane, following a jump in membrane potential induced by valinomycin addition, has been characterized by fitting values of preequilibrium extracellular pHvs. time to the transport model. It is demonstrated, that even in the presence of valinomycin, the CCCP-anion is “well behaved,” in that the translocation can be described by simple electrodiffusion. The translocation kinetics conform to an Eyring transport model, with a single activation energy barrier, contrary to translocation across lipid bilayers, that is reported to follow a transport model with a plateau in the activation energy barrier. The CCCP anion permeability across the red cell membrane has been calculated to be close to 2.0×10−4 cm/sec at 37°C with small variations between donors. Thus the permeability of CCCP in the human red cell membrane deviates from that found in black lipid membranes, in which the permeability is found to be a factor of 10 higher.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01925716
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  • 7
    Electronic Resource
    Electronic Resource
    Na+, Li+ and Cl− transport by brush border membranes from rabbit jejunum (1983)
    Springer
    The journal of membrane biology 74 (1983), S. 85-94 
    Details
    ISSN: 1432-1424
    Keywords: sodium ; lithium ; chloride ; pH ; transport ; kinetics ; ion permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Na+, Li+, K+, Rb+, Br−, Cl− and SO 4 2− transport were studied in brush border membrane vesicles isolated from rabbit jejunum., Li+ uptakes were measured by flameless atomic absorption spectroscopy, and all others were measured using isotopic flux and liquid scintillation counting. All uptakes were performed with a rapid filtration procedure. A method is presented for separating various components of ion uptake: 1) passive diffusion, 2) mediated transport and 3) binding. It was concluded that a Na+/H+ exchange mechanism exists in the jejunal brush border. The exchanger was inhibited with 300 μm amiloride or harmaline. The kinetic parameters for sodium transport by this mechanism depend on the pH of the intravesicular solution. The application of a pH gradient (pHin=5.5, pHout=7.5) causes an increase inJ max (50 to 125 pmol/mg protein·sec) with no change inK t (≈4.5mm). Competition experiments show that other monovalent cations, e.g. Li+ and NH 4 + , share the Na+/H+ exchanger. This was confirmed with direct measurements of Li+ uptakes. Saturable uptake mechanisms were also observed for K+, Rb+ and SO 4 2− , but not for Br−. TheJ max for K+ and Rb+ are similar to theJ max for Na+, suggesting that they may share a transporter. The SO 4 2− system appears to be a Na+/SO 4 2− cotransport system. There does not appear to be either a Cl−/OH− transport mechanism of the type observed in ileum or a specific Na+/Cl− symporter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870497
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  • 8
    Electronic Resource
    Electronic Resource
    The kinetics of transport inhibition by noncompetitive inhibitors (1983)
    Springer
    The journal of membrane biology 74 (1983), S. 175-182 
    Details
    ISSN: 1432-1424
    Keywords: kinetics ; transport inhibition ; noncompetitive ; competitive ; inhibition mechanism ; carrier model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary A new analysis of the conventional carrier model shows that noncompetitive inhibitors can give rise to either competitive, noncompetitive or uncompetitive kinetics; the true mechanism and also the relative affinity of the inhibitor on each surface of the membrane can be decided from the patterns of inhibition observed in different transport experiments. The priciples governing the kinetics of inhibition apply to both reversible and irreversible inhibitors, for in either case the substrate may increase or decrease inhibition or be without effect. Ambiguity arises if the noncompetitive inhibitor acts on only one side of the membrane and if the substrate, in the course of being transported, alters the steady-state distribution of the carrier between inner and outer forms. In facilitated transport systems only equilibrium exchange should give rise to noncompetitive kinetics, whatever the location of the inhibitor. In active systems even the interpretation of exchange in the final steadystate is complicated if the energy-coupling mechanism produces a large displacement in the distribution of the free carrier or the substrate complex: the inhibition could be competitive or uncompetitive, depending on the location of the inhibitor. The actual mechanism is revealed in the uncoupled system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02332121
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  • 9
    Electronic Resource
    Electronic Resource
    Generalized kinetic analysis of ion-driven cotransport systems: II. Random ligand binding as a simple explanation for non-Michaelian kinetics (1986)
    Springer
    The journal of membrane biology 90 (1986), S. 67-87 
    Details
    ISSN: 1432-1424
    Keywords: cotransport ; kinetics ; reaction kinetic model ; dual isotherm ; random binding ; slip
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Solute uptake in many cells is characterized by a series of additive Michaelis-Menten functions. Several explanations for these kinetics have been advanced: unstirred layers, transport across more than one membrane, effects of solute concentration on membrane potential, numerous carrier systems. Although each of these explanations might suffice for individual cases, none provides a comprehensive basis for interpretation of the kinetics. The most common mechanism of solute absorption involves cotransport of solute with a driver ion. A model is developed in which solute and driver ion bind randomly to a membrane-bound carrier which provides a single transmembrane pathway for transport. The kinetic properties of the model are explored with particular reference to its capacity to generate additive Michaelian functions for initial rate measurements of isotopic solute influx. In accord with previous analysis of ordered binding models (Sanders, D., Hansen, U.-P., Gradmann, D., Slayman, C.L. (1984)J. Membrane Biol. 77:123), the conventional assumption that transmembrane transit rate-limits transport has not been applied. Random binding carriers can exhibit single or multiple Michaelian kinetics in response to changing substrate concentration. These kinetics include high affinity/low velocity and low affinity/high velocity phases (so-called “dual isotherms”) which are commonly observed in plant cells. Other combinations of the Michaelis parameters can result incis-(substrate) inhibition. Despite the generality of the random binding scheme and the complexity of the underlying rate equation, a number of predictive and testable features emerge. If external driver ion concentration is saturating, single Michaelian functions always result and increasing internal substrate concentration causes uncompetitive inhibition of transport. Numerical analysis of the model in conditions thought to resemble those in many experiments demonstrates that small relative differences in a few key component rate constants of the carrier reaction cycle are instrumental in generation of dual isotherms. The random binding model makes the important prediction that the contributions of the two isotherms show opposing dependence on external concentration of driver ion as this approaches saturation. In the one case in which this dependence has been examined experimentally, the model provides a good description of the data. Charge translocation characteristics of the carrier can be determined from steady-state kinetic data on the basis of the response of substrate flux to modulation of internal driver ion concentration. The application of the model to dual isotherm kinetics is discussed in relation to “slip” models of cotransport, in which the carrier is assumed to have the capability to transport substrate alone or with the driver ion. A method for distinguishing between the two models is suggested on the basis of measurement of charge/solute transport stoichiometry as a function of external driver ion concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01869687
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  • 10
    Electronic Resource
    Electronic Resource
    Initial steps of αand β-d-glucose binding to intact red cell membrane (1993)
    Springer
    The journal of membrane biology 132 (1993), S. 167-178 
    Details
    ISSN: 1432-1424
    Keywords: red cell ; glucose transport protein ; GLUT1 ; kinetics ; rapid reactions ; tryptophan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The kinetics of the initial phases of d-glucose binding to the glucose transport protein (GLUT1) of the human red cell can be followed by stopped-flow measurements of the time course of tryptophan (trp) fluorescence enhancement. A number of control experiments have shown that the trp fluorescence kinetics are the result of conformational changes in GLUT1. One shows that nontransportable l-glucose has no kinetic response, in contrast to d-glucose kinetics. Other controls show that d-glucose binding is inhibited by cytochalasin B and by extracellular d-maltose. A typical time course for a transportable sugar, such as d-glucose, consists of a zero-time displacement, too fast for us to measure, followed by three rapid reactions whose exponential time courses have rate constants of0.5–100 sec+−1 at 20°C. It is suggested that the zero-time displacement represents the initial bimolecular ligand/GLUT1 association. Exponential 1 appears to be located at, or near, the external membrane face where it is involved in discriminating among the sugars. Exponential 3 is apparently controlled by events at the cytosolic face. Trp kinetics distinguish the K d of the epimer, d-galactose, from the K dfor d-glucose, with results in agreement with determinations by other methods. Trp kinetics distinguish between the binding of the α- and β-d-glucose anomers. The exponential 1 activation energy of the β-anomer, 13.6 ± 1.4 kcal mol+−1, is less than that of α-d-glucose, 18.4 ± 0.8 kcal mol+−1, and the two Arrhenius lines cross at ≈23.5°C. The temperature dependence of the kinetic response following α-d-glucose binding illustrates the interplay among the exponentials and the increasing dominance of exponential 2 as the temperature increases from 22.3 to 36.6°C. The existence of these interrelations means that previously acceptable approximations in simplified reaction schemes for sugar transport will now have to be justified on a point-to-point basis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239006
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  • 11
    Electronic Resource
    Electronic Resource
    Characteristics of manganese current and its comparison with currents carried by other divalent cations in snail soma membranes (1983)
    Springer
    The journal of membrane biology 76 (1983), S. 289-297 
    Details
    ISSN: 1432-1424
    Keywords: neuron ; internal perfusion ; Mn current ; kinetics ; Ca blocker
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Characteristics of currents carried by Mn2+ and other divalent cations were studied in the isolated identified neuron in the circumesophageal ganglia ofHelix aspersa using a suction pipette technique which allows internal perfusion of the cell body and voltage clamp. Increases in [Mn2+] 0 induced not only saturation of the peak ofI Mn but also shifts theI–V relationships along the voltage axis to the more positive potentials. Internal perfusion with F−, which blocks Ca channels, depressedI Mn. Diltiazem, an organic Ca blocker, inhibitedI Mn over the entire range of theI–V relation without shifting the threshold and peak voltage of theI–V relation. Co2+, Ni2+, Cd2+ and La3+ also suppressedI Mn. Relative maximum peak currents of the divalent cations wereI Ba=I Sr〉I Ca〉I Mn=I Zn. Time constants for activation (τ m ) and inactivation (τ h ) of these cations were voltage dependent, and both time constants were greater in the sequence ofI Mn=I Zn〉I Ba=I Sr〉I Ca over the whole voltage range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870371
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  • 12
    Electronic Resource
    Electronic Resource
    Effects of variation of ion and methylation of carrier on the rate constants of macrotetralide-mediated ion transport in lipid bilayers (1982)
    Springer
    The journal of membrane biology 68 (1982), S. 191-206 
    Details
    ISSN: 1432-1424
    Keywords: ion transport ; carriers ; lipid bilayers ; kinetics ; nonactin ; methylation ; macrotetralides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The effects of methylation on the rate constants of carrier-mediated ion transport have been studied on monooleindecane bilayers with K+, Rb+, NH 4 + , and TI+ ions, using the series of homologue carriers, nonactin, monactin, dinactin, trinactin, and tetranactin, each member of the series differing from the previous one by only one methyl group. Measurements of the amplitude and time constant of the current relaxation after a voltage jump over a large domain of voltage and permeant ion concentration, together with a computer curve-fitting procedure, have allowed us, without the help of steady-state current-voltage data, to deduce and compare the values of the various rate constants for ion transport: formation (k Ri) and dissociation (k Di) of the ion-carrier complex at the interface, translocation across the membrane interior of the carrier (k s) and the complex (k is). With the additional information from steady-state low-voltage conductance measurements, we have obtained the value of the aqueous phase-membrane and torus-membrane partition coefficient of the carrier ({ie191-1} and {ie191-2}). From nonactin to tetranactin with the NH 4 + ion,k is, and {ie191-3} are found to increase by factors of 5 and 3, respectively,k Di and {ie191-4} to decrease respectively by factors 8 and 2, whilek Ri andk s are practically invariant. Nearly identical results are found for K+, Rb+, and Tl+ ions.k Ri,k s andk is are quite invariant from one ion to the other except for Tl+ wherek Ri is about five times larger. On the other hand,k Di depends strongly on the ion, indicating that dissociation is the determining step of the ionic selectivity of a given carrier. The systematic variations in the values of the rate constants with increasing methylation are interpreted in terms of modifications of energy barriers induced by the carrier increasing size. Within this framework, we have been able to establish and verify a fundamental relationship between the variations ofk is andk Di with methylation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01872264
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  • 13
    Electronic Resource
    Electronic Resource
    Pressure dependence of the potassium currents of squid giant axon (1982)
    Springer
    The journal of membrane biology 69 (1982), S. 35-40 
    Details
    ISSN: 1432-1424
    Keywords: axon ; hydrostatic pressure ; K currents ; kinetics ; activation volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The effect of pressure upon the delayed, K, voltage-clamp currents of giant axons from the squidLoligo vulgaris was studied in axons treated with 300nm TTX to block the early, Na, currents. The effect of TTX remained unaltered by pressure. The major change produced by pressures up to 62 MPa is a slowing down of the rising phase of the K currents by a time scaling factor which depends on pressure according to an apparent activation volume, ΔV∓, of 31 cm3/mole at 15°C; ΔV∓ increased to about 42 cm3/mole at 5°C. Pressure slightly increased the magnitude, but did not produce any obvious major change in the voltage dependence, of the steady-state K conductance estimated from the current jump at the end of step depolarizations of small amplitude (to membrane potentials,E, ≦20 mV) and relatively short duration. At higher depolarizations, pressure produced a more substantial increase of the late membrane conductance, associated with an apparent enhancement of a slow component of the K conductance which could not be described within the framework of the Hodgkin-Huxley (HH)n 4 kinetic scheme. The apparent ΔV∓ values that characterize the pressure dependence of the early component of the K conductance are very close to those that describe the effect of pressure on Na activation kinetics, and it is conceivable that they are related to activation volumes involved in the isomerization of the normal K channels. The enhancement of the slow component of membrane conductance by pressure implies either a large increase in the conductance of the ionic channels that are responsible for it or a strong relative hastening of their turn-on kinetics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01871239
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  • 14
    Electronic Resource
    Electronic Resource
    Pressure dependence of the sodium currents of squid giant axon (1982)
    Springer
    The journal of membrane biology 69 (1982), S. 23-34 
    Details
    ISSN: 1432-1424
    Keywords: axon ; hydrostatic pressure ; Na currents ; kinetics ; temperature ; activation volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The effects of hydrostatic pressures up to 62 MPa upon the voltage-clamp currents of intact squid giant axons were measured using mineral oil as the pressure transmitting medium. The membrane resistance and capacitance were not appreciably affected over the whole range of pressures explored. The predominant effect of pressure is to slow the overall kinetics of the voltage-clamp currents. Both the early (Na) currents and the delayed (K) ones were slowed down by approximately the same time scale factor, which was in the range of 2 to 3 when pressure was increased from atmospheric to 62 MPa. Finer details of the effects, most evident at moderate depolarizations, are: the apparent initial delay in the turn-on of Na currents is increased by pressureless than is the phase of steepest time variation, and the later decay is slowedmore than is the rising phase. The initial time course of the currents at high pressures can be made to overlap with that at normal pressure by a constant time compression factor, Θm, together with a small, voltage-dependent delay. In a given axon, Θm was fairly independent of voltage, and it increased exponentially with pressure according to an apparent activation volume, ΔV∓, ranging between 32 and 40 cm3/mole. ΔV∓ tended to decrease with increasing temperature. Contrary to what is observed for moderate or large depolarizations, the kinetics of Na inactivation produced by conditioning prepulses of −50 or −60 mV was little affected over the whole range of pressures explored. Inferences about the pressure dependence of the steady-state Na activation were made from the comparison of the plots of early peak currents,I p, versus membrane potential,E. The Na reversal potential,E Na, and the slope of the plots nearE Na did not change significantly with pressure, but the peak Na conductancevs. E relationship was shifted by about +9 mV upon increasing pressure to 62 MPa. Steady-state Na inactivation,h ∞, was slightly affected by pressure. At 62 MPa the midpoint potential of theh ∞ (E) curve,E h, was shifted negatively by about 4 mV, while the slope atE h decreased by about 38%. Under the tentative assumption that pressure directly affects the gating of Na channels, the Na activation data follows a simple Hodgkin-Huxley scheme if the opening of anm gate involves an activation volume of about 58 Å3 and a net volume increase of about 26 Å3. However, a self-consistent description of the totality of the effects of pressure on Na inactivation cannot be obtained within a similar simple context.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01871238
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  • 15
    Electronic Resource
    Electronic Resource
    Na activation delays and their relation to inactivation in frog skeletal muscle (1990)
    Springer
    The journal of membrane biology 118 (1990), S. 233-242 
    Details
    ISSN: 1432-1424
    Keywords: Na channels ; skeletal muscle ; kinetics ; chloramine-T ; electrophysiology ; current inactivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Delays in the development of activation of Na currents were studied using voltage-clamped frog skeletal muscle fibers. Na currents elicited by a depolarizing voltage step from a hyperpolarized membrane potential were delayed in their activation when compared to Na currents elicited from the resting potential. The magnitude of the delay increased with larger hyperpolarizing potentials and decreased with larger depolarizing test potentials. Delays in activation observed following chloramine-T treatment that partially removes inactivation did not differ from delays observed before treatment. Longer exposures of the muscle fiber to chloramine-T led to a complete loss of inactivation, coincident with an elimination of the hyperpolarization-induced delays in activation. Steady-state slow inactivation was virtually unaffected by prolonged exposures of the fibers to chloramine-T that eliminated fast inactivation. The results show that chloramine-T acts at a number of sites to alter both activation and inactivation. Markov model simulations of the results show that chloramine-T alters fundamental time constants of the system by altering both activation and inactivation rate constants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01868607
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  • 16
    Electronic Resource
    Electronic Resource
    Kinetic response of H+-coupled transport to extracellular pH: Critical role of cytosolic pH as a regulator (1989)
    Springer
    The journal of membrane biology 108 (1989), S. 253-261 
    Details
    ISSN: 1432-1424
    Keywords: Chara ; Cl− ; cotransport ; reaction kinetic model ; pH ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary H+-coupled transport in plant and fungal cells is relatively insensitive to external pH (pH o ). H+-coupled Cl− transport at the plasma membrane ofChara corallina was studied to explore the phenomena responsible for this insensitivity. Raising pH o from a control value of 7.5 to 9.0 results in a modest (2.5-fold) decline inJ max and increase inK m . Further increase in pH o results in a selective increase inJ max, in accordance with predictions from a reaction kinetic model of the transport system (Sanders, D., Hansen, U.-P., 1981.J. Membrane Biol. 58:139–153). Increase in cytosolic Cl− concentration ([Cl−] c ) also results in a selective decrease inJ max at pH o =7.5. Quantitative kinetic modeling of the results is not possible if it is assumed that the sole effect of pH o isvia mass action on the binding of external H+ to a transport site. If, instead, the dependence of cytosolic pH (pH c ) on pH o (Smith, F.A., 1984,J. Exp. Bot. 35:1525–1536) is taken into account along with the dependence of Cl− influx on pH c (Sanders, D., 1980,J. Membrane Biol. 53:129–141), then the observed modest changes in Michaelis parameters can be accommodated by a reaction kinetic model. The quantitative parameters of the model yield respective pK a s of the internal and external H+-binding sites=7.85 and 7.2, respective dissociation constants of the internal and external Cl−-binding sites=160 and 40 μm, and an additional, kinetically transparent, H+-binding site with a pK a 〉8.0. The quantitative model independently predicts the response ofJ max andK m to acidic conditions. The results are discussed in terms of the general physiological requirement that fluxes through H+-coupled transport systems are relatively insensitive to environmental variation in pH o . It is proposed that (i) the weak (but finite) dependence of pH c on pH o , coupled with (ii) the strong dependence of H+-coupled transport on pH c are instrumental in endowing H+-coupled transport systems with a relative insensitivity to variation in pH o . This hypothesis might also explain why pH c in plants and fungi is not acutely controlled with respect to variation of pH o .
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    URL: http://dx.doi.org/10.1007/BF01871740
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    Pre-steady-state analysis of the turn-on and turn-off of water permeability in the kidney collecting tubule (1989)
    Springer
    The journal of membrane biology 110 (1989), S. 57-65 
    Details
    ISSN: 1432-1424
    Keywords: fluorescence ; water transport ; vasopressin ; kidney collecting tubule ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Water transport across the mammalian collecting tubule is regulated by vasopressin-dependent water channel insertion into and retrieval from the cell apical membrane. The time course of osmotic water permeability (P f ) following addition and removal of vasopressin (VP) and 8-Br-cAMP was measured continuously by quantitative fluorescence microscopy using an impermeant fluorophore perfused in the lumen. Cortical collecting tubules were subjected to a 120 mOsm bath-to-lumen osmotic gradient at 37°C with 10–15 nl/min lumen perfusion and 10–20 ml/min bath exchange rate. With addition of VP (250 μU/ml), there was a 23±3 sec (sem,n=16) lag in whichP f did not change, followed by a rise inP f (initial rate 1.4±0.2×10−4 cm/sec2) to a maximum of 265±10×10−4 cm/sec. With addition of 8-Br-cAMP (0.01–1mm) there was an 11±2 sec lag. For [8-Br-cAMP]=0.01, 0.1 and 1mm, the initial rate ofP f increase following the lag was (units 10−4 cm/sec2): 1.1±0.1, 1.2±0.1 and 1.7±0.3. MaximumP f was (units 10−4 cm/sec): 64±4, 199±9 and 285±11. With removal of VP,P f decreased to baseline (12×10−4 cm/sec) with aT 1/2 of 18 min; removal of 0.1 and 1mm 8-Br-cAMP gaveT 1/2 of 4 and 8.5 min. These results demonstrate (i) a brief lag in theP f response, longer for stimulation by VP than by 8-Br-cAMP, representing the transient build-up of biochemical intermediates proximal to the water channel insertion step, (ii) similar initialdP f /dt (water channel insertion) over a wide range of [8-Br-cAMP] and steady-stateP f values, and (iii) more rapidP f decrease with removal of 8-Br-cAMP than with VP. These pre-steady-state results define the detailed kinetics of the turn-on and turn-off of tubuleP f and provide kinetic evidence that the rate-limiting step for turn-on ofP f is not the step at which VP regulates steady-stateP f . If water channel insertion is assumed to be the rate-limiting step in the turn-on ofP f , these results raise the possibility that water channels must be activated following insertion into the apical membrane.
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    URL: http://dx.doi.org/10.1007/BF01870993
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    Assessment of inhibition kinetics of the growth of strain P5 on pentachlorophenol under steady-state conditions in a nutristat (1996)
    Springer
    Archives of microbiology 165 (1996), S. 194-200 
    Details
    ISSN: 1432-072X
    Keywords: Key words Auxostat ; Batch culture ; Chemostat ; Continuous culture ; Fermentation control ; Inhibition ; kinetics ; Nutristat ; On-line measurement ; Pentachlorophenol ; Pollutant ; Sphingomonas ; Steady-state conditions ; Toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A bacterium degrading pentachlorophenol (PCP) as the only source of carbon and energy was grown in a “nutristat”, i.e., a continuous culture with on-line measurement and control of the substrate concentration. We improved the PCP nutristat by incorporation of a personal computer with a proportional integral derivative (PID) algorithm for controlling the medium feed pump. The controlled value deviated from the average (set-point) value by 1% maximally. In the PCP nutristat (30°C), the steady-state dilution rate, and hence, specific growth rate, showed a maximum value of 0.142 ± 0.004 h–1 at set-point PCP concentrations between 37 and 168 μM. At PCP concentrations above 168 μM, the steady-state growth rate decreased because of inhibition. The growth yield coefficient was not seriously affected by the PCP concentration, suggesting that uncoupling was not the inhibitory mechanism. It was concluded that the PCP nutristat is very useful for establishing steady-state conditions that maintain growth-inhibitory PCP concentrations and high cell concentrations, conditions for which the chemostat is not suitable.
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    URL: http://dx.doi.org/10.1007/BF01692861
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    Bioavailability of a new effervescent tablet of ibuprofen in healthy volunteers (1997)
    Springer
    European journal of clinical pharmacology 52 (1997), S. 505-506 
    Details
    ISSN: 1432-1041
    Keywords: Key words Ibuprofen; effervescent tablets ; kinetics ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002280050327
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  • 20
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    Improved effect of glibenclamide on administration before breakfast (1982)
    Springer
    European journal of clinical pharmacology 21 (1982), S. 403-408 
    Details
    ISSN: 1432-1041
    Keywords: glibenclamide ; diabetes ; insulin ; kinetics ; blood glucose ; relationship to meals ; absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In an attempt to assess whether intake of glibenclamide before meals would improve its therapeutic capacity, the present investigation compared the effect of glibenclamide 2.5mg t.i.d. given before and together with meals. In addition, these effects were compared with that of glibenclamide given as a single morning dose of 7.5mg. The subjects studied were six Type 2 diabetics not previously exposed to sulphonylurea drugs. Irrespective of dosage and mode of administration, addition of glibenclamide to a standardized breakfast, lunch and dinner enhanced plasma IRI concentrations and reduced blood glucose concentrations as compared to administration of meals without the drug. The different modes of glibenclamide administration did not differ significantly with respect to IRI responses. However, the blood glucose reduction after breakfast was significantly greater when glibenclaimde 2.5mg had been given before the meal than when 2.5 or 7.5mg were given with the meal; a similar, but non-significant tendency was observed after lunch; no consistent difference was seen after dinner. Food intake did not affect glibenclamide kinetics. It appears that administration of glibenclamide 2.5mg before breakfast improved glucose utilization following the breakfast load, due to earlier attainment of an effective concentration of glibenclamide.
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  • 21
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    Chloroquine kinetics in the undernourished (1983)
    Springer
    European journal of clinical pharmacology 24 (1983), S. 273-276 
    Details
    ISSN: 1432-1041
    Keywords: undernourished ; chlorquine ; kinetics ; plasma levels ; red cell uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The plasma and whole blood kinetics of chloroquine was studied in 7 normal and 8 undernourished subjects following a single oral dose of 600 mg. The terminal half-lives were similar in both groups. The AUC was also similar in the 2 groups, even though a higher dose per kg body weight was administered to the undernourished. This was probably because of faster clearance in this group. Chloroquine uptake by erythrocytes, its main site of action in malaria, was also comparable in the two groups. The plasma concentration of chloroquine over a period of time was found to be similar in 4 normal and 4 undernourished subjects following administration of 1.5 g of the drug in divided doses. The undernourished appear, therefore, to handle chloroquine in such a way that they do not suffer a greater risk of toxicity than normals.
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  • 22
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    Elimination of azlocillin in patients with biliary t-tube drainage (1982)
    Springer
    European journal of clinical pharmacology 22 (1982), S. 435-439 
    Details
    ISSN: 1432-1041
    Keywords: azlocillin ; kinetics ; biliary excretion ; liver dysfunction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetic of azlocillin was followed in five elderly patients after biliary surgery. Total clearance was 138.6±17.7 ml/min when 2.0 g was given as an i.v. bolus injection. The half-life of the β-phase averaged 110 min. The total clearance and the half-life of azlocillin were influenced by slight impairment of renal function (creatinine clearance 59.4±13.6 ml/min). In patients with normal liver function biliary excretion of the drug amounted to 5.3±2.8% of the dose (n=3) and the kinetics of biliary excretion were linear. In contrast, in two patients with impaired liver function biliary excretion was 0.2% and 0.5% of the dose, and kinetic analysis of biliary excretion rates revealed at least one zero order step in the excretion process. Renal excretion of the drug amounted to 45.0±17.7% of the dose, which means that 50% of the total clearance of azlocillin has to be accounted for by metabolic clearance.
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    URL: http://dx.doi.org/10.1007/BF00542549
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    Disposition of the antiepileptic oxcarbazepine and its metabolites in healthy volunteers (1982)
    Springer
    European journal of clinical pharmacology 22 (1982), S. 545-551 
    Details
    ISSN: 1432-1041
    Keywords: oxcarbazepine ; kinetics ; disposition ; metabolites ; renal excretion ; volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Oxcarbazepine (oxcarb) 600 and 900 mg (2360 and 3540 µmol) was taken by 3 volunteers (2 ♀, 1 ♂; 45–67 kg; age 22–34 years) after an overnight fast. Blood, saliva and urine were collected for the next 72 h for assay of oxcarb, 10,11-dihydro-10-hydroxy-carbamazepine (OHcarb), and 10,11-dihydrotrans-10,11-dihydroxy-carbamazepine (diol). Oxcarb reached a maximum level of about 1 µg/ml (3.93 µmol/l) within 1 h and dropped below the detection limit (0.1 µg/ml=0.39 µmol/l) within 3 h. The active metabolite OHcarb appeared in the blood before oxcarb and reached the higher maximum level of 7.4 µg/ml (29 µmol/l) after 7 h. Thereafter serum levels decreased with a t1/2 of about 25 h, and after 40 h with a t1/2 of 9 h, the latter agreeing with the renal excretory t1/2 calculated from the urine data (10 h). The ratio of OHcarb concentration in saliva to that in plasma varied considerably (0.3–1.7; median 1; r〉0.9), whereas that of blood to plasma was 1.25 with only small variation (r〉0.98); OHcarb concentrations in erythrocytes were 50% higher than in plasma. Diol was detected in blood (maximum level 0.5 µg/ml=1.84 µmol/l) in 2 volunteers. 45% of the dose could be recovered in urine (Oxcarb 5%, OH-carb 36%, Diol 4%). Whereas Oxcarb was completely conjugated, only 25% of OHcarb was conjugated and diol was unconjugated.
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    URL: http://dx.doi.org/10.1007/BF00609629
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  • 24
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    Comparison of non-kinetic and kinetic approaches to individualization of gentamicin dosage (1990)
    Springer
    European journal of clinical pharmacology 39 (1990), S. 155-159 
    Details
    ISSN: 1432-1041
    Keywords: Gentamicin ; Dosage ; kinetics ; dose individualization ; dose prediction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A prospective study was carried out in 40 acutely ill patients to compare the non-kinetic and kinetic approaches to individualization of the dosage regimen of gentamicin. The patients were divided into two equal groups. For the non-kinetic group, the doses were derived from the physician's personal experience, on a mg/kg basis, and by use of nomograms. The total daily dose ranged from 1.43 to 4.5 mg/kg. Based on serum concentration measurements, the dosage regimen for individual patient was calculated by Sawchuk-Zaske's method. The calculated doses were compared to the prescribed doses in each patient. Of the patients on empirically prescribed doses 65% received 36% more drug than the calculated dose and 20% received 36% less than the calculated dose. The calculated dosing intervals were greater than the recommended intervals in 60% of the patients. The gentamicin trough concentration was 〉 2 μg/ml in 70% of the patients. There was a significant tendency to overdosage of the patients. For the kinetic group, following administration of the calculated dose, the steady-state peak and trough concentrations in each patient were measured. The correlation of measured to predicted steady-state serum concentrations was excellent (r=0.9968, p〈0.05). About 85% of the served trough concentrations and 90% of the peak values fell within the therapeutic range. The mean of the prediction error (ME), mean absolute error (MAE), mean squared error (MSE), and root mean squared error (RMSE) of the trough and peak concentrations were calculated. The 95% confidence interval of the ME for the trough and peak concentrations included zero, which shows that the prediction was not significantly biased. A significant relationship between gentamicin clearance and the ratio of the peak and trough concentrations achieved to the administered dose (r=0.873, 0.916 for trough and peak, respectively) was found. The findings suggest that the individualized approach to dosage determination using pharmacokinetic principles, in conjunction with daily monitoring of serum gentamicin concentrations, may provide safe and effective therapy.
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    Absorption of intramuscular phenobarbitone in children with severe falciparum malaria (1992)
    Springer
    European journal of clinical pharmacology 42 (1992), S. 107-110 
    Details
    ISSN: 1432-1041
    Keywords: Phenobarbitone ; Cerebral malaria ; P.falciparum ; kinetics ; drug absorption ; children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The absorption of intramuscular phenobarbitone 7 mg·kg−1 was studied in 11 Karen children aged between 1.7 and 11 y with severe falciparum malaria. Eight of the children were comatose. Clinical findings were compared with those in 9 further children with severe malaria of similar age range (four of whom were unconscious), who received an identical placebo. One child, who had received placebo, had repeated convulsions and died 1 h after admission to hospital. The remainder made an uncomplicated recovery. There were no convulsions subsequent to treatment, although the study was too small to assess anticonvulsant efficacy. There was no observable toxicity, but phenobarbitone recipients had a significant tendency to deepen in their level of coma or to become sleepy within the 4 h after drug administration. Phenobarbitone was rapidly absorbed, reaching a mean (range) peak concentration of 34.2 [29.3–42.6] μmol·l−1 in a median (range) of 4 (2.5–12) h. These values are comparable to those previously reported in healthy children and in children with febrile convulsions. Intramuscular phenobarbitone is well absorbed in children with severe malaria; the optimum prophylactic anticonvulsant dose remains to be determined.
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    URL: http://dx.doi.org/10.1007/BF00314929
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    Influence of food and age on the single-dose kinetics and effects of tolbutamide and chlorpropamide (1980)
    Springer
    European journal of clinical pharmacology 17 (1980), S. 285-293 
    Details
    ISSN: 1432-1041
    Keywords: tolbutamide ; chlorpropamide ; kinetics ; food ; age ; blood glucose ; plasma insulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The influence of food intake (standardized breakfast) on the oral single-dose kinetics and effects of tolbutamide (0.5 g) and chlorpropamide (250 mg) was investigated in young, healthy volunteers. The single-dose kinetics of the two drugs was also studied in elderly healthy subjects. There was great interindividual variation in the elimination rate of both drugs, but food intake influenced neither their AUCs nor their rates of absorption and elimination. The peak concentration of chlorpropamide, but not that of tolbutamide, was reduced by food intake. The peak concentrations of serum tolbutamide were approximately doubled by an increase in dose from 0.5 to 1.0 g, and from 1.0 to 2.0 g. At no time did tolbutamide 0.5 g affect the plasma insulin level, neither in the fasting nor in the non-fasting state. However, this dose did reduce the blood glucose level during fasting and the increase in blood glucose in response to the meal. The latter effect was recorded within 30 min, when the serum level of tolbutamide still was close to zero. Plasma insulin concentrations did increase within 30 min after a higher dose of tolbutamide (1.0 g), when the serum concentration of tolbutamide was about 50 µmol/l. Between 2.5 and 8 h after administration of chlorpropamide 250 mg, serum drug concentrations were lower than those following tolbutamide 0.5 g. The blood glucose response was smaller and occurred later, being significant at 2 h, when the serum concentration of the drug was about 70 µmol/l. There was no significant change in plasma insulin. There was no significant pharmacokinetic difference between young and elderly subjects, except that the peak concentration of tolbutamide was higher in the latter. It appears that both for tolbutamide and chlorpropamide there is great interindividual variation in drug disposition, but food intake does not influence the bioavailability of either drug. The effect of any particular drug concentration seems dependent upon the blood glucose level and hence upon the elapsed time since the last meal. Both drugs can reduce blood glucose without an alteration in the peripheral blood concentration of insulin. This may reflect an extrapancreatic effect of the drugs, but it could also be an expression of increased insulin secretion, which is not detected because of enhanced hepatic degradation of the hormone released into the portal circulation. The observations made in young individuals are also probably relevant for elderly subjects.
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    Pinazepam: A precursor of N-desmethyldiazepam (1982)
    Springer
    European journal of clinical pharmacology 22 (1982), S. 225-228 
    Details
    ISSN: 1432-1041
    Keywords: pinazepam ; N-desmethyldiazepam ; kinetics ; metabolism ; human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The plasma profile of a single oral dose of pinazepam 10 mg was studied in 6 healthy male volunteers, aged 26 to 31 years. The concentrations of the parent compound and of its metabolite in plasma were measured by gas-chromatography. The peak plasma levels of pinazepam was 36.8±5.1 ng/ml and of N-desmethyldiazepam 150±13.3 ng/ml. The plasma concentration of the metabolite become higher than that of the parent compound shortly after administration, suggesting that pinazepam acts as a prodrug.
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    URL: http://dx.doi.org/10.1007/BF00545219
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    Bioavailability of acetylsalicylic acid and salicylic acid from rapid-and slow-release formulations, and in combination with dipyridamol (1982)
    Springer
    European journal of clinical pharmacology 22 (1982), S. 309-314 
    Details
    ISSN: 1432-1041
    Keywords: acetylsalicylic acid ; salicylic acid ; dipyridamol ; bioavailability ; kinetics ; rapid- and slow-release formulations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Acetylsalicylic acid (ASA) is a strong, irreversible inhibitor of platelet aggregation, but loses this activity following first-pass deacetylation to salicylic acid (SA). In order to compare the bioavailability of unchanged ASA from rapid- and slow-release formulations, the single-dose concentration profiles of ASA and SA were studied in healthy volunteers following intake of two different rapid-release (conventional and effervescent tablets) and three different slow-release (microencapsulated ASA in tablets and in capsules, and enteric-coated tablets) formulations of ASA, and of one slow-release formulation of sodium salicylate. Since anti-platelet therapy with ASA is often combined with dipyridamol, the influence of this drug was also examined. The concentrations of ASA and SA were measured by high-pressure liquid chromatography. While the bioavailability of SA from the 5 ASA formulations was essentially equal and similar to that of the salicylate formulation, the bioavailability and peak concentrations of ASA appeared to be the much greater after rapid-release than after slow-release formulations. Indeed, ASA was only rarely detected in systemic blood following intake of slow-release ASA. Co-administered dipyridamol did not significantly influence the kinetics of ASA or SA. It appears that rapid-release formulations of ASA should be prefered in anti-platelet therapy, either alone or in combination with dipyridamol.
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    URL: http://dx.doi.org/10.1007/BF00548398
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    The single dose kinetics of chloroquine and its major metabolite desethylchloroquine in healthy subjects (1984)
    Springer
    European journal of clinical pharmacology 26 (1984), S. 521-530 
    Details
    ISSN: 1432-1041
    Keywords: chloroquine ; malaria ; rheumatoid disease ; kinetics ; major metabolite ; optimal dosage ; therapeutic regime ; monodesethylchloroquine ; bidesethylchloroquine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The kinetics and disposition of chloroquine (CQ) and its metabolite monodesethylchloroquine (CQM) were investigated in 5 healthy volunteers after incremental (150–300–600 mg CQ base) single oral doses of CQ. The analytical method used (HPLC and fluorescence detection) is the most sensitive known method for CQ and CQM. Plasma and whole blood concentrations of CQ, CQM and a third metabolite, bidesethylchloroquine (CQMM), were determined. The kinetics of CQ was found to be unique. The best fit was obtained by a multicompartmental model. The biological half-life appeared to be between 30–60 days; the volume of distribution (Vd) was ∼ 800l/kg, and the clearance ∼ 11/h/kg when calculated from plasma data. The whole blood concentrations were ∼ 8–10 times higher than in plasma, and consequently the Vd and whole blood clearance were ∼ 10 times lower. The kinetics changed as the dose was increased. An indication of capacity-limited steps in CQ disposition was found, as the rate constants decreased even though the clearance remained the same. The intrinsic half-life of CQM was 1/4 of that of CQ, but was prolonged after the highest dose of CQ. The present knowledge of CQ kinetics could provide a basis for revision of current dosage regimens in malaria suppression and rheumatoid disease to ensure efficacious and safe therapy.
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    Cimetidine-phenytoin interaction: Effect on serum phenytoin concentration and antipyrine test (1981)
    Springer
    European journal of clinical pharmacology 21 (1981), S. 215-220 
    Details
    ISSN: 1432-1041
    Keywords: phenytoin ; cimetidine ; antipyrine test ; drug interaction ; drug metabolism ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In a prospective study in nine patients the effects of phenytoin and of cimetidine (1000mg/day) + phenytoin on the antipyrine test and serum phenytoin concentrations were studied. Serum phenytoin increased from the steady state level of 5.7±1.3 mg/l to 9.1±1.4mg/l after three weeks on cimetidine (p〈0.01), and fell to 5.8±1.2 mg/l within two weeks after withdrawal of cimetidine. The protein binding of phenytoin was not changed by cimetidine. After use of phenytoin for 2–4 months, antipyrine clearance increased from 0.67±0.06ml/min/kg to 1.61±0.22 ml/ min/kg, and antipyrine half-live fell from 10.9±1.3h to 4.5±0.6h as compared to the values before phenytoin treatment (p〈0.01). After three weeks combined use of cimetidine and phenytoin, antipyrine clearance was decreased to 1.01±0.07 ml/min/kg and antipyrine half-life was prolonged to 6.1±0.5h, (p〈0.01) compared to the values on phenytoin alone. The distribution volume of antipyrine was not affected by phenytoin nor by cimetidine + phenytoin. The half-life of cimetidine was 2.8±0.3h in the patients on longterm phenytoin treatment. There was a significant positive correlation (p〈0.001) between the increase in serum phenytoin concentration and the prolongation of antipyrine half-life caused by cimetidine. Thus, cimetidine increases serum phenytoin concentration, very probably by inhibiting its metabolism. Care should be taken in the concomitant use of cimetidine and phenytoin, and the dose of phenytoin should be modified according to the clinical symptoms and serum phenytoin concentrations.
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    URL: http://dx.doi.org/10.1007/BF00627923
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    Effect of rifampicin treatment on the kinetics of mexiletine (1982)
    Springer
    European journal of clinical pharmacology 23 (1982), S. 261-266 
    Details
    ISSN: 1432-1041
    Keywords: mexiletine ; rifampicin ; kinetics ; enzyme induction ; excretion ; antipyrine clearance ; dosage adjustment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary To study the effects of enzyme induction on its pharmacokinetics, a single oral dose of the new antiarrhythmic agent mexiletine hydrochloride 400 mg was administered to 8 healthy volunteers before and after treatment with rifampicin 300 mg b.i.d. for ten days. The absorption and distribution of mexiletine were not changed after rifampicin, but its elimination half-life fell from 8.5±0.8 h (mean±SE) to 5.0±0.4 h (p〈0.01), and its nonrenal clearance increased from 435±68 ml/min to 711±101 ml/min (p〈0.01). The mean renal clearance of mexiletine did not change, but it showed an exponential correlation with urinary pH. The amount of unchanged mexiletine excreted in urine over two days decreased from 32±7 to 18±3 mg (p〈0.01). The half-life of antipyrine fell from 11.8±0.4 to 5.5±0.3 h and its clearance increased from 40±3 ml to 74±3 ml/min (p〈0.01). There was a significant (p〈0.05) positive linear correlation between both the half-lives and the clearances of antipyrine and mexiletine. The clearances were positively correlated with serum γ-glutamyl transpeptidase. The results suggest that the dosage of mexiletine should be adjusted when enzyme inducing drugs are started or stopped during therapy with it.
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    URL: http://dx.doi.org/10.1007/BF00547565
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    Effect of quinidine on digoxin bioavailability (1983)
    Springer
    European journal of clinical pharmacology 24 (1983), S. 41-47 
    Details
    ISSN: 1432-1041
    Keywords: quinidine ; digoxin ; interaction ; kinetics ; absorption ; elimination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary To evaluate the possible effect of quinidine on digoxin bioavailability, the steady state digoxin kinetics was examined with and without concomitant quinidine therapy, in 7 cardiac patients after simultaneous administration of oral digoxin and intravenous [3H]-digoxin. In the presence of quinidine, the absorption rate constant of digoxin (ka) increased from 2.72±1.04 to 3.53±1.34 h−1 (p〈0.05), whereas lag time and peak time decreased from 0.16±0.10 to 0.05±0.04 h (p〈0.05) and from 0.92±0.27 to 0.69±0.19 h (p〈0.02), respectively. Predose plasma digoxin increased from 0.41±0.25 to 0.70±0.31 ng/ml (p〈0.02), while peak plasma digoxin increased from 0.93±0.34 to 1.63±0.46 ng/ml (p〈0.02). The systemic availability of digoxin increased from 68.48±13.35 to 79.09±14.89% (p〈0.05) in the presence of quinidine. Quinidine had no effect on the biotransformation pattern of digoxin, as assessed by thin layer chromatography. Quinidine increases the rate and extent of digoxin absorption, and this interaction contributes significantly to the elevation in plasma digoxin during both its distribution and elimination phases.
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    URL: http://dx.doi.org/10.1007/BF00613925
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    Effect of two antacids on the bioavailability of paracetamol (1985)
    Springer
    European journal of clinical pharmacology 29 (1985), S. 251-253 
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    ISSN: 1432-1041
    Keywords: paracetamol ; antacids ; acetaminophen ; bioavailability ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of two antacids on the bioavailability of paracetamol has been investigated in 12 young healthy volunteers. Following a random cross over design, each subject swallowed, on three separate occasions, one weak apart, 500 mg paracetamol alone, or together with two different aluminium hydroxide, magnesium hydroxide preparations (Dimalan and Maalox). Plasma paracetamol levels were measured by HPLC. The bioavailability of paracetamol was not altered by either antacid, but they both delayed the time to peak plasma concentration (0.85 h; 1.43 h; 1.25 h, without antacid, with Dimalan and with Maalox respectively). The peak plasma concentration was not affected by concurrent antacid administration.
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    Kinetics of atrial natriuretic peptide in young and elderly subjects (1992)
    Springer
    European journal of clinical pharmacology 42 (1992), S. 449-452 
    Details
    ISSN: 1432-1041
    Keywords: Atrial natriuretic peptide ; kinetics ; ageing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary To study the influence of age on the kinetics of atrial natriuretic peptide (ANP) in man, human (99–126) ANP 2.0 μg·min−1 was infused IV for 60 min in 8 healthy young (18 to 25 y) and 9 healthy elderly (71 to 84 y) subjects. Both baseline ANP values and the levels at the end of infusion were higher in the elderly subjects. The mean residence time of ANP in the two age groups was not significantly different, whereas total body clearance (CL) was markedly diminished in the elderly as compared to the young subjects (mean±SD 3.1±1.0 l·min−1 and 6.2±4.1 l·min−1, respectively). The apparent volume of distribution at steady state was lower in the elderly than in the young, but the difference was not significant (mean±SD 44±19 and 103±111, respectively. The decrease in CL largely explained the higher ANP levels found in the elderly subjects. The MRT and the plasma half-life of the terminal phase did not differ between the two groups. In the elderly but not in the young subjects the calculated endogenous creatinine clearance was closely correlated with the CL (r=0.90, P〈0.001), thereby emphasizing the importance of the kidney in the metabolic clearance of ANP in the elderly.
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    Interaction of talinolol and sulfasalazine in the human gastrointestinal tract (1992)
    Springer
    European journal of clinical pharmacology 42 (1992), S. 461-462 
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    ISSN: 1432-1041
    Keywords: Talinolol ; Sulfasalazine ; β-adrenoceptor-blocking drugs ; absorption ; drug interaction ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The absorption of talinolol (TA) 50 mg was investigated without and together with the co-administration of sulfasalazine (SASP) 4 g in 11 healthy young volunteers, in order to clarify gastrointestinal transit of TA. Without SASP, the tmax of TA was 2.8 h, Cmax was 112 ng·ml−1 and the half life was 12 h; the AUCo-t was 958 ng·ml−1·h. In the case of concomitant administration of SASP, TA was found only in serum from 3 individuals, with a Cmax of 23 ng·ml−1 and a mean AUCo-t of 84 ng·ml−1·h. TA was not detectable in 5 subjects and it was at the limit of detection (2 ng·ml−1) in 3 subjects. Pharmacokinetic analysis was not possible in any of those individuals. The reason for the interaction appears to be the adsorption of TA by SASP. An interval of 2–3 h should elapse between giving SASP and other drugs.
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    Dimyristoylphosphatidic acid/cholesterol bilayers (1986)
    Springer
    European biophysics journal 13 (1986), S. 343-353 
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    ISSN: 1432-1017
    Keywords: Lipid/cholesterol ; phase transition ; kinetics ; second order transition ; pressure jump relaxation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Lipid bilayers and monolayers composed of dimyristoylphosphatidic acid (DMPA) and cholesterol were characterized by differential scanning calorimetry and film balance measurements. Increasing cholesterol content decreases the bilayer phase transition temperature and enthalpy in a manner similar to that observed before for other lipid/cholesterol systems. In monomolecular films at the air-water interface cholesterol exhibits the well known condensing effect in the liquid-expanded phase, while the liquid-condensed phase is less affected. As with the bilayer phase transition, the transition temperature and change in area at the liquid-condensed to liquid-expanded phase transition, as measured from isobars at 25 dynes/cm, decreases with increasing cholesterol content. The kinetics of the phase transition of DMPA/cholesterol bilayers were measured using the pressure jump relaxation technique with optical detection. Three relaxation times were observed. The relaxation times and amplitudes pass through maximum values at the transition midpoint. With increasing cholesterol content the maximum values of the relaxation times decrease but not in a linear fashion. The time constants display an intermediate maximum at ca. 10% to 12 mol% cholesterol. This observation is discussed in terms of a possible change in the nature of the phase transition from first-order with phase separation to a continuous second-order transition. The dependence of the relaxation amplitudes on cholesterol content gave evidence for nucleation being the rate limiting step for the transition in this particular system.
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    Arachidonic acid — Induced platelet aggregation and prostanoid formation in whole blood in relation to plasma concentration of indomethacin (1985)
    Springer
    European journal of clinical pharmacology 28 (1985), S. 163-169 
    Details
    ISSN: 1432-1041
    Keywords: indomethacin ; platelet aggregation ; prostanoids ; plasma concentration ; arachidonic acid ; thromboxane B2 ; 6-keto-prostaglandin F1α ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A single oral dose of indomethacin 1 mg/kg was given to 6 male and 6 female volunteers. The formation of thromboxane B2 (TXB2) and 6-ketoprostaglandin F1α (6-keto-PGF1α) in clotting whole blood was measured by radioimmunoassay, and platelet aggregation induced by archidonic acid (AA) was measured with a plasma aggregometer. The results were related to the concomitant plasma concentration of indomethacin. The maximum plasma concentration ranged between 3.24 and 8.11 µg/ml and the elimination half-life between 4 and 11 h. Formation of the prostanoids was reversibly inhibited, with maximum suppression when the drug concentration in plasma exceeded 0.5–1.0 µg/ml; the IC50 was approximately 0.1 µg/ml. Platelet aggregation was also reversibly inhibited. The correlation between the formation of prostanoids and the different phases of the aggregatory response to exogenous AA is discussed.
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    Influence of sulfonylureas on the secretion, disposal and effect of insulin (1982)
    Springer
    European journal of clinical pharmacology 22 (1982), S. 27-32 
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    ISSN: 1432-1041
    Keywords: sulfonylureas ; diabetes ; chlorpropamide ; glipizide ; C-peptide ; insulin ; blood glucose ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The influence of sulfonylurea on the secretion, disposal and effect of insulin was studied in 9 Type 2 diabetics during 3 one-month courses of treatment with a) chlorpropamide (t1/2〉24 h) once daily, b) glipizide (t1/2=2–4 h) once daily, and c) glipizide in divided doses. Food intake by each patient was identical during each period. Blood concentrations of immunoreactive insulin (IRI) and C-peptide (radioimmunoassays), and of glucose (enzymatic assay), chlorpropamide (gas chromatography) and glipizide (high-pressure liquid chromatography) were determined before and after breakfast and lunch on the 4th day of each examination period. All comparisons were intraindividual. Despite the lunch-time dose of glipizide given during the divided dose treatment, once-daily administration of this drug led to higher drug concentrations not only after breakfast but also for the first few hours after lunch. Divided dosage, on the other hand, led to higher concentrations later. In contrast to once-daily dosage, continuous exposure to glipizide was found in most patients. Chlorpropamide gave the most continuous sulfonylurea exposure. The blood glucose levels were inversely related to the concurrent sulfonylurea concentrations; glucose levels after breakfast and lunch were lowest during once-daily glipizide, whereas the fasting level was lowest during chlorpropamide treatment. The IRI response to breakfast was 60%–70% higher during once-daily glipizide than during the other two treatments, but the C-peptide responses to breakfast were almost identical. Thus, the greater after-breakfast availability of peripheral insulin appeared to be due to an effect of glipizide on the extrapancreatic disposal of the hormone.
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    Pharmacokinetics of furosemide in neonates (1982)
    Springer
    European journal of clinical pharmacology 22 (1982), S. 39-45 
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    ISSN: 1432-1041
    Keywords: furosemide ; neonates ; kinetics ; placental transfer ; intravenous therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of furosemide was evaluated in 12 newborns who received the drug transplacentally, and in 21 neonates who received it directly for therapeutic reasons. In the first group, the apparent plasma half-lives ranged from 96 to 6.8 h with a significant inverse relationship (p〈0.01) between the gestational age and the elimination rate. In two cases a clear effect on diuresis was also observed. In the neonates receiving the drug i.v. for therapeutic reasons, the elimination kinetics appeared to follow a two-compartment open model, with a significant difference in the therminal plasma half-life between premature (26.8±12.2 h) and full-term newborns (13.4±8.6 h). In this group no relationship was observed between elimination rate and either gestational or conceptional age. In the case of repeated administration, an increase in plasma clearance and reduction in t1/2 β was noticed.
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    Kinetics and metabolism of (+)-, (−)- and (±)-bufuralol (1982)
    Springer
    European journal of clinical pharmacology 23 (1982), S. 529-533 
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    ISSN: 1432-1041
    Keywords: beta-blocker ; bufuralol ; enantiomers ; kinetics ; metabolism ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Single oral doses of (+)-, (−)- and (±)-bufuralol were administered to a healthy volunteer to compare the disposition and metabolism of the individual isomers and the racemate. Plasma levels and area under plasma curve (AUC) of the active isomer, (−)-bufuralol, were higher than those of the (+)-isomer; plasma clearance was correspondingly lower. Intermediate values were found for the racemate. The elimination half-life of (−)-bufuralol was shorter than that of (+)-bufuralol, but similar to the racemate. Both isomers were cleared almost entirely by metabolism. The main metabolic pathway for (−)-bufuralol was aromatic hydroxylation, whereas the principal route for (+)-bufuralol was conjugation. Phenol metabolites in the systemic circulation were present mainly as conjugates. Both isomers also underwent aliphatic hydroxylation. This pathway was more favoured by the (+)-isomer, although plasma levels and AUC of the principal product, 2′-hydroxy-bufuralol, were almost identical for the two forms. Major differences in metabolic fate thus had relatively little effect on the disposition of pharmacologically active metabolites.
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    The long-term effect of verapamil on plasma digoxin concentration and renal digoxin clearance in healthy subjects (1982)
    Springer
    European journal of clinical pharmacology 22 (1982), S. 123-127 
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    ISSN: 1432-1041
    Keywords: digoxin ; verapamil ; digoxin-verapamil interaction ; kinetics ; plasma level ; renal clearance ; extra-renal clearance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Single-dose investigations in healthy subjects have demonstrated substantial impairment of renal and extrarenal clearance of digoxin during coadministration of verapamil. A longitudinal study has been performed to assess the changes in digoxin disposition during long-term verapamil therapy. After one week of verapamil 240 mg/d mean plasma digoxin had risen from 0.21±0.01 ng/ml (SE) to 0.34±0.01 ng/ml (p〈0.01), and renal digoxin clearance had fallen from 197.57±17.37 ml/min to 128.20±10.33 ml/min (p〈0.001). These changes gradually subsided, and after six weeks, renal digoxin clearance had normalized and plasma digoxin had declined to 0.27±0.02 ng/ml (NS). The 24-h urinary recovery of digoxin increased from 46.46±3.23% before to 69.78±3.69% (p〈0.001) after six weeks of verapamil co-administration, and this elevation persisted throughout the study. The verapamil-induced suppression of renal digoxin elimination disappears over a few weeks of drug exposure, whereas the inhibition of the extrarenal clearance of digoxin seems to persist.
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    Increased oral clearance of metoprolol in pregnancy (1983)
    Springer
    European journal of clinical pharmacology 24 (1983), S. 217-220 
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    ISSN: 1432-1041
    Keywords: metoprolol ; pregnancy ; hypertension ; kinetics ; pre-eclampsia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The disposition of oral metoprolol was studied in 5 women during the last trimester of pregnancy and 3 to 5 months after delivery. After a single oral dose of 100 mg the individual peak plasma concentration in the pregnant state was only 20–40% of that after pregnancy. The plasma half-lives of metoprolol were about the same during (average 1.3 h) and after pregnancy (average 1.7 h). By contrast, the area under the plasma concentration versus time curve was much smallerduring (mean 262 nmol/l×h) thanafter (mean 1298 nmol/l×h) pregnancy, resulting in an average apparent oral clearance (Clo) of metoprolol that was 4.4times higher during (362 ml×kg−1 body-weight×min−1) than after pregnancy. The increased Clo in pregnancy is assumed to be due to enhanced hepatic metabolism of the drug. The possible clinical consequence of the difference in the disposition of metoprolol is discussed.
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    Pharmacokinetics of metoprolol and its metabolite α-OH-metoprolol in healthy, non-smoking, elderly individuals (1983)
    Springer
    European journal of clinical pharmacology 24 (1983), S. 221-226 
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    ISSN: 1432-1041
    Keywords: metoprolol ; age ; disposition ; elderly subjects ; kinetics ; metabolism ; alpha-OH-metoprolol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The absorption and disposition of metoprolol have been evaluated in 10 healthy, non-smoking, elderly individuals (mean age 73.1 years) by simultaneous determination of [3H]-metoprolol and unlabelled metoprolol. The labelled drug was given as an intravenous tracer dose, immediately followed by oral metoprolol 25 mg. The experiment was preceded by administration of metoprolol 25 mg b.i.d. for 3 days. The volume of distribution, elimination half-life and total body clearance were almost the same as previously observed in healthy, young subjects. The mean systemic availability was about 39% in the elderly, which is lower than the mean of 55% observed in a control group of young volunteers who received 50 mg b.i.d. In the elderly, the mean plasma concentration of α-OH-metoprolol was about twice as high as that of the parent drug, whereas the opposite was true of the control group. The results indicate that age-related physiological changes have a negligible effect on the pharmacokinetics of metoprolol.
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    Effect of activated charcoal on absorption of tolbutamide and valproate in man (1983)
    Springer
    European journal of clinical pharmacology 24 (1983), S. 243-246 
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    ISSN: 1432-1041
    Keywords: tolbutamide ; valproate ; intoxication ; activated charcoal ; inhibition of absorption ; sulphonylureas ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The claim that activated charcoal should be ineffective or even contraindicated in intoxication due to tolbutamide is based only on limited in vitro studies. To test the claim, the effect of activated charcoal 50 g on the absorption of tolbutamide and, as a reference, of sodium valproate, was studied in 6 healthy volunteers. Each volunteer swallowed tolbutamide 500 mg and sodium valproate 300 mg with 50 ml water 1 h after a light breakfast, and within 5 min they took in randomized order either a suspension of activated charcoal or water. The absorption of tolbutamide, calculated as the peak concentration and the area under the serum drug concentration-time curve during 0–48 h, was reduced by 90% by charcoal (p〈0.001). The absorption of valproate in these conditions was reduced on average by 65% (p〈0.01). In each subject charcoal had a greater effect on the absorption of tolbutamide than of valproate. According to these findings and preliminary in vitro studies on other sulphonylureas high doses of activated charcoal can be recommended for the preventing the absorption of sulphonylureas in acute intoxications. The poor aqueous solubility of these substances at the gastric pH probably delays their gastrointestinal absorption, so that they may be adsorbed on to charcoal even given several hours later.
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    Bioavailability and saturation of the presystemic metabolism of oral lorcainide therapy initiated in three different dose regimens (1983)
    Springer
    European journal of clinical pharmacology 24 (1983), S. 517-519 
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    ISSN: 1432-1041
    Keywords: lorcainide ; oral antiarrhythmic therapy ; nor-lorcainide ; first-pass metabolism ; kinetics ; alternative dosage ; regimens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The feasibility of giving a supplementary starting dose of the antiarrhythmic drug lorcainide, in order to minimalize the impact of the extensive, but saturable first-pass metabolism, was evaluated. Twenty-five adult patients were given 100 mg lorcainide tablets according to one of 3 different dosage schedules: Eight patients took one tablet at 0, 12 and 24h, 8 took 1 tablet at 0, 1, 12 and 24h and 9 took 1 tablet at 0, 2, 12 and 24h. Levels of lorcainide and its metabolite, nor-lorcainide, during treatment were determined by gas-liquid chromatography. The results show that giving a second tablet 1 or 2h after the first may produce faster saturation of the pre-systemic metabolism of lorcainide in the liver.
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    Lack of dose dependent kinetics of theophylline (1983)
    Springer
    European journal of clinical pharmacology 24 (1983), S. 525-527 
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    ISSN: 1432-1041
    Keywords: theophylline ; airway obstruction ; biotransformation ; kinetics ; oral dosage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Oral theophylline was given to 6 adults with airways obstruction. The initial dose was 125 mg daily and this was increased by 125 mg each week. The final total daily dose reached was determined by side effects and ranged from 500 mg to 1125 mg. At the end of each week and before the next dosage increment steady state, trough plasma theophylline concentrations were measured. For each individual and for the group as a whole there was a highly significant linear correlation between theophylline dose and trough plasma concentration. This indicates that for oral theophylline, in adults, dose-dependent kinetics do not play a significant role and dose may be adjusted without fear of a disproportionate rise in plasma concentration.
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    Pharmacokinetics of oral and rectal flurbiprofen in children (1984)
    Springer
    European journal of clinical pharmacology 27 (1984), S. 367-369 
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    ISSN: 1432-1041
    Keywords: flurbiprofen ; syrup ; suppository ; kinetics ; children ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Eight subjects, aged 6–12 years and weighing 18.8–36.7 kg, received single doses of flurbiprofen 50 or 75 mg (corresponding to 1.4–2.7 mg/kg) as syrup and suppository in a Latin square design. Half-life (2.7–3.2 h), elimination constant (0.22–0.26 h−1), area under the plasma level curve (72.4–77.3 µg·h·ml−1) and time to reach the concentration peak (1–0.75 h) were similar after the syrup and suppository. Flurbiprofen showed equivalent bioavailability after oral and rectal administration and the same pharmacokinetic profile was confirmed in children as observed in adults.
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    Amiodarone kinetics after single i.v. bolus and multiple dosing in healthy volunteers (1984)
    Springer
    European journal of clinical pharmacology 27 (1984), S. 491-494 
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    ISSN: 1432-1041
    Keywords: amiodarone ; kinetics ; volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary We studied three healthy volunteers after a single i.v. bolus of amiodarone, during 1 month of chronic oral dosing and after the discontinuation of the drug. Blood concentrations of amiodarone declined rapidly in a bi-exponential fashion after i.v. bolus. The terminal half-life ranged from 10 to 17 h; after discontinuation of chronic treatment the terminal half-lives were 8–21 days. The i.v. data, the trough levels during multiple dosing and the washout phase could be simultaneously fitted using a tri-exponential equation. The subjects were carefully monitored for cardiac and thyroid function. One subject had to stop taking amiodarone because of profound bradycardia. A reduction of serum TT3 and FT3 concentrations and an increase of serum rT3 and FT4 was found.
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    Extradural and parenteral pethidine as analgesia after total hip replacement: Effects and kinetics. A controlled clinical study (1986)
    Springer
    European journal of clinical pharmacology 29 (1986), S. 529-534 
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    ISSN: 1432-1041
    Keywords: pethidine ; epidural injections ; pain scores ; kinetics ; spinal cord
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Twenty-one patients who had undergone total hip replacement were randomly assigned to one of three groups in order to compare a single dose of 1 mg/kg of pethidine im (I) and 20 mg (II) or 60 mg of extradural pethidine (III) in a double-blind design. The degree of analgesia, the adverse effects, and the kinetics were studied for 18 h. Pain was monitored using a visual analogue scale (VAS). Supplementary doses of oxycodone if required were given no earlier than 0.75 h after pethidine. Plasma concentrations of pethidine were measured with gas chromatography mass spectrometry (GCMS). Hypoalgesia to pin prick test was evaluated. Low pain scores were observed in the extradural groups between 0.25 and 1.5 h after the dose. A significant difference in pain score compared with the im group was found after the higher extradural dose only between 0.5 and 1 h (p〈0.05). The area under the curve (AUC) of pain score versus time (0–18 h) was not significantly different between groups. The recorded adverse effects were minor in all three groups. The terminal half-lives and plasma clearances of pethidine, and the time to peak concentration were not different between the groups. Single patients in the extradural groups showed hypoalgesia to pin prick in parallel to the effect. The present study shows that extradural pethidine produces shortlived analgesia, in contrast to the long-lasting effect of morphine found in other studies.
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    Single and multiple dose pharmacokinetics of etizolam in healthy subjects (1991)
    Springer
    European journal of clinical pharmacology 40 (1991), S. 181-185 
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    ISSN: 1432-1041
    Keywords: Etizolam ; α-hydroxyetizolam ; healthy subjects ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of etizolam, a new thienodiazepine derivative, has been examined after single and multiple (0.5 mg tablet) (0.5 mg b.d for 1 week) oral therapeutic doses in healthy volunteers. The single-dose kinetic profile of etizolam suggested that absorption after oral dosage was reasonably rapid, the maximum plasma concentration (Cmax) being attained within 0.5–2 h in all subjects. The mean elimination half-life (t1/2) averaged 3.4 h. Consistent with this, steady-state concentration were rapidly achieved and accumulation was extremely limited. Predicted average plasma concentrations (Cp) did not differ significantly from those actually measured at steady-state, suggesting that the kinetics of etizolam was linear, at least at therapeutic doses. The mean wash-out t1/2 was comparable to the elimination t1/2 of the single dose, which means that the drug probably has no effect on hepatic microsomal enzymes and other kinetic variables after repeated dosing. At steady state plasma concentrations of the main metabolite, α-hydroxyetizolam, were higher and disappeared more slowly (mean t1/2 8.2 h) than those of the parent compound. Taken with the fact that in animals the metabolite shows almost the same potency of pharmacological action as etizolam, this suggests that it may contribute significantly to the clinical effects of the parent compound. Based on the kinetic characteristics of the parent drug and its metabolite, etizolam can be regarded as a short-acting benzodiazepine, with elimination kinetics between those of short-intermediate derivatives and ultra-rapidly eliminated benzodiazepines.
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    Bioavailability of controlled release carbamazepine estimated by mixed effect modelling (1993)
    Springer
    European journal of clinical pharmacology 44 (1993), S. 231-235 
    Details
    ISSN: 1432-1041
    Keywords: Carbamazepine ; kinetics ; population pharmacokinetics ; bioavailability ; controlled release ; non-linear model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The absorption properties of a conventional tablet of carbamazepine (T) and a controlled release form of carbamazepine (TCR) have been compared using a nonlinear mixed effect model (NONMEM). Plasma carbamazepine concentration data were obtained from an open, steady-state, crossover bioavailability study in which 494 measurements were obtained from 13 patients, with an equal number of samples per patient for each dosage form. The pharmacokinetic model used was a one-compartment open model with first-order absorption and elimination. The objective function was used as a measure of the goodness of fit of the model to the data. Body weight was an important determinant of carbamazepine clearance (CL) but not volume of distribution (V). Accounting for the interindividual variability in volume of distribution did not significantly influence the objective function. Including different rates of absorption (ka) for the two dosage forms resulted in a significant improvement in the objective function, as well as reducing the interindividual variability in the rate of absorption. Adding a parameter for relative bioavailability (f) of TCR improved the objective function statistically, but an unrealistic value for V was obtained, and the absorption and elimination rates appeared to be transposed in the classical “flip-flop” manner. Fixing V to the value obtained before introducing f did not change the objective function and permitted estimation of f without the confounding influence of excessive parameters. The final population parameter estimates (standard error of estimate) were: CL, 0.0522 (0.0019) l·h−1·kg−1; V, 63.7 (FIXED)l; kaT, 0.312 (0.064) h−1; kaTCR, 0.149 (0.016) h−1; f, 1.01 (0.0326); variance (additive) in CL, 0.291 (0.083) (l·h−1·kg−1)2; residual intrasubject error variance (additive), 0.572 (0.082) (mg·l−1)2. The 95% confidence interval of the extent of absorption (f) of 93.6%–107.4% was well within the generally accepted range of ±20%, while the rate of absorption of Tegretol CR was significantly slower than that of Tegretol, as expected for a controlled release product.
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    Sodium channel opening as a precursor to inactivation (1989)
    Springer
    European biophysics journal 16 (1989), S. 321-325 
    Details
    ISSN: 1432-1017
    Keywords: Sodium currents ; inactivation ; kinetics ; channel gating
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The time constant of the process producing the delay in Na inactivation development as determined by the two pulse method (τdelay) was extracted and compared to that of the slowest Na activation process τ3 for the I Na during the conditioning pulse of that same determination. τdelay and two pulse inactivation τc values were computer generated using a nonlinear least squares algorithm. τh and single pulse inactivation τh values were independently generated for each determination also with the aid of the computer using the same non-linear least squares algorithm. In one determination at 2 mV, τc was 4.68 and τdelay 0.494 ms while τh was 4.70 and τ3 0.491 ms for a τc/τh of 0.996 and a τdelay/τ3 of 1.006. Mean τdelay/τ3 from five determinations in four axons, both Cs and K perfused, and spanning a potential range of-27 to 2mV was 1.068. The precursor process to inactivation is channel opening. Some fraction of channels presumably inactivate via another route where prior channel opening is not required.
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    Influence of acetylsalicylic acid on the renal handling of a spironolactone metabolite in healthy subjects (1976)
    Springer
    European journal of clinical pharmacology 10 (1976), S. 43-48 
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    ISSN: 1432-1041
    Keywords: Spironolactone ; acetylsalicylic acid ; fludrocortisone ; kinetics ; pharmacology ; interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The influence of 600 mg acetylsalicylic acid (ASA) on the renal excretion and clearance of canrenone, the principal unconjugated metabolite of spironolactone, was examined in a double-blind crossover study in six healthy subjects. ASA significantly reduced the urinary excretion, and the fractional excretion, of canrenone between 4 — 6 hours after administration of 50 mg spironolactone. The pharmacological activity of spironolactone, assessed simultaneously by alterations in fludrocortisone-induced urinary electrolyte changes, was slightly but not significantly reduced. The reductions in urinary canrenone excretion correlated with changes in the urinary log 10 Na/K ratio. The results suggest that canrenone may be actively secreted at the proximal renal tubule, and that secretion is blocked by ASA or its conjugates. This is a possible mechanism for the pharmacological interaction between ASA and spironolactone which has been described previously.
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    Kinetics and efficacy of theophylline in the treatment of apnea in the premature newborn (1978)
    Springer
    European journal of clinical pharmacology 13 (1978), S. 203-207 
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    ISSN: 1432-1041
    Keywords: Theophylline ; kinetics ; apnea ; premature newborns ; developmental pharmacology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Aminophylline (theophylline-ethylenediamine) was administered to 27 premature newborns to prevent apneic spells. Of the 22 patients monitored for theophylline concentration, a therapeutic blood level was reached in 19 in 1–2 days, and 3 stayed below it. ‘Toxic’ blood levels (≥20 µg/ml) were reached in 3 cases, one of whom showed signs of toxicity. Theophylline treatment was not efficient in the prevention of apnea when a serious underlying disease was present. Theophylline blood half-life (mean : 27.0 h) and clearance (mean 12.9 ml/h/kg) confirmed the slow elimination pattern of the drug in the premature infant.
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    Differential kinetics of cinromide and two of its metabolites in epileptic patients (1981)
    Springer
    European journal of clinical pharmacology 21 (1981), S. 149-153 
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    ISSN: 1432-1041
    Keywords: cinromide ; epilepsy ; kinetics ; metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Cinromide is an experimental anticonvulsant currently in phase II testing. A single oral dose (900 mg) of cinromide was administered to 8 epileptic subjects on phenytoin therapy. Plasma samples drawn during the next 36 h were analyzed for cinromide and its amide and acid metabolites. The absorption rate of cinromide varied widely between subjects producing maximum cinromide concentrations between 0.5 and 2.5 h after the dose. The median elimination half lives of cinromide and the amide and acid metabolites were 0.73, 1.65, and 4.85 h respectively. The oral clearance of cinromide (median=135 l/h) suggests that it is subject to first pass metabolism. In all subjects the area under the curve (AUC) of acid metabolite (632 to 1777 µM/l) was greater than the AUC of amide metabolite (77 to 185 µM/l) which was greater than the AUC of cinromide (5 to 89 µM/l). Steady-state concentration ratios of metabolite to parent drug predicted from the AUC data were 3.8 for the amide and 35.8 for the acid metabolite. The amide metabolite is known to have anticonvulsant properties and, until the relative contributions of metabolites and parent drug to the efficacy of cinromide are resolved, the monitoring of metabolites as well as parent drug is imperative.
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    Kinetics of phenobarbital in normal subjects and epileptic patients (1982)
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    European journal of clinical pharmacology 23 (1982), S. 87-92 
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    ISSN: 1432-1041
    Keywords: phenobarbital ; epilepsy ; kinetics ; bioavailability ; epileptic patients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The kinetics of phenobarbital (PB) were evaluated in six normal subjects and six epileptic patients treated with phenytoin or carbamazepine. Each normal subject received three single doses of PB: PB-sodium 130 mg i.v. (IV), PB sodium 130 mg i.m. (IM), and PB acid 100 mg orally (PO), in random order at least one month apart. After IV PB distributive half-lives varied from 0.13 to 0.70 h, disposition half-lives were 75 to 126 h, steady state volume of distribution (Vss) was 0.54±0.03 l/kg, and clearance (CL) was 3.8±0.77 ml/h/kg. Absolute bioavailability of IM PB was 101±13%, of PO PB (corrected for dose) 100±11%. Peak serum PB concentrations were achieved from 2 to 8 h after IM administration, and from 0.5 to 4 h after PO administration. Epileptic patients exhibited similar PB kinetics: disposition half-lives were 77 to 128 h, Vss 0.61±0.05 l/kg, and Cl 3.9±0.76 ml/h/kg. Phenobarbital appears to represent an exception among antiepileptic drugs, in that pharmacokinetic data obtained in normals can reasonably be extrapolated to the epileptic population.
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    Influence of hyperthyroidism on the kinetics of methimazole, propranolol, metoprolol and atenolol (1982)
    Springer
    European journal of clinical pharmacology 21 (1982), S. 379-384 
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    ISSN: 1432-1041
    Keywords: hyperthyroidism ; propranolol ; methimazole ; metoprolol ; atenolol ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The kinetic profiles of oral methimazole 40mg, propranolol 80mg, metoprolol 100mg and atenolol 100mg were compared in hyperthyroid patients both during the hyper-and euthyroid states. For methimazole, neither the peak concentration (Cmax), the time to reach peak concentration (tmax), the elimination half-life (t1/2) nor the area under the curve (AUC) value was affected by the hyperthyroid state. For propranolol and metoprolol, which undergo extensive presystemic clearance, the AUC values were lower (p〈0.02) when the patients were hyperthyroid than when they had become euthyroid, but the t1/2's were not significantly altered. For atenolol, there were no significant kinetic differences between the hyperthyroid and euthyroid states. The findings are compatible with the assumption that hyperthyroidism does not affect the kinetics of methimazole or atenolol, but that it may enhance presystemic clearance of propranolol and metoprolol.
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    Pharmacokinetics in man of acebutolol and hydrochlorothiazide as single agents and in combination (1983)
    Springer
    European journal of clinical pharmacology 24 (1983), S. 801-806 
    Details
    ISSN: 1432-1041
    Keywords: acebutolol ; hydrochlorothiazide ; kinetics ; drug combination ; interaction ; diacetolol ; healthy subjects ; renal clearance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of acebutolol and hydrochlorothiazide (HCT) alone or in combination were studied in 12 healthy subjects in a cross over study. Acebutolol and diacetolol (the main metabolite) in plasma and urine were determined by HPLC and hydrochlorothiazide by GLC. The main pharmacokinetic parameters of acebutolol did not differ significantly: AUC 4492±272 µg l−1 h given alone versus 4118±354 µg l−1 h with HCT, half-life (7,69±0,32 h vs 8,10±0,72 h) and renal clearance (13,1±0,5 lh−1 vs 13,8±0,9 lh−1), respectively. There was no difference in diacetolol pharmacokinetics. HCT values were not significantly different: AUC 784±48 µg l−1 h given alone and 720±42 µg l−1 h with acebutolol, t1/2 (4,79±0,37 h vs 4,73±0,43 h). The renal clearance was slightly higher when HCT was given with acebutolol (26,2±2,6 vs 20,3±2,11 h−1,p〈0,05). This increase, observed during the first four hours, was probably due to competition between the drugs for binding to red blood cells.
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    Prizidilol, a combined vasodilatory and β-adrenoceptor blocking drug, in primary hypertension (1983)
    Springer
    European journal of clinical pharmacology 25 (1983), S. 179-186 
    Details
    ISSN: 1432-1041
    Keywords: prizidilol ; antihypertensive effect ; acute and long-term blood pressure control ; plasma renin activity ; acetylator phenotype ; antinuclear antibodies ; side effects ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary After an initial placebo period of four weeks 24 patients with primary hypertension were treated with prizidilol, a hydrazinopyridazine derivative with combined vasodilator and non-selective beta-adrenoceptor blocking actions, for a dose titration period of 14 weeks. Prizidilol 200 to 800 mg was given once daily to achieve a target supine diastolic blood pressure (BP)〈90 mmHg. Supine and standing BP recorded 24–27 h after drug intake decreased from 172±17/106±6 mmHg (mean±SD) and 167±18/111±8 mmHg, respectively, after placebo to 159±16/99±8 and 154±18/101±9 mmHg after active treatment for six weeks (mean dose 447 mg), and to 154±16/97±7 and 148±14/97±7 mmHg after treatment for 14 weeks (mean dose 687 mg/day). A slight reduction in HR was seen after treatment for six weeks and in plasma renin activity and urinary methoxycatecholamine excretion after treatment for 14 weeks. A sustained decrease in BP was observed for 10 h after prizidilol 800 mg (n=9), with a maximum antihypertensive effect (mean reduction in supine BP 33/18 mmHg) 2.5 h after dosing, which coincided with the mean peak plasma concentration. The plasma elimination half-life of the drug was 3.9 h (range 2.0–8.9 h). Changing to a twice daily regimen in 17 patients (mean daily dose 748 mg at six months) did not produce any further reduction in the BP (recorded 12–15 h after dosing) as compared to the once daily regimen at 14 weeks. During treatment for up to 24 months, 16 patients did not achieve satisfactory BP control. Eight of them were withdrawn and eight received additional treatment with bendroflumethiazide (2.5–5 mg/day). In 7 of the latter satisfactory BP control was achieved. Side effects were few. Dizziness and tiredness occurred in four patients 2–5 h after prizidilol 600–800 mg once daily. These symptoms partly subsided when the subjects changed to a twice daily regimen. No ocular side-effects were found. Before treatment 13 out of 24 patients had a low titre of IgM antinuclear antibodies (ANA) and one patient also a low titre of IgG ANA. During treatment the frequency of patients with positive ANA-titres became higher, and after treatment for 12 months (n=17) 15 patients had positive IgM and seven patients positive IgG ANA-titres. However, the titres were low and no patient showed a clinical lupus erythematosus syndrome. There was no relation between acetylator phenotype of the patient and acute or longterm effecton BP, pharmacokinetics of the drug or the development of a raised ANA-titre.
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    Glibenclamide pharmacokinetics in acarbose-treated type 2 diabetics (1984)
    Springer
    European journal of clinical pharmacology 27 (1984), S. 233-236 
    Details
    ISSN: 1432-1041
    Keywords: glibenclamide ; acarbose ; kinetics ; alpha-glucosidase inhibitor ; blood glucose control ; plasma insulin ; Type 2 diabetes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A single dose of glibenclamide 5 mg was administered to six Type 2 diabetics, randomly treated for 7 days either with acarbose (3×100 mg daily) or with placebo. The serum concentration of the drug was measured for 10 h. Peak concentrations, times-to-peak concentration, elimination half-lives and the extent of bioavailability of the drug were not significantly modified by acarbose. The combined administration of glibenclamide and acarbose resulted in a modest improvement in the blood glucose profile after breakfast and lunch, together with a significant diminution in plasma insulin. Thus, acarbose appears a useful additional treatment for Type 2 diabetics already receiving sulphonylurea derivatives.
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    Kinetic studies on rifampicin (1972)
    Springer
    European journal of clinical pharmacology 5 (1972), S. 111-115 
    Details
    ISSN: 1432-1041
    Keywords: Rifampicin ; kinetics ; multicompartmental analysis ; simultaneous serum urine and bile assessment ; one week treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary To aid interpretation of the fall in the serum concentrations of rifampicin observed in the early phase of continuous treatment, the distribution of the antibiotic was assessed simultaneously in the serum, bile, and urine of patients treated for one week. Transfer constants between these compartments were calculated on the 1st and 7th day of treatment by multicompartmental kinetic analysis. — The results obtained suggest that the decrease in serum concentrations is due to enhanced biliary excretion; no significant change was observed in the amount of antibiotic excreted in the urine. The increased capacity of the liver to excrete rifampicin in bile might result from enzyme induction by the antibiotic in hepatocytes.
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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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    Structure-property relationships in thin films and membranes (1995)
    Springer
    Journal of sol gel science and technology 4 (1995), S. 117-133 
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    ISSN: 1573-4846
    Keywords: kinetics ; precursor chemistry ; silica ; permeability ; microstructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The molecular-scale species distributions and intermediate-scale structure of silicate sols influence the microstructures of the corresponding thin films prepared by dip-coating. Using multi-step hydrolysis procedures, we find that, depending on the sequence and timing of the successive steps, the species distributions (determined by 29Si NMR) and intermediate scale structure (determined by SAXS) can change remarkably for sols prepared with the same nominal composition. During film formation, these kinetic effects cause differences in the efficiency of packing of the silicate species, leading to thin film structures with different porosities.
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    FTIR Spectroscopy, SAXS and Electrical Conductivity Studies of the Hydrolysis and Condensation of Zirconium and Titanium Alkoxides (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 41-47 
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    ISSN: 1573-4846
    Keywords: zirconium butoxide ; titanium butoxide ; kinetics ; hydrolysis ; condensation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A continuous flowing-rapid mixing technique was combined with FTIR, SAXS and electrical conductivity to study the early stages of polymer formation and growth during the acid-catalyzed hydrolysis and condensation of titanium and zirconium alkoxides. Reaction times as short as 80 milliseconds were investigated. FTIR spectroscopy was used to monitor the water and M–OR concentrations during the reaction. Hydrolysis of ∼25–50% of the alkoxy groups was facile. The FTIR and SAXS data showed that condensation was also very rapid. The activity and mobility of the ions in the solution were monitored by electrical conductivity measurements. The decrease in the normalized solution conductivity during the reaction correlated with the loss of [M–OR]. Furthermore, the radius of gyration of the growing polymers increased rapidly in regimes where the conductivity and [M–OR] decreased fastest. This finding suggests that the mobility of some of the charge carrying species decreases because of the growth in size of the polymers.
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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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    Kinetics of Solid State Reactions With Fractal Reagent (1998)
    Springer
    Journal of materials synthesis and processing 6 (1998), S. 305-309 
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    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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    High-temperature oxidation kinetics of Cu-Si alloys containing up to 4.75 wt.% Si in $$p_{{\text{O}}_{\text{2}} } $$ =0.01 atm and pure CO2 (1978)
    Springer
    Oxidation of metals 12 (1978), S. 323-329 
    Details
    ISSN: 1573-4889
    Keywords: Cu-Si alloys ; oxidation ; kinetics ; silica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of Cu-Si alloys (containing up to 4.75 wt. % Si) in $${\text{p}}_{O_2 } $$ =0.01 atm from 800 to 1000°C has been investigated using thermogravimetry and other techniques. A 0.04% Si alloy followed a parabolic oxidation law with a rate similar to that of pure Cu. As the Si concentration increased the rate decreased and became irregular owing to SiO2 particles or flakes at the alloy-scale interface. It is considered that sintering of SiO2 particles and rupture of the sinter because of contraction during sintering are responsible for the irregular kinetics. A SiO2 layer forms directly on the 4.75% Si alloy which oxidizes uniformly. The SiO2 was always amorphous. In pure CO2 a similar pattern of amorphous SiO2 particles, flakes, and layers occurs.
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    Modeling of the Phase Transformation Induced by Ball Milling in Anatase TiO2 (2000)
    Springer
    Journal of materials synthesis and processing 8 (2000), S. 139-144 
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    ISSN: 1573-4870
    Keywords: TiO2 ; phase transformations ; mechanical alloying ; kinetics ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A high-pressure and high-temperature phase of TiO2 : TiO2 II is formed transiently during room-temperature high-energy ball milling of anatase TiO2 : TiO2 anatase → TiO2 II → TiO2 rutile. Rutile is the only phase present after prolonged ball milling. The present paper focuses on the influences of physical and chemical processing conditions on the transformation kinetics. The effects of two milling parameters on the kinetics of phase transformation of anatase TiO2 were investigated: the nature of milling tools and the powder-to-ball weight ratio R. Granulometric characterizations and TEM observations have demonstrated that the transformation of TiO2 anatase into TiO2 II occurs without fracturing of particles and that TiO2 II nanograins form at the surface of anatase particles. The parameter R affects only the transformation rate. For a given R, the transformation rate is the largest with alumina grinding tools, intermediate with zirconia tools, and the smallest with steel tools. The parameters involved in current models of the mechanical alloying process do not suffice to explain the differences in transformation rates observed here. A parameter, which takes into account the influence of the mechanical properties of grinding materials, is considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011351807629
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    Relating Single-Impact Events to Macrokinetic Features in Mechanical Alloying Processes (2000)
    Springer
    Journal of materials synthesis and processing 8 (2000), S. 271-277 
    Details
    ISSN: 1573-4870
    Keywords: Comminution ; kinetics ; mechanical alloying ; phase transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract It has been shown that structural evolution occurring in powder mixtures subjected to mechanical treatment by milling follow well-defined conversion trends as a function of milling time. Sigmoidal curves were observed in the case of the mechanical alloying of transition metal mixtures, whereas a simpler kinetic course with a progressively decreasing transformation rate was found to characterize the disordering process of intermetallic equilibrium compounds by mechanical milling. Under the stipulation that collisions are the dominant energy transfer events, a kinetic model is developed to relate the observed macrokinetic features to the discrete powder fractions, which transform at each impact. Because of its intrinsic qualities, the milling process was regarded as discrete processing. A statistical approach was followed to work out a set of differential equations, solutions of which provide a sound description of the transformation kinetics in terms of conventional rate expressions. The model allows one to reproduce the different kinetic behaviors by means of a single, unifying mathematical formalism. Furthermore, quantifying the structural evolution rate by suitable kinetic constants permits the exploration of the reactive behavior of a system treated under different milling regimes or to compare, on an absolute basis, different systems processed under similar conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011382008963
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    Dissolution kinetics of small amounts of oxygen in tantalum alloy T-111 and internal oxide displacement reactions during annealing (1976)
    Springer
    Oxidation of metals 10 (1976), S. 291-309 
    Details
    ISSN: 1573-4889
    Keywords: tantalum alloy ; oxygen ; dissolution ; kinetics ; oxides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Oxygen was added to T-111 (Ta-8W-2Hf, wt.%) at 820 and 990°C at an oxygen pressure of about 3×10−4 Torr (4×10−2N/m2). The technique employed permitted predetermined and reproducible doping of T-111 up to 3.0 at% oxygen. Based on the temperature dependence of the doping reaction, it is concluded that the initial rates of oxygen pickup are probably controlled by solution of oxygen into the T-111 lattice. Although hafnium oxides are more stable than those of tantalum or tungsten, analyses of extracted residues indicate that the latter oxides predominate in the as-doped specimens, presumably because of the higher concentrations of tantalum and tungsten in the alloy. However, high-temperature annealing promotes gettering of dissolved oxygen and of other oxides to form hafnium oxides. Small amounts of tantalum and tungsten oxides were still present after high-temperature annealing. Tungsten oxide (WO3) volatilizes slightly from the surface of T-111 at 990°C. The vaporization of WO3 has no apparent affect on the doping reaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00612028
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    Influence on the oxidation kinetics of metals by control of the structure of oxide scales (1976)
    Springer
    Oxidation of metals 10 (1976), S. 361-376 
    Details
    ISSN: 1573-4889
    Keywords: metals ; scale structure ; epitaxy ; kinetics ; diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An explanation of the deviation from the parabolic law is the treatment which considers both shortcircuit and lattice diffusion in the oxide scale. In this study we examine how the oxidation kinetics are influenced by changing the structure of the scale of copper oxide in order to confirm the role of short-circuit diffusion in determining the oxidation rate. In addition we explain the oxidation kinetics of copper and nickel by using a model of the scale structure which includes recrystallization and grain growth. Results are as follows: (1) The nucleation and growth behavior of oxide have a direct effect on the structure and in turn the oxidation kinetics due to short-circuit diffusion. (2) A modified treatment is valid in the region where volume diffusion and short-circuit diffusion play an important role in which it is necessary to consider the scale structure such as the grain size distribution and the boundary width. (3) When recrystallization takes place it is necessary to consider the model of a two-layered scale structure which is different in properties and morphology. (4) In this region the rate curves are S-shaped when oxide recrystallization takes place and exhibit a transition from a parabolic to an nth-power relationship (n〉2) when grain growth takes place.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00612048
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    High-temperature oxidation of titanium silicide coatings on titanium (1982)
    Springer
    Oxidation of metals 17 (1982), S. 43-54 
    Details
    ISSN: 1573-4889
    Keywords: Coatings ; oxidation ; titanium silicide ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Coatings of Ti 5Si3 on titanium have been prepared by means of decomposition of silane SiH4 on heated titanium ribbons. Oxidation of the coated titanium specimens was much slower than that of the noncoated ones. Gravimetric and morphological experiments allowed to propose a mechanism describing the oxidation process.
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    URL: http://dx.doi.org/10.1007/BF00606192
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    Oxidation of Ti-1Si and Ti-5Si alloys (1982)
    Springer
    Oxidation of metals 17 (1982), S. 359-369 
    Details
    ISSN: 1573-4889
    Keywords: Oxidation ; microhardness ; oxide thickness ; kinetics ; oxygen partition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Oxidation kinetics of Ti-1 wt. % Si and Ti-5 wt. % Si alloys in either pure oxygen or air under a pressure of 0.93 bar and in the temperature range of 1171–1473 K are reported. For the exposure period investigated (up to 12 h) both alloys oxidized slower than pure Ti. The amount of oxygen dissolved in the Ti-1 wt. % Si alloy has been calculated. X-ray diffraction analyses indicate that the oxide scale is mainly TiO 2 ,except for the Ti-5 wt. % Si alloy oxidized at 1473 K where some evidence of SiO 2 was obtained. Hardness profiles were taken across the Ti-1 wt. % Si alloy matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00742117
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    Mechanism of internal oxidation in silver alloys (1984)
    Springer
    Oxidation of metals 21 (1984), S. 21-37 
    Details
    ISSN: 1573-4889
    Keywords: internal oxidation ; kinetics ; alloy ; silver ; precipitation ; coalescence ; ageing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The internal oxidation mechanism in silver alloys was studied by residual resistivity, gravimetric, and calorimetric measurements, and by transmission electron microscopy. If the flux, of oxygen atoms is very large with respect to the oxide formation, the mechanism of internal oxidation includes two stages. The first one is the fixation of oxygen in the form of oxidized elementary species, including only one solute atom. These species are stable and keep a certain mobility. The second one is the coalescence process of these elementary species with the formation of the first clusters. When the flux of oxygen atoms is slowed down, the oxide formation mechanisms are more complicated. The initially formed species can include more than one solute atom because of their diffusion. The two stages are not separate.
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    URL: http://dx.doi.org/10.1007/BF00659465
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    Correlation between the oxidation mechanism of titanium under a pure oxygen atmosphere, morphology of the oxide scale, and diffusional phenomena (1980)
    Springer
    Oxidation of metals 14 (1980), S. 249-261 
    Details
    ISSN: 1573-4889
    Keywords: titanium ; oxidation ; oxide scale ; solid state diffusion ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation behavior of titanium was studied over the temperature range of 600 to 800°C in a pure oxygen atmosphere. A parabolic kinetics period is made up of a succession of short parts whose weight gain is nearly constant and whose beginning is characterized by an alteration of the oxidation rate. The kinetics curve is closely correlated with the morphology of the oxide scale which contains several layers separated by short cracks. These cracks decrease the diffusional flows of oxygen and titanium and alter the oxidation rate. A parabolic-linear kinetics transition is attributed to the formation of a continuous crack between the oxide scale and the matrix. The oxide scale then forms a porous barrier of constant thickness which induces a linear rate law due to the steady-state oxygen diffusion. Titanium cannot diffuse across the continuous crack. During the linear kinetics period several layers of constant thickness, separated by a continuous crack, spread out.
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    URL: http://dx.doi.org/10.1007/BF00604567
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    Comparison of the kinetics and morphologic properties of titanium, Ti-1.5Ni and Ti-2.5Cu during oxidation in pure oxygen between 600 and 820°C (1980)
    Springer
    Oxidation of metals 14 (1980), S. 471-498 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; titanium ; Ti-Ni alloy ; Ti-Cu alloy ; kinetics ; oxide scale ; solid-state diffusion
    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 and morphologic oxidation properties of titanium, Ti-1.5Ni and Ti-2.5Cu were compared. Titanium and Ti-1.5Ni have a similar behavior, concerning the kinetics and the oxide micro structure. Copper additions decrease the oxidation rate of titanium. The oxide scales formed on Ti-Cu are thinner and less cracked than those obtained on Ti or Ti-1.5Ni. Copper is found in the oxide scale of Ti-Cu, whereas nickel is not found in the oxide scale of Ti-Ni. The oxidation of titanium and its alloys is controlled chiefly by diffusional phenomena in the oxide scale. Thus the alterations of the oxide scale structure and the slower oxidation rate of Ti-2.5Cu can be attributed to the copper which diffuses towards the gas-oxide interface.
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    URL: http://dx.doi.org/10.1007/BF00603475
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    Sulfidation behavior of Ni-Cr-Mo alloys at 700°C (1984)
    Springer
    Oxidation of metals 22 (1984), S. 45-57 
    Details
    ISSN: 1573-4889
    Keywords: Ni-Cr-Mo alloys ; sulfidation ; scale structures ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effect of molybdenum additions 5, 10, 15, and 20 wt. %, on the sulfidation behavior of Ni-20Cr, and the effect of chromium additions, 5, 10, 15, and 20 wt.%, on the sulfidation of Ni-20Mo were studied in pure sulfur vapor at 700°C. In general, the alloys followed a linear or near-linear rate law, the sulfidation rate of Ni-20Mo being slightly less than that of Ni-20Cr. The alloys having the lowest ternary addition, e.g., Ni-Cr-5Mo and Ni-20Mo-5Cr. exhibited the most rapid reaction rates. The highest alloying additions of 20 wt.% had no appreciable benefit on reaction rates. Scale structures were complex but generally consisted of several layers. The outer layer was always NiS1.03, although both binaries formed Ni3S2 within the NiS1.03. An inner layer of Cr3S4 existed in which there was considerable dissolved molybdenum. A thin, intermediate layer of Cr2S3 generally formed between the Cr3S4 and the outer nickel sulfide. An innermost layer of MoS2 formed on all alloys containing more than 10 wt. % Mo, and a second phase of Mo2S3 formed within the MoS2 on Ni-20Mo. Although the scales changed with alloy composition, no significant changes in reaction rate were observed. Notable differences in both scale structure and reaction kinetics between this study and previous studies were apparent. The differences and possible reaction mechanisms are discussed.
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    URL: http://dx.doi.org/10.1007/BF00659248
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    Effect of yttrium on the sulfidation behavior of Ni-Cr-Al alloys at 700°C (1986)
    Springer
    Oxidation of metals 25 (1986), S. 1-28 
    Details
    ISSN: 1573-4889
    Keywords: sulfidation ; yttrium ; duplex-sulfide scales ; lamellar sulfides ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The sulfidation of Ni-10Cr-5Al, Ni-20Cr-5Al, and Ni-50Cr-5Al, and of the same alloys containing 1% Y, was studied in 0.1 atm sulfur vapor at 700°C. The sulfidation process followed linear kinetics for all the alloys except Ni-50Cr-5Al-1Y, and possibly Ni-50Cr-5Al, which followed the parabolic law. The reaction rates decreased with increasing chromium content in alloys without yttrium, and the addition of yttrium reduced the rates by at least a factor of two for the alloys containing 10 and 20% Cr and by an order of magnitude for Ni-50Cr-5Al. Alloys containing 10 and 20% Cr (with and without yttrium) formed duplex scales consisting of an outer layer of NiS1.03 and an inner lamellar layer of a very fine mixture of Cr2S3 and A12O3 in a matrix of NiS1.03. The two alloys containing 50% Cr formed only a compact layer of Cr2S3, which was brittle and spalled during cooling. The lamellae in the duplex scales were parallel to the specimen surface and bent around corners. The lamellae were thicker than those on Ni-Al binary alloys. The lamellae were also thicker in scales on the 20% Cr alloy than on the 10% Cr alloy. The presence of yttrium refined the lamellae and increased the lamellae density near the scale/metal interface in the 10% alloy, but in the 20% Cr alloy the lammellae were thicker and more closely spaced. Platinum markers were found in the inner portion of the exterior NiS1.03 layer close to the lamellar zone. A counter-current diffusion mechanism is proposed involving outward cation diffusion and inward sulfur diffusion, although diffusion was not rate controlling for alloys containing 10 and 20% Cr. Auger analysis of scales formed on Ni-50Cr-1Y showed an even distribution of yttrium throughout the layer of Cr2S3, suggesting that some yttrium dissolved in the sulfide. The reduced sulfidation rate of samples containing yttrium is explained by the possible dissolution of yttrium as a donor. The presence of Y4+ would then decrease the concentration of interstitial chromium ions in the N-type layer of Cr2S3, which would decrease the reaction rate.
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    URL: http://dx.doi.org/10.1007/BF00807994
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    Molten carbonate-induced hot corrosion of nickel (1989)
    Springer
    Oxidation of metals 32 (1989), S. 225-240 
    Details
    ISSN: 1573-4889
    Keywords: Hot corrosion ; nickel ; TGA ; kinetics ; mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The accelerated oxidation of pure nickel in the presence of a molten carbonate mixture has been studied in O2 and CO2-containing atmospheres. The oxidation rate of nickel with carbonate coatings was at least four orders of magnitude faster than that without salt coatings. The extent of oxidation, in terms of unit area weight gain, depended on both the amount of carbonate mixture coatings and the gas atmosphere. The unit area weight gain due to oxidation increased with increasing amounts of salt coatings up to a certain value. These observations suggest that the termination of nickel oxidation results from the exhaustion of either the salt coatings or metallic nickel. Porous and particulate oxide products were observed from scanning electron microscopic (SEM) examinations. The energy-dispersive analysis of x-rays (EDAX) shows that no salt remains on the specimen surface after the oxidation experiment.
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    URL: http://dx.doi.org/10.1007/BF00664800
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    High-temperature oxidation of titanium-hydride powders (1990)
    Springer
    Oxidation of metals 33 (1990), S. 177-189 
    Details
    ISSN: 1573-4889
    Keywords: kinetics ; oxidation ; titanium hydride ; rutile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation kinetics of titanium-hydride powders were studied in the temperature range of 298–1378 K in air at atmospheric pressure. DTA, DSC, X-ray analysis, and scanning electron microscopy were used. Oxidation was found to take place by TiHxOy oxyhydride phases formation. The oxidation reaction rate at temperatures above 870 K was limited by diffusion of oxygen atoms through a rutile scale formed on the surface. The activation energy and preexponential values of the Arrhenius equation for different interaction stages as well as transformation enthalpies were calculated.
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    URL: http://dx.doi.org/10.1007/BF00665675
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    Corrosion in SO2 of chromium and manganese at high temperature (1990)
    Springer
    Oxidation of metals 33 (1990), S. 279-299 
    Details
    ISSN: 1573-4889
    Keywords: corrosion SO2 ; chromium ; manganese ; kinetics ; scale analysis ; phase diagram stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The corrosion of chromium and manganese by pure SO2 has been investigated in the temperature range 890–1350 K at SO2 pressure from 0.01–0.5 atm. Both metals oxidize according to a parabolic rate law, and the scales consist of an inner region containing a mixture of oxide and sulfide (Cr2O3+ CrS or MnO and MnS) and an outer region of oxide (Cr2O3 or MnO). These two metals have similar thermodynamic behavior, and the main mechanism of reaction is considered to be the direct reaction of the metal with SO2. The results also indicate that in the absence of trace amounts of oxygen, and at sufficiently low temperature (〈950 K), the formation of Mn3O4 does not occur only if a complete description of the atmosphere generated by a SO2-O2-S2 mixture was considered.
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    URL: http://dx.doi.org/10.1007/BF00667418
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    Oxide particles in Ag-Mg alloys formed by internal oxidation (1992)
    Springer
    Oxidation of metals 37 (1992), S. 65-80 
    Details
    ISSN: 1573-4889
    Keywords: internal oxidation ; kinetics ; alloys ; silver ; oxide particles ; coalescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Gravimetric measurements at low temperatures (〈600°C) and for dilute Ag-Mg alloys have given further information about the mechanism of oxide formation. This investigation shows that the fixation rate of oxygen is very high, which assumes the existence of species in an oxidized form, including one or two magnesium atoms called “elementary species” and denoted as MgO* and Mg2O*. When there are no free magnesium atoms, there is a coalescence process with the fixation of oxygen atoms or MgO* and Mg2O*: this process leads to the formation of the first “clusters” including an oxygen excess. At low temperatures, the thermal fluctuations do not permit significant changes. There is no significant increase in cluster size, but a rearrangement of these clusters toward a compact structure with the release of excess oxygen. Their size is less than 1 nm.
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    Morphological characteristics of the oxidation of niobium II: The role of stresses on high-temperature morphologies (1994)
    Springer
    Oxidation of metals 41 (1994), S. 235-250 
    Details
    ISSN: 1573-4889
    Keywords: niobium ; oxidation ; morphology ; kinetics ; stresses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of niobium at high temperature (900°C) leads to reaction products with “exotic” morphologies. Morphological and kinetics analysis have been undertaken with Nb platelets. A growth mechanism of the oxide at the edges of the platelet is proposed.
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    URL: http://dx.doi.org/10.1007/BF01080782
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    High-temperature oxidation of tantalum of different purity (1995)
    Springer
    Oxidation of metals 43 (1995), S. 509-526 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; kinetics ; tantalum ; oxide ; suboxide ; impurities ; diffusion
    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, structural aspects, and phase morphologies were studied for tantalum oxidation in air from 600 to 1000°C for samples of different purity (99.15%, 99.76%, and 99.95% Ta). Regardless of purity, tantalum oxidation in the temperature range of 600–800°C as a rule is governed by a linear rate law. From 900 to 1000°C the initial-stage oxidation is governed by the parabolic rate law, which changes to the linear rate law with time. TGA, XRD, SEM, and AES methods were used. The, effect of purity on tantalum oxidation was shown to be determined by the mechanism of intermediate-oxide formation. They are TaO z (Ta2O) at 600–800°C and TaO at 900–1000°C. The final product of oxidation was β-Ta2O5.
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    Sulfidation behavior of a ferritic commercial alloy in different sulfidizing environments at high temperature (1995)
    Springer
    Oxidation of metals 43 (1995), S. 543-560 
    Details
    ISSN: 1573-4889
    Keywords: stainless steel ; sulfidation ; hydrogen sulfide ; sulfur vapor ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The sulfidizing behavior of Fe−22Cr−4Al−0.15Zr (wt.%) was studied in two atmospheres: S2 vapor over the range 4.4–25.4 Pa and H2−H2S mixtures corresponding to aP S 2 range 0.2–1.297 Pa in the temperature range 973–1373 K. It was found that the constitution of the gaseous phase is of great importance on the corrosion kinetics and the morphology of the corrosion products. Furthermore, a stratification phenomenon during scale growth was observed during the initial sulfidation stage in H2−H2S mixtures containing a sufficiently high H2S partial pressure. This behavior was not observed during tests in puresulfur vapor.
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    Role of interface structure and interfacial defects in oxide scale growth (1995)
    Springer
    Oxidation of metals 44 (1995), S. 63-79 
    Details
    ISSN: 1573-4889
    Keywords: scale growth ; oxidation mechanism ; kinetics ; scale adherence ; reactive element effect ; intertacial segregation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Recent studies of the structure and dynamics of solid-solid interfaces have provided some understanding about the role of the scale-metal interface in the growth of reaction product scales on pure metals. The action of interfacial defects (misfit dislocations, misorientation dislocations and disconnections) in the creation and annihilation of the point defects suporting the diffusional growth of scales is considered. Anion point defects (vacancies/interstitials) supporting scale growth by anion diffusion are annihilated/created by the climb of misorientation dislocations or disconnections in the scale at the interface. For scale growth by cation diffusion, cation point defects (vacancies/interstitials) can be annihilated/created by the climb of interfacial misfit or misorientation dislocations in the metal. Because of their necessarily high density, in most cases, the dominant climb of misfit dislocations would be favored. The blocking of interfacial reaction steps can be a means to retard the scaling kinetics and to alter the fundamental scaling mode. For instance, the interfacial segregation of large reactive element ions can pin the interface dislocations, an action which poisons the usual interfacial reaction step. Such considerations are consistent with the well-known phenomena ascribed to the reactive element effect (REE).
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    High-Temperature Oxidation Behavior of the Co-Base Superalloy DZ40M in Air (2000)
    Springer
    Oxidation of metals 53 (2000), S. 351-360 
    Details
    ISSN: 1573-4889
    Keywords: Co-base superalloy ; high-temperature oxidation ; kinetics ; structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation behavior of the Co-base superalloy DZ40M was studied in air at900–1100°C for times of up to 2000 hr. The results indicated thatthis alloy can grow a protective oxide scale at 900 and 1000°C duringisothermal oxidation, but not at 1100°C because of serious cracking andspalling of the oxide scales. Moreover, an internal-precipitate zone formedin the subsurface region of the alloy at all temperatures and times. Theprecipitates were rich in Cr in the vicinity of the alloy–scaleinterface and rich in Al deep in the alloy. The internal-precipitatemorphology changed from a granular to needlelike shape with increasingoxidation temperature.
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    URL: http://dx.doi.org/10.1023/A:1004597405809
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    The oxidation behavior of a Zr-0.5Y alloy (1975)
    Springer
    Oxidation of metals 9 (1975), S. 357-365 
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    ISSN: 1573-4889
    Keywords: kinetics ; zirconia ; defect structure ; ionic conductivity ; yttria dopant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A Zr-0.5 Y alloy was found to oxidize about 6 times faster than pure zirconium over the temperature range of 400 to 565°C. The activation energies were nearly identical (∼32 kcal/mole). The activation energies correspond to grain boundary diffusion of oxygen through the scale. The higher oxidation rate of the alloy was attributed to a higher anion vacancy concentration and the assumption that diffusion sites in the lattice and boundaries were in local equilibrium. Measurements on yttria-doped zirconia showed that ionic conductivity was increased markedly by yttrium and extended over a wide range of oxygen pressure. The defect structure of the doped oxide was changed to one of oxygen vacancies, even at the high end of the oxygen pressure range, 10−8 to 0.2 atm, over which pure ziconia contains oxygen interstitials. The doped oxide was found to be extrinsic over the entire range of oxygen pressure and, although ionic conductivity predominated, electronic conductivity was still appreciable. The electronic conductivity, however, was still sufficiently high so that electron transport was not rate-controlling in the predominantly ionic-conducting scale.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00613535
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  • 89
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    A rapid method for determining parabolic rate constants of metal oxidation as a function of temperature and oxidant pressure (1975)
    Springer
    Oxidation of metals 9 (1975), S. 441-450 
    Details
    ISSN: 1573-4889
    Keywords: kinetics ; cobalt and nickel oxidation ; parabolic rate constant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A new fast method is proposed for the determination of parabolic rate constants of metal oxidation as a function of pressure and temperature. The method consists of determining rate constants by oxidation of a single metal sample in a continuous manner, periodically changing the oxidant pressure or temperature. This method eliminates a number of errors inherent in the classical method which involves the use of a new metal specimen in each experiment and it further shortens the time of evaluating the functions k p '' = f (p, T). The method is particularly suitable for the determination of rate constants of slow processes. To verify the proposed method measurements of the kinetics of oxidation of cobalt and nickel at different oxygen pressures over the temperature range 1000–1300° C were carried out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00611692
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  • 90
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    Effect of oxide grain structure on the high-temperature oxidation of Cr (1975)
    Springer
    Oxidation of metals 9 (1975), S. 459-472 
    Details
    ISSN: 1573-4889
    Keywords: Cr ; oxidation ; kinetics ; Cr2O3 grain size ; short-circuit diffusion ; surface ; preparation ; Fe-Cr
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Cr was oxidized in 1 aim O2 at 980, 1090, and 1200°C. ElectropolishedCr and some orientations of etched Cr oxidize rapidly and develop compressive stress in the growing Cr2O3; other orientations oxidize slowly, apparently free of stress. SEM examination of fracture sections shows that the thick oxide is polycrystalline whereas the thin oxide on etched Cr is monocrystalline. It is deduced that the monocrystalline oxide grows by lattice diffusion of cations outward, and the polycrystalline layer by the two-way transport of cation diffusion outward and anion diffusion inward along oxide grain boundaries. The consequent formation of oxide within the body of the polycrystalline layer generates compressive stress and leads to wrinkling by plastic deformation. The activation energy for oxidation of Cr by cation lattice transport is 58 kcal/mole. Polycrystalline Cr2O3 forms on Fe-26Cr alloy, whether electropolished or etched; oxidation is accordingly rapid and accompanied by compressive stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00611694
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  • 91
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    Calculations of parabolic rate constants for metal oxidation (1974)
    Springer
    Oxidation of metals 8 (1974), S. 379-391 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; sulfidation ; kinetics ; parabolic rate law
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The conditions necessary to determine the oxidation kinetics of metals and alloys are discussed quantitatively, and a new method of calculating the rational rate constants was suggested. It was shown that the size and the shape of a metal sample has an effect on the kinetics of oxidation. Further, it was established that the values of the parabolic rate constants of corrosion, calculated from the empirical Pilling and Bedworth equation, contain a serious systematic error, if changes in the metallic core surface area during the oxidation process are neglected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00603388
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  • 92
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    Kinetics of the oxidation of ilmenite (1975)
    Springer
    Oxidation of metals 9 (1975), S. 99-116 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; kinetics ; ilmenite ; rutile ; pseudobrookite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of ilmenite (FeTiO3) in air and dry oxygen was investigated over the temperature interval 600 to 970°C. Dense platelets of ilmenite crystals as well as powder samples of ilmenite were oxidized. The weight data were recorded employing a thermobalance. The oxidation kinetics of ilmenite platelets were parabolic except for the initial stages during which logarithmic kinetics were observed. For powder samples the logarithmic rate law was followed primarily. The logarithmic rate law was attributed to free penetration of oxygen through cracks and short-circuit paths. The activation energies associated with the logarithmic rate law were nearly one-half of those obtained from parabolic oxidation. The growth morphology of the products of oxidation of ilmenite was observed with a scanning electron microscope. The effect of growth morphology on the kinetics is discussed, and a probable reaction mechanism is suggested for the oxidation of ilmenite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00613496
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  • 93
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008644405473
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  • 94
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    A two-component, non-aqueous route to silica gel (1994)
    Springer
    Journal of sol gel science and technology 2 (1994), S. 35-41 
    Details
    ISSN: 1573-4846
    Keywords: carboxylic acids ; mechanism ; kinetics ; ultrafine porosity ; CO2 adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new means for generating silica gel has been developed. Simple two component systems comprising tetraalkoxysilanes and strong carboxylic acids such as formic acid can react rapidly to give transparent monolithic gels. The acid serves as solvent, water source, and catalyst for both hydrolysis and condensation. Water need not be present as an initial reactant; it is generated in situ during the reaction. The gelation reaction is at least two orders of magnitude faster than those conducted in conventional acid-catalyzed aqueous systems at comparable pH*. Kinetic evidence indicates a lowering of the activation energy of condensation reactions, believed to be associated with reaction of silyl carboxylates and silanol groups. Physical properties of the dry gels such as bulk density more closely resemble conventional acid-catalyzed gels than those associated with other rapidly gelling systems. Dry gels often exhibit porosity so fine that nitrogen (at 77°K) is not absorbed at significant rates. Independent evidence of porosity arises from comparison of skeletal and bulk densities, sample immersion in water and adsorption isotherms of CO2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00486210
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  • 95
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    FTIR spectroscopy, SAXS and electrical conductivity studies of the hydrolysis and condensation of zirconium and titanium alkoxides (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 41-47 
    Details
    ISSN: 1573-4846
    Keywords: zirconium butoxide ; titanium butoxide ; kinetics ; hydrolysis ; condensation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A continuous flowing-rapid mixing technique was combined with FTIR, SAXS and electrical conductivity to study the early stages of polymer formation and growth during the acid-catalyzed hydrolysis and condensation of titanium and zirconium alkoxides. Reaction times as short as 80 milliseconds were investigated. FTIR spectroscopy was used to monitor the water and M−OR concentrations during the reaction. Hydrolysis of ∼25–50% of the alkoxy groups was facile. The FTIR and SAXS data showed that condensation was also very rapid. The activity and mobility of the ions in the solution were monitored by electrical conductivity measurements. The decrease in the normalized solution conductivity during the reaction correlated with the loss of [M−OR]. Furthermore, the radius of gyration of the growing polymers increased rapidly in regimes where the conductivity and [M−OR] decreased fastest. This finding suggests that the mobility of some of the charge carrying species decreases because of the growth in size of the polymers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02436815
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  • 96
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    Kinetics of oxidation of ferrous alloys by super-heated steam (1987)
    Springer
    Oxidation of metals 28 (1987), S. 237-258 
    Details
    ISSN: 1573-4889
    Keywords: Steel oxidation ; duplex scale ; steam ; activation energy ; kinetics
    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 the oxidation of ferrous alloys in steam (10–60 kPa) at 450–550°C have been studied by measuring both the rate of hydrogen emission and the amount of metal oxidized. Excellent agreement has been found between the amount of metal oxidized calculated from both the total mass of hydrogen produced in the reaction and the thickness of the oxide layer formed; rate constants calculated from the rate of hydrogen emission, the mass of hydrogen produced as the reaction proceeds, and the oxide formed agree within experimental error. The rate of oxidation of a 9%Cr-1%Mo alloy at 501°C was found to be independent of the partial pressure of the steam. For this alloy, the activation energy agreed with literature values obtained at higher temperatures and pressures. The effect of the chromium and silicon content on the oxidation rates is compared. The rate constants are compared with theoretical calculations, assuming that the rate is determined by diffusion of iron in the magnetite lattice. For the 9%Cr-1%Mo alloy, the parabolic rate constant and activation energy are in excellent agreement with values calculated using Wagner's theory. The experimental rate constants are greater for the alloys containing smaller amounts of chromium; diffusion of iron along magnetite grain boundaries may be the dominant mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00666721
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  • 97
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    The interaction of titanium and titanium alloys with nitrogen at elevated temperatures. I. The kinetics and mechanism of the titanium-nitrogen reaction (1976)
    Springer
    Oxidation of metals 10 (1976), S. 41-67 
    Details
    ISSN: 1573-4889
    Keywords: titanium ; nitridation ; kinetics ; diffusion ; scaling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The nitridation behavior of titanium has been examined in an atmosphere of nitrogen over the temperature range 900–1000° C. In addition to determining the reaction kinetics, microhardness and metallographic studies have been carried out on the nitrided substrates and nitride scales. Overall parabolic kinetics were exhibited, while a linear scaling reaction (associated principally with Ti2N formation) was observed. Extensive dissolution of nitrogen in the substrate was evident from the microhardness studies, and at 950 and 1000° C the growth of the nitrogen-stabilized αTi phase layer followed a parabolic law. Consideration of all the observed processes and derived data suggested that diffusion of nitrogen in the metal substrate was probably the rate-controlling mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00611698
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  • 98
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    Kinetics of high-temperature oxidation of boron carbide in oxygen (1976)
    Springer
    Oxidation of metals 10 (1976), S. 85-95 
    Details
    ISSN: 1573-4889
    Keywords: boron carbide ; oxidation ; kinetics ; chromatography method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Thermogravimetry and gas-adsorption chromatography were used to study the kinetics of formation of solid and gaseous products during the hightemperature oxidation of compact boron carbide in oxygen at 740 Torr. Oxidation resistance was observed at temperatures up to 1200°C. The main oxidation products were B2O3 and CO2. Oxidation was paralinear; the carbon consumption exceeded the consumption of boron as compared to the ratio of these elements in the compound B4C. This difference resulted in carbon depletion of the carbide layer in the substrate near the scale〉.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00614238
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  • 99
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    High-temperature oxidation of SiC in a glow-discharge oxygen plasma (1976)
    Springer
    Oxidation of metals 10 (1976), S. 97-103 
    Details
    ISSN: 1573-4889
    Keywords: silicon carbide ; oxidation ; molecular oxygen ; glow-discharge oxygen plasma ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation kinetics and structure of the oxide scales formed on high-density SiC were studied in molecular oxygen at 740 Torr and in a glow-discharge oxygen plasma at 0.1 Torr at temperatures of 1000, 1100, and 1200°C. The monatomic oxygen formed by the glow discharge markedly increased the reaction rate and the vaporization of some of the oxidation products. The marked differences in kinetics suggest that the rate-controlling step during oxidation in molecular oxygen is the dissociation of adsorbed diatomic oxygen to the monatomic species. Films formed in molecular oxygen were mostly amorphous SiO2 with small inclusions of SiC and graphite, whereas films formed in dissociated oxygen were primarily amorphous SiO2 containing SiO, S2O3, and the coesite form of SiO2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00614239
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  • 100
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    Theoretical study of heterogeneous reaction kinetics: A comparison between microcalorimetric and thermogravimetric curves (1976)
    Springer
    Oxidation of metals 10 (1976), S. 105-111 
    Details
    ISSN: 1573-4889
    Keywords: kinetics ; oxidation ; microcalorimetry ; thermogravimetry
    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 kinetic theories of Bodenstein or Semenov the expression for the rate of a chemical reaction with several elementary stages can be expressed by different physical parameters. If two experimental methods are used, one method of necessity being microcalorimetry to measure the thermal flux produced by the reaction, it is possible to distinguish a pure kinetics case from a mixed one. The two-method technique has been verified by a study of the oxidation of niobium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00614240
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