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  • 1
    Electronic Resource
    Electronic Resource
    Hydrogen Production by Rumen Holotrich Protozoa: Effects of Oxygen and Implications for Metabolic Control by In Situ Conditions (1989)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 36 (1989), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Experiments with washed suspensions of holotrich protozoa (Isotricha spp. and Dasytricha ruminantium) showed that both organisms have an efficient 0,-scavenging capability (apparent Km values 2.3 and 0.3 μM, respectively). Reversible inhibition of H2, production increased almost linearly with increasing O2 up to 1.5 μM; higher levels of O2 gave irreversible inhibition. In situ determinations of H, CH4, O2, and CO2, in ovine rumen liquor, using a membrane inlet mass spectrometer probe, indicated that O2, was present before feeding at 1-1.5 μM and decreased to undetectable levels (〈0.25 μM) within 25 min after feeding. A transient increase in O2. concentration after feeding occurred only in defaunated animals and resulted in suppression of CH4 and CO2 production. The presence of washed holotrich protozoa decreases the O2 sensitivity of CH4 production by suspensions of a cultured methanogenic bacterium Methanosarcina barkeri. It is concluded that holotrich protozoa play a role in ruminal O2 utilization as well as in the production of fermentation end products (especially short-chain volatile fatty acids) utilized by the ruminant and H, utilized by methanogenic bacteria. These hydrogenosome-containing protozoa thus both control patterns of fermentation by influencing O2 levels, and are themselves regulated by the low ambient O2 concentrations they experience in the rumen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1989.tb01075.x
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  • 2
    Electronic Resource
    Electronic Resource
    Characterization of γ-Fe2O3 homogeneity in magnetic recording media by photoacoustics (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 2405-2407 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The degree of homogeneity of ferric oxide in magnetic tapes has been characterized using photoacoustic techniques. The method is based on excitation of the sample by a modulated laser beam and subsequent detection of its acoustic response via a condenser microphone. The acoustic response is dependent on the local thermal variations in the sample, and is a direct measurement of the distribution uniformity of the particulate metal oxide in the sample. Results of this study provide a potential means for the rapid evaluation of the quality of magnetic recording media.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101534
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  • 3
    Electronic Resource
    Electronic Resource
    Notes on Some Passages in Seneca's Tragedies and the Octavia (1989)
    Cambridge : Cambridge University Press
    The @classical quarterly 39 (1989), S. 186-196 
    Details
    ISSN: 0009-8388
    Source: Cambridge Journals Digital Archives
    Topics: Classical Studies
    Notes: The text quoted above each note is that of the edition of Seneca's tragedies by Otto Zwierlein (Zw.), OCT 1986; numerous passages are discussed in his Kritischer Kommentar zu den Tragüdien Senecas (K.K.), Stuttgart, 1986; various textual suggestions were made in a correspondence with Zw. by B. Axelson (Ax.). Other works on Seneca's tragedies, referred to by the scholar's name only, are: (i)Text and translation: F. J. Miller, Loeb, 1917; L. Herrmann, Budé, 1924–6. (ii)Text with commentary: R. J. Tarrant, Agamemnon (Cambridge, 1976), and Thyestes (Atlanta, 1985); J. G. Fitch, Hercules Furens (Ithaca, 1987). (iii) Text with commentary and translation: Elaine Fantham, Troades (Princeton, 1982); A. J.Boyle, Phaedra (Liverpool, 1987).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1017/S000983880004057X
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  • 4
    Electronic Resource
    Electronic Resource
    Substrate specificity, de novo synthesis and partial purification of polyphenol oxidase derived from the wood-decay fungus,Coriolus versicolor (1989)
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 349-363 
    Details
    ISSN: 1476-5535
    Keywords: Coriolus versicolor ; Wood-decay fungus ; Polyphenol oxidase ; Substrate specificity ; de novo Synthesis ; Partial purification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Coriolus versicolor, a white-rot Basidiomycete, secretes cellulolytic and ligninolytic enzymes as well as polyphenol oxidase (PPO). Whereas the former degrade wood polymers, the latter can convert diphenols to diquinones and oligomerize syringic acid, a lignin derivative. Certain phenolic compounds can serve as disease-resistance factors controlling the proliferation of wood-decay fungi within host tissues. BecauseC. vesicolor can be ‘batch-cultured’, overproduction and enhanced secretion of enzymes of biological and commercial interests are feasible. Reported here are the results of attempts to define the timed appearances of intracellular and extracellular PPO, to assess substrate specificity as well as distinguish synthesis versus activation of intracellular PPO and to partially purify extracellular PPO. These efforts were to provide data enabling cell-free synthesis of PPO, cloning of the gene(s) for the oxidase and the establishment of its subcellular route of secretion. Whereas two protein peaks (6 and 12 days in a 16 day time-course) were observed for dialyzed mycelial homogenates, the homogenates' PPO specific activity rose between 4 and 12 days and then declined. Total extracellular protein content climbed from 6 to 15 days for dialyzed growth medium and the medium's PPO specific activity rose at 4 days post-inoculation and except at 9 days increased linearly to 15 days. When aliquots of dialyzed 12 and 15 day media were added to PPO assay mixtures containing catechol and either syringic or gallic acids, statistically significant differences in PPO specific activity between phenolic substrates were noted. Supplementation of cultures with 1.91 μg cycloheximide ml growth medium−1 (control, growth medium only) together with 0.5 μCi [14C]-leucine revealed that cycloheximide inhibited PPO activity and suppressed [14C]-leucine incorporation into TCA-insoluble cytoplasmic protein. As for PPO partial purification, growth medium dialysis followed by 0–30% (NH4)2SO4 fractionation and subsequent 12 000×g dialyzate centrifugation yielded a 3.27-fold enhancement in PPO specific activity within the 12 000×g supernatant. Chromatography of the latter upon DEAE-Sephadex indicated that PPO exchanged with the DEAE counterion as it could be eluted with high ionic strength salt. These results suggest that: the occurrences of intracellular and extracellular PPO are time-dependent, intracellular PPO is de novo synthesized, the preferred substrate for extracellular PPO appears to be catechol and extracellular PPO can be partially purified by a combination of dialysis and ammonium sulfate fractionation as well as possibly DEAE chromatography and/or Sephadex G-150 gel filtration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569537
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  • 5
    Electronic Resource
    Electronic Resource
    Marginal values in mixed integer linear programming (1989)
    Springer
    Mathematical programming 44 (1989), S. 67-75 
    Details
    ISSN: 1436-4646
    Keywords: Marginal values ; mixed integer programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract For a given optimization problem, P, considered as a function of the data, its marginal values are defined as the directional partial derivatives of the value of P with respect to perturbations in that data. For linear programs, formulas for the marginal values were given by Mills, [10], and further developed by the current author [16]. In this paper, the marginal value formulas are extended to the case of mixed integer linear programming (MIP). As in ordinary linear programming, discontinuities in the value can occur, and the analysis here identifies them. This latter aspect extends previous work on continuity by the current author, [18], Geoffrion and Nauss, [5], Nauss, [11], and Radke, [12], and work on the value function of Blair and Jeroslow, [2]. Application is made to model formulation and to post-optimal analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01587077
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  • 6
    Electronic Resource
    Electronic Resource
    Measurement of anomalously high hydration of (dA) n · (dT) n double helices in dilute solution (1989)
    [s.l.] : Nature Publishing Group
    Nature 340 (1989), S. 321-322 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Ultrasound velocity and density measurements have been used widely to estimate the hydration of ions10, simple molecules, and polymers in dilute solution11. The development of a more sensitive small-scale version of this technique enabled us to investigate the details of the hydration of DNA. This ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/340321a0
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  • 7
    Electronic Resource
    Electronic Resource
    Structures of bis(1,2-diphenylphosphinoethane)nickel(II) dinitrate and bis(cis-1,2-diphenylphosphinoethene)nickel(II) diperchlorate (1989)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 45 (1989), S. 1002-1005 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270189000181
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  • 8
    Electronic Resource
    Electronic Resource
    Gradient recalled echo MR imaging of superior sagittal sinus occlusion (1989)
    Springer
    Neuroradiology 31 (1989), S. 134-136 
    Details
    ISSN: 1432-1920
    Keywords: Gradient recalled echo ; MRI ; Sinus occlusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary With T1-weighted gradient recalled echo (GRE) MR images and flow compensation, we studied the superior sagittal sinus in 3 normal volunteers and 3 patients with sinus occlusion. In these images, sites of patency of the superior sagittal sinus were identified due to the high signal intensity of the normal sinus. Tumor invading the sinus was nearly isointense with cerebral gray matter. T1-weighted GRE imaging proves to be an effective technique to evaluate sinus blood flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00698840
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  • 9
    Electronic Resource
    Electronic Resource
    Kinetics of uranium uptake by the crab Pachygrapsus laevimanus and the zebra winkle Austrocochlea constricta (1989)
    Springer
    Marine biology 101 (1989), S. 323-327 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The crab Pachygrapsus laevimanus and the zebra winkle Austrocochlea constricta were exposed for 40 d to uranium (1.5 to 10 mg l-1) in continuous-flow sea water in separate starved and fed treatments, and the kinetics of uranium bioaccumulation were estimated from an exponential model. Starved and fed crabs took up U at a similar rate, which suggests that sea water was the major source of U to the crab; the fed crabs excreted U more rapidly than the starved crabs and this led to a lower net uptake of U by fed crabs. Fed and starved winkles took up U at similar rates and excreted it at similar rates, so the sea water was also the major source of U to winkles. Crabs took up more U than winkles; the concentration factors were 7 to 18 and 4, respectively. Uranium turnover was quite slow for both species (11 to 36 d) as it was also for winkle shells (6 d); this suggests that the rate-limiting processes which control turnover are biological (e.g. growth or tissue replacement) or physical (e.g. diffusion into the shell) rather than chemical (e.g. precipitation, adsorption or exchange). There was no effect of increasing U concentration in water on the U kinetic parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00428128
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  • 10
    Electronic Resource
    Electronic Resource
    Conduction and blocking properties of a predominantly anion-selective channel from human platelet surface membrane reconstituted into planar phospholipid bilayers (1989)
    Springer
    The journal of membrane biology 109 (1989), S. 113-122 
    Details
    ISSN: 1432-1424
    Keywords: platelet surface membrane ; lipid bilayer ; anion channel ; ion selectivity ; block
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary We have investigated the basic properties of a predominantly anion-selective channel derived from highly purified human platelet surface membrane. Single channels have been reconstituted into planar phospholipid bilayers by fusion of membrane vesicles and recorded under voltage-clamp conditions. The channel is found to have the following properties: (i) Channel activity occurs in bursts of openings separated by long closed periods. (ii) The current-voltage relationship is nonlinear. Channel current is seen to rectify, with less current flowing at positive than at negative voltages. Rectification may be due to asymmetric block by HEPES/Tris buffers. In 450mm KCl, 5mm HEPES/Tris, pH 7.2 the single channel conductance at −40 mV is ∼160 pS and at +40 mV is ∼90 pS. (iii) The conductanceconcentration relationship follows a simple saturation curve. Half maximal conductance is achieved at a concentration of ∼1000mm KCl, and the curve saturates at a conductance of ∼500 pS. (iv) Reversal potentials interpreted in terms of the Goldman-Hodgkin-Katz equation indicate a Cl∶K permeability ratio of 4∶1. (v) The channel accepts all of the halides as well as a number of other anions. The following sequence of relative anion permeabilities (in the presence of K+) is obtained: F−〈acetate−〈gluconate−〈Cl−〈Br−〈I−〈NO 3 − 〈SCN−. (vi) Cations as large as TEA+ are permeant. (vii) Current through the channel is blocked in the presence of DIDS, SITS and ATP, but not by Zn2+.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870850
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