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  • Spektralphotometrie  (167)
  • bioavailability  (65)
  • pheromone  (60)
  • oxidation  (57)
  • Springer  (349)
  • American Association for the Advancement of Science
  • Cambridge University Press
  • 1975-1979  (349)
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Verlag/Herausgeber
  • Springer  (349)
  • American Association for the Advancement of Science
  • Cambridge University Press
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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 8 (1975), S. 293-299 
    ISSN: 1432-1041
    Schlagwort(e): Rifampicin ; p-aminosalicylic acid ; bentonite ; drug interaction ; bioavailability ; drug adsorption
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The bioavailability (plasma concentrations, AUC and urinary excretion) of an oral solution of rifampicin was investigated in six healthy volunteers. Simultaneous administration of PAS granules produced a significant decrease in the absorption of RMP, whereas Na-PAS tablets had no effect. This indicated that the dosage form of the granules and not PAS itself was responsible for the interaction, and that the dissolution of RMP was not involved. The interaction could be reproduced by giving dummy granules that contained the same excipients but no PAS. The disintegration and dissolution of PAS granulesin vitro correlated well with the disappearance of RMP from the solution. The major excipient of the granules, bentonite (a mineral closely related to kaolin), was found to adsorb rifampicin rapidly and strongly.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 8 (1975), S. 365-370 
    ISSN: 1432-1041
    Schlagwort(e): Particle size ; bioavailability ; digoxin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The bioavailability of digoxin in three tablets prepared from materials with different particle sizes was measured in healthy volunteers in a cross-over study using an alcoholic solution of digoxin as a reference standard. Its bioavailability in tablets with particle sizes of 7 µ or 13 µ was 78–97% of that of digoxin in solution. The tablet with largest particle size (102 µ) showed markedly lower bioavailability than the reference solution, namely 39%. It is obvious that particle size is an important determinant of the dissolution rate and bioavailability of digoxin.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 9 (1975), S. 209-212 
    ISSN: 1432-1041
    Schlagwort(e): Anticonvulsants ; phenytoin ; diphenylhydantoin ; bioavailability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Plasma phenytoin levels were measured in 60 patients under steady-state conditions for a period of six weeks. During the trial, the preparation of phenytoin was changed from Phenytoin BP (Regent) to Epanutin Infatabs. A significant increase in plasma phenytoin levels following the change of tablet was matched by a decrease in the number of seizures.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 9 (1975), S. 213-218 
    ISSN: 1432-1041
    Schlagwort(e): Phenytoin ; diphenylhydantoin ; anticonvulsants ; bioavailability ; drug absorption ; generic inequivalence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary In order to evaluate the bioavailability of four different brands of phenytoin (diphenylhydantoin, DPH) tablets single doses of 600 mg DPH in acid form were given to six volunteers in a cross-over study. A micronized DPH-acid suspension was used as the reference standard. Significant differences between various products were found. The areas under the serum DPH concentration-time curves (AUC) were 26, 59, 68 and 90 per cent of the AUC of the DPH suspension. The peak serum DPH concentrations using the different tablets were 24, 54, 55 and 80 per cent of the peak value of the DPH suspension. It is likely that the differences in bio-availability of the DPH tablets are of clinical significance.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 9 (1976), S. 315-317 
    ISSN: 1432-1041
    Schlagwort(e): Tolamolol ; bioavailability ; maximum exercise tachycardia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Bioavailability of capsule and tablet formulations of tolamolol were compared by measuring plasma concentration of tolamolol and reduction in maximum exercise heart rate over a period of twelve hours in eight healthy subjects in a two-way cross-over study. Tolamol was absorbed more rapidly from capsules than from tablets; this did not result in any significant difference in the reduction in maximum exercise heart rate between the two formulations. There was no significant difference between area under curve of reduction in exercise tachycardia and area under curve of plasma concentration of tolamolol for the two formulations. Reduction in maximum exercise heart rate was related to logarithm of plasma concentration of tolamolol between two and twelve hours after both formulations.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 9 (1976), S. 373-379 
    ISSN: 1432-1041
    Schlagwort(e): Methyldigoxin ; repetitive doses ; bioavailability ; deep compartments ; oral and i.v. dose ; volunteers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary To obtain true half lives, glycoside elimination from six healthy subjects was studied for 14 days after multiple intravenous doses or oral administration of a daily maintenance dose of β-methyldigoxin 0.3 mg. After oral or intravenous administration of β-methyldigoxin ceased, the plasma concentrations declined from the 14th to the 16th days with a half life of 1.7 days. From the 16th to the 20th day a change from a shorter to a longer half life of 2.8 and 2.9 days was observed. Similar half lives were found in urine: after the last dose the initial slope from the 14th to the 16th day had a half life of 1.8 days, and the terminal slope had one of 3.2 days. The results indicate release of the glycoside from slowly equilibrating tissues.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 8 (1975), S. 371-376 
    ISSN: 1432-1041
    Schlagwort(e): Digoxin ; bioavailability ; plasma levels ; cumulative urinary excretion ; particle size ; man
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Various brands of digoxin tablets, and even different batches of one brand, may differ greatly in bioavailability. Digoxin-Sandoz® tablets have been compared with Lanoxin® manufactured between 1969 and 1972 and after May 1972. Comparisons were also made between and within batches of Digoxin-Sandoz tablets. Three separate cross-over studies were conducted involving a total of 20 volunteers. Digoxin-Sandoz tablets were shown to have a constant bioavailability and to produce plasma concentrations very similar to “new” Lanoxin. Storage for 2 years of one batch of Digoxin-Sandoz did not alter the bioavailability. Particle size was shown to influence bioavailability. Care should be exercised when plasma data alone are interpreted as an index of bioavailability. Measures of bioavailability based on plasma data obtained up to 6 h after administration differed from those based on cumulative urinary excretion data (in this study by a factor of about 2), which can lead to the belief that a difference in bioavailability is much greater than is actually the case. Data from cumulative urinary excretion, collected over a sufficiently long period of time, are likely to be the most reliable method for determining the bioavailability of a substance such as digoxin.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 16 (1979), S. 211-215 
    ISSN: 1432-1041
    Schlagwort(e): fluoride ; bioavailability ; calcium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The effect of milk products on the gastrointestinal absorption of fluoride from sodium fluoride tablets was studied in five healthy subjects. Two different diets were tested: (1) 250 ml standardized milk (3% fat) and (2) 500 ml of milk, 3 pieces of white bread with cheese and 150 ml of yoghurt. The 100% bioavailability of sodium fluoride tablets during fasting was greatly decreased by coadministration of milk products: with Diet 1 the absolute bioavailability calculated from combined plasma and urine data was in the range 50–79% and with Diet 2 it ranged from 50–71%. It is suggested that the decreased bioavailability produced by dairy products should be taken into account when establishing fluoride dosage regimens for prophylaxis of caries.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 10 (1976), S. 231-236 
    ISSN: 1432-1041
    Schlagwort(e): Digoxin ; beta-methyl-digoxin ; capsules ; bioavailability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The intestinal absorption and urinary elimination rate of total cardioactive material was compared following digoxin and beta-methyldigoxin (BMD) administration to twelve healthy volunteers. Significantly more injected digoxin was recovered in urine. Urinary clearance was more rapid for digoxin, mean half-lives of elimination being 35 hours for digoxin and 40 hours for BMD. Calculated percentage intestinal absorption was lowest for digoxin tablets with a dissolution rate of 77% in one hour, intermediate for BMD tablets, and maximal for an experimental soft gelatin formulation of digoxin in solution. Respective mean values were 75%, 87% and 97%. Similar steady state plasma concentrations followed twice daily ingestion of the 0.25 mg digoxin tablets and 0.20 mg BMD tablets. Mean peak plasma concentration and percentage urinary recovery of ingested dose were higher during continued BMD administration. Between-subject variation in absorption was higher for the digoxin tablets. The comparative intestinal absorption of BMD and digoxin depends upon the formulation. Digoxin is virtually completely absorbed from a solution encapsulated in soft gelatin. Relatively more BMD is eliminated by nonrenal routes.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 10 (1976), S. 251-256 
    ISSN: 1432-1041
    Schlagwort(e): Sisomicin ; pharmacokinetics ; bioavailability ; two-compartment analysis ; man
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetics of sisomicin, a new single component aminoglycoside antibiotic related to gentamicin c1a, were determined in four healthy volunteers after intravenous and intramuscular administration of a 1 mg/kg dose. The elimination profile of this antibiotic follows two-compartment model kinetics after I.V. administration. The fast (α) and slow (β) disposition rate constants averaged 0.072 and 0.004 min−1, respectively. The volume of distribution at the steady-state averaged 0.185 liters/kg which approximately corresponds to the volume of extracellular space. The physiological availability of an intramuscular dose appeared to be complete. A method of administration adapted to the kinetic properties of the drug is proposed.
    Materialart: Digitale Medien
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  • 11
    ISSN: 1432-1041
    Schlagwort(e): Cefoxitin ; lidocaine ; intramuscular ; bioavailability ; pain
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The use of lidocaine HCl solution at concentrations of 0.5 and 1.0% to reconstitute sodium cefoxitin relieves the pain associated with intramuscular injections of the antibiotic. Cefoxitin absorption by the intramuscular route is initially rapid and is virtually complete. Peak serum concentrations, corresponding to about one-half those of a comparable intravenous infusion, are achieved in 30 min. Continuing absorption tends to maintain higher serum concentrations for longer times. Renal clearance and serum half-life of cefoxitin do not appear to be affected by lidocaine at its effective anaesthetic concentrations.
    Materialart: Digitale Medien
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 13 (1978), S. 49-53 
    ISSN: 1432-1041
    Schlagwort(e): p-Chlorophenoxyisobutyric acid ; clofibrate ; steady-state plasma concentrations ; bioavailability ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Plasma concentrations and bioavailability of clofibrinic acid have been estimated under conditions approaching the steady-state during a ten-day period of administration as clofibrate or as a calcium clofibrinate-carbonate combination (1:1 w/w) at a dosage interval of 12 h. Formulation — related differences in bioavailability were not significant, and the 95% confidence limits of these differences were within −2% to +8% of the mean for the reference formulation of clofibrate. The mean steadystate plasma concentrations of clofibrinic acid measured on the tenth day of dosing were 116 µg/ml±22 S.D. and 119 µg/ml±23 S.D. after administration of 885 mg as clofibrate and the calcium clofibrinate-carbonate combination respectively. The peaks of mean plasma concentrations were 70 µg/ml±15 S.D., 119 µg/ml±32 S.D. and 131 µg/ml±26 S.D. on the first, fifth and tenth day of dosing with clofibrate, and 62 µg/ml±13 S.D., 127 µg/ml±S.D. and 143 µg/ml±25 S.D. on the corresponding days of dosing with the calcium clofibrinate-carbonate combination. After the last dose on the tenth day of dosing, the mean apparent half-lives of elimination of clofibrinic acid from plasma were 24.2 h±4.4 S.D. and 25.5 h±3.2 S.D. after administration of clofibrate and the calcium clofibrinate-carbonate combination respectively.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 13 (1978), S. 125-128 
    ISSN: 1432-1041
    Schlagwort(e): bioavailability ; diuretics ; gastrointestinal absorption ; hydrochlorothiazide ; thiazides ; food effect
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Hydrochlorothiazide (hct) 75 mg was administered orally to eight healthy volunteers without (Study I) or together with a standardized meal (Study II), and plasma and urine concentrations of hct were analyzed by GLC. The plasma levels of hct were higher initially when the tablets were taken on an empty stomach, but after 5 h they were higher in Study II. There was no difference between the two studies in the area under plasma concentration time curves. The urinary recovery of hct totalled 55.6±4.9 mg when the drug was given with food and 47.4±6.0 when it was taken on an empty stomach. The difference is significant (p〈0.01). As the urinary recovery represents the uptake of hct, it appears that the gastrointestinal absorption of hct is enhanced when the drug is given with food.
    Materialart: Digitale Medien
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 10 (1976), S. 257-262 
    ISSN: 1432-1041
    Schlagwort(e): Anti-inflammatory and analgesic drug ; indoprofen ; pharmacokinetics ; bioavailability ; man
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary In a pharmacokinetic study of the new analgesic and anti-inflammatory drug indoprofen, plasma levels and urinary excretion were determined in four healthy volunteers after 100 mg and 200 mg iv, and after 100 mg (capsules) and 200 mg (tablets) oral doses. After iv administration, the mean biological half-life (t1/2 β) was about 2 h (range 1.4 to 3.2 h). The apparent volume of distribution Vdβ ranged between 11 to 17 % of body weight, indicating its limited extravascular distribution. Most of the drug was excreted in urine as glucuronide and a smaller proportion as unchanged indoprofen: the 24 h urinary excretion of these compounds accounted for 67 to 95 % of an iv dose. Peak plasma levels occurred between 30 and 120 minutes after oral administration of 100 mg as capsules or 200 mg as tablets. The mean biological half-life was about 2 h, as after iv administration. The bioavailability of oral doses was assessed using both plasma levels and urinary excretion data. The absorption of capsules and tablets was practically complete, that of the former being faster.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 10 (1976), S. 101-108 
    ISSN: 1432-1041
    Schlagwort(e): Cardiac glycosides ; methyl proscillaridin ; plasma concentrations ; electrocardiogram ; bioavailability ; 86Rb-erythrocyte assay
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The aim of this study was to obtain data about the pharmacological properties of a new glycoside derivative in man. Plasma concentrations and ECG parameters were measured after oral and intravenous administration of a single dose of 1.2 mg methyl proscillaridin in 16 healthy volunteers, using a strictly randomized, two-period change-over design. Glycoside concentrations were measured using a modified86Rb-erythrocyte-assay. QT-duration, corrected for frequency (QTc), was the principal variable measured in the ECG. By either route, there was a maximum plasma level after 1 hour, which had decreased to a minimum at 3 hours, followed by a second peak at 4 to 10 hours (orally〉iv). From 10 to 72 hours the concentrations decreased with a median t 1/2 of 23.3 hours (iv) and 33.0 hours (orally). Comparison of the ratio of plasma concentrations following oral and iv administration resulted in a bioavailability of 69 % using the 48 hour plasma levels, and 59 % using the areas under the concentration-time curves. The mean QTc was maximally shortened to 28 msec at 1 hour after iv and to 19 msec at 10 hours after the oral dose. A distinct similarity between time-concentration and time-QTc curves was seen after the initial distribution phase, both after oral and intravenous administration. The new derivative shows a rapid elimination. Its bioavailability is reasonably high.
    Materialart: Digitale Medien
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 16 (1979), S. 417-421 
    ISSN: 1432-1041
    Schlagwort(e): theophylline ; aminophylline ; bioavailability ; rapidly dissolving tablet
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The bioavailability of a rapidly dissolving tablet of theophylline and three brands of standard aminophylline tablets was estimated in a four way cross-over study involving 8 healthy adult volunteers. The relative extent of bioavailability as assessed by the measurement of the total area under the plasma concentration time curves showed no difference between the products (P〉0.05). Computed estimates of the rate of drug absorption were similar for all 4 products tested. The results indicate that the rapidly dissolving tablet offers no advantage in respect to rate and extent of absorption over conventional aminophylline tablets.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 12 (1977), S. 69-72 
    ISSN: 1432-1041
    Schlagwort(e): Metronidazole ; serum concentration ; bioavailability ; food intake ; healthy subjects ; Crohn's disease
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The possible influence of food intake on the bioavailability of metronidazole was examined in ten healthy volunteers by administration of a single dose of metronidazole on an empty stomach, and with a standardized breakfast. Food intake did not significantly alter the bioavailability of metronidazole. The interindividual variation in bioavailability appeared to be slight. In nine patients with Crohn's disease, the absorption of metronidazole appeared to be reduced and to be more variable than in healthy subjects. In both groups there was a clear relationship between the amount absorbed and dose/kg body weight. Thus, from the pharmacokinetic point of view, metronidazole can safely be given either with or between meals. The dose should be related to body weight.
    Materialart: Digitale Medien
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 12 (1977), S. 285-290 
    ISSN: 1432-1041
    Schlagwort(e): Phenytoin acid ; phenytoin calcium ; bioavailability ; inequivalence of generics ; normal subjects ; volunteers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Serum phenytoin concentrations have been studied in epileptic patients and healthy subjects taking tablets of phenytoin calcium (Desitin), A, phenytoin acid (Desitin), B, and phenytoin acid (Nordmark), C. Retrospective data and prospective investigation of hospitalized patients on long-term phenytoin treatment showed that significantly higher serum concentrations of phenytoin were produced by the phenytoin acid preparations B and C than by the phenytoin calcium preparation A. In a cross over study six volunteers received 200 mg/day of preparations A, B, and C for three weeks. In this study, too, higher phenytoin serum concentrations were produced by B and C than by A, although the differences were not statistically significant. The reasons for the discrepancies between the studies in healthy and epileptic subjects are discussed.
    Materialart: Digitale Medien
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 12 (1977), S. 383-386 
    ISSN: 1432-1041
    Schlagwort(e): Benzodiazepine ; temazepam ; pharmacokinetics ; bioavailability ; hard and soft gelatine capsules
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Plasma levels of temazepam were determined in healthy subjects after single oral administration of soft and hard gelatin capsules, and after 7 consecutive night-time doses in soft capsules. Absorption from soft gelatin capsules was significantly faster and produced earlier and higher peak plasma levels. The two pharmaceutical forms did not show any significant difference in relative availability. The apparent half-life of temazepam after night-time administration was significantly shorter than after morning administration, but no change in half-life was observed between the first and seventh night-time doses.
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 14 (1978), S. 253-259 
    ISSN: 1432-1041
    Schlagwort(e): Pseudoephedrine ; side effects ; bioavailability ; multiple oral dosing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Dose tolerance and pharmacokinetic studies of pseudoephedrine sustained action capsules were performed in thirty-three adult male subjects who received either 120 mg or 150 mg capsules every twelve hours for seven consecutive days in a double-blind parallel design study. Although only one subject in the 150 mg group was discontinued prematurely from this study, a large number of side effects typical of CNS stimulation were seen. A placebo effect might account for a portion of these complaints, however symtoms evaluated as being due to drug were significantly more severe and persistent in the 150 mg group. Pulse rates showed a persistent and significant increase while systolic and diastolic blood pressure fell from the baseline values in both groups. A pharmacokinetic analysis of the pseudoephedrine plasma concentration-time data provided estimates of half-life and the volume of distribution/availability ratio. The values obtained were in good agreement with values reported by others. Half-life was not influenced by urine pH probably as a result of the narrow range of urine pHs observed in the subjects. Calculations of relative bioavailability suggest that the 120 mg capsule formulation has a 30% greater bioavailability compared to the 150 mg capsule.
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  • 21
    ISSN: 1432-1041
    Schlagwort(e): chlorthalidone ; pharmacokinetics ; oral and i.v. doses ; bioavailability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Seven normal human volunteers each received a constant-rate infusion of chlorthalidone for 2 h, and the same (commonly 50 mg) single oral dose on separate occasions. The concentration of unchanged chlorthalidone was analyzed over a 100 to 220 h period in plasma, red blood cells, urine and faeces after both dosage forms. A three compartment model was required to describe the intravenous plasma concentrations in five of the subjects. A two compartment model sufficed to account for the decay of the oral plasma concentrations in all seven subjects. The mean plasma t1/2 after i.v. dosing was 36.5 h (±10.5 SD), and the mean plasma t1/2 after oral doses was 44.1 h (±9.6 SD). The mean red blood cell concentration t1/2 after i.v. doses was 46.4 h (±9.9 SD), and the mean red blood cell t1/2 after the oral doses was 52.7 h (±9.0 SD). The shorter i.v. half-live was not equally manifest in all subjects, being mainly apparent in three of them. In all cases the urinary excretion rate plots were parallel to the plasma concentration curves. As the faster decay after i.v. administration was not accompanied by increased renal clearance, the difference must have been due to non-renal mechanism. The mean total of 65.4 (±8.6 SD) % of the intravenous dose was excreted in urine over infinite time, whereas the mean total excretion after the oral dose was 43.8 (±8.5 SD) %. Faecal excretion ranged from 1.3–8.5% of dose in the i.v. study to 17.5–31.2% of dose in the oral study. The sum of the amounts present in urine plus faeces pointed strongly to an important metabolic route of elimination of chlorthalidone. Bioavailability estimates (F) from three sets of data were — a mean F of 0.61 from plasma concentrations, 0.67 from urinary excretion measurements and 0.72 from the erythrocyte concentrations. Simulations with a non-linear model indicated lesser validity of the estimate from erythrocyte concentrations. It was concluded that the average of plasma and urine data, F=0.64, yielded the best estimate of the oral availability of chlorthalidone 50 mg in man.
    Materialart: Digitale Medien
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 16 (1979), S. 31-38 
    ISSN: 1432-1041
    Schlagwort(e): bezafibrate ; hyperlipoproteinemia ; bioavailability ; pharmacokinetics ; GC-MS
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The disposition kinetics of bezafibrate, a newly developed drug of great lipid-lowering potency, were investigated in normal male subjects. Five male volunteers received14C-labelled bezafibrate orally in solution, and a further 10 were given the same dose (300 mg) of un-labelled drug as tablets. The concentration of bezafibrate in serum and urine from the latter was determined by GC, and in the former total radioactivity in serum, urine and feces was followed for 48 h, and urinary excretion products were analysed by TLC and GC-MS. Rapid absorption from the gastrointestinal tract led to peak serum levels 30 min and 2 h after administration of solution and tablets, respectively. Since approximately 95% of the administered14C-bezafibrate was excreted in urine within 48 h, and almost all the remainder was detected in feces, absorption can be regarded as complete after administration in solution. The relative optimal bioavailability from the tablets was also complete, since in both cases approximately 50% of the administered dose was detected as unchanged bezafibrate in urine within 24 h by GC in the tablet study, and by TLC in the solution study. Of the decomposition products, more than 20% of the dose was present as glucuronides and the remainder consisted of several more polar compounds, one of which was identified as a hydroxyderivative of bezafibrate. Since the apparent halflife of bezafibrate in serum was 2.1 h, this new drug possesses favourable pharmacokinetic features: rapid and complete absorption, even from tablets, combined with a conveniently short half-life, and clearance which is half renal (56 ml/min) and half metabolic (43 ml/min), giving a total clearance of 99 ml/min.
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  • 23
    ISSN: 1432-1041
    Schlagwort(e): indobufen ; platelet aggregation ; single dose ; bioavailability ; pharmacodynamics ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Six healthy volunteers received single iv and oral doses of 2-[p-(1-oxo-2-isoindolinyl)phenyl] butyric acid 100 mg (indobufen; K 3920), an inhibitor of platelet aggregation. Plasma levels and urinary excretion of the drug were determined by GLC. Collagen-induced platelet aggregation was assessed turbidimetrically at various intervals after administration. The plasma half-life of the drug was 7–8 h and more than 70% of the administered dose was recovered within 48 h in urine, as unchanged drug and as the glucuronide of indobufen. After oral administration of tablets of two different formulations, the drug was completely absorbed, but one formulation showed faster absorption. The maximal inhibitory effect on platelet aggregation was observed 1 to 4 h after iv administration, and it had decreased by 8 h. After tablets, peak effect and the time of the peak were similar, but activity was significantly prolonged, in accordance with the higher plasma levels found at 8 h. The data suggest that the effect of indobufen on platelets is reversible, and that for this drug platelets behave as a compartment that slowly equilibrates with plasma.
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  • 24
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 16 (1979), S. 45-48 
    ISSN: 1432-1041
    Schlagwort(e): quinidine ; slow release formulation ; pharmacokinetics ; bioavailability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The bioavailability of quinidine in two sustained release preparations A and B has been compared in three females and three males with i.v. administration of quinidine. The initial rate of oral absorption did not differ between the two drug preparations; the peak concentration was observed after 4 h both for A and B, but was significantly higher after B. A slower decrease in plasma concentration was observed after preparation A than B. Absolute bioavailability did not differ significantly between A (median value 78.4%) and B (median 87.1%). Drug absorption in vivo was in good agreement with the results of in vitro dissolution tests on both preparations. The slower decrease in plasma concentration found for the new sustained release form of quinidine should be of clinical advantage.
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 10 (1976), S. 183-187 
    ISSN: 1432-1041
    Schlagwort(e): Hydralazine ; bioavailability ; pharmacogenetics ; first pass effect ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary After oral administration of a single 50 mg dose of hydralazine (Apresoline®), the serum half-life (T1/2) and bioavailability (AUC0−∞) were assessed in 16 healthy volunteers. The half-life was 2.57±0.14 h (S.E.) in 10 slow acetylators of sulphadimidine, and 2.18±0.15 h in 6 fast acetylators (difference not statistically significant). AUC0−∞ was significantly higher in slow acetylators, at 1.04±0.10 µg·hour·ml−1, compared to 0.66±0.12 µg·hour·ml−1 in the fast acetylators (p〈0.025). Treatment with Apresoline® 25 mg tid produced minimum serum concentrations at steady-state of 57.3±7.3 ng·ml−1 and 33.4±4.2 ng·ml−1 in 8 slow and 5 fast acetylators, respectively (p〈0.05). The corresponding maximum concentrations were 228.8±20.3 ng·ml−1 and 147.6±15.0 ng·ml−1 in slow and fast acetylators, respectively (p〈0.025). First-pass metabolism of hydralazine could explain the difference in bioavailability of the drug between fast and slow acetylators, without any corresponding difference in the elimination rate of the drug in the post-distributive phase.
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 10 (1976), S. 395-401 
    ISSN: 1432-1041
    Schlagwort(e): Hydralazine ; bioavailability ; polymorphic acetylation ; first-pass metabolism ; oral and intravenous dosing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The bioavailability of orally administered hydralazine was assessed in 4 healthy subjects after separate administration of a single oral or intravenous dose (0.3 mg·kg−1). Comparison of the areas under the serum concentration-time curves showed that 26 – 55 % of the oral dose was available to the systemic circulation as unchanged drug. The O - 24 h excretion of the drug in urine was rapid: 11.4 – 14.1 % of the dose after intravenous administration, and 2.0 – 3.6 % after an oral dose. Acetylation of hydralazine leads to formation of 3-methyl-s-triazolo-3,4,a-phthalazine (MTP) and a gas-liquid-chromatographic method for its measurement in urine was developed. After oral and intravenous administration, 0.8 – 1.2 % and 1.4 – 2.3 % of the dose, respectively, were recovered within 24 hours from urine as MTP. After oral administration there was a relative increase in the amount of MTP in every subject, which indicates route-dependent metabolism. The lower bioavailability of oral hydralazine could be explained in terms of first-pass metabolism.
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 16 (1979), S. 335-340 
    ISSN: 1432-1041
    Schlagwort(e): cimetidine ; enterohepatic circulation ; irregular absorption ; bioavailability ; pharmacokinetics ; volunteers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The bioavailability and pharmacokinetics of cimetidine have been studied in healthy volunteers after administration of single intravenous (100 mg) and oral doses (100, 400 and 800 mg). After i.v. administration, the kinetics of cimetidine could be described by a linear, two compartment open model. Substantial variation in half-life was observed between subjects, with a mean value of 2.1 h (range 0.9–4.7). Cimetidine had a low hepatic extraction ratio and a high total plasma clearance, due to extensive urinary excretion of unchanged drug. After oral administration, the plasma concentration vs time curves in most subjects exhibited two marked peaks, an observation that seemed to be constant within individuals and was independent of dose. Bioavailability, estimated as the area under the plasma concentration vs time curves (AUC), after oral doses as compared to the intravenous dose, in most cases exceeded 100%. There was no correlation between bioavailability estimated as AUC and as urinary excretion of unchanged drug. These observations may indicate an enterohepatic circulatory mechanism, predominantly after oral administration. Both unchanged drug and its sulphoxide metabolite appear to be excreted in bile. The latter was shown in vitro to be reduced to cimetidine by fecal bacteria.
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 13 (1978), S. 267-274 
    ISSN: 1432-1041
    Schlagwort(e): Chlordiazepoxide ; benzodiazepines ; pharmacokinetics ; bioavailability ; intramuscular injection ; alcohol withdrawal
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The absorption of oral and intramuscular (i. m.) chlordiazepoxide hydrochloride (CDX · HCl) was compared in two pharmacokinetic studies. In Study One, single 50-mg doses of CDX · HCl were administered orally and by i. m. injection to 14 healthy volunteers using a crossover design. Whole-blood concentrations of chlordiazepoxide (CDX) and its first active metabolite, desmethylchlordiazepoxide (DMCDX), were determined in multiple samples drawn after the dose. Mean pharmacokinetic variables for CDX following oral and i. m. administration, respectively, were: highest measured blood concentration, 1.65 vs 0.87 µg/ml (p〈0.001); time of highest concentration, 2.3 vs 7.6 h after dosing (p〈0.001); apparent absorption half-life, 0.71 vs 3.39 h (p〈0.001). Biphasic absorption after i. m. injection, consistent with precipitation at the injection site, was observed in 9 of 14 subjects. Based upon comparison with previous intravenous data, the completeness of absorption was 100% for oral vs 86% for i. m. CDX · HCl (p〈0.1). In Study Two, 28 male chronic alcoholics with clinical manifestations of the acute alcohol withdrawal syndrome were randomly assigned to one of four treatment conditions: 50 or 100 mg doses of CDX · HCl, by mouth or by i. m. injection. Concentrations of CDX and DMCDX, determined in plasma samples drawn every 20 min for 5 h following the dose, were significantly higher after oral administration of a given dose than at corresponding points in time after i.m. injection after the same dose. Thus absorption of oral CDX is reasonably rapid and complete, whereas the absorption rate of i. m. CDX is slow.
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 15 (1979), S. 269-274 
    ISSN: 1432-1041
    Schlagwort(e): phenytoin ; food-intake ; bioavailability ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The influence of food intake on the absorption of phenytoin was examined in eight healthy volunteers, by study of single-dose kinetics following ingestion of phenytoin 300 mg either with a standardized breakfast or on an empty stomach. Blood samples were collected at regular intervals from 0 to 48 h, and serum concentrations of unmetabolized phenytoin were determined by gas chromatography. Serum concentrations of the major metabolite of phenytoin, 4-hydroxyphenytoin, were measured by mass fragmentography. Concurrent intake of food and phenytoin appeared to accelerate absorption of the drug from the formulation used, and the peak concentrations were significantly higher (mean increase 40%) in the postprandial than in the preprandial state. As reflected by the AUC (area under the curve), the amount of drug absorbed was increased during postprandial conditions, although the difference only reached borderline significance. It is suggested that phenytoin should always be taken in a defined relation to meals.
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  • 30
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 16 (1979), S. 107-112 
    ISSN: 1432-1041
    Schlagwort(e): quinidine ; enteric-coated tablets ; bioavailability ; gastric emptying ; pH
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The absorption of quinidine from single and multiple doses of an enteric-coated preparation (Systodin®) was studied in seven healthy subjects, and was compared with the pharmacokinetics of intravenously administered quinidine and the results of in vitro dissolution tests of the tablets. Absorption of quinidine began after a variable delay, 2–8 h (mean 4.8) after fasting and 3–10 h (mean 6.1) after food. The rate of absorption varied both in and between individuals. It appeared to be lower when the drug was administered after food. Multiple doses after food gave a pattern of plasma concentration-time curves similar to that found on administration of single doses after food. The delay prior to absorption was prolonged at night. The ratio between the maximum and minimum concentration of quinidine during a dose interval varied from 1.3 to 3.2 (mean 2.0). Bioavailability of quinidine in fasting subjects ranged from 69 to 95% (mean 83); variation was greater when doses were administered after food. The release of quinidine from the enteric-coated preparation was pH dependent and was sustained at low pHs as may be found in the intestines. The results indicate that the absorption of quinidine from the enteric-coated formulation was dependent on the highly variable rate of gastric emptying and the pH of intestinal fluid, and it varied greatly both within and between individuals.
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  • 31
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 16 (1979), S. 141-147 
    ISSN: 1432-1041
    Schlagwort(e): prazepam ; N-desmethyldiazepam ; bioavailability ; pharmokinetics ; electron-capture gasliquid chromatography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary An original electron-capture gas chromatographic assay was developed for simultaneous measurement of plasma levels of the benzodiazepine derivative prazepam and of its principal unconjugated metabolite, N-desmethyldiazepam. The assay was used to study the pharmacokinetics of the drug and its comparative bioavailability from tablets and from a specially prepared solution. Nine healthy adult volunteers were studied. Each volunteer on one occasion took 30 mg of the drug in tablet form, and on another occasion 30 mg of the drug in solution. In all subjects, N-desmethyldiazepam appeared in plasma shortly after prazepam appeared and reached a peak within four hours of prazepam ingestion. Thereafter plasma N-desmethyldiazepam levels were much higher than plasma prazepam levels throughout. Prazepam became undetectable within six hours of intake, whereas its metabolite could still be measured in plasma fourteen days after dosage. Thus much of the pharmacological action of prazepam may be mediated through its metabolite, N-desmethyldiazepam. In five of the nine subjects, areas under the plasma level curves for the metabolite were not markedly different for the tablet and solution formulations studied. In the other four subjects the area under the curve for the tablets was 50% to 80% of the area under the curve for the solution. The time to reach peak plasma level for the metabolite was shorter after the solution formulation (mean 2.0±SD 1.2 h) than after the tablet formulation (mean 4.2±SD 1.7 h).
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  • 32
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 10 (1976), S. 55-58 
    ISSN: 1432-1041
    Schlagwort(e): Penicillin V ; bioavailability ; pharmacokinetics ; dose ranging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary An absorption study was performed in ten healthy volunteers to test the bioavailability of various doses of two penicillin V-K preparations: Isocillin® (Hoechst AG, Federal Republic of Germany), — tablets of 600 000 and 1.2 Mega U; V-Cillin® (Eli Lilly, USA), — tablets of 200 000, 400 000 and 800 000 U. The serum concentrations and elimination of the active substance in urine were measured for six hours after administration. Independently of the source of the preparation, a strict linear relation between the dose and the area under the serum curve (AUC), or between the dose and the urinary elimination, was demonstrated by regression analysis. The dose-dependent increase in the AUC was highly significant (p〈0.01) in the range tested, i.e. between 200 000 and 1.2 Mega U. The relative elimination of active substance in urine lay within narrow limits for all doses (35.7–41.3%). Thus, both compounds proved to have the same bioavailability.
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  • 33
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 10 (1976), S. 237-243 
    ISSN: 1432-1041
    Schlagwort(e): Ampicillin ; bioavailability ; pharmacokinetics ; branded products ; proprietary preparations ; capsule formulation ; tablet formulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetics and bioavailability of three different brands of ampicillin were studied in 10 volunteers. After intravenous administration ampicillin can be described adequately by a two-compartment open pharmacokinetic model. The half-life during the α-phase was 9 min and the β-half-life was in the range 50–60 min, independent of the mode of administration. Absolute bioavailability was determined from the ratio of the areas under the serum concentration curves obtained after oral and intravenous administration of equal doses. Bioavailability was also estimated by analysis of variance. The results indicated absolute availability of the three products of 39–54%. One of the products, a capsule formulation, showed a significantly lower bioavailability than the others, which were tablet formulations.
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  • 34
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 11 (1977), S. 277-281 
    ISSN: 1432-1041
    Schlagwort(e): Proscillaridin ; oral administration ; portal venous sample ; porto-peripheral concentration difference ; bioavailability ; 86Rb-uptake inhibition assay
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The absorption of proscillaridin A was studied in four patients undergoing catheterization of the portal vein for diagnostic purposes. Proscillaridin 1.5 mg was given as a single oral dose and plasma glycoside activity was analyzed by the86Rb-uptake inhibition technique. Proscillaridin appeared rapidly in the portal blood, peak activity being found after 15 min in three and after 30 min in one patient. In peripheral blood the peak activity occurred after approximately 35 min. Despite rapid passage across the gut wall, porto-peripheral differences in glycoside activity were small; they were zero after 4 h. The mean amount absorbed as active proscillaridin during the first 4 h after the dose was calculated to be only 7.1% of the given amount. Late porto-peripheral differences, probably due to enterohepatic recycling, appeared after 6 h in three patients. The results suggest that proscillaridin undergoes first pass inactivation in the gut wall. Enterohepatic recirculation may contribute to the amounts of active glycoside that reach the systemic circulation.
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  • 35
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 10 (1976), S. 49-54 
    ISSN: 1432-1041
    Schlagwort(e): Three-compartment open model ; intravenous infusion ; apparent volume of distribution ; renal insufficiency ; miconazole ; bioavailability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetic profile of miconazole has been studied in normal subjects and in patients suffering from severe renal insufficiency; one group of patients was undergoing intermittent haemodialysis. A three-compartment open model was fitted to the observed plasma concentrations obtained after intravenous infusion of miconazole 522 mg over fifteen minutes. The rate constants of elimination and exchange between compartments computed for the three groups were not significantly different. The apparent volumes of distribution in the cases of renal failure not undergoing haemodialysis were significantly smaller than the corresponding control values. A computational procedure is described which reduces observations obtained after infusion to the case of a single rapid intravenous administration.
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  • 36
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 11 (1977), S. 207-212 
    ISSN: 1432-1041
    Schlagwort(e): Chlorpropamide ; hypoglycaemic agent ; bioavailability ; plasma concentrations ; bioequivalence ; dissolution tests
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The bioavailability of chlorpropamide from two new formulations (Melitase® tablets) has been compared to that from a reference formulation which is currently in clinical use as a hypoglycaemic agent. In both rate and extent of bioavailability, all three formulations may be considered equivalent, providing allowances are made for differences in drug content. With 95% confidence, the mean bioavailability of chlorpropamide from the new formulations was within about 16% of the mean from the reference formulation, and formulation-related differences were not statistically significant. Although all three formulations were shown to have similar dissolution profiles, dissolution of chlorpropamide was pH-dependent in vitro. Dissolution was almost complete during 30 min at pH 7.2, but only 40%–60% had dissolved during 90 min at pH 2.0. A peak mean concentration of 22.7 µg/ml was reached 3 h after administration of 2×100 mg tablets of the new formulation and peak mean concentrations of 26.8 µg/ml and 27.4 µg/ml were reached 3 h and 4 hours after administration of one 250 mg tablet of the new formulation and one 250 mg tablet of the reference formulation respectively. Formulation-related differences of mean plasma concentrations (after scaling for equal doses of 250 mg) were not significant and each formulation provided similar plasma concentrations at corresponding times after administration. Statistically significant subject-related differences in all the parameters of bioavailability were shown by analyses of variance.
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  • 37
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 16 (1979), S. 355-360 
    ISSN: 1432-1041
    Schlagwort(e): ergotamine ; migraine ; bioavailability ; radioimmunoassay ; plasma level ; CSF level ; continuous dosing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Plasma ergotamine concentrations were determined by radioimmunoassay in 10 healthy subjects after a 2 mg oral dose of ergotamine, administered at 24 h intervals on three consecutive days. After the first dose the mean peak plasma level of 0.35±0.05 (SEM) ng/ml was found 1–2 h after administration. In the samples obtained 2 h after the second and third doses, plasma ergotamine levels did not exceed the first peak value. On the other hand, after the third and last dose the plasma ergotamine began to rise slowly, reaching maximum of 0.70± 0.10 ng/ml on the 6th day after administration. This supports the concept of accumulation of the drug or of immunoreactive metabolites. CSF ergotamine was determined in 4 patients, who underwent lumbar puncture for other diagnostic purposes, 1 to 2 h after the 2 mg oral dose. A concentration of 0.40± 0.03 ng/ml was observed. In seven out of 18 migraine patients who were taking ergotamine preparations daily (mean 11.7 mg/week), ergotamine could not be detected in plasma 1 h after administration of the dose. In the remaining migraine patients, the pattern of plasma ergotamine after both the daily and the test doses was similar to that of the 10 healthy subjects. The results in volunteers and migraine patients suggest notable variation in bioavailability of the drug. It seems that in most subjects there is accumulation or tissue redistribution of ergotamine or its immunoreactive metabolites, although in a significant number of migraine patients who use the drug daily, ergotamine does not appear to be biologically available.
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  • 38
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 16 (1979), S. 405-410 
    ISSN: 1432-1041
    Schlagwort(e): diclofenac ; plasma levels ; intravenous bolus administration ; oral administration ; enteric coating ; bioavailability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetics of diclofenac were examined following single rapid intravenous injection and also following single oral doses to healthy female volunteers. After intravenous injection plasma levels of diclofenac fell rapidly and were below the limits of detection at 5.5 h postdosing. Individual drug profiles were described by a triexponential function and mean half-lives of the three exponential phases were 0.05, 0.26 and 1.1 h. After oral doses of enteric-coated tablets, the lag time between dosing and the appearance of drug in plasma varied between 1.0 and 4.5 h. However once drug absorption had commenced similar plasma drug profiles were obtained in different individuals. Peak plasma diclofenac levels ranged from 1.4 to 3.0 µg · ml−1. The mean terminal drug half-life in plasma was 1.8 h after oral doses. This value was not significantly greater than the value of 1.1 h following intravenous doses. Fifty percent of orally dosed diclofenac did not reach the systemic circulation due, predominantly, to first-pass metabolism.
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  • 39
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 11 (1977), S. 219-224 
    ISSN: 1432-1041
    Schlagwort(e): Nortriptyline ; 10-OH-nortriptyline ; bioavailability ; plasma metabolites ; first pass metabolism ; oral dose ; intramuscular dose
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Nortriptyline was given orally and intramuscularly to six depressed patients. Plasma concentrations of parent drug and the unconjugated and conjugated principal metabolite, 10-hydroxynortriptyline, were determined by mass fragmentography. There was a significant decrease in the area under the nortriptyline plasma concentration — time curve after the oral route of administration, whilst the elimination rate was unchanged. With the oral dose, plasma concentrations of the metabolites were higher and peaked earlier than after intramuscular administration, whilst the opposite was true for the parent compound. This proves that the difference in bioavailability between the two routes of administration was due to first pass metabolism. As determined from the ratio between corresponding areas, the relative bioavailability of the oral dose was 66±21 S.D. per cent. This fraction is higher than that reported previously when intravenous nortriptyline was used as the reference dosage form.
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  • 40
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 12 (1977), S. 281-284 
    ISSN: 1432-1041
    Schlagwort(e): Tetracycline ; bioavailability ; plasma levels ; nutritional state ; man
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Relative bioavailability after oral administration of a single dose and Cmin levels of tetracycline in plasma after multiple doses were determined in groups of well-nourished and undernourished subjects. The relative bioavailability of tetracycline, assessed by the area under serum concentration time-curves, did not differ in undernourished and well-nourished patients. The plasma levels were not different in the two groups after the conventional dose of tetracycline HCl 250 mg at 6 hour intervals. However, in these studies undernourished subjects received a higher dose per kg body weight, which could have compensated for any effect of a shortened half life of the drug. When the dose per kg body weight was reduced, the Cmin levels were lower. On the other hand, with the same dose per kg body weight at more frequent intervals, the plasma concentrations were similar to those in well-nourished subjects. These studies indicate that the dosage regimen should be based both on body weight and on the nutritional status of the individual.
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  • 41
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 12 (1977), S. 65-68 
    ISSN: 1432-1041
    Schlagwort(e): Indomethacin ; antacids ; drug-drug interactions ; bioavailability ; drug combinations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The biovailability of indomethacin from two indomethacin-antacid (aluminum hydroxide magnesium carbonate and magnesium hydroxide) combinations was compared with the bioavailability of oral indomethacin. Relative bioavailability was estimated by three methods: comparison of plasma concentrations at various times, comparison of areas under plasma concentration time curves, and comparison of the amount of drug excreted unchanged in the urine. A double blind three-way crossover study was conducted in twelve healthy volunteers. The combination with the slightly smaller amount of antacid (preparation A) showed significantly decreased bioavailability by all three methods in comparison with indomethacin alone (preparation C). The combination with the larger amount of antacid (preparation B) was also less bioavailable than preparation C. This effect was significant only for the comparison of areas under curves and not for plasma levels, although the mean plasma levels produced by preparation B at all times were lower than those for preparation C. These findings suggest that aluminum hydroxide magnesium carbonate and magnesium hydroxide decrease the bioavailability of indomethacin.
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  • 42
    ISSN: 1432-1041
    Schlagwort(e): Tolmetin ; pharmacokinetics ; bioavailability ; antacid ; oral dose
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The purpose of this study was to determine whether a concomitant single dose of antacid or multiple doses of antacid administered prior to, and with tolmetin, alter the pharmacokinetics of tolmetin when the drug was administered as a commercially available tablet containing tolmetin sodium. The possible effects of the antacid on plasma concentrations and urinary excretion of tolmetin and its major metabolite were evaluated following administration of: (a) tolmetin sodium alone; (b) antacid four time a day for three days prior to a single dose of tolmetin sodium, with continuation of the antacid during the day tolmetin was given; and (c) co-administration of single doses of tolmetin sodium and antacid. The twenty-four subject study was of the crossover type. There were no significant differences among treatment means for: (i) peak plasma concentrations of both tolmetin and metabolite, (ii) AUC 0–8 h and AUC 0-∞ for both tolmetin and metabolite, (iii) time to peak plasma concentration for both tolmetin and metabolite, (iv) plasma concentrations of both tolmetin and the metabolite at all sampling times (except for tolmetin at 2 h), (v) renal clearance of both tolmetin and its metabolite, and (vi) the amount of metabolite excreted in the 0–24 h urine. There were small, but significant, differences among amounts of tolmetin excreted in the 0–24 h urine. Semilogarithmic plots of both tolmetin and metabolite plasma concentrations past the peak concentrations were curved over the entire 8-h observation period; although the elimination half-life of tolmetin has been reported to be about one hour, the half-life most probably exceeds 2.6 h in most subjects. The results of this study indicate a lack of a significant drug-drug interaction between the non-steroidal anti-inflammatory agent, tolmetin sodium, and a commonly used antacid, which is a mixture of magnesium and aluminium hydroxides.
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  • 43
    ISSN: 1432-1041
    Schlagwort(e): Coumarin ; 7-Hydroxycoumarin ; drug disposition ; first-pass effect ; bioavailability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetics of coumarin (C) upon i.v. and p.o. administration and its metabolites 7-hydroxy-coumarin (7-HC) and 7-hydroxy-coumarin glucuronide (7-HCG) have been studied. Six healthy volunteers were involved in this investigation. Four of the volunteers participated in a crossover study. Coumarin was administered i.v. and p.o. in dose sizes of 0.25 mg/kg and 0.857 mg/kg, respectively. Coumarin is rapidly absorbed p.o., however the availability to systemic circulation is less than 4%. The rest of the dose appears quantitatively as 7-HC and 7-HCG in systemic circulation suggesting an extensive firstpass effect. Coumarin and 7-HCG are best fitted to an open two-compartment model, whereas 7-HC is best fitted to an open one-compartment model. The biological half-life of both C (0.80 vs. 1.02 h) and 7-HCG (1.47 vs. 1.15 h) was not significantly different for the two routes of administration. The large total clearance of C again suggests a first-pass effect; while that of 7-HCG, which is nearly exclusively eliminated into urine, indicates active tubular secretion of the glucuronide.
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  • 44
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 13 (1978), S. 35-39 
    ISSN: 1432-1041
    Schlagwort(e): Norethindrone ; bioavailability ; man ; competitive protein binding ; sex differences ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary A competitive protein binding assay for norethindrone was developed to measure plasma levels in human subjects. The plasma levels were considerably higher in women than in men, especially at low dose levels. The plasma levels were directly related to the dose in men; but greater variations in the plasma levels were observed in women. The plasma half-life was about 5 h in both sexes with single oral doses of 5 to 20 mg. A comparative bioavailability study with norethindrone from 2 different manufacturers, formulated in the same manner, showed no significant differences in absorption characteristics and provided sufficient data for pharmacokinetic analysis.
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  • 45
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 14 (1978), S. 261-265 
    ISSN: 1432-1041
    Schlagwort(e): Procainamide ; slow release formulations ; bioavailability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Procainamide was given to 20 patients with normal renal function as an i.v. bolus of 500 mg followed by 1.0 or 1.5 g eight-hourly by mouth in the form of a slow release preparation (Durules). 97.6±27.1 (SD)% of the oral procainamide was absorbed, the absorption half life being 1.54 h. The elimination half life following the oral formulation was 6.0±0.8 h, compared to a mean of 3.4±0.4 h following i.v. administration. Elimination half life following i.v. administration was slightly related to acetylator status, being 2.75±0.9 h in fast acetylators, and 4.4±2.4 h in slow acetylators. This dependence on acetylator status was not seen in half life following oral administration. Total body clearance, steady state plasma procainamide and N-acetylprocainamide were not significantly dependent on acetylator status, although a few patients who are slow acetylators had unexpectedly low clearance and high steady state procainamide concentrations when given the higher dose.
    Materialart: Digitale Medien
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  • 46
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 14 (1978), S. 357-360 
    ISSN: 1432-1041
    Schlagwort(e): Lanoxin tablets ; Lanoxicaps ; sorbitol ; bioavailability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary (1) The mean cumulative urinary digoxin excretion over 8 days was compared in 8 healthy volunteers after single doses of digoxin administered as 3 Lanoxin tablets of 0.25 mg, 3 digoxin tablets of 0.2 mg, 12 Lanoxicaps without sorbitol of 0.05 mg, 6 Lanoxicaps without sorbitol of 0.1 mg digoxin, 3 Lanoxicaps without sorbitol of 0.2 mg and 3 Lanoxicaps with sorbitol of 0.2 mg. (2) There was no significant difference between the 8 day cumulative urinary excretion for any of the Lanoxicaps treatments. (3) Cumulative urinary excretion after 3 digoxin tablets of 0.2 mg was significantly (P〈0.05) lower than after all other treatments. (4) Cumulative urinary excretion after 3 Lanoxin tablets of 0.25 mg was not significantly different from that after any of the Lanoxicaps treatments except 0.1 mg Lanoxicaps without sorbitol, it was significantly (P〈0.05) lower after the latter. (5) Mean urinary excretion of digoxin was 60% of ingested dose for all Lanoxicaps treatments and was significantly (P〈0.05) higher than the mean value of 50% for both tablet treatments. (6) Enhanced absorption of digoxin from Lanoxicaps was confirmed and shown to be unrelated to the sorbitol content of the capsule shell.
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  • 47
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 10 (1976), S. 347-359 
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; nickel-chromium alloys ; Group III–V elements ; reactive minor additions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The corrosion of a number of experimental ternary Ni-15 wt. % Cr-0.5wt. %X alloys (where X= Y, La, Ce, Sm, Th, U, Zr, or V) has been assessed in pure oxygen at 900° C for periods of exposure up to 450 hr, and compared with the behavior of an Ni-15% Cr control alloy. It has been established that while all of the alloys oxidize in accordance with a protective, approximately parabolic regime, considerable differences in oxidation rates are exhibited. In particular, additions of La, Ce, and Th bring about progressively enhanced rates of oxidation relative to the binary alloy, whereas Y, Sm, V, U, and Zr effect increasingly reduced rates of oxidation in the order given. The rate constant for the Th-bearing alloy is about two orders of magnitude larger than that for the alloy containing Zr. Such differences in behavior seem to be associated with subtle variations in the morphology/composition of the corrosion products from alloy to alloy. The observations are considered in the light of earlier published literature concerning the effects of rare-earth and other reactive elements on the oxidation behavior of Ni/Cr alloys.
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  • 48
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 10 (1976), S. 189-223 
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; platinum ; platinum-aluminum alloys ; alumina (Al2O3) ; oxide-scale adhesion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The development, growth, and adhesion of α-Al2O3 scales on platinum-aluminum alloys containing between 0.5 and 6 wt.% aluminum have been studied at temperatures in the interval between 1000 and 1450° C. The morphologies and microstructures of the α-Al2O3 scales were found to be influenced by the temperature, oxygen pressure, and the microstructures of the alloys. The oxidation rates of the alloys appeared to be controlled by transport of oxygen along grain boundaries in the α-Al2O3 scales. The α-Al2O3 scales adhered to the platinum-aluminum substrates even after extensive periods of cyclic oxidation. The good adhesion of the α-Al2O3 may result from mechanical keying of the oxide to the alloys due to the development of irregular oxide-alloy interfaces.
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  • 49
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 10 (1976), S. 277-289 
    ISSN: 1573-4889
    Schlagwort(e): alloy ; iron ; aluminum ; silicon ; oxidation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Silicon or chromium can be used as an oxygen getter in iron-aluminum alloys to prevent the internal oxidation of aluminum. This suppresses the formation of the iron oxide nodules that tend to destroy binary iron-aluminum alloys during high-temperature oxidation. Alloys of iron containing aluminum and silicon in varying proportions were heated in flowing air for 50 hr at 1093°C. Of the alloys tested, one containing 6% aluminum and 1 % silicon was the most resistant to oxidation.
    Materialart: Digitale Medien
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  • 50
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 10 (1976), S. 311-327 
    ISSN: 1573-4889
    Schlagwort(e): defect structure ; CoO ; oxidation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The total concentration of point defects and deviation from stoichiometry in Co1-yO have been determined experimentally as functions of temperature and equilibrium oxygen pressure in the temperature range 1000–1250°C and oxygen pressure range 10−3-1 atm. This total concentration of defects has also been calculated from known values of the coefficients of chemical diffusion and tracer self-diffusion of cobalt. The results of the two methods agree well. It has been found in the investigated range of temperature and oxygen pressure that the defect structure of cobaltous oxide is composed not only of defects due to deviation from stoichiometry, singly ionized cation vacancies, and an equivalent amount of electron holes, but also of intrinsic defects, probably of the Frenkel type.
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  • 51
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 10 (1976), S. 341-345 
    ISSN: 1573-4889
    Schlagwort(e): α-Al2O3 ; platinum ; oxidation ; adhesion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The influence of externally located platinum on the isothermal stability of α-Al2O3 scales formed at high temperatures has been examined. It has been observed that a nickel-base alloy forms an external scale of α-Al2O3 during oxidation at 1200°C, but this scale breaks down isothermally, enabling a faster-growing Cr2O3-rich scale to develop. However, in the presence of platinum metal alongside the specimen in the furnace hot zone, the breakdown of the α-Al2O3 scale is postponed for a substantial period of time. It appears that platinum, as the volatile species PtO2, is incorporated into the growing α-Al2O3 scale where it either influences the stress relief mechanism at temperature or reduces oxidation growth stress generation and thus significantly enhances the isothermal stability of the scale.
    Materialart: Digitale Medien
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  • 52
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 10 (1976), S. 377-401 
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; iron ; Mössbauer ; electron re-emission ; ERM spectroscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The results of an electron re-emission Mössbauer (ERM) spectroscopy study of the oxidation of metallic Fe at temperatures from 150 to 500°C in pure oxygen ( $${\text{p}}_{{\text{O}}_{\text{2}} } \approx {\text{ }}10$$ Torr) are presented. The oxidized samples were prepared from a metallic Fe sample enriched to 70% in the Mössbauer isotope Fe57 and the oxidation kinetics were determined volumetrically. Scanning electron microscopy was employed to characterize the morphology of the oxide films. The hematite, magnetite, and total-oxide thicknesses were determined from the ERM spectra using a theory recently developed in this laboratory, and the results were found to agree well with the measured oxygen content of the oxide films. For Fe and Fe-base alloys it is shown that the ERM technique is most useful in the oxide-thickness range of approximately 20–3000 Å within that range, oxide-phase identifications and thickness determinations are perhaps more readily determined by ERM spectroscopy than by any competing technique. In particular, the ERM measurement is nondestructive, and no supplementary measurements (such as surface-roughness determinations) or special sample preparations (such as oxide-film stripping) are required
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  • 53
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 11 (1977), S. 57-62 
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; scale growth
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Equations are presented to modify the classical theoretical expressions for the parabolic rate constant for the case in which the scale has a large composition range and a large variation in molar volume. The modifications appear as simple averages, together with a factor f.Evaluation of f for some hypothetical cases shows that it is near unity unless the composition gradient has an extreme deviation from linearity.
    Materialart: Digitale Medien
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  • 54
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 11 (1977), S. 193-198 
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; scaling ; wustite ; magnetite ; iron
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The theory of the growth of two oxide layers by Yurek et al. has been applied to the oxidation of iron at 1100° C. The theoretical parabolic rate constants for the simultaneous growth of the two oxide layers were calculated from radioactive tracer diffusion coefficients for wustite and magnetite. Good agreement was found between the theoretical and experimental values of the ratio of scale thicknesses.
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  • 55
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 12 (1978), S. 227-245 
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; sulfidation ; iron-chromium-nickel alloy ; thermochemical diagram ; parabolic rate constant
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Oxidation-sulfidation studies of Fe-Cr-8Ni alloys with 4, 12, and 22 wt. % Cr were conducted at 750 and 875°C in multicomponent gas mixtures that contained CO, CO2, CH4, H2, and H2S. The reaction processes resulted in parabolic kinetics. A chromium concentration in the range 0–12 wt. % in the alloy had a negligible effect on the parabolic rate constant; however, the rate constant for the alloy with 22 wt. % Cr was significantly lower. For a given sulfur partial pressure, the oxygen partial pressures required for the formation of a continuous oxide layer in an Fe-22Cr-8Ni alloy were ∼102 to 103 times those calculated for Cr-Cr2O3 equilibrium at temperatures of 875 and 750° C, respectively.
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  • 56
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 12 (1978), S. 451-471 
    ISSN: 1573-4889
    Schlagwort(e): HCl gas ; H2O vapor ; Ni-Cr-Al alloy ; oxidation ; hot corrosion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Moist air containing HCl gas caused the oxide formed on a Ni-Cr-Al alloy at 850°C to crack during the early stages of growth, and extensive blistering and spalling occurred on cooling. In dry air containing HCl gas no oxide cracking was observed at temperature although the oxide blistered and spalled on cooling. In dry or moist air free from HCl an adherent protective oxide formed which did not spall on cooling. The oxide cracking at temperature has been attributed to the production of hydrogen by reaction of Cr and Al in the alloy with water vapor and the removal of NiO as NiCl2 by reaction with HCl gas. Hydrogen produced by reaction of water vapor or HCl with Cr or Al dissolved in the alloy at temperature, but on cooling the hydrogen was released, causing the oxide to blister and spall. Preoxidation of the alloy in HCl-free atmospheres eliminated these effects of HCl gas in short-term isothermal tests.
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  • 57
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 9 (1975), S. 45-67 
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; hot corrosion ; nickel alloys ; composites
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation and hot corrosion behavior of a tungsten-fiber, reinforced Ni~ 20Cr alloy has been examined under the following exposure conditions: (a) pure oxygen at 1 atm pressure; (b) sulfidation in H2–10 %H2S; (c) presulfidation in H2–10 %H2S followed by oxidation in oxygen; and (d) oxidation in 1 atm oxygen after precoating with approximately 1 mg/cm2 of Na2SO4. Rapid oxidation of the tungsten fibers causes considerable distortion of the matrix and catastrophic degradation of the matrix follows. Inter diffusion between the matrix and the fibers is also important. During sulfidation, only the matrix forms sulfides, the fibers remaining unaffected. Consequently, presulfidation, although having a dramatic effect on the oxidation of the matrix does not have a damaging effect on the fibres. Equally, the presence of sodium sulfate is not critical, although severe oxidation of the exposed tungsten fibers is still observed.
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  • 58
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 9 (1975), S. 275-305 
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; Ni-Cr alloys ; rare-earth oxide dispersion ; dispersion-strengthened alloys
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation behavior of Ni-20%Cr alloys containing approximately 3 vol.% Y2O3, ThO2, and A12O3 as dispersed particles has been examined in the temperature range 900 to 1200° C in slowly flowing oxygen at 100 Torr. The results show that the oxidation behavior of the Y2O3-, ThO2-, Al2O3-, and Ce02-containing alloys is very similar and that some anomalies in the behavior of the ThO2-containing alloy might be explained by the slower rate of chromium diffusion in this coarse-grained alloy. Two Al2O3-containing alloys were studied. One with a relatively coarse dispersoid size behaved in a manner analogous to a dispersion-free Ni-30% Cr alloy at 1100°C. The other alloy contained a dispersion of fine Al2O3 particles and behaved exactly like the Y2O3-containing alloy at 1000 and 1100°C, but at 1200° C oxidized at a faster rate. It has been shown that the adherent scales on dispersion-containing alloys have a stabilized fine grain size, whereas the nonadherent scales on dispersion-free alloys undergo grain growth.
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  • 59
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 9 (1975), S. 415-425 
    ISSN: 1573-4889
    Schlagwort(e): vanadium carbide ; vanadium oxycarbide ; oxidation ; parabolic rate law ; cubic rate law ; chemisorption
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation of an oxycarbide of vanadium, VO0.6C0.7, and of a vanadium carbide, VC0.98, was studied athermally up to temperatures of 800° C and isothermally between 400 and 580° C at oxygen pressures ranging from 10−2 to 1 atm. The oxycarbide followed the parabolic rate law below 450° C with V2O5 forming as the only reaction product. The activation energy was 49 kcal/mole. VC0.98 did not form an oxide in this temperature range, but rather dissolved oxygen, the activation energy being 26.6 kcal/mole. No oxygen pressure dependence on the kinetics was found for either sample in this temperature range. Both samples followed the cubic rate law during oxidation in the range of 500–580° C during which V2O5 formed. There was a P1/3 dependence and the activation energy was the same for both materials, 51 kcal/mole. The cubic rate law and the positive pressure dependency (rather than an anticipated negative dependency) were attributed to an electric field associated with oxygen ions chemisorbed on a thin layer of V2O5.
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  • 60
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 9 (1975), S. 459-472 
    ISSN: 1573-4889
    Schlagwort(e): Cr ; oxidation ; kinetics ; Cr2O3 grain size ; short-circuit diffusion ; surface ; preparation ; Fe-Cr
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Cr was oxidized in 1 aim O2 at 980, 1090, and 1200°C. ElectropolishedCr and some orientations of etched Cr oxidize rapidly and develop compressive stress in the growing Cr2O3; other orientations oxidize slowly, apparently free of stress. SEM examination of fracture sections shows that the thick oxide is polycrystalline whereas the thin oxide on etched Cr is monocrystalline. It is deduced that the monocrystalline oxide grows by lattice diffusion of cations outward, and the polycrystalline layer by the two-way transport of cation diffusion outward and anion diffusion inward along oxide grain boundaries. The consequent formation of oxide within the body of the polycrystalline layer generates compressive stress and leads to wrinkling by plastic deformation. The activation energy for oxidation of Cr by cation lattice transport is 58 kcal/mole. Polycrystalline Cr2O3 forms on Fe-26Cr alloy, whether electropolished or etched; oxidation is accordingly rapid and accompanied by compressive stress.
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  • 61
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 10 (1976), S. 85-95 
    ISSN: 1573-4889
    Schlagwort(e): boron carbide ; oxidation ; kinetics ; chromatography method
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Thermogravimetry and gas-adsorption chromatography were used to study the kinetics of formation of solid and gaseous products during the hightemperature oxidation of compact boron carbide in oxygen at 740 Torr. Oxidation resistance was observed at temperatures up to 1200°C. The main oxidation products were B2O3 and CO2. Oxidation was paralinear; the carbon consumption exceeded the consumption of boron as compared to the ratio of these elements in the compound B4C. This difference resulted in carbon depletion of the carbide layer in the substrate near the scale〉.
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  • 62
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 10 (1976), S. 255-276 
    ISSN: 1573-4889
    Schlagwort(e): Zircaloy-4 ; zirconium ; alloy ; oxidation ; microstructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The ZrO 2 scales formed on Zircaloy-4 PWR tubes during corrosion in steam in the temperature range of 1000–1300°C have been found to contain a metallic phase that is relatively rich in Sn. The precise composition of the metallic phase has not been determined. Most of the metallic phase is located in a line of metallic particles, which is oriented parallel to the alloy-scale interface and located near the center of the scale. The exact morphology of the scale on either side of the particle line has not been identified. The oxide between the metallic particles and the scale-steam interface contains very little Sn, except for a narrow zone adjacent to the scale-steam interface, which was formed in the beginning of the reaction. It appears that the scale between the metallic particles and the alloy-scale interface consists of thin columnar grains of ZrO 2 with a very fine metallic phase probably located at the ZrO 2 grain boundaries. The experimental evidence presently available indicates that the metallic phase exists in the scales at the reaction temperature. If the metallic particles were rich enough in Sn, then a liquid metallic phase would exist in the oxide during the reaction. Kinetic studies demonstrate that these particles move with respect to the scale-steam interface toward the center of the alloy during the course of the oxidation reaction. It appears that the presence of the line of metallic particles could, under certain conditions, markedly influence the mechanical properties of the oxide scales formed on Zircaloy-4.
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  • 63
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 11 (1977), S. 23-56 
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; carburization ; carbonaceous gases ; superalloys ; stainless steels ; film formation ; structure of oxide scales ; preoxidation ; metal dusting
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Formation and deterioration of oxide films on several contemporary high-temperature alloys was studied in various carbonaceous gas atmospheres. Scanning electron microscopy and metallographic examination were applied to films on Fe-Cr-Ni and Ni-Cr-Al type alloy compositions exposed in CH 4/H2 and CO/CO2 atmospheres at temperatures up to 900° C and pressures up to 900 psi (6.2 × 106 N/m2). The effects of various preoxidation treatments were evaluated. Reduction of certain oxide phases is observed to promote catalytic gas decomposition. Al2O3 components in the films are observed to be stable under the reducing conditions experienced. Carbon uptake by various alloys is found to be quite sensitive to surface finish, with an observed increase in penetration with surface roughness.
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  • 64
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 11 (1977), S. 225-239 
    ISSN: 1573-4889
    Schlagwort(e): tantalum ; oxidation ; high temperature ; kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation of tantalum in oxygen-nitrogen and oxygen-inert gas mixtures at925°C has been studied. The oxygen pressure was close to 0.5 atm in all experiments, and partial pressures of the second component of from 0 to 180 Torr were employed. Spherical specimens were used to provide quantitatively significant kinetic data. A model has been proposed which suggests that the oxygen pressure at the reaction interface close to the metal surface is lower than the external pressure because of the finite permeability of the porous outer oxide layer, and that the inert gas effectively reduces the permeability. The model gives good quantitative agreement with the experimental results.
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  • 65
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 12 (1978), S. 1-22 
    ISSN: 1573-4889
    Schlagwort(e): NaCl vapor ; Ni-Cr-Al alloy ; oxidation ; hot-salt corrosion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract A thin protective oxide formed on a Ni-19.7 Cr-2.4 Al alloy in air at 850°C. Microstructural examination of stripped films showed that the oxide was duplex with an inner chromium-rich layer of NiCr2O4 + Cr2O3 with probably some NiAl2O4 + Al2O3, and an outer nickel-rich layer, principally NiO. The oxide grew faster in the presence of NaCl and it differed significantly in microstructure and composition from a very early stage. The thicker regions of the oxide assumed regular polyhedral shapes in air + NaCl, rather than the irregular nodular shape exhibited in clean air, as well as becoming richer in chromium. The results suggest that chloride vapor increases cationic mobility in the oxide. It is proposed that Cl− ions are incorporated in the oxygen close-packed lattice, thereby increasing ionic mobility in Cr2O3.
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  • 66
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 12 (1978), S. 83-110 
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; iron ; chromium ; Fe-9% Cr alloy ; Auger electron spectroscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation or general corrosion behavior of metals at pressures of 1 atm or more is usually investigated by oxidizing samples under prescribed conditions and then subsequently characterizing the surface produced using one or more of the experimental methods available. This article describes a method which obviates the necessity of transferring samples from the oxidizing environment to the instrument for analysis, is nondestructive, and monitors the oxidizing surface in situ. The oxidation of iron, chromium, and a 9% chromium-iron alloy in carbon dioxide at atmospheric pressure and at 773°K is described. The surfaces of these materials were analyzed by Auger electron spectroscopy during exposure to the gas. Spectra and diagrams illustrating the variation in surface composition as oxidation proceeded are shown and possible mechanisms for the oxidation reactions are briefly discussed. The formation of the surface oxide on iron and on the 9% Cr-Fe alloy appears to follow very similar paths under the conditions of oxidation used. In all the materials studied trace impurities such as sulfur participated in the oxidation reactions.
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  • 67
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 13 (1979), S. 181-195 
    ISSN: 1573-4889
    Schlagwort(e): copper-manganese alloys ; oxidation ; scale composition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation behavior of copper-manganese alloys (2–35 wt. % Mn) in pure oxygen at 760 Torr was investigated at 100° intervals between 550 and 850°C. Gravimetric measurements of the oxidation kinetics have been combined with microstructural studies of the reacted samples in order to evaluate the reaction mechanisms. The scales formed on Cu-2Mn, Cu-5Mn, Cu-10Mn are always composed of three different layers; in any case manganese is present only in the inner layer. The scales formed on Cu-20Mn and Cu-35Mn are composed of two layers, both containing manganese, with a more Cu-rich outer layer. In all the samples internal oxidation in combination with external scale formation is observed.
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  • 68
    ISSN: 1573-4889
    Schlagwort(e): Cu-Si alloys ; oxidation ; kinetics ; silica
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation of Cu-Si alloys (containing up to 4.75 wt. % Si) in $${\text{p}}_{O_2 } $$ =0.01 atm from 800 to 1000°C has been investigated using thermogravimetry and other techniques. A 0.04% Si alloy followed a parabolic oxidation law with a rate similar to that of pure Cu. As the Si concentration increased the rate decreased and became irregular owing to SiO2 particles or flakes at the alloy-scale interface. It is considered that sintering of SiO2 particles and rupture of the sinter because of contraction during sintering are responsible for the irregular kinetics. A SiO2 layer forms directly on the 4.75% Si alloy which oxidizes uniformly. The SiO2 was always amorphous. In pure CO2 a similar pattern of amorphous SiO2 particles, flakes, and layers occurs.
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  • 69
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 13 (1979), S. 283-298 
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; surface alloys ; Fe-Cr alloys ; iron ; kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation behavior of several surface and bulk Fe-Cr alloys and iron at 300°C and 4×10−6 Torr oxygen was studied. The surface alloys were fabricated by implantation of 25 keV Cr ions into the outermost 300Å of polycrystalline iron samples. The oxide thickness as a function of oxygen exposure was obtained using proton-excited X-ray analysis, and composition profiles of oxide films were obtained using Auger electron spectroscopy and ion sputtering. The addition of Cr to Fe by surface and bulk alloying caused the oxidation rate to decrease and changed the oxidation kinetics from parabolic (for Fe) to logarithmic (for Cr concentrations ≥4.7at.%). Interpretation of the data in terms of simple oxidation theories indicates that the Cr additions may reduce the oxidation rate by altering the electronic properties of the metal-oxide interface.
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  • 70
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 13 (1979), S. 311-330 
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; oxide maps ; alloying additives ; Fe-Ni-Al alloys
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation behavior of iron-nickel-aluminum alloys containing 0–40 wt.% nickel and 0–30 wt.% aluminum has been investigated at 600 and 800° C. Through the construction of “oxide maps” it can be shown that three possible oxide morphologies may exist: Alloys containing less than approximately 5 wt.% aluminum form scales consisting of predominantly Fe2O3 and spinel; alloys with between 5 and 10 wt.% aluminum form Al2O3 scales interspersed by Fe2O3 nodules, and alloys with greater than 10 wt.% aluminum form predominantly γ-Al2O3 scales.
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  • 71
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 13 (1979), S. 223-236 
    ISSN: 1573-4889
    Schlagwort(e): nickel ; oxidation ; surface reactions ; X-ray photoelectron spectroscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract X-ray photoelectron spectroscopy has been used to study the oxidation of polycrystalline nickel metal. The results indicate that the oxidation process takes place in three stages; associative adsorption of molecular oxygen, followed by the combination of oxygen atoms with surface nickel atoms and, ultimately, the formation of bulk oxide. At room temperature only the first two stages can be detected. For exposures below 1 L the O 1s photoelectron spectrum is considered to be characteristic of an associatively adsorbed oxygen species, but for exposures above this value evidence for the formation of a monolayer of “NiO” is suggested by the development of an O 1s peak at 529.9 eV. Incorporation of oxygen into the nickel lattice is observed at temperatures 〉500°K. The activation energy for this place-exchange process was estimated at 1.80±0.06 eV.
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  • 72
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 13 (1979), S. 255-272 
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; Fe-C ; graphite deposition ; nonadherent oxide ; kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation of Fe-C alloys containing 0.5 and 1.0% C was studied in 1 atm O2 at 700° C. The oxidation rate is considerably slower than for pure Fe. The oxide scale formed is detached, multilayered, and overoxidized, containing little or no FeO. A thin film of graphite was identified at the metal-oxide interface by electron diffraction. It is proposed that the slow oxidation and abnormal scale are caused by a residue of graphite left at the metal surface from the oxidation of Fe3C. This inhibition of the oxidation of Fe by carbon at 700°C is in contrast to the stimulation observed at 500°C.
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  • 73
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 9 (1975), S. 69-97 
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; decarburization ; Fe-C alloys ; effect of humidity ; effect of microstructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Isothermal oxidation treatments were carried out on an Fe-C alloy (0.4 % C): (a) in almost dry air around A1, and also with an Fe-C alloy (0.5% C) and IRSID pure iron; (b) in dry air ( $${\text{P}}_{H_2 O} \simeq 10^{ - 5} $$ nm Hg); (c) in almost dry air(1–2% water vapor) at 700° C; and (d) in moist air (31% water vapor). Theresults are as follows: The rate of oxidation at a temperature below A1depends chiefly on alloy structure, i.e., on thermal history of the sample.The water vapor content of the air strongly influences the scale adherenceas well as the rate of oxidation of the Fe-C alloys below A1, but has virtuallyno effect on the rate of oxidation of pure iron. Under the same conditions, avery light decarburization of metal occurs in air, whereas no decarburizationoccurred in air with 13% water vapor.
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  • 74
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 9 (1975), S. 225-257 
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; eutectic alloys ; refractory metals
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation behavior of the directionally aligned eutectic alloy, TaC-Co50B, has been examined between 600 and 1155°C. Parabolic oxidation behavior, isotropic in nature, is found to 800°C. Above 800°C, the oxidation behavior is no longer either parabolic or isotropic. The interaction between the Co matrix alloy and the TaC fibers adjacent to the oxidizing interface is reported as a function of temperature in oxidation.
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  • 75
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 9 (1975), S. 215-223 
    ISSN: 1573-4889
    Schlagwort(e): cation diffusion ; oxidation ; metal partition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract An alternative mass balance at the alloy-scale interface is proposed for the Wagner theory of binary alloy oxidation. A simple relation between the bulk composition of the alloy and the scale composition at the alloy-scale interface, ξ′, is derived in terms of the transport properties of the scale and the limit of application of the relation defined. There is good agreement between calculated and measured values of ξ′.
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  • 76
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 9 (1975), S. 427-440 
    ISSN: 1573-4889
    Schlagwort(e): cobalt ; cobalt-aluminum alloys ; oxidation ; thermal cycling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Most Ni and Co-base alloys used for high-temperature service rely on the production of a compact, stable Cr2O3 scale for their oxidation resistance. However, as operating temperatures have risen above 900–950° C, the loss of Cr2O3 as the volatile CrO3 has led to an inadequate life span of these alloys, particularly in rapidly flowing, turbulent gas streams. As a result of this, it has been necessary to examine the possibility of using Al2O3 as the protective scale. Al2O3 has a lower growth rate than Cr2O3, it is nonvolatile, and, unlike Cr-containing systems, it is less likely to form compound oxides such as spinels. In this study, the amount of Al which must be present in the Co-Al system to form a continuous layer of Al2O3 in the temperature range 800–1000° C has been determined. The quantity was found to rise from about 7–10 wt. % at 800° C to 10–13 wt. % at 900° C and 13 wt. % at 1000° C. Notice has also been taken of the abilities of the alumina-forming alloys to re-form a protective oxide in the event of spalling, blistering, or any other disruptions of the scale, and some “cyclic-oxidation” checks have been conducted on the Co13Al alloy at 900 and 1000° C.
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  • 77
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 10 (1976), S. 97-103 
    ISSN: 1573-4889
    Schlagwort(e): silicon carbide ; oxidation ; molecular oxygen ; glow-discharge oxygen plasma ; kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation kinetics and structure of the oxide scales formed on high-density SiC were studied in molecular oxygen at 740 Torr and in a glow-discharge oxygen plasma at 0.1 Torr at temperatures of 1000, 1100, and 1200°C. The monatomic oxygen formed by the glow discharge markedly increased the reaction rate and the vaporization of some of the oxidation products. The marked differences in kinetics suggest that the rate-controlling step during oxidation in molecular oxygen is the dissociation of adsorbed diatomic oxygen to the monatomic species. Films formed in molecular oxygen were mostly amorphous SiO2 with small inclusions of SiC and graphite, whereas films formed in dissociated oxygen were primarily amorphous SiO2 containing SiO, S2O3, and the coesite form of SiO2.
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  • 78
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 11 (1977), S. 91-106 
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; cyclic ; spallation ; stress
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Several alloys (one iron base and five nickel base) were cyclically oxidized in a series of tests in which the higher temperature (1100 or 1200° C) of the cycle was fixed at a level to allow ample oxidation in reasonable time and the lower temperature was variable to allow cycle temperature differences (ΔT s ) of up to 1400°C. The alloys oxidized included those which formed simple oxides such as Al2O3 or Cr2O3, as well as those which formed complex scales. Cooling rates were relatively low to minimize thermal shock effects. Each cycle consisted of 1 hr at the higher temperature and 1/2 hr at the lower temperature. Samples were tested up to 370 cycles. The extent of attack was determined by specific weight change which was continuously monitored. For all nickel alloys, as ΔT increased the extent of spallation increased. This effect was attributed to thermal expansion mismatches between the oxide and the nickel substrate. The FeCrAl alloy was not sensitive to ΔTand resisted spalling at ΔT levels to 1400°C. FeCrAl, and the Al2O3 scale which forms on it, have thermal expansion coefficients which are substantially more alike than any of the other oxide-metal combinations tested.
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  • 79
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 12 (1978), S. 215-225 
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; Fe-Ni alloys ; kinetics ; scale morphology ; EPMA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation of an Fe—19.34 wt. % Ni alloy in dry CO2 has been studied at 700—1000°C using thermogravimetry, metallography, and EPMA. Weight gains for oxygen consumption followed a linear-parabolic-linear sequence at all temperatures. During the initial linear stage the scale consisted mainly of magnetite and the activation energy of 133±25 kJ · mole−1 is considered to be due to dissociation of CO2 into CO and adsorbed oxygen on the outer magnetite surface. During the parabolic oxidation stage a continuous Ni-rich layer containing ∼ 70% Ni forms a barrier to the diffusion which has an activation energy of 192±79 kJ · mole−1. The breakdown of the barrier layer causes a return to linear kinetics with an activation energy of 138±42 kJ · mole−1 for dissociation of CO2 on the outer surface. During the final linear stage there is pronounced general and intergranular subscale formation. Detailed information is presented of the Ni redistribution and concentrations during oxidation and its correlation with the kinetics and morphology.
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  • 80
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 12 (1978), S. 35-66 
    ISSN: 1573-4889
    Schlagwort(e): CoCrAl ; oxidation ; oxide scale adherence ; rare-earth effect ; hafnium ; yttrium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The effect of small amounts of yttrium (up to 1 wt. %) and hafnium (up to 1.5 wt.%) on the oxidation behavior of Co-Cr-Al alloys in the temperature range 1000–1200°C for times up to 1000 hr in air has been studied. The major portion of the study has been concerned with Co-10Cr-11Al base alloys. Both isothermal and cyclic tests have been carried out; the cycle used consisted of 20 hr at temperature, followed by cooling to room temperature. Both additions reduce the overall oxidation, Hf somewhat more so than Y. In part, this is due to the improved adhesion between scale and alloy reducing scale spallation at temperature, and in part due to possible modification of the Al2O3 grain size. The former factor is far more critical under thermal cycling conditions. Under isothermal conditions the oxidation rate increases with increasing Hf content with all but the 1.5 wt.% alloy oxidizing more slowly than the Hf-free alloy; increase in Y content has the reverse effect. Under thermal cycling conditions the 0.3 and 1.0 wt.% Hf alloys show the lowest overall weight gain. Metallographic evidence suggests that the improved scale adhesion is due principally to a pegging mechanism; the active elements promote the growth of intrusions of Al2O3 into the alloy. However, if the intrusions are too large, they can act as initiators of scale failure.
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  • 81
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 12 (1978), S. 139-156 
    ISSN: 1573-4889
    Schlagwort(e): Rosenburg method ; oxidation ; CoO
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The Rosenburg continuous kinetic method is proposed for the determination of the parabolic rate constants of metal oxidation as a function of temperature and oxidant pressure. Using this method, it is possible to make numerous measurements in a continuous manner on a single metal sample left in situ in the furnace, thus eliminating systematic errors due to differences between samples. Moreover, using this method it is possible to determine directly from a given kinetic curve such important parameters as the coefficients of chemical diffusion and self-diffusion of the more mobile species in the studied compound and the total equilibrium defect concentration. The latter parameter has been inaccessible up to now by the experimental method. The limits of applicability of this method are given in the paper. As an example of this method, the kinetics of cobalt oxidation are investigated in the range of temperature 1000–1250°C and oxygen pressure 10−3−1 atm; the results compare favorably with those obtained by other authors. The method is, however, applicable to certain other systems, namely, metal oxides and sulfides.
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  • 82
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 12 (1978), S. 173-181 
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; hot corrosion ; sulfidation ; preoxidation ; scale penetration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The transport of sulfur through growing scales may occur by chemical (solution and diffusion) or physical (gas molecule permeation) mechanisms. Both possibilities are examined theoretically for the case of NiO growing on nickel. Experiments are designed and carried out to establish which mechanism plays the major role in sulfur transport. The results indicate that the physical mechanism is likely to be predominant.
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  • 83
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 13 (1979), S. 519-543 
    ISSN: 1573-4889
    Schlagwort(e): nickel ; oxidation ; transport ; tracer ; duplex scale
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Experimental techniques have been developed for determining Ni63 and O18 tracer distributions in NiO scales ranging in thickness from ∼0.1 to 100 μ. These have been used to investigate Ni and O transport in scales on {100} Ni crystals and polycrystalline Ni in the temperature range 500–1300° C. NiO grown on {100} Ni crystals at 1000°C was uniform and compact and grew by the bulk diffusion of Ni in NiO by a vacancy mechanism. At temperatures below 800°C the principal transport mechanism was short-circuit diffusion of Ni in NiO. At all temperatures short-circuit diffusion of oxygen contributed to scale growth on polycrystalline Ni and was responsible for growth of the inner layer of duplex scales. The oxygen diffusion paths are believed to be micro-cracks induced by growth stresses.
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  • 84
    Digitale Medien
    Digitale Medien
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    Oxidation of metals 13 (1979), S. 159-180 
    ISSN: 1573-4889
    Schlagwort(e): nickel-chromium alloys ; oxidation ; high temperature ; cerium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation behavior of Ni-50Cr alloys with minor cerium additions was studied between 800 and 1100° Cin oxygen, air, and oxygen at reduced partial pressures. Optical and scanning electron metallography, X-ray diffraction, and electron-probe microanalysis techniques were used to characterize the changes in scale and substrate morphology and to identify the oxidation products. Platinum markers were used to determine the direction of ionic transport. The effects of cold work, initial alloy phase distribution, and cyclic oxidation were also studied. The Cr 2 O 3 scales on the cerium-containing alloys grew while being largely separated from the metal substrate. Oxidation rate, oxide grain growth, and the tendency of scales to spall on cooling were reduced substantially with increasing alloy cerium content. The first two effects are suggested to result from the interaction of cerium ions and cerium oxide particles with oxide grain boundaries in reducing grain-boundary diffusion and oxide-boundary mobility. The third is suggested to result from the thinner, finer-grained scales formed on the Ce-containing alloys.
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  • 85
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 9 (1975), S. 99-116 
    ISSN: 1573-4889
    Schlagwort(e): oxidation ; kinetics ; ilmenite ; rutile ; pseudobrookite
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The oxidation of ilmenite (FeTiO3) in air and dry oxygen was investigated over the temperature interval 600 to 970°C. Dense platelets of ilmenite crystals as well as powder samples of ilmenite were oxidized. The weight data were recorded employing a thermobalance. The oxidation kinetics of ilmenite platelets were parabolic except for the initial stages during which logarithmic kinetics were observed. For powder samples the logarithmic rate law was followed primarily. The logarithmic rate law was attributed to free penetration of oxygen through cracks and short-circuit paths. The activation energies associated with the logarithmic rate law were nearly one-half of those obtained from parabolic oxidation. The growth morphology of the products of oxidation of ilmenite was observed with a scanning electron microscope. The effect of growth morphology on the kinetics is discussed, and a probable reaction mechanism is suggested for the oxidation of ilmenite.
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  • 86
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 1 (1975), S. 101-113 
    ISSN: 1573-1561
    Schlagwort(e): pheromone ; inhibition ; Scolytidae ; Ips ; pini ; paraconfusus ; ipsenol ; linalool
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The bark beetles,Ips pini andI. paraconfusus, are not cross-attractive in the field although they attack the same host material at the same time. Logs containing the pheromone-producing sex (males) of both species side by side attract significantly fewer beetles of each species than do males of either species alone. Ipsenol, a component of the maleI. paraconfusus pheromone, duplicates the activity of maleI. paraconfusus in inhibiting the response ofI. pini to maleI. pini. Linalool from maleI. pini also reduces the catch ofI. paraconfusus in response to maleI. paraconfusus. Simultaneous production of a specific attractant pheromone and an interspecific chemical inhibitor favors exclusive use of the host substrate by the first arriving species.
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  • 87
    ISSN: 1573-1561
    Schlagwort(e): Archips argyrospilus ; Archips mortuanus ; pheromone ; attractant ; Tortricidae ; (Z)-11-tetradecenyl acetate ; (E)-11-tetradecenyl acetate ; (Z)-9-tetradecenyl acetate ; dodecyl acetate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract MaleArchips argyrospilus (Walker) were maximally attracted to a 60∶40∶4∶200 admixture of (Z)-11-tetradecenyl, (E)-11-tetradecenyl, (Z)-9-tetradecenyl and dodecyl acetates. The identification of (Z)-9-tetradecenyl acetate, in addition to the other 3 components reported previously, is the first report of a 4-component pheromone system in moths.Archips mortuanus Kearfoot, a sibling species, was maximally attracted to a blend of the same components, but in a 90∶10∶1 mix of the tetradecenyl acetates. Among a number of tortricine moths that co-occur on apples and other hosts in New York, British Columbia, and elsewhere, differences in diel rhythms of attraction and seasonal distribution are insufficient to maintain reproductive isolation. Although the attractant systems of these species often possess components in common, males are maximally attracted to a speciesspecific blend. In tortricine moths attraction specificity appears to be a paramount mechanism for species partitioning.
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  • 88
    Digitale Medien
    Digitale Medien
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    Journal of chemical ecology 3 (1977), S. 133-141 
    ISSN: 1573-1561
    Schlagwort(e): pheromone ; inhibitor ; bark beetle ; Dendroctonus ; southern pine beetle ; slow-release formulations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract A slow release formulation of the bark beetle pheromones,endo- andexo-brevicomin, significantly reduced landing of southern pine beetles on host trees. Beetle flight activity within the infestation was not affected by the pheromones. The pheromones were released at approximately 600 mg/ha/day via Conrel® hollow fiber controlled-release dispensers.
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  • 89
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 3 (1977), S. 207-217 
    ISSN: 1573-1561
    Schlagwort(e): Black molly fish ; Mollinenesia latipinna ; pheromone ; thyroxine ; thiouracil ; general activity stimulus ; social contact
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The female black mollyMollinenesia latipinna emits a water-borne pheromone which increases general activity and social contacts among males. Two hormones, thyroxine and thiouracil, administered to the females increase these behaviors in males. Apparently the hormones do not functionally compete in this species, and both seem to elevate the emission of the male stimulant.
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  • 90
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 3 (1977), S. 245-249 
    ISSN: 1573-1561
    Schlagwort(e): stable fly ; Stomoxys calcitrans (L.) ; pheromone ; sex pheromone ; branched alkanes ; mating stimulant
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Each of 20 methyl-branched and 1,5-dimethyl-branched alkanes that comprise the active principle of saturated hydrocarbons of the female stable fly,Stomoxys calcitrans (L.), was synthesized and evaluated for mating stimulant activity. The compounds that showed the highest degree of activity in bioassays were 15-methyl- and 15,19-dimethyltritriacontanes.
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  • 91
    ISSN: 1573-1561
    Schlagwort(e): Fannia canicularis (L.) ; little house fly ; pheromone ; sex pheromone ; (Z)-9-pentacosene ; heneicosan-8-ol acetate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Chromatograms of the cuticular lipids washed from recently emerged female and maleFannia canicularis (L.) flies were nearly identical, but by the time the flies were 5 days old, the cuticular components of the two sexes differed considerably. A monoolefin which constituted 66% of the cuticular lipid from 5-day-old females stimulated a copulatory response from males and was identified as (Z)-9-pentacosene. The cuticular lipid of the same age males contained only 1% of this compound. Although all the major constituents of the cuticular lipid from mature females were hydrocarbons, 27% of the lipid washed from 5-day-old males was a nonhydrocarbon material that was represented by a single GLC peak. This material was identified as heneicosan-8-ol acetate.
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  • 92
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 3 (1977), S. 461-466 
    ISSN: 1573-1561
    Schlagwort(e): communication ; fish ; cichlid ; Cichlasoma citrinellum ; pheromone ; maternal ; development ; predation ; chemoreception ; fry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract When placed in aY-maze, the 1–10-day-old free-swimming fry of the Midas cichlid can chemically distinguish between their mother and plain water and between another mother and plain water. They do not distinguish between the two mothers offered together or between their father and plain water. Predation pressures make these responses adaptive.
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  • 93
    ISSN: 1573-1561
    Schlagwort(e): Scolytus multistriatus ; Dutch elm disease ; pheromone ; Multilure ; mass-trapping ; Ulmus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract We attempted to suppress a population ofScolytus multistriatus (Marsham), the principal vector of Dutch elm disease, by trapping flying beetles on sticky traps baited with synthetic pheromone. The estimated catch on 421 traps distributed throughout a 1-km2 plot in Detroit, Michigan, was nearly 1 million beetles. Because an estimated 5 million beetles emerged in the plot during the study period, we conclude that this preliminary trapping study had no appreciable effect on suppressing the population. Studies that employ improved materials and techniques are continuing.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 94
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 4 (1978), S. 409-423 
    ISSN: 1573-1561
    Schlagwort(e): Coleoptera ; Dermestidae ; diel behavioral patterns ; 14-methyl-8-hexadecenal ; pheromone ; reproductive isolation ; Trogoderma glabrum ; T. inclusum ; T. variabile ; trogodermal
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract AdultTrogoderma glabrum, T. inclusum, andT. variabile exhibit diel periods of exposure-concealment behavior, the frequency and duration of which are age-dependent, and the temporal placement of which is species-dependent. Exposure periods correspond with daily maxima in male sensitivity to the most active female-released sex pheromone component, 14-methyl-8-hexadecenal, and with respective periods of sex pheromone release in females. Exposure-concealment behavior may be a factor in reproductive isolation between these species, since potential communication distances are greatly reduced when either males or females are concealed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 95
    ISSN: 1573-1561
    Schlagwort(e): Neodiprion sertifer ; Pine saw-fly ; Hymenoptera ; Diprionidae ; pheromone ; trans-perillenal ; monoterpene
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Volatile constituents present in nanogram quantities in various body parts and glands of the males and females of the speciesNeodiprion sertifer Geoffr. (Hymenoptera: Diprionidae) have been investigated by GC-MS. A significant amount of a volatile constituent was detected in the lateral parts of the integument of abdominal segments II-III. The constituent was identified as the furanoid monoterpenetrans-perillenal (I) previously not known to occur in nature. The identification and synthesis of this compound is described.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 96
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 5 (1979), S. 353-361 
    ISSN: 1573-1561
    Schlagwort(e): Stable fly ; Stomoxys calcitrans (L) ; pheromone ; mating stimulants ; alkenes ; cuticular lipids ; copulatory behavior
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The cuticular alkenes of the female stable fly,Stomoxys calcitrans (L), which were responsible for inducing male fly copulatory behavior are (Z)-9-hentriacontene, (Z)-9-tritriacontene, 13-methyl-1-hen-triacontene and 13-methyl-1-tritriacontene. The identifications of the branched alkenes and the synthesis of these four compounds are described. Bioassays indicate that these materials in combination with previously described methyl branched alkanes are more active than the individual components.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 5 (1979), S. 565-574 
    ISSN: 1573-1561
    Schlagwort(e): Lepidoptera ; Lasiocampidae ; Malacosoma americanum ; Malacosoma disstria ; Tortricidae ; Archips cerasivoranus ; trail marker ; pheromone ; interspecific response ; tent caterpillar
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Exploratory trails deposited on paper strips by the forest tent caterpillar (FTC),Malacosoma disstria Hubner, and the eastern tent caterpillar (ETC),M. americanum (Fabricius), as well as extracts of these trails, readily elicited interspecific trail-following behavior. In 2-choice tests involving simple Y mazes constructed from these paper strips, the caterpillars of both species preferred by approximately 3∶1 the trails of the FTC. Studies involving whole colonies of the ETC maintained under nearnatural conditions in the laboratory, however, indicated that the trails deposited by successful foragers of the ETC as they returned to their tent from feeding sites were more attractive than the exploratory trails of either the ETC or FTC. The pronounced interspecific response of these congeners to each other's trails suggests that they utilize either qualitatively similar or identical trail-marking chemicals. Both species preferred their own trails to those ofArchips cerasivoranus (Fitch) (Tortricidae), providing the first evidence that more distantly related lepidopterous larvae utilize distinct trails.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 5 (1979), S. 941-953 
    ISSN: 1573-1561
    Schlagwort(e): White peach scale ; Pseudaulacaspis pentagona ; pheromone ; attractant ; microtechniques ; enantiomer ; isomers ; (R,Z)-3 ; 9-dimethyl-6-isopropenyl-3 ; 9-decadien-1-ol propionate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Micro techniques were used to obtain spectroscopic and degradative information from less than 5μg of the sex attractant of female white peach scale,Pseudaulascaspis pentagons (Targioni-Tozzetti) isolated from airborne collections. The pheromone was identified as (Z)-3,9-dimethyl-6-isopropenyl-3,9-decadien-1-ol propionate. Both enantiomers of theZ isomer and also the enantiomers of theE isomer were prepared from (R)-or (S)-limonene. Bioassays of material with minimum enantiomeric purity of 95% showed that at extreme dilution only theR,Z isomer attracted male white peach scale; however activity of theS,Z enantiomer could not be completely excluded.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    ISSN: 1573-1561
    Schlagwort(e): Coleoptera ; Dermestidae ; Trogoderma variabile ; pheromone ; isolation ; identification ; (Z)-14-methyl-8-hexadecenal ; aeration ; Porapak Q ; sex attractant
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Females of the dermestid beetle,Trogoderma variabile Ballion, exhibit a diel pattern of calling behavior. A potent sexual excitant and attractant for the male beetles can be collected on Porapak Q during aeration of female beetles, but cannot be detected in extracts of macerated females. The attractant has been identified as (Z)-14-methyl-8-hexadecenal. Of the five additional compounds previously identified as attractants in otherTrogoderma species, only two were found; (Z)-14-methyl-8-hexadecen-1-ol is present in extracts of macerated female beetles, but not in extracts of Porapak Q, and γ-caprolactone is present in extracts of Porapak Q. Three collection procedures were necessary to ensure that all the pheromone components had been isolated. Synthetic (Z)-14-methyl-8-hexadecenal elicits attraction and sexual arousal inT. Variabile males.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 3 (1977), S. 219-237 
    ISSN: 1573-1561
    Schlagwort(e): Attagenus elongatulus ; Dermestidae ; pheromone ; behavior ; calling ; bioassay
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Males ofAttagenus elongatulus Casey responded to a source of female odor with a characteristic sequence of actions which included: extension of the antennae, elevation of the body by leg extension, rapid zig-zag running, and intermittent bobbing up and down. The courtship sequence also consisted of several activities and was usually followed by a typical copulatory act of less than 1-minute duration. Virgin females exhibited calling behavior which was associated with pheromone release. Female calling activity, female pheromone content, and male responsiveness followed a diurnal cycle with peak values occurring during the earlier hours of the 16L∶8D photoperiod. Quantitative bioassay indicated that a 50% male response level (RD50) occurred at ca. 0.014 female equivalent (FE) exposure.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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