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  • 1
    Electronic Resource
    Electronic Resource
    Interpretation of transmission electron microscope images of amorphous silicon/germanium and silicon/iron multilayers (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 1371-1376 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We show that the observed contrast in transmission electron microscope images of multilayer specimens composed of amorphous materials can be understood in terms of the scattering of electrons passing through the material. This leads us to develop a simple method of analyzing the image contrast to give quantitative information about the thicknesses of individual layers, which cannot be obtained by any other technique. The results of this analysis for images of silicon/germanium and silicon/iron multilayers are in good agreement with the results of small-angle x-ray scattering and the readings of quartz thickness monitors during the deposition of the layers. The accuracy of the thickness measurements we obtain from transmission electron microscope images is 7% for the average layer thickness of a single component and 10% for the thickness of individual layers when the layer thickness is about 4 nm, which is comparable to the accuracy which can be attained for crystalline layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347275
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  • 2
    Electronic Resource
    Electronic Resource
    Some Organic Tetrafluoroborates. (1966)
    s.l. : American Chemical Society
    Journal of chemical & engineering data 11 (1966), S. 614-615 
    Details
    ISSN: 1520-5134
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/je60031a053
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  • 3
    Electronic Resource
    Electronic Resource
    Semiconductor Particle Detectors (1962)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Nuclear and Particle Science 12 (1962), S. 189-220 
    Details
    ISSN: 0066-4243
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.ns.12.120162.001201
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  • 4
    Electronic Resource
    Electronic Resource
    Cell-substrate interactions during amoeboid locomotion of neutrophil leukocytes
    Amsterdam : Elsevier
    Experimental Cell Research 126 (1980), S. 453-458 
    Details
    ISSN: 0014-4827
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0014-4827(80)90286-4
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  • 5
    Electronic Resource
    Electronic Resource
    A challenge for 21st century molecular biology and biochemistry: what are the causes of obligate autotrophy and methanotrophy? (2004)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology reviews 28 (2004), S. 0 
    Details
    ISSN: 1574-6976
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We assess the use to which bioinformatics in the form of bacterial genome sequences, functional gene probes and the protein sequence databases can be applied to hypotheses about obligate autotrophy in eubacteria. Obligate methanotrophy and obligate autotrophy among the chemo- and photo-lithotrophic bacteria lack satisfactory explanation a century or more after their discovery. Various causes of these phenomena have been suggested, which we review in the light of the information currently available. Among these suggestions is the absence in vivo of a functional α-ketoglutarate dehydrogenase. The advent of complete and partial genome sequences of diverse autotrophs, methylotrophs and methanotrophs makes it possible to probe the reasons for the absence of activity of this enzyme. We review the role and evolutionary origins of the Krebs cycle in relation to autotrophic metabolism and describe the use of in silico methods to probe the partial and complete genome sequences of a variety of obligate genera for genes encoding the subunits of the α-ketoglutarate dehydrogenase complex. Nitrosomonas europaea and Methylococcus capsulatus, which lack the functional enzyme, were found to contain the coding sequences for the E1 and E2 subunits of α-ketoglutarate dehydrogenase. Comparing the predicted physicochemical properties of the polypeptides coded by the genes confirmed the putative gene products were similar to the active α-ketoglutarate dehydrogenase subunits of heterotrophs. These obligate species are thus genomically competent with respect to this enzyme but are apparently incapable of producing a functional enzyme. Probing of the full and incomplete genomes of some cyanobacterial and methanogenic genera and Aquifex confirms or suggests the absence of the genes for at least one of the three components of the α-ketoglutarate dehydrogenase complex in these obligate organisms. It is recognized that absence of a single functional enzyme may not explain obligate autotrophy in all cases and may indeed be only be one of a number of controls that impose obligate metabolism. Availability of more genome sequences from obligate genera will enable assessment of whether obligate autotrophy is due to the absence of genes for a few or many steps in organic compound metabolism. This problem needs the technologies and mindsets of the present generation of molecular microbiologists to resolve it.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/j.femsre.2003.12.001
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  • 6
    Electronic Resource
    Electronic Resource
    Sulphur bacteria first again (1987)
    [s.l.] : Nature Publishing Group
    Nature 326 (1987), S. 830-830 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] ON PAGE 891 of this issue1 Friedhelm Bak and Heribert Cypionka describe how some anaerobic sulphur bacteria can obtain energy for growth by the fermentation of inorganic sulphur compounds in a manner that has never been described before. Their observations open up a new field of study in microbial ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/326830a0
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  • 7
    Electronic Resource
    Electronic Resource
    Studies on the growth ofThiobacillus ferrooxidans (1974)
    Springer
    Archives of microbiology 95 (1974), S. 165-180 
    Details
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Suspensions ofThiobacillus ferrooxidans in Warburg flasks oxidized ferrous iron and coupled14CO2 fixation to the oxidation. The sulphates of zinc, cobalt, copper, nickel or uranium (0.1–1.0 M) depressed the rate of Fe2+ oxidation: nickel and uranyl ions were the most inhibitory. Uranyl, copper and nickel ions inhibited iron-dependent CO2-fixation, the two former producing a marked uncoupling effect on CO2-fixation, similar to that produced by 2:4-dinitrophenol. Molybdate also inhibited iron oxidation. Incorporation of14C-labelled amino acids and glucose was largely dependent on energy from ferrous-iron oxidation and was also strongly inhibited by uranyl sulphate. Kinetic analysis of the inhibition of iron-oxidation by uranium indicated mixed competitive and non-competitive inhibition. Little binding of238U,63Ni or59Fe toT. ferrooxidans was observed and the effects of uranium were concluded to result mainly from loose binding at sites on the cell membrane concerned with iron-oxidation and possibly the transport of other metals. Molybdate probably interfered with sulphate-dependent steps of iron oxidation. Uncoupling of CO2-fixation probably resulted in part from interference with energy metabolism and could depend on transport of uranyl ions through the cell membrane. CO2-fixation by an uraniumtolerant culture (U+) was less sensitive to uranyl-inhibition than that by the wild-type strain (U−), but iron oxidation and CO2-fixation were much more sensitive to uranium when the U− organisms were previously cultured on thiosulphate rather than ferrous iron.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02451758
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  • 8
    Electronic Resource
    Electronic Resource
    Studies on the growth of Thiobacillus ferrooxidans (1974)
    Springer
    Archives of microbiology 98 (1974), S. 167-174 
    Details
    ISSN: 1432-072X
    Keywords: Thiobacillus ferrooxidans ; Iron Oxidation ; Potassium ; Monovalent Cations ; Uranium Toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. Oxidation of ferrous iron by Thiobacillus ferrooxidans proceeded at the same rates in media grossly deficient in potassium as in media with 4.56 mM K+ added. 2. Iron oxidation in “potassium-free” medium was markedly inhibited by the addition of 10-5 M K+ or Na+ (as sulphates), compared with normal or accelerated oxidation at lower or higher concentrations. 3. Chlorides of sodium or potassium were inhibitory under conditions where the sulphates were not; the concentrations of chlorides required to inhibit development depended on the total potassium content of the medium. 4. Thallium and rubidium were growth inhibitory at 10-4 M in the “potassium-free” medium, but were not toxic at 10-3 M in the normal medium. 5. Inhibition of growth by 2 mM uranyl sulphate was partially relieved by 200 mM K+, Na+, Li+ or NH4 + added to the normal medium as sulphates. 6. Increased H2SO4 concentration increased uranium toxicity without affecting the normal growth rates. 7. The results are discussed in relation to the possible presence in T. ferrooxidans of two K+-transport systems of different reaction to external K+-concentration, and the possible effects of uranium on membrane-dependent processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425279
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  • 9
    Electronic Resource
    Electronic Resource
    In vitro Transformation of Syrian Hamster Embryo Cells by Diverse Chemical Carcinogens (1972)
    [s.l.] : Nature Publishing Group
    Nature 235 (1972), S. 278-280 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] More recently, normal Syrian hamster embryo cells have been used to determine directly the frequency of transformation by chemical carcinogens5,6. This phenomenon is inductive rather than selective, as the increase in frequency of transformation on a per cell basis is proportional to concentration ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/235278a0
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  • 10
    Electronic Resource
    Electronic Resource
    Characteristics of a moderately thermophilic and acidophilic iron-oxidizing Thiobacillus (1978)
    Springer
    Applied microbiology and biotechnology 5 (1978), S. 291-299 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Thiobacillus TH1 is an acidophilic chemolithotrophic heterotroph growing at temperatures up to about 50°C on media containing ferrous iron or pyrite when supplemented with yeast extract or glutathione. Virtually no carbon dioxide fixation occurred during growth on iron with yeast extract. Its DNA contains 48 mol % guanine + cytosine. The organism effects the thermophilic leaching of metals from pyrite, chalcopyrite, CuS, and copper concentrates. Oxidation of soluble ferrous iron at pH 1.6 was competitively inhibited by ferric iron and had a Km of 7.3 mM FeSO4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00504717
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