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  • 1
    Electronic Resource
    Electronic Resource
    Effects of calcium, strontium, and magnesium on the coccolithophorid Cricosphaera (Hymenomonas) carterae. II. Cell division (1976)
    Springer
    Marine biology 34 (1976), S. 17-22 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of calcium-deficiency, magnesium-deficiency and strontium enrichment on cell division in the alga Cricosphaera (Hymenomonas) carterae have been studied. Cell growth was reduced at 10-3 M Ca and was absent at 5x10-4 M Ca and lower concentrations. The addition of Sr to Ca-deficient media enabled cells to divide, the effect increasing with Sr concentration. When 4.6x10-4 M Sr was added to media containing 10-4 M Ca, the rate of division and the final cell concentration were comparable to the control (10-2 M Ca). Strontium was 20 times more effective than Ca. The rate of growth was also examined at various Mg concentrations. Cell division was absent, or nearly so, in Mg concentrations below 4.2x10-5 M. Cell size increased progressively as the Mg concentration decreased; however, the lowest protein concentration was found in the absence of Mg. In media lacking Mg, cells exhibited changes in ultrastructure including rounding-up and apparent fragmentation of chloroplasts and an increase in vacuole size. Also, the number of mitochondria per cell section increased 2.9 times in the absence of Mg while the total cross-sectional area remained the same, indicating fragmentation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00390782
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of calcium, strontium, and magnesium on the coccolithophorid Cricosphaera (Hymenomonas) carterae. I. Calcification (1976)
    Springer
    Marine biology 34 (1976), S. 11-16 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The present investigation concerns the effects of calcium, strontium, and magnesium on calcification and mineralogy of the calcified bodies (coccoliths) of the coccolithophorid Cricosphaera (Hymenomonas) carterae. The capacity of cells to calcify in various concentrations of these ions was examined following preliminary decalcification in CO2. At a concentration of 10-2 M Ca, 75% of the cells formed coccoliths within 24 h and almost all cells were recalcified after 2 days. At 10-3 or 10-4 M Ca no recalcification occurred. However, with the addition of Sr to the Ca-deficient media, calcification took place as shown by observations of coccoliths and by analysis of Ca. The percentage of calcified cells increased with increasing concentrations of Sr. Strontium added to a Ca-deficient media was much more effective than an equivalent concentration of Ca. No Sr was deposited in the coccoliths. X-ray analysis demonstrated that calcite was deposited by cells in all concentrations of Ca and Sr at which calcification took place. At concentrations of Mg in the media from O. O to 4.2×10-2 M, the cells retained their ability to calcify, although calcification was markedly reduced in the absence of Mg. In low Mg concentrations (1.3×10-4 and 4.2×10-6 M), the coccoliths were 60% calcite and 40% aragonite, and in teh absence of Mg, only calcite was formed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00390781
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  • 3
    Electronic Resource
    Electronic Resource
    Thyroid Hormone Resistance (1992)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Medicine 43 (1992), S. 363-375 
    Details
    ISSN: 0066-4219
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.me.43.020192.002051
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  • 4
    Electronic Resource
    Electronic Resource
    26.1% solar cell efficiency for Ge mechanically stacked under GaAs (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 3010-3015 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have processed a diffused Ge wafer into a Ge concentrator solar cell and mechanically stacked it under a GaAs cell fabricated by Varian. We measured this stack's efficiency to be 26.1% for terrestrial air mass 1.5 direct (AM1.5D) conditions at a 285× concentration ratio. We showed that this efficiency is limited by optical absorption in the Varian GaAs cell caused by high 2–4 (1018) cm−3 substrate doping. We used a 2×1017 cm−3 doped GaAs filter to estimate the stack efficiency as 27.4%, which would be achieved with the same Varian GaAs cell formed on a lower doped substrate. We project efficiencies assuming the best properties reported for a GaAs device. This gives a 29.6% efficiency for an improved, planar Ge cell and 31.6% efficiency for a proposed point contact geometry for the Ge cell. The corresponding space (AM0) efficiencies at a 159× concentration ratio range from the 23.4% value we measured on the stack up to 28.4% projected for the point contact Ge place under the best GaAs cell. We showed that Ge cells give higher efficiencies than Si when stacked under GaAs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339389
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  • 5
    Electronic Resource
    Electronic Resource
    GaAs films grown by vacuum chemical epitaxy using thermally precracked trimethyl-arsenic (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 299-301 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Trimethyl-arsenic (TMAs) is used as a source of arsenic for GaAs film growth. In the process used, vacuum chemical epitaxy, TMAs is thermally decomposed into arsenic upstream in a hot cracker furnace. The arsenic and stable hydrocarbons are then transported in vacuum without condensation to the epitaxial growth zone. The hole carrier concentration and carbon content in grown films are studied via Hall, electrochemical profile, and secondary ion mass spectroscopy as a function of cracker furnace design. It is shown that when the TMAs decomposition efficiency is poor, the carbon content can be as high as 1019/cm3 but for a more efficient cracker, the carbon content can be reduced into the 1016/cm3 range. Toxic injury hazards can be reduced substantially by substituting TMAs for the more widely used arsine in GaAs growth systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339145
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  • 6
    Electronic Resource
    Electronic Resource
    Distribution and Mobility of Voltage-gated Ion Channels in Skeletal Muscle (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 479 (1986), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1986.tb15583.x
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  • 7
    Electronic Resource
    Electronic Resource
    Studies on the biology of fish bone. III. Ultrastructure of osteogenesis and resorption in osteocytic (cellular) and anosteocytic (acellular) bones (1979)
    Springer
    Calcified tissue international 28 (1979), S. 43-56 
    Details
    ISSN: 1432-0827
    Keywords: Bone resorption ; Osteogenesis ; Fish bone ; Osteocytes ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The comparative ultrastructure of fish bone osteogenesis and resorption induced by scale removal was described in the osteocytic (cellular-boned)Carassius auratus and the anosteocytic (acellular-boned)Tilapia macrocephala. Osteocytes, present in osteocytic bone, were lacking in anosteocytic bone. In osteocytic bone the osteoblast secreted a collagenous preosseous matrix in which it became enmeshed and then was termed a preosteocyte. When the preosseous matrix mineralized, the preosteocyte was termed an osteocyte and was completely surrounded by bone. In anosteocytic bone the osteoblasts receded from the mineralizing front and never became trapped as osteocytes. During resorption, types A and B resorptive cells, present in both bone types, invaded the matrix and demineralized the osseous zone. These cells were characterized by large amounts of granular endoplasmic reticulum and intracellular inclusions containing crystal-like material. Although functionally similar to mammalian osteoclasts, these cells lacked a characteristic ruffled border and were not multinucleated. The osteocytes of cellular bone did not appear to be involved during demineralization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441217
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  • 8
    Electronic Resource
    Electronic Resource
    A multisurface tissue propagator for the mass-scale growth of cell monolayers (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 10 (1968), S. 601-615 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Various multisurface mass-scale tissue culture propagators ranging in capacity up to 200 liters have been developed at Abbott Laboratories. These patented units consist, of an enclosed vessel containing a multiplicity of separated glass plates or disks on which cells may attach and proliferate. Means for mixing and aeration of the medium are provided. Sample ports facilitate the addition of cultures and media, the withdrawal of samples, the washing of cell monolayers, and the harvesting of cells and cell products. The large cell growth surface per occupied volume, the provision for separating tissue cells from media simply and easily, and the minimization of the amount of labor required per cell growth area are some of the many advantages of the multisurface tissue propagator that are described.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260100506
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