| 1. |
- Carlsson, Andreas, et al.
(författare)
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An electronic tongue as a tool for wet-end monitoring
- 2001
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Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 16:4, s. 319-326
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Tidskriftsartikel (refereegranskat)abstract
- An electronic tongue based on voltammetry and multivariate signal analysis has been evaluated as a tool for characterisation of the chemistry of the wet-end of a paper machine. Measurements were performed on head-box furnish samples from a tissue machine. PLS models, based on electronic tongue data, were made of five reference parameters - pH, conductivity, cationic demand, zeta potential and turbidity. The correlation coefficients for predicted values were for all parameters higher than 0.88. Highly correlated reference parameters might be part of the explanation for the high correlation factors. Still the results, being based on data without e.g. drift compensation, indicate that the electronic tongue has very promising features as a tool for wet-end control. Flexibility, fast response and wide sensitivity spectra make the electronic tongue suitable for a variety of applications.
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| 2. |
- Krantz-Rülcker, C., et al.
(författare)
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Adsorption of IIB-metals by three common soil fungi-comparison and assessment of importance for metal distribution in natural soil systems
- 1996
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Ingår i: Soil Biology and Biochemistry. - : Elsevier. - 0038-0717 .- 1879-3428. ; 28:7, s. 967-975
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Tidskriftsartikel (refereegranskat)abstract
- Interactions of IIb-elements, Zn, Cd and Hg, with three common soil fungi, Trichoderma harzianum, Penicillium spinulosum and Mortierella isabellina, have been studied. The accumulation of the metals by the fungi was studied as a function of pH at constant ionic strength and at concentration levels of the metals representative of natural systems. Two stages of fungal activity were considered in the experiments. The fungi generally exhibited high affinity for metal ions indicated by distribution coefficients (log K-d, in 1 kg(-1)) of about 3.5 +/- 1, 2.5 +/- 1 and 4 +/- 1 for Zn, Cd and Hg, respectively. The pH-dependence of the accumulation as well as the isotherms at constant pH were similar between the fungi, and the maximum capacities were at least 50 mmoles kg(-1) mycelium (dw). Metal accumulation by starved mycelia was almost independent of pH, while non-starved mycelia in two cases accumulated more metals at low pH. Calculations of the distribution of metals in a model soil system of inorganic and organic constituents as well as fungal biomass indicated that the amounts of metal associated to the fungi are negligible at neutral pH. However, due to the ability of these fungi to accumulate metals independently of pH, the fraction of metals associated to fungal biomass at low pH may be significant, and, in some cases, predominant. This illustrates that the effects of fungi on metal distribution in soil should not be neglected, e.g. during a progressing acidification.
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| 3. |
- Krantz-Rülcker, C., et al.
(författare)
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Interactions between a soil fungus, Trichoderma harzianum, and IIb metals—adsorption to mycelium and production of complexing metabolites
- 1993
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Ingår i: Biometals. - : Springer. - 0966-0844 .- 1572-8773. ; 6:4, s. 223-230
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Tidskriftsartikel (refereegranskat)abstract
- Fungi are capable of accumulating metals and, in soil, such accumulation may influence metal speciation and transport. The interactions between a common soil fungus, Trichoderma harzianum, and IIb elements were studied in the present investigation. The accumulation of the metals zinc, cadmium and mercury by starved and non-starved mycelium at different pH was determined by a batch technique using radioactive tracers; uptake of the metals was found to be large, with respective distribution coefficients of about 10(3.5), 10(2.5) and 10(4.0) for zinc, cadmium and mercury, respectively. Metal accumulation by a starved system was largely independent of pH in the range 3-9, where in a non-starved system an increased accumulation of zinc (at 10(-8) m) was observed at low pH (3-5). Potentiometric titrations performed on the two systems revealed significant differences in acid capacities, i.e. values close to zero for the starved system and 500-800 meq kg-1 for the non-starved system. The maximum metal uptake was at least 50 mmol kg-1 at pH 6.5 (calculated from adsorption isotherms). The present findings suggests that in the non-starved system a metabolite is produced and then released when the pH is within a certain range.
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| 4. |
- Krantz-Rülcker, C., et al.
(författare)
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Metal loading and enzymatic degradation of fungal cell walls and chitin
- 1995
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Ingår i: Biometals. - : Rapid Science Publishers. - 0966-0844 .- 1572-8773. ; 8:1, s. 12-18
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Tidskriftsartikel (refereegranskat)abstract
- The capacity of chitin (from crab shells) and of fungal cell walls from Trichoderma harzianum to accumulate zinc, cadmium and mercury was studied as well as the effects of adsorbed metals on the enzymatic hydrolysis by Novozym 234 of the two substrates. The total adsorbing capacity with respect to these metals was estimated to be at least 10 mmol kg(-1) chitin (dry weight) and 50 mmol kg(-1) fungal cell walls (dry weight), respectively, at pH 6.1. Enzymatic digestion of fungal cell walls preloaded with mercury and cadmium was significantly reduced, while zinc did not cause any significant inhibition. The effect of metal complexation by chitin on the enzymatic digestion was not as pronounced as for fungal cell walls. This could reflect the fact that chitin sorbed a lower total amount of metals. The inhibitory effect of metals on the enzymatic hydrolysis was caused by the association of the metals with the two substrates and not by the presence of free metals in solution.
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