| 61. |
- Herz, Annette, et al.
(författare)
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First use of pheromones to detect phenology patterns and density relationships of pine sawflies in German forests
- 2000
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Ingår i: Agricultural and Forest Entomology. - : Wiley. - 1461-9555 .- 1461-9563. ; 2:2, s. 123-129
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Tidskriftsartikel (refereegranskat)abstract
- 1 Monitoring studies of pine sawflies with pheromone traps were performed for the first time in Germany. Pheromone traps baited with species-specific pheromone substances were installed in pine forests at different locations in Bavaria, Brandenburg and Lower Saxony during two years. 2 It was possible to track the flight phenology of Diprion pini, Gilpinia pallida and Neodiprion sertifer reliably and to get information about the number of generations of these species in 1997 and 1998. 3 A clear relationship between trap catch and population density could not be detected, but qualitative changes in trap catch caused by different density levels were observed. 4 For D. pini, trap catches were different among endemic populations of different forest types. Furthermore, catches of males reflected the results from the regular cocoon collections by foresters during the previous winter. 5 For N. sertifer, trap catches in endemic populations were well separated from trap catches on sites with higher sawfly densities. However, no significant correlation between trap catch and sawfly density or defoliation level could be found. These results suggest that the efficacy of the pheromone traps probably varied with biological features (sex ratio, density level, immigration) of the particular population.
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| 62. |
- Holmberg, Erland, et al.
(författare)
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Reaction conditions for the resolution of 2-methylalkanoic acids in esterification and hydrolysis with lipase from Candida cylindracea
- 1991
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Ingår i: Applied Microbiology and Biotechnology. - 0175-7598. ; 35:5, s. 572-578
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Tidskriftsartikel (refereegranskat)abstract
- We have demonstrated resolution of 2-methylalkanoic acids using lipase from Candida cylindracea as a catalyst. The resolution of 2-methyldecanoic acid was more successful than that of 2-methylbutyric acid both by esterification and hydrolysis. This indicates that the resolution of the acid is dependent on the chain length of the acid moiety. The chain length of the alcohol moiety of the ester affected the resolution of the long-chain acid only. Using esterification, (R)-2-methyldecanoic acid was produced in an enantiomeric excess (e.e.) of 95% (E = 40). If the enantiomeric ratio is low (E = 3.6), as in the resolution of 2-methylbutyric acid, esterification combined with a high equilibrium conversion could be used to yield the remaining acid in a high e.e. In the hydrolytic reactions, the e.e. and the equilibrium conversion were dependent on the pH and the presence of CaCl2. When octyl 2-methyldecanoate was hydrolysed at pH 8.0 in the presence of CaCl2, the (S)-acid was formed with an e.e. of 80% (E = 9), but when the hydrolysis was carried out at pH 7.5 without CaCl2, a very low e.e. and a low equilibrium conversion were observed. The latter conditions allowed the esterification of 2-methyldecanoic acid with 1-octanol even in aqueous medium.
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| 63. |
- Högberg, Hans-Erik, et al.
(författare)
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Biocatalysis as a useful tool in pheromone synthesis. Enantiomerically pure building blocks from baker's yeast reductions and enzyme catalysed resoluti
- 1994
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Ingår i: Catalysis Today. - : Elsevier BV. - 0920-5861. ; 22:3, s. 591-606
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Tidskriftsartikel (refereegranskat)abstract
- Biocatalytical methods are presented which provide useful building blocks for pheromone synthesis. Examples of the utility of this approach are the preparation of building blocks for the synthesis of stereochemically pure isomers of pine sawfly pheromones and some other pheromones. Enantiom- erically pure ( 98% ee) 2-methyl-1-alkanols 2 were obtained via baker's yeast reduction of suitable α,β-unsaturated aldehydes, and by using lipases from Pseudomonas to effect resolution by transesterification of suitable racemic precursors to 2-methyl-1-alkanols 2 which gave high enantiomeric ratios E > 100. The resolution by esterification mediated by lipase from Candida rugosa of racemic 2-methylalkanoic acids also gave high enantiomeric ratios E> 100 after having improved the reaction conditions by regulating water activity, by choice of the appropriate complimentary substrate alcohol and by adjusting the initial equivalents of the latter present at the start. Also discussed is the separation of diastereomers of diprionol 1, which is naturally occurring in the pine sawfly Neodiprion sertifer, where it is the direct precursor of its pheromone.
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| 64. |
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| 65. |
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| 66. |
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| 67. |
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| 68. |
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| 69. |
- Högberg, Ida, et al.
(författare)
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Brightness development of a hydrogen peroxide bleached spruce TMP. Comparisons of pre-treatments with DTPA and a separable chelating surfactant
- 2012
-
Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 27:1, s. 50-55
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Tidskriftsartikel (refereegranskat)abstract
- In this investigation a new type of recoverable complexing agent (chelating surfactant) has been compared with a conventional complexing agent; diethylenetriamine pentaacetic acid (DTPA), in the metal ion sequestering of thermomechanical pulps (TMP) to be hydrogen peroxide bleached. After different degrees of washing of the pulps, bleaching experiments at different total alkali charges were performed with and without sodium silicate additions, and the ISO brightness of hand-made sheets was measured. The residual hydrogen peroxide in the bleaching liquor was also determined. No significant difference in either the brightness development or the residual hydrogen peroxide content could be detected between the pulps treated with equivalent molar ratios of the different complexing agents. Furthermore, the recovery of the chelating surfactant-manganese complexes from laboratory made white water by froth flotation was also studied. Two different foaming agents; sodium dodecyl sulphonate (SDS) and dimethyldodecylamine oxide (DDAO), were tested in the froth generation. After an addition of 160 ppm of DDAO, more than 80% of the manganese chelates could be recovered in the foam, containing 3% of the initial water mass.
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| 70. |
- Högberg, Ida, et al.
(författare)
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The Interaction Parameter in Binary Surfactant Mixtures of a Chelating Surfactant and a Foaming Agent.
- 2010. - 138
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Ingår i: TRENDS IN COLLOID AND INTERFACE SCIENCE XXIV. - Berlin : Springer. - 9783642190377 ; , s. 17-20
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Konferensbidrag (refereegranskat)abstract
- The micellisation in binary mixed surfactant systems of a chelating surfactant and a foaming agent has been studied by surface tension measurements in order to calculate the interaction parameter (beta). 2-dodecyldiethylenetriamine pentaacetic acid, 4-C(12)-DTPA, is an amphoteric chelating surfactant applicable for removing disturbing metal ions from industrial processes, or for heavy metal decontamination of soil or leachate. 4-C(12)-DTPA contains multiple donor atoms and forms very stable coordination complexes with metal ions. The metal complexes can easily be recovered from water by flotation, if the foaming is enhanced by a foaming agent with strong interactions to the chelating surfactant. Two foaming agents were examined, one cationic and one anionic. As expected, strong interactions were found between the negatively charged 4-C(12)-DTPA and the cationic dodecyltrimethylammonium chloride, DTAC. The influence of metal ion chelation, as well as pH, on the interaction parameter was also investigated.
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