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  • Spektralphotometrie  (167)
  • oxidation  (57)
  • Phytochrome  (56)
  • Springer  (280)
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • Wien : Geolog. Bundesanst.
  • 2010-2014
  • 2005-2009
  • 1975-1979  (280)
  • 1940-1944
Collection
Publisher
  • Springer  (280)
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • Wien : Geolog. Bundesanst.
Years
Year
  • 1
    ISSN: 1432-2048
    Keywords: Citrate synthase ; Fat degradation ; Isocitrate lyase ; Malate synthase ; Phytochrome ; Sinapis ; Starch (transitory)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The degradation of storage fat in the cotyledons of mustard seedlings is unaffected by phytochrome and photosynthesis (irradiation with continuous red or far-red light from sowing of the seeds) although light imposes a strong constraint on the translocation of organic matter from the cotyledons into the seedling axis. Likewise, the development and disappearance of glyoxysomal enzyme activities (isocitrate lyase, malate synthase, citrate synthase) takes place independently of light. It is concluded that the mobilization of storage fat (fat→carbohydrate transformation) is independent of photomorphogenesis. The surplus of carbohydrate produced from fat in the light seems to be converted to starch grains in the plastids, which function as a secondary storage pool in the cotyledons.
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  • 2
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    Planta 146 (1979), S. 31-39 
    ISSN: 1432-2048
    Keywords: Autoradiography ; Calcium ; Mougeotia ; Phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ca2+ is proposed to function as a messenger in such phytochrome-mediated responses as localized cell growth, intracellular movements, and control of plasma membrane properties. To test this hypothesis, the uptake of Ca2+ in irradiated and non-irradiated regions of individual threads of the green alga Mougeotia was studied with the aid of 45Ca2+ and low temperature autoradiography: 10–20 cells within 40–60 cell-long threads were irradiated for up to 1 min, transferred to darkness for 3 to 10 min, submersed in a radioactive medium for 1 min, washed in an unlabelled medium for 30 min, and then autoradiographed at-80° C for several days. The autoradiographs show that those cells which had been pre-irradiated with red light did take up 2–10 times more Ca2+ than the adjacent non-irradiated cells of the same thread. Cells pre-irradiated with farred light or red light followed by far-red light showed no enhanced uptake of Ca2+. These results might be interpreted to indicate, firstly, that phytochrome-Pfr is involved in the enhanced uptake of Ca2+ and secondly, that the accumulation of radioactive Ca2+ in red light irradiated cells is an expression of an increased intracellular concentration of Ca2+. This interpretation is based on the data that (i) the dark interval between irradiation and labelling precluded the involvement of photosynthesis, (ii) the effect of red light was reversible with far-red light, and (iii) the accumulation of Ca2+ persisted during the long wash-out period. We speculate, that the red light-enhanced accumulation of Ca2+ in Mougeotia cells is caused by a Pfr-mediated increase of the Ca-permeability of the plasma membrane, and perhaps by a Pfr-impeding of an active Ca2+-extrusion.
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  • 3
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    Planta 147 (1979), S. 229-235 
    ISSN: 1432-2048
    Keywords: Avena ; Greening ; Mitochondria ; Oxidative Phosphorylation ; Phytochrome ; Respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mitochondria isolated from 7-day old darkgrown Avena sativa L. (var. Arnold) laminae given 5 min illumination of red light, followed by varying lengths of darkness up to 3 h, showed at least a twofold increase in the rates of both NADH-dependent oxygen consumption and respiratory chain phosphorylation over those of mitochondria isolated from unilluminated tissue. Similar organelles, isolated from tissue given either far-red or red followed by far-red pretreatment, exhibited rates of both functions of between 25% and 75% below those of the mitochondria from unilluminated tissue. The induction-reversion criteria for phytochrome control of respiration and oxidative phosphorylation were satisfied under all experimental conditions during the greening process. Treatment with continuous far-red light, acting presumably through the ‘high irradiance’ reaction of phytochrome, served to disengage phytochrome activity from photosynthesis. The stimulation of oxidative phosphorylation still occurred under these conditions, slightly slower but much more prolonged in the absence of ATP from photophosphorylation.
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  • 4
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    Planta 145 (1979), S. 405-409 
    ISSN: 1432-2048
    Keywords: Chenopodium ; Internode elongation ; Photoreception sites ; Phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The elongation of the fourth internode of ‘fully green’ Chenopodium polyspermum L. is modulated by far-red light (FR) given in addition to the main light period. Two different types of organs are responsible for the photoreception of FR producing the end-of-day effect; the stem and the leaves situated just above and below the reacting internode. Photoreversibility can be obtained within certain limits in the two organs. Evidence is presented which shows that in the ‘fully green’ plant there is an interorgan reaction whose primary reaction is the photoconversion of phytochrome.
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  • 5
    ISSN: 1432-2048
    Keywords: Carotenoids ; Chlorophylls ; Herbicides ; Phytochrome ; Plastid development ; Ribulosebisphosphate carboxylase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Treatment of the mustard (Sinapis alba L.) seedling with the herbicide SAN 9789 inhibits synthesis of colored carotenoids and interferes with the formation of plastid membrane lipids without affecting growth and morphogenesis significantly. In farred light, which is hardly absorbed by chlorophyll, development of plastid ultrastructure, synthesis of ribulosebisphosphate carboxylase and synthesis of chlorophyll are not affected by SAN 9789. It is concluded that normal phytochrome actions on plastid structural development, protein and chlorophyll syntheses are not affected by the absence of carotenoids provided that there is no significant light absorption in chlorophyll. The findings show that the inhibition of synthesis of one set of plastid membrane components (the carotenoids) does not stop synthesis of other components such as chlorophyll and does not halt membrane assembly. Supplementary experiments with the closely related compound SAN 9785, which affects the amount and composition of plastid lipids but not carotenoid and chlorophyll syntheses, suggest that the effect of the herbicide SAN 9789 is due exclusively to its inhibition of synthesis of colored carotenoids. In the presence of SAN 9789 white or red light at high fluence rate causes photodestruction of chlorophyll and ribulosebisphosphate carboxylase and photodecomposition of thylakoids. These effects are interpreted as resulting exclusively from the self-photooxidation and photosensitizing action of chlorophyll once the protection by carotenoids of chlorophyll against self- and sensitized photooxidation is lost.
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  • 6
    ISSN: 1432-2048
    Keywords: Phytochrome ; Development habitat ; Natural radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A survey of the responsiveness of plant species, typical of open and shade habitats, to simulated natural shade-light quality (i.e. white light plus supplementary far-red) has demonstrated a systematic relationship between habitat and certain developmental responses. Supplementary far-red light has a much greater effect on stem extension rate, petiole length, and leaf dry weight: stem dry weight ratio of the open habitat, shade-intolerant species. Far-red effects on leaf chlorophyll content show no such systematic grading. These results are discussed in relation to habitat adaptation. In most cases, the relationship between developmental response and the estimated phytochrome photoequilibrium, which is established by the radiation treatment, is linear. This is taken as an indication of phytochrome involvement in shade perception.
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  • 7
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    Planta 145 (1979), S. 269-272 
    ISSN: 1432-2048
    Keywords: Flowering ; Gibberellin ; Photoperiodism ; Phytochrome ; Sorghum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Combinations of far-red light (FR) (4 min) and gibberellic acid (GA3), given at the beginning of a daily 12-h dark period in a growth room, were used to study floral induction in four maturity genotypes of the milo group of sorghum (Sorghum bicolor (L.) Moench). The 12-h dark period without GA3 application or FR induced flowering in only the early genotype; FR hastened initiation in the early genotype, while GA3 hastened floral initiation in the two intermidiate-flowering genotypes. GA3 and FR together had a strong synergistic effect, hastening floral initiation by 30 to more than 80 d in the early and intermediate genotypes. Red light (R) did not hasten flowering; FR preceded by R gave the same effect as FR alone. GA3 promoted stem elongation equally whether floral initiation occurred or not; thus, its effect on stem elongation was independent of floral initiation. The capacity of GA3 to induce flowering in sorghum, a short-day plant, seems to be enhanced by phytochrome being in the PR form at the beginning of the night when GA3 was applied.
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  • 8
    ISSN: 1432-2048
    Keywords: Action spectrum ; Dormancy (seeds) ; Germination (seeds) ; Lactuca ; Phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Light of wavelengths in the range 400–500 nm induces germination of seeds of Lactuca sativa L. (cv. Noran and May Queen) when made light requiring by high temperature (thermodormancy) or prolonged exposure to far red light (far red dormancy). TD seeds proved more sensitive to blue light than FRD seeds by several orders of magnitude. Blue induced germination could be reversed by far red. Fluence response curves for this reversion are less steep for TD than for FRD seeds. The degree of germination of TD seeds after moderate doses of blue light is decreased by dark storage at 22° C or by exposure to far red and this is accompanied by a marked change in the shape of the fluence response curves. In these respects, germination induction by blue resembles that by red light. Continuous exposure to blue light inhibits germination of TD seeds but hardly that of FRD seeds. An action spectrum is given for blue induced germination of TD seeds.
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  • 9
    ISSN: 1432-2048
    Keywords: Action spectra ; Dormancy (seeds) ; Germination (seeds) ; Lactuca ; Phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Fluence response curves for red light-induced germination of thermodormant (TD) seeds of Lactuca sativa L. show two regions that differ in their light sensitivity. In the region of high sensitivity, the germination responses differ between seed batches and can be altered by dark storage or far red irradiation. Induction of germination in far red dormant (FRD) seeds requires far higher fluences. Action spectra for induction to 60% germination were determined for these various response types. Spectra for the regions of low sensitivity response are similar for TD and FRD seeds. In comparison, the action spectrum for the highly sensitive response in TD seeds is significantly shifted to longer wavelengths. Analogous differences exist in the action spectra for far red reversal of the red induced germination responses. Germination induction in the low sensitivity region shows repeated red-far red reversibility. Far red reversal of red induction in the high sensitivity region does not saturate even at the highest far red fluences available and requires increased red fluences for subsequent reinduction. A model quantitatively accounting for these observations is presented. It is pointed out that action spectra of processes involving photoreversible pigments with partly overlapping absorption spectra in general are not identical with the absorption spectra of the partners. They should depend upon the degree of phototransformation required to elicit a given physiological response. In the case of induction of lettuce seed germination the observed action spectra can be interpreted as reflecting different requirements for P fr of the various response types. Our results do not necessitate the assumption of spectroscopically different forms of phytochrome in these seeds.
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  • 10
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    Planta 146 (1979), S. 75-81 
    ISSN: 1432-2048
    Keywords: Adenosine-5′-triphosphate ; Membrane ; Phaseolus ; Phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a membrane fraction isolated from hypocotyls of Phaseolus aureus Roxb. the activity of a number of enzymes was regulated by red and far-red irradiation in vitro, provided that the tissue received a brief red light treatment before extraction. Other enzymes showed no photoregulation. There were two types of photocontrol, neither of which could be detected in the solute fraction, nor in extracts from completely etiolated material. One (Type I) was a red/far-red reversible regulation of the rate of enzyme activity, depending on the light given (in vivo or in vitro) before the assay was begun. The second (Type II) was a promotion of enzyme activity by red or far-red light given during the assay. The action spectra for type II responses do not coincide with either the phytochrome absorption or difference spectra. However, the effectiveness of red and far-red was correlated with the Pfr/P ratio present at the beginning of the assay, such that far-red was more efficient at high Pfr/P and red at low Pfr/P ratios. All enzymes that were regulated involved ATP. In samples that showed enzyme regulation, small changes in fluorescence yield of tryptophan and the covalent probe “Fluram” (Roche) accompanied the photoconversion of phytochrome, but no fluorescence changes could be measured after briefly incubating the membrane fraction with ATP. The results indicate that light may affect the interaction of ATP with the membrane fraction.
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  • 11
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    Planta 147 (1979), S. 1-5 
    ISSN: 1432-2048
    Keywords: Polyribosomes ; Phytochrome ; Raphanus ; Ribonucleases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The total ribosome content of radish cotyledons increases during the first 2–3 days of germination both in darkness and under far-red light irradiation; ribonuclease activity is not under phytochrome control during this period. Changes in ribonuclease activity interfere with the analysis of the polyribosomal population. A maximal ratio of polysomes to monosomes is observed 12 h after the onset of far-red light and then it decreases. A 12 h far-red irradiation stimulates the in vivo incorporation of amino acids into proteins. This stimulation persists when seedlings are transferred for 4 h to the dark.
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  • 12
    ISSN: 1432-2048
    Keywords: Cell wall ; Cytoplasm ; β-Fructosidase (transfer) ; Phytochrome ; Raphanus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The far-red absorbing form of phytochrome, Pfr, rapidly increases the rate of transfer of β-fructosidase (E.C.3.2.1.26) from the cytoplasm to the cell wall in radish hypocotyls. Far-red light increases the level of enzyme in a particulate fraction: after two hours of light treatment, the particulate enzyme is associated almost exclusively with the endoplasmic reticulum. Transfer from the endoplasmic reticulum to the cell wall involves an incorporation into Golgi bodies and the plasmalemma: these membrane fractions were separated by centrifugation on a discontinuous sucrose density gradient and their degree of purity was determined by the use of known biochemical markers. With respect to β-fructosidase, light controls, via Pfr: (1) the total amount, (2) the incorporation into the endoplasmic reticulum and (3) the transfer to the cell-wall. These three processes have different sensitivities to cycloheximide.
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  • 13
    ISSN: 1432-2048
    Keywords: Anthocyanin ; Mode of action of phytochrome ; Phenylalanine ammonia-lyase ; Phytochrome ; Sinapis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Induction by light of phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) and of anthocyanin in cotyledons of the mustard (Sinapis alba L.) seedling is strongly affected by a light pretreatment which operates through phytochrome. If PAL or anthocyanin is induced by a light pulse, the effectiveness of phytochrome (Pfr) is strongly increased by a light pretreatment; however, if the increase of the PAL level or synthesis of anthocyanin is elicited by continuous far-red light (operating via phytochrome in the ‘High Irradiance Response’), effectiveness of light is strongly reduced by the same light pretreatment. This reduction of effectiveness is correlated with a decrease of total phytochrome (Ptot) caused by the light pretreatment. It is argued that the observations are compatible only with the ‘open phytochrome-receptor model’ as suggested by Schäfer (J. Mathem. Biol. 2, 41–56, 1975). The peaks of the time courses of the PAL levels under continous far-red light are located at 48 h after sowing and do not depend on the original level of phytochrome. The decrease of the PAL levels beyond 48 h after sowing takes place independently of phytochrome and of the actual level of PAL.
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  • 14
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    Planta 146 (1979), S. 415-417 
    ISSN: 1432-2048
    Keywords: Germination (seeds) ; Osmotic stress ; Phytochrome ; Seed germination ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Maize caryopses sown in water germinate equally well either in darkness or under any light regime. However, when they are imbibed in mannitol solutions, continuous far-red light proves to be strongly inhibitory on the final germination as compared to darkness. Similar but less pronounced inhibition is also exhibited by continuous red or blue light. Intermittent far-red light can partially substitute for continuous far-red light in inhibiting maize caryopsis germination, and its effect is reversed to the intermittent red light level when red light is given immediately after each far-red illumination. These results are interpreted as a proof of existence and involvement of phytochrome in the germination control of maize caryopses, though its manifestation is realized only under osmotic stress.
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  • 15
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    Planta 146 (1979), S. 545-550 
    ISSN: 1432-2048
    Keywords: Blue light ; Cucumis ; Hypocotyl growth ; Lactuca ; Lycopersicon ; Phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of blue light on hypocotyl extension in de-etiolated seedlings of lettuce, cucumber and tomato was investigated under conditions which precluded the involvement of phytochrome. Small but highly inhibitory amounts of blue light were added to a high intensity background illumination from low pressure sodium lamps. A log-linear response for inhibition of hypocotyl extension against the blue light fluence rate was obtained for lettuce and cucumber, and inhibition in tomato was also related to the blue light fluence rate. The added blue light did not alter phytochrome photostationary state and its effect was independent of the total fluence rate. Growth inhibition by Pfr could be demonstrated in tomato and cucumber but not in lettuce. The results indicate that two photoreceptors may normally be involved in the control of seedling growth but their relative importance varies greatly between species.
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  • 16
    ISSN: 1432-2048
    Keywords: Chenopodium ; Day light fluence rate ; End-of-day effect ; Internode elongation ; Phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The elongation of the fourth internode of fully green Chenopodium polyspermum L. is strongly stimulated by far-red light (FR) given at the end of the day. The end-of-day effect is more important when the plants had been cultivated for several days with a main light period of 140 Wm-2 than with a main light period of 85 Wm-2. There exists a quantitative relationship between the FR end-of-day effect mediated by phytochrome and the value of the light fluence during the day.
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  • 17
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    Oxidation of metals 13 (1979), S. 181-195 
    ISSN: 1573-4889
    Keywords: copper-manganese alloys ; oxidation ; scale composition
    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 copper-manganese alloys (2–35 wt. % Mn) in pure oxygen at 760 Torr was investigated at 100° intervals between 550 and 850°C. Gravimetric measurements of the oxidation kinetics have been combined with microstructural studies of the reacted samples in order to evaluate the reaction mechanisms. The scales formed on Cu-2Mn, Cu-5Mn, Cu-10Mn are always composed of three different layers; in any case manganese is present only in the inner layer. The scales formed on Cu-20Mn and Cu-35Mn are composed of two layers, both containing manganese, with a more Cu-rich outer layer. In all the samples internal oxidation in combination with external scale formation is observed.
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  • 18
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    Oxidation of metals 13 (1979), S. 283-298 
    ISSN: 1573-4889
    Keywords: oxidation ; surface alloys ; Fe-Cr alloys ; iron ; 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 several surface and bulk Fe-Cr alloys and iron at 300°C and 4×10−6 Torr oxygen was studied. The surface alloys were fabricated by implantation of 25 keV Cr ions into the outermost 300Å of polycrystalline iron samples. The oxide thickness as a function of oxygen exposure was obtained using proton-excited X-ray analysis, and composition profiles of oxide films were obtained using Auger electron spectroscopy and ion sputtering. The addition of Cr to Fe by surface and bulk alloying caused the oxidation rate to decrease and changed the oxidation kinetics from parabolic (for Fe) to logarithmic (for Cr concentrations ≥4.7at.%). Interpretation of the data in terms of simple oxidation theories indicates that the Cr additions may reduce the oxidation rate by altering the electronic properties of the metal-oxide interface.
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  • 19
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    Oxidation of metals 13 (1979), S. 311-330 
    ISSN: 1573-4889
    Keywords: oxidation ; oxide maps ; alloying additives ; Fe-Ni-Al 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 iron-nickel-aluminum alloys containing 0–40 wt.% nickel and 0–30 wt.% aluminum has been investigated at 600 and 800° C. Through the construction of “oxide maps” it can be shown that three possible oxide morphologies may exist: Alloys containing less than approximately 5 wt.% aluminum form scales consisting of predominantly Fe2O3 and spinel; alloys with between 5 and 10 wt.% aluminum form Al2O3 scales interspersed by Fe2O3 nodules, and alloys with greater than 10 wt.% aluminum form predominantly γ-Al2O3 scales.
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  • 20
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    Oxidation of metals 13 (1979), S. 223-236 
    ISSN: 1573-4889
    Keywords: nickel ; oxidation ; surface reactions ; X-ray photoelectron spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract X-ray photoelectron spectroscopy has been used to study the oxidation of polycrystalline nickel metal. The results indicate that the oxidation process takes place in three stages; associative adsorption of molecular oxygen, followed by the combination of oxygen atoms with surface nickel atoms and, ultimately, the formation of bulk oxide. At room temperature only the first two stages can be detected. For exposures below 1 L the O 1s photoelectron spectrum is considered to be characteristic of an associatively adsorbed oxygen species, but for exposures above this value evidence for the formation of a monolayer of “NiO” is suggested by the development of an O 1s peak at 529.9 eV. Incorporation of oxygen into the nickel lattice is observed at temperatures 〉500°K. The activation energy for this place-exchange process was estimated at 1.80±0.06 eV.
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  • 21
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    Oxidation of metals 13 (1979), S. 255-272 
    ISSN: 1573-4889
    Keywords: oxidation ; Fe-C ; graphite deposition ; nonadherent oxide ; 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 Fe-C alloys containing 0.5 and 1.0% C was studied in 1 atm O2 at 700° C. The oxidation rate is considerably slower than for pure Fe. The oxide scale formed is detached, multilayered, and overoxidized, containing little or no FeO. A thin film of graphite was identified at the metal-oxide interface by electron diffraction. It is proposed that the slow oxidation and abnormal scale are caused by a residue of graphite left at the metal surface from the oxidation of Fe3C. This inhibition of the oxidation of Fe by carbon at 700°C is in contrast to the stimulation observed at 500°C.
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  • 22
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    Oxidation of metals 13 (1979), S. 519-543 
    ISSN: 1573-4889
    Keywords: nickel ; oxidation ; transport ; tracer ; duplex scale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Experimental techniques have been developed for determining Ni63 and O18 tracer distributions in NiO scales ranging in thickness from ∼0.1 to 100 μ. These have been used to investigate Ni and O transport in scales on {100} Ni crystals and polycrystalline Ni in the temperature range 500–1300° C. NiO grown on {100} Ni crystals at 1000°C was uniform and compact and grew by the bulk diffusion of Ni in NiO by a vacancy mechanism. At temperatures below 800°C the principal transport mechanism was short-circuit diffusion of Ni in NiO. At all temperatures short-circuit diffusion of oxygen contributed to scale growth on polycrystalline Ni and was responsible for growth of the inner layer of duplex scales. The oxygen diffusion paths are believed to be micro-cracks induced by growth stresses.
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  • 23
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    Oxidation of metals 13 (1979), S. 159-180 
    ISSN: 1573-4889
    Keywords: nickel-chromium alloys ; oxidation ; high temperature ; cerium
    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 Ni-50Cr alloys with minor cerium additions was studied between 800 and 1100° Cin oxygen, air, and oxygen at reduced partial pressures. Optical and scanning electron metallography, X-ray diffraction, and electron-probe microanalysis techniques were used to characterize the changes in scale and substrate morphology and to identify the oxidation products. Platinum markers were used to determine the direction of ionic transport. The effects of cold work, initial alloy phase distribution, and cyclic oxidation were also studied. The Cr 2 O 3 scales on the cerium-containing alloys grew while being largely separated from the metal substrate. Oxidation rate, oxide grain growth, and the tendency of scales to spall on cooling were reduced substantially with increasing alloy cerium content. The first two effects are suggested to result from the interaction of cerium ions and cerium oxide particles with oxide grain boundaries in reducing grain-boundary diffusion and oxide-boundary mobility. The third is suggested to result from the thinner, finer-grained scales formed on the Ce-containing alloys.
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  • 24
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    Oxidation of metals 13 (1979), S. 437-456 
    ISSN: 1573-4889
    Keywords: Fe-Cr ; oxidation ; kinetics ; oxide morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Ferritic polycrystalline Fe-24 wt.% Cr was oxidized in pure oxygen at 190 ≤ T≤490° C and pressures in the range 5.3×10−2–13.3 Pa for periods of up to 5 hr. The reaction proceeded in three stages. An initial period of accelerating rate was accompanied by oxide island nucleation and growth. Following island coalescence the rate was approximately logarithmic at low temperatures and somewhat slower than parabolic at high temperatures. Rate control during this period was thought to be due to mass transport through the oxide grain boundaries left by the island impingement process. During these first two stages the oxide formed was γ-M2O3 with possibly some spinel. The final stage of reaction involved the appearance of α-M2O3 on the outer oxide surface and a substantial slowing of the oxidation rate due to the low diffusivity in this phase.
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  • 25
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    Oxidation of metals 13 (1979), S. 119-158 
    ISSN: 1573-4889
    Keywords: nickel-chromium alloys ; oxidation ; high temperature ; kinetics ; mechanisms
    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 binary Ni-Cr alloys containing 44 and 50 wt. % Cr has been studied over a range of oxygen partial pressures at temperatures between 800 and 1100°C. The effects of cold work, surface preparation, and distribution of the Cr-rich second phase have been studied. The oxidation behavior is complex and cannot be described by a single model. The oxide grows by short-circuit diffusion as well as bulk transport through Cr 2 O 3 scales. The scale-growth mechanism includes extensive metal-oxide separation requiring Cr vapor transport to the scale, compressive stresses within the oxide which result in scale bulging and cracking, and the formation of a second oxide layer which results in voids being incorporated into the scale. Any factor which reduces the oxide grain size, such as cold work, finer distribution of the Cr-rich α phase or reduced oxygen pressure, results in an increased oxidation rate of binary alloys because of an increased number of grain-boundary short-circuit diffusion paths.
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    Oxidation of metals 13 (1979), S. 331-351 
    ISSN: 1573-4889
    Keywords: oxidation ; copper ; thin films ; electron microscopy ; electron diffraction
    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 thin single-crystal (100) and (111) films of copper at pressures of around 10−5 Torr and temperatures of 400 to 700°C has been observed by medium-energy electron diffraction, scanning electron microscopy, scanning and conventional microscopy using diffracted electron beams in the reflection mode, transmission electron microscopy, and transmission electron diffraction. Epitaxed nuclei of oxide are observed to grow into very thin single-crystal plates, using oxygen previously trapped in the copper film. There is considerable diffusion of the copper film. There is considerable diffusion of the copper away from the oxide. Between the oxide crystallites the copper surfaces appear to be unoxidized. A mottled contrast of the diffracted beam images of the copper surface is shown to result from many-beam dynamical diffraction effects.
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    Oxidation of metals 13 (1979), S. 381-401 
    ISSN: 1573-4889
    Keywords: Co-Cr-Al ; oxidation ; dispersed oxides ; oxide scale adherence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The improvement in oxidation resistance produced by small additions of active elements to Al 2O3-forming CoCrAl alloys is primarily dependent on the formation of oxide pegs which grow into the alloy around the internal oxide particles of the active element; void formation at the alloy-scale interface is also suppressed. The distribution of these pegs is critical and this paper demonstrates that an internal oxidation pretreatment can be used to convert the active element to its oxide in a controlled manner, thereby optimizing the peg distribution. Al2O3-forming CoCrAl containing 1% Hf or Ce is internally oxidized in a sealed quartz capsule containing a 50/50 powder mixture of CoAl-Al2O3; it was not possible to oxidize internally Y-containing alloys. The isothermal and cyclic oxidation resistance of these alloys is superior to that of alloys not given a prior treatment. Detailed metallographic examination indicates that the prior internal oxidation treatment produces a finer, more uniform distribution of oxide pegs penetrating into the alloy which is more efficient in combatting scale spallation. Furthermore, the lower residual hafnium content in the alloy minimizes large HfO2 precipitates and the formation of gross Al2O3 intrusions, which can initiate scale failure. Thus, by internally oxidizing the alloy first, the advantages of a high alloy Hf content (1%) in producing sufficient oxide pegs, but of the right size, coupled with minimal thickening of the surface scale, can be achieved.
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    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 367-372 
    ISSN: 1618-2650
    Keywords: Best. von Lanthaniden, Europium, Dysprosium, Erbium, Samarium in Uran ; Spektralphotometrie ; Atomabsorption ; Graphitofen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary Studies were conducted on the assay of Sm, Eu, Dy and Er separated from uranium using aqueous standards by electrothermal AAS with Massmann type graphite furnace. The working curves were found to be linear in the ranges Sm (1–10 μg/ml), Eu (0.05–0.6 μg/ml), Dy (0.1–0.8 μg/ml) and Er (0.1–1.0 μg/ml). The values obtained for synthetic samples agreed favourably with those obtained by emission spectrographic method. Experiments using pyrolytic carbon coated tubes with and without pretreatment by La, Ta and Y have shown an enhancement with treatment upto a maximum of 15% and improve the memory effect marginally. The effect of Ta treatment was found to be singularly useful in improving the general behaviour of Sm. The interference effects of lanthanides, other than the analyte, were found to be negligible. However, the presence of uranium was found to affect the absorbance. The absorbance of Eu was found to be nearly independent of uranium after an initial increase. On the other hand, the absorbance of other elements studied was found to drastically decrease after an initial enhancement. Detailed investigations of temperature dependence of absorbance were carried out using Eu, Dy and Er. The differences in the behaviour of these elements is attributed to probable differences in the modes of their atomization.
    Notes: Zusammenfassung Die Untersuchungen wurden mit Hilfe des Graphitrohrofens nach Maßmann durchgeführt. In folgenden Bereichen ergaben sich lineare Eichkurven: Sm 1–10 μg/ml, Eu 0,05–0,6 μg/ml, Dy 0,1–0,8 μg/ml, Er 0,1μ-1,0 μg/ml. Die aus synthetischen Proben erhaltenen Ergebnisse stimmten gut mit den durch Emissionsspektrographie erhaltenen überein. Versuche wurden mit Röhren mit pyrolytischen Kohlenstoffüberzug mit und ohne Vorbehandlung durch La, Ta und Y durchgeführt und ergaben eine bis 15%ige Steigerung durch die Behandlung sowie eine mäßige Besserung des Memoryeffektes. Eine Behandlung mit Ta war besonders für Sm vorteilhaft. Störungen durch andere Lanthanide waren vernachlässigbar. Uran beeinflußte jedoch die Absorption. Im Falle von Eu zeigte sich nach anfänglicher Zunahme fast eine Unabhängigkeit, während bei den anderen untersuchten Elementen nach anfänglicher Zunahme eine beträchtliche Abnahme auftrat. Mit Eu, Dy und Er wurde ebenfalls die Temperaturabhängigkeit der Absorption untersucht. Festgestellte Unterschiede im Verhalten werden auf unterschiedliche Atomisierung zurückgeführt.
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 284-284 
    ISSN: 1618-2650
    Keywords: Best. von Uran(VI) mit Chlorphosphonazo III ; Spektralphotometrie ; Trioctylamin-Extraktion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 285-285 
    ISSN: 1618-2650
    Keywords: Best. von Phosphat in Ferrosilicium ; Spektralphotometrie ; Cer/Xylenolorange, indirekt
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    Topics: Chemistry and Pharmacology
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 413-413 
    ISSN: 1618-2650
    Keywords: Best. von Kobalt mit Pyridin und Azid ; Spektralphotometrie ; Aussalzungsmittel, Mischkomplex
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    Topics: Chemistry and Pharmacology
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 270-270 
    ISSN: 1618-2650
    Keywords: Best. von Cer(IV) ; Spektralphotometrie ; indirekt, Fe(III)-Resacetophenonoximat-Komplex
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    Fresenius' Zeitschrift für analytische Chemie 299 (1979), S. 264-266 
    ISSN: 1618-2650
    Keywords: Best. von Kohlenhydraten in Huminsäuren ; Spektralphotometrie ; Anthronmethode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Eine modifizierte Anthronmethode zur Bestimmung des Kohlenhydratgehaltes in Fraktionen von Huminsäure-Blei(II)-Chelatverbindungen, die mit chemischen und gelchromatographischen Methoden getrennt wurden, wird beschrieben. Um die Störung der Methode durch die Absorption der Huminsäuren, die mit abnehmender Wellenlänge ansteigt, gering zu halten, wird die Extinktion des Anthron-Kohlenhydrat-Reaktionsproduktes bei 620 nm gemessen. Die Huminsäurekonzentration darf 0,1 g/dl nicht überschreiten. Da die molare Extinktion des Anthron-Reaktionsproduktes von der Art des Kohlenhydrates abhängt, wird der Kohlenhydratgehalt auf das Hauptkohlenhydrat des Huminsäurehydrolysats berechnet (d.h. Glucose).
    Notes: Summary A modified anthrone method is described for the determination of carbohydrates in fractions of lead(II)-chelate compounds of humic acids separated with chemical as well as gel-chromatographic methods. To reduce the disturbance of the method by the absorption of humic acids increasing with the decrease of wavelength, the absorbance of the anthronecarbohydrate reaction products is measured at 620 nm and the humic acid concentration is not allowed to exceed 0.1 g/dl. Because the molar absorptivity of the anthrone reaction-products depends on the type of carbohydrate investigated, the content is calculated for the main carbohydrate of the humic-acid hydrolysate (i.e. glucose).
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 366-370 
    ISSN: 1618-2650
    Keywords: Best. von Quecksilber, Silber mit Formazanen ; Spektralphotometrie ; chelatbildende Ionenaustauscher
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Darstellung substituierter Formazane und ihre chemische Fixierung an Cellulose, amino- und chlormethyliertem Polystyrol wird beschrieben. Die Kapazitäten der Austauscher liegen zwischen 0,05 mÄq/g (Cellulose) und 0,6 mÄq/g (Polystyrol). In neutralem Medium zeigen sie eine besondere Affinität zu Hg(II), Pd(II) und Ag(I), aber keine Affinität zu Cu(II). Weiterhin wurde eine spektrophotometrische Bestimmung von Hg(II) und Ag(I) mit dem wasserlöslichen Formazan (FII)-NO2 ausgearbeitet [Hg(II): ɛ546=23 000 l Mol−1 cm−1, Ag(I): ɛ546 =38 000 l Mol−1 cm−1].
    Notes: Summary The preparation of substituted formazans and their fixation on cellulose, amino- and chloromethylated polystyrene is described. The capacities of the exchangers vary from 0.05 meq/g (cellulose) to 0.6 meq/g (polystyrene). They show in neutral medium greater affinity to Hg(II), Pd(II) and Ag(I), but no affinity to Cu(II). Further, a spectrophotometric determination of Hg(II) and Ag(I) with the watersoluble formazan (FII)-NO2 has been worked out. [Hg(II): ɛ546=23 000 l Mol−1 cm−1, Ag(I): ɛ546=38 000 l Mol−1 cm−1].
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 356-360 
    ISSN: 1618-2650
    Keywords: Spektralphotometrie ; Mechanisierung, Prinzip, Optimierung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Das Prinzip der Automatisierung der photometrischen Analyse mit kontinuierlichem Reagentienfluß und die speziellen Vorteile der Verwendung von Bausteinen der Flüssigkeits-Chromatographie werden ausführlich diskutiert. Die Optimierung folgender Parameter wird besprochen: Verweilzeit (Reaktionszeit), Einspritzmenge, Pumpgeschwindigkeit, Säulenabmessungen, Partikeldurchmesser.
    Notes: Summary The principle of automation of photometric analysis by the continuous flow method and the particular advantages of the use of component parts of liquid chromatography are discussed in detail. The optimization of the following parameters is pointed out: residence (reaction) time, injection volume, pumping rate, column dimensions and particle diameter.
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 47-47 
    ISSN: 1618-2650
    Keywords: Best. von Vanadium in Stahl ; Spektralphotometrie ; Hydroxyphenyl-p-tolylbenzamidin
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    Topics: Chemistry and Pharmacology
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 393-397 
    ISSN: 1618-2650
    Keywords: Best. von Tensiden in Wasser ; Spektralphotometrie ; Aniontenside, Reinigungsstufen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Aniontenside werden an Feststoffen der Gewässer wie auch der Kläranlagen adsorbiert und teilweise angereichert. Ihre analytische Bestimmung erfordert eine mehrstufige Vorarbeit. Sie führt über die Extraktion des Probengutes, die Abtrennung der Tenside von Störstoffen durch Ausblasen (grobe Vorreinigung) und die chromatographische Reinigung der Rohfraktion auf Kieselgelschichten. Die Konzentration der reinen Tensidfraktion kann colorimetrisch oder IR-spektrometrisch bestimmt werden.
    Notes: Summary Anion tensides are adsorbed on solids in surface waters and sewage treatment plants and enriched to some extent. Their analytical determination requires multi-stage preparations, including sampling, separation of the tensides from disturbing material by air stripping (rough preliminary cleaning), and chromatographic cleaning of the raw fraction on silica gel. The concentration of the pure tenside fraction can be determined colorimetrically or by way of IR spectrometry.
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    Fresenius' Zeitschrift für analytische Chemie 297 (1979), S. 159-160 
    ISSN: 1618-2650
    Keywords: Best. von Vanadium(V) mit p-Hydroxybenzaldehyd und Hydroxyamidin ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 158-158 
    ISSN: 1618-2650
    Keywords: Best. von Palladium, Ruthenium ; Spektralphotometrie ; Isonitrosodibenzoylmethan
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    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 160-160 
    ISSN: 1618-2650
    Keywords: Best. von Ruthenium(III) mit 3-Hydroxy-3-(p-dimethylaminophenyl)-1-phenyltriazen ; Spektralphotometrie
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    Fresenius' Zeitschrift für analytische Chemie 296 (1979), S. 45-45 
    ISSN: 1618-2650
    Keywords: Best. von o-Dichlorbenzol ; Spektralphotometrie ; UV
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    Fresenius' Zeitschrift für analytische Chemie 296 (1979), S. 46-46 
    ISSN: 1618-2650
    Keywords: Best. von p-Methylaminophenolsulfat, Metol ; Spektralphotometrie
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    Fresenius' Zeitschrift für analytische Chemie 296 (1979), S. 406-407 
    ISSN: 1618-2650
    Keywords: Best. von Ligninsulfonsäure, Huminsäure in Wasser ; Spektralphotometrie ; UV
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    Fresenius' Zeitschrift für analytische Chemie 296 (1979), S. 383-385 
    ISSN: 1618-2650
    Keywords: Best. von Bor in Silicaten ; Spektralphotometrie ; Pyrohydrolyse, Carminsäure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary This simple method for the determination of boron takes a total time of 20 min. Samples are mixed with CaF2 suprapur in the ratio 3∶1 and pyrohydrolized in a Leco induction furnace for 15 min under steam of H2O. The BF3 liberated is collected in a NaOH-Na2CO3 solution (10 g NaOH +1 g Na2CO3 per liter). This solution is filled up to 200 ml with twice distilled water; 2 ml of this solution is mixed with conc. sulphuric acid and carminic acid solution and filled up to 50 ml. The absorption is measured by a Zeiss Elko II photometer with filter S 59. Analyses of four internations reference samples show excellent precision with a relative standard deviation of less than 5% (e.g. for a boron content of 2.1 ppm in granite G-2).
    Notes: Zusammenfassung Die Borbestimmung mit dieser schnellen und einfachen Methode benötigt ca. 20 min. Die Proben werden mit CaF2 Suprapur im Verhältnis 3∶1 vermischt und in einem Leco-Induktionsofen 15 min unter Einleitung von Wasserdampf pyrohydrolysiert. Das entstandene BF3 wird in einer NaOH-Na2CO3-Lösung(10 g NaOH+1 gNa2CO3pro Liter) aufgefangen. Diese Lösung wird mit zweifach destilliertem Wasser auf 200 ml aufgefüllt; 2 ml dieser Lösung werden mit konz. Schwefelsäure und Carminsäure-Lösung versetzt und auf 50 ml aufgefüllt, bevor ihre Absorption mit einem Zeiss — Elko II — Photometer mit Filter S 59 gemessen wird. Analysen von 4 internationalen Referenzproben zeigen eine hohe Präzision mit einer relativen Standardabweichung von weniger als 5% (z. B. für einen Gehalt von 2,1 ppm Bor im Granit G-2 des USGS).
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    Fresenius' Zeitschrift für analytische Chemie 296 (1979), S. 407-408 
    ISSN: 1618-2650
    Keywords: Best. von N-p-Tolylbenzohydroxamsäure ; Spektralphotometrie
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    Fresenius' Zeitschrift für analytische Chemie 296 (1979), S. 414-415 
    ISSN: 1618-2650
    Keywords: Best. von Quecksilber(II) mit 3-Methyl-5-pyrazolon-4-dithiocarbonsäure ; Spektralphotometrie
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 286-286 
    ISSN: 1618-2650
    Keywords: Best. von Aminen mit Isothiocyanatodioxotolyldihydrobenzisochinolin ; Spektralphotometrie
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 285-285 
    ISSN: 1618-2650
    Keywords: Best. von Eisen(III), Chrom(VI) mit Helasolviolett 4R ; Spektralphotometrie
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 119-121 
    ISSN: 1618-2650
    Keywords: Best. von Wolfram(VI) mit Thioglykolsäure ; Spektralphotometrie ; Chelatbildung, Carbonsäuren
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung W(VI) bildet mit Thioglykolsäure und Glykolsäure mäßig stabile Fünfringchelate der Zusammensetzung WR2, mit Glycin ein sehr schwaches WR. Chelate mit den Sechsringbildnern 3-Mercaptopropionsäure und o-Mercaptobenzoesäure sind nicht nachweisbar. Das Thioglykolsäurechelat kristallisiert aus Methanol als gelbes Na-Salz WO2(SCH2COONa)2·2CH3OH und ist mit Di-phenylguanidin als Ionenpaar in Butanol extrahierbar. Die photometrische Wolframbestimmung mit Thioglykolsäure in wäßriger Lösung erreicht eine Bestimmungsgrenze von $$\underline c $$ = 0,92 ppm W (P=99,9%;M=2) und eine Standardabweichung vons=0,24 ppm W (f=21).
    Notes: Summary W(VI) forms moderately stable, five-membered ring chelates of the composition WR2 with thioglycolic and glycolic acid, and a very weak WR with glycine. Chelation with the six-ring forming 3-mercaptopropionic acid and o-mercaptobenzoic acid could not be detected. The chelate with thioglycolic acid crystallizes from methanol as the yellow sodium salt WO2(SCH2COONa)2·2CH3OH and can be extracted into butanol as an ion pair with diphenylguanidine. The photometric determination of tungsten with thioglycolic acid has a determination limit of $$\underline c $$ = 0.92 ppm W (P=99.9%;M=2) and a standard deviations=0.24 ppmW (f=21).
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 122-124 
    ISSN: 1618-2650
    Keywords: Best. von Sulfat in Umweltmaterial ; Wasser ; Spektralphotometrie ; Durchflußsystem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary Sulphate in various environmental samples was determined by measuring the optical absorbance upon reaction with the barium(II) dimethylsulphonazo(III) complex. The measurement took place in a flow-through system. Interferences from phosphate, metal ions and others were eliminated. The results of a turbidimetric measurement, a spectrophotometric measurement with thorin, an automatic titration and the proposed method are compared. The latter allows the determination of sulphate in the range of 1.4–60 μmol·l−1. The standard deviation is 0.3–0.6 μmol·l−1, depending on the type of sample (water) analysed. A determination takes 1.5min.
    Notes: Zusammenfassung Sulfat wurde in verschiedenen Umweltproben durch Messung der Extinktion nach Reaktion mit dem Barium(II)-dimethylsulfonazo(III)-komplex im Durchflußsystem bestimmt. Störungen von Phosphat, Metallionen, u.a. wurden beseitigt. Die Ergebnisse einer turbidimetrischen, einer photometrischen, einer automatischen Titration und der vorgeschlagenen Methode werden verglichen. Die Methode ermöglicht die Sulfatbestimmung im Bereich von 1,4–60 μmol·l−1. Die Standardabweichung beträgt 0,3–0,6 μmol· l−1 je nach Typ des Probematerials (Wasser). Eine Bestimmung erfordert 1,5min.
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 271-271 
    ISSN: 1618-2650
    Keywords: Best. von Blei in Wasser, Abwasser, Staub ; Spektralphotometrie ; Dithizon
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 413-413 
    ISSN: 1618-2650
    Keywords: Best. von Platin(IV) mit Chlorpromazin ; Spektralphotometrie
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    Fresenius' Zeitschrift für analytische Chemie 297 (1979), S. 419-419 
    ISSN: 1618-2650
    Keywords: Spektralphotometrie ; Bouguer-Lambert-Beersches Gesetz, neues Konzept
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    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 160-160 
    ISSN: 1618-2650
    Keywords: Best. von Phenothiazinen ; Spektralphotometrie ; Silicowolframsäure
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 43-44 
    ISSN: 1618-2650
    Keywords: Best. von Salicylaldehyd ; Spektralphotometrie ; konz. Schwefelsäure
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  • 56
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 46-46 
    ISSN: 1618-2650
    Keywords: Best. von Osmium mit N-Benzoyl-o-tolylhydroxylamin ; Spektralphotometrie
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    Topics: Chemistry and Pharmacology
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  • 57
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 415-416 
    ISSN: 1618-2650
    Keywords: Best. von Albumin in Serum ; Spektralphotometrie ; Isothiocyanatodioxo-tolyldihydro-benzisochinolin, Rinderserum
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    Topics: Chemistry and Pharmacology
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  • 58
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    Fresenius' Zeitschrift für analytische Chemie 299 (1979), S. 128-128 
    ISSN: 1618-2650
    Keywords: Best. von Ruthenium mit 2-Methyl-1,4-naphtochinon-monoxim ; Spektralphotometrie ; Extraktion
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  • 59
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 412-413 
    ISSN: 1618-2650
    Keywords: Best. von Palladium(II), Ruthenium(III) mit Isonitrosobenzoylacetone ; Spektralphotometrie
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  • 60
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    Fresenius' Zeitschrift für analytische Chemie 297 (1979), S. 384-387 
    ISSN: 1618-2650
    Keywords: Best. von Uran ; Spektralphotometrie ; Spuren, Extraktion mit Triphenylarsinoxid in Chloroform
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    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wurde eine einfache, vielseitig anwendbare spektralphotometrische Uranbestimmung für U6+-Mengen bis in den ng-Bereich ausgearbeitet, bei der über 60 Kationen und etwa 20 Anionen in weiten Grenzen nicht stören. Das mit Triphenylarsinoxid in CHCl3 aus der zu untersuchenden Lösung extrahierte Uran wird mit oxalsäurehaltiger 5,5 M HClO4 zurückextrahiert und in den Arsenazo III-Komplex überführt. Die mit diesem Schritt verbundene Aufkonzentrierung erlaubt noch bis zu 0,01 μg Uran in 200 ml Ausgangslösung spektralphotometrisch bei 655 nm zu bestimmen. Im günstigsten Arbeitsbereich beträgt die relative Standardabweichung ±1%. 4 Probelösungen können in 1 h analysiert werden.
    Notes: Summary A simple and versatile spectrophotometric method for the determination of uranium down to the μg range was worked out. About 60 cations and 20 anions were found not to cause interferences in a wide concentration range. U6+ is extracted with triphenylarsine oxide in chloroform, back-extracted with 5.5 M perchloric acid containing oxalic acid and converted to the arsenazo III-complex. The concentration step involved allows the spectrophotometric determination of 0.01 μg of uranium in 200 ml of original solution at 655 nm. A standard deviation of ±1 % can be achieved and it is possible to analyse about 4 solutions per hour.
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    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 156-157 
    ISSN: 1618-2650
    Keywords: Best. von Sulfat in Wasser ; Spektralphotometrie ; Ionenaustausch, Dimethylsulfonazo(III)
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  • 62
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    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 150-154 
    ISSN: 1618-2650
    Keywords: Best. von Kupfer mit Fluoronen ; Spektralphotometrie ; Übersicht über die Fluorone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Fluorone, Verbindungen des 2,3,7-Trihydroxyisoxanthenons-(6), eignen sich als empfindliche Reagentien für die spektralphotometrische Analyse zahlreicher Metallionen im sichtbaren Teil des Spektrums. Neben einigen grundsätzlichen Anmerkungen zur Herstellung, zu den Eigenschaften und Reaktionen der Fluorone mit Metallionen wird die Verwendung des Cyclohexylfluorons (CHF) für die photometrische Bestimmung von Cu(II)-Ion beschrieben; hierbei ergibt sich ein molarer Extinktionskoeffizient von 191000 l/Mol · cm und eine Standardabweichung von ±0,2 ng/ml. Der Anwendungsbereich liegt bei 6–60 ng Cu/ml. Bi, Fe(II/III) und Sb müssen zuvor abgetrennt werden.
    Notes: Summary Fluorones, derivates of 2,3,7-trihydroxyisoxanthenone-(6), are sensitive reagents for the spectrophotometric determination of many metal ions in aqueous solution. Besides some principal remarks on the synthesis, properties and reactions of fluorones, the application of cyclohexylfluorone for the determination of Cu(II) ion is described in detail. This method is applicable in the concentration range 6–60 ng of Cu/ml. The molar absorptivity is 1910001/Mol · cm and the standard deviation is ±0.2 ng/ml. Bi, Fe(II, III) and Sb have to be separated prior to the determination.
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  • 63
    ISSN: 1432-2048
    Keywords: Bryophyllum ; Circadian rhythm ; CO2 output ; Phytochrome ; Red light ; Rhythm (circadian)
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    Topics: Biology
    Notes: Abstract The rhythm of carbon dioxide output in Bryophyllum leaves was entrained on exposure to 0.25 h of white light every 24 h. Entrainment also occurred on similar exposure to monochromatic radiation in spectral bands centred at 660 nm and, to a lesser extent, at 730 nm, but a band centred at 450 nm was without effect. A “skeleton” irradiation programme comprising two 0.25-h exposures to white light per 24 h also entrained the rhythm when the intervening dark periods were either 7.5 h and 16 h, or 10.5 h and 13 h. The rhythm disappeared when the two exposures were separated by 11.5-h and 12-h dark periods. Regular 0.25-h exposures to red light separated by 11.75-h periods of darkness also resulted in loss of the rhythm. Red/far-red reversibility was observed in irradiation schedules having either one or two exposures to red light daily. In the latter case, far-red reversal of the effects of one of the exposures to red light resulted in entrainment of the rhythm by the other, instead of abolition of the rhythm. The occurrence of distinct red/far-red reversibility suggests strongly that phytochrome is the pigment involved in entrainment of this rhythm by cycles of light and darkness.
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  • 64
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    Planta 138 (1978), S. 25-28 
    ISSN: 1432-2048
    Keywords: Action spectrum ; Chlorophyll ; Phaseolus ; Photomorphogenesis ; Phytochrome
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    Topics: Biology
    Notes: Abstract Red light absorption by photosynthetic pigments screens stem tissue of Phaseolus vulgaris L. seedlings to such an extent that the most effective wavelength for the phytochrome induction control of stem growth is approximately 628 nm. Screening is greater in the first internode than in the hypocotyl. The consequences are that, compared with etiolated seedlings, much higher irradiances are required for phytochrome control in green plants, and the efficiency of 660 nm light is markedly reduced. Even very high exposures at 660 nm may not achieve appreciable photoconversion of P r to P fr.
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  • 65
    ISSN: 1432-2048
    Keywords: Adiantum ; Blue-light effect ; Cell division ; Light, microbeam ; Photomorphogenesis ; Phytochrome
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    Topics: Biology
    Notes: Abstract Protonemata of the fern Adiantum capillusveneris L., grown as single-cell filaments under continuous red light, were irradiated with a narrow beam of blue light. Only irradiation of the region containing the nucleus induced cell division. Beams of 30 μm in width, which corresponds to the diameter of the nucleus, or wider, were equally effective; beams 10 μm wide or less were less effective. The results indicate that the nuclear region is the site of the blue- and near ultraviolet-light-absorbing pigment (PB-NUV) which mediates the timing effect of cell division. In contrast, the effect of a narrow beam of far-red (FR) light, which delays the onset of the blue-light-induced cell division, was found to be present along the entire length of the protonema cell, including the largely vacuolated basal region of the latter. Polarized FR light having the electrical vector parallel to the protonema axis was less effective than that vibrating in other directions. These observations support the hypothesis that the phytochrome controlling the timing effect is localized in the plasma membrane.
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  • 66
    ISSN: 1432-2048
    Keywords: Lemna ; Membrane potential ; Phytochrome
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    Topics: Biology
    Notes: Abstract Light-stimulated transmembrane potential changes have been measured continuously after implantation of microelectrodes into subepidermal cells of the short-day plant Lemna paucicostata 6746. Irradiation for 5 min with white or red light caused a transient hyperpolarization. These potential changes could be suppressed with 10-6 M DCMU. Irradiation of DCMU-inhibited plants with far-red light for 5 min hyperpolarized the membrane potential, which thereafter was not changed by further far-red application. Consecutive red light irradiation for 5 min depolarized the membrane potential. The red/far-red reversibility of the potential changes (which could be repeated several times with a single plant) suggests the participation of phytochrome.
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  • 67
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    Planta 141 (1978), S. 1-7 
    ISSN: 1432-2048
    Keywords: Flowering ; Pharbitis ; Photomorphogenesis ; Photoperiodic induction ; Phytochrome
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    Topics: Biology
    Notes: Abstract For dark-grown seedlings of Pharbitis nil capacity to flower in response to a single inductive dark period was established by 24 h white, far-red (FR) or ruby-red (BCJ) light and by a skeleton photoperiod of 10 min red (R)-24 h dark-10 min R. FR alone was ineffective without a brief terminal (R) irradiation, confirming that the form of phytochrome immediately prior to darkness is a crucial factor for flowering in Pharbitis. The magnitude of the flowering response was significantly greater after 24 h FR or white light (WL) (at 18° C and 27° C) than after two brief skeleton R irradiations, but the increased flowering response was not attributable to photosynthetic CO2 uptake because this could not be detected in seedlings exposed to 24 h WL at 18° C. Photophosphorylation could have contributed to the increased flowering response as photosystem I fluorescence was detectable in plants exposed to FR, BCJ, or WL, but there were large differences between flowering response and photosystem I capacity as indicated by fluorescence. We conclude that phytochrome plays a major role in photoresponses regulating flowering. There was no simple correlation between developmental changes, such as cotyledon expansion and chlorophyll formation during the 24-h irradiation period, and the capacity to flower in response to a following inductive dark period. Changes in plastid ultrastructure were considerable in light from fluorescent lamps and there was complete breakdown of the prolamellar body with or without lamellar stacking at 27 or 18° C, respectively, but plastid reorganization was minimal in FR-irradiated seedlings.
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  • 68
    ISSN: 1432-2048
    Keywords: Hordeum ; Membranes ; Organelles ; Phytochrome
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    Topics: Biology
    Notes: Abstract Red light treatment in vitro increases the pelletability of phytochrome in homogenates of etiolated barley (Hordeum vulgare L. cv. ‘Julia’) leaves. When mixtures of soluble phytochrome (100,000 x g supernatant) and partially-purified organelles (Sephadex G-50 eluate) are irradiated the amount of pelletable phytochrome increases by a factor of two. Pre-irradiation treatments show that phytochrome in both components of the mixture must be in the Pfr form for increased pelletability to be observed. Once associated, photoreversion of Pfr to Pr does not result in decreased pelletability. The results are consistent with a non-artifactual in vitro association of soluble phytochrome to organelle membranes. One possible explanation is that Pfr molecules associate to form dimers.
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  • 69
    ISSN: 1432-2048
    Keywords: Avena ; Immunocytochemistry ; Phytochrome
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    Topics: Biology
    Notes: Abstract Phytochrome of oat (Avena sativa L., cv. Garry) coleoptile cells in the red-light-absorbing form, Pr, is diffusely distributed while after conversion to the far-red-light-absorbing form, Pfr, it is observed only in very small areas within the cell. Comparison of phytochrome photoversibility measurements to the distribution of the pigment within the cell indicates that the spectral assay is not influenced by the observed compartmentalization of the chromoprotein. However, the observed compartmentalization of phytochrome is correlated with a loss in spectrophotometrically detectable Pr.
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  • 70
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    Planta 141 (1978), S. 211-216 
    ISSN: 1432-2048
    Keywords: Hypocotyl growth ; Photomorphogenesis ; Phytochrome ; Sinapis
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    Topics: Biology
    Notes: Abstract After sowing, mustard (Sinapis alba L.) seedlings were grown for 48 h in white light (25°C). These fully de-etiolated, green seedlings were used as experimental material between 48 and 72 (84) h after sowing. The question researched was to what extent control by light of hypocotyl elongation is due to phytochrome in these seedlings. It was found that the light effect on hypocotyl growth is very probably exerted through phytochrome only. In particular, we found no indication for the involvement of a specific blue light photoreceptor pigment.
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  • 71
    ISSN: 1432-2048
    Keywords: Avena ; Etioplasts ; Mitochondria ; Phytochrome
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    Topics: Biology
    Notes: Abstract Phytochrome was determined in etiolated laminae of Avena sativaL. either without pretreatment or after 5 min of red irradiation followed by different periods of darkness (0–24 h). At given intervals laminae were homogenized and phytochrome was determined spectrophotometrically in the total homogenate and in purified etioplasts and mitochondria. Enhanced specific activity of phytochrome was found in all fractions after the irradiation in comparison to dark controls. Phytochrome destruction was observed in all fractions at the beginning of the subsequent dark period. Whereas the homogenate and the mitochondrial fraction showed a continuous destruction so that phytochrome reached a level far below that in etiolated plants, the phytochrome level in the plastid fraction reacheda minimum at 2 h with a subsequent increase beyond the dark level. This increase was most pronounced between 4 and 8 h after the red irradiation. The results are discussed in terms of the destruction and possible de novo synthesis of phytochrome that may be different in mitochondria and plastids.
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  • 72
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    Planta 144 (1978), S. 1-5 
    ISSN: 1432-2048
    Keywords: Germination (seeds) ; Lactuca ; Phytochrome ; Seed germination
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    Topics: Biology
    Notes: Abstract Germination of certain dry “seeds” (achenes) of Lactuca sativa L. cv. Grand Rapids was increased to ca. 75% after irradiation with 665 nm red light (R; 1x103 J m-2); this response was eliminated by far-red light (FR) following the R. The response of dry seeds required an order of magnitude more light than that of wetted seeds, and was not maximal until 48 h after irradiation. Other seeds, which could not be stimulated by R in dry state, showed a partial response after 10 min hydration. Irradiation of dry seeds (or seeds wetted 1 h) with FR (1x103 J m-2) reduced dark germination from 26% to 2%. Seeds dehydrated in an oven (60°C, 90 min) showed a decrease in germination if irradiated with R (1x105 J m-2) before wetting. The results show that phytochrome is present in dry lettuce seeds (and functional in some seed lots) prior to wetting; and that in other seed lots the molecule becomes functional within minutes after wetting the seeds. Transformation of the FR absorbing from of phytochrome (PFR) to the inactive from (PR) occurs at lower seed moisture content than the reverse reaction. It appears that dormancy in seeds ripened in sunlight might be assured during seed drying and maturation by the more effective transformation of PFR to PR than vice versa as phytochrome is dehydrated.
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  • 73
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    Planta 143 (1978), S. 309-313 
    ISSN: 1432-2048
    Keywords: Avena ; Light-grown tissue ; Phytochrome ; San 9789
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    Topics: Biology
    Notes: Abstract Phytochrome was studied spectrophotometrically in Avena sativa L. seedlings that had been grown for 6 d in continous white fluorescent light from lamps. Greening was prevented through the use of the herbicide San 9789. When placed in the light, phytochrome (Ptot) decreased with first order kinetics (τ1/2 ≈ 2 h) but reached a stable low level (≈2.5% of the dark level) after 36 h. This concentration of phytochrome remained constant in the light and during the initial hours of a subsequent dark period, but increased significantly after a prolonged dark period. Evidence suggests that the constant pool of phytochrome in the light is achieved through an equilibrium between synthesis of the red absorbing (Pr) and destruction of the far-red absorbing form (Pfr) of phytochrome. It is concluded that the phytochrome system in light-grown oat seedlings is qualitatively the same as that known from etiolated monocotyledonous seedlings, but different than that described for cauliflower florets.
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  • 74
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    Planta 143 (1978), S. 323-328 
    ISSN: 1432-2048
    Keywords: Bryophyllum ; Circadian rhythm ; Photocontrol ; Phytochrome
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    Topics: Biology
    Notes: Abstract A 4-h exposure to white light from fluorescent lamps can shift the phase of the rhythm of CO2 output in leaves of Bryophyllum fedtschenkoi Hamet & Perr. otherwise kept in continuous darkness. The position in the cycle at which irradiation occurs determines the magnitude and direction of the phase shift. Red and white light induce similar advances or delays in the phase, but blue and far-red irradiation have no effect. Far-red irradiation given simultaneously with, or immediately after, exposure to red light, modifies the phase-shift induced by red light alone. Radiation in the red and far-red regions of the spectrum interacted in several experimental régimes, but complete red/far-red reversibility was not observed. The evidence suggests that phytochrome is the receptor molecule involved in the induction of phase-shifts by light.
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  • 75
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    Planta 143 (1978), S. 233-239 
    ISSN: 1432-2048
    Keywords: Adaptation (chromatic) ; Chromatic adaptation ; Cyanophyta (cyanobacteria) ; Phycobiliproteins ; Phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Action spectra for chromatic adaptation in Fremyella diplosiphon Drouet have been determined using techniques previously described. Action maxima are at 540 nm, with a half-band width of 80 nm, for induction of phycoerythrin synthesis (green action) and at 650 nm, with a half-band width of 90 nm, for reversal of induction of phycoerythrin synthesis (red action). The red-action spectrum includes a secondary action band centered at ca. 360 nm. Red and green action overlap from 570 to 590 nm with an isosbestic point in the vicinity of 580 nm. Shoulders are present at 520 and 630 nm. Red light is more active than green light. The 540:650-nm quantum effectiveness ratio is 1:7. There is relatively little action of either kind in the blue. The 387:540 nm and 460:650-nm quantum effectiveness ratios are zero. These results contrast strongly with previous determinations in the same organism, with major activity indicated in the blue; they are consistent with the control of photomorphogenesis in the Cyanophyta by a master pigment, analogous to phytochrome.
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  • 76
    ISSN: 1432-2048
    Keywords: Flowering ; Pharbitis ; Photoperiodic induction ; Phytochrome ; Spectrophotometry (phytochrome)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The low chlorophyll content of cotyledons of Pharbitis nil grown for 24 h in far-red light (FR) or at 18° C in white light from fluorescent lamps (WL) allows spectrophotometric measurement of phytochrome in these tissues. The Δ(ΔA) measurements utilize measuring beams at 730/802 nm and an actinic irradiation in excess of 90 s. The constancy of the relationship between phytochrome content and sample thickness confirms that, under these conditions of measurement, a true maximum phytochrome signal was obtained. These techniques have been used to follow changes in the form and amount of phytochrome during an inductive dark period for flowering. Following exposure to 24h WL at 18° C with a terminal 10 min red (R), Pfr was lost rapidly in darkness and approached zero in less than 1 h; during this period there was no change in the total phytochrome signal. Following exposure to 24 h FR with a terminal 10 min R, Pfr approached zero in 3 h, and the total phytochrome signal decreased by about half. The relevance of these changes to photoperiodic time measurement is discussed.
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  • 77
    ISSN: 1432-2048
    Keywords: Flowering ; Pharbitis ; Photoperiodic induction ; Phytochrome ; Spectrophotometry (phytochrome)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During an inductive dark period for flowering, changes in phytochrome have been followed in cotyledons of Pharbitis nil seedlings using a spectrophotometric and a physiological technique. There was agreement between the two techniques, both indicating a rapid lowering of the levels of the far-red-absorbing form of the pigment (Pfr) during the first 30–90 min of darkness. Thus, Pfr could provide the cue which signals the beginning of darkness and the length of the critical dark period was, in some instances, correlated with the time of Pfr disappearance. However, there was no correlation with another indicator of photoperiodic time measurement, the time in darkness at which a brief night interruption becomes inhibitory to flowering. These results imply that the transition from light to darkness is not signalled by the disappearance of Pfr. However, the involvement of other photoreceptors seems unlikely. Thus, some mode of phytochrome action other than a simple Pfr-mediated response may be involved in the light/dark-sensing reactions of photoperiodism
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  • 78
    ISSN: 1432-2048
    Keywords: Chlorophyll ; Chloroplasts ; Grana ; Phytochrome ; Sinapis ; Thylakoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The etioplast»chloroplast transition in the cotyledons of mustard seedlings (Sinapis alba L.) has been studied by electron microscopy. It was found that the active form of phytochrome, established by a red light pulse pretreatment, increases the initial rate and eliminates the lag of grana and stroma thylakoid formation after the onset of white light 60 h after sowing. The effect of a pretreatment with 15 s red light pulses is fully reversible by 756 nm light pulses. This reversibility is lost within 5 min. Evidence is presented which suggests that the time course of grana and stroma thylakoid formation is not correlated with the time course of the dispersal of the prolamellar body. The different functions of phytochrome and chlorophyll in controlling thylakoid formation are discussed.
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  • 79
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    Planta 142 (1978), S. 119-122 
    ISSN: 1432-2048
    Keywords: Chlorophyll ; Ethylene ; Phenylalanine ammonia-lyase ; Phytochrome ; Sinapis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The concept (Burg, 1973) that ethylene mediates the action of phytochrome in seedling photomorphogenesis was tested in the intact mustard (Sinapis alba L.) seedling. The effect of exogenous ethylene (100 μl l−1) on five distinct, phytochrome-mediated photoresponses of the cotyledons was investigated. It was found that anthocyanin contents (see Bühler et al., 1978) and phenylalanine ammonia-lyase levels (EC 4.3.1.5) are strongly reduced by ethylene while the capacity of chlorophyll synthesis is considerably enhanced. Levels of glutathione reductase (EC 1.6.4.2) and pools of photoconvertible protochlorophyll(ide) are unaffected by ethylene. It is concluded that these findings are incompatible with the idea that ethylene plays the role of a mediator in phytochrome-induced photomorphogenesis.
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  • 80
    ISSN: 1432-2048
    Keywords: Chenopodium ; Far-red ; Photoequilibrium ; Phytochrome ; Stem extension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chenopodium album seedlings were grown in light environments in which supplementary far-red light was mixed with white fluorescent light during various parts of the photoperiod. Both the logarithmic rate constant of stem extension and the leaf dry weight: stem dry weight ratio were linearly related to estimated phytochrome photoequilibrium (ϕ) in each treatment regime. These data are taken to be indicative of a functional link between phytochrome and development in the green plant. A layer of chlorophyllous tissue only affected the linearity between calculated ϕ and the logarithmic stem extension rate at high chlorophyll concentrations, whilst even low concentrations-equivalent to the levels found in stem tissue-caused a significant shift in measured ϕ. End-of-day supplementary far-red (FR) light induced between 0–35 per cent of the response elicited by all-day supplementary FR, whilst daytime supplementary FR (with a white fluorescent light end-of-day treatment) induced approximately 90 per cent. The ecological significance of this difference is discussed with respect to shade detection.
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  • 81
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    Planta 143 (1978), S. 109-111 
    ISSN: 1432-2048
    Keywords: Boron ; Fluorescein ; Gravity ; Phytochrome ; Vigna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hypocotyl sections from dark-grown mung bean (Vigna radiata (L.) Wilczek) seedlings grown without boron exhibit little or no increase in the translocation of fluorescein in phloem cells following gravitational stimulation or red irradiation. In contrast, pretreatment of the hypocotyl sections with low concentrations of boric acid before red irradiation or gravitational stimulation results in a rapid increase in fluorescein movement. Mung bean root tips without boron fail to remain attached to a negativelycharged glass surface after several minutes of red irradiation. A low boron concentration in the solution induces tip attachment. The suggestion is made that boron is required to stabilize a positive electrostatic charge in the plasma membrane that is generated by the actions of phytochrome and gravity.
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  • 82
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    Planta 141 (1978), S. 311-314 
    ISSN: 1432-2048
    Keywords: Abscission resistance ; Malformin ; Phaseolus ; Phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The active portion of the visible spectrum which is required for malformin to produce leaves which are resistant to dark abscission from cuttings of Phaseolus aureus is red light. Abscission resistance was partially to almost completely lost by far irradiation prior to dark incubation. Although Ethrel, an ethylene releasing compound, stimulated dark abscission of resistant and control leaves, resistance was not lost because control leaves always abscised at a greater rate. The participation of phytochrome in the induction of abscission resistance by malformin is indicated.
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  • 83
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    Planta 142 (1978), S. 109-117 
    ISSN: 1432-2048
    Keywords: Anthocyanin synthesis ; Ethylene ; Phytochrome ; Sinapis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The etiolating, intact mustard (Sinapis alba L.) seedling exhibits a distinct temporal pattern of ethylene production. Light, operating through phytochrome, increases the rate of ethylene production without changing the pattern. Ethylene production of the isolated plant parts (segments), added together, exceed the production of the intact system even if the wound effect is taken into account. There is no significant light effect on ethylene production of the segments. Phytochrome-mediated anthocyanin synthesis in the cotyledons is inhibited by ethylene. The responsiveness towards ethylene of the anthocyanin producing metabolic chain is decreased by phytochrome. As anthocyanin synthesis is only partly inhibited under saturating ethylene concentrations in the atmosphere around the seedlings (100 μl l−1), a twofactor analysis becomes feasible. This analysis leads to the result that phytochrome and ethylene show multiplicative behavior, meaning that phytochrome and ethylene act on the same metabolic sequence (leading to anthocyanin) but independently of each other, and at different sites. Therefore, the hypothesis that ethylene mediates the action of phytochrome in anthocyanin synthesis and photomorphogenesis in general appears to be inapplicable.
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    Planta 142 (1978), S. 225-228 
    ISSN: 1432-2048
    Keywords: Hordeum ; Phytochrome ; Receptor site
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The absorption maximum of the far-red absorbing form of phytochrome in the difference spectrum for phototransformation (Pfr λmax) was investigated in vivo and in in vitro pellets from dark grown Hordeum vulgare L. primary leaves. Exposure of pellets in Honda medium from tissue pre-irradiated with red light to far red light gave a Pfr λmax of 734 nm, a slightly longer wavelength than was seen in vivo (730 nm). After incubation as the red absorbing form of phytochrome (Pr) for 2 h at 0° C irradiation with red light showed that Pfr λmax had shifted to shorter wavelength (716 nm) in Honda medium. Further incubation as Pfr for 2 h at 0° C and irradiation with far red light showed that Pfr λmax had shifted to longer wavelength (726 nm). Similar shifts were also seen in other media, although the peak positions were different. Phytochrome remained pelletable throughout these experiments and Pfr λmax is compared to that of soluble phytochrome in similar media. The results are interpreted as indicating changes in molecular environment of the putative phytochrome membrane receptor site and that Pfr λmax can be used to probe the nature of this binding.
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  • 85
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    Oxidation of metals 12 (1978), S. 227-245 
    ISSN: 1573-4889
    Keywords: oxidation ; sulfidation ; iron-chromium-nickel alloy ; thermochemical diagram ; parabolic rate constant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Oxidation-sulfidation studies of Fe-Cr-8Ni alloys with 4, 12, and 22 wt. % Cr were conducted at 750 and 875°C in multicomponent gas mixtures that contained CO, CO2, CH4, H2, and H2S. The reaction processes resulted in parabolic kinetics. A chromium concentration in the range 0–12 wt. % in the alloy had a negligible effect on the parabolic rate constant; however, the rate constant for the alloy with 22 wt. % Cr was significantly lower. For a given sulfur partial pressure, the oxygen partial pressures required for the formation of a continuous oxide layer in an Fe-22Cr-8Ni alloy were ∼102 to 103 times those calculated for Cr-Cr2O3 equilibrium at temperatures of 875 and 750° C, respectively.
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  • 86
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    Oxidation of metals 12 (1978), S. 451-471 
    ISSN: 1573-4889
    Keywords: HCl gas ; H2O vapor ; Ni-Cr-Al alloy ; oxidation ; hot corrosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Moist air containing HCl gas caused the oxide formed on a Ni-Cr-Al alloy at 850°C to crack during the early stages of growth, and extensive blistering and spalling occurred on cooling. In dry air containing HCl gas no oxide cracking was observed at temperature although the oxide blistered and spalled on cooling. In dry or moist air free from HCl an adherent protective oxide formed which did not spall on cooling. The oxide cracking at temperature has been attributed to the production of hydrogen by reaction of Cr and Al in the alloy with water vapor and the removal of NiO as NiCl2 by reaction with HCl gas. Hydrogen produced by reaction of water vapor or HCl with Cr or Al dissolved in the alloy at temperature, but on cooling the hydrogen was released, causing the oxide to blister and spall. Preoxidation of the alloy in HCl-free atmospheres eliminated these effects of HCl gas in short-term isothermal tests.
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  • 87
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    Oxidation of metals 12 (1978), S. 1-22 
    ISSN: 1573-4889
    Keywords: NaCl vapor ; Ni-Cr-Al alloy ; oxidation ; hot-salt corrosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A thin protective oxide formed on a Ni-19.7 Cr-2.4 Al alloy in air at 850°C. Microstructural examination of stripped films showed that the oxide was duplex with an inner chromium-rich layer of NiCr2O4 + Cr2O3 with probably some NiAl2O4 + Al2O3, and an outer nickel-rich layer, principally NiO. The oxide grew faster in the presence of NaCl and it differed significantly in microstructure and composition from a very early stage. The thicker regions of the oxide assumed regular polyhedral shapes in air + NaCl, rather than the irregular nodular shape exhibited in clean air, as well as becoming richer in chromium. The results suggest that chloride vapor increases cationic mobility in the oxide. It is proposed that Cl− ions are incorporated in the oxygen close-packed lattice, thereby increasing ionic mobility in Cr2O3.
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  • 88
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    Oxidation of metals 12 (1978), S. 83-110 
    ISSN: 1573-4889
    Keywords: oxidation ; iron ; chromium ; Fe-9% Cr alloy ; Auger electron spectroscopy
    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 or general corrosion behavior of metals at pressures of 1 atm or more is usually investigated by oxidizing samples under prescribed conditions and then subsequently characterizing the surface produced using one or more of the experimental methods available. This article describes a method which obviates the necessity of transferring samples from the oxidizing environment to the instrument for analysis, is nondestructive, and monitors the oxidizing surface in situ. The oxidation of iron, chromium, and a 9% chromium-iron alloy in carbon dioxide at atmospheric pressure and at 773°K is described. The surfaces of these materials were analyzed by Auger electron spectroscopy during exposure to the gas. Spectra and diagrams illustrating the variation in surface composition as oxidation proceeded are shown and possible mechanisms for the oxidation reactions are briefly discussed. The formation of the surface oxide on iron and on the 9% Cr-Fe alloy appears to follow very similar paths under the conditions of oxidation used. In all the materials studied trace impurities such as sulfur participated in the oxidation reactions.
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  • 89
    ISSN: 1573-4889
    Keywords: Cu-Si alloys ; oxidation ; kinetics ; silica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of Cu-Si alloys (containing up to 4.75 wt. % Si) in $${\text{p}}_{O_2 } $$ =0.01 atm from 800 to 1000°C has been investigated using thermogravimetry and other techniques. A 0.04% Si alloy followed a parabolic oxidation law with a rate similar to that of pure Cu. As the Si concentration increased the rate decreased and became irregular owing to SiO2 particles or flakes at the alloy-scale interface. It is considered that sintering of SiO2 particles and rupture of the sinter because of contraction during sintering are responsible for the irregular kinetics. A SiO2 layer forms directly on the 4.75% Si alloy which oxidizes uniformly. The SiO2 was always amorphous. In pure CO2 a similar pattern of amorphous SiO2 particles, flakes, and layers occurs.
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    Oxidation of metals 12 (1978), S. 215-225 
    ISSN: 1573-4889
    Keywords: oxidation ; Fe-Ni alloys ; kinetics ; scale morphology ; EPMA
    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—19.34 wt. % Ni alloy in dry CO2 has been studied at 700—1000°C using thermogravimetry, metallography, and EPMA. Weight gains for oxygen consumption followed a linear-parabolic-linear sequence at all temperatures. During the initial linear stage the scale consisted mainly of magnetite and the activation energy of 133±25 kJ · mole−1 is considered to be due to dissociation of CO2 into CO and adsorbed oxygen on the outer magnetite surface. During the parabolic oxidation stage a continuous Ni-rich layer containing ∼ 70% Ni forms a barrier to the diffusion which has an activation energy of 192±79 kJ · mole−1. The breakdown of the barrier layer causes a return to linear kinetics with an activation energy of 138±42 kJ · mole−1 for dissociation of CO2 on the outer surface. During the final linear stage there is pronounced general and intergranular subscale formation. Detailed information is presented of the Ni redistribution and concentrations during oxidation and its correlation with the kinetics and morphology.
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  • 91
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    Oxidation of metals 12 (1978), S. 35-66 
    ISSN: 1573-4889
    Keywords: CoCrAl ; oxidation ; oxide scale adherence ; rare-earth effect ; hafnium ; yttrium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effect of small amounts of yttrium (up to 1 wt. %) and hafnium (up to 1.5 wt.%) on the oxidation behavior of Co-Cr-Al alloys in the temperature range 1000–1200°C for times up to 1000 hr in air has been studied. The major portion of the study has been concerned with Co-10Cr-11Al base alloys. Both isothermal and cyclic tests have been carried out; the cycle used consisted of 20 hr at temperature, followed by cooling to room temperature. Both additions reduce the overall oxidation, Hf somewhat more so than Y. In part, this is due to the improved adhesion between scale and alloy reducing scale spallation at temperature, and in part due to possible modification of the Al2O3 grain size. The former factor is far more critical under thermal cycling conditions. Under isothermal conditions the oxidation rate increases with increasing Hf content with all but the 1.5 wt.% alloy oxidizing more slowly than the Hf-free alloy; increase in Y content has the reverse effect. Under thermal cycling conditions the 0.3 and 1.0 wt.% Hf alloys show the lowest overall weight gain. Metallographic evidence suggests that the improved scale adhesion is due principally to a pegging mechanism; the active elements promote the growth of intrusions of Al2O3 into the alloy. However, if the intrusions are too large, they can act as initiators of scale failure.
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    Oxidation of metals 12 (1978), S. 139-156 
    ISSN: 1573-4889
    Keywords: Rosenburg method ; oxidation ; CoO
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The Rosenburg continuous kinetic method is proposed for the determination of the parabolic rate constants of metal oxidation as a function of temperature and oxidant pressure. Using this method, it is possible to make numerous measurements in a continuous manner on a single metal sample left in situ in the furnace, thus eliminating systematic errors due to differences between samples. Moreover, using this method it is possible to determine directly from a given kinetic curve such important parameters as the coefficients of chemical diffusion and self-diffusion of the more mobile species in the studied compound and the total equilibrium defect concentration. The latter parameter has been inaccessible up to now by the experimental method. The limits of applicability of this method are given in the paper. As an example of this method, the kinetics of cobalt oxidation are investigated in the range of temperature 1000–1250°C and oxygen pressure 10−3−1 atm; the results compare favorably with those obtained by other authors. The method is, however, applicable to certain other systems, namely, metal oxides and sulfides.
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  • 93
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    Oxidation of metals 12 (1978), S. 173-181 
    ISSN: 1573-4889
    Keywords: oxidation ; hot corrosion ; sulfidation ; preoxidation ; scale penetration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The transport of sulfur through growing scales may occur by chemical (solution and diffusion) or physical (gas molecule permeation) mechanisms. Both possibilities are examined theoretically for the case of NiO growing on nickel. Experiments are designed and carried out to establish which mechanism plays the major role in sulfur transport. The results indicate that the physical mechanism is likely to be predominant.
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  • 94
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    Oxidation of metals 12 (1978), S. 23-34 
    ISSN: 1573-4889
    Keywords: cobalt ; oxidation ; sulfidation ; conjoint attack
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The attack of cobalt by sulfur and oygen simultaneously in Ar-SO2 atmospheres in the temperature range 500–900°C has been found to conform to the pattern established by the attack of other metals under similar conditions. A thermodynamic and kinetic interpretation of the mechanism has been proposed. The results also indicate that during the initial stages sulfur diffuses through the initially formed oxide layer, eventually leading to formation of the commonly observed duplex sulfide and oxide scale.
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  • 95
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    Oxidation of metals 12 (1978), S. 67-82 
    ISSN: 1573-4889
    Keywords: oxidation ; Fe-C ; kinetics ; oxide grain size ; grain-boundary diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Fe-C alloys containing 0.1, 0.5, and 1.0% C were oxidized in 1 atm O2 at 500°C. Two specimen preparations were used: annealed followed by slow cooling to form coarse pearlite plus proeutectoid ferrite or cementite; and cold-worked by abrading after annealing. The cold-worked alloys oxidize more rapidly. Annealed pearlite oxidizes faster than annealed ferrite. The differences in oxidation rate are caused by differences in the Fe3O4 grain size, that is, by the number of oxide grain boundaries available to act as easy diffusion paths for the outward diffusion of Fe through the Fe3O4. The oxidation rate constant is 10 times larger for fine-grained poly crystalline oxide than for oxide in which the Fe3O4 is monocrystalline.
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  • 96
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    Oxidation of metals 12 (1978), S. 503-526 
    ISSN: 1573-4889
    Keywords: nickel ; sulfur dioxide ; oxidation ; sulfidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The reaction of nickel with SO2 has been studied in the temperature range 650–1100°C at SO2 pressures from 10 to 760 Torr. Reaction kinetics have been studied by thermogravimetry; the reacted specimens have been characterized by means of metallography, scanning electron microscopy, and electron microprobe analysis. The reaction involves oxidation and sulfidation except at sufficiently high temperatures and low pressures of SO2 (e.g., 1000°C and 10 Torr SO2) where only formation of NiO takes place. Approximately linear reaction kinetics are observed between 650 and 900°C. Reaction mechanisms are discussed, and the relative importance of oxide formation and sulfidation is interpreted in terms of the thermodynamics of the Ni-O-S system.
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    Oxidation of metals 12 (1978), S. 247-256 
    ISSN: 1573-4889
    Keywords: oxidation ; iron ; magnetite ; oxide thickness ; electron back-scattering Mössbauer spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Magnetite films in the range 265–4520 Å have been grown on natural iron substrates and subsequently investigated by electron back-scattering Mössbauer spectroscopy. In particular, the percentage, P, of the total spectrum area contributed by the oxide has been determined as a function of oxide thickness, d. It was found that d up to ≈ 3000Å may be expressed (to an accuracy of ∼ 5%) by d (Å)=−1.95 × 103 ln (1–0.01 P). The experimental data have been compared with the theoretical predictions of both Huffman and Bainbridge. Good agreement between experiment and Huffman's predictions of P is obtained using values of the electron attenuation coefficient, μ, of 1.10 × 104 cm2 g−1 for the 7.3 keV electrons and 1.73 × 104 cm2 g−1 for the 5.4 keV electrons. A good fit of our data to Bainbridge's expression requires a somewhat lower effective μ, value of 0.8 × 104 cm2 g−1. The experimental P value for the thickest oxide (4520 Å) is lower than the theoretical predictions, probably as a result of a neglected mechanism recently identified by Tricker, Ash, and Cranshaw.
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    Oxidation of metals 12 (1978), S. 387-404 
    ISSN: 1573-4889
    Keywords: carburization ; oxidation ; austenitic Fe-Ni-Cr alloys ; internal carbide formation ; high-temperature corrosion and creep
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The carburization of NiCr 32 20 and NiCrSi 60 16 has been studied in CH4-H2 mixtures in the temperature range 900–1100°C. The methods included thermogravimetric measurements and studies on reacted specimens by X-ray diffraction, metallographic, and chemical analysis. Upon carburization internal carbides M7C3 and M23C6 are formed (M=mainly Cr); the rate of carburization is determined by carbon diffusion in the Fe-Ni matrix with carbide precipitations. The effect of the alloying elements Ni and Si on the carburization resistance of austenitic alloys is explained. By the same methods the oxidation and carburization in CO-H2O-H2 mixtures have been studied. The important role of a stable chromium oxide layer for the carburization resistance was confirmed. Creep tests at 1000°C in a CO-H2O-H2 atmosphere where Cr2O3 is stable showed carburization occurring through cracks in the oxide layer. At high strain rates premature failure occurs by carburization, which is followed by internal oxidation and formation of cracks, voids, and holes.
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    Fresenius' Zeitschrift für analytische Chemie 293 (1978), S. 416-416 
    ISSN: 1618-2650
    Keywords: Best von Vitamin D2 ; Spektralphotometrie ; HCl, Tetrachloräthan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    Fresenius' Zeitschrift für analytische Chemie 293 (1978), S. 416-416 
    ISSN: 1618-2650
    Keywords: Best. von Pikrinsäure ; Spektralphotometrie ; Zink und Ammoniumchlorid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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