ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Calcium  (24)
  • oxidation  (24)
  • Springer  (48)
  • 1980-1984  (30)
  • 1975-1979  (18)
Collection
Keywords
Publisher
  • Springer  (48)
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Rhythmic dentinogenesis in the rabbit incisor: Allometric aspects (1980)
    Springer
    Calcified tissue international 32 (1980), S. 45-53 
    Details
    ISSN: 1432-0827
    Keywords: Dentin ; Periodicity ; Allometry ; Calcium ; Sulfur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary We have described differences in the aspects of biological rhythms for calcium and sulfur deposition on the labial and lingual sides of the growing rabbit incisor, where growth occurs along a spiral axis. The calcium oscillations appear to be smoother on the labial side than on the lingual side. The lingual side is characterized by high-frequency rhythms with high amplitudes which possess the greatest percent of the power (Fourier analysis). These observations also reflect a difference in behavior of the mean Ca concentration across the labial and lingual sides. Sulfur rhythms on the labial side have higher amplitudes than those on the lingual side, but systematic differences in distribution of power between high and low frequencies is not as pronounced as in the case of Ca. The differences in Ca rhythms reflect differences in the growth rates of incisors on either side of the spiral axis. The labial side grows slightly faster than the lingual side, and its odontoblasts secrete Ca along the spiral axis and toward the pulp cavity at the same time. Thus the resultant direction of growth is more nearly opposite the extension of the occlusal end on the labial side, and Ca is consequently deposited over a wider area relative to that on the lingual surfaces. On the lingual side, Ca is deposited within a more limited area, and growth must therefore be continuous at high frequencies. The distribution of Ca on both sides of the tooth reflects these differences in growth rate and periodicity in two ways. First, given a unit area of tooth, the calcium concentration on the labial side is less than that of the lingual side. Second, whereas the calcium concentration on the labial side declines rapidly from the enamel-dentin junction to the pulp cavity, it is uniformly high across the lingual side because its growth is more continuous at high frequencies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02408520
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Rhythmic dentinogenesis in the rabbit incisor: Circadian, ultradian, and infradian periods (1980)
    Springer
    Calcified tissue international 32 (1980), S. 29-44 
    Details
    ISSN: 1432-0827
    Keywords: Rabbit ; Dentin ; Calcium ; Sulfur ; Periodicity ; Circadian ; Ultradian
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary We have identified a variety of biological rhythms involved in the apposition and mineralization of dentin in the rabbit incisor. Animals were injected during the day or night with lead acetate at 2-week intervals—to provide biological time markers in forming dentin—and transverse undecalcified sections of the lower incisors were prepared for electron microprobe analysis. The positions of the lead markers were identified, and the continuous distribution of calcium and sulfur was measured at 1 µm intervals between the markers. In thin sections stained with hematoxylin after decalcification, the widths of a series of structural increments (bands) were measured with an ocular micrometer. Fourier analysis of the data revealed spectra of structural and compositional rhythms with a range of periodicities which extended from a matter of hours [ultradian (〈24 h)] to days [infradian (〉24 h) and circadian (approximately 24 h)]. The structural and compositional rhythms appeared to be independent to the extent that they did not necessarily have the same periods, or amplitudes. Nor were there simple phase relationships between all of the rhythms. At some times, Ca and S fluctuations are inversely proportional (180° out of phase), but in other cases they are directly proportional or out of phase by varying degrees other than 180°. The analyses thus suggest that calcium and sulfur deposition (representing mineral and glycosaminoglycan deposition, respectively) are not simply inversely proportional, and that the hematoxylin-stained structural increments did not solely reflect differences in the distribution of the mineral components in dentin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02408519
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Role of kinetic effects on metal partition at the alloy-scale interface during the oxidation of alloys (1975)
    Springer
    Oxidation of metals 9 (1975), S. 215-223 
    Details
    ISSN: 1573-4889
    Keywords: cation diffusion ; oxidation ; metal partition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An alternative mass balance at the alloy-scale interface is proposed for the Wagner theory of binary alloy oxidation. A simple relation between the bulk composition of the alloy and the scale composition at the alloy-scale interface, ξ′, is derived in terms of the transport properties of the scale and the limit of application of the relation defined. There is good agreement between calculated and measured values of ξ′.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00613274
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Low-temperature oxidation of Fe-24 wt.%Cr (1979)
    Springer
    Oxidation of metals 13 (1979), S. 437-456 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00605109
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Thickness determination of oxide films on iron by electron back-scattering Mössbauer spectroscopy (1978)
    Springer
    Oxidation of metals 12 (1978), S. 247-256 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00616099
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    The oxidation of Ni-70 wt.%Cr in oxygen between 1073 and 1473°K (1980)
    Springer
    Oxidation of metals 14 (1980), S. 263-277 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; Ni-Cr alloys ; two-phase alloys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Oxidation of the relatively simple, two-phase alloy Ni-70 wt.%Cr in oxygen between 1073 and 1473°K results in the formation of a Cr2O3 scale containing less than O.5 wt.% Ni in solid solution. The oxidation kinetics are irreproducible for an initial period, which is brief at 1073 and 1273°K but much more pronounced at 1473°K, both in duration and degree. This behavior is associated with the failure of the protective Cr2O3 scale. However, after longer periods a compact layer of Cr2O3 becomes established under isothermal conditions and results in a change to more reproducible kinetics, especially at 1073 and 1273°K. Oxidation causes chromium depletion and the formation of a single-phase zone which separates the scale and the two-phase bulk alloy. The depth of Cr2O3 internal oxide coincides with this zone. The oxidation behavior is compared with that of more Ni-rich, single-phase Ni-Cr alloys, with particular reference to the effects of the constitution of the underlying alloy and the integrity of the protective oxide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00604568
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Oxidation of nickel-manganese alloys in the temperature range 873–1273 K (1982)
    Springer
    Oxidation of metals 18 (1982), S. 295-314 
    Details
    ISSN: 1573-4889
    Keywords: Nickel-manganese alloys ; oxidation ; solid solution scales ; internal oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Ni-Mn alloys containing up to 38% Mn have been oxidized in pure oxygen between 873 and 1273 K and the parabolic rate constants measured. The scale morphologies and oxide compositions are interpreted in terms of modifications to the scale on pure Mn caused by the presence of Ni. The scales are composed predominantly of two layers at all temperatures, giving the sequences of phases alloy/cubic monoxide (Ni, Mn)O/ternary spinel, with the cubic (Ni, Mn)O layer always having the greater thickness. There is limited evidence for a third, very thin, outer layer in the scales on all alloys at 873 K and for Ni-38%Mn at 1073 K, which is tentatively considered to be Mn2O3, giving layers in the order alloy/cubic monoxide/ternary spinel/Mn2O3, by analogy with the scale formed on pure Mn. The distribution of the alloy components in the scale is discussed in relation to the Ni-Mn-O phase diagram and in terms of recent theoretical treatments of solid solution scale formation on binary alloys, as far as the available diffusion data allow. The occurrence of internal and intergranular oxidation and the formation of a Mn-depleted zone coincident with the band of uniform internal oxide are considered briefly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00656573
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Tentacle contraction inDiscophrya collini: The effects of ionophore A23187 and ruthenium red on Ca2+-induced contraction and uptake of extracellular calcium (1984)
    Springer
    Protoplasma 122 (1984), S. 125-131 
    Details
    ISSN: 1615-6102
    Keywords: Calcium ; Contraction ; Discophrya ; Ionophore A23187 ; Ruthenium red ; Tentacles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The tentacles of the suctorian protozoonDiscophrya collini are stimulated to contract by externally applied Ca2+. The role of extracellular Ca2+ in tentacle contraction was studied by monitoring45Ca2+ uptake, using ionophore A23187 to facilitate membrane transport of calcium and ruthenium red (RR) as an inhibitor of transport. The degree of tentacle retraction was dependent upon external Ca2+ concentration and studies with45Ca2+ using scintillation counting indicated a linear relationship between external Ca2+ concentration and Ca2+ uptake. Uptake of Ca2+ was enhanced in the presence of the ionophore while RR caused little inhibition.45Ca2+ uptake was only partially inhibited by RR when cells were subjected to a Ca2+, ionophore and RR mixture. Grain counts from light microscope autoradiographs after treatment of cells with45Ca2+/ionophore,45Ca2+/RR or45Ca2+ alone showed heavy, light and intermediate labelling respectively. In all instances the grains were evenly distributed within the cell. These observations are interpreted as supporting the suggestion that the ionophore enhances both the uptake of extracellular Ca2+ and release of Ca2+from an internal source, while the RR could only partially prevent movement of Ca2+ through the plasma mebrane. A model is presented suggesting that tentacle retraction is mediated by cytosolic Ca2+ levels which are determined by the fluxing of Ca2+ across the plasma membrane and the membrane of elongate dense bodies which act as internal Ca2+ reservoirs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279445
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    The intestinal handling of calcium by the rat in vivo, as affected by cortisol. Effect of dietary calcium supplements (1978)
    Springer
    Calcified tissue international 25 (1978), S. 1-6 
    Details
    ISSN: 1432-0827
    Keywords: Calcium ; Intestine ; Growth ; Cortisol ; Hydroxyproline ; Parathyroid hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary This paper reports the effects of cortisol on intestinal management of calcium and on related changes on bone metabolism. Five groups of 12 rats each fed a standard diet (0.8% Ca) received 2, 6, 16, 32, and 128 mg/kg/day of cortisol hemisuccinate, subcutaneously. After 16 days, intestinal absorption and excretion of Ca were measured with the aid of45Ca. True Ca absorption increased as a function of dose up to 16 mg/kg/day and remained high with the larger doses. Endogenous fecal Ca excretion increased exponentially as a function of the dose from 16 mg/kg/day onwards. Therefore, a dual effect was observed: (a) an increase in true Ca absorption at low cortisol doses (which increased net Ca absorption); and (b) an increase in endogenous fecal Ca excretion at high doses (which reduced net Ca absorption). In no case was a depression of true Ca absorption observed. Growth rate and food conversion efficiency were depressed only with a cortisol dose of 128 mg/kg/day. The urinary excretion of hydroxyproline, pyrophosphate, and aminopolysaccharides decreased with low doses and increased above normal levels with the highest dose. When animals treated with 128 mg/kg/day of cortisol were fed Ca-enriched diets, net Ca absorption improved. Simultaneously, growth rate and food conversion efficiency approached normal values. In these experiments, net absorption of Ca was found to be inversely related to urinary excretion of hydroxyproline. The urinary rate of excretion of hydroxyproline is suggested as an indicator of the effect of a Ca supplement on cortisol affected connective tissue turnover.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02010743
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Effects of 1α-hydroxy vitamin D3 on the rachitic chick intestine: A comparison to the effects of 1,25-dihydroxyvitamin D3 (1980)
    Springer
    Calcified tissue international 32 (1980), S. 9-17 
    Details
    ISSN: 1432-0827
    Keywords: 1α-Hydroxy vitamin D3 ; 1,25-Dihydroxyvitamin D3 ; Calcium ; Transport ; Intestine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The timed sequence of events following the oral administration of 1α-hydroxy vitamin D3 (1αOHD3) to rachitic chicks was compared to that following a comparable dose of 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3). RNA polymerase activity was maximally increased 20% by 1αOHD3 within 1 to 2 h and returned to control values after 8 h. Alkaline phosphatase activity was stimulated by 4 h and was maximal (3- to 5-fold increase) at 24 h. Calcium binding protein (CaBP) was detected initially within epithelial cells at the proximal end of the villus (just above the crypt) 6 to 8 h after 1αOHD3 administration, in epithelial cells lining the proximal half of the villus by 24 h, and in epithelial cells along nearly the entire villus by 48 h. At no time did goblet cells contain CaBP. Serum calcium concentrations were significantly elevated in 2 h and maximal by 12 h (an increase of 3.6 mg/dl). Calcium accumulation by the intestinal mucosa in vitro was increased by 6 to 8 h and maximal (60% increase over controls) at 24 h. Phosphate accumulation by the intestinal mucosa in vitro was increased by 6 h and maximal (105% increase over controls) between 8 and 24 h. 1,25(OH)2D3 increased CaBP and calcium accumulation by 4 h, 2 h sooner than did 1αOHD3. 1,25(OH)2D3 decreased serum calcium levels and increased serum phosphate levels at 2 h unlike 1αOHD3. No difference in the effects of these compounds on alkaline phosphatase activity, RNA polymerase activity, and phosphate accumulation could be demonstrated. These results are consistent with the possibility that 1αOHD3 may not require conversion to 1,25(OH)2D3 for all of its biological effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02408517
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...