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  • Articles  (213)
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  • 1
    Electronic Resource
    Electronic Resource
    Effects of vegetation and weather on trap catches of Glossina fuscipes fuscipes near Lake Victoria, Kenya (1997)
    Springer
    Entomologia experimentalis et applicata 85 (1997), S. 231-236 
    Details
    ISSN: 1570-7458
    Keywords: Glossina fuscipes fuscipes ; vegetation ; biconical trap ; temperature ; light ; relative humidity ; monitor lizard
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glossina fuscipes fuscipes Newstead was sampled in isolated thickets and forest patches near Lake Victoria, Kenya using unbaited biconical traps, between March 1992 and June 1993. Traps set at 1 m from the forest edge caught 3.3 times as many males and 5 times as many females as those set inside or 10 m away. The corresponding figures at 1 m from the edge of thicket were about 1.43 and 1.64 times, respectively. Hourly catches of males and females were positively correlated with temperature, light intensity and host (monitor lizard) prevalence, and negatively correlated with relative humidity. Light intensity and temperature were the most important variables affecting the catches of each sex. The results are discussed in relation to control and monitoring of G. f. fuscipes using traps.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003179128955
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  • 2
    Electronic Resource
    Electronic Resource
    Choosing a place to grow. Importance of within-plant abiotic microenvironment for Yponomeuta mahalebella (1997)
    Springer
    Entomologia experimentalis et applicata 83 (1997), S. 171-180 
    Details
    ISSN: 1570-7458
    Keywords: within-plant heterogeneity ; tent caterpillars ; temperature ; circular statistics ; Lepidoptera ; Yponomeutidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The caterpillars of Yponomeuta mahalebella Latr. (Lepidoptera: Yponomeutidae) are monophagous on Prunus mahaleb (Rosaceae) leaves. Adult females deposit eggs in batches, which determines larval gregarious behaviour. Coupled with gregarious behaviour, caterpillars spin silk tents within they will feed until pupation. Distribution of tents in the field, their effect in microenvironmental larval growth conditions and the consequences for adult body mass and survival of larvae were studied. There was a significant trend for tents to be placed with a southward orientation. Within-plant tent orientation was related to the sun-shade pattern experienced, which was the main effect determining thermal differences between the inside and the outside of the tent. These differences appeared to affect larval growth and survival, with higher survival of larvae and heavier adults emerging from tents oriented to the south-east and east, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002908817924
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  • 3
    Electronic Resource
    Electronic Resource
    Magnetometric Method of Investigating Fire Sites (1997)
    Springer
    Fire technology 33 (1997), S. 195-213 
    Details
    ISSN: 1572-8099
    Keywords: point of fire origin ; fire ; temperature ; plaster ; concrete ; thermal ; damage ; biotite ; magnetization ; susceptibility ; N-rays ; P-rays ; X-rays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract Magnetic susceptibility (MS) measurements were taken to determine fire exposure patterns on noncombustible structural members and compartment boundaries. These measurements led on-site fire investigators to the cause of combustion and the point of fire origin. Thermal damage to walls and to ceilings was estimated quantitatively by measuring MS and two-valent Fe ion concentration in building materials such as concrete and plaster. It was shown that these effects are preconditioned by thermochemical transformations in the mineral biotite, which is present as a component of common building materials. For the first time, the effect of a substantial and irreversible increase in biotite magnetization exposed to powerful flows of N- and P-rays was found. It is hoped that the presence of this “magnetic trace” of radiation in building materials will allow investigators to use the magnetometric method at nuclear power plant catastrophes such as that in Chernobyl. It was also shown that the influence of N- and P-rays on biotite's magnetic properties greatly differs from the thermal influence on biotite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015363605037
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  • 4
    Electronic Resource
    Electronic Resource
    Reproduction of Diaeretiella rapae on Russian wheat aphid hosts at different temperatures (1997)
    Springer
    Entomologia experimentalis et applicata 82 (1997), S. 159-166 
    Details
    ISSN: 1570-7458
    Keywords: Diaeretiella rapae ; reproduction ; life-tables ; temperature ; Diuraphis noxia ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Diaeretiella rapae (M'Intosh), a polyphagous and cosmopolitan parasite of aphids, was imported from China to the USA for biological control of Diuraphis noxia (Mordwilko), a pest of small grains. We studied several aspects of its biology on D. noxia hosts in the laboratory at 3 constant temperatures, 10.0, 21.1, and 26.7 °C. Females lived significantly longer than males at all 3 temperatures, and longevity was greatest at 10 °C, followed by 21.1 and 26.7 °C. Fecundity (= number of mummies) did not differ significantly among the 3 temperatures studied. The ovarian egg-load was 129.1 ± 9.3, and was significantly affected by the size of adult females. A pre-oviposition period ± 0.26 days) was detected at 10 °C, but not at the other temperatures. Pre-imaginal survivorship was similar among temperatures, while R o and T c decreased with temperature, and r m increased with temperature. The offspring sex ratio (proportion females) was lowest at 26.7 °C, and similar between 10.0 and 21.1 °C. In addition, the offspring sex ratio significantly declined with the age of the female parent. The suitability of D. rapae for colonization against D. noxia in North America is discussed in relation to its responses to temperature and the climate of its home range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002929500786
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of light availability on host plant chemistry and the consequences for behavior and growth of an insect herbivore (1997)
    Springer
    Entomologia experimentalis et applicata 82 (1997), S. 319-333 
    Details
    ISSN: 1570-7458
    Keywords: chlorogenic acid ; light availability ; Lycopersicon esculentum ; Manduca sexta ; protein ; rutin ; temperature ; tomatine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examined how light availability influenced the defensive chemistry of tomato (Lycopersicon esculentum: Solanaceae). Tomato plants were grown either in full sunlight or under shade cloth rated at 73%. Leaves from plants grown in full sunlight were tougher, had higher concentrations of allelochemicals (chlorogenic acid, rutin and tomatine), and had less protein than leaves from plants grown in shade. We determined how these differences in host plant quality due to light availability affected the behavior and growth of a Solanaceae specialist, Manduca sexta. Both in the greenhouse and in the field, caterpillars on shade-grown plants grew heavier in a shorter amount of time than those on plants that had previously been grown in full sunlight. In contrast, the effects of previous light availability to plants on caterpillar behavior appeared to be minor. To further investigate how light availability to plants influenced herbivore growth, we examined the effects of leaf-powder diets made from tomato leaves of different ages (new, intermediate, or mature) grown in full sunlight or shade on caterpillar performance. Caterpillars fed diets made from plants grown in shade consumed less but grew faster than larvae fed diets made from tomato plants grown in full sunlight. Caterpillars fed diets made from new leaves grew larger in less time than caterpillars fed diets made from intermediate aged leaves. Caterpillars did not survive on the mature leaf powder diets. There were plant-light treatment by larval thermal regime interactions. For example, at 26:15 °C , plant-light treatment had no effect on stadium duration, but at 21:10 °C, stadium duration was prolonged with the full sunlight-new leaf diet compared with the shaded-new leaf diet. In a second diet experiment, we examined the interactive effects of protein and some tomato allelochemicals (rutin, chlorogenic acid and tomatine) on the performance of caterpillars. There were food quality by thermal regime interactions. For instance, at 26:15 °C , neither protein nor allelochemical concentration influenced stadium duration, whereas at 21:10 °C, stadium duration was prolonged with the low protein-high allelochemical diet, which simulated full sunlight leaves. In sum, light availability to plants affected defensive chemistry and protein concentration. The difference in food quality was great enough to influence the growth of a specialist insect herbivore, but the effects were temperature-dependent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002916325052
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  • 6
    Electronic Resource
    Electronic Resource
    Inter- and intra-population differences in the effects of temperature on postdiapause development of Delia radicum (1997)
    Springer
    Entomologia experimentalis et applicata 84 (1997), S. 255-265 
    Details
    ISSN: 1570-7458
    Keywords: Delia radicum ; postdiapause development ; temperature ; Diptera ; Anthomyiidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Canadian populations of D. radicum differ in their response to temperature during postdiapause development. Populations that are primarily of the early-emerging type ( $$\left( { \leqslant 256DD_{04} } \right)$$ ) (St-Jean, Quebec; London, Ontario) have high values for the parameters describing this response: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOuamaaBa% aaleaacaWGTbaabeaakiabg2da9aaa!38F2!$$R_m = $$ 12.7–13.3; $$T_m = $$ 28.0–31.8 °C ; Tσ = 10.3–14.2 ( $$R_m $$ , the maximum developmental rate at the temperature, $$T_m $$ [ °C ] where the developmental rate is highest, and Tσ , the parameter which gives the shape of the truncated normal curve fitted to the data), a low degree-day requirement for emergence (160–232 $$DD_{04} $$ ), and may lack a developmental delay at temperatures above ca. 21 °C . Populations of the late-emerging type (Kildare, Prince Edward Island) have low parameter values ( $$ R_m = 2.5$$ , $$T_m = 19.3$$ °C ; Tσ = 6.4), high degree-day requirements (530 $$DD_{04} $$ ), and a developmental delay at high temperatures. The parameters for the early-emergers in the population from Winnipeg, Manitoba (74% early) were intermediate ( $$R_m = 9.1$$ , $$T_m = 27.1$$ °C , Tσ = 10.7, $$ DD_{04} = 246 $$ ), but resembled the early rather than the late type. This population varied from 31 to 90% early type over a 10-year period and the rate of postdiapause development at 20 °C was directly related to the percentage early. In the year with the most rapid development (90% early), development was significantly slower than in the populations from other locations with predominantly early populations, and the year with the slowest development (31% early) showed significantly faster development than that from Kildare, Prince Edward Island (100% late). Therefore the parameters for early and late types of development will not be accurate for use in mixed populations, and the parameters in mixed populations will change among years. Populations of D. radicum in North America and Europe (67 locations by years) varied from 0–100% early. At Winnipeg, the percentage early was directly related to the annual temperature accumulation ( $$DD_{05} $$ ) during the growing season. The calculation of developmental parameters for the early-emergers of mixed populations provides a more accurate basis for estimating the times of first emergence and the first peak of emergence than parameters based on the whole population. Since postdiapause developmental rates vary both among and annually within locations, developmental models should be designed to include such variations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003048502446
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  • 7
    Electronic Resource
    Electronic Resource
    Carbon monoxide electrooxidation on porous Pt–Ru electrodes in sulphuric acid (1997)
    Springer
    Journal of applied electrochemistry 27 (1997), S. 1275-1282 
    Details
    ISSN: 1572-8838
    Keywords: Carbon monoxide ; Pt-Ru/C catalyst ; Tafel slopes ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract CO electrooxidation on a Pt–Ru/C catalyst was investigated in sulphuric acid electrolyte. The physico-chemical properties of the Pt–Ru/C catalyst were studied by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The influence of temperature, CO partial pressure and proton concentration on the electrochemical oxidation rate was investigated by steady-state galvanostatic polarization measurements. The apparent activation energy decreased from 70 to 30kJmol−1 as the overpotential increased from 0.5 to 0.9V vs NHE. The reaction order with respect to carbon monoxide increased, passing from 0.4 to 1, with the increase of the overpotential from 0.5 to 0.7V vs NHE; a reaction order close to −1 with respect to the protonic concentration was observed, irrespective of the potential. Tafel slopes of about 136mVdec−1 were determined for oxidation of CO and CO/N2 mixtures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018492122263
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of temperature on performanceof LaNi4.76Sn0.24 metal hydride electrode’ (1997)
    Springer
    Journal of applied electrochemistry 27 (1997), S. 1328-1332 
    Details
    ISSN: 1572-8838
    Keywords: metal hydride ; capacity ; temperature ; performance ; enthalpy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The effect of temperature on the performance of a LaNi4.76Sn0.24 metal hydride electrode was investigated in the temperature range of 0 to 50°C. The electrode showed a maximum discharge capacity at 25°C. The total resistance increases with a decrease of temperature from 50°C to 0°C. The apparent activation enthalpies at different states of charge were determined by evaluating the polarization resistance at different temperatures. It was found that the apparent activation enthalpy is an indicator of the relative reaction rate of the charge-transfer reaction and hydrogen absorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018460709968
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  • 9
    Electronic Resource
    Electronic Resource
    Preparation and characterization of bimodal porous carbons derived from a styrene-divinylbenzene copolymer (1997)
    Springer
    Adsorption 3 (1997), S. 67-79 
    Details
    ISSN: 1572-8757
    Keywords: porous carbons ; activation ; oxidation ; surface oxygen groups ; LTPD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A styrene/divinylbenzene copolymer has been used as precursor for making porous carbons with bimodal pore size distributions (i.e., with both microporosity and mesoporosity). Pretreatment of the as-received copolymer by mild oxidation in air, significantly increased the carbon yield after carbonization. Reactivity studies of the polymer-based chars to CO2 clearly show the influences of some important factors such as carbonization temperature, heating rate, soak time on char reactivities. Bimodal porous carbons were prepared by carbonization of the preoxidized styrene/divinylbenzene copolymer in N2, followed by activation in CO2 at different temperatures to different levels of burnoff. The pore structures of the porous carbons produced have been characterized by various techniques such as gas adsorption and mercury porosimetry. The surfaces of the porous carbons produced, and a commercial carbon adsorbent, have been modified with HNO3 and H2O2 treatment at various conditions. Characterization of the surface oxygen functionality, both quantitatively and qualitatively, has been achieved using techniques such as Linear Temperature Programed Desorption (LTPD) and selective neutralization of bases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01133008
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  • 10
    Electronic Resource
    Electronic Resource
    The Influence of Catalyst Composition on the Oxidation Process of Carbonado Type Synthesized Polycrystalline Diamonds (1997)
    Springer
    Advanced performance materials 4 (1997), S. 297-304 
    Details
    ISSN: 1572-8765
    Keywords: carbonado ; diamond ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of carbonado type synthesized polycrystalline diamonds produced from graphite together with catalytic Ni-Mo alloy doped with TiB2 and BNcub was investigated. It was found that the addition of these boron compounds increases the oxidation resistance of the carbonado type synthesized polycrystalline diamonds. The oxidation mechanism acting on the carbonado type synthesized polycrystalline diamonds and the role of boron compounds in increasing the resistance to the oxygen reaction are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008677105534
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  • 11
    Electronic Resource
    Electronic Resource
    Effect of fluorination of alumina support on activity of platinum catalysts for complete oxidation of benzene (1997)
    Springer
    Catalysis letters 49 (1997), S. 155-161 
    Details
    ISSN: 1572-879X
    Keywords: fluorination ; alumina ; platinum catalysts ; oxidation ; oxidation of benzene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Platinum supported on fluorinated alumina is more active for the total oxidation of benzene than is the catalyst with the same Pt loading supported on hydrophilic unfluorinated alumina. The Pt-F/alumina catalyst contains well-dispersed small Pt particles, in contrast to Pt/alumina. The high dispersion is a consequence of a strong metal-support interaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019065507551
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  • 12
    Electronic Resource
    Electronic Resource
    Étude des principaux facteurs influençant l'émission d'attractifs sexuels synthétiques à partir de diffuseurs en caoutchouc et en plastique (1987)
    Springer
    Entomologia experimentalis et applicata 44 (1987), S. 123-130 
    Details
    ISSN: 1570-7458
    Keywords: composantes phéromonales ; diffusion ; température ; vent ; Z9-12:Ac ; 12:Ac ; Z9-14:Ac ; pheromonal components ; diffusion ; temperature ; wind ; Z9-12:Ac ; 12:Ac ; Z9-14:Ac
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Summary To determine the effect of various factors influencing the emission rate of pheromones from slow release dispensers, laboratory tests were undertaken with two types of rubber (Michelin) and one type of plastic trilaminate (Hercon®) dispenser. The effects of chain length, and the presence of double bonds were tested with three pheromonal compounds, Z9-12: Ac, 12: Ac and Z9-14: Ac impregnated on both types of rubber dispenser. The influences of temperature, wind velocity, humidity and percent loading were also tested. Data obtained indicated that chain length has a greater effect than the presence of a double bond. Amongst the climatic factors tested, wind speed has a greater effect than temperature while humidity has a minimal effect.
    Notes: Abstract Deux types de diffuseurs en caoutchouc (Michelin) et en plastique polystratifié (Hercon®) sont testés en laboratoire pour étudier quelques aspects des phénomènes de diffusion. Trois composantes phéromonales, le Z9-12: Ac, le 12: Ac et le Z9-14: Ac imprégnées dans ces différents supports servent à détermineer le rôle joué par la longueur de la chaîne de la molécule et la présence de doubles liaisons sur la vitesse de diffusion. L'influence de la température, de la vitesse du vent et de l'humidité est déterminée en cellules climatisées. Parmi les facteurs relatifs à la structure chimique, l'influence de la longueur de la chaîne est prédominante par rapport à la présence d'une double liaison. Parmi les facteurs climatiques, le vent agit plus que la température sur la diffusion, alors que l'humidité paraît secondaire.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00367619
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  • 13
    Electronic Resource
    Electronic Resource
    Regulation of body size in a heteropteran bug, Pyrrhocoris apterus (1987)
    Springer
    Entomologia experimentalis et applicata 44 (1987), S. 257-262 
    Details
    ISSN: 1570-7458
    Keywords: Heteroptera ; Pyrrhocoris apterus ; adult size ; egg weight ; starvation ; temperature ; pollution ; crowding ; duration of development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Die Körpergrösse bei den Imagines eines Wildstammes der Feuerwanze Pyrrhocoris apterus wurde teilweise durch die Veränderlichkeit der Eigrösse determiniert, teilweise auch durch Hungern der Larven, niedrige Temperatur und metabolischen Produkten beeinflusst. Der Effekt letzterer Faktoren stieg mit deren Dauer und war je grösser desto näher sich die Wirkungsperiode zur Imaginalhäutung befand. Unterschiedliche Photoperioden wirkten auf die Körperlänge nicht. Wurden die Larven zwischen der ungünstigen Periode und der Imaginalhäutung noch den optimalen Bedingungen ausgesetzt, kompensierten sich die negativen Einflüsse weitgehend. Zu einer drastischen Verkleinerung der Imagines kam es nur, wenn das letzte Larven-stadium mit Hunger beeinflusst wurde und bis zur Imaginalhäutung keinen Zutritt zum Futter hatte. Minimales Gewicht, wo die Metamorphose der Larven noch möglich war, wurde zu 18 mg festgestellt.
    Notes: Abstract The determination of body size (length or weight) of teneral adults of Pyrrhocoris apterus L. was investigated. About 50% of size variation was determined already in the egg stage (average egg weight adult length correlations were 0.67 in males and 0.71 in females). During the larval development, starvation, low temperature, and pollution by excreta combined with crowding reduced adult size and usually increased the development length. The effects were directly proportionate to the length of the stress period, and increased with larval age. Photoperiod or intrinsic variation of development time did not affect adult size. The effects of stress were largely compensated when it was followed by a period of compensation growth at optimum conditions. A dramatic reduction of size appeared when last inster larvae starved and moulted to adults without access to food. Average adult weight was then reduced by up to 48%. Threshold weight for adult moulting was 18 mg, being attained after 1–2 day feeding of the last instar.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00369187
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  • 14
    Electronic Resource
    Electronic Resource
    Survival of repeated frosts by the Queensland fruit fly, Dacus tryoni: experiments in laboratory simulated climates with either step or ramp fluctuations of temperature (1987)
    Springer
    Entomologia experimentalis et applicata 45 (1987), S. 9-16 
    Details
    ISSN: 1570-7458
    Keywords: Dacus tryoni ; fruit fly ; frosts ; cold ; survival ; winter ; step ; ramp ; cooling ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé L'aptitude à survivre à une ou plusieurs expositions à des températures inférieures à zéro dépend à la fois de leur sévérité et du laps de temps entre les expositions. L'effet d'une température minimale déterminée dépend de sa valeur, de sa durée et du type de refroidissement: brutal (step) ou progressif (ramp). Les effets de toute température minimale peuvent être exprimés en termes de LE50 (temps nécessaire pour obtenir une mortalité de 50% avec une exposition unique). Lorsque le temps d'application de la température minimale correspond à 35% du LE50, il n'y a pas de mortalité, de même dans le cas de répétitions quotidiennes. Lorsque le minimum est subi pendant 44% du LE50, il provoque environ 14% de mortalité après la première exposition, avec 3% supplémentaire après chaque exposition quotidienne, mais l'augmentation est nulle si l'exposition au froid n'a lieu que tous les 3 jours. Lorsque le minimum est subi pendant 88% de LE50, la mortalité après la première exposition est d'environ 40% et de même importance à chaque nouvelle exposition, même si elles sont espacées de 7 j. Lorsque la durée d'exposition au minimum correspond à 125% et à 150% de LE50, les mortalités sont respectivement d'environ 80% et 100% à la première exposition. La température maximale quotidienne, entre 15 et 25°C, semble avoir peu d'influence sur la mortalité provoquée par des expositions répétées à-5°C. Les mouches d'âges différents résistent de la même façon jusqu'à 6 expositions répétées à-6°C, mais au-delà les mouches âgées sont plus sensibles que les jeunes. Dans la mesure où, dans la nature, la durée d'exposition à la température minimale est connue et où la température dans le sol peut être calculée ou mesurée, ces résultats peuvent permettre d'interpréter la mortalité provoquée par le gel.
    Notes: Abstract Ability to survive exposure to single or repeated periods at a subzero temperature is related to the temperature experienced, whether it is approached quickly or slowly, the time for which it prevails and the interval between exposures. The severity of any low temperature can be expressed in terms of LE50 (time required to kill 50% of individuals with one exposure). Minima enduring for 35% LE50 do not cause any mortality, even when repeated daily. Minima enduring for 44% LE50 cause ca 14% mortality on the first occurrence but no more if repeated at 3 day intervals, but 3% more per occasion if repeated daily. Minima enduring for 88% LE50 cause ca 40% mortality on first occurrence and an equal amount at each recurrence even if each is 7 days apart. Minima enduring for 125% LE50 and over 150% LE50 cause respectively ca 80% and 100% mortality respectively on first occurrence. The daily maximum temperature (in the range 15°C to 25°C) appears to have little relevance to the mortality caused by a repeated minimum of -5°C. Flies of different ages have a similar ability to survive a repeated minimum of -6°C for up to six exposures, but thereafter old flies are more susceptible than young ones. These results can be related to mortality caused by frosty conditions in the field so long as the time spent at the minimum is known and the temperature on the ground can be measured or calculated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00343619
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  • 15
    Electronic Resource
    Electronic Resource
    Effect of temperature on the duration of larval and pupal stages of two species of sciomyzid flies, predators of the snail Lymnaea truncatula (1987)
    Springer
    Entomologia experimentalis et applicata 43 (1987), S. 95-100 
    Details
    ISSN: 1570-7458
    Keywords: Ilione albiseta ; Pherbellia cinerella ; Diptera ; Sciomyzidae ; larva ; pupa ; temperature ; Lymnaea truncatula ; snails ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé L'action de la température a été examinée à 14, 17, 20, 23 et 26°C. Les 2 espèces sont prédatrices de L. truncatula, vecteur de la douve du foie en Irlande, où elle provoque à l'àgriculture une perte évaluée à 10 millions de livres par an. Les données recuellies en conditions contrôlées du laboratoire doivent permettre de définir les conditions optimales pour l'élevage continu de ces espèces. Ceci est indispensable pour évaluer, dans la nature leurs potentialités pour la lutte biologique. Ilione albiseta: C'est à 23°C que le développement des larves de premier et second stades sont les plus brefs; la survie du premier stade est totale à toutes les températures constantes examinées. La durée moyenne du 3ème stade décroît de 104 jours à 17°C jusqu'à 27,5 jours à 26°C. Le taux de survie total est plus élevé à 17°C qu'à 26°C. La durée moyenne de la nymphose diminue quand la température croît, et ceci se produit aussi à la température ambiante extérieure. On réduit de moitié la durée du développement de l'éclosion de l'oeuf à l'apparition de l'adulte, entre la nature et le laboratoire, en utilisant respectivement: 23°, 17° et 26°C pour les premier et second stades, le troisième stade, la nymphé. Cela devrait aider à multiplier la souche pour la lutte biologique. Pherbellia cinerella: Avec élévation de la température la durée du développement larvaire diminue, mais aussi le nombre de larves parvenant à la pupaison (100% à 14° et 33,3% à 26°C). La nymphose tendait à être plus brève aux températures les plus élevées.
    Notes: Abstract The duration of larval and pupal stages of two species of predatory flies was investigated at five constant temperatures. Ilione albiseta (Scopoli): Mean duration of first and second instars was shortest at 23°C and there was 100% survival of first instar larvae at all temperatures. Mean third instar larval duration decreased from 104 days at 17°C to 27.5 days at 26°C. Total percentage larval survival was greatest at 17°C and least at 26°C. Mean pupal duration decreased as temperature increased and this occurred also under outdoor conditions. Pherbellia cinerella (Fallén): As temperature increased mean larval duration decreased but the percentage of larvae pupating also decreased (100% at 14°C, 33.3% at 26°C). There was a trend for shorter mean pupal durations at higher temperatures.
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    Effect of time-dependent speed on frictional heat generation and wear in transient axisymmetrical contact of sliding (1997)
    Springer
    Archive of applied mechanics 67 (1997), S. 331-338 
    Details
    ISSN: 1432-0681
    Keywords: Key words frictional heating ; wear ; contact pressure ; temperature ; brake system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary A transient contact problem with frictional heating and wear for two nonuniform sliding half-spaces is considered. One of the two half-spaces is assumed to be slightly curved to give a Hertzian initial pressure distribution: the other is a rigid nonconductor. Under the assumption that the contact pressure distribution could be described by Hertz formulas during all the process of interaction, the problem is formulated in terms of one integral equation of Volterra type with unknown radius of contact area. A numerical solution of this equation is obtained using a piecewise-constant presentation of an unknown function. The influence of operating parameters on the contact temperature and the radius of the contact area is studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004190050121
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    Short-term dynamics in protein and amino acid metabolism (1997)
    Springer
    European journal of nutrition 36 (1997), S. 336-339 
    Details
    ISSN: 1436-6215
    Keywords: Amino acids ; protein ; metabolism ; meal feeding ; oxidation ; breath test ; Aminosäuren ; Protein ; Stoffwechsel ; Fütterung ; Oxidation ; Atemtest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Die aktuellen Mengen an freien Aminosäuren im Blut reichen nur aus, um die Ganzkörper-Proteinsynthese für einige Minuten aufrecht zu erhalten. Das zeigt, daß die freien Aminosäurenkonzentrationen in der Zirkulation klein und konstant gehalten werden im Vergleich zu den Mengen der Aminosäuren, die täglich aufgenommen und über die Körperproteine umgesetzt werden. Das Verschwinden der Aminosäuren exogenen oder endogenen Ursprungs aus dem freien Aminosäuren-Pool, findet hauptsächlich durch die Proteinsynthese und den Aminosäurenabbau statt. Die Partitionierung der Nahrungs-Aminosäuren zwischen diesen beiden Prozessen im Kurzzeitbereich werden als bedeutsam für die Ökonomie der Ganzkörper-Aminosäuren angesehen. Eine Verbesserung der Aminosäurenökonomie könnte durch solche nutritiven Maßnahmen erreicht werden, welche die Clearance der Nahrungsaminosäuren durch die Proteinsynthese anstelle des Aminosäurenabbaus begünstigen. Diese nutritiven Maßnahmen sollten sich an den „Schwellenwerten“ des Abbaus der individuellen Aminosäuren orientieren.
    Notes: Summary Actual amounts of free amino acids in the blood are sufficient to support whole body protein synthesis for some minutes only. This indicates that the levels of free amino acids in the circulation are kept small and constant relative to the amounts of amino acids supplied by daily intake and turnover of body proteins. The clearance of the amino acids originating from either endogenous or exogenous sources is mainly due to protein synthesis and metabolic degradation. The partitioning of dietary amino acids between these processes, on the short term, is supposed to play an important role in whole body amino acid economy. Therefore whole body amino acid economy could be improved by nutritional measures that favour the clearance of dietary amino acids by protein synthesis instead of by metabolic degradation. These nutritional measures should to be focused on threshold values for metabolic degradation of individual amino acids.
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    URL: http://dx.doi.org/10.1007/BF01617818
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    C60: A host lattice for the intercalation of oxygen? (1997)
    Springer
    Microchimica acta 125 (1997), S. 401-406 
    Details
    ISSN: 1436-5073
    Keywords: fullerenes ; intercalation ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The investigation of structural and electronic properties of the novel family of fullerenes depends on the existence of pure reference materials. Sublimation of the van-der Waals solids is a suitable purification method. Little attention has been paid to the question about the air stability of such sublimed samples in form of crystals or thin films. A combination of thermal desorption spectroscopy, thermal analysis and diffuse reflectance FT-IR spectroscopy is used to show the extent to which oxygen from dry air is intercalated into fullerenes and which detrimental reactivity occurs from attempts to thermally remove („nneal”) air-exposed samples. The conclusion is that any fullerene sample exposed to air will be transformed in part into a polymeric non-fullerene carbon upon thermal treatment to above 400 K irrespective of its initial purity.
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    URL: http://dx.doi.org/10.1007/BF01246218
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    Effect of environmental conditions and inoculum density on infection of guava fruits by Colletotrichum glososporioides (1997)
    Springer
    Mycopathologia 137 (1997), S. 165-172 
    Details
    ISSN: 1573-0832
    Keywords: Anthracnose ; guava ; Colletotrichum glososporioides ; temperature ; free moisture ; inoculum density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The influence of environmental factors (temperature and humidity), inoculum density on infection by Colletotrichum glososporioides and development of anthracnose lesions were determined on uninjured, sand-injured and punctured fruits. The optical temperature for severe infection was 30 °C, whereas the disease incidence was less at 20 and 35 °C. Inoculated guavas that received 1–60 h of continuous free moisture developed lesions, but the disease was minimal (0–7%) after 1–6 h free moisture. Infection rates of uninjured, sand-injured and punctured fruits receiving 60 h of free moisture were 34, 70 and 100%, respectively. Disease incidence increased as inoculum density increased from 101 to 106 conidia/ml. In field conditions, the development of anthracnose lesions was greater on punctured guavas than on uninjured or sand-injured ones, in both rainy and winter seasons. In general, the number of lesions was highest in sand-injured fruits, followed by punctured and uninjured fruits. In rainy season the number of lesions on injured and uninjured fruits was greater than similarly treated guavas in winter.
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    URL: http://dx.doi.org/10.1023/A:1006842801828
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    Effect of temperature on antagonistic and biocontrol potential of shape Trichoderma sp. on Sclerotium rolfsii (1997)
    Springer
    Mycopathologia 139 (1997), S. 151-155 
    Details
    ISSN: 1573-0832
    Keywords: Antagonism ; biocontrol ; ginger ; postharvest rot ; Sclerotium rolfsii ; Trichoderma ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Sclerotium rolfsii is a destructive soil-borne and postharvest plant pathogen. Use of the antagonistic fungus Trichoderma sp. has been earlier reported by us to successfully control this pathogen under postharvest conditions. In the present paper we report on the effects of temperature on the growth and biocontrol potential of Trichoderma sp. on S. rolfsii. Experimental results indicated that S. rolfsii and Trichoderma sp. have different temperature optima for growth: 30–35 °C for the pathogen and 25–30 °C for the antagonist. In dual culture, Trichoderma overgrew S. rolfsii at 25 °C and 30 °C, but at 35 °C and 37 °C, S. rolfsii overgrew the colony of Trichoderma. Trichoderma produced higher concentration of fungitoxic metabolites in broth culture at higher temperatures. In bioassays using ginger slices and whole rhizomes, it has been demonstrated that Trichoderma is not very effective in suppressing S. rolfsii at temperatures above 30 °C. In light of these results, possible mechanisms of biocontrol of S. rolfsii as a postharvest pathogen has been discussed. Storage temperature has been suggested as a critical factor in biocontrol of S. rolfsii.
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    URL: http://dx.doi.org/10.1023/A:1006868009184
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    Urea, ammonium sulfate and dicyandiamide transformations in Costa Rican soils (1987)
    Springer
    Nutrient cycling in agroecosystems 12 (1987), S. 255-261 
    Details
    ISSN: 1573-0867
    Keywords: nitrification ; nitrification inhibitor ; fertilizer N ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The transformations of urea, ammonium sulfate and dicyandiamide (DCD) were studied in an Inceptisol and three Andisols from Costa Rica, considering the influence of temperature and DCD as a nitrification inhibitor. Nitrification was very slow with or without DCD in the strongly acid Inceptisol. A higher urea dose resulting in higher pH was well nitrified without DCD and appreciably retarded by DCD. In Andisols nitrification was retarded as long as a higher DCD level existed. Higher temperatures accelerated the DCD-breakdown and were followed by a quicker nitrification. The decomposition of DCD was slower compared with the Inceptisol. According to these experiments DCD is suitable as a nitrification inhibitor in tropical soils.
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    URL: http://dx.doi.org/10.1007/BF01315109
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    Evaluation and model of temperature and rainfall effects on response to N sources applied to grassland in spring (1987)
    Springer
    Nutrient cycling in agroecosystems 13 (1987), S. 255-267 
    Details
    ISSN: 1573-0867
    Keywords: urea ; ammonium nitrate ; model ; temperature ; rainfall ; grassland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Direct and residual effects of urea and calcium ammonium nitrate (CAN) on dry matter (DM) response were measured at a total of 12 application times in early spring over three years. The variation in the direct effect was described by models that included temperature and long-term rainfall for CAN and, additionally, short-term rainfall for urea. The operative temperature was the accumulated mean daily air temperature for combined intervals pre-application and postapplication of N. The effect of rainfall was apparent only when the data were adjusted for temperature. Simulation studies with the models indicated that, although the influence of temperature was dominant, rainfall modified it strongly in terms of the relative efficiencies of the two N sources and the magnitude of response. For instance, the temperature-induced increase in DM response to urea between cold and normal years was 402 kg ha−1 for a specified period, whereas differences between dry and wet years were decreases of 166 and 259 kg ha−1 in the case of urea and CAN, respectively. Short-term rainfall had a positive effect on response to urea. The experimental values varied widely both between and within years. The direct effect of the application of urea at 50 kg N ha−1 varied from 0 to 750 kg DM ha−1, and the residual effect varied from 0 to 1620 kg DM ha−1. The corresponding values for apparent N recovery varied from 0.1 to 45% and from 7 to 68%, respectively. The efficiency of urea was comparable to, and in instances better than, CAN.
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    Methane oxidation in soils with different textures and land use (1997)
    Springer
    Nutrient cycling in agroecosystems 49 (1997), S. 91-95 
    Details
    ISSN: 1573-0867
    Keywords: greenhouse effect ; land use ; methane ; oxidation ; soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Intact core samples from soils with different textures and land use were tested for their capacity to oxidise methane. The soil cores were taken from arable land, grassland and forest. It was found that coarse textured soils (6.74–16.38 µg CH4 m-2 h-1) showed a higher methane uptake rate than fine textured soils (4.66–5.34 µg CH4 m-2 h-1). Increasing soil tortuosity was thought to reduce the methane oxidation rate in fine textured soils. The oxidation rate of forest soils (16.32–16.38 µg CH4 m-2 h-1), even with a pH below 4.5, was very pronounced and higher than arable land (11.40–14.47 µg CH4 m-2 h-1) and grassland (6.74–9.30 µg CH4 m-2 h-1). Within the same textural class arable land showed a faster methane uptake rate than grassland. In grassland with a fine texture, even methane production was observed. Nitrogen availability and turnover in these land use systems were thought to cause the different oxidation rates. Decreasing the moisture content slowed down the oxidation rate in all soils. This could be caused by an increased N turnover and a starvation of the methanotrophic bacteria.
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    URL: http://dx.doi.org/10.1023/A:1009706324386
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    The effect of agriculture on methane oxidation in soil (1997)
    Springer
    Nutrient cycling in agroecosystems 49 (1997), S. 59-70 
    Details
    ISSN: 1573-0867
    Keywords: land use ; methane ; nitrogen fertilizer ; oxidation ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Aerobic soils are an important sink for methane (CH4) contributing up to 15% of annual global CH4 destruction. However, the sink strength is significantly affected by land management, nitrogen (N) fertilizers and acidity. We tested these effects on samples taken from the Broadbalk Continuous Wheat, Park Grass permanent grassland and Broadbalk and Geescroft Wilderness experiments at Rothamsted. The rates of uptake from the atmosphere of both enhanced (10 ppmv) and ambient (2 ppmv) concentrations of CH4 were measured in laboratory incubations of soil cores under controlled conditions. The most rapid rates of uptake were measured in soil from deciduous woodland at pH 7 (measured in water); acidic (pH 4) woodland soil showed no net CH4 oxidation. While disturbance of the cores used in the experiments did not affect the rate of CH4 uptake, extended (150 years) cultivation of land for arable crops reduced uptake rate by 85% compared to that in the soil under calcareous woodland. The long-term application of ammonium- (NH4) based fertilizer, but not nitrate- (NO3) based fertilizer, completely inhibited CH4 uptake, but the application for the same period of farmyard manure that contained more N than the fertilizer had no inhibitory effect. Although the effects of agricultural practice on the oxidation of CH4 in soil are significant, the differences in oxidation rates between land use types are even greater. The likely effects of forest clearance, agricultural intensification and anthropogenic emissions of CH4 over the last 2500 years have been estimated for the United Kingdom. The calculations indicate that 54% of the current CH4 uptake by UK soils is the result of increased CH4 mixing ratio. They also indicate that land use change has decreased the potential sink strength by 62% or 37 kt CH4 g-1. In countries with much larger land areas than the UK, such as China, aerobic soil is likely to be a more significant factor in calculating net fluxes of CH4. It is important that the impacts of different agricultural managements and land use systems are understood and quantified so that the best possible estimate of CH4 sinks is calculated for comparison with sources.
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    URL: http://dx.doi.org/10.1023/A:1009704226554
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    Effects of Interference and Oxidation on the UV/Visible Rejection Properties of Filters for Soft X-ray Detectors (1997)
    Springer
    Experimental astronomy 7 (1997), S. 51-63 
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    ISSN: 1572-9508
    Keywords: X-ray ; calibration ; filters ; interference ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report on UV/Visible transmission measurements of aluminum coated Lexan filters designed as UV blocking filters for soft x-ray detectors. Transmission of the filters in the 2300-8000 Å wavelength range is significantly higher than expected. It cannot be accounted for applying a simple slab model of the transmission and adopting material properties reported in the literature. We show that this is due to interference effects which are strongly dependent on the filter geometry, and to oxidation of exposed aluminum surfaces and/or chemical interaction with the plastic support. The results of this work have led to the redesign of the Advanced X-ray Astrophysics Facility High Resolution Camera UV blocking filters.
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    URL: http://dx.doi.org/10.1023/A:1007919005280
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    GMP-stimulation of the cyanide-insensitive mitochondrial respiration in heat-shocked conidia ofNeurospora crassa (1987)
    Springer
    Cellular and molecular life sciences 43 (1987), S. 439-440 
    Details
    ISSN: 1420-9071
    Keywords: Neurospora crassa ; conidia ; heat-shock ; mitochondria ; cyanide-insensitive respiration ; guanosine 5′-monophosphate (GMP)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In mitochondria of heat-shocked conidia ofNeurospora exogenous NADH and succinate were oxidized mainly via the alternative, hydroxamate-sensitive pathway (70%) and only 30% via the cytochromic, cyanide-sensitive pathway which was predominant in untreated conidia; the alternative oxidase pathway was markedly stimulated by guanosine 5′-monophosphate (GMP).
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    Anaerobic ammonia oxidation with nitrogen dioxide by Nitrosomonas eutropha (1997)
    Springer
    Archives of microbiology 167 (1997), S. 106-111 
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    ISSN: 1432-072X
    Keywords: Key wordsNitrosomonas ; Anaerobic ammonia ; oxidation ; Anaerobic cell growth ; Nitrogen dioxide ; Nitric oxide ; Nitrous oxide ; Dinitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrosomonas eutropha, an obligately lithoautotrophic bacterium, was able to nitrify and denitrify simultaneously under anoxic conditions when gaseous nitrogen dioxide (NO2) was supplemented to the atmosphere. In the presence of gaseous NO2, ammonia was oxidized, nitrite and nitric oxide (NO) were formed, and hydroxylamine occurred as an intermediate. Between 40 and 60% of the produced nitrite was denitrified to dinitrogen (N2). Nitrous oxide (N2O) was shown to be an intermediate of denitrification. Under an N2 atmosphere supplemented with 25 ppm NO2 and 300 ppm CO2, the amount of cell protein increased by 0.87 mg protein per mmol ammonia oxidized, and the cell number of N. eutropha increased by 5.8 × 109 cells per mmol ammonia oxidized. In addition, the ATP and NADH content increased by 4.3 μmol ATP (g protein)–1 and 6.3 μmol NADH (g protein)–1 and was about the same in both anaerobically and aerobically grown cells. Without NO2, the ATP content decreased by 0.7 μmol (g protein)–1, and the NADH content decreased by 1.2 μmol (g protein)–1. NO was shown to inhibit anaerobic ammonia oxidation.
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    Determination of kerogen type by using DSC and TG analysis (1997)
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    Journal of thermal analysis and calorimetry 49 (1997), S. 745-753 
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    ISSN: 1572-8943
    Keywords: DSC ; kerogen ; oxidation ; pyrolysis ; type determination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The rate of pyrolysis and oxidation of 8 different samples of oil shale kerogen concentrate (KC) were investigated using DSC analysis. Recently performed thermogravimetric studies (TG and DTG) with the same samples of KC indicated that the activation energy of the pyrolysis of specific KCs increases with increasing paraffinic structure in the KC. An opposite effect, i.e. a decrease of the activation energy with an increase of paraffinic structure was determined in the case of KC oxidation. In this study, using the standard ASTM E-698 method based on the determined temperature at which the maximum heat effect could be observed (exo in the case of oxidation and endo in the case of pyrolysis), an activation energy for the pyrolysis, as well as for the oxidation process was determined and also successfully correlated with the content of paraffinic structure of KC. Thus, the higher content of paraffinic structure in KCs indicates that higher values of the activation energy could be determined either in the case of pyrolysis or oxidation followed by DSC analysis.
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    Comparative studies on some analytical methods (1997)
    Springer
    Journal of thermal analysis and calorimetry 49 (1997), S. 857-862 
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    ISSN: 1572-8943
    Keywords: analytical methods ; kinetics ; powder milk ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This work present comparative results on powder milk storage quality, obtained from analytical methods. Protein content was determined conventional (Kjeldahl) and colorimetric with biuret reagent at 540 nm and integral quality by thermogravimetric and biological methods. A method was developed for the protein separation of powder milk. Powder milk was submitted to degradation processes at 45, 60 and 80°C for 20 days. The results indicated that protein content values were inconsistent if determinations by Kjeldahl and colorimetric methods and biological tests were compared. There is evidence of thermal decomposition of powder milk as detected by biological and thermogravimetric methods.
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    Using isothermal microcalorimetry for the prediction and testing of long-term properties of materials and products (1997)
    Springer
    Journal of thermal analysis and calorimetry 49 (1997), S. 1017-1023 
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    ISSN: 1572-8943
    Keywords: degradation ; microcalorimetry ; moisture ; oxidation ; permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The use of isothermal microcalorimetry (MC) as a sensitive monitor for slow reactions is demonstrated in a number of examples. In Example 1 the spontaneous decomposition of a nitrate ester propellant is studied and the absolute degradation rate estimated. Example 2 illustrates how MC can be used for comparing the rate of oxidative ageing at different O2 concentrations. Synergetic effects between oxygen and moisture in accelerated ageing of nitrile rubber are evaluated from a so-called 4-point test in Example 3. The last example shows a simple MC technique for rapid determination of moisture permeability through a polymeric sealant.
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    Thermal properties and reactivity determination of micro- and submicrometer nickel powders (1997)
    Springer
    Journal of thermal analysis and calorimetry 48 (1997), S. 657-664 
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    ISSN: 1572-8943
    Keywords: nickel powders ; oxidation ; thermal analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Monodispersed fine metal nickel powders of uniform shape and high purity are increasingly required for specific uses in many technological areas, especially in the preparation of electronic materials such as the manufacture of conductive inks and pastes and the formation of catalysts. Metallic nickel powders were prepared in ethylene glycol by the reduction of a nickel solution. Hydrazine was used as a reducing agent. Metal powders were characterized by chemical analysis, scanning electron microscopy (SEM), thermogravimetry (TG), derivative thermogravimetry (DTG) and differential scanning calorimetry (DSC). Particle size distributions were determined using laser light scattering. The reactivity and purity of these fine nickel powders were tested by repeated oxidation and reduction of nickel powders in oxidative and reductive atmospheres.
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    Thermogravimetric studies of the synthesis of cas from gypsum, CaSo4·2H2O and phosphogypsum (1997)
    Springer
    Journal of thermal analysis and calorimetry 49 (1997), S. 1501-1507 
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    ISSN: 1572-8943
    Keywords: calcium sulphide ; gypsum ; oxidation ; phosphogypsum ; reduction ; stability ; thermogravimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Using a heating rate of 2°C min−1, CaS reacts with oxygen in air from 700°C to form CaSO4, with a complete conversion at 1100°C. Synthesis of CaS from the reaction between CaSO4 containing compounds and carbon compounds in air would not be possible, as the carbon reacts from 600°C with oxygen in the air to give CO2. Heating stoichiometric amounts of carbon and pure CaSO4, synthetic gypsum or phosphogypsum in a nitrogen atmosphere, results in the formation of CaS from 850°C. Using a heating rate of 10°C min−1, the formation of CaS is completed at 1080°C. Addition of 5% Fe2O3 as a catalyst lowers the starting temperature of the reaction to 750°C. Activation energy values at different fraction reaction values (α) differ between 340 and 400 kJ mol−1. The relationship between the activation energy values and conversion (α) indicates that the reaction proceeds via multiple steps.
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    Low/high temperature relationships in dinitramide salts by DEA/DSC and study of oxidation of aluminum powders by DSC/TG (1997)
    Springer
    Journal of thermal analysis and calorimetry 49 (1997), S. 1161-1170 
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    ISSN: 1572-8943
    Keywords: basicity ; dinitramides ; kinetics ; oxidation ; tanδ ; transition temperatures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The dinitramide salts of ammonia (ADN), hexamethylenetetramine (HDN), potassium (KDN), and sodium (NaDN) showed a linear relationship between the DSC rate of decomposition at the peak maximum and the DEA tanδ value at the low temperature transition peak. As the cation basicity increased in the series ADN〈HDN〈KDN〈NaDN, there was an increase in the low temperature transition peak, the energy barrier for relaxation, and the decomposition peak temperature, and a decrease in the tanδ value at the low temperature transition peak, specific heat capacity, and the rate and enthalpy of decomposition. The more basic salts were more thermally stable (i.e., higher decomposition temperature) and less energetic (i.e., lower enthalpy of decomposition). The more internal free volume (disorder) present in these salts, the higher the rates of relaxation and decomposition. Five aluminum powders of different surface areas were analyzed by DSC in platinum sample pans, and it was found that the enthalpy and rate of oxidation increased as the particle size of Al decreased while the enthalpy of the Al melt decreased. TG showed a two-step weight gain in the oxidation of Al with plateaus in the 650 and 1130°C regions and the percent weight gain increased as the particle size of Al decreased. Variable DSC and TG heating rate studies showed that the activation energies for the first step in the oxidation process increased as the particle size of Al increased.
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    URL: http://dx.doi.org/10.1007/BF01983671
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    Measurement by LASER-Generated Ultrasound of Four Stiffness Coefficients of an Anisotropic Material at Elevated Temperatures (1997)
    Springer
    Journal of nondestructive evaluation 16 (1997), S. 91-100 
    Details
    ISSN: 1573-4862
    Keywords: LASER ultrasound ; anisotropic material ; group velocity ; stiffness coefficients ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Ultrasonic waves are generated through a composite material by means of a noncontact technique. It uses a Nd:Yag LASER for the generation and an interferometric probe for the detection of acoustic waveforms. From a suitable set of experimental data, an inversion scheme is used for the recovering of four stiffness coefficients. They characterize the elasticity in a principal plane of symmetry of the material which exhibits an orthorhombic symmetry. The measurements are performed at various temperatures, elevated by steps up to 300°C for two specimen. The sensitivity of the method appears convenient to measure the temperature induced stiffness changes. The anisotropic degradation of the material properties are then pointed out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022620501899
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    Reaction of water vapor and oxygen with liquid uranium (1987)
    Springer
    Oxidation of metals 28 (1987), S. 195-211 
    Details
    ISSN: 1573-4889
    Keywords: Uranium ; corrosion ; oxidation ; liquid metal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The reactions of water vapor and oxygen with liquid uranium were studied by modulated molecular-beam mass spectrometric methods. Equivalent pressures of the reactant fluxes on the surface ranged from 6×10 −6 to 2×10−4 torr. Temperatures up to 1570 K were investigated. The metal surface was kept clean during reaction by mechanical removal of the oxide formed with a tungsten needle. For the clean liquid uranium surface, a water reaction probability of ∼0.4 was deduced both from measurement of the reaction-product hydrogen signal and by the temperature dependence of the scattered reactant signal. Based solely on the latter measure, a reaction probability of 0.6 was estimated for oxygen. The reaction probabilities on the clean surface were temperatureindependent. They decreased as the coverage of the surface by islands of oxide increased and, for water, appeared to approach a value of 0.08 for a surface completely covered with an oxide estimated to be 500 Å thick. Bombardment of the surface during reaction with argon ions produced an increase in the reactivity on solid uranium but had a negligible effect on the reaction probability for the liquid.
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    URL: http://dx.doi.org/10.1007/BF00656707
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    Evolution of grain structure in nickel oxide scales (1987)
    Springer
    Oxidation of metals 28 (1987), S. 353-389 
    Details
    ISSN: 1573-4889
    Keywords: Grain growth ; nickel oxide ; high temperature ; oxidation ; nickel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In systems such as the oxidation of nickel, in which grain-boundary diffusion in the oxide can control the rate of oxidation, understanding of the factors governing the grain structure is of importance. High-purity mechanically polished polycrystalline nickel was oxidized at 700°C, 800°C, and 1000°C for times up to 20 hr in 1 atm O2. The scale microstructures were examined by parallel and transverse cross section transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Texture coefficients were found by X-ray diffraction (XRD). Each grain in the transverse section grain boundary networks was systematically analyzed for width parallel to the Ni-NiO interface and perpendicular length, for boundary radius of curvature and for number of sides. The variation of these parameters with depth in the scale was examined. In particular, grains were increasingly columnar (i.e., with ratio of grain length to width 〉1) at higher temperatures and longer times. Columnar grain boundaries tended to be fairly static; the columnar grain width was less than the rate controlling grain size predicted from the oxidation rate. The mean boundary curvature per grain provided a guide to the tendency for grain growth, except in the region of the Ni-NiO interface, where the boundaries were thought to be pinned.
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    URL: http://dx.doi.org/10.1007/BF00666728
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    Oxidation behavior of several chromia-forming commercial nickel-base superalloys (1997)
    Springer
    Oxidation of metals 47 (1997), S. 381-410 
    Details
    ISSN: 1573-4889
    Keywords: Ni-Base superalloys ; Astroloy ; Waspaloy ; Udimet 720 ; oxidation ; chromia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Several commercially available Ni-base superalloys were exposed isothermally in air at temperatures between 750° and 1000°C and also under cyclic conditions at 1000°C. The kinetics of oxidation were determined and the scales were analyzed by electron microscopy and X-ray diffraction. Thin adherent chromia-rich scales formed on the alloys at 750°C after 1000 hr. Although Waspaloy showed the lowest weight gain in this test, it also showed the deepest internal corrosion due to oxidation of the grain-boundary carbides. At temperatures up to 1000°C the external scales were also chromia-rich but there was greater internal corrosion. Titanium in the alloys oxidized, diffusing through the chromia scale to form faceted rutile (TiO2) grains at the surface as well as forming TiO2 and TiN internally. The amount of rutile at the oxide surface increased with temperature and alloy Ti concentration. Alumina formed as discrete internal oxides below the chromia scale, although Astroloy when oxidized isothermally at 1000°C developed a semicontinuous internal layer of alumina due to its higher Al content. Under cyclic conditions Astroloy formed a thicker, less-protective scale of transition oxides probably due to its lower Cr content.
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    Oxidation behavior of an Fe-38Ni-13Co-4.7Nb-1.5Ti-0.4Si superalloy at high temperature in Ar-H2O atmospheres (1997)
    Springer
    Oxidation of metals 47 (1997), S. 411-426 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; Incoloy 909 ; superalloy ; scale ; high temperature ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of an Fe-38Ni-13Co-4.7Nb-1.5Ti-0.4Si superalloy (Incoloy 909 type alloy), was investigated at temperatures between 1000 K and 1400 K in Ar-(1, 10%)H20 atmosphere using metallographic, electron probe microanalysis, and X-ray diffraction techniques. The oxide scales consist of an external scale and an internal scale which has an intergranular scale (above 1200 K) and an intergranular scale. The oxide phases in each scale are identified asα-Fe2,O3 (below 1200 K) or FeO (above 1300 K) and CoO · Fe2O3 and FeO · Nb2O5, respectively. The morphologies, the oxide phases and the oxidation rates do not depend on the partial pressure of H2O in the range between one and ten percent in Ar gas. The rate constants for the intergranular-scale formation in this alloy are about one-tenth as large as those in Fe-36%Ni alloy reported previously. At all the temperatures the scales grow according to a parabolic rate law and the apparent activation energies for the processes are estimated.
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    URL: http://dx.doi.org/10.1007/BF02134784
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  • 39
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    Water-vapor-effect on the oxidation of Fe-21.5 wt.%Cr-5.6 wt.%Al at 1000°C (1997)
    Springer
    Oxidation of metals 47 (1997), S. 445-464 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; Fe-Cr-Al alloy ; water vapor ; ESCA ; RHEED
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Fe-21.5 wt. %Cr-5.6 wt. %Al oxidation, at 1000°C, in dry or wet oxygen shows that steam has an influence on the oxide-scale growth mechanism. Steam modifies the kinetics of early-stage oxidation. In dry oxygen, an initial fast linear regime is observed during one hour. Under wet conditions, weight-gain curves follow the same parabolic regime over the entire oxidation test. The scale structure strongly depends on the presence of steam in the gaseous environment. With dry oxygen, the scale is composed mainly ofα-Al2O3 after the initial formation ofγ-Al2O3 identified by ESCA and RHEED. The kinetics transient stage corresponds to the necessary time for the internal part of the initialγ-Al2O3 scale to transform into a continuousα-Al2O3 diffusion barrier. Under wet oxygen conditions, transient oxides are identified as (Mg, Fe) (Cr, Al)2O4, MgAl2O4 (orthorhombic), Al2O3 (hexagonal), these oxides transform into MgAl2O4 (cubic), Cr3O4, Fe2O3,α-Al2O3, with time. When water vapor does not change drastically oxidation kinetics, the induced presence of iron and chromium in the oxide scale could be responsible for weakening the protectiveness of alumina scales.
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    URL: http://dx.doi.org/10.1007/BF02134786
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    The transient state in the oxidation of binary alloys forming the most-stable oxide: A numerical solution (1997)
    Springer
    Oxidation of metals 47 (1997), S. 507-524 
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    ISSN: 1573-4889
    Keywords: alloys ; high temperature ; oxidation ; transient state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The initial transient high-temperature oxidation stage for binary alloys forming the most-stable oxide has been examined by means of a numerical procedure based on the finite-difference method. At variance with previous models, the present treatment takes into account the effect of the rate of the reaction at the scale/gas interface over the corrosion kinetics. The calculations concerning the transient stage are developed either using the general parabolic rate law to represent the overall scaling kinetics or using the rate law of the reaction at the scale/gas interface as a boundary condition without imposing any particular rate law to the overall process. A correct analysis of the oxidation behavior of binary alloys during the transient stage must take into account the kinetics effect of the rate of the surface reaction. The concentration of the most-reactive element at the alloy/scale interface changes regularly with time, decreasing gradually from the initial bulk value to its final steady-state value. The present results are in good agreement with those obtained by means of an approximate analytical model developed previously.
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    URL: http://dx.doi.org/10.1007/BF02134789
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    An approximate treatment of the transient state in the oxidation of binary alloys forming the most-stable oxide. Part II: Single-phase alloys in systems with a solubility gap (1997)
    Springer
    Oxidation of metals 47 (1997), S. 525-550 
    Details
    ISSN: 1573-4889
    Keywords: high temperatures ; oxidation ; transient state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The transient state in the oxidation of solid solutions of a most-noble componentA in a most-reactive componentB (beta phase) for binaryA-B alloys presenting a limited reciprocal solubility of the two metals has been examined assuming that theirB content is sufficient for the exclusive growth of externalBO scales. Above a criticalB content of the alloy theBO scales may grow directly on the surface of the beta phase, while below this limit they can only form over a layer ofB-depleted solid solution ofB inA (alpha phase), which appears after a critical time. An approximate analytical expression for the profile of concentration ofB in the alloy has been adopted to calculate the flux ofB in the metal. Moreover, the effect of the reaction between the gas and the external oxide surface has been taken into account using a procedure developed by Wagner for the oxidation of pure metals. The corrosion kinetics as well as all the parameters involved, such as the concentration ofB at the alloy-scale interface, have been calculated as functions of the corrosion time. The results show that, as time proceeds, the instantaneous parabolic rate constant increases and the concentration ofB at the alloy-scale interface decreases, both tending gradually to their corresponding steady-state values. It is also predicted that if the rate of transformation of the beta phase in the alpha phase after the alloy reaches the composition of equilibrium at the interface with the oxide is lower than the corresponding rate of displacement of the alloy surface due to scale growth, the corrosion of beta phase alloys may eventually lead to the formation of two phase mixtures of alpha phase andBO which are expected to grow at much larger rates than in the presence of a uniform continuous alpha layer.
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    URL: http://dx.doi.org/10.1007/BF02134790
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    Evolution of oxides on Ni-base ODS superalloys (1997)
    Springer
    Oxidation of metals 48 (1997), S. 1-39 
    Details
    ISSN: 1573-4889
    Keywords: Ni-base ODS superalloys ; oxidation ; initial stages of oxidation ; alumina ; chromia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Mechanically-alloyed Ni-base ODS superalloys currently receive attention for application in future gas turbines because they exhibit outstanding mechanical properties at high temperatures. They also protect themselves against oxidation by forming chromia and/or alumina scales. However, little attention has been given so far to the initial stages of oxidation of Ni-base ODS superalloys, containing Cr as well as Al in considerable amounts. In the current work, oxidation at 1150°C was studied for different holding times up to 200 hr for the commercial materials MA6000 and PM3030 which contain. Al in increasing amounts. MA 754, a chromia former, was investigated as a reference. It was shown that for the potential alumina formers MA6000 and PM3030 the continuity and therefore protectiveness of the secondary Al2O3 at later stages is indeed determined by the initial stages of oxidation.
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    URL: http://dx.doi.org/10.1007/BF01675260
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    Decarburization and internal oxidation in a commercial-grade nickel (1997)
    Springer
    Oxidation of metals 48 (1997), S. 129-141 
    Details
    ISSN: 1573-4889
    Keywords: decarburization ; nickel ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A commercial-grade nickel containing small amounts of carbon, manganese, and silicon was exposed to air for periods up to 288 hr at 1050°C to study the effect of oxidation on the formation of oxides of these impurity elements. Exposure of nickel to air led to decarburization. The maximum amount of decarburization occurred during the initial period of air exposure and the loss in carbon was more in the metal with a smaller section size. Decarburization in the metal produced voids in the oxide scale due to the formation of CO2 gas. It has been shown further that CO and/or CO2 gas bubbles, which form in high purity nickel on grain boundaries during exposure to air at elevated temperatures, cannot exist in commercial-grade nickel where manganese is present as an impurity. Instead, oxides of manganese form in the grain boundaries as well as in the matrix. This is because manganese oxide is more stable than CO or CO2 gas.
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    URL: http://dx.doi.org/10.1007/BF01675265
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    On the oxidation ofα-Fe andε-Fe2N1−z : I. Oxidation kinetics and microstructural evolution of the oxide and nitride layers (1997)
    Springer
    Oxidation of metals 48 (1997), S. 87-109 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; kinetics ; iron ; iron-nitride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of α-Fe and ɛ-Fe2N1−z at 573 K and 673 K in O2 at 1 atm was investigated by thermogravimetrical analysis, X-ray diffraction, light-optical microscopy, scanning electron microscopy and electron probe X-ray microanalysis. Upon oxidation at 573 K and 673 K, on α-Fe initially α-Fe2O3 develops, whereas on ɛ-Fe2N1−z initially Fe3O4 develops. In an early stage of oxidation the oxidation rate of ɛ-Fe2N1−z appears to be much larger than of α-Fe. This can be attributed largely to an effective surface area available for oxygen uptake, which is much larger for ɛ-Fe2N1−z than for α-Fe due to the porous structure of ɛ-Fe2N1−z as prepared by gaseous nitriding of iron. The development of a magnetite layer in-between the hematite layer and the α-Fe substrate, at a later stage of oxidation, enhances layer-growth kinetics. After 100 min oxidation at 673 K the (parabolic) oxidation rates for α-Fe and ɛ-Fe2N1−z become about equal, indicating that on both substrates the oxide growth is controlled by the same rate limiting step which is attributed to short-circuit diffusion of iron cations. Oxidizing ɛ-Fe2N1−z increases the nitrogen concentration in the remaining ɛ-iron nitride, because the outward flux of iron cations, necessary for oxide growth, leads to an accumulation of nitrogen atoms left behind.
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    URL: http://dx.doi.org/10.1007/BF01675263
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    Effect of niobium additions on CO2-enhanced oxidation of titanium-aluminum intermetallic alloys (1997)
    Springer
    Oxidation of metals 48 (1997), S. 201-214 
    Details
    ISSN: 1573-4889
    Keywords: titanium-aluminum alloys ; niobium ; intermetallics ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In a recent study, CO2 has been reported to enhance the oxidation rate of binary titanium-aluminum alloys. The detrimental effect of CO2 was not, however, observed in a ternary alloy containing niobium. In this paper, possible explanations for these observations are examined. First, results from the literature regarding the effects of niobium in improving the resistance of titanium-aluminum alloys are briefly reviewed. Second, a thermodynamic analysis which offers a possible explanation for the beneficial effect of niobium in eliminating the CO2-enhanced oxidation of titanium-aluminum alloys is presented.
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    URL: http://dx.doi.org/10.1007/BF01670499
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    The effect of nanocrystallization on the selective oxidation and adhesion of Al2O3 scales (1997)
    Springer
    Oxidation of metals 48 (1997), S. 215-224 
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    ISSN: 1573-4889
    Keywords: nanocrystallization ; oxidation ; mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Many mechanisms for the effect of reactive elements on the selective oxidation and scale adhesion of alloys have been proposed. However, nanocrystallization (or microcrystallization) has recently been found to have almost the same effect as that of reactive elements. This note reviews the effect of nanocrystallization on the selective oxidation and adhesion of Al2O3 scale with particular reference to the author's own results.
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  • 47
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    High-temperature oxidation of pure titanium in CO2 and Ar-10%CO2 atmospheres (1997)
    Springer
    Oxidation of metals 48 (1997), S. 289-302 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; titanium ; rutile ; scale ; high temperature ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation behavior of pure titanium has been investigated in the temperature range of 1000 K to 1300 K in CO2 or Ar-10%CO2. Optical microscopy, electron probe microanalyses, and X-ray measurements on the oxide scales formed during oxidation indicate that their structures are nearly independent of temperature and the corrosion atmosphere. The scales consisted of two layers, an external one and an internal one, having a rutile (TiO2) structure. The parabolic rate law was confirmed for growth of the external scale and the permeation depth of oxygen in titanium with apparent activation energies of 266 and 226 kJ/mol, respectively. The rate-determining diffusion species in the oxidation processes are discussed.
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    Phase analysis by variable-incidence X-ray diffraction: Application to zirconium oxidation (1997)
    Springer
    Oxidation of metals 48 (1997), S. 329-345 
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    ISSN: 1573-4889
    Keywords: zirconium ; X-ray diffraction ; oxidation ; phase analysis ; texture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of zirconium at high temperature (T〉 400°C) leads to reaction products of two allotropic oxide (ZrO2 monoclinic and ZrO2 tetragonal). The distribution and proportion of these two phases were studied as a function of time and space by X-ray diffraction techniques. Quantitative analyses are possible after some corrections, and we demonstrate the presence of a phase gradient in the oxide scale. The interest of this nondestructive method is then discussed.
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    The air oxidation of two-phase Cu-Cr alloys at 700–900°C (1997)
    Springer
    Oxidation of metals 48 (1997), S. 357-380 
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    ISSN: 1573-4889
    Keywords: chromium ; copper ; binary alloys ; two-phase alloys ; oxidation ; high temperatures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation in air of three two phase Cu-Cr alloys with nominal Cr contents of 25, 50, and 75 wt. % was studied at 700–900°C. The alloys corroded nearly parabolically, except at 900°C, when the corrosion rates decreased with time more rapidly than predicted by the parabolic rate law. The corrosion rate decreased for higher Cr contents in the alloy under constant temperature and generally increased with temperature for the same alloy composition. The scales were complex and consisted in most cases of an outermost copper oxide layer free from chromium and an inner layer composed of a matrix of copper oxide or of the double oxide Cu2Cr2O4, often containing particles of chromium metal surrounded by chromia and then by the double oxide. Metallic copper was also frequently mixed with chromia. Cr-rich regions tended to form continuous chromia layers at the base of the scale, especially at the highest temperature. No chromium depletion was observed in the alloy.
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    URL: http://dx.doi.org/10.1007/BF02153456
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    Influence of ceria coatings on growth stresses developed in wüstite scales formed on pure iron at 800°C (1997)
    Springer
    Oxidation of metals 48 (1997), S. 417-438 
    Details
    ISSN: 1573-4889
    Keywords: iron ; oxidation ; CeO2 coating ; in situ ; growth stress ; residual stress ; texture ; X ray diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In situ XRD stress determinations have been performed during oxidation of pure iron (p(O2=2 × 10−3 Pa,T=800°C)). The compressive stress, initially present in the substrate due to surface preparation, is completely released at 400°C. Under the test conditions, the in situ compressive-stress level determined in the FeO scale during oxidation is not strongly dependent upon the presence of a ceria coating. On blank and coated specimens, the compressive stress varies from −400 ± 80 MPa to −150 ± 100 MPa during 30 hr oxidation. The decrease is quicker at the beginning of the test performed on blank specimens. Epitaxial relationships between the wüstite scale and iron (under low-pressure starting conditions) caused thein situ compressive stress in the oxide scale to be two times greater compared to the usual test conditions. This indicates that epitaxial relationships can be a source of stress in an oxide scale that ceria coatings may lower compressive stresses.
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    Chloridation-oxidation of Fe-Cr and Ni-Cr alloys at 800°C (1997)
    Springer
    Oxidation of metals 48 (1997), S. 527-551 
    Details
    ISSN: 1573-4889
    Keywords: chloridation ; oxidation ; Fe-Cr alloys ; Ni-Cr alloys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The chloridation-oxidation behavior of Fe-Cr (0–25 wt. %Cr) and Ni-Cr (0–20 wt.%Cr) alloys was studied at 800°C in three different H2-HCl-H2O(ν) environments. In a low-HCI and low-H2O(ν) environment, where Cr2O3 is thermodynamically stable, the corrosion resistance of the Fe-Cr alloys increased with increasing Cr content in the alloys. In a high-HCl and high-H2O(ν) environment, where FeCr2O4 is stable and CrCl2 is metastable, the corrosion resistance of the Fe-Cr alloys depended similarly on the Cr content. Low-Cr-Fe-Cr alloys exhibited large weight losses, while Fe-Cr alloys with higher than 19 wt. %Cr showed good corrosion resistance. In an environment of high-HCl in the absence of H2O(ν), the evaporative corrosion rate was fast and limited by gas phase diffusion, and independent of the Cr content in the Fe-Cr alloys. Ni and Ni-Cr alloys generally showed good corrosion resistance in the environments of high H2O(ν) because of the low NiCl2 vapor pressure and formation of a protective Cr2O3 scale. However, in the environment of high HCl in the absence of H2O(ν), selective formation and evaporation of CrCl2 occur, which results in Cr depletion and networks of voids for even a high-Cr Ni-Cr alloy.
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    Chloridation-oxidation of nine commercial high-temperature alloys at 800°C (1997)
    Springer
    Oxidation of metals 48 (1997), S. 553-596 
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    ISSN: 1573-4889
    Keywords: chloridation ; oxidation ; HCl ; high-temperature alloys ; high-temperature corrosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Chloridation-oxidation studies of nine commercial high-temperature alloys were carried out at 800°C in three different H2-HCl-H2O(ν) environments: (A) both low HCl and H2O(ν) partial pressures, where either Cr2O3 or FeCr2O4 is stable, (B) both high HCl and H2O(ν) partial pressures, where FeCrO4 is stable and CrCl2 is metastable, and (C) high HCl partial pressure in the absence of H2O(ν), where either CrCl2 or Cr2O3 is stable. Although alloy 600 has the lowest Cr content of these nine alloys, it showed excellent corrosion resistance in all three environments because of its high Ni content. Alloy 304, with the lowest Ni content of the nine alloys, exhibited poor corrosion resistance in the environment C, fair resistance in the environment B and good resistance in the environment A. Alloy 800 showed very good resistance in Environment A, and fair corrosion resistance in Environment B; however, it suffered linear weight-loss kinetics when exposed to Environment C The alloys 617, 214, HR-160, X, 230 and 86 have good corrosion resistance in Environments A and B because of their relatively high contents of oxide-scale-forming elements Cr and/or Al. In Environment C, chlorine dramatically decreased the adhesion of the scale on the surface, and aluminum in alloys 617 and 214 hardly showed its usual beneficial effect in combating corrosion, nor does silicon in alloy HR-160. Different corrosion mechanisms are proposed for the alloys in the different environments.
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    URL: http://dx.doi.org/10.1007/BF02153465
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    Expression of oxidative phosphorylation genes in muscle cell cultures from patients with mitochondrial myopathies (1997)
    Springer
    Molecular and cellular biochemistry 168 (1997), S. 73-85 
    Details
    ISSN: 1573-4919
    Keywords: muscular diseases ; mitochondria ; MTDNA ; ATP synthase ; human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The expression of several mitochondrial and nuclear genes involved in ATP production was examined in cells cultured from muscle biopsies of patients harboring mitochondrial pathologies. The transcript patterns in muscle cells from the patients affected by carnitine palmitoyl transferase II or 2-ketoglutarate dehydrogenase deficiencies were almost similar to control patterns. In the opposite, patterns were strikingly abnormal in all the other cell cultures from patients with defects in enzymatic complexes involved in oxidative phosphorylation: mitochondrial complex II and III deficiencies, two MELAS syndromes (myopathy, encephalopathy, lactic acidosis and stroke like episodes), a case of Kearns-Sayre syndrome and a case of chronic progressive external ophthalmoplegia. In cultured muscle cells from patients with mtDNA mutations, the percentage of mutated mtDNA was low as compared with those determined in the corresponding skeletal muscle biopsy. Moreover, the complex II defect resulting of a nuclear mutation was not expressed in the cell cultures. Thus, an undetermined transcriptional event, transmitted from muscle biopsies to cultured muscle cells, should be involved to account for such abnormal transcript patterns.
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    URL: http://dx.doi.org/10.1023/A:1006830807107
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    Lipid peroxidation induced by a novel porphyrin plus light in isolated mitochondria: Possible implications in photodynamic therapy (1997)
    Springer
    Molecular and cellular biochemistry 166 (1997), S. 25-33 
    Details
    ISSN: 1573-4919
    Keywords: porphyrin derivative ; mitochondria ; ascites ; singlet oxygen ; photosensitization ; lipid peroxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract With a view to locate porphyrins for use in photodynamic therapy (PDT), the new modality of cancer treatment we have evaluated the ability of a novel water soluble porphyrin meso-tetrakis[4-(carboxymethyleneoxy)phenyl]porphyrin (T4CPP) to induce damage to mitochondria during photosensitization. T4CPP, when exposed to visible light, induced lipid peroxidation in rat liver mitochondria as assessed by the formation of thiobarbituric acid reactive substances (TBARS), conjugated dienes (CD) and lipid hydroperoxides (LOOH). The effect on mitochondrial function was assessed by estimating the activity of succinate dehydrogenase (SDH). The peroxidation induced was observed to be time- and concentration- dependent. Analysis of product formation and selective inhibition by scavengers of reactive oxygen species showed that the oxidative damage observed was mainly due to singlet oxygen (1O2) and partly due to other reactive species. T4CPP plus light also caused significant lipid peroxidation in Sarcoma 180 ascites tumour mitochondria. Our studies indicate that T4CPP has the potential to photoinduce damage in hepatic and ascites mitochondria, a crucial site of damage in PDT. (Mol Cell Biochem 166: 25-33, 1997)
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    URL: http://dx.doi.org/10.1023/A:1006840714583
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    Mitochondrial involvement in the ageing process. Facts and controversies (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 325-328 
    Details
    ISSN: 1573-4919
    Keywords: ageing ; theory ; mitochondria ; respiratory chain ; mitochondrial DNA mutations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Mitochondria are believed to be involved in human ageing. Whilst it is clear that various mitochondrial DNA mutations do accumulate in human tissues with age, whether or not they interfere with respiratory chain function is uncertain. We question the results of previous studies which have measured respiratory chain function in human skeletal muscle with age. Whilst cytochrome c oxidase deficient fibres are a real finding in skeletal muscle, the contribution of mitochondrial DNA mutations to human ageing is still controversial. Our results show for mitochondria to be involved in ageing then it must be through a more subtle mechanism than a global decline in respiratory chain function. (Mol Cell Biochem 174: 325–328, 1997)
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    URL: http://dx.doi.org/10.1023/A:1006847319162
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    Distribution and characterization of high temperature air corrosion products on iron-chromium alloys by Raman microscopy (1987)
    Springer
    Oxidation of metals 27 (1987), S. 57-72 
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    ISSN: 1573-4889
    Keywords: Raman microscopy ; Fe-Cr alloys ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Raman microscopy has been used to study the nature and distribution of corrosion products formed on iron and iron-chromium alloys in air at high temperatures. Fe and Fe-Cr alloys containing 2, 5, 14, and 18% Cr were oxidized at 400, 600, and 850°C for 2 hr, in addition samples of each alloy were oxidized for 24 hr at 400°C to obtain thicker scales at this temperature. The corroded samples showed varying distributions of the oxides Fe2O3, Fe3O4, Cr2O3, and FeCr2O4. Fe2O3 and Fe3O4 were formed exclusively on the pure iron and the 2 and 5% chromium alloys at all temperatures and on the 14% chromium alloy at 400°C. The 14 and 18% Cr alloys formed scales containing Cr2O3 and FeCr2O4 at the higher temperatures (600 and 850°C). Examples of small regions of Fe2O3 being formed within Cr2O3-FeCr2O4 scales are suggested as possible indications of breakaway corrosion initiation sites.
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    URL: http://dx.doi.org/10.1007/BF00656729
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    High temperature oxidation of silicon carbide based materials (1987)
    Springer
    Oxidation of metals 27 (1987), S. 83-93 
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    ISSN: 1573-4889
    Keywords: silicon carbide ; oxidation ; constructional ceramics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The process of high temperature oxidation of two silicon carbide based materials differing by methods of their production and properties has been studied up to 1500°C in air. The oxidation was performed under the isothermal conditions and at the programmed heat rate of 10° per minute. It was found that the oxidation resistance of the material was the function of the presence of extrinsic metals having close affinity for oxygen. It was also found that under heating up to 1500°C in air phase transitions occurred in the SiC surface layer.
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    URL: http://dx.doi.org/10.1007/BF00656732
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    On the reasons for the effects of dispersions of stable oxides and additions of reactive elements on the adhesion and growth-mechanisms of chromia and alumina scales-the “sulfur effect” (1987)
    Springer
    Oxidation of metals 27 (1987), S. 75-81 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; adhesion ; growth-mechanisms ; impurities ; sulfur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The “sulfur effect” theory proposes that elements such as sulfur segregate to the scale-metal interface, where they have a deleterious effect on scale-metal adhesion, and that reactive elements and dispersions of their oxides are beneficial because they prevent this segregation. Evidence in favor of this theory has been obtained by showing that the adhesion of the scale formed on chromium in 0.1 atm. oxygen at 950°C. is greatly improved if the chromium is annealed beforehand in hydrogen instead of in vacuo. It is shown that the theory can explain not only all the experimental observations regarding the beneficial effects of reactive elements and their oxides on scale-metal adhesion, but also their effects on scale growth-mechanisms.
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    URL: http://dx.doi.org/10.1007/BF00656731
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    The role of aluminum and titanium on the oxidation process of a nickel-base superalloy in steam at 800°C (1987)
    Springer
    Oxidation of metals 27 (1987), S. 21-36 
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    ISSN: 1573-4889
    Keywords: oxidation ; steam ; Ni-base superalloy ; Al oxides ; Ti oxides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The role of aluminum and titanium on the oxidation process of a nickel-base superalloy containing 18.89%Cr, 2.13%Al, and 2.41%Ti was investigated in steam at 800°C. A Cr2O3-rich scale was formed on the alloy surface. Aluminum formed only internal oxides below the Cr2O3-rich scale. On the other hand, titanium formed not only internal oxides but also oxides in the scale and the granular particles of TiO2 outside the scale. Agglomeration of the TiO2 particles also occurred. The oxidation behavior of aluminum and titanium was discussed from thermodynamic and kinetics aspects.
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    URL: http://dx.doi.org/10.1007/BF00656727
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    Laser surface treatment and its influence on the development of healing Cr2O3 scales on nickel-chromium alloys (1987)
    Springer
    Oxidation of metals 27 (1987), S. 37-55 
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    ISSN: 1573-4889
    Keywords: laser treatment ; chromia scales ; oxidation ; nickel-chromium alloys ; laser glazing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The influence of laser surface treatment on the isothermal oxidation of Ni-10%Cr and Ni-15%Cr at 1025°C in oxygen at 1 atm pressure has been studied. Particular emphasis has been placed on the progressive establishment of a Cr2O3 healing layer, which is facilitated by rapid-diffusion paths for chromium to the surface from the bulk alloy. For nonlaser treated alloys, such paths are alloy grain boundaries. A partial Cr2O3 layer forms initially in localized sites at, and immediately adjacent to, these boundaries and progresses into the alloy grains in a stepwise manner following lateral diffusion of chromium from the grain boundaries, thereby developing a contoured configuration. For Ni-15%Cr, there is sufficient chromium in the bulk alloy grains to sustain the eventual development of a self-healing layer parallel to the surface. For Ni-10%Cr, this is not the case and complete development of the healing layer results entirely from the stepwise progression from the grain boundaries. Establishment of the healing layer on laser-glazed surfaces is facilitated by additional rapid-diffusion paths, particularly retained alloy grain boundaries, retained alloy twins, a laser-induced microstructure and solidification artifacts (such as ripples). The relative importance of these features is discussed in relation to the oxidation behavior.
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    URL: http://dx.doi.org/10.1007/BF00656728
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    Acoustic emission technique: An alternative method to study the brittle oxide formed on copper (1987)
    Springer
    Oxidation of metals 27 (1987), S. 95-102 
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    ISSN: 1573-4889
    Keywords: oxidation ; acoustic emission technqiue ; copper
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The acoustic emission technique has been utilized as an alternative technique to thermogravimetry to study the anomalous behavior of copper metal oxidation at 500°C The present work demonstrates an excellent example of the application of this technique in detecting cracks in growing oxide films.
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    URL: http://dx.doi.org/10.1007/BF00656733
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    Transcription of mitochondrial and mitochondria-related nuclear genes in rabbit bladder following partial outlet obstruction (1997)
    Springer
    Molecular and cellular biochemistry 173 (1997), S. 1-8 
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    ISSN: 1573-4919
    Keywords: outlet obstruction ; bladder ; mitochondria ; transcription ; RNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Using the rabbit model, we showed that partial outlet obstruction of theurinary bladder causes significant changes in the status and expression ofthe mitochondrial (mt) genetic system in bladder smooth muscle immediatelyafter obstruction is initiated. Here we investigate quantitatively theseverity of the mt genetic response to partial outlet obstruction in bothshort- and long-term obstructed rabbits. Based on previous functionalstudies, bladders with mass 〈 6 fold greater than control were consideredcompensated; bladders with mass 〉 6 fold that of control were considereddecompensated. Analyses of DNA from compensated rabbit bladders showed thatrelative mt genome copy number decreased to 30% of control values.Transcript analyses for these samples showed that mt RNA levels increased 3fold to compensate for lower template copy number. Analysis of decompensatedbladders demonstrated that mt genome copy number increased to approximately90% of control levels; mt transcripts progressively decreased inthese samples by as much as 30 fold. In contrast, transcription of amt-related nuclear gene decreased 3-9 fold in compensated bladders butincreased 10-30 fold in decompensated bladders. Activity for the cytochromeoxidase complex, and for the mt enzyme citrate synthase, decreased steadilywith increasing bladder hypertrophy. These data suggest that bladderdysfunction following partial outlet obstruction is mediated partly by asignificant loss in mt and mt-related nuclear gene coordination.
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    URL: http://dx.doi.org/10.1023/A:1006890527552
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    Oxidative phosphorylation in myocardial mitochondria 'in situ': a calorimetric study on permeabilized cardiac muscle preparations (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 101-113 
    Details
    ISSN: 1573-4919
    Keywords: calorimetry ; cardiac muscle ; mitochondria ; oxidative phosphorylation ; atractyloside ; dinitrophenol ; ectonucleotidase ; respiratory control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract A novel flow calorimetric technique was developed to study the energy turnover of myocardial mitochondria. Cylindrical strands of cardiac muscle (trabeculae) weighing 100–500 µg were isolated from guinea-pig heart and mounted in a tubular recording chamber which was continuously perfused with physiological salt solution at 37°C. The temperature difference between the upstream and the downstream side of the chamber, which is proportional to the rate of heat production of the trabecula, was measured at high resolution. In this way the rate of energy expenditure of isolated cardiac muscle could be recorded continuously for several hours. When the preparations were superfused with an 'intracellular' solution containing 5 mM pyruvate and 2 mM malate as substrates, permeabilization of the sarcolemma with 25 µM digitonin induced a marked increase in the measured heat rate in the presence of 2 mM ADP. The major fraction of the ADP sensitive heat production (83%) could be blocked with 400 µM at ractyloside, an inhibitor of the adeninenucleotide translocase, and by 600 µM α-cyano-4-hydroxycinnamate, an inhibitor of monocarboxylate/H+ co-transport. The atractyloside sensitive heat production was abolished in anoxic solution. These results suggest that the atractyloside-sensitive heat production (21.8 ± 3.5 mW cm-3 of tissue) was attributable to oxidative phosphorylation. The mitochondria apparently remained intact after treatment with digitonin, since application of the uncoupler 2,4-dinitrophenol (DNP) produced a very large increase in heat rate. A minor fraction of the heat rate induced by ADP in permeabilized cardiac muscle preparations (17%) was not sensitive to atractyloside. This component was also seen before application of digitonin and was probably related to ectonucleotidases. In conclusion, our calorimetric technique allows investigation of the energy metabolism of myocardial mitochondria 'in situ', i.e. without destroying the microarchitecture of cardiac muscle cells. (Mol Cell Biochem 174: 101–113, 1997)
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    Two modes of activation of the permeability transition pore: The role of mitochondrial cyclophilin (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 181-184 
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    ISSN: 1573-4919
    Keywords: mitochondria ; cyclosporin ; cyclophilin ; channels ; permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Mitochondria possess an inner membrane channel, the permeability transition pore, which is inhibited by cyclosporin A (CBA) and by matrix protons. As suggested recently by our laboratory, pore closure by these inhibitors may be due to dissociation of mitochondrial cyclophilin (CyP-M), a matrix peptidyl-prolyl-cis-trans isomerase, from its putative binding site on the pore. Unbinding of CyP-M would follow a CsA-dependent or proton-dependent change in conformation of the CyP-M molecule. It is interesting that upon binding of CsA the enzymatic activity of CyP-M is inhibited, but it is not clear whether this event plays a role in pore inhibition. Here we report experiments designed to further test the role of CyP-M in pore function. Our results indicate that CyP-M-dependent and independent mechanisms of pore activation may exist, and that the peptidylprolyl-cis-trans-isomerase activity of CyP-M is not necessarily involved in pore modulation by CyP-M. (Mol Cell Biochem 174: 181–184, 1997)
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    Hormonal stimulation, mitochondrial Ca2+ accumulation, and the control of the mitochondrial permeability transition in intact hepatocytes (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 173-179 
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    ISSN: 1573-4919
    Keywords: mitochondria ; calcium ; permeability transition ; vasopressin ; glucagon ; thapsigargin ; protein kineses and phosphatases ; rat hepatocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Ca2+ functions as an intracellular signal to transfer hormonal messages to different cellular compartments, including mitochondria, where it activates intramitochondrial Ca2+-dependent enzymes. However, excessive mitochondrial Ca2+ uptake can promote the mitochondrial permeability transition (MPT), a process known to be associated with cell injury. The factors controlling mitochondrial Ca2+ uptake and release in intact cells are poorly understood. In this paper, we investigate mitochondrial Ca2+ accumulation in intact hepatocytes in response to the elevation of cytosolic Ca2+ levels ([Ca2+]c) induced either by a hormonal stimulus (vasopressin), or by thapsigargin, an inhibitor of the endoplasmic reticulum Ca2+ pump. After stimulation, cells were rapidly permeabilized for the determination of the mitochondrial Ca2+ content (Ca2+_m) and to analyze the susceptibility of the mitochondria to undergo the MPT. Despite very similar levels of [Ca2+]c elevation, vasopressin and thapsigargin had markedly different effects on mitochondrial Ca2+ accumulation. Vasopressin caused a rapid (〈 90 sec), but modest (〈 2 fold) increase in Ca2+m that was not further increased during prolonged incubations, despite a sustained [Ca2+]c elevation. By contrast, thapsigargin induced a net Ca2+ accumulation in mitochondria that continued for up to 30 min and reached Ca2+_m levels 10–20 fold over basal. Accumulation of mitochondrial Ca2+ was accompanied by a markedly increased susceptibility to undergo the MPT. Both mitochondrial Ca2+ accumulation and MPT activation were modulated by treatment of the cells with inhibitors of protein kineses and phosphatases. The results indicate that net mitochondrial Ca2+ uptake in response to hormonal stimulation is regulated by processes that depend on protein kinase activation. These controls are inoperative when the cytosol is flooded by Ca2+ through artificial means, enabling mitochondria to function as a Ca2+ sink under these conditions. (Mol Cell Biochem 174: 173–179, 1997)
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    Point mutations in the mitochondrial tRNALys gene: Implications for pathogenesis and mechanism (1997)
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    Molecular and cellular biochemistry 174 (1997), S. 215-219 
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    ISSN: 1573-4919
    Keywords: MERRF ; mitochondria ; mtDNA ; genetics ; tRNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract MERRF (myoclonic epilepsy with ragged-red fibers) is a severe, multisystem disorder characterized by myoclonus, seizures, progressive cerebellar syndrome, muscle weakness, and the presence of ragged-red fibers in the muscle biopsy. MERRF is associated with heteroplasmic point mutations, either A8344G or T8356C, in the gene encoding the mitochondrial tRNALys. The human ro cell system was utilized to examine the phenotypic consequences of these mutations, and to investigate their molecular genetic causes. Wild-type and mutant transmitochondrial cell lines harboring a pathogenic point mutation at either A8344G or T8356C in the human mitochondrial tRNALys gene were isolated and examined. Mitochondrial transformants containing 100% mutated mitochondrial DNAs (mtDNAs) exhibited severe defects in respiratory chain activity, in the rates of protein synthesis, and in the steady-state levels of mitochondrial translation products as compared with mitochondrial transformants containing 100% wild-type mtDNAs. In addition, both mutant cell lines exhibited the presence of aberrant mitochondrial translation products. These results demonstrate that two different mtDNA point mutations in tRNALys result in fundamentally identical defects at the cellular level, and that these specific protein synthesis abnormalities contribute to the pathogenesis of MERRF. (Mol Cell Biochem 174: 215–219, 1997)
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    Alterations in susceptibility to carbon tetrachloride toxicity and hepatic antioxidant/detoxification system in streptozetocin-induced short-term diabetic rats: Effects of insulin and Schisandrin B treatment (1997)
    Springer
    Molecular and cellular biochemistry 175 (1997), S. 225-232 
    Details
    ISSN: 1573-4919
    Keywords: diabetes ; carbon tetrachloride ; liver toxicity ; glutathione ; mitochondria ; Schisandra chinensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The streptozotocin-induced short-term (2 week) diabetic rats showed an increase in susceptibility to carbon tetrachloride (CCl4)-induced hepatocellular damage. This diabetes-induced change was associated with a marked impairment in the hepatic glutathione antioxidant/detoxification response to CCl4 challenge, as indicated by the abrogation of the increases in hepatic reduced glutathione (GSH) level, glucose-6-phosphate dehydrogenase and microsomal glutathione S-transferases (GST) activities upon challenge with increasing doses of CCl4. While the hepatic GSH level was increased in diabetic rats, the hepatic mitochondrial GSH level and Se-glutathione peroxidase activity were significantly reduced. Insulin treatment could reverse most of the biochemical alterations induced by diabetes. Both insulin and schisandrin B (Sch B) pretreatments protected against the CCl4 hepatotoxicity in diabetic rats. The hepatoprotection was associated with improvement in hepatic glutathione redox status in both cytosolic and mitochondrial compartments, as well as the increases in hepatic ascorbic acid level and microsomal GST activity. The ensemble of results suggests that the diabetes-induced impairment in hepatic mitochondrial glutathione redox status may at least in part be attributed to the enhanced susceptibility to CCl4 hepatotoxicity. Sch B may be a useful hepatoprotective agent against xenobiotics-induced toxicity under the diabetic conditions. (Mol Cell Biochem 175: 225–232, 1997)
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    Phosphorylation of deoxyguanosine in intact and fractured mitochondria (1987)
    Springer
    Molecular and cellular biochemistry 77 (1987), S. 153-160 
    Details
    ISSN: 1573-4919
    Keywords: deoxyguanosine ; mitochondria ; deoxynucleoside metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The phosphorylation of deoxyguanosine was measured in fractured and intact mitochondria and an apparent Km of 16 μM for deoxyguanosine was calculated using fractured mitochondria. The effects of various deoxynucleotides on the phosphorylating activity in fractured organelles was tested at both a high and low ratio of NXP/ATP and at two pH values, 7.0 and 5.5. Exogenous dGTP, dGDP or dITP were inhibitory under all conditions tested. With a NXP/ATP ratio of 0.08 at pH 7.0, TTP, TDP, dADP, ADP, UTP and UDP were stimulatory, but at pH 5.5 only TTP elicited that response. When the NXP/ATP ratio was 10 at pH 5.5, TTP and UTP increased the activity more than 10-fold, whereas, at pH 7.0 TTP, TDP, dADP, ADP, UTP, UDP caused stimulation, but to a much lesser extent. When exogenous Mg2+, Mn2+ or Ca2+ were added to intact mitochondria, the rates of phosphorylation were lowered. In fractured mitochondria in the absence of exogenous ATP, little phosphorylation occurs, hence these metal ions caused little change. ATP-Mg, ATP-Mn and ATP-Ca, each at 0.05 mM caused a small inhibition with intact mitochondria, whereas, these compounds supported phosphorylation with fractured organelles. ATP-Mn (10 mM) or ATP-Ca (10 mM) stimulated phosphorylation in both intact and fractured mitochondria. Intact mitochondria synthesized dGMP, dGDP and dGTP when metal ion or ATP-Me concentrations were low (0.05 mM) or when Mg2+ concentration was high (10 mM). Additions of ATP-Ca, ATP-Mn, ATP-Mg, Mn2+ or Ca2+ at 10 mM cause the loss of dGDP and dGTP formation and, in most cases, an increase in the synthesis of dGMP. Fractured mitochondria make only dGMP and the levels of its synthesis are greater than that observed for intact mitochondria. These data suggest that intact mitochondria are required for the synthesis of dGTP and that its synthesis is regulated by mitochondria nucleotides.
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    Oxidation of Fe-8Cr-14Ni-Al-Si-Mn from 700 to 1000°C (1987)
    Springer
    Oxidation of metals 27 (1987), S. 103-120 
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    ISSN: 1573-4889
    Keywords: oxidation ; iron ; aluminum ; silicon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper reports an investigation into reducing the Cr concentration in commercial-grade stainless steels while maintaining oxidation protection at elevated temperatures. Aluminum and Si were added as partial substitute alloy elements to enhance the reduced operation protection resulting from Cr concentration reduced by approximately 50 pct of that found in stainless steels. The goal of this study was to determine the oxidation mechanism of such an Fe, Al-Si alloy: Fe-8Cr-14Ni-1Al-3.5Si-1Mn. During the initial oxidation period the protection resulted from a thin film of Al2O3 over an Fe and Cr spinel. Long-term oxidation protection resulted from the gradual formation of a Cr sesquioxide (Cr2O2) inner oxide layer. Eventually an outer oxide layer formed that was a mixed composition spinel of Cr and Mn (MnO · Cr2O3). The Al2O3, which was part of the original protective layer flaked off early in the oxide testing, and the aluminum oxide that formed later appeared as an internal oxide precipitate.
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    An approximate treatment of the transient state in the corrosion of binary alloys forming the most-stable oxide. Part I: Solid-solution alloys (1997)
    Springer
    Oxidation of metals 47 (1997), S. 91-115 
    Details
    ISSN: 1573-4889
    Keywords: binary alloys ; oxidation ; transient state ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The initial transient stage in the oxidation of binary alloys forming scales exclusively composed of the most stable oxide is examined by means of a simplified approach which avoids the numerical integration of the diffusion equation for the transport of the metal components in the alloy. At variance with previous solutions to this problem obtained by means of numerical methods, this treatment takes into account also the effect of the gas-scale reaction at the outer surface of the oxide. The concentration of the most-reactive component at the alloy surface changes gradually with time from the initial bulk value towards the corresponding steady-state value without involving any minimum, while the overall rate of the reaction presents a gradual transition from an initial nearly linear towards final parabolic behavior.
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    URL: http://dx.doi.org/10.1007/BF01682373
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    Oxidation resistance of sputtered Ni3(AlCr) nanocrystalline coating (1997)
    Springer
    Oxidation of metals 47 (1997), S. 247-258 
    Details
    ISSN: 1573-4889
    Keywords: Ni3Al-base alloy ; sputtering ; nanocrystalline coating ; oxidation ; scale adhesion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Isothermal and cyclic oxidation resistance at 1000°C in air were investigated for a cast Cr-containing Ni3Al-base alloy and its sputtered nanocrystalline coating. The results indicated that both the cast Ni3Al alloy and its sputtered coating exhibit excellent isothermal oxidation resistance as a result of the formation of Al2O3 scales. However, the cast alloy possesses very poor cyclic oxidation resistance because of the spallation of the initially formed Al2O3 scale during cooling and subsequent formation of NiO. On the contrary, the sputtered Ni3(AlCr) nanocrystalline coating exhibits very good cyclic oxidation resistance due to the significant improvement of the adhesion of Al2O3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01668513
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    The use of confocal microscopy in the investigation of cell structure and function in the heart, vascular endothelium and smooth muscle cells (1997)
    Springer
    Molecular and cellular biochemistry 172 (1997), S. 171-194 
    Details
    ISSN: 1573-4919
    Keywords: heart ; vascular endothelium ; vascular smooth muscle ; confocal microscopy ; pH ; calcium ; sodium ; voltage probe ; heart ; endothelin-1 ; Angiotensin II ; PAF ; nucleus ; mitochondria ; SR ; cardiomyopathy ; cells interaction ; R-type Ca2+ channel ; excitation-contraction coupling ; dystrophic mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract In recent years, fluorescence microscopy imaging has become an important tool for studying cell structure and function. This non invasive technique permits characterization, localisation and qualitative quantification of free ions, messengers, pH, voltage and a pleiad of other molecules constituting living cells. In this paper, we present results using various commercially available fluorescent probes as well as some developed in our laboratory and discuss the advantages and limitations of these probes in confocal microscopy studies of the cardiovascular system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006840228104
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    Reversibility of thiamine deficiency-induced partial necrosis and mitochondrial uncoupling by addition of thiamine to neuroblastoma cell suspensions (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 121-124 
    Details
    ISSN: 1573-4919
    Keywords: thiamine deficiency ; mitochondria ; energy metabolism ; necrosis ; neuroblastoma cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Culture of neuroblastoma cells in the presence of low thiamine concentration (6 nM) and of the transport inhibitor amprolium leads to the appearance of signs of necrosis: the chromatin condenses, the oxygen consumption decreases and is uncoupled, the mitochondrial cristae are disorganized, the thiamine diphosphate-dependent dehydrogenase activities are impaired. When 10 µM thiamine are added to these cells, the basal respiration increases, the coupled respiration is restored and mitochondrial morphology is recovered within 1 h. Addition of succinate, which is oxidized via a thiamine diphosphate-independent dehydrogenase, to digitonin-permeabilized cells immediately restores a coupled respiration. Our results suggest that the slowing of the citric acid cycle is the cause of the biochemical lesion induced by severe thiamine deficiency and that part of the mitochondria remain functional. (Mol Cell Biochem 174: 121–124, 1997)
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    URL: http://dx.doi.org/10.1023/A:1006842609998
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    Nitric oxide inhibition of cytochrome oxidase and mitochondrial respiration: Implications for inflammatory, neurodegenerative and ischaemic pathologies (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 189-192 
    Details
    ISSN: 1573-4919
    Keywords: nitric oxide ; mitochondria ; inflammation ; respiration ; astrocytes ; cytochrome oxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Nitric oxide (NO) at high levels is cytotoxic, and may be involved in a range of inflammatory, neurodegenerative, and cardiovascular/ischaemic pathologies. The mechanism of NO-induced cytotoxicity is unclear. Recently we and others have found that low (nanomolar) levels of NO reversibly inhibit mitochondrial respiration by binding to the oxygen binding site of cytochrome oxidase in competition with oxygen. This raises the apparent Km for oxygen of mitochondrial respiration into the physiological range, potentially making respiration sensitive to the oxygen level. The NO inhibition of oxygen consumption was seen in isolated cytochrome oxidase, mitochondria, brain nerve terminals, and cultured cells. Cultured astrocytes activated to express the inducible form of NO synthase produced up to 1 µM NO and strongly inhibited their own cellular respiration rate. This respiratory inhibition was rapidly reversed by removing the NO, and was due to the inhibition of cytochrome oxidase. These results suggest that any cell producing high levels of NO will inhibit its own respiration and that of surrounding cells, and make the respiration rate sensitive to the oxygen level. This inhibition of energy metabolism may contribute to cytotoxity or cytostasis in some pathologies. (Mol Cell Biochem 174: 189–192, 1997)
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    URL: http://dx.doi.org/10.1023/A:1006800322719
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    Identification of mitochondrial deficiency using principal component analysis (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 149-156 
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    ISSN: 1573-4919
    Keywords: mitochondria ; mitochondrial myopathies ; oxidative phosphorylation ; principal component analysis (PCA) ; biplot
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The mitochondrial pathologies are a heterogeneous group of metabolic disorders that are characterized by anomalies of oxidative phosphorylation, especially in the respiratory chain. The diagnosis of these pathologies involves many investigations among which biochemical study is at present the main tool. However, the analysis of the results obtained during such study remains complex and often does not make it possible to conclude clearly if a patient is affected or not by a biochemical and/or bioenergetic deficiency. This arises from two main problems: 1. The determination of control values from the whole set of variable values (affected and unaffected people). 2. The small size of the population studied and the large number of variables collected which present a rather large variability. To cope with these problems, the principal component analysis method is applied to the results obtained during our biochemical studies. This analysis makes it possible for each respiratory chain complex, to distinguish clearly two subsets of the whole population (affected and unaffected people) as well as to detect the variables which are the most discriminative. (Mol Cell Biochem 174: 149–156, 1997)
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    URL: http://dx.doi.org/10.1023/A:1006840218253
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    Mitochondrial, but not peroxisomal, β-oxidation of fatty acids is conserved in coenzyme A-Deficient rat liver (1997)
    Springer
    Molecular and cellular biochemistry 175 (1997), S. 37-42 
    Details
    ISSN: 1573-4919
    Keywords: mitochondria ; peroxisomes ; fatty acids metabolism ; coenzyme A deficiency ; pantothenic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Hepatic coenzyme A (CoA) plays an important role in cellular lipid metabolism. Because mitochondria and peroxisomes represent the two major subcellular sites of lipid metabolism, the present study was designed to investigate the specific impact of hepatic CoA deficiency on peroxisomal as well as mitochondrial β-oxidation of fatty acids. CoA deficiency (47% decrease in free CoA and 23% decrease in total CoA) was produced by maintaining weanling male Sprague-Dawley rats on a semipurified diet deficient in pantothenic acid (the precursor of CoA) for 5 weeks. Hepatic mitochondrial fatty acid oxidation of short-chain and long-chain fatty acids were not significantly different between control and CoA-deficient rats. Conversely, peroxisomal poxidation was significantly diminished (38% inhibition) in livers of CoA-deficient rats compared to control animals. Peroxisomal β-oxidation was restored to normal levels when hepatic CoA was replenished. It is postulated that since the role of hepatic mi tochondrial β-oxidation is energy production while peroxisomal β-oxidation acts mainly as a detoxification system, the mitochondrial pathway of β-oxidation is spared at the expense of the peroxisomal pathway when liver CoA plummets. The present study may offer an animal model to investigate mechanisms involved in peroxisomal diseases. (Mol Cell Biochem 175: 37–42, 1997)
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    URL: http://dx.doi.org/10.1023/A:1006877021617
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    Prevention of lens protein glycation by taurine (1997)
    Springer
    Molecular and cellular biochemistry 177 (1997), S. 245-250 
    Details
    ISSN: 1573-4919
    Keywords: cataract ; crystalline ; glycation ; oxidation ; taurine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Modifications in lens protein structure and function due to nonenzymic glycosylation and oxidation have been suggested to play a significant role in the pathogenesis of sugar and senile cataracts. The glycation reaction involves an initial Schiff base formation between the protein NH2 groups and the carbonyl group of a reducing sugar. The Schiff base then undergoes several structural modifications, via some oxidative reactions involving oxygen free radicals. Hence certain endogenous tissue components that may inhibit the formation of protein-sugar adduct formation may have a sparing effect against the cataractogenic effects of sugars and reactive oxygen. The eye lens is endowed with significant concentration of taurine, a sulfonated amino acid, and its precursor hypotaurine. It is hypothesized that taurine and hypotaurine may have this purported function of protecting the lens proteins against glycation and subsequent denaturation, in addition to their other functions. The results presented herein suggest that these compounds are indeed capable of protecting glycation competitively by forming Schiff bases with sugar carbonyls, and thereby preventing the glycation of lens proteins per se. In addition, they appear to prevent oxidative damage by scavenging hydroxyl radicals. This was apparent by their preventive effect against the formation of the thiobarbituric acid reactive material generated from deoxy-ribose, when the later was exposed to hydroxyl radicals generated by the action of xanthine oxidase on hypoxanthine in presence of iron.
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    URL: http://dx.doi.org/10.1023/A:1006863322454
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    The metabolism of deoxyguanosine in mitochondria. Characterization of the uptake process (1987)
    Springer
    Molecular and cellular biochemistry 77 (1987), S. 71-77 
    Details
    ISSN: 1573-4919
    Keywords: mitochondria ; deoxyguanosine ; deoxynucleoside metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary The uptake of deoxyguanosine by rat liver mitochondria was characterized. The process required an intact mitochondrial membrane and exhibited a dependence on added phosphate. Deoxyguanosine uptake was minimally influenced by Mg2+ or Mn2+, but Ca2+ at concentrations above 0.5 mM were detrimental. Of the deoxynucleosides tested, only deoxyinosine inhibited the uptake of deoxyguanosine. The ribonucleoside guanosine was not observed to compete with its deoxynucleoside analog. Known inhibitors of nucleoside transport, cytochalasin B and NBMPR, did not block deoxyguanosine uptake, but the sulfhydryl reagents NEM and pCMB were both inhibitory. The uptake of deoxyguanosine was shown to be a saturable process and an apparent Km of 0.64 σM was calculated from a Hanes plot.
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    URL: http://dx.doi.org/10.1007/BF00230152
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    Sol-Gel Coatings on Metals (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 443-449 
    Details
    ISSN: 1573-4846
    Keywords: coatings ; protection of metals ; oxidation ; corrosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Sol-gel derived films can be deposited on metals to improve their resistance to oxidation and corrosion or to modify their surface properties. However, practical applications are limited by problems intrinsic to sol-gel processing or specific of coating/metal systems. Coatings aimed to improve oxidation and wet corrosion resistance have been the most studied. The results published in the literature show that sol-gel coatings may offer good protection against oxidation. More difficult is to achieve a protection against wet corrosion. An important aspect of the application of the sol-gel method for coating metallic objects is also the deposition technique.
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    URL: http://dx.doi.org/10.1023/A:1018373404815
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    Sol-gel coatings on metals (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 443-449 
    Details
    ISSN: 1573-4846
    Keywords: coatings ; protection of metals ; oxidation ; corrosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Sol-gel derived films can be deposited on metals to improve their resistance to oxidation and corrosion or to modify their surface properties. However, practical applications are limited by problems intrinsic to sol-gel processing or specific of coating/metal systems. Coatings aimed to improve oxidation and wet corrosion resistance have been the most studied. The results published in the literature show that sol-gel coatings may offer good protection against oxidation. More difficult is to achieve a protection against wet corrosion. An important aspect of the application of the sol-gel method for coating metallic objects is also the deposition technique.
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    URL: http://dx.doi.org/10.1007/BF02436880
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    Kinetics and mechanisms of the oxidation of chromium in H2-H2O-H2S gas mixtures (1987)
    Springer
    Oxidation of metals 28 (1987), S. 73-98 
    Details
    ISSN: 1573-4889
    Keywords: chromium ; oxidation ; sulfidation ; mixed oxidants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of pure chromium in H2-H2O-H2S gas mixtures was studied as a function of gas composition at 900°C. Oxidation kinetics were measured using a thermogravimetric apparatus, and the oxidation products were characterized using scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM). Chromia scales formed when the H2O/H2S ratio was about 10 or greater. Scales that comprised a mixture of Cr2O3 and chromium sulfides formed when the H2O/H2S ratio was about 3, even though Cr2O3 was the thermodynamically stable phase under these conditions; i.e., a kinetic boundary exists for pure chromium in H2-H2O-H2S gas mixtures. The transition from chromia scale formation to the formation of scales containing both oxide and sulfide with a change in gas composition (decrease in the H2O/H2S ratio) is associated with an inhibition of the overgrowth of growing, metastable sulfide nuclei by the thermodynamically stable Cr2O2 phase. Presulfidation experiments confirmed that metastable chromium sulfide can continue to grow after H2O is added to the gas phase when the H2O/H2S ratio in the gas phase is less than a critical value at the temperature of interest.
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    URL: http://dx.doi.org/10.1007/BF00666472
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    Influence of silicon on the oxidation of titanium between 550 and 700°C (1987)
    Springer
    Oxidation of metals 27 (1987), S. 1-20 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; titanium ; silicon ; adherence ; titanium-silicon alloys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation behavior of Ti-Si alloys (0.25, 0.5, and 1 Wt. % Si) was investigated between 550 and 700°C; in oxygen by continuous thermogravimetry for a maximum duration of about 500 hr and, in air by daily weighing for durations from a few hundred to several thousand hours. The kinetics results revealed that the presence of silicon leads to a decrease in oxidation rate which is more evident when the temperature is raised and the silicon content is increased. Morphological and structural examinations revealed that silicon modifies the internal architecture of oxide layers when compared with unalloyed titanium; in particular, reduced porosity in the layers is observed. Analysis showed that silicon is uniformly distributed in the oxide layer. However, while part of the silicon is in solid solution in the rutile, some is also precipitated as small crystals (φ 〈1 μm at 850°C) of SiO2, of cristobalite structure. The adherence of oxide layers to the metal substrate was measured after cooling of samples; the addition of silicon has been observed to modify, in a manner dependent on its content, the adherence of oxide layers.
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    URL: http://dx.doi.org/10.1007/BF00656726
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    Accelerated oxidation rate of chromium induced by sodium chloride (1987)
    Springer
    Oxidation of metals 27 (1987), S. 315-332 
    Details
    ISSN: 1573-4889
    Keywords: chromium ; NaCl ; oxidation ; hot corrosion ; mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation rate of NaCl-coated chromium was measured over the temperature range of 823–1043 K. Although the melting point of NaCl is 1074 K, accelerated oxidation was observed at every temperature. Oxidation mass-gain curves were divided into two types. Type I involved only accelerated oxidation during the initial stage followed by the formation of a thin protective Cr2O3 film. Type II pertained to an acceleration over a long time, forming a thick and nonprotective Cr2O3film containing Na2CrO4. The former type of oxidation occurred at lower temperatures or with a small amount of NaCl, whereas the latter occurred at higher temperatures and with large amounts of NaCl. A comparison of these oxidation processes with those by CaCl2 or BaCl2, revealed two problems: (1) Why was the oxidation rate of chromium so high in the presence of NaCl?, and (2) Why did the high oxidation rate continue for such a long time?
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    URL: http://dx.doi.org/10.1007/BF00659274
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    Kinetics of the oxidation of metals: Parallel circuit for point defects diffusion (1987)
    Springer
    Oxidation of metals 27 (1987), S. 301-314 
    Details
    ISSN: 1573-4889
    Keywords: diffusion mechanisms ; point defects ; oxidation ; NiO-V2O5
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A model is proposed for the oxidation of metals including both bulk crystal lattice diffusion and short-circuit diffusion paths. Assuming local equilibrium between point defects in the bulk and in grain boundaries, we obtain an effective parabolic rate constant keff=kbulk [1+θ exp-(ΔH/RT],where ΔH is the enthalpy for the reaction between point defects in the bulk and in short circuits, θ is the fraction of the short-circuit area, and T is temperature. In the case of the high-temperature oxidation of nickel coated with a thin film of vanadium pentoxide, this model yields to a rate law with a critical oxygen pressure P c. The nickel vanadium oxide located in the short circuits of the growing oxide NiO is liquid below Pc, leading to a rapid short-circuit diffusion. Above this value, a vanadate precipitates and acts as diffusion blocks for migrating Ni ions.
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    The air oxidation of two-phase Cu-Ag alloys at 650–750°C (1997)
    Springer
    Oxidation of metals 47 (1997), S. 21-52 
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    ISSN: 1573-4889
    Keywords: copper ; silver ; high temperature ; oxidation ; two-phase alloys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The corrosion of three two phase Cu-Ag alloys containing 25, 50, and 75 wt% Ag has been studied at 650 and 750°C. In all cases the alloys formed external scales of copper oxides. At the same time, an internal precipitation of Cu2O within a silver matrix was also produced, with an oxide volume fraction larger for the alloys richer in Cu. Beneath this mixed layer a region of single-phase solid solution of Cu in silver formed for Cu-50Ag and especially for Cu-75Ag. Silver metal remained in the metal-consumption zone, acting essentially as an inert marker, except for a few particles with were incorporated into the growing scales. Both pure Cu and the alloys corroded parabolically, but the rate constants for the alloys decreased with increased Ag content under constant temperature. The various aspects of the corrosion of these alloys are examined by taking into account the possible effects associated with the presence of two metal phases.
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    Identification of diffusing species and the dynamic nature of diffusion paths during oxidation of a dilute Ni-Cr alloy (1997)
    Springer
    Oxidation of metals 47 (1997), S. 69-89 
    Details
    ISSN: 1573-4889
    Keywords: duplex-layer formation ; dynamic oxygen-diffusion path ; Ni-Cr alloy ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The results of an investigation of oxidation of a Ni-1 at.% Cr alloy are presented. Photolithographic marker experiments revealed that the markers were found to reside at the interface between a predominantly columnar outer NiO layer and a very fine grain inner layer of NiO, indicating that substantial oxygen ingress had occurred through the columnar scale. New oxide growth at the metal-oxide interface requires the oxidant to be transported across the oxide layer. Since the measured diffusion rate of oxygen ions along grain boundaries and through the lattice is much too slow to account for the observed microstructural growth (∼1: 1 ratio of inner and outer layers), it is necessary to postulate that the oxidant traverses the scale along some type of short-circuit path other than grain boundaries. Extensive formation of elongated pores and pipelike channels was observed along columnar oxide grain boundaries. Thus, it appears that the transport of oxygen occurs via voids (pores) formed by vacancy coalescence at the columnar grain boundaries. These pores appear to open and close continuously. Formation of new fine-grained oxide in these pores was observed to have sometimes completely resealed the void, suggesting a dynamic nature of the voids.
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    Oxidation of the intermetallics MoSi2 and TiSi2—A comparison (1997)
    Springer
    Oxidation of metals 47 (1997), S. 139-203 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; MoSi2 ; TiSi2 ; air ; oxygen ; O and Si transport in SiO2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation behavior of two MoSi2 variants, one Mo-rich and one Si-rich, and TiSi2 was investigated between 1000 and 1400°C in air, oxygen and an 80/20-Ar/O2 mixture. A protective SiO2 scale develops on MoSi2 in all atmospheres in the temperature range investigated. The SiO2 modification changes around 1300°C from tridymite to cristobalite. This change in SiO2 modification seems to cause an enhanced formation of SiO2 and evaporation of MoO3. The SiO2 grows at the MoSi2-scale interface. In air a two-layer scale grows on TiSi2 between about 1000 and 1200°C with an inner inwards growing fine-grain mixture of SiO2 + TiO2 and an outer outward-growing TiO2 partial layer. TiN formation in the transient oxidation is responsible for the formation of the inner mixed partial layer because in N -free atmospheres a scale of a SiO2 matrix with some Ti oxide precipitates inside is formed. A one-layer scale structure similar as that in N-free atmosphere is found on TiSi2 in air at T 〉 1200°C. In oxygen the TiO2 precipitates grow as needles mostly oriented perpendicular to the surface. Due to the faster oxygen transport in TiO2 compared with SiO2, these TiO2 needles act as “oxygen pipes,” causing an enhanced oxidation of TiSi2 in front of these needles. The SiO2 scale dissolves about 1–2% TiO2. This doping causes a mixed oxygenand Si transport with the consequence that the SiO2 scale on TiSi2 grows partly by oxygen transport inwards and Si transport outwards. The SiO2 modification is cristobalite over the entire temperature range investigated.
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    URL: http://dx.doi.org/10.1007/BF01682375
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    The steady-state corrosion kinetics of single-phase binary alloys with a solubility gap forming the most-stable oxide (1997)
    Springer
    Oxidation of metals 47 (1997), S. 215-235 
    Details
    ISSN: 1573-4889
    Keywords: high temperature ; oxidation ; binary alloys ; steady-state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The steady-state, high-temperature oxidation kinetics of single phase alloys rich in a most-reactive componentB in binaryA-B systems presenting a limited solubility of the two components (beta phase alloys) have been examined assuming the exclusive formation of the most-stable oxideBO v. Alloys sufficiently rich inB can form externalBO v scales directly in contact with the beta phase, while below a criticalB content the growth ofBO v involves also the appearance of an intermediate layer ofB-depleted solid solution ofB inA (alpha phase). The parabolic rate constants for the oxidation of single-phase beta alloys are lower than those of alloys of identicalB content which are single-phase over the whole range of composition (solid-solution alloys) but higher than for two-phase alpha + beta alloys under the same values of all the relevant parameters. Moreover, the tendency of single-phase beta alloys to form the most-stable oxide simultaneously as an external scale and internally to the alloy is greater than for solid-solution alloys but smaller than for two-phase alloys.
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    URL: http://dx.doi.org/10.1007/BF01668511
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    High-temperature oxidation behavior of laser-surface-alloyed incoloy-800H with Al (1997)
    Springer
    Oxidation of metals 47 (1997), S. 259-275 
    Details
    ISSN: 1573-4889
    Keywords: laser surface alloying ; aluminum ; superalloys ; oxidation ; microstructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The high-temperature oxidation resistance of laser-surface-alloyed Incoloy 800H with Al has been investigated. Several samples have been exposed to 1000°C in air and subsequently analyzed by optical microscopy, SEM, and electron microprobe X-ray fluorescence spectroscopy in order to determine their microstructure and composition. The results show that the laser-treated materials have a considerably higher oxidation resistance than the nontreated materials due to the formation of an Al-rich layer close to the surface, which acts as a barrier against oxygen diffusion into the bulk.
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    URL: http://dx.doi.org/10.1007/BF01668514
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    Insulin as a probe of mitochondrial metabolism in situ (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 91-96 
    Details
    ISSN: 1573-4919
    Keywords: insulin ; mitochondria ; Krebs cycle ; pyruvate ; succinate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Our previous studies of insulin action have led us to the finding that insulin acts specifically on the mitochondrial Krebs cycle to stimulate, by 30%, the oxidation of carbons 2 and 3 of pyruvate to CO2. Insulin also stimulates the oxidation of both carbons of acetate. These carbons can be converted to CO2 only after passing through all of the reactions of the Krebs cycle more than once. Carboxyl groups, such as number 1 of pyruvate, are oxidized to CO2 without any effect of insulin, and can be converted to CO2 by extramitochondrial enzyme. We conclude that insulin must act on the complete intramitochondrial cycle and not on the four enzymes of the Krebs cycle which are present in the cytoplasm. The path taken by those carbons affected by insulin is traced through the complete Krebs cycle, and the necessity for this effect to be mitochondrial has been verified by demonstration of the same specific effect of insulin on the oxidation of the 2 and 3 carbons of succinate. The use of this phenomenon is proposed for the study not only of human diabetes, but of all mitochondrial disorders, by using 14C specifically labeled tracers in culture or biopsy material, or 13C labeled tracer material in vivo. (Mol Cell Biochem 174: 91–96, 1997)
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    URL: http://dx.doi.org/10.1023/A:1006834408181
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  • 91
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    Inhibition of complex I by neuroleptics in normal human brain cortex parallels the extrapyramidal toxicity of neuroleptics (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 255-259 
    Details
    ISSN: 1573-4919
    Keywords: mitochondria ; neuroleptics ; oxidative phosphorylation ; complex I
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract There is increasing evidence that a defect of the mitochondrial respiratory chain is implicated in the development of Parkinson disease. Decreased complex I activity of the mitochondrial respiratory chain has been reported in platelets, muscle, and brain of patients with Parkinson disease. Extrapyramidal symptoms (e.g. parkinsonism and dystonic reactions) are major limiting side effects of neuroleptics. Experimental evidence suggests that neuroleptics inhibit complex I in rat brain. There has not been a study of the effects of neuroleptics in human tissue, however. We therefore analyzed the activities of complexes I + III, complexes II + III, succinate dehydrogenase, complex IV (cytochrome c oxidase), and of citrate synthase in normal human brain cortex after the addition of haloperidol and chlorpromazine and the atypical neuroleptics risperidone, zotepine, and clozapine. Activity of complex I was progressively inhibited by all neuroleptics. Half maximal inhibition (IC50) was 0.1 mM fo r haloperidol, 0.4 mM for chlorpromazine, and 0.5 mM for risperidone and zotepine. Clozapine had no effect on enzyme activity at concentrations up to 0.5 mM, followed by a slow decline with a maximum inhibition of 70% at 10 mM. IC50 was at about 2.5 mM. Thus, the concentration of clozapine needed to cause 50% inhibition of the activity of complexes I and III was about 5 times that of zotepine and risperidone, about 6 times that of chlorpromazine, and 25 times that of haloperidol. The inhibition thus paralleled the incidence of extrapyramidal effects caused by the different neuroleptics as they are known from numerous clinical studies. Our data support the hypothesis that neuroleptic-induced extrapyramidal side effects may be due to inhibition of the mitochondrial respiratory chain. (Mol Cell Biochem 174: 255–259, 1997)
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    URL: http://dx.doi.org/10.1023/A:1006872911332
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    Mitochondrial abnormalities and peripheral europathy in inflammatory myopathy, especially inclusion body myositis (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 277-281 
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    ISSN: 1573-4919
    Keywords: mitochondria ; myopathy ; inclusion body myositis ; neuropathy ; vasculitis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Computer retrieval in a database, comprising 7,225 muscle cases, revealed that mitochondrial myopathies do not occur more frequently in inflammatory myopathies (3.74%) than in the whole series (3.69%). A more detailed study of inclusion body myositis (IBM), however, showed that severe mitochondrial alterations were apparent in about twice as many IBM cases as expected. This confirms recent studies of others although a causal relationship has thus far not been established. Identification of mitochondrial deletions by Southern blotting corresponded to the presence of severe structural abnormalities of mitochondria. Peripheral neuropathy of variable severity was noted in all cases of IBM and mitochondrial myopathy. By contrast, the association of severe mitochondrial abnormalities with polymyositis, systemic scleroderma, and vasculitis observed in some cases of the present series may be incidental or age dependent. (Mol Cell Biochem 174: 277–281, 1997)
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    URL: http://dx.doi.org/10.1023/A:1006829129079
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  • 93
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    Hg(II)-induced renal cytotoxicity: In vitro and in vivo implications for the bioenergetic and oxidative status of mitochondria (1997)
    Springer
    Molecular and cellular biochemistry 177 (1997), S. 53-59 
    Details
    ISSN: 1573-4919
    Keywords: mercury ; rat kidney ; mitochondria ; oxidative phosphorylation ; FoF1-ATPase ; ATP synthesis ; ATP hydrolysis ; oxidative stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The effects of Hg(II) on bioenergetic and oxidative status of rat renal cortex mitochondria were evaluated both in vitro, and in vivo 1 and 24 h after treatment of animals with 5 mg HgCl2/kg ip. The parameters assessed were mitochondrial respiration, ATP synthesis and hydrolysis, glutathione content, lipid peroxidation, protein oxidation, and activity of antioxidant enzymes. At low concentration (5 µM) and during a short incubation time, Hg(II) uncoupled oxidative phosphorylation while at slightly higher concentration or longer incubation time the ion impaired the respiratory chain. The rate of ATP synthesis and the phosphorylation potential of mitochondria were depressed, although inhibition of ATP synthesis did not exceed 50%. In vivo, respiration and ATP synthesis were not affected 1 h post-treatment, but were markedly depressed 24 h later. ATP hydrolysis by submitochondrial particle FoF1-ATPase was inhibited (also by no more than 50%) both in vitro, and in vivo 1 and 24 h post-treatment. Hg(II) induced maximum ATPase inhibition at about 1 uM concentration but did not have a strong inhibitory effect in the presence of Triton X-100. Oxidative stress was not observed in mitochondria 1 h post-treatment. However, 24 h later Hg(II) reduced the GSH/GSSG ratio and increased mitochondrial lipid peroxidation and protein oxidation, as well as inhibited GSH-peroxidase and GSSG-reductase activities. These results suggest that the following sequence of events may be involved in Hg(II) toxicity in the kidney: (1) inhibition of FoFl-ATPase, (2) uncoupling of oxidative phosphorylation, (3) oxidative stress-associated impairment of the respiratory chain, and (4) inhibition of ATP synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006861319378
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  • 94
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    Macromolecular interaction and the electrophoretic mobility of esterase-5 from Drosophila pseudoobscura (1987)
    Springer
    Biochemical genetics 25 (1987), S. 287-307 
    Details
    ISSN: 1573-4927
    Keywords: macromolecular interactions ; temperature ; electrophoresis ; esterase-5 ; Drosophila pseudoobscura
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Esterase-5 is one of the most polymorphic loci in Drosophila pseudoobscura. Some variants reportedly produce a dimeric enzyme, while a few produce a monomeric form. This paper reports the finding that during electrophoresis ESTERASE-5 exists in a dynamic equilibrium between monomers and dimers, an equilibrium that is dependent on the running temperature of the gels. This is shown by a series of analytical electrophoresis experiments in which the apparent molecular weights of several variants are determined at four different temperatures. Increasing temperatures result in a linear decrease in the logarithm of apparent molecular weights. Macromolecular interactions thus are a significant determinant of EST-5 electrophoretic mobility.
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    URL: http://dx.doi.org/10.1007/BF00499322
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  • 95
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    Characterization and temperature regulation of soluble proteins of a male sterile tomato mutant (1987)
    Springer
    Biochemical genetics 25 (1987), S. 717-728 
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    ISSN: 1573-4927
    Keywords: male sterility ; mutant ; proteins ; temperature ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The soluble proteins of the normal and male-sterile stamenless-2 (sl-2/sl-2) mutant of tomato(Lycopersicon esculentum) grown in different temperatures were analyzed by one- and two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The normal and mutant stamens had some common proteins, but certain proteins were either present or more enriched in one genotype than in the other. The other floral organs of the normal and mutant showed no major differences in proteins, suggesting that the sl-2/sl-2 allele is active primarily in anther development. Normal and mutant stamens grown in high temperatures were enriched in some proteins in comparison to the intermediate temperatures. At low temperatures, the protein pattern of normal and mutant stamens was essentially similar.
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    URL: http://dx.doi.org/10.1007/BF00556214
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  • 96
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    Hyperthyroidism and Mitochondrial Uncoupling (1997)
    Springer
    Bioscience reports 17 (1997), S. 17-21 
    Details
    ISSN: 1573-4935
    Keywords: Hyperthyroidism ; mitochondria ; uncoupling ; proton-leak ; pump-slip
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract During the past years many efforts have been made to elucidate the origin of the uncoupling mechanisms induced by hyperthyroidism in mitochondria. Two main mechanisms have been proposed: a classical protonophoric uncoupler mechanism, considering the action of thyroid hormones at the level of the lipid membrane bilayer, and a slipping mechanism with more localized effects at the level of the redox proton pumps. This short review is devoted to comparing and discussing the evidence against and in favour of these two mechanisms.
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    URL: http://dx.doi.org/10.1023/A:1027379000027
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  • 97
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    The Role of Reactive Oxygen Species in Mitochondrial Permeability Transition (1997)
    Springer
    Bioscience reports 17 (1997), S. 43-52 
    Details
    ISSN: 1573-4935
    Keywords: Calcium ; cyclosporin A ; lipid peroxidation ; mitochondria ; mitochondrial membrane permeability transition ; protein oxidation ; reactive oxygen species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We have provided evidence that mitochondrial membrane permeability transition induced by inorganic phosphate, uncouplers or prooxidants such as t-butyl hydroperoxide and diamide is caused by a Ca2+-stimulated production of reactive oxygen species (ROS) by the respiratory chain, at the level of the coenzyme Q. The ROS attack to membrane protein thiols produces cross-linkage reactions, that may open membrane pores upon Ca2+ binding. Studies with submitochondrial particles have demonstrated that the binding of Ca2+ to these particles (possibly to cardiolipin) induces lipid lateral phase separation detected by electron paramagnetic resonance experiments exploying stearic acids spin labels. This condition leads to a disorganization of respiratory chain components, favoring ROS production and consequent protein and lipid oxidation.
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    URL: http://dx.doi.org/10.1023/A:1027335217774
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  • 98
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    Role of the Mitochondrial Permeability Transition Pore in Apoptosis (1997)
    Springer
    Bioscience reports 17 (1997), S. 67-76 
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    ISSN: 1573-4935
    Keywords: Apoptosis ; necrosis ; mitochondria ; megachannel ; permeability transition ; programmed cell death ; poteases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Mitochondrial permeability transition (PT) involves the formation of proteaceous, regulated pores, probably by apposition of inner and outer mitochondrial membrane proteins which cooperate to form the mitochondrial megachannel (=mitochondrial PT pore). PT has important metabolic consequences, namely the collapse of the mitochondrial transmembrane potential, uncoupling of the respiratory chain, hyperproduction of superoxide anions, disruption of mitochondrial biogenesis, outflow of matrix calcium and glutathione, and release of soluble intermembrane proteins. Recent evidence suggests that PT is a critical, rate limiting event of apoptosis (programmed cell death): (i) induction of PT suffices to cause apoptosis; (ii) one of the immediate consequences of PT, disruption of the mitochondrial transmembrane potential (ΔΨm), is a constant feature of early apoptosis; (iii) prevention of PT impedes the ΔΨm collapse as well as all other features of apoptosis at the levels of the cytoplasma, the nucleus, and the plasma membrane; (iv) PT is modulated by members of the apoptosis-regulatory bcl-2 gene family. Recent data suggest that the acquisition of the apoptotic phenotype, including characteristic changes in nuclear morphology and biochemistry (chromatin condensation and DNA fragmentation), depends on the action of apoptogenic proteins released from the mitochondrial intermembrane space.
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    URL: http://dx.doi.org/10.1023/A:1027339418683
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  • 99
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    The Non-Ohmic Proton Leak—25 Years On (1997)
    Springer
    Bioscience reports 17 (1997), S. 251-257 
    Details
    ISSN: 1573-4935
    Keywords: Leak ; mitochondria ; proton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The proton conductance of the mitochondrial inner membrane can be quantified by applying Ohm's law to the experimentally determined protonmotive force and the proton current flowing around the proton circuit in the absence of ATP synthesis or ion transport. This last parameter is derived from the rate of State 4 respiration multiplied by the H+/O stoichiometry for the substrate. When the activity of the dehydrogenase supplying electrons to the respiratory chain is progressively increased the proton conductance increases rapidly when the protonmotive force is greater than 220 mV. The consequences of this non-ohmic relationship are discussed.
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    URL: http://dx.doi.org/10.1023/A:1027376426860
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  • 100
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    Generating, Partitioning, Targeting and Functioning of Superoxide in Mitochondria (1997)
    Springer
    Bioscience reports 17 (1997), S. 259-272 
    Details
    ISSN: 1573-4935
    Keywords: Superoxide ; hydrogen peroxide ; electron leak ; proton leak ; H+/2e ; membrane potential ; reactive oxygen cycle ; heat production ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Recently, we proposed a hypothetical model of coexistence of “Reactive oxygen cycle” with Q cycle and H+ cycle in mitochondrial respiratory chain to combine both processes of univalent electron leak for production of superoxide and of proton leak across inner mitochondrial membrane. This review presents a more detailed description of this model and summarizes the supporting experimental evidence obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1027328510931
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