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  • 1970-1974  (7)
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Material
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Survival of frozen-thawed bovine red cells as a function of the permeation of glycerol and sucrose (1974)
    Springer
    The journal of membrane biology 15 (1974), S. 137-158 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Bovine red cells, like other cells, exhibit maximum survival when frozen at certain optimum rates. Cells cooled more slowly are apparently injured by alterations in the cytoplasm or surrounding medium such as the increased concentration of solutes induced by extracellular ice formation. Additives like glycerol protect against this “slow” freezing injury. It has been generally believed that such protection requires permeation by the additive, but we have found that this supposition is not valid for the bovine red cell. Cells were suspended in 1, 2 or 3m glycerol at 20, 15 or 0°C for 0.7 to 30 min or more and then frozen to −196°C at 43 or 1.7°C/min. In nearly all cases, the percentage survival after thawing was as high for cells held in glycerol for 1 min or less prior to freezing as for cells held in glycerol for 30 min, and it was as high for cells held at 0°C as for cells held at 20°C. Survivals were the same for these times and temperatures of exposure in spite of the fact that the osmolal ratio of glycerol to salts in the cell after 30 min at 20°C, for example, was as much as 800 times greater than that in cells held at 0°C for 0.7 min. In addition, the survival after a contact of 1 or 30 min with 2.3 osmolal sucrose was the same as that after exposure to 2.3 osmolal glycerol even though the bovine red cell is impermeable to sucrose. Although exposures of 1 and 30 min to glycerol yielded similar survivals, exposures for intermediate times produced a transitory but dramatic decrease in survival. The dip occurred after longer periods of incubation when the concentration of glycerol was increased and when the incubation temperature was decreased. No dip was evident in cells chilled to 0°C or in cells frozen in sucrose. Thus, the dip seems to be associated in some way with partial permeation of glycerol prior to freezing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870085
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Permeability of the bovine red cell to glycerol in hyperosmotic solutions at various temperatures (1974)
    Springer
    The journal of membrane biology 15 (1974), S. 107-136 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary A central tenet in cryobiology is that low-molecular-weight protective solutes such as glycerol must permeate cells in high concentration in order to protect them from freezing injury. To test this supposition, it is necessary to estimate the amount of solute that has permeated a cell prior to freezing. The amount in bovine red cells was estimated from the flux equation $${{ds} \mathord{\left/ {\vphantom {{ds} {dt}}} \right. \kern-\nulldelimiterspace} {dt}} = P_\gamma A[(activity external solute) - (activity internal solute)].$$ Solving the equation required estimates ofP γ, the permeability constant for the solute. Estimates for glycerol in bovine red cells were made in two ways: (1) by measuring the time to 50% hemolysis of red cells suspended in isosmotic or hyperosmotic (1 to 3m) solutions of glycerol that were hypotonic with respect to NaCl, and (2) by measuring the time required for red cells in hyperosmotic solutions of glycerol in isotonic salinebuffer to become susceptible to osmotic shock upon 10-fold dilution with isotonic saline-buffer. The measurements were made at 0, 10, 15 and 20°C. The values by the second technique ranged from 2.3×10−6 cm/min to 2.7×10−6 cm/min at 20°C, depending on the concentration of glycerol. The values by the first technique were 0 to 30% lower. Both techniques yielded about the same activation energy for permeation between 0 and 20°C, 21 kcal/mole. This is equivalent to a halving of the permeation rate for every 5° drop in temperature. Expressing the flux equation in the formulation of irreversible thermodynamics changed the value ofP by less than 10%, probably because σ, the reflection coefficient, is 0.95 at 25°C. Expressing the driving force as the difference in molality or osmolality of glycerol, rather than as the difference in activity, however, had somewhat greater effects on the numerical values ofP, but had no effect on the activation energy. It is concluded that estimates ofP based on differences in activities and on the osmotic shock technique are the least subject to error. The use of the usual irreversible thermodynamic equations to express the flux may be a misleading refinement, in that the assumptions underlying them become questionable for concentrations of glycerol as high as 1, 2, or 3m.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870084
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  • 3
    Electronic Resource
    Electronic Resource
    Search for high frequency optical variations in Vela XR-1 (1974)
    [s.l.] : Nature Publishing Group
    Nature 248 (1974), S. 492-492 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/248492a0
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Numerical experiments in collisionless systems (1971)
    Springer
    Astrophysics and space science 14 (1971), S. 73-90 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00649196
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    The influence of soil micro-organisms on the growth and chemical composition of soybean (1970)
    Springer
    Plant and soil 32 (1970), S. 146-160 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A plastic film isolator was adapted for the growth of soybeans in sterile soil, sterile reinoculated soil, and unsterilized soil. The presence of micro-organisms significantly increased the mass of tops and roots as well as the plant content of Ca, Mg, Fe, Al, Cu, Zn, and Mo. Plant content of N, P, and K was not affected by microbial activity, while manganese, made available by steam-sterilization, was oxidized to unavailable forms by the soil microflora. The mixed microflora influenced the quantity and distribution of free amino acids within the plant but did not affect the distribution of amino acids within the crude protein fraction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01372853
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    The influence of soil micro-organisms on the growth and chemical composition of soybean (1970)
    Springer
    Plant and soil 32 (1970), S. 146-160 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A plastic film isolator was adapted for the growth of soybeans in sterile soil, sterile reinoculated soil, and unsterilized soil. The presence of micro-organisms significantly increased the mass of tops and roots as well as the plant content of Ca, Mg, Fe, Al, Cu, Zn, and Mo. Plant content of N, P, and K was not affected by microbial activity, while manganese, made available by steam-sterilization, was oxidized to unavailable forms by the soil microflora. The mixed microflora influenced the quantity and distribution of free amino acids within the plant but did not affect the distribution of amino acids within the crude protein fraction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01372853
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Soil inorganic polyphosphates of microbial origin (1973)
    Springer
    Plant and soil 38 (1973), S. 651-655 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Extraction of eight soils with cold 0.5 M perchloric acid yielded acid-labile phosphates in four of them which were shown to be naturally occurring inorganic polyphosphates of microbial origin. The amounts estimated were in the range of 5.0 to 11.1 µg P/g soil. Gel filtration through Sephadex G-25 indicated variation with respect to chain lengths and molecular weights of these polyphosphates. Addition of excess amounts of orthophosphate to 14-day incubated glucose-amended soils resulted in accumulation of larger quantities (up to 22.0 µg P/g soil) of acid-labile polyphosphates in some soils. re]19720407
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010703
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    Paper (German National Licenses)
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