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Träfflista för sökning "WFRF:(Paul J) srt2:(1985-1989)"

Sökning: WFRF:(Paul J) > (1985-1989)

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1.
  • Christakopoulos, Paul, et al. (författare)
  • Direct fermentation of cellulose to ethanol by Fusarium oxysporum
  • 1989
  • Ingår i: Enzyme and microbial technology. - : Elsevier BV. - 0141-0229 .- 1879-0909. ; 11:4, s. 236-239
  • Tidskriftsartikel (refereegranskat)abstract
    • The cellulase hyperproducing strain F3 of Fusarium oxysporum fermented glucose, xylose, cellobiose, and cellulose directly to ethanol. Conversion of cellulose to ethanol was markedly affected by the pH of both aerated preculture and nonaerated fermentation. Optimum values of cellulose conversion to ethanol were obtained when aerated and nonaerated processes were carried out at pH 5.5 and 6, respectively. Maximum ethanol concentrations of 9.6 and 14.5 g l−1, corresponding to 89.2 and 53.2% of the theoretical yield, were obtained when the fungus was grown under nonaerated conditions at 34°C for 6 days in a medium containing 20 and 50 g l−1cellulose, respectively.
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2.
  • Lundberg, Peter, et al. (författare)
  • Phosphorus-31 and Nitrogen- 14 NMR Studies of the Uptake of Phosphorus and Nitrogen Compounds in the Marine Macroalgae Ulva lactuca
  • 1989
  • Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 89:4, s. 1380-1387
  • Tidskriftsartikel (refereegranskat)abstract
    • Cytoplasmic phosphomonoesters and inorganic phosphate, as well as vacuolar inorganic phosphate and polyphosphates, gave rise to the major peaks in (31)P nuclear magnetic resonance (NMR) spectra of the marine macroalgae Enteromorpha sp., Ceramium sp., and Ulva lactuca which were collected from the sea. In contrast, NMR-visible polyphosphates were lacking in Pylaiella sp. and intracellular vacuolar phosphate seemed to act as the main phosphorus store in this organism. In laboratory experiments, polyphosphates decreased in growing U. lactuca which was cultivated in continuous light under phosphate-deficient conditions. In contrast, the same organism cultivated in seawater with added phosphate and ammonium, accumulated phosphate mainly in the form of polyphosphates. When nitrate was provided as the only nitrogen source, accumulation of polyphosphates in the algae decreased with increasing external nitrate concentration. From the chemical shift of the cytoplasmic Pi peak, the cytoplasmic pH of superfused preparations of Ulva was estimated at 7.2. The vacuolar pH, determined from the chemical shifts of the vacuolar Pi and the terminal polyphosphate peaks, was between 5.5 and 6.0. The intracellular nitrate and ammonium levels in U. lactuca were determined by (14)N NMR. Both nitrogen sources were taken up and stored intracellularly; however, the uptake of ammonium was much faster than that of nitrate.
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4.
  • Paul, Jan, et al. (författare)
  • The interaction of CO and O2 with the (111) surface of Pt3Ti
  • 1986
  • Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 177:1, s. 121-138
  • Tidskriftsartikel (refereegranskat)abstract
    • The electronic properties of clean and partly oxidized Pt3Ti(111) surfaces have been studied utilizing carbon monoxide both as a probe and as a reducing agent. Vibrational frequencies and desorption profiles of chemisorbed CO as well as ion scattering and angular resolved X-ray photoelectron spectroscopy (XPS) suggest that the first atomic layer of annealed Pt3Ti(111) is quasi-pure platinum. Scarcely any (θ ≈ 0.01) dissociation of CO was observed. Minor shifts of vibrational frequencies and desorption temperatures compared to Pt(111) and a p(2 × 2) "reconstruction" of the clean surface reveal some influence of the bulk. Auger spectroscopy, XPS, and ion scattering all show an increased titanium signal as a result of oxidation. Surface bound atomic oxygen gives a vibrational band around 650 cm-1 which coincides with infrared absorption spectra of TiO2. Flashing with CO shifts the band to 500 cm-1. Correlated with this shift we observe (i) CO2 desorption at a temperature well above that observed for Pt(111)/O, (ii) an altered Ti XPS signal, and (iii) a reduced oxygen concentration. Subsequently adsorbed CO molecules vibrate at the same frequencies as on the bare surface, give the same c(4 × 2) LEED pattern, and desorb at the same temperatures but with reduced intensity, in all proving that the surface oxide only acts as a site-blocker with respect to the metal surface. Our current understanding of these observations is that oxygen creates "islands of TiO2", segregated to the surface but with no electronic influence on remaining areas of the platinum enriched metal surface. The hexacoordinated Ti4+ ions on the surface of these islands are reduced by CO to pentacoordinated Ti3+ species. The vibrational shift, 650 to 500 cm-1, can be understood by the dipole active bands of a triatomic O-Ti4+ -O vibrator compared to a diatomic Ti3+-O vibrator.
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5.
  • Weich, Rainer G., et al. (författare)
  • Phosphorus-31 NMR studies of cell wall-associated calcium-phosphates in Ulva lactuca
  • 1989
  • Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 90:1, s. 230-236
  • Tidskriftsartikel (refereegranskat)abstract
    • Phosphate concentrations in the range 0.1 to 2.0 millimolar induced the formation of extracellular amorphous calcium-phosphates in the cell wall of the marine macro algae Ulva lactuca when they were cultivated in light in seawater at 20°C. A broad resonance representing these compounds as well as resonances for extracellular orthophosphate and polyphosphates could be followed by 31P-nuclear magnetic resonance spectroscopy. The presence of the calcium-phosphate made the cells brittle and it inhibited the growth of the macro algae and caused mortality within 1 week. The formation of the calcium-phosphates was influenced by the external phosphate concentration, the extracellular pH and the nature and concentration of the external nitrogen source. Furthermore, no formation of these compounds was observed when Ulva lactuca was cultivated in the dark, at low temperatures (5°C) or in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea. The complex could be removed through washes with ethylenediaminetetraacetate; this treatment did not alter the intracellular pH or the orthophosphate and polyphosphate pools and it restored growth.
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