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  • kinetics
  • stability
  • Springer  (101)
  • Nature Publishing Group
  • 1980-1984  (101)
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Keywords
Publisher
  • Springer  (101)
  • Nature Publishing Group
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    On the stability of multistep formulas for Volterra integral equations of the second kind (1980)
    Springer
    Computing 24 (1980), S. 341-347 
    Details
    ISSN: 1436-5057
    Keywords: Numerical analysis ; Volterra integral equations of the second kind ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Ziel dieser Arbeit ist es, die Stabilitätseigenschaften einer Klasse Volterrascher Integralgleichungen zweiter Art zu untersuchen. Unsere Behandlung ist der üblichen Stabilitätsanalyse ähnlich, in der die Kernfunktionen zu einer im voraus beschränkten Klasse von Testfunktionen gehören. Wir haben die Klasse der “endlich zerlegbaren” Kerne betrachtet. Stabilitätsbedingungen werden abgeleitet und verglichen mit den Bedingungen für die einfache Testgleichung. Es zeigt sich, daß die neuen Kriteria einschränkender sind als die konventionellen Bedingungen. Der praktische Wert wird getestet durch numerische Experimente mit der Trapezregel.
    Notes: Abstract The purpose of this paper is to analyse the stability properties of a class of multistep methods for second kind Volterra integral equations. Our approach follows the usual analysis in which the kernel function is a priori restricted to a special class of test functions. We consider the class of finitely decomposable kernels. Stability conditions will be derived and compared with those obtained with the simple test equation. It turns out that the new criteria are more severe than the conventional conditions. The practical value is tested by numerical experiments with the trapezoidal rule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02237819
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  • 2
    Electronic Resource
    Electronic Resource
    Polymerization of acrylamide initiated by Ce(IV)-lactic acid redox system (1983)
    Springer
    Colloid & polymer science 261 (1983), S. 188-189 
    Details
    ISSN: 1435-1536
    Keywords: Polymerization ; kinetics ; redox polymerization ; acrylamide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01410701
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of specimen thickness on isothermal crystallization kinetics. A theoretical analysis (1984)
    Springer
    Colloid & polymer science 262 (1984), S. 366-373 
    Details
    ISSN: 1435-1536
    Keywords: kinetics ; isothermal crystallization ; polymer ; spherulite ; differential scanning calorimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In the DSC technique, isothermal crystallization experiments are usually performed on thin flat specimens, but their interpretation generally uses theories developed for an unbounded volume. In this paper, isothermal crystallization of spherical entities in the volume limited by two parallel infinite planes is considered. Our model, derived from Avrami's theory, gives an analytical expression for the transformed volume fraction as a function of time. It is shown that the influence of thickness becomes important when thickness becomes of the order of or smaller than the average spherulite radius. The main effects of a decreasing thickness are a slower crystallization kinetics and a decrease in the Avrami exponent. These results can be used to interpret experimental data obtained in isothermal polymer crystallization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01410254
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  • 4
    Electronic Resource
    Electronic Resource
    The effect of TiO2 on the kinetics of polyamide 6 crystallization (1983)
    Springer
    Colloid & polymer science 261 (1983), S. 621-625 
    Details
    ISSN: 1435-1536
    Keywords: Polyamide 6 ; crystallisation ; kinetics ; titania
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The kinetics of isothermal and nonisothermal crystallization of polyamide-6 (PA6) containing titania was studied by means of DSC. It was found thatTiO 2 causes an acceleration in the crystallization of polyamide-6 and lowers the value of the Avrami exponent,n. The presence of TiO2 does not affect equilibrium melting pointT m 0 , glass temperatureT g, or surface free energiesσ e andσ of the basal and lateral surfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01415030
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  • 5
    Electronic Resource
    Electronic Resource
    Three-dimensional disturbances of planar viscometric flow (1983)
    Springer
    Rheologica acta 22 (1983), S. 284-290 
    Details
    ISSN: 1435-1528
    Keywords: Viscometric flow ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract This paper examines three-dimensional disturbances of a plane steady shear flow of simple fluids with short memory. Under the assumption of nearly-viscometric flow, constitutive equations are derived and then a general form of the Reynolds-Orr energy equation is obtained. With the aid of this derived energy formula, sufficient conditions are generated for the stability of three-dimensional disturbances of the planar viscometric flow. These conditions are analysed and a comparison is made with the corresponding two-dimensional stability problem. There is a strong indication that the basic flow is less stable against three-dimensional disturbances than against two-dimensional ones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01359128
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  • 6
    Electronic Resource
    Electronic Resource
    Proceedings: Ad Hoc Mathematical Fire Modeling Working Group (1984)
    Springer
    Fire technology 20 (1984), S. 47-63 
    Details
    ISSN: 1572-8099
    Keywords: Extinguishment ; fire modeling ; mass loss ; heat release ; char ; reflash ; sprinklers ; radiant flux ; kinetics ; reaction rate ; heat loss ; ash ; latent heat ; spray density ; extinguishing agents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract The Ad Hoc Mathematical Fire Modeling Working Group was organized about seven years ago to facilitate voluntary cooperation and coordination in developing mathematical fire modeling capability. The group has a steering committee of representatives of agencies that support fire modeling and related research. These include the National Bureau of Standards' Center for Fire Research, Factory Mutual Research Corp., the Naval Research Laboratory, NASA, and the Federal Aviation Agency. The Group holds plenary meetings when it seems desirable to do so (about once each 1 1/2 years), and workshops on topical subjects. Three workshops were held in 1983. Normally, Group meetings are held before or after other meetings at which a number of interested personnel would likely be present. Minutes are mailed to those who attended and to others (including European and Japanese personnel) who have indicated interest. This workshop was arranged by Ron Alpert of Factory Mutual Research Corp. and held at their facilities at Norwood, MA, in November 1983.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02384150
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of pressure on the kinetics of the dehydration of carbonic acid and the hydrolysis of CO2 in aqueous solution (1982)
    Springer
    Journal of solution chemistry 11 (1982), S. 339-346 
    Details
    ISSN: 1572-8927
    Keywords: Carbon dioxide ; hydrolysis ; aqueous solution ; kinetics ; activation volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pressure dependence of the dehydration reaction of H2CO3 was measured in acidic aqueous solution for pressures up to 1 kbar using a high-pressure stopped-flow instrument. The corresponding volume of activation was found to be 6.4±0.4 cm3-mol−1 at 25°C and 0.5 ionic strength. Volume equation calculations result in a value of −9.9±1.9cm3-mol−1 for the volume of activation for the hydrolysis of CO2 under the same conditions. For the first time, the reaction mechanism can be interpreted in terms of dissociative and associative modes, respectively. These data are used to construct an overall reaction volume profile.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00649292
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  • 8
    Electronic Resource
    Electronic Resource
    Thermodynamic parameters of coupled chemical reactions from temperature jump relaxation amplitudes (1981)
    Springer
    Journal of solution chemistry 10 (1981), S. 39-50 
    Details
    ISSN: 1572-8927
    Keywords: Temperature jump ; kinetics ; thermodynamics ; TRIS ; iminodiacetic acid ; magnesium ion ; phenol red
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Equations describing the temperature jump amplitudes associated with a system of two coupled reactions (TRIS-phenol red) as well as the ternary system (Mg2+-iminodiacetic acid-phenol red) are presented. The termodynamic parameters calculated from experimentally measured temperature perturbation amplitudes using a multiparametric curve fitting procedure are found to be in good agreement with those determined from pH- and costant rate thermometric titrations. For phenol red, pK I =7.55, ΔH I =3.45 kcal, and for Mg2+ iminodiacetic acid, log K M =2.84, ΔH M =3.25 kcal, were obtained. It is shown that this method can be used to determine accurate thermodynamic enthalpy changes over a narrow temperature interval of less than 1.0°C from a single experiment requiring about 50 μl of sample solution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00652779
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  • 9
    Electronic Resource
    Electronic Resource
    Rate and thermodynamic studies of the interaction between water and iso-butyl cellosolve by ultrasonic methods (1983)
    Springer
    Journal of solution chemistry 12 (1983), S. 771-781 
    Details
    ISSN: 1572-8927
    Keywords: Ultrasonics ; kinetics ; aqueous solution ; iso-butyl cellosolve
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Ultrasonic absorption and velocity measurements in aqueous solution of iso-butyl cellosolve (ethylene glycol iso-butyl ether) as a function of the concentration are reported. The two relaxational absorptions have been attributed to the perturbation of the equilibria expressed by AB⇌A+B and Aα(1/n)An where A is the solute, B is the solvent, AB is the complex and A n is the solute aggregate. The rate constants for each step have been determined. From the concentration dependence of the maximum excess absorption per wave length, the enthalpy change and the volume change for the reaction between the solute and the solvent have been determined for aqueous solutions of butyl cellosolve (ethylene glycol n-butyl ether), iso-butyl cellosolve and propyl cellosolve (ethylene glycol n-propyl ether). The results are consistent with a hydrogen bonding reaction. The effect of the ethers on water structure are considered and it is clear that the fraction of water molecules which can hydrogen bond to the solute decreases with the increasing hydrophobicity of the solute.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00653180
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  • 10
    Electronic Resource
    Electronic Resource
    Enthalpies of reaction and reaction rates by flow microcalorimetry: Ester hydrolysis in basic medium (1980)
    Springer
    Journal of solution chemistry 9 (1980), S. 59-73 
    Details
    ISSN: 1572-8927
    Keywords: Enthalpies of reaction ; heats of reaction ; kinetics ; ester hydrolysis ; microcalorimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The conditions under which the Picker flow microcalorimeter can be used to measure enthalpies and rates of reactions were investigated. For this purpose, systematic studies were made of the enthalpies of neutralization of HCl, HBr, HNO 3 , acetic, proprionic, and butyric acids with NaOH, enthalpies of hydrolysis of methyl and ethyl acetate with NaOH, and the reaction rates of the ester hydrolysis with NaOH. The general procedure and various sources of error are discussed and it is concluded that enthalpies of slow reactions can be measured to about 1% when the calorimeter is operated in the quasi-isothermal mode and the reaction rates to about 3% when operated in the quasi-adiabatic mode.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00650137
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  • 11
    Electronic Resource
    Electronic Resource
    A stability investigation for an incompressible simple fluid with fading memory (1980)
    Springer
    Archive for rational mechanics and analysis 72 (1980), S. 203-218 
    Details
    ISSN: 1432-0673
    Keywords: simple fluid ; viscoelastic ; fading memory ; stability ; Liapunov function ; dynamical system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract The nonlinear equations of motion for an incompressible simple fluid, occupying a fixed bounded container, are formulated on the basis of the “finitelinear” viscoelasticity theory for materials with fading memory; this formal boundary-initial value problem is then viewed as a nonlinear abstract evolution equation on a certain Hilbert space. It is shown that a linearized version of this evolution equation is associated with a linear dynamical system on this Hilbert space, and several results for stability and asymptotic behavior for this linearized problem are proved through the use of Liapunov stability methods. On the assumption that the original nonlinear evolution equation also is associated with some dynamical system on the same space, it is shown that the rest condition of the fluid is stable and all motions are bounded. The Liapunov function employed for this purpose can be interpreted as a mechanical energy function for the fluid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00281589
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  • 12
    Electronic Resource
    Electronic Resource
    Difference schemes for the dispersive equation (1983)
    Springer
    Computing 31 (1983), S. 261-267 
    Details
    ISSN: 1436-5057
    Keywords: 65M10 ; Dispersive equation ; finite difference ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Dieser Artikel beinhaltet eine Zusammenstellung von Differenzenverfahren für die Dispersionsgleichungu 1=au xxx. Es werden Kriterien zur Herleitung von Stabilitätsbedingungen für Differenzenverfahren angegeben und auf die angegebenen Differenzenverfahren angewendet.
    Notes: Abstract In this paper a table of difference schemes for the dispersive equationu i=au xxx is presented. A collection of criterions for deriving stability conditions of difference schemes is given and applied to these difference schemes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02263436
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  • 13
    Electronic Resource
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    D-stability and Kaps-Rentrop-methods (1984)
    Springer
    Computing 32 (1984), S. 229-237 
    Details
    ISSN: 1436-5057
    Keywords: 65L05 ; 65L07 ; Stiff system ; Rosenbroek method ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung In dieser Arbeit wird die Stabilität des Kaps-Rentrop-Verfahrens in die Anwesenheit nichtlinearer Steifheit (Stiffness) analysiert. Dazu werden mittels eines einfachen Modells zwei Größen introduziert. Die Werte dieser Größen reflektieren gewissermaßen das Verhalten eines Kaps-Rentrop-Verfahrens in die Anwesenheit einer bestimmten Kopplung zwischen die beiden Komponenten in das steife System gewöhnlicher Differentialgleichungen. Einige numerische Beispiele veranschaulichen die Analyse.
    Notes: Abstract In this paper we give an analysis of the effect of stiff nonlinearities on the behavior of a Kaps-Rentrop method. To that end we introduce two quantities related to a simple model. The values of these quantities determine to some extent the behavior of a Kaps-Rentrop method in case of a strong coupling between the smooth component and the transient one. Numerical examples illustrate the theoretical results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02243574
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  • 14
    Electronic Resource
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    Correlation inequalities and the thermodynamic limit for classical and quantum continuous systems II. Bose-Einstein and Fermi-Dirac statistics (1980)
    Springer
    Journal of statistical physics 23 (1980), S. 701-753 
    Details
    ISSN: 1572-9613
    Keywords: Correlation inequalities ; classical and quantum continuous systems ; positive type potentials ; stability ; thermodynamic limit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We study quantum mechanical systems of particles with Bose or Fermi statistics interacting via two-body potentials of positive type in thermal equilibrium. We rewrite partition functions, reduced density matrices (RDMs), and correlation functions in terms of Wiener and Gaussian functional integrals (sine-Gordon transformation). This permits us, e.g., to apply correlation inequalities. Our main results include an analysis of stability versus instability in the grand canonical ensemble and, for charge-conjugation-invariant systems, upper and lower bounds on RDMs, the existence of the thermodynamic limit of pressure, RDMs and correlation functions, an inequality comparing correlations with Fermi statistics to ones with Bose statistics, and inequalities which are important in the study of Bose-Einstein condensation and of superconductivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01008516
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  • 15
    Electronic Resource
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00627923
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  • 16
    Electronic Resource
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00545219
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  • 17
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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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  • 18
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    Increased oral clearance of metoprolol in pregnancy (1983)
    Springer
    European journal of clinical pharmacology 24 (1983), S. 217-220 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF00613820
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  • 19
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00543788
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  • 20
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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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    Lack of dose dependent kinetics of theophylline (1983)
    Springer
    European journal of clinical pharmacology 24 (1983), S. 525-527 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF00609897
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  • 22
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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 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF00549600
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  • 23
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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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    Improved effect of glibenclamide on administration before breakfast (1982)
    Springer
    European journal of clinical pharmacology 21 (1982), S. 403-408 
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    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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    URL: http://dx.doi.org/10.1007/BF00542327
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  • 25
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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 
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    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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    Effect of quinidine on digoxin bioavailability (1983)
    Springer
    European journal of clinical pharmacology 24 (1983), S. 41-47 
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    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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    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 
    Details
    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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    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 
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    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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    URL: http://dx.doi.org/10.1007/BF00607091
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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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    Kinetics of phenobarbital in normal subjects and epileptic patients (1982)
    Springer
    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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    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 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF00613821
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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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    Influence of hyperthyroidism on the kinetics of methimazole, propranolol, metoprolol and atenolol (1982)
    Springer
    European journal of clinical pharmacology 21 (1982), S. 379-384 
    Details
    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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    Glibenclamide pharmacokinetics in acarbose-treated type 2 diabetics (1984)
    Springer
    European journal of clinical pharmacology 27 (1984), S. 233-236 
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    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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    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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    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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    Pharmacokinetics of furosemide in neonates (1982)
    Springer
    European journal of clinical pharmacology 22 (1982), S. 39-45 
    Details
    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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    Elimination of azlocillin in patients with biliary t-tube drainage (1982)
    Springer
    European journal of clinical pharmacology 22 (1982), S. 435-439 
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    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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    Kinetics and metabolism of (+)-, (−)- and (±)-bufuralol (1982)
    Springer
    European journal of clinical pharmacology 23 (1982), S. 529-533 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF00637501
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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 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF00613825
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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 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF00606421
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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 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF00542456
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    Kinetic and spectroscopic analysis of NH3 decomposition under R.F. Plasma at moderate pressures (1981)
    Springer
    Plasma chemistry and plasma processing 1 (1981), S. 19-35 
    Details
    ISSN: 1572-8986
    Keywords: Decomposition of NH3 ; kinetics ; optical spectroscopy ; gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The plasma decomposition of NH3 has been studied as a function of the residence time, power input, and pressure. The process follows apparently zero-order kinetics, which can be interpreted on the basis of a kinetic mechanism involving as initial step the rupture of an N-H bond from vibro-rotationally excited modecules. Simultaneous spectroscopic observations of the emission light due to electronically excited NH2, NH, H, and N2 have been used to confirm the suggested mechanism and to show that NH2 and NH are successive intermediate species and that the final step of the decomposition process is the bimolecular recombination NH+NH→N2+H2.
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    Mechanism and kinetics of polymerization of propylene in a microwave plasma (1981)
    Springer
    Plasma chemistry and plasma processing 1 (1981), S. 233-245 
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    ISSN: 1572-8986
    Keywords: Plasma ; kinetics ; polymerization ; propylene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Flowing microwave plasma of propylene and propylene with argon was studied by mass spectrometry. Plasma composition was investigated as a function of external parameters such as pressure, argon/propylene ratio, and microwave-induced power. It was found that the propylene broke down to C2H2 and CH4, or reacted further with propylene. Two main products, leading to the determination of three main chain reactions for the polymerization of propylene by ion-molecule interactions, were observed, namely, C2H2 and CH4. These were the propylene, acetylene, and ethylene chain reactions. It was also found that the propylene disappeared in a pseudo-first-order reaction. Consequently an overall rate constant for the polymerization was determined (50 sec−1 at 1 torr pressure for propylene plasma). This constant is found to be linearly dependent upon the propylene percent concentration, and nonlinearly dependent upon plasma pressure.
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    Comparison of renal ornithine transcarbamylase activities within different chicken breeds (1981)
    Springer
    Biochemical genetics 19 (1981), S. 881-893 
    Details
    ISSN: 1573-4927
    Keywords: chicken kidney ; ornithine transcarbamylase ; Cochin Bantam ; White Leghorn ; genetics ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Comparisons were made of the renal ornithine transcarbamylase (OTC) activities within different groups of chickens including Japanese native breeds. OTC activities varied markedly within these groups. The Cochin Bantam breed and White Leghorn B line had an especially high activity, about 400 units/g of kidney, in contrast to two Japanese native breeds, Japanese Game (white variety) and Banshuu Gashiwa, and the California Gray breed, which showed a very low activity, the values being almost undetectable. In crossing experiments using the California Gray breed as a tester strain, Cochin Bantam OTC represents a simple autosomal incompletely dominant trait similar to the White Leghorn B line OTC. Kinetic studies using partially purified OTC preparations from the White Leghorn B line and Cochin Bantam breed revealed that both enzymes were identical for a variety of enzymic characteristics. In light of these results, the physiological significance of chick kidney OTC is discussed.
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    URL: http://dx.doi.org/10.1007/BF00504253
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    Oxidation of Ti-1Si and Ti-5Si alloys (1982)
    Springer
    Oxidation of metals 17 (1982), S. 359-369 
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    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.
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    URL: http://dx.doi.org/10.1007/BF00742117
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    Oxidation of ternary Co-Cr-W alloys (1983)
    Springer
    Oxidation of metals 20 (1983), S. 37-65 
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    ISSN: 1573-4889
    Keywords: Alloy oxidation ; cobalt-chromium-tungsten ; scale formation ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Oxidation rates in air at 1000–1250°C are reported for a series of Co-Cr-W alloys with 34–40 wt. % Cr and up to 10 wt. % W. Alloys with larger W contents exhibited slower oxidation rates and their parabolic rate constants agreed well with those for binary and ternary, Cr2O3 protected, Ni-base and Co-base alloys in the Co-Cr and Ni-Cr-W systems. The resulting scales were characterized by optical and scanning electron metallography, and electron microprobe analysis. The favorable effect of W additions to a Cr2O3-forming Co-Cr base alloy was the opposite of that reported for Ni-Cr-W alloys. The resupply of Cr to a Cr-depleted matrix beneath a protective CrO3 scale is achieved by the dissolution (denuding) of Cr-rich second phases in the Co-Cr-W alloys. Thus, the internal oxidation of Cr beneath the Cr2O3 scale is avoided for high W alloys. No catastrophic failure by liquid phase formation was observed for high-W alloys oxidized 20 hr at 1250°C.
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    URL: http://dx.doi.org/10.1007/BF00658126
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    The influence of inorganic phosphate and ATP on the kinetics of bovine heart muscle pyruvate kinase (1984)
    Springer
    Molecular and cellular biochemistry 64 (1984), S. 45-50 
    Details
    ISSN: 1573-4919
    Keywords: cardiac muscle ; kinetics ; pyruvate kinase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary The mechanism of activation by inorganic phosphate and ATP of cardiac muscle pyruvate kinase was studied with the aid of steady-state kinetics. The enzyme was purified to homogeneity to a final specific activity of 400 units/ mg (phosphate buffer, pH 7.6, 25 °C). At pH 7.6 the enzyme displays Michaelis-Menten kinetics with respect to both its substrates, phosphoenolpyruvate and ADP. Substrate kinetic constants are: app.Km(phosphoenolpyruvate) −0.04 mM, app.Km(ADP) =0.22 mM. Under the conditions used in the standard assay the specific activity is greatly enhanced by inorganic phosphate (50 mM) or ATP (2.5 mM). Each of these modifiers, acting separately, increases the Vmax without seriously affecting Michaelis constants and Hill coefficients. In the presence of both Pi and ATP, only a decrease in Vmax was observed. The kinetics of activation by inorganic phosphate of pyruvate kinase was examined. Studying the effect of varying concentrations of Pi on the initial rate we obtained a hyperbolic saturation curve with the app. Km(Pi) = 20 mM and Vmax = 167 units/ mg. The evidence is presented that inorganic phosphate is a substrate for a side reaction catalyzed by cardiac pyruvate kinase. It is shown that in the presence of pyruvate, inorganic phosphate and ATP in the assay system, Pi is incorporated into acid-labile products of this reaction, inorganic pyrophosphate being one of them. These findings indicate the existence of an alternative reaction catalyzed by pyruvate kinase by which energy may be stored in the form of inorganic pyrophosphate.
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    URL: http://dx.doi.org/10.1007/BF00420927
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    Oxidation of Ni-Cr-W ternary alloys (1980)
    Springer
    Oxidation of metals 14 (1980), S. 85-108 
    Details
    ISSN: 1573-4889
    Keywords: alloy oxidation ; nickel-chromium-tungsten ; scale formation ; 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 in air at 1000–1250°C of four Ni-Cr-W alloys containing sufficient chromium content (∼22 at. % Cr) for protective Cr2O3 formation in a binary Ni-Cr alloy is reported. Generally for alloys high in W (10 and 16 at.% W), the rejection of tungsten into the alloy beneath the scale introduced a steep Cr concentration gradient and slower Cr diffusion such that continuous precipitation of Cr2O3 internal oxides prevented the formation of a Cr2O3 protective scale. The alloy most dilute in W (1.6 at. % W) formed a protective scale at short times with little outer NiO scale, but scale fractures led to internal oxidation and rapid nonprotective kinetics. After an initially rapid oxidation increment to form NiO, the 3 at.% Walloy formed a protective Cr2O3 scale with about the same steady-state parabolic kinetics as a binary Ni-30Cr alloy. The effect of ternary Wadditions on the development of Cr2O3 scales on Ni-Cr-W alloys is considered as a ternary analog to Wagner's description of the oxidation of Cu-Pt or Cu-Pd alloys.
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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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    Nitriding of chromium in nitrogen gas at high temperatures (1981)
    Springer
    Oxidation of metals 15 (1981), S. 437-445 
    Details
    ISSN: 1573-4889
    Keywords: chromium nitriding ; kinetics ; parabolic rate constant ; diffusivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Parabolic rate constants of the reaction of chromium with nitrogen gas under oxygen-free conditions have been determined over a range of temperature (1000–1250°C) and nitrogen pressure (0.265–101.33 kPa). The growth rate of the subnitride was measured by a thermogravimetric technique using a single specimen. Wagner's oxidation theory is used to calculate the self-diffusivity and intrinsic diffusivity of nitrogen in the subnitride from a theoretical analysis of the parabolic rate constant. The calculated diffusivities varied with the composition of the subnitride, having minimum values at intermediate compositions of the nonstoichiometric chromium nitride “Cr2N.”
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    The scaling of a Fe-20Cr alloy in H2-H2O-H2S mixtures (1981)
    Springer
    Oxidation of metals 16 (1981), S. 175-191 
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    ISSN: 1573-4889
    Keywords: Sulfidation ; Fe-Cr alloy ; 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 scaling of an Fe-20Cr alloy has been studied in H2-H2O-H2S mixtures between 973 and 1223 K. According to a simplified phase diagram, Cr2O3 and FeS should be the thermodynamically stable compounds in the gas mixtures chosen. The reaction followed a mixed rate law between linear and parabolic, indicating that the reaction rate at the scale-gas interface was comparable with the diffusion rate in the scale. At a constant H2/H2S ratio the scaling rate initially decreased slightly with increasing water-vapor pressure. A further increase of the water-vapor pressure resulted in localized sulfide formation, while the other parts of the surface were covered with a Cr2O3 film. Only Cr2O3 formed above a critical water-vapor content. Three zones could be distinguished when a sulfide scale is formed. The outer zone consisted of practically pure FeS; the intermediate zone was a solid solution of (Fe,Cr)S, partially decomposed to FeCr2S4 and metal during cooling; and the inner zone contained small Cr2O3 inclusions in an (Fe,Cr)S matrix.
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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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    Sulfidation behavior of austeno-ferritic steels (1984)
    Springer
    Oxidation of metals 21 (1984), S. 103-118 
    Details
    ISSN: 1573-4889
    Keywords: duplex steels ; sulfidation ; kinetics ; transport processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Two austeno-ferritic stainless steels were sulfidized at temperatures of 783, 873, and 963 K under sulfur pressures in the range 4×10−12 to 3×10−5 atm. In all cases a triplex scale developed, consisting of an outermost layer of (Fe, Cr)1−xS, an intermediate layer of FeCr2S4, and an innermost layer of porous (Cr, Fe)1−xS containing particles of Mo2S3. Parabolic kinetics were observed except at the lowest temperature where one of the steels reacted according to irregular kinetics. The Mo2S3 particles in the innermost layer acted as inert markers, imaging the former positions of the steels' ferrite phase in which Mo is enriched. The lamellar microstructure of the steel was thus reproduced in the innermost sulfide layer. The positions of the Mo2S3 particles together with the porosity of the inner layer are taken to imply inward sulfur transport through this layer and outward metal transport through all three layers.
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    High-temperature oxidation of Ti-4.32 wt.% Nb alloy (1980)
    Springer
    Oxidation of metals 14 (1980), S. 147-165 
    Details
    ISSN: 1573-4889
    Keywords: oxidation in air or oxygen ; kinetics ; oxide identification ; oxygen 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 oxidation kinetics of Ti-4.32 wt.% Nb (2.27 at.%) alloy in either air or oxygen under 1 bar pressure have been investigated in the temperature range of 1255–1471 K. For oxidation in oxygen the kinetics follow consecutively decreasing parabolic rate laws. The kinetics become nonparabolic after prolonged oxidation in air. X-ray data reveal the presence of TiO2 (rutile) as the main oxide. The presence of Ti2O, δ-TiN, and ɛ-TiN is found on the metal surface after oxidation in air. Microhardness and electron microprobe measurements are used to determine Ti, Nb, O, and N profiles across the oxidized alloy. The oxygen diffusion coefficient in the alloy can be expressed byD=65.6 exp(−234.3/RT) with the activation energy in kilojoules per mole. The oxidation behavior of the alloy is explained.
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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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    The initial oxidation of iron at 200° and 300° C and the effect of surface sulfur (1981)
    Springer
    Oxidation of metals 16 (1981), S. 107-131 
    Details
    ISSN: 1573-4889
    Keywords: Oxidation ; iron ; kinetics ; sulfur ; surface analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The growth of thin (0–200 Å) oxide films on iron at 200 and 300 °C has been studied as a function of time and oxygen partial pressure using proton-induced X-ray emission (PIXE) and Auger electron spectroscopy (AES). Oxidation was found to be initially retarded by sulfur which had segregated onto the iron surfaces during preoxidation annealing, but only if the iron surface contained the maximum or near-maximum sulfur coverage (ca. one-half monolayer). During and immediately following the oxygen-sulfur interaction, oxide buildup appeared to be limited by a surface reaction (adsorption, ionization, or dissociation). For most of the oxidation period, pressure-dependent logarithmic oxide growth was observed at 200°C, and pressure-independent parabolic oxide growth at 300°C. Interpretation of the data indicated that oxide growth at 200°C may be limited by quantum mechanical tunneling of electronic species through the previously formed oxide film, and oxide growth at 300°C may be limited by ionic diffusion through the previously formed oxide film. Comparison of AES and PIXE data indicated that the oxide films formed at 200°C were uniform in thickness over the surface of the metal, whereas films formed at 300°C had relatively thin areas where sulfur had remained.
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    URL: http://dx.doi.org/10.1007/BF00603747
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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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    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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    Purification and characterization of mouse alcohol dehydrogenase from two inbred strains that differ in total liver enzyme activity (1984)
    Springer
    Biochemical genetics 22 (1984), S. 115-124 
    Details
    ISSN: 1573-4927
    Keywords: alcohol dehydrogenase ; inbred mouse strains ; enzyme structure ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Alcohol dehydrogenase activity in mouse liver homogenate-supernatants is 1.7 times greater in the C57BL/10 strain than in the BALB/c strain, regardless of whether activity is expressed in units per gram liver, total liver, or milligram DNA. The K m values for ethanol and NAD+, approximately 0.4 and 0.03mm, respectively, of enzyme purified from both strains are similar. Moreover, the K i for NADH, 1 µm, the pH optimum for ethanol oxidation, 10.5, and the V max for ethanol oxidation, 160 min−1, for ADH from the C57BL/10 and BALB/c strains are similar. Therefore, the difference in ADH activity in the two strains cannot be due to differences in the catalytic properties of the enzyme. The electrophoretic and isoelectric focusing patterns and two-dimensional tryptic peptide maps of the purified enzyme from both strains are identical. Thus the amino acid sequences of enzyme from C57BL/10 and BALB/c mice must also be identical or very similar. The difference in ADH activity in the two strains is most likely the result of genetic differences in the content of ADH protein in liver.
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    URL: http://dx.doi.org/10.1007/BF00499291
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    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.
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    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.
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    Na+, Li+ and Cl− transport by brush border membranes from rabbit jejunum (1983)
    Springer
    The journal of membrane biology 74 (1983), S. 85-94 
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    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.
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    The kinetics of transport inhibition by noncompetitive inhibitors (1983)
    Springer
    The journal of membrane biology 74 (1983), S. 175-182 
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    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.
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    Existence and stability of equilibria in age-structured population dynamics (1984)
    Springer
    Journal of mathematical biology 20 (1984), S. 259-276 
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    ISSN: 1432-1416
    Keywords: Age-structured population dynamics ; equilibria ; stability ; bifurcation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract The existence of positive equilibrium solutions of the McKendrick equations for the dynamics of an age-structured population is studied as a bifurcation phenomenon using the inherent net reproductive rate n as a bifurcation parameter. The local existence and uniqueness of a branch of positive equilibria which bifurcates from the trivial (identically zero) solution at the critical value n=1 are proved by implicit function techniques under very mild smoothness conditions on the death and fertility rates as functional of age and population density. This first requires the development of a suitable linear theory. The lowest order terms in the Liapunov-Schmidt expansions are also calculated. This local analysis supplements earlier global bifurcation results of the author. The stability of both the trivial and the positive branch equilibria is studied by means of the principle of linearized stability. It is shown that in general the trivial solution losses stability as n increases through one while the stability of the branch solution is stable if and only if the bifurcation is supercritical. Thus the McKendrick equations exhibit, in the latter case, a standard exchange of stability with regard to equilibrium states as they depend on the inherent net reproductive rate. The derived lower order terms in the Liapunov-Schmidt expansions yield formulas which explicitly relate the direction of bifurcation to properties of the age-specific death and fertility rates as functionals of population density. Analytical and numerical results for some examples are given which illustrate these results.
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    Predator-prey relationships: Indiscriminate predation (1984)
    Springer
    Journal of mathematical biology 21 (1984), S. 25-34 
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    ISSN: 1432-1416
    Keywords: Predator-prey ; density dependence ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract The Gurtin and Levine model5 is studied in this paper under the assumption that the fecundity of prey depends on age as well as on the total population sizes of prey and predators. The purpose of this study is to see the effect of this density dependence on the stability criteria for the equilibria of the model equations. It is shown that there are cases when, due to density dependence, the model which is originally neutrally stable becomes stable.
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    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.
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    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 
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    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.
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    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 
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    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.
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    Monitoring the kinetics of the antigen-antibody reaction by a light scattering method (1983)
    Springer
    Bulletin of experimental biology and medicine 95 (1983), S. 151-153 
    Details
    ISSN: 1573-8221
    Keywords: antigen-antibody reaction ; kinetics ; laser ; scattering of light
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
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    URL: http://dx.doi.org/10.1007/BF00831252
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    Kinetics of drug displacement interactions (1981)
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    Journal of pharmacokinetics and pharmacodynamics 9 (1981), S. 181-190 
    Details
    ISSN: 1573-8744
    Keywords: drug displacement ; interaction ; kinetics ; simple model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A simple model simulating the kinetics of drug displacement kinetics is investigated. It is demonstrated that for highly bound, lowly cleared drugs, displacement interactions are transitory. Consequently, the kinetics of the interaction have to be considered as well as the in vitrointeraction. It is possible to have a significant in vitrodisplacement interaction with no in vivocounterpart. Methods of moderating drug displacement by adjusting the rate and the timing of administration of the displacing agent are discussed.
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    Time separation technique for large databases (1983)
    Springer
    International journal of parallel programming 12 (1983), S. 193-209 
    Details
    ISSN: 1573-7640
    Keywords: Database ; characteristic frequency ; aggregated model ; decomposition ; stability ; dynamic distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract A time decomposition technique is suggested for large-database (DB) models. The problem of network aggregation is studied and the results used to create a meaningful decomposed model. Decomposition conditions and assumptions are discussed and illustrated by examples. A practical operating schedule is presented for the time-separated DB model. The schedule uses a sequence of decomposed models, which are to be constructed recursively. The application of the time separation technique for large-DB models is presented in the form of a closed-loop algorithm. The problem of decomposition stability with respect to variations in time constants is considered as well. Two alternative approaches to the problem are suggested. For a probabilistic approach, practical approximate formulas are obtained for subsystem time constants and recommendations are made with respect to the decomposition structure. An approximate performance analysis is done for both standard and time-decomposed models. A comparison of the results is given.
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    The pharmacokinetics of furazlocillin in healthy humans (1983)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 11 (1983), S. 5-30 
    Details
    ISSN: 1573-8744
    Keywords: furazlocillin acylureido penicillin ; stability ; microbiological ; high pressure liquid chromatography assays ; red cell partitioning ; plasma protein binding ; healthy humans ; posture independent ; dose dependent pharmacokinetics of disposition ; pharmacokinetics of the penicilloic acid derivative
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pharmacokinetics of the novel acylureidopenicillin furazlocillin, 6-[D-2-(3-furfurylidenamino-2-oxo-imidazolidine-1-carboxamido)-2-(4-hydroxyphenyl)-acetamido]-penicillanic acid and of its penicilloic acid derivative were investigated in five healthy male volunteers after intravenous administration of 2 and 4 g dosages. The volunteers were either in a lying or sitting position throughout the duration of the studies. The concentrations of the drug in plasma and urine were measured by two different methods in parallel: a microbiological assay and a newly developed high pressure liquid chromatography method. The latter method was also applicable for quantitation of the penicilloic acid derivative in these biological fluids. The drug's plasma protein binding (66%) and apparent red cell-plasma partition coefficient (0.055) were concentration independent. The pharmacokinetics of the drug were first order only at the lower dose level The apparent half lives of three distinguishable phases were, respectively, 4 $$(t_{1/2_1 } )$$ , 18 $$(t_{1/2_2 } )$$ , and 64 $$(t_{1/2_z } )$$ .
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    The effect of hepatic uptake on the disappearance of warfarin from the plasma of rats: A kinetic analysis (1983)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 11 (1983), S. 127-145 
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    ISSN: 1573-8744
    Keywords: warfarin ; dose dependent clearance ; hepatic uptake ; model ; kinetics ; nonlinearity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract To quantify the effects of the liver on the dose dependence of plasma warfarin clearance, an equal number of normal and functionally hepatectomized rats received an intravenous bolus of either 0.01, 0.1, or 1.0 mg/kg body weight of radiolabelled sodium warfarin. Serial samples of plasma and bile collected from each rat during the 1 hr experiment and of hepatic tissue collected at the end of the experiment were analyzed for radioactivity. The disappearance of warfarin from the plasma of hepatectomized rats was not dose dependent and suggested that the apparent dose dependency of plasma warfarin clearance is primarily the result of warfarin's interaction with hepatic tissue. The disappearance of warfarin from the plasma of normal rats was dose dependent with higher doses being cleared less rapidly. This dose dependence, however, was not reflected in the rate of biliary excretion of warfarin's metabolites, which did not show saturation over this dosage range. These results were used to develop a multicompartmental model of warfarin's pharmacokinetics. Plasma warfarin data collected from the hepatectomized rats were used to develop the extrahepatic components of the model, which was then expanded to include hepatic tissues based on data collected from normal rats. To simultaneously fit the plasma, biliary, and hepatic data required that at least two classes of hepatic tissue exchange warfarin with plasma. One tissue exhibited Michaelis-Menten saturation kinetics with Kd and maximum capacity estimated at 1.49E-3μg/ml and 2.72 μg/ml, respectively. The second class exhibited linear exchange kinetics with free plasma warfarin. Warfarin's association with the second class of hepatic tissue leads to its metabolic elimination. Consistent with our experimental findings, the rate of warfarin elimination from the plasma into the bile was linearly related to plasma warfarin concentration. Thus the single hepatic exchange nonlinearity was necessary and sufficient to account for the apparent dose dependency in plasma warfarin's pharmacokinetics. These results suggest that over the range of doses studied, the apparent dose dependent differences in the plasma warfarin concentration profile can be accounted for by saturable hepatic uptake. This mechanism, however, is not related to warfarin's metabolic enzymes, which do not show saturation in the dosage range studied.
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    The stability of induced compact mutant clones of Bramley's Seedling apple (1982)
    Springer
    Euphytica 31 (1982), S. 451-459 
    Details
    ISSN: 1573-5060
    Keywords: Malus ; apple ; gamma radiation ; mutants ; compact clones ; stability ; chimaera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Twelve selected, compact, clones of Bramley's Seedling induced by gamma radiation treatment were checked for stability. Representative trees were used as vegetative parents for large scale multiplication, and further buds were treated with gamma radiation to disrupt the structure of their meristems. The results indicate that seven of the clones are as stable as the original cultivar, and therefore probably homohistont, containing only cells with compact mutant genotype. The other five clones proved to be unstable and gave rise to a large proportion of apparently normal trees. It is hypothesized that in these clones the L1 (epidermis) consists of normal unchanged tissue, while the bulk of the plant tissue layers are of mutant cells, i.e. that they are periclinal chimaeras with the genotypes of the different cell layers coded for different growth forms.
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    Stability analysis over seasons and locations of multilines of wheat (Triticum aestivum L.) (1984)
    Springer
    Euphytica 33 (1984), S. 489-495 
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    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; multilines ; recurrent parents ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Three multilines each of Kalyansona and PV 18 varieties of wheat were compared for their stability of yield and agronomic characters and disease resistance against the respective recurrent parents. The experiments were conducted for four years at nine locations. The multilines had more tillers and bolder seeds than the recurrent parents. There were, however, no differences for plant height, ear length and number of spikelets per spike. The genotypes x years x locations interaction was much more important than genotypes x years or genotypes x locations interaction as well as the main effects for genotypes. It is suggested that the number of test locations should be increased while decreasing the number of years. The stability parameters indicated that the multilines had a higher mean yield in the case of Kalyansona multilines whereas the yield of multilines of PV 18 was not significantly inferior to that of the recurrent parent. The regression coefficients were very close to unity except for KSML 3 (b=1.132). The deviations from regression were much larger for the multilines than for the recurrent parents. For rust resistance the multilines were superior over the varieties Kalyansona and PV 18.
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    Temperature dependence of mitochondrial oligomycin-sensitive proton transport ATPase (1984)
    Springer
    Journal of bioenergetics and biomembranes 16 (1984), S. 391-406 
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    ISSN: 1573-6881
    Keywords: OS-ATPase ; temperature effect ; kinetics ; lipid role ; membrane enzyme ; protein-lipid interaction (bovine mitochondria)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The temperature dependence of the oligomycin-sensitive ATPase (complex V) kinetic parameters has been investigated in enzyme preparations of different phospholipid composition. In submitochondrial particles, isolated complex V, and complex V reconstituted in dimirystoyl lecithin vesicles, the Arrhenius plots show discontinuities in the range 18–28°C, while no discontinuity is detected with dioleoyl lecithin recombinant. Van't Hoff plots ofK m also show breaks in the same temperature interval, with the exception of the dioleoylenzyme vesicles, whereK m is unchanged. Thermodynamic analysis of the ATPase reaction shows that DMPC-complex V has rather larger values of activation enthalpy and activation entropy below the transition temperature (24°C) than those of the other preparations, while all enzyme preparations show similar free energies of activation (14.3–18.5 kcal/mol). The results indicate that temperature and lipid composition influence to a different extent both kinetic and thermodynamic parameters of ATP hydrolysis catalyzed by the mitochondrial ATPase.
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    The role of the adenine nucleotide translocator in oxidative phosphorylation. A theoretical investigation on the basis of a comprehensive rate law of the translocator (1982)
    Springer
    Journal of bioenergetics and biomembranes 14 (1982), S. 45-61 
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    ISSN: 1573-6881
    Keywords: Mitochondria ; adenine nucleotide translocator ; kinetics ; metabolic control ; oxidative phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract A minimum model of adenine nucleotide exchange through the inner membrane of mitochondria is presented. The model is based on a sequential mechanism, which presumes ternary complexes formed by binding of metabolites from both sides of the membrane. The model explains the asymmetric kinetics of ADP-ATP exchange as a consequence of its electrogenic character. In energized mitochondria, a part of the membrane potential suppresses the binding of extramitochondrial ATP in competition with ADP. The remaining part of the potential difference inhibits the back exchange of internal ADP for external ATP. The assumption of particular energy-dependent conformational states of the translocator is not necessary. The model is not only compatible with the kinetic properties reported in the literature about the adenine nucleotide exchange, but it also correctly describes the response of mitochondrial respiration to the extramitochondrial ATP/ADP ratio under different conditions. The model computations reveal that the translocation step requires some loss of free energy as driving force. The size of the driving force depends on the flux rate as well as on the extra- and intramitochondrial ATP/ADP quotients. By both quotients the translocator controls the export of ATP formed by oxidative phosphorylation in mitochondria.
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    The effect of cAMP-dependent protein kinase phosphorylation on the external Ca2+ binding sites of cardiac sarcoplasmic reticulum (1983)
    Springer
    Journal of bioenergetics and biomembranes 15 (1983), S. 179-194 
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    ISSN: 1573-6881
    Keywords: Ca2+ binding ; Ca2+-Mg2+-ATPase ; sarcoplasmic reticulum ; cAMP ; protein kinase ; cooperativity ; cardiac muscle ; membrane protein ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Canine cardiac sarcoplasmic reticulum (SR) is known to be phosphorylated by adenosine 3′,5′-monophosphate (cAMP)-dependent protein kinase on a 22,000-dalton protein, Phosphorylation is associated with an increase in both the initial rate of Ca2+ uptake and the Ca2+-ATPase activity which is partially due to an increase in the affinity of the Ca2+-Mg2+-ATPase (E) of sarcoplasmic reticulum for calcium. In this study, the effect of cAMP-dependent protein kinase phosphorylation on the binding of calcium to the SR and on the dissociation of calcium from the SR was examined. The rate of dissociation of the E·Ca2 was measured directly and was not found to be significantly altered by cAMP-dependent protein kinase phosphorylation. Since the affinity of the enzyme for Ca2+ is equal to the ratio of the on and off rates of calcium, these results demonstrate that the observed change in affinity must be due to an increase in the rate of calcium binding to the Ca2+-Mg2+-ATPase of SR. In addition, an increase in the degree of positive cooperativity between the two calcium binding sites was associated with protein kinase phosphorylation.
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    Thermo-elasticity of networks (1982)
    Springer
    Colloid & polymer science 260 (1982), S. 895-910 
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    ISSN: 1435-1536
    Keywords: networks ; thermo-elasticity ; van der Waals equation of state ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Molecular networks may be considered as elastic fluids the conformational abilities of which are adequately characterized with the aid of the model of a van der Waals conformational gas with weak interactions. The internal properties are submitted to the conditions of internal equilibrium, thus, having their changes uniquely related to the global transformations of the network upon deformation. These global properties are at least determining the limits of stability which are expressed in the van der Waals approach by formulating of a reduced equation of state of real networks. It will be discussed on hand of thermo-elastic measurements and its quantitative description what is in need for a full and self-containing phenomenological description of molecular networks.
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    Behaviour of double emulsions in shear flows (1982)
    Springer
    Rheologica acta 21 (1982), S. 593-597 
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    ISSN: 1435-1528
    Keywords: Shear deformation ; stability ; heterogeneous drop ; liquid membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The stability behaviour of heterogeneous drops indicates that, for liquid-liquid dispersions, we may have to modify the stability criterion to incorporate either the rheological characteristics of the dispersion or its cohesion or both.
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    Rheology of coal suspensions (1983)
    Springer
    Rheologica acta 22 (1983), S. 500-504 
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    ISSN: 1435-1528
    Keywords: Coal suspension ; shear dependence ; solid phase concentration ; dispersing medium ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Proper design of operations encountered in preparation, transport and employment of suspensions like coal slurries and coal-oil mixtures require an accurate knowledge of their rheological behaviour. Such concentrated suspensions generally exhibit non-Newtonian behaviour (shearthinning) which is more pronounced at higher coal concentrations. The nature of the dispersing medium influences the aggregation state of the disperse phase and, consequently, affects the stability and the rheology of the systems. In the present paper coal suspensions prepared with different dispersing media and covering a wide range in solid phase concentration are studied, by using a rotational coaxial cylinders viscometer. Different models have been taken into consideration for correlating experimental data. In particular, in order to describe the dependence of viscosity on shear rate and solid phase concentration, the suitability of the model suggested by Smith and Bruce is evaluated. Accordingly, the aggregation state of the disperse phase as well as its dependence on shear rate and dispersing medium can be estimated.
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    Kinetic studies of SF6 plasmas during etching of Si (1983)
    Springer
    Plasma chemistry and plasma processing 3 (1983), S. 329-336 
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    ISSN: 1572-8986
    Keywords: SF6 ; Si ; dc plasma ; etching ; kinetics ; transients ; mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Mass spectrometric kinetic measurements were performed on a dc plasma during the etching of Si by SF6. Neutral plasma particles were permitted to effuse through an aperture in the cathode, via a differentially pumped section, into the ion source of the spectrometer, the sample being mounted on the cathode. The applied voltage was changed in steps, and the resulting mass signal transients for SF x + (x=0−5), F+, S2F 2 + , SiF+, and SiF 3 + were recorded. The SF 5 + , SF 4 + , and SF 3 + signals turned out to be essentially a measure of the unfragmented SF6 present in the plasma, while SF 2 + and SF+ responded in a complex way to the changes of applied voltage. The rate of SiF4 formation was not proportional to the concentration of F atoms or ions present. The S2F2 present in the plasma was probably formed from SF2 and SF radicals, mostly. Slow changes were observed in the signals representing SF 2 + , SF+, S+, F+, and S2F 2 + , presumably related to, or controlled by, gradual changes of the surface undergoing etching. The production and consumption rates of various species were seen to be nearly in balance, and strongly dependent on the applied voltage.
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    Kinetic studies on CF4 plasmas during etching of Si (1983)
    Springer
    Plasma chemistry and plasma processing 3 (1983), S. 337-342 
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    ISSN: 1572-8986
    Keywords: Si ; CF4 ; etching ; dc plasma ; transients ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Mass spectrometric kinetic measurements were performed on a dc plasma during the etching of Si by CF4. The apparatus and procedures used were identical to those developed and used in an earlier study dealing with the Si/SF6 system. The signals representative of CF 3 + , CF 2 + , CF+, F+, SiF 3 + , SiF+, and C2F 5 + were studied in some detail. CF 3 + and CF 2 + transients produced by stepwise changes of the applied voltage were found to be very similar, on a fractional basis. CF+ and C2F 5 + signals showed a close correlation, while the F+ signals indicated a small amount of extra fluorine atoms or ions to be present at relatively high applied voltages. The initial transient rates, following plasma ignition, tended to be slower than those obtained at the higher applied voltages, so the sample surface is somehow etched more rapidly after the first few seconds. In contrast to this, slow signal changes of the sort observed in the Si/SF6 system were absent, so the carbonaceous layers which may form on the Si sample surface appear to adjust rapidly to composition changes in the plasma.
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    Ising-like field theory (1981)
    Springer
    Journal of statistical physics 25 (1981), S. 143-152 
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    ISSN: 1572-9613
    Keywords: Ising model ; field theory model ; stability ; pressure ; ultraviolet divergence ; infrared divergence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A field theory model onR 2 in which the basic fields are Ising spins instead of Gaussian spins is examined. Using statistical mechanics techniques we discuss the ultraviolet and the infrared problems. In particular we discuss a technique yielding the asymptotic expansion in λ of the ground state energy, as λ→0, without using the cluster expansion.
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    Equal-time second-order moments of a harmonic oscillator with stochastic frequency and driving force (1980)
    Springer
    Journal of statistical physics 23 (1980), S. 755-765 
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    ISSN: 1572-9613
    Keywords: Harmonic oscillator ; stochastic frequency ; stochastic differential equation ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using a simple matrix method, we have obtained exact second-order equilibrium moments for a linearly damped harmonic oscillator with a fluctuating frequency ω(t) and driven by a fluctuating forcef(t). We have assumed each of the fluctuating quantities to be delta-correlated. We demonstrate that the final answers are identical whetherf(t) and ω(t) are statistically independent or delta-correlated. We have also established the region of parameter space in which the oscillator is energetically stable. The results are shown to be completely determined by the coefficients of the first and second cumulants of the fluctuations.
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    Agricultural resource use in an andean coastal ecosystem (1981)
    Springer
    Human ecology 9 (1981), S. 47-78 
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    ISSN: 1572-9915
    Keywords: variation ; management ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Ethnic Sciences
    Notes: Abstract Five concurrent systems of agricultural resource management in the Viru Valley in Peru's arid northern coastal plain are discussed as adjustments to microenvironmental variations in soil humidity. Widespread dependence on canal irrigation in an environment characterized by uncertainty in the availability of river water affects the agrarian population in several ways. The upper socioeconomic class has adapted to uncertainty by implementing a deviation-counteracting mechanism (tubular wells) that provides water on demand, giving them flexibility in choice of agricultural activities. Another class of farmers is unable to introduce this mechanism, however, and consequently must depend on a repertoire of inflexible decisions to cope with uncertainty. Each group exploits different opportunity costs to increase economic gain. One pattern provides for expansion, whereas the other at best establishes stability and maintenance. Noncanal techniques permit expansion of cultivation in conditions where canal irrigation is not feasible, thereby improving the overall level of effectiveness of resource use. Alternative techniques do not involve regulatory mechanisms nor do they require complex, interlocking social, economic, and political components. Their presence and persistence in the agricultural system provide variation that may ultimately be amplified as the need to intensify resource exploitation increases in the future.
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    Progressive contextualization: Methods for research in human ecology (1983)
    Springer
    Human ecology 11 (1983), S. 265-281 
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    ISSN: 1572-9915
    Keywords: human ecology research methods ; systems analyses ; people-forest interactions ; flux ; stability ; Man and the Biosphere (MAB) program ; Kalimantan (Borneo)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Ethnic Sciences
    Notes: Abstract Theoretically or practically significant research results concerning transitory as well as persistent phenomena can be obtained by human ecologists while avoiding commitment to long-term, expensive projects, rigid frameworks, traditional disciplinary goals, and unwarranted assumptions about the stability and purposiveness of units or systems. The procedures to be followed, as illustrated by research on people-forest interactions in East Kalimantan, involve a focus on significant human activities or people-environment interactions and the explanation of these by their placement within progressively wider or denser contexts. Guides for progressively contextualizing activities or interactions include a rationality principle, comparative knowledge of contexts, and the principle of pursuing the surprising.
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    The response of a harpacticoid copepod community to sediment disturbance in a semi-enclosed lagoon (1984)
    Springer
    Hydrobiologia 118 (1984), S. 127-133 
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    ISSN: 1573-5117
    Keywords: meiofauna ; Harpacticoida ; eutrophication ; stability ; colonisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The harpacticoid fauna of a sandy sediment in the Sluice Dock of Ostend, Belgium, was dominated by a single species, Canuella perplexa, that attained an average annual density of over 400 ind. 10 cm−2 in 1976 and 1977, whereas other species had a total mean density of less than 10 ind. 10 cm−2. In the summer of 1979 a dystrophic crisis with abundant growth of Ulva occurred and in March 1980 the lagoon was drained. After refilling of the lagoon, the sediment was immediately colonized by good swimming harpacticoids, that attained densities of 200 ind. 10 cm−2. Three months after refilling Canuella perplexa reappeared and the system returned to its original state within one month.
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    Evolutionarily persistent and evolutionarily stable strategies in plant pathosystems (1982)
    Springer
    Euphytica 31 (1982), S. 837-845 
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    ISSN: 1573-5060
    Keywords: Evolutionarily persistent strategies ; evolutionarily stable strategies ; expansive energy ; game theory ; gene-for-gene game ; gene-for-gene relationship ; group selection ; pathosystem fitness ; persistence ; plant pathosystems ; resilience ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Using gene-for-gene relationships as a basis for comparison, I show that Robinson's (1979, 1980) concept of an evolutionarily stable strategy, or ESS for short, is very different from the original definition of Maynard Smith & Price (1973) and, in fact, contradicts it in a number of important respects. The notion of an evolutionarily persistent strategy, or EPS for short, is introduced to clarify these differences and to reduce the potential for confusion in the future. The EPS concept is developed in terms of Holling's (1973) concept of resilience and Van Valen's (1976) notion of expansive energy. The combination of an ESS (sensu Maynard Smith & Price, 1973) and an EPS is offered as an alternative to Robinson's (1979, 1980) ESS concept. Robinson's recommendations for a holistic approach to plant pathosystem management are supported.
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    Limnology and performance of waste treatment lagoons (1980)
    Springer
    Hydrobiologia 72 (1980), S. 21-30 
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    ISSN: 1573-5117
    Keywords: Sewage ponds ; BOD-removal ; stability ; Daphnia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By arranging sewage ponds in series, some feedback relationships within the food web are disconnected, but stability may increase. This particularly applies to a persistent ‘clearwater-state’ in the last cell caused by mass growths of Daphnia or other zooplankton in the absence of fish. Microbial pollution in this case is reduced to a level which may permit nearly unrestricted irrigation. The oxygen balance of lagoons is, apart from the diurnal cycle, subject to substantial temporal variations. This also applies to continuous-flow laboratory models with a constant (BOD-load, temperature) or a constant-cycle (light) chemical and physical environment. An example is given illustrating a high adjustment stability of a lagoon in consequence of a catastrophic perturbation. The strong tendency of lagoons towards an oligomictic behaviour is promoted by thermal stratification and by a vertical gradient in the metabolic activity (oxidation/reduction potential). The hydrodynamic conditions oscillate between plug flow in periods of convective overturn and short-circuiting if thermal stratification has developed. Nevertheless, the average performance (BOD removal) for a particular season could be calculated with a reasonable accuracy. As a basis for this calculation, nomographs were developed from which the rate coefficient K1 of BOD removal for a given combination of residence time and BOD load can be read.
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    A comparative study of the sessile, filter-feeding ciliates of several small streams (1983)
    Springer
    Hydrobiologia 98 (1983), S. 125-133 
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    ISSN: 1573-5117
    Keywords: peritrichs ; ciliates ; streams ; aufwuchs ; stability ; diversity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Artificial substrates, consisting of strips of nylon cloth, were used to sample sessile, filter-feeding ciliates at eleven stream sites. These ciliates were common (61 % of samples) and frequently abundant (mean = 95 cm−2). Populations varied widely, even within stream sites, and mean abundance was not related to subjective assessments of the sites. Permanent rural streams and streams below reservoirs, which have relatively stable flow regimes, had a peritrich fauna dominated byVorticella campanula along withCarchesium polypinum andV. striata. Urban and intermittent streams, with less stable flow regimes, showed an increasing number of peritrichs with non-contractile stalks, particularlyEpistylis plicatilis. The commonness and diversity of peritrichs was positively related to aufwuchs stability.
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    Method of reduction in convex programming (1983)
    Springer
    Journal of optimization theory and applications 40 (1983), S. 349-378 
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    ISSN: 1573-2878
    Keywords: Convexity ; subdifferentials ; cones of directions of constancy ; equality set of constraints ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We present an algorithm which solves a convex program with faithfully convex (not necessarily differentiable) constraints. While finding a feasible starting point, the algorithm reduces the program to an equivalent program for which Slater's condition is satisfied. Included are algorithms for calculating various objects which have recently appeared in the literature. Stability of the algorithm is discussed.
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    Stability of nondominated solutions in multicriteria decision-making (1980)
    Springer
    Journal of optimization theory and applications 30 (1980), S. 229-253 
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    ISSN: 1573-2878
    Keywords: Point-to-set maps ; domination structures ; parameterized decision-making problems ; solution maps ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Decision-making problems with multiple noncommensurable objectives are specified by two factors, i.e., the set of all feasible solutions and the domination structure. The solutions are characterized as nondominated points. Hence, in these problems, there may exist two parameter vectors, according to which the above two factors change. The stability of the solution set for perturbations of these parameters is investigated in this paper. The analysis is guided by using the concept of continuity of the solution map defined on the two parameter spaces.
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    Existence and global asymptotic stability of optimal trajectories for a class of infinite-horizon, nonconvex systems (1980)
    Springer
    Journal of optimization theory and applications 31 (1980), S. 515-533 
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    ISSN: 1573-2878
    Keywords: Optimal control ; economic systems ; stability ; existence theory ; turnpike property
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Sufficient conditions for the existence of optimal trajectories and for the global asymptotic stability of these trajectories are given for a class of nonconvex and nonautonomous systems controlled over an infinite-time horizon. The concept ofG-supported trajectory is introduced. It is shown that, under some assumptions, aG-supported trajectory is overtaking and is globally asymptotically stable. The concept of overtaking trajectory has been previously defined as a notion of optimality on an infinite-time domain. For autonomous systems, under weaker conditions, one guarantees the existence of weakly overtaking trajectories. Finally, it is shown howG-supported trajectories can be obtained, and an application to the study of a pre-predator ecosystem optimally harvested is sketched.
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    Stability of compromise solution in multicriteria decision-making problems (1983)
    Springer
    Journal of optimization theory and applications 40 (1983), S. 77-83 
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    ISSN: 1573-2878
    Keywords: Parameterized decision-making problems ; utopia point ; compromise solutions ; Hausdorff distance ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Stability is a desirable attribute of the nondominated solution in the decision-making problem with multiple noncommensurable objectives. It is assumed that the decision space is given by a system of inequalitiesG(x)≤b, b ∈ R N . In this paper, sufficient conditions are determined for a compromise solution to be stable with respect to the changes ofb.
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    Stochastic scheduling problems I — General strategies (1984)
    Springer
    Mathematical methods of operations research 28 (1984), S. 193-260 
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    ISSN: 1432-5217
    Keywords: Analytic behaviour of strategies ; continuous strategies ; ES strategies ; MES strategies ; machine idleness ; monotonicity behaviour ; optimal strategies ; preselectivity ; regular measure of performance ; scheduling problems ; stability ; stochastic dynamic optimization ; stochastically ordered distributions ; stochastic scheduling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract The paper contains an introduction to recent developments in the theory of non-preemptive stochastic scheduling problems. The topics covered are: arbitrary joint distributions of activity durations, arbitrary regular measures of performance and arbitrary precedence and resource constraints. The possible instability of the problem is demonstrated and hints are given on stable classes of strategies available, including the combinatorial vs. analytical characterization of such classes. Given this background, the main emphasis of the paper is on the monotonicity behaviour of the model and on the existence of optimal strategies. Existing results are presented and generalized, in particular w.r.t. the cases of lower semicontinuous performance measures or joint duration distributions having a Lebesgue density.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01919323
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  • 98
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    Electronic Resource
    Conflict dissolution by reframing game payoffs using linear perturbations (1983)
    Springer
    Journal of optimization theory and applications 39 (1983), S. 187-214 
    Details
    ISSN: 1573-2878
    Keywords: Self-interest maximization ; self-interest stable solutions ; self-interest cooperative games ; self-interest noncooperative games ; monotonic games ; decomposition theory ; reframing game payoffs ; full cooperation ; targeted solutions ; Pareto optimality ; collective group interest ; stability ; structural departure ; incentives for adopting a new game ; habitual domain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Human beings have a prevailing drive to achieve their self-interest goals or equilibrium states, which may subsume their social interests. An ideal working environment or cooperative game situation would be one in which each participant or player maximizes his/her own interest while maximizing his/her contribution to the collective group interest. This paper addresses the feasibility, methods, and bounds for reframing a generaln-person game into an ideal game in which full cooperation or a targeted solution can be induced and maintained by the players' self-interest maximization. Criteria for good reframing are introduced. Monotonic games, self-interest cooperative and noncooperative games, and a decomposition theory of general games are also introduced to facilitate the study. It is shown that everyn-person game can be written as the sum of a self-interest cooperative game and a self-interest noncooperative game. Everyn-person game can be reframed so that full cooperation can be achieved by the players' self-interest maximization. Everyn-person game can be reframed so that a targeted solution can be obtained and maintained through the players' self-interest maximization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00934528
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  • 99
    Electronic Resource
    Electronic Resource
    Decentralized control with overlapping information sets (1981)
    Springer
    Journal of optimization theory and applications 34 (1981), S. 279-310 
    Details
    ISSN: 1573-2878
    Keywords: Decentralized control ; overlapping decompositions ; suboptimality ; stability ; interconnected power systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract A decentralized control scheme is proposed for linear systems composed of overlapping subsystems. By expanding the state space of the system, a higher-dimensional space is formed where the subsystems appear as disjoint. In the expanded space, standard optimization techniques can be used to formulate a suboptimal decentralized control law for the overall system. A suitable contraction of the obtained control law, which is compatible with the information constraints imposed by the overlapping subsystems, can be implemented in the original system. The application of the proposed decentralized control scheme is illustrated using a 19th order model for load-frequency control of a two-area interconnected power system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00935477
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  • 100
    Electronic Resource
    Electronic Resource
    Contour of complete nonuniqueness as a method of structural optimization with stability constraints (1981)
    Springer
    Journal of optimization theory and applications 35 (1981), S. 23-30 
    Details
    ISSN: 1573-2878
    Keywords: Contour of complete nonuniqueness ; trusses ; stability ; structural optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This paper develops the concept of a contour of complete nonuniqueness and shows its application to the optimal design (optimal layout) of simple trusses transmitting a concentrated force to a presscribed, arbitrary foundation contour. As an example, a symmetric two-bar truss with compressed bars is considered, and the constraints refer to various kinds of elastic instability of the system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00934701
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